Boosted corvette tuning help

[HateWhatOwnsYou]

I recently got my car tuned from a reputable guy a couple hours away, everything seemed good and had no issues on the dyno. made 969 to the wheels
Now driving on the street with a real load im pushing water.... i understand this could be in the tune or my heads just cant hold the pressure and before i pull the heads to o ring them or something i want to see if i can do something with the tune to help
a reputable corvette guy i know says i need more timing (like 22) and the motors probably knocking

the plug is #8 and from the attached log, 4th gear

Motor:
YSI- 24psi
E85
10.8:1 comprression
stock crank
forged rods and pistons
Ported 241 heads
jam cam
ARP studs (had these at 70ftlbs's, redid at 80ftlbs and still pushes water)

IMG_5065.jpgIMG_5064.jpgnew plug pull.hpltune from dynotune.hptVCM Scanner.cfg

[kingtal0n]

I cant open the log from this computer but,

You should be around 15* of timing with 105*F to 112*F intake air temps to start. Keeping IAT low is part of the equation but its hard with a supercharger, I know.

I would not run more than say 17 or 18* total timing by redline with 22 to 24psi of boost.

If I was going to dyno tune that combo I would start at 13* and work my way to 15* to see what there is to be gained. Probably very little.

Pushing water is a sign of a pressure spike issue which means too much timing advance or there is an issue with the combustion chamber design (hot spots, wrong heat range plugs, etc..) Or the fuel quality is poor (60% to 75% ethanol content is fine).
You should be using a heat range 7 or 8 Iridium spark plug. Copper is fine to tune with but switch to iridium once its tuned properly.

The correct response is to reduce timing or compression ratio or address the issues in the combustion chamber or with IAT.
If you O-ring the block it just means the pressure will go somewhere else (through a piston) then you will have chunks of piston flying apart instead.

When the engine loads on the street it becomes gear dependent. The rate of change of engine RPM slowing down as each gear increases numerically 1,2,3,etc... is slowing down the engine acceleration which means less timing is necessary to achieve the same pressure integral. So the slower the engine accelerates the less timing is desired. A typical tuning mistake is to tune on a dynojet or some lightweight roller and then load the engine up in a high gear with that tune, thus slowing the engine rate of change and dramatically increasing the instantaneous pressure rise in the cylinder.

With that much boost and power I would recommend
1. Use an EGT gauge to identify correct timing range
2. Use the minimum timing necessary which still keeps the EGT within a safe range

You can always reduce timing to reduce cylinder pressure at the risk of throwing fire into the exhaust and rising EGT.
If this results with the EGT beginning to get out of control (at the correct power output i.e. 100lb/min = 900rwhp, etc) it means the fuel quality and temperature can't keep up with the compression ratio at that combustion pressure. This is rare on E60-85 (never seen it happen on alcohol fuels, its more of a race gas scenario) so I don't think you will have this issue, but if you ever do, the correct response is NOT to increase timing to lower the EGT, instead you must either reduce compression ratio, raise octane, or inject 100% distilled water to control EGT. NEVER increase timing to deal with an EGT rise when engine supplied pressure is over double atmospheric (more than roughly 14psi of boost).

[HateWhatOwnsYou]

I cant open the log from this computer but,

You should be around 15* of timing with 105*F to 112*F intake air temps to start. Keeping IAT low is part of the equation but its hard with a supercharger, I know.

I would not run more than say 17 or 18* total timing by redline with 22 to 24psi of boost.

If I was going to dyno tune that combo I would start at 13* and work my way to 15* to see what there is to be gained. Probably very little.

Pushing water is a sign of a pressure spike issue which means too much timing advance or there is an issue with the combustion chamber design (hot spots, wrong heat range plugs, etc..) Or the fuel quality is poor (60% to 75% ethanol content is fine).
You should be using a heat range 7 or 8 Iridium spark plug. Copper is fine to tune with but switch to iridium once its tuned properly.

The correct response is to reduce timing or compression ratio or address the issues in the combustion chamber or with IAT.
If you O-ring the block it just means the pressure will go somewhere else (through a piston) then you will have chunks of piston flying apart instead.

When the engine loads on the street it becomes gear dependent. The rate of change of engine RPM slowing down as each gear increases numerically 1,2,3,etc... is slowing down the engine acceleration which means less timing is necessary to achieve the same pressure integral. So the slower the engine accelerates the less timing is desired. A typical tuning mistake is to tune on a dynojet or some lightweight roller and then load the engine up in a high gear with that tune, thus slowing the engine rate of change and dramatically increasing the instantaneous pressure rise in the cylinder.

