IAT temp = 153*F, tuning out IAT based timing with E85?

[balm]

Running E85 on a forge Lq9, 25-30psi of boost.

Looking at a pull, at the very end my IAT is at 153*, which pulls about 4* timing up top.
Currently running at 16* since I havent dyno tuned the car yet.
I am running water injection but only the 5gph nozzle which I plan to double up for more cooling but what is the general consensus(for E85) on on tuning out the IAT retard?

I'm thinking at 149 is where it would start to pull timing? so maybe shift the table?
Or maybe it wont matter as much since once the timing is tuned im thinking it will be around 20* or so at WOT anyways


IAT.PNG

[Ben Charles]

There is no one size fits all.. best thing to do is get that iat little more under control…

[smokeshow]

Water injection isn't super useful if you are running E85. The water will only serve to do what the ethanol is already doing really well...managing excessive cylinder temperatures. It doesn't do much for charge temps. Long as the engine is built well (loaded sentence...) I wouldn't be concerned about those IATs at the end of a pull on E85. Swap the water to methanol and let it eat.

[balm]

There is no one size fits all.. best thing to do is get that iat little more under control…

what temp IAT would you consider under control?

Water injection isn't super useful if you are running E85. The water will only serve to do what the ethanol is already doing really well...managing excessive cylinder temperatures. It doesn't do much for charge temps. Long as the engine is built well (loaded sentence...) I wouldn't be concerned about those IATs at the end of a pull on E85. Swap the water to methanol and let it eat.

Just did a bunch of reading on this and for some reason I miss understood that concept all these years. I thought water took care of charge temp also, boy I sure missed that important information.
I'll look into reintroducing methanol into the mix. now I will need to relocate my BOV again as its post injection...

[blindsquirrel]

Where is your IAT located?

[Ben Charles]

I never use water… meth always cooled more anyways and was more consistent then mixes and 100% meth was always faster..

[Ben Charles]

153 iat on 25-30 psi is actually really good considering boost pressure..

I’ve ran 250-300 iat temps with no intercooler on pure meth and was fine on 30 psi.. those rigs usually run mid 4s in the 1/8 too

[jon1440]

Running E85 on a forge Lq9, 25-30psi of boost.

Looking at a pull, at the very end my IAT is at 153*, which pulls about 4* timing up top.
Currently running at 16* since I havent dyno tuned the car yet.
I am running water injection but only the 5gph nozzle which I plan to double up for more cooling but what is the general consensus(for E85) on on tuning out the IAT retard?

I'm thinking at 149 is where it would start to pull timing? so maybe shift the table?
Or maybe it wont matter as much since once the timing is tuned im thinking it will be around 20* or so at WOT anyways


IAT.PNG

I was recently at the dyno also and looks like our build is very similar. My charge temps was in the 150's as well and timing topped at 20 degrees on E. I actually just discussed this with the dyno tuner. Since we are running ethanol we know we are better off because it'll cool off the charge, as least for me not before the cooled charge gets to the iat. If the cooling effect is happening after the iat then the last place to make sure nothing is damaging the engine, is spark plugs.

I've also thought of the methanol injection just to give some cushion. If the intake charge is lowered and the computer can see that it did in fact lower, then we wouldn't need to adjust the spark table to get the most out of the engine.

Options:

Either get cooler charge temps and resume the power quest.

Adjust spark table and watch the plugs closely.

Also got to remember, on the dyno the charge temps have had more than enough time to heat up because of the back to back runs.

From what I was seeing during my tuning secession, was that with every 1 degree up top, I was picking up 30-40hp. So I know we wasn't close to full potential. The iat knocked me down quite a bit. 5 degrees X 30hp is alot to give up. (Rough measurement) My plugs looked fine and from what I could see the best timing hadn't been achieved yet. These tables are safety features, doesn't mean its an absolute.

[balm]

153 iat on 25-30 psi is actually really good considering boost pressure..

