Summer heat... how bad does it affect your ride?

[Calan]

The first 10-15 minutes that I drive my car in the afternoon heat (95-100*), it runs pretty good... after that I start getting knock. I'm running around 15-17 psi boost on pump (91 or 93.. doesn't make a lot of difference, although my chip is set for 91). At night and early mornings, it runs strong for the most part, but still knocks a bit after a couple of pulls (heat soak?).

I've tried running richer, leaner, with meth/water, just water, etc. I've also moved my air filter out of the engine bay completely and to a front fresh air intake, and wrapped my IC pipes (except for the j-pipe and lower).

I was thinking it was just IAT temps, but with the IC output pipes wrapped and the air coming from outside the bay, I dunno. The TB elbow still feels hot though, although it could be from heat transfer during the time I'm getting out of the car and popping the hood. Even if it is still IAT temps, shouldn't I be able to dial it out with water injection?

On another semi-related note, last night I hacked the stock radiator ducting so it would fit with my FMIC, and put it back in. The car is now actually running a bit hotter if anything. I've got a lower air damn sending a bit of air up into the radiator which helps by maybe 5*. I'm also running a 20-80 mix with water wetter and dual fans, but the temps skyrocket to around 230 anytime I turn the a/c on. With it off, they are around 206-213.

It's frustrating... anyone else having to deal with this?

 

[Calan]

@ NightSpeed

I agree on the AFPR point. Since the car isn't leaning out at WOT, I'm pretty sure I have good fuel support unless it is glitching. Also, I have the same DP/EvoIII O2 issue as you, but I've modified it so it isn't (shouldn't be) rattling... (were you in the other thread?)

Another question...

Let's say I'm cruising along at 3000 RPM in 3rd, and I nail it. How long should it take for the AFR to drop from my closed-loop value of 14.9 to whatever I'm tuned for at WOT? It usually falls to 10.5-11 (ideally), but takes a second or two to get there before leveling out. I've been assuming this is logger lag or just a normal response.

I'm leaning more and more towards FMIC heatsoak, although I don't know why unless it's just the underhood temps causing the J-pipe and lower IC pipe to stay really hot. I have both heat shields on, but those pipes still get really warm down there. See #24 of this thread also:

http://www.dsmtuners.com/forums/showthread.php?t=256317

BTW - On the way to work this early afternoon, I was able to get a steady 3rd gear pull with no knock. With all 5 eyes on the road and logger , I was seeing about 18-19psi (after some small creep), 10.7 AFR, and 16* timing... using straight water injection coming on at around 12 PSI. But again, it's much cooler today and that pull might have been a fluke. I didn't get a chance for another one afterwards.

 

[nightspeed87]

@ NightSpeed

I agree on the AFPR point. Since the car isn't leaning out at WOT, I'm pretty sure I have good fuel support. Also, I have the same DP/EvoIII O2 issue as you, but I've modified it so it isn't (shouldn't be) rattling... (were you in the other thread?)

Another question...

Let's say I'm cruising along at 3000 RPM in 3rd, and I nail it. How long should it take for the AFR to drop from my closed value of 14.9 to whatever I'm tuned for at WOT? It usually falls to 10.5-11 (ideally), but takes a second or two to get there before leveling out. I've been assuming this is logger lag or just a normal response.

I'm leaning more and more towards FMIC heatsoak, although I don't know why unless it's just the underhood temps causing the J-pipe and lower IC pipe to stay really hot. I have both heat shields on, but those pipes still get really warm down there. See #24 of this thread also:

http://www.dsmtuners.com/forums/showthread.php?t=256317

It all depends about how much throttle your giving it in response to how fast it leans out.
By the time you reach 3/4th throttle it should be near or at what your wot afr should be at.
The heat soak issue is more prevalent than one would assume thus is why I dont go into boost or full throttle during the heat of the day unless its just not a hot day. Hell I dont see more than 4k partial throttle rpms during a hot day. Most of my spirited driving is at night, I only cruise to work and school during day time and dont have time or even bother paying attention to anything performance related during those time so I cant tell you how pronounced the difference of day time/ night time driving is.
Do some logs at night when its nice and cool and see if you still have knock...If not, then we all know heat soak is the issue.
From previous threads Ive read, tips on dealing with heat soak ( which worked for me )

1.) making a sheet metal dam to keep air going into the fmic/ and radiator
2.) wire the fans to stay on all the time
3.) do hood venting to release hot air out of the enginebay which proves very effective.

Also what works for me, i just run straight distilled water with water wetter.
Your coolant temps are a little high... Youve already lost maybe 2degs of timing just from those temps i believe as the engine starts pulling 1deg above 206.
Also check to make sure your logger is correctly working, AND your knock sensor. Ive had issues with a faulty knocksensor on my gst that would randomly show knock whenever it felt like it.

p/s
Be positive its not boost leaks as that will make the turbo work harder inducing hotter air to the engine.

 

[Calan]

1.) making a sheet metal dam to keep air going into the fmic/ and radiator

Done

2.) wire the fans to stay on all the time

Done

3.) do hood venting to release hot air out of the enginebay which proves very effective.

Does removing the weather strip at the back count? (That did actually drop underhood temps a bit, although I think that may be a positive pressure area and shouldn't theoretically work)

Ive had issues with a faulty logger on my gst that would randomly show knock whenever it felt like it.

Knock sensor is new, and my reprogrammed stock "knock" boost gauge matches the logger.