With that much boost and power I would recommend
1. Use an EGT gauge to identify correct timing range
2. Use the minimum timing necessary which still keeps the EGT within a safe range

You can always reduce timing to reduce cylinder pressure at the risk of throwing fire into the exhaust and rising EGT.
If this results with the EGT beginning to get out of control (at the correct power output i.e. 100lb/min = 900rwhp, etc) it means the fuel quality and temperature can't keep up with the compression ratio at that combustion pressure. This is rare on E60-85 (never seen it happen on alcohol fuels, its more of a race gas scenario) so I don't think you will have this issue, but if you ever do, the correct response is NOT to increase timing to lower the EGT, instead you must either reduce compression ratio, raise octane, or inject 100% distilled water to control EGT. NEVER increase timing to deal with an EGT rise when engine supplied pressure is over double atmospheric (more than roughly 14psi of boost).

ok thanks for the reply

my plugs are br7ef's and the timing mark is to the bend of the strap, whats the benefit with iridium?
my IAT's could be part of the issue, they are getting into the 130's.....

what are acceptable EGT's?

im also going to add steam ports to the rear of the heads, currently only has the front 2.

IMG_5071.jpgIMG_5072.jpgIMG_5073.jpg

[HateWhatOwnsYou]

is this a decent attempt to pull some timing around 5200rpn to soften it up?

[kingtal0n]

why is there a low octane map on the left, and a high octane map on the right. Which map are you using? Did you realize you changed a different map? Or are you just showing me old vs new?

As far as timing, first you need to make sure there are no other maps involved. There are several ways to impact timing, under "base corrections" the "fuel", "iat", and "ect" maps for example all affect timing if they are used. Don't just assume the numbers in the high octane map are final for example.

Now on the the timing profile. Do you have experience with distributors? The timing curve should be somewhat similar with the caveat that around peak torque we usually soften it up a bit as you have attempted to do. However you really need a torque curve from a dynometer because many high performance engine often ride peak torque to redline or nearly so. So it can be difficult to tell just by the map how the torque is going to be affected by your timing inputs.

The only real issue I see with the curve is that there are too large of changes from one cell to the next after the 'distributor' goes 'all in'. Take a look at my pump gas timing curve for example.



at LOW rpm you must be very conservative with timing. When to go "all in" depends on the final gear ratio you will use at WOT for extended duration; In other words if you wanted to use overdrive gear from a very low RPM with to 200mph at full torque for a 2 mile race you will go 'all in' later than if the car is strictly 1/4 mile and never goes WOT in overdrive. Likewise if the vehicle is very heavy this is similar to using a numerically low gear ratio as it also slows the rate of engine acceleration. Another factor is compression ratio, the higher the compression the later you would push full timing in the RPM range. Fuel quality is also a factor, low octane fuels as 87 and 93 octane are much less tolerant of high timing values in general and this is exacerbated by low rpm due to a combination of low rate of change of engine rpm and the tendency of the fuel to react faster with high heat input of forced induction.


I recommend
from 2000rpm to 3000rpm I would move from say 10* to 12* only. Then from 3000rpm to 4400rpm move from 12 to 13.5*
from 4400 to peak torque move to 14*, then through peak torque back to 13.5 to 13.8 range, then if you exit peak torque by 5800rpm (mild cams or dropping boost) back to 14* pushing maybe 14.5 to 14.8* by redline. There should not be any values over 15* anywhere in the final row IMO. Not with your compression ratio anyways.

Then you would dynometer that and add 1.2 to 1.5* across the board (for a peak of say 15.5 to 16.3* total by redline (on 65 to 75% Alcohol) and re-check your torque curve with zero smoothing on a dynojet and compare. Anywhere it gains more than 5% torque (say from 400ft*lbs to 420ft*lbs or from 800 to 840) is a win and should be coupled to a drop in EGT , say 40 to 60*F perhaps even 80*F depending where the sensor is located (preferably pre-turbine on a turbo setup). Gains of less than 5% are negligible and you should remove the added timing because when the vehicle hits the actual road that extra timing, even if it gave extra power on the dyno, could damage the engine in real-street situations because of increased pressure.

E85 is very tolerant of high timing values and many run 18 or 20* in your situation, however not with that compression ratio so high. So don't be fooled when looking at low compression engines on E85 using 18 and 20* of timing, they are 9:1 its fine. But at 10:1 and 11:1 compression timing is not your friend. I would be surprised if that engine will want more than 13 or 14* total, if that.` Put it this way, If you can keep pulling out timing, lets say from 14 to 12 to 10* , and get a similar torque curve, and similar EGT, then that is a good thing, use the least amount of timing necessary.

As to EGT the number itself is irrelevant; every EGT sensor and placement will result with a different number. Instead, what we focus on is the difference from run to run. 1300*F this time and 1250*F next time for example. Or if the number sky rockets beyond 1400*F to say 1440 or 1550*F is a potentially dangerous situation. You must use common sense with temperature, if it seems too high it probably is. Metal can melt, materials will warp, valves can get too hot. 100% distilled water is the only thing that can really control EGT besides turning down the power so keep that in mind, it's better to reduce timing and use water injection than it is to advance timing to control EGT, even if it costs power, because the name of the game is engine longevity not peak power, unless you are racing for money or fame of course.

Advantage of iridium for forced induction engines is consistency and long life. It's the last thing I do to an engine after street tuning before hitting the dyno for the final dyno-tuning. I've just done it that way for 20 years on every forced induction engine, 2jz, sr20, rb26, etc... thought I'd mention it.