I’ve ran 250-300 iat temps with no intercooler on pure meth and was fine on 30 psi.. those rigs usually run mid 4s in the 1/8 too

Interesting, do you not take advantage of cooling the cylinder for say hot spots? Cant say its happening but water cooling off those hot spots that could cause detonation sounds like it worth running some water through.
Atleast thats what ive read. Thats pretty darn hot, did you notice any drop in power once you start reaching that high?

Where is your IAT located?

Located about 6" from the TB, water/Meth nozzle is about 2' ahead.
Its not in the best spot for cooling so it could be prone to heat soak but it does drop back down after the pull so doesnt look like the sensor gets heat soak.

[balm]

I was recently at the dyno also and looks like our build is very similar. My charge temps was in the 150's as well and timing topped at 20 degrees on E. I actually just discussed this with the dyno tuner. Since we are running ethanol we know we are better off because it'll cool off the charge, as least for me not before the cooled charge gets to the iat. If the cooling effect is happening after the iat then the last place to make sure nothing is damaging the engine, is spark plugs.

I've also thought of the methanol injection just to give some cushion. If the intake charge is lowered and the computer can see that it did in fact lower, then we wouldn't need to adjust the spark table to get the most out of the engine.

Options:

Either get cooler charge temps and resume the power quest.

Adjust spark table and watch the plugs closely.

Also got to remember, on the dyno the charge temps have had more than enough time to heat up because of the back to back runs.

From what I was seeing during my tuning secession, was that with every 1 degree up top, I was picking up 30-40hp. So I know we wasn't close to full potential. The iat knocked me down quite a bit. 5 degrees X 30hp is alot to give up. (Rough measurement) My plugs looked fine and from what I could see the best timing hadn't been achieved yet. These tables are safety features, doesn't mean its an absolute.

Yea for me I made sure to spray before the IAT so the PCM sees actual temp of the air and I didnt want to mess with the other stuff.
I took apart my charge pipe today to add another bung for the 2nd nozzle and looks like I accidentally put the 3gph. WTF i could have sworn that was a 10 gph nozzle .

Using this calculator https://www.promracing.com/methanol.php
and at roughly 1300hp target I should be using roughly 1800ml/min nozzle. I have 3, 5, 10, 14 GPH nozzle.
I'm thinking using the 5(520ml/min) + 14 GPH(1200 ml/min) nozzle to start = which is pretty close to target.

What do you guys think? with e85 I dont intend to use the methanol as octain booster, I just want that air as cool as possible. and its not even summer yet...
Id still like to run 25% water for my piece of mind-for the cyl cooling.


30-40hp per degree seems a lot more than I expected to get but I guess that would make sense on why it drop quite a bit on 4&5 gear pull.

Screenshot_20220330-214416_dragy.jpg

[jon1440]

I think the best way to know if your setup can handle extra timing, even with the high iat's, is to watch the plugs. E85 is doing its own thing after all the sensors anyways, as for cooling. Having the assurance of actual cool air is a bonus though. From what I've seen with most boosted ls engines, best timing was achieved around 20-23 degrees. Its possible to add a degree of timing to the main spark table and see how it handles it. Look at the plugs and make sure all is good. I'd leave the flex iat spark table the way it is.

[eficalibrator]

Some general input if I may...

Spark vs IAT is about compensating for a change in burn rate, NOT how much total timing your engine will tolerate.

If you are using the IAT table to add timing (or reduce the amount of reduction at "normal" operating temps), why not just put that added timing right into the high octane table?

The whole purpose of the IAT spark modifier to react to either increases or decreases in charge temp to keep the burn optimal. Simply put, hotter intake charges burn quicker and cooler charges burn slower. By zeroing out this table, you may end up with an acceptable total timing at warm temps, but not enough additional correction as they get REALLY hot. Conversely, you may also be leaving potential safe timing on the table when temps are cooler, losing efficiency. It has been my experience that the factory values do not require very much adjustment relative to IAT if you have the right values in the high octane table and other adders. (I actually like to populate the AFR timing table on older LS1s where they were zero from the factory too)