I got a riddle for you... Explain how I made Less Hp with new cam and heads set up.

Okay guys, My tuner/buddy/ teacher and I are stumped. Previous set up

MSD atomic Air force
Stock LS2 Injectors
holley 102 DBC
4Inch CAI
LS7 MAF/ IAT
317 Heads
Patriot double Valve Springs
Manley Valves
LS2 head gasket
stock pushrods
ls7 lifters
long tubes
tr55's
3 inch exhaust
t56
4.10 Gears
Approx 9.5:1 compression
87 octane
LS swapped c10

The truck made 358Hp on mustang dyno

Story: Had a ticking lifter, tore the motor down ( bought used) to inspect. Found worn crank and rod bearings. Replaced them, found a failed lifter. Put a BTR stage 4 ls car cam. Measured pushrods (7.350? Cant remember but the engine builder measured for them) Shaved the 317 heads 60. LS9 Gaskets. New GM LS7 lifters. bumped compression to 10.5:1. Filled up with 93 Octane.

Made a dyno tune and a few pulls last night and it made 357.5 hp. How in the world is that possible. Same dyno, same everything. different cam, lifters, decked heads, new bearings, measure pushrods and new head gaskets. My tuner and I are dumbfounded. He's been in business since he stared tuning ( Grand national and fox body era) He's stupid smart but was busy last night. ( maybe we are missing something) The only difference I am seeing is last night my timing ran at 24 and the previous set up had timing set at 30.

What's the curve look like. Any how many cubes?

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Originally Posted by bmorrow8

Stock LS2 Injectors

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Show us a log with the duty cycle. Should be a good example of what the phrase "out of injector" looks like.

Why would you do all that work and run junk 87 octane. 91+ should be ran a minimum so you can make the most of the timing curve.

Would be more helpful to see the tune file and the log file with wideband readings.

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Originally Posted by 5FDP

Why would you do all that work and run junk 87 octane. 91+ should be ran a minimum so you can make the most of the timing curve.

Would be more helpful to see the tune file and the log file with wideband readings.

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Just to clarify, I'm running 93 on the current set up, Which is the stage 4 cam and milled heads. I forgot and ran 87 on the stock 317 heads and smaller cam the day I went for a dyno tune and dyno pull.I'll post a tune and they dyno log. Notice: it will not be a perfect tune but fuel trims we were hitting should be pretty close.

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Originally Posted by Srblacks13

What's the curve look like. Any how many cubes?

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the dyno curve? I'll have to ask my buddy to sent me a pic. I was so pissed I just left and didn't get a picture. 347.5 Cub in

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Originally Posted by blindsquirrel

Show us a log with the duty cycle. Should be a good example of what the phrase "out of injector" looks like.

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So I don't have a log of the dyno pull but I did go back and look at it. At 6000rpm, the Injector Duty was 83%

My engine Builder is thinking by milling the heads .060, we may have disrupted the cylinder air flow, maybe we changed the pattern? Made it less efficient?

Did it make that HP at same rpm? What does the torque look like? Really need to compare both graphs not just a peak number. Also interested in the tune changes between runs.

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Originally Posted by Sith

Did it make that HP at same rpm? What does the torque look like? Really need to compare both graphs not just a peak number. Also interested in the tune changes between runs.

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Yes. Same RPM. The Torque was lower on the new set up early on the dyno pull but caught up. I'll see if I can get the dyno Chart. He will overlap the dyno pulls so you can see the difference the the first and second engine set up. I'll also post both tunes.

For what it's worth, I called Texas Speed to ask them if they have ever shaved a head .060. He said you can not shave a 317 head that far bc you are cutting away too much of the chamber. He said I have shrouded my valves and the airflow is probably so bad it can't make power now. Makes sense to me. Just wish my engine builder would have knew this before hand. He hasn't shaved 317 heads before so he didn't know what it would do. Kinda sucks.

typically when you deck and lower the quench pad too low, you "unshroud" the valve. shrouding is the term for how close the wall is to the valve. if you open the valve to wall clearance up then you unshroud the valve. the shape of the shroud plays a fair role in dynamic cylinder flow. i would guess the quench pad is too low now and the flow diversion feature leading up to the quench pad is now not as effective. probably what TSP is telling you. increasing quench is typically a good thing, but as you may have just demonstrated, only if the dynamic flow profile remains efficient. In the testing labs, quench is typically dub'd "artificial octane" since a good quench design can boost detonation resistance.

Did you do port work as well? If yes, did you cc the intake and exhaust runners for total volume? i've seen a lot of heads that got overworked and dropped port velocity and ruined everything.

once again im sitting in a lecture so apologies if this is a long reply.