Boost leaks are good (#10 above)

Thanks for all the suggestions and feedback

 

[nightspeed87]

Does removing the weather strip at the back count? (That did actually drop underhood temps a bit, although I think that may be a positive pressure area and shouldn't theoretically work)

Thanks for all the suggestions and feedback

Funny ive actually thought of removing that back there but i didnt think it would leave an large enough gap when the hood was closed to release any air...
Hell I may just try it just for kicks since now that I know someone else did it too ...

 

[Calan]

Yeah... I've heard some say it works, and others say it actually hurts because of the pressure differential. But if I've learned anything about what works on a particular DSM, it's WHO THE HELL KNOWS... TRY IT...

Actually mine was ripped and about to fall out anyway... I just helped it along

 

[nightspeed87]

Yeah... I've heard some say it works, and others say it actually hurts because of the pressure differential. But if I've learned anything about what works on a particular DSM, it's WHO THE HELL KNOWS... TRY IT...

Actually mine was ripped and about to fall out anyway... I just helped it along

I dont follow the pressure differential part most of the air in the engine bay while driving tries to go under the car due to being the only escape, but heat rises so theoretically it would make sense that it could vent the heat out and provide an addition escape route depending how big the gap is from taking that out.

One more suggestion for your set up is what thermostat do you run?
I run the 180 and it somewhat helps keep the engine temps lower; but the only negative
effect of running a 180 on a 1g is that the engine takes longer to leave learning mode and go closed loop ( worse gas milage typically during warm up period. )
And in cold winter times it may never leave open loop during cruising...
I run a chip also, my friend burns them for me with is ROM tuning software
but im going to ask Jeff at keydiver if he could lower the 1gs 190deg closed loop switch over point to 180 so that i wont ever run colder than the ecu based operational temps ( tuning wise. )

 

[Calan]

One more suggestion for your set up is what thermostat do you run?

Which one haven't I run?

I tried new stock 192*, stock drilled, stock completely cored, 180*, and 180 drilled.

I think right now I'm on a new 180*... and I like the chip idea. Might give Jeff a shout myself.

****

The pressure issue stems from turbulence at the the area where the windshield and hood meet. Think of old muscle cars with cowl induction. They take advantage of this effect to actually suck air INTO the engine compartment from this area.

 

[nightspeed87]

Which one haven't I run?

I tried new stock 192*, stock drilled, stock completely cored, 180*, and 180 drilled.

I think right now I'm on a new 180*... and I like the chip idea. Might give Jeff a shout myself.

Hmm.. You seem to have good mods, good dsm knowledge, and a lot of hands on
tests with getting your car the way you want it, therefore I cant figure out why you are having these knock problems. May want to dig deeper into your set up to see if you have a glitch somewhere... But doing all possible to lower under hood temps is still good practice on turbo charged vehicles whether knocking or not. Wish i could help more, but i know nothing of gm maf-t set ups , and im running out of ammo.

p/s o you never answered one of my main questions, what are your timing maps like
and what compression do you run on your 1g?

 

[nightspeed87]

Well im about to get offline but reason I was asking about your compression is because the 1g timing maps are too aggressive for any significant compression increase without altering the timing maps...

Example, a year ago I had put in 2g pistons on my 1g gst.
Well it would knock at even a simple 15psi from the 14b were as on the 1g pistons it wouldnt. This was both with an 11.1 air fuel ratio...
Running the 2g pistons required me to run 2g timing maps to not see any knock and this is why
I urge ppl to get dsmlink or a chip tune vs getting a ### safc in which you cant change timing maps for these situations, safc only raises timing with larger inj which will make matters worse...
Anyways back on topic, the 2g maps are much less aggressive...
So if you are knocking due to raised compression while running 1g maps this is why,
and no matter how big a front mount or how rich you run it will still knock after x amount of psi due to the heating being internal and not from intake air temp.
If you have higher than stock compression id recommend getting your chip reburned for 2g type maps ( you dont have to lower your max timing adv just the style of map, 1g maps spike and peak more. ) 2g maps are easier to deal with as far as tuning knock. Jayrolla on this site had the same issues with the 2g piston swap and ive even spoken with someone before that had the issue on the ross 8:3.1 pistons w/ 1g maps.
My gst is back on 1g pistons now and I can get more timing out of it, my 1g awd is still stock block also and I get away with 19deg with 19psi 11.1 afr, JRC fmic, 93 octane,n/t 47.6 fpr, 850cc FICs, walbro hp 190lph, Evo3 16g, 2g mass, chipped eprom, no knock in 3rd or 4th gear Wot pulls.

If this is completely irrelevant to your issue then excuse this ramble but the 2g maps may benefit you still.
Just thought id throw this in before i signed out... Good luck.

 

[Calan]

I thought about this a while back, but kind of decided that I probably have 1G pistons...

The motor was rebuilt before I bought the car, and there are no receipts or anything available as to what exactly was done. I did manage to get hold of the shop that did it though, and they said they didn't remember that specific engine, but their normal practice would have been to bore it slightly if needed and use stock pistons.

Shortly after that, I ran a compression test and had numbers that led me to believe it was indeed 1G stuffed. But I ran one since then with lower numbers, so now I'm not completely sure. I need to do an actual measurement test to find out though.

The 2G maps might be an idea though... if they would work even for the 1G's, it might be worth it to give that a try.

Thanks for all the ideas RJ

 

[UMR98GSX]

It got so hot the other day that my fuel pump relay for the rewire melted under the hood.