[HateWhatOwnsYou]

why is there a low octane map on the left, and a high octane map on the right. Which map are you using? Did you realize you changed a different map? Or are you just showing me old vs new?

As far as timing, first you need to make sure there are no other maps involved. There are several ways to impact timing, under "base corrections" the "fuel", "iat", and "ect" maps for example all affect timing if they are used. Don't just assume the numbers in the high octane map are final for example.

Now on the the timing profile. Do you have experience with distributors? The timing curve should be somewhat similar with the caveat that around peak torque we usually soften it up a bit as you have attempted to do. However you really need a torque curve from a dynometer because many high performance engine often ride peak torque to redline or nearly so. So it can be difficult to tell just by the map how the torque is going to be affected by your timing inputs.

The only real issue I see with the curve is that there are too large of changes from one cell to the next after the 'distributor' goes 'all in'. Take a look at my pump gas timing curve for example.

Attachment 102197

at LOW rpm you must be very conservative with timing. When to go "all in" depends on the final gear ratio you will use at WOT for extended duration; In other words if you wanted to use overdrive gear from a very low RPM with to 200mph at full torque for a 2 mile race you will go 'all in' later than if the car is strictly 1/4 mile and never goes WOT in overdrive. Likewise if the vehicle is very heavy this is similar to using a numerically low gear ratio as it also slows the rate of engine acceleration. Another factor is compression ratio, the higher the compression the later you would push full timing in the RPM range. Fuel quality is also a factor, low octane fuels as 87 and 93 octane are much less tolerant of high timing values in general and this is exacerbated by low rpm due to a combination of low rate of change of engine rpm and the tendency of the fuel to react faster with high heat input of forced induction.


I recommend
from 2000rpm to 3000rpm I would move from say 10* to 12* only. Then from 3000rpm to 4400rpm move from 12 to 13.5*
from 4400 to peak torque move to 14*, then through peak torque back to 13.5 to 13.8 range, then if you exit peak torque by 5800rpm (mild cams or dropping boost) back to 14* pushing maybe 14.5 to 14.8* by redline. There should not be any values over 15* anywhere in the final row IMO. Not with your compression ratio anyways.

Then you would dynometer that and add 1.2 to 1.5* across the board (for a peak of say 15.5 to 16.3* total by redline (on 65 to 75% Alcohol) and re-check your torque curve with zero smoothing on a dynojet and compare. Anywhere it gains more than 5% torque (say from 400ft*lbs to 420ft*lbs or from 800 to 840) is a win and should be coupled to a drop in EGT , say 40 to 60*F perhaps even 80*F depending where the sensor is located (preferably pre-turbine on a turbo setup). Gains of less than 5% are negligible and you should remove the added timing because when the vehicle hits the actual road that extra timing, even if it gave extra power on the dyno, could damage the engine in real-street situations because of increased pressure.

E85 is very tolerant of high timing values and many run 18 or 20* in your situation, however not with that compression ratio so high. So don't be fooled when looking at low compression engines on E85 using 18 and 20* of timing, they are 9:1 its fine. But at 10:1 and 11:1 compression timing is not your friend. I would be surprised if that engine will want more than 13 or 14* total, if that.` Put it this way, If you can keep pulling out timing, lets say from 14 to 12 to 10* , and get a similar torque curve, and similar EGT, then that is a good thing, use the least amount of timing necessary.

As to EGT the number itself is irrelevant; every EGT sensor and placement will result with a different number. Instead, what we focus on is the difference from run to run. 1300*F this time and 1250*F next time for example. Or if the number sky rockets beyond 1400*F to say 1440 or 1550*F is a potentially dangerous situation. You must use common sense with temperature, if it seems too high it probably is. Metal can melt, materials will warp, valves can get too hot. 100% distilled water is the only thing that can really control EGT besides turning down the power so keep that in mind, it's better to reduce timing and use water injection than it is to advance timing to control EGT, even if it costs power, because the name of the game is engine longevity not peak power, unless you are racing for money or fame of course.

Advantage of iridium for forced induction engines is consistency and long life. It's the last thing I do to an engine after street tuning before hitting the dyno for the final dyno-tuning. I've just done it that way for 20 years on every forced induction engine, 2jz, sr20, rb26, etc... thought I'd mention it.

you are correct in the assumption, i only messed with the one since i dont know what im doing anyways and wanted to give it a shot.
and i have zero experience with any of this lol im am tech savy and mechanically inclined but am clueless to all this tuning stuff (aside from atvs which is nothing compared to this stuff)
so modifying the table i did took several attempts, i should probably youtube the subject to get a better idea of how to change the numbers and smooth them. i also left the bottom right around 19 because i assumed it would be ok so i just softened up the middle.
youre attached file says its invalid for some reason.

would the dyno sheet from the existing tune be good enough of a reference for the torque curve?
IMG_4910.jpg

[HateWhatOwnsYou]

135 timing.JPGtiming charts.JPG

[kingtal0n]

make sure to check the 'base' table under 'fuel', it should be called 'afr advance' there can be timing adjustments there.
Actually it may be preferable to use that table because you are maxing the 1.2g/cyl limit unless the tune is scaled. Which is another issue to watch out for.