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Originally Posted by cobaltssoverbooster

typically when you deck and lower the quench pad too low, you "unshroud" the valve. shrouding is the term for how close the wall is to the valve. if you open the valve to wall clearance up then you unshroud the valve. the shape of the shroud plays a fair role in dynamic cylinder flow. i would guess the quench pad is too low now and the flow diversion feature leading up to the quench pad is now not as effective. probably what TSP is telling you. increasing quench is typically a good thing, but as you may have just demonstrated, only if the dynamic flow profile remains efficient. In the testing labs, quench is typically dub'd "artificial octane" since a good quench design can boost detonation resistance.

Did you do port work as well? If yes, did you cc the intake and exhaust runners for total volume? i've seen a lot of heads that got overworked and dropped port velocity and ruined everything.

once again im sitting in a lecture so apologies if this is a long reply.

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Thank you for the knowledge. That is interesting. No port work was done.

FWIW Mustang dynos can read completely different on the same vehicle by entering different vehicle weights/hp@50 numbers in the set up calibrations. I saw one car on a Musting dyno that was just shy of 400 RWHP and the builder say he was really hoping for over 400.The dyno operator changed the roller weight in the calibration and viola, the graph was printed over 400 hp. You can also do pulls with and without the load cell on. You might check with your dyno operator and make sure the dyno calibrations were the same and the pulls done with the same load. 317 heads use the same ports and 243/799 heads. Just have a bigger chamber. And with milling your heads that much you might want to double check your push rod length and stiffness because in your OP you state stock push rods.

do compression and leak down test to determine the condition of the engine after it was dissembled.

then check correct pushrod length, although the leak down would tell you if there holding the valves open.

.060 off a head is a bunch, but i cant see its causing that big of a shroud to the valve.

di you retune the PCM for the modifications you made to the engine, or still using the before tune?

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Originally Posted by bk2life

do compression and leak down test to determine the condition of the engine after it was dissembled.

then check correct pushrod length, although the leak down would tell you if there holding the valves open.

.060 off a head is a bunch, but i cant see its causing that big of a shroud to the valve.

di you retune the PCM for the modifications you made to the engine, or still using the before tune?

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an 1/8 inch is a fair amount of vertical removal. i wonder what the length of change in the quench ramp is from stock to 1/8" shave. if we knew the angle of the quench ramp in relation to the quench pad is wouldn't be too hard to math out; simple trig.

dyno graphs. need... picture. And exact detail which run was 87. 93. so far this is ridiculous, so completely bonkers situation I am not sure where to even begin

did you put this cam
Specs: 235/242 .621"/.592" 111+3

with oem pushrods?! lol is this a 6.0L....
do I understand that you have some kind of automatic transmission and a cam/engine that wants 65-7,800rpm with 21psi of boost
with exact length pushrods and solid lifters maybe it would have a chance. But there is a mismatch when you step over 230* of duration @ .050 with an automatic in a heavy vehicle and naturally aspirated. On a stock head no less. I'm surprised thats all you lost was 1hp lol. good job.

but see, you don't write the weight or post picture of dyno graph for diagnostics. Torque shows you cylinder pressure. Conditions vary you can see 2-5% up and down day to day. Such very limited capability without being able to see shape curve of picture... why do i waste t

look at their dyno run v ideo. Note the manual transmission, and 7 to 8k redline.
The video is absolutely terrible. the camera does not show what RPM but we know for sure from basic intuition that that line is approaching either 7 or 8k

Attachment 93108

thus the automatic transmission dilemma mismatch. You see, my personal opinion (saying it now) is that as the vehicle weight goes up (heavier) any typical auto (4l60e) and especially the heavy versions (4l80e & th400) need some serious working over when you want 8k 9krpm especially. Most will need a variety of 'fixes' just for reliable 7k performance. You basically need to become a transmission expert just to use an auto for personal racing (using a cam for 7k rpm). If you skip this step.... the consequences are the engine will never perform well/properly at higher rpm and the trans will fail and the project will sit or never make the power it should.

Now I am being a bit dramatic on purpose to emphasize the rules or steps that have been broken. But it remains to be seen how bad of a mismatch was commited... Need dyno graph to make further comments....

My old 68 C10 weighed 3660, not too portly by today's standards.

T56 is on his list.

1/16" off the heads is a lot. Small base circle cam probably...maybe stock length pushrods are not too far off...but stock pushrods obviously won't live long with the double springs and rpm. Maybe he just meant stock length pushrods on the list?