[cjperformance]

Im close to having things "dialed in" on my now year long effort to learn and tune without a shop and/or dyno. All due credit to this board as my primary source of info for where i am now though. Anyway, the last few weeks after getting the dragy, I have been able to get better and better performance, now that i have a non-seat-of-pants measuring tool.

The other day i noticed my IAT and MAT were very high after a long pull. The ambient was 90 deg F. IAT started around 120 F and I did a long 3rd through end of 4th gear pull. IAT rose during the run up through 135, 145, 155... engine started pulling timing at 140-150 degrees due to the IAT vs timing tables... was down 2 degrees of timing at the top of 4th gear.

After i let off the IAT still continued to rise for about 1 second to about 170 before starting to cool back down.

I get that less timing is needed at higher temps, and to protect the motor. And higher temps are the result of shift rpm increase and subsequent boost pressure increase. Im just wondering what others have seen. Im wondering if i just shouldnt push things on hot days, or maybe i just shouldnt worry about it and let the computer do its job of backing down timing.

There was no knock and according to dragy, there was no performance loss compared to a cooler day's run (with a slightly different tune) so backing down the timing according to IATs seems to be a working strategy.

I double checked that the intercooler wasnt obstructed or anything like that. I honestly just havent driven it in weather this hot before at my current tune/performance level. Everything else as far as the log was spot on. Incredible MAF lbs/min for the heat, great cyl airmass, EQR was absolutely spot on at .82 with 53% eth. Boost was peaking at 8.75 lbs.

I feel really good about the tune right now, just a bit concerned what IATs would do if i had an even longer pull. The intercooler is fairly obstructed by the front license plate (required in my area), and the front crash bar. Theres not really a whole lot i can think of to do to make that better. The pc intake is the rear facing one that sucks in from next to the engine. IATs started in the 120s... 30 deg above ambient already... Any thoughts?

[Crazy Drywall Guy]

I'm still in the tuning process but I noticed the exact same thing. On 90 degree days it will pull 2 degrees of timing at Wot. The tuner said it's perfectly normal with high IAT temps and that's what it's supposed to do. After my last experience with a tuner I question everything now lol

[Joshinator99]

Out of curiosity, what intercooler are you running? Those IATs you’re seeing seem high to me…? Or maybe that’s why so many Procharger guys run meth on their rig.

[KingLT1]

That's normal for a P1 unit. I posted screen shots last summer comparing a P1x to my Whipple. Both start around 115-120 MAT then by the top of 4th gear mine is around 130 but the P1x is 154. Peak boost was similar between the 2.

Either way if you are on E, then you shouldn't need to pull any timing until 154 degrees. You can also use a little meth injection for cooling...or move up to a D1x.

Timing pull is costing you power. I believe the "more heat needs less timing" was taken out of context. It does to keep detonation at bay but it doesn't make the same amount of power as cooler cylinder temps and more timing. There is a range you want to be in for peak combustion efficiency.

[cjperformance]

Originally Posted by Crazy Drywall Guy

I'm still in the tuning process but I noticed the exact same thing. On 90 degree days it will pull 2 degrees of timing at Wot. The tuner said it's perfectly normal with high IAT temps and that's what it's supposed to do. After my last experience with a tuner I question everything now lol

Thanks for the input. If im going to nuke my engine, i want to be the one to do it.

[cjperformance]

Originally Posted by Joshinator99

Out of curiosity, what intercooler are you running? Those IATs you’re seeing seem high to me…? Or maybe that’s why so many Procharger guys run meth on their rig.

Stage 2... again its large but i feel like a lot of its potential is lost because of its placement.

[cjperformance]

Originally Posted by KingLT1

That's normal for a P1 unit. I posted screen shots last summer comparing a P1x to my Whipple. Both start around 115-120 MAT then by the top of 4th gear mine is around 130 but the P1x is 154. Peak boost was similar between the 2.

Either way if you are on E, then you shouldn't need to pull any timing until 154 degrees. You can also use a little meth injection for cooling...or move up to a D1x.

Timing pull is costing you power. I believe the "more heat needs less timing" was taken out of context. It does to keep detonation at bay but it doesn't make the same amount of power as cooler cylinder temps and more timing. There is a range you want to be in for peak combustion efficiency.

Great info as always. Thank you. Any info on what the temp differences would be between a P1X and D1X given everything else the same?

I think what ill do is just see what it does on the track this year. Ill be able to take logs the next time out, so should get some good data, and make a decision from there if its not doing what i want.

What does meth for cooling look like vs meth for fueling? Is it just amount? Ive heard so many negative things about meth on stock LT1 bottom end.

[LT1ornothing]

Originally Posted by cjperformance

Great info as always. Thank you. Any info on what the temp differences would be between a P1X and D1X given everything else the same?

I think what ill do is just see what it does on the track this year. Ill be able to take logs the next time out, so should get some good data, and make a decision from there if its not doing what i want.

What does meth for cooling look like vs meth for fueling? Is it just amount? Ive heard so many negative things about meth on stock LT1 bottom end.

The problem seems to be meth distribution from nozzle setups, especially when combined with the use of a dry intake manifold such as the LT1. The cylinders in the rear of the engine do not receive equal amounts of meth as the others do. Direct port meth injection seems like a safer solution, but at this point, you may as well do a secondary fuel port injection system to aid the direct injection system. Port injected e85 will probably pull just as much heat out of the cylinders as meth would.

[Sillysspeed]

The good news is that e85 has a great cooling effect in the cylinder that iat can’t measure. But It goes without saying though that the lower it is (iat) the better. I haven’t even got my new car yet but I had noticed in photos the crash bar covering a good bit of the intercooler. I’ll probably pick up an extra one (crash bar) and do some 3-5” holes in it to let more air thru. Can hurt and will keep most of the strength in the crash bar.

[cjperformance]

I would think the goal is not to cool the cyl, but increase the density of the intake charge. Think of the difference on a 60 degree day vs 90 degree day, cooler air is denser air.

Maybe that can still happen all the way down at the cyl, or right before, but i would think the further upstream the better. I really have no idea.... just thought the idea of meth in this case was to densify the intake charge.

[95 imp]

As King said... meth injection for cooling the intake temps, or distilled water sprayed on the exterior of the intercooler will help keep temps down.

A cool, dense charge is better for power.

The game is pretty much over when the air charge is in the cylinder. A little extra cooling is icing on the cake. You can't really pull it down much in the cylinder. Limited amount of time/limited volume of fuel.

The intercooler is the place for removing heat.

[LT1ornothing]

Originally Posted by 95 imp

As King said... meth injection for cooling the intake temps, or distilled water sprayed on the exterior of the intercooler will help keep temps down.

A cool, dense charge is better for power.

The game is pretty much over when the air charge is in the cylinder. A little extra cooling is icing on the cake. You can't really pull it down much in the cylinder. Limited amount of time/limited volume of fuel.

The intercooler is the place for removing heat.

Really makes you think how advantageous a wet micro shot of nitrous would be on a hot summer day with any blower application. Even aiming your nitrous purge at the air to air intercooler just before your wide open throttle run would dramatically positively affect the pull on a hot day.

[Sillysspeed]

If you guys think that is high iat’s and fuels don’t cool in the cylinder you should see m1 iat’s!!! I’ll have to look back at some of my old data logs. Pretty sure it was 250-300deg iat’s.

[SC88]

Iat's seem normal for what your describing. I vote to save the racing for the night time or cooler days if possible. Nothing good ever comes from racing on a hot humid day lol.