Look at the injector size and make sure it matches your actual injector size before proceeding.

Now, I notice something strange in the boost curve, it does not seem to match the torque curve well. I don't think that was a dynojet? It kind of looks like a dynojet but it doesn't say dynojet.
Its very important to use a dynojet because a dynojet cannot be fooled. It will reveal a more complete picture of how the engine is running. Also, always use Smoothing = 0 when performing diagnostics like this. that smoothing is going to hide perturbations in the curve we need to see.


In any case, it looks good on paper so to speak. So lets talk about the torque vs timing now.
Assuming you hit the 1.2g/cyl limit before 4000rpm and the tune is NOT scaled:

Notice at 5k the torque is very close to peaking, and by 6k there is a definite peak. So your 'softest' timing spot should be 6k and it should begin softening up around 4800. Then the torque more or less stays near peak, so keep the timing down until say 6500 to 7000 where you can add back a half a degree or .75 of a degree by redline since torque is falling.
Torque is a good indicator of cylinder pressure and so it can be used to judge where to pull timing for safety. So we would say that peak cyl pressure is likely around 6k, the peak torque.

To reiterate the timing should be increasing from 3k to 4400-4800 and then softening up slightly through peak torque area (the rest of the graph).
Pretty close to what you have now shown in that picture, its almost perfect, good job
In general, never use the same timing value from cell to cell, next to each other the timing should always be changing.
Below 3k, you would need to see where the boost and engine flow rate puts the g/cyl, it may not be maxed out at 1.2g/cyl before 3k so adjustments on the final row might be doing nothing. Which means you would need to pay more attention to the numbers higher up the graph for that "spooling" region.

Next you should smooth it. There is an interpolation and a smoothing feature on the top of the graph, select from say 3k to 4400 and hit one of them to see the smoothing action. Then highlight 4800 through 6000 (or take it 3 or 4 cells at a time) and keep smoothing. The goal is to create a curve where the timing from cell to cell is very smooth, and you can visually check using the graph button on the top, it can show you a visual representation of the curve.

[HateWhatOwnsYou]

make sure to check the 'base' table under 'fuel', it should be called 'afr advance' there can be timing adjustments there.
Actually it may be preferable to use that table because you are maxing the 1.2g/cyl limit unless the tune is scaled. Which is another issue to watch out for.

Look at the injector size and make sure it matches your actual injector size before proceeding.
ATTACHED ARE SOME SCREEN SHOTS OF THE TABLES, ONE OF THEM MATCHES FIC INJECTOR DATA BUT THE THE REST DONT, HE DID MENTION THE DATA HE GOT FROM THEM WASNT WORKING CORRECTLY, IM USING FIC 1440'S

Now, I notice something strange in the boost curve, it does not seem to match the torque curve well. I don't think that was a dynojet? It kind of looks like a dynojet but it doesn't say dynojet.
Its very important to use a dynojet because a dynojet cannot be fooled. It will reveal a more complete picture of how the engine is running. Also, always use Smoothing = 0 when performing diagnostics like this. that smoothing is going to hide perturbations in the curve we need to see.
YES IT WAS A DYNOJET, BUT ITS POSSIBLE IT WAS SMOOTHED, IM NOT SURE WHAT THE SETTINGS WERE WHEN HE WAS TUNING IT....

In any case, it looks good on paper so to speak. So lets talk about the torque vs timing now.
Assuming you hit the 1.2g/cyl limit before 4000rpm and the tune is NOT scaled:

Notice at 5k the torque is very close to peaking, and by 6k there is a definite peak. So your 'softest' timing spot should be 6k and it should begin softening up around 4800. Then the torque more or less stays near peak, so keep the timing down until say 6500 to 7000 where you can add back a half a degree or .75 of a degree by redline since torque is falling.
Torque is a good indicator of cylinder pressure and so it can be used to judge where to pull timing for safety. So we would say that peak cyl pressure is likely around 6k, the peak torque.

To reiterate the timing should be increasing from 3k to 4400-4800 and then softening up slightly through peak torque area (the rest of the graph).
Pretty close to what you have now shown in that picture, its almost perfect, good job
In general, never use the same timing value from cell to cell, next to each other the timing should always be changing.
Below 3k, you would need to see where the boost and engine flow rate puts the g/cyl, it may not be maxed out at 1.2g/cyl before 3k so adjustments on the final row might be doing nothing. Which means you would need to pay more attention to the numbers higher up the graph for that "spooling" region.

Next you should smooth it. There is an interpolation and a smoothing feature on the top of the graph, select from say 3k to 4400 and hit one of them to see the smoothing action. Then highlight 4800 through 6000 (or take it 3 or 4 cells at a time) and keep smoothing. The goal is to create a curve where the timing from cell to cell is very smooth, and you can visually check using the graph button on the top, it can show you a visual representation of the curve.

answered a couple questions in the quote above in red^^
attached are all the tables from the base corrections and the injector info, the fuel- base table is all zero's and fuel-multi is all 1.0. Im going to guess the multi table is what youd use to scale it correct?


thanks again for the detailed replies, really appreciate it
FUEL TABLE.JPGSPARK BASE CORRECTIONS.JPG

[kingtal0n]

Look in a log and find where g/cyl hits 1.19 to 1.2 and maxes out, what boost pressure and what RPM does it reach 1.2? Thats the point where the timing map is maxed out to the bottom row.

Im guessing you don't have an EGT gauge. I Would say make a pass with the new timing values but do it in a gear besides final drive (1:1) like 2nd or 3rd if using a manual transmission. See if the engine feels smoother. It should be a noticeable difference with the lower values and should still feel just as fast. I Know its hard to tell but without an EGT or DYno the only thing we can do is feel the differences. If it got noticeably smoother that is good. Also it should stop pushing water regardless. Im curious what a compression test would reveal, have you ever compression tested the engine? Just 1 cylinder is fine. 175psi cranking?

[HateWhatOwnsYou]

Look in a log and find where g/cyl hits 1.19 to 1.2 and maxes out, what boost pressure and what RPM does it reach 1.2? Thats the point where the timing map is maxed out to the bottom row.

Im guessing you don't have an EGT gauge. I Would say make a pass with the new timing values but do it in a gear besides final drive (1:1) like 2nd or 3rd if using a manual transmission. See if the engine feels smoother. It should be a noticeable difference with the lower values and should still feel just as fast. I Know its hard to tell but without an EGT or DYno the only thing we can do is feel the differences. If it got noticeably smoother that is good. Also it should stop pushing water regardless. Im curious what a compression test would reveal, have you ever compression tested the engine? Just 1 cylinder is fine. 175psi cranking?

i think these are correct, now one thing to note in my logs. i cannot figure out how to get the software to read the same manifold pressure as my boost gauge, it reads 9ps at idle with 12hg of vaccuum. now im assuming the map is reading atmosphere and with the 12hg of vac it makes it 9psi atmoshere..... i think..... maybe... idfk....

here are the files, so basically from 3500 and on its reading the final row.
1.2.JPG1.95.JPG

i do not have an EGT gauge and no i have never done a compression test either.

what do you mean by should feel smoother? id say it drives smooth as is.... even when pushing water lol

[kingtal0n]

usually when the timing is pushed to the brink of cylinder pressure spikes, they will show up on a dynograph as a jagged curve with some repeating frequency. Which is one reason we want smoothing=0. Those are intermittent pressure spikes, as in every couple hundreds of cylinder events one of them spikes 100-300psi higher than the rest or something like that. Depends on many factors and is fairly typical in gasoline applications. The engine will 'push harder' for a moment(1/10000 of a second?) which is why we can see it as a jagged curve on the dyno output sometimes. This also tends to cause the engine to feel rough or run rough, or uncertain. The human brain cannot sense speed, it can only sense acceleration. Like right now earth is moving quite fast both velocity and rotational speed, but you cannot tell because you are not accelerating appreciably. So for example when the horsepower on a dyno plot reaches some number, and then holds that number, you will generally feel a deceleration from that point, since vehicle drag is constantly reducing acceleration even while power output remains consistent. Anyways, its just a curiosity to us because we don't need to 'feel' anything, what we really want is a dyno plot and an EGT read to make sure the engine is doing what we want it to do. That is, stay cool enough that nothing is in danger of melting, and use the least amount of timing possible to keep the pressure spike from occurring.

to make hptuners read in actual psi you need a user math formula. At the top one of the options is 'user math' and you input the variables (pressure) and then have it subtract (or add) as necessary by simply writing the formula. something like [pressurexyz123] - 14.5
I have user maths like that setup for mine but not on this computer, thats why i cant view your log or tune file

[HateWhatOwnsYou]

pull 13deg.png

welll the tune worked and it didnt explode so thats a plus, but it still pushed some water.... nowhere near as much as before

i do have a side question, i only have 4 studs vs the 6 on "better" blocks and my 241 heads are considered "thin deck".... you mentioned earlier that if i kept the pressure in the motor with an o-ring something else would fail... but what if these parts are the weak link and not the bottom end?



one other thing, when i let off it advances quite fast, about instantly and theres still boost somewhat preset. what are the chances this could spike the cylinder pressure and push?

[kingtal0n]

Generally a bypass valve will relief boost pressure during a lift. Does the compressor surge? You want a clean bypass event- Whooosh without any surge to discharge boost pressure.

2. you can try removing more timing. The range of 13 to 15* is just a beginning test point. You should try 10* on a dyno and compare with 13 and 15 for example. the goal is to use the lowest number that still gives a safe EGT and reasonable power.

The only down side to removing timing is the EGT ramp effect. After a certain point, the EGT can skyrocket. For example
15* EGT moves from 800 -> 1250*F during the run
13* from 800 -> 1290*F
11* 800 -> 1310*F
9* 800 -> 1350*F
7* 800 -> 1450*F

notice the EGT skyrocketing between 7 to 9* in my example. This is why we should use Short runs when testing new, low timing values. A low timing value which provides a lot of heat to the exhaust isn't going to damage anything when it is kept very short.
There is always some EGT 'ramp' beyond which low timing values are unwanted. Are you familiar with sigmoidal function? The shape is like an S. You want to be near the low part of the "S", before it ramps up to the plateau. This is determinable using an EGT gauge by trial and error at various boost pressures.


the 'weak link' argument only works if you've done the engineering math for every component before building the engine. It's a strength of materials and advanced mechanics set of formulae which determines what will break, buckle, fracture, etc...
As novice mechanics (we are all) we rarely have access to that data. So it is better to reduce the stress on parts, rather than force them to contain that stress. Stress in mechanics is a general formula, force/area, so for example the piston surface area must put up with some force over it's area(ex. units of PSI can be stress) during each combustion event, and fracture beyond that stress along a specific orientation (general materials will be weakest along some specific angle). Typically the engines are designed with gaskets (i.e. head gaskets) that are weaker than their internal parts can withstand. In other words, we ALWAYS want to use a head gasket which is weaker than our piston/rod/etc. That means the gasket will blow out before the piston breaks, if that makes sense. I see you have forged piston/rod so if you are using a factory head gasket then it is possible upgrading the head gasket situation is 'fine' however, the caveat is you had better be absolutely sure what sort of pressure you are forcing the piston/rod to handle in lieu of the upgrade. In other words, Once you force a powerful gasket to hold any amount of pressure, lets pretend you weld the head to the engine for example (using a powerful gasket like an O-ring is practically similar) Now you will have no indication when the pressure is dangerously high, there won't be any water to warn you, there won't be any sign that the piston is taking abuse/beating. If you are 'blind' to the cry for help, don't check the plugs, don't test the engine on a dyno under it's most loaded, hot situation, the high pressure *will* find another way out if it can't blow the gasket. And when the piston is forged, it can take alot of abuse over time, which means you could be hammering the rod bearings run after run without realizing it, even while the piston puts up with the high stress, other parts will suffer around it with no indication to you visible. To put it another way, you really need to know what you are doing before you fully seal an engine up like that. The factory gaskets are 'engine saviors' in that they will be the warning signs that the engine needs help, adjustments, etc... So it is ALWAYS better to keep the weakest gasket you can possible get away with.
So to be clear I am not saying its a bad idea. Just that the OEM gaskets and weaker gaskets are going to favor longevity, and superior tuning. A very strong gasket and strong piston will put up with ABUSE, meaning it will be eating away at the other parts with no outward indication that something is wrong. The engine will seem to 'run fine' while the bearings take a beating and throw metal through the engine, ruin everything, damage the block, make it un-rebuildable. You would lose everything with no warning.

The safest thing to do is decrease the stress, deal with the weak gaskets, even if they are the weak link. Its better to work around them than to fully seal the engine up and have it potentially ruin every other part besides the gasket.

What I would recommend before doing any extra O-ring or superior gasket is:
1. replace the head gaskets and refinish the surfaces, as pushing water may have worn "pathways" inside/between it, which are easily traversed now. Think of the ants which have made a path in dirt. The ants are gone but now they left behind little tunnels, water has gouged the gasket potentially the deck surface on a micro scale. So it may need to cleaned up, re finished, back to nice and flat, and with a new gasket to fully re-seal. If using OEM gasket, use the OEM deck preparation method, make sure everything is clean and flat, like clean-room clean and laser flat as possible.
2. Let the engine heat cycle 100+ times before tuning up the boost. Just drive the car like a normal car for a month or so, with low boost. Have you ever tried to remove an old gasket vs new? The old ones tend to stick down more fully. This is because over time, with many heat cycles, they settle and bond more fully to their surface. You should never install a fresh gasket then turn up the power all the way the next day, it will surely not be ready.
3. get an EGT on it and remove timing to find the egt 'ramp' for your build. then add back a little timing to stay off the ramp. The ramp is where egt suddenly sky rockets, it will be very obvious in numerically high gears (1:1 or overdrive the EGT will rise rapidly with low enough timing values). Thanks to the EGT gauge there is no danger searching for the ramp; simply let off the gas pedal before the EGT rises too high. The only danger of using low timing is high EGT and with the EGT gauge there won't be any problem because you can clearly identify the temperature of exhaust.

[kingtal0n]

also i note your iat going too high. 150*F is too much. Before you run the engine again I would run a pressure test to 25psi (near your boost pressure setting).

Fill the compressor inlet with air from an air compressor all the way through to the intake manifold and find all the leaks. I think you have a leak. Otherwise, your intercooler is too small, or the blower is completely out of breath (compressor run off the map).

none of those things is good. You need the IAT to stay down near ambient. Its probably just a leak but that can be devastating to an engine so fix it asap.

here is a pressure test video to show first, testing the engine, notice the factory GM pcv valve leaking. You NEED a functioning pcv system but that is another story. The crankcase should be connected to the pre-compressor inlet, and the other end of the crankcase should be connected to the intake manifold through a BOOST worthy pcv valve. I use Supra Twin turbo pcv valve. If you need help setting up pcv I can provide more details.

https://www.youtube.com/watch?v=rYZmZqn3-x0

note near the end of the video the pressure is applied to the pre-compressor and the entire intercooler plumbing is pressurized. Always remove the crankcase vent and pull the dipstick to make sure you dont accidently pressurize the crank case. Being aware of the crankcase flow, and pcv setup, is part of high performance and part of the oil system so it is an essential part of tuning and care/maintenance. NEVER run a vent / breather.

[HateWhatOwnsYou]

also i note your iat going too high. 150*F is too much. Before you run the engine again I would run a pressure test to 25psi (near your boost pressure setting).

Fill the compressor inlet with air from an air compressor all the way through to the intake manifold and find all the leaks. I think you have a leak. Otherwise, your intercooler is too small, or the blower is completely out of breath (compressor run off the map).

none of those things is good. You need the IAT to stay down near ambient. Its probably just a leak but that can be devastating to an engine so fix it asap.

here is a pressure test video to show first, testing the engine, notice the factory GM pcv valve leaking. You NEED a functioning pcv system but that is another story. The crankcase should be connected to the pre-compressor inlet, and the other end of the crankcase should be connected to the intake manifold through a BOOST worthy pcv valve. I use Supra Twin turbo pcv valve. If you need help setting up pcv I can provide more details.

https://www.youtube.com/watch?v=rYZmZqn3-x0

note near the end of the video the pressure is applied to the pre-compressor and the entire intercooler plumbing is pressurized. Always remove the crankcase vent and pull the dipstick to make sure you dont accidently pressurize the crank case. Being aware of the crankcase flow, and pcv setup, is part of high performance and part of the oil system so it is an essential part of tuning and care/maintenance. NEVER run a vent / breather.

I do not get any surge and have a 52mm blowoff right after the blower.

I had a PCV setup on the car but around 800hp my crankcase wasnt being vented enough and was blowing the dipstick out. the previous shop i was using removed my setup and ran a -12 line to the oil fill and a 1/2" line to the valley and is now vented to atmosphere.


i do understand my IAT's are getting high, i actually didnt even notice on that run it was up to 150, but ive see 135 regularly.... i will check for leak but im going to guess my intercooler is undersized, its a A&A intercooler and is roughly 26"x10"x4... also the blower shouldnt be outta steam, im still below the max RPM and many people overspin the shit out of them.
how much do IAT's come into play with cylinder pressure? if i get my IAT's down is it possible it will also fix my main issue? or would that be a stretch?
im learning alot as im goin on this thing car, i think i have all my i's dotted and my t's crossed but there is always something i didnt catch or know about. (i also need a new driveshaft...... my stock one isnt happy)



i REALLLLLY dont want to pull the heads, but if i have to i can also put in a thicker gasket to help me out some... im using a cometic MLS gasket. when i forged the motor(couple years back) i didnt have to do any work to the deck or head surfaces so i suppose its possible the surface RA is not fine enough. i also didnt use any copper coat or stuff like that i see people mentioning about now

[kingtal0n]

E85 is extremely tolerant of high IAT, some people don't even use an intercooler at 1000 to 2000hp. It is very difficult to say how much the high IAT is impacting your issue, maybe not at all, or maybe its the straw that is breaking the camels back. We shouldn't rule it out at least until you do a pressure test.

The main reason you want a low IAT is because it reflects the efficiency of the blower/combo, and will help reduce the boost pressure throughout the intake system(the blower's rate is hard set by blower RPM whereas the boost pressure will go up or down with IAT), which may or may not help with the pushing water. Its more of a warning sign that something could be wrong. On a turbo car its a HUGE problem because every leaking air molecule adds to exhaust gas pressure but that wouldn't be the case here. The high IAT may also impact the timing profile (higher IAT = more energy input with the air = needs less timing advance) so that is a potential connection between the issue you are having.

As to the PCV system, I would simply take your new huge vent lines and run them properly to the compressor inlet (post air filter, pre compressor) so they can pull on the crankcase during boost. Like a factory turbo car.
THAT may have some impact on your pushing water. When the engine makes alot of cylinder pressure some of it sneaks past the top ring, and from there it wants to get into the crankcase. but if the crankcase has pressure (if its vented to atmosphere, it does, probably over 2psi in the crankcase is typical) then the piston ring seal will suffer, and they can 'flutter' or other weird issues related to cylinder pressure. It will lead to oil leaks, oil contamination, and more blow-by. Stuff starts 'blowing out' from every seal. I like to think of a proper pcv as a sort of 'seal protector' and the issue you are facing is a sealing issue, so this may be part of the solution for you ultimately.


I understand not wanting to pull the heads. Instead for now I then would keep reducing timing and check the EGT and go from there. As you pull timing the cylinder pressure peak will go down more and more so eventually it must stop pushing water. The only danger is a high EGT like I said before you must check that.

Also do a compression test if you get a chance, and remember to use 2 different compression testers because 1 is always bad. Write the numbers down too, using a decimal, like this: 167.4, 164.8, etc... be as accurate as possible because in the future when you do the NEXT compression test you will be able to compare them and get an idea of how the cylinder/rings/valves/etc is holding up (the seals)

And keep in mind your existing head gasket/head/deck may have minute pathways carved in it from pushing water already. Like ocean water erodes the rocky shore, like a waterjet can cut steel, water is a powerful abrasive molecule at high velocity. It might be worth turning the boost down and see whether its still pushing water. In other words if it can push water at 7psi then obviously something is wrong with the head/gasket/deck already and it needs service. Likewise if you find that turning down the boost from 23 to 19 'fixes' the issue then you can leave it there for a while until you get the EGT on it and do more dyno testing with lower timing values in the future. A combination of these things is best.

[HateWhatOwnsYou]

E85 is extremely tolerant of high IAT, some people don't even use an intercooler at 1000 to 2000hp. It is very difficult to say how much the high IAT is impacting your issue, maybe not at all, or maybe its the straw that is breaking the camels back. We shouldn't rule it out at least until you do a pressure test.

The main reason you want a low IAT is because it reflects the efficiency of the blower/combo, and will help reduce the boost pressure throughout the intake system(the blower's rate is hard set by blower RPM whereas the boost pressure will go up or down with IAT), which may or may not help with the pushing water. Its more of a warning sign that something could be wrong. On a turbo car its a HUGE problem because every leaking air molecule adds to exhaust gas pressure but that wouldn't be the case here. The high IAT may also impact the timing profile (higher IAT = more energy input with the air = needs less timing advance) so that is a potential connection between the issue you are having.

As to the PCV system, I would simply take your new huge vent lines and run them properly to the compressor inlet (post air filter, pre compressor) so they can pull on the crankcase during boost. Like a factory turbo car.
THAT may have some impact on your pushing water. When the engine makes alot of cylinder pressure some of it sneaks past the top ring, and from there it wants to get into the crankcase. but if the crankcase has pressure (if its vented to atmosphere, it does, probably over 2psi in the crankcase is typical) then the piston ring seal will suffer, and they can 'flutter' or other weird issues related to cylinder pressure. It will lead to oil leaks, oil contamination, and more blow-by. Stuff starts 'blowing out' from every seal. I like to think of a proper pcv as a sort of 'seal protector' and the issue you are facing is a sealing issue, so this may be part of the solution for you ultimately.


I understand not wanting to pull the heads. Instead for now I then would keep reducing timing and check the EGT and go from there. As you pull timing the cylinder pressure peak will go down more and more so eventually it must stop pushing water. The only danger is a high EGT like I said before you must check that.

Also do a compression test if you get a chance, and remember to use 2 different compression testers because 1 is always bad. Write the numbers down too, using a decimal, like this: 167.4, 164.8, etc... be as accurate as possible because in the future when you do the NEXT compression test you will be able to compare them and get an idea of how the cylinder/rings/valves/etc is holding up (the seals)

And keep in mind your existing head gasket/head/deck may have minute pathways carved in it from pushing water already. Like ocean water erodes the rocky shore, like a waterjet can cut steel, water is a powerful abrasive molecule at high velocity. It might be worth turning the boost down and see whether its still pushing water. In other words if it can push water at 7psi then obviously something is wrong with the head/gasket/deck already and it needs service. Likewise if you find that turning down the boost from 23 to 19 'fixes' the issue then you can leave it there for a while until you get the EGT on it and do more dyno testing with lower timing values in the future. A combination of these things is best.

Okay, whats the easiest way to log egt's? i obviously need to put a pyrometer in but is there a specific one i can wire to the pro link without any additional boxes or hardware?
cylinder 7 or 8 id guess but how far away from the manifold? 2"?

i was at 18psi before and 800hp and didnt have issues, so im going to say its the new blower and the 24psi the gasket doesnt like

ill grab a compression tester on my way home and check it tonight

[HateWhatOwnsYou]

Here’s some of my homework

6 strokes
#1 174psi
#2 176.5
#3 170.5psi 175
#4 175psi
#5 169 175.5
#6 174.5
#7 174.5
#8 176.5

10strokes 185psi

The ones that read low I did a second test on

[kingtal0n]

easiest way to log EGT is using a stand-alone. If you get an EGT with a 0-5v output like a wideband it would be the same thing as a wideband log for hptuners.

The cheapest way to log EGT is using an arduino ($20~) and a pyrometer thermocouple ($8?) it can be done to both sides of an engine for < $50 that way. But you need to know how to code and retrieve the data.

compression test reveals a very tight squeeze. Healthy engine.