Kingtal0n

ok heres the latest deal with this twin turbo project. I got my air filters on, finnaly. I basically stuck them right to the front of the turbos, well one has a pipe running down to the charcoal canister tray, the other sticks to the front of the turbo. all of my pipe is aluminized steel (exhaust tube) .085" thick.

I start the car, there is a MAT temp sensor in the plenum of the stealthram. It reads like 90* or whatever the outside temp is outside.

I let it warm up a little, till i can hear the turbos whistle through the exhaust, and by that time the temps are 120* somewhat steady. I take it out for a drive, and give it 3/4 Throttle. I see 8PSI of boost in the plenum. air temps BARELLY move, maybe 121* MAX.

First question here, what does that mean? I mean, with 8PSI of boost, shouldnt the temps rise at least 20-30*? My intercoolers couldnt be THAT good... right?

ok so i keep driving... NORMAL driving. like barelly any boost, but the temps keep going UP. UP and UP. finnaly i park, and they are like 165*!! I get out, open the hood, and i cant even touch the plastic part of the air cleaner. i cant even touch the plenum. I get back in, temps STILL going up! by the time i shut the car off, MAT temps were 180*F, just sitting there idling. WHAT IS THE DEAL? I took it back out, and got into boost, again 8-10PSI, and the temps DROPPED back down 160*, and wouldve kept dropping im sure had i kept going. WHAT is going on here? Do you think the air filters are just in a really crappy place (right on turbo) so the air they suck up is super-heated already? or... !!!!

SATURN5

Which MAT sensor are you using? If its the all brass MAT, the response time it really slow..

Look for one of the open ended MAT's (V6 IIRC), they have a better response.

BW

Dustin Mustangs

iTrader: (1)

That seems just about opposite of what I would expect. Maybe not enough oil is getting to the turbos at idle. I know my f-body has a dramatic decrease in oil pressure at idle.

I don't supose you have an EGT gauge do you?

Guido

I dont know man. Sounds odd to me. I have never had any experience on and off the throttle like that to know. And never air to air either.

Kingtal0n

<b> Which MAT sensor are you using? If its the all brass MAT, the response time it really slow..
</b>

Oh no, the response time is great. the second you hit the throttle you see the air temp drop in the ECU, real time.

<b>That seems just about opposite of what I would expect. Maybe not enough oil is getting to the turbos at idle. I know my f-body has a dramatic decrease in oil pressure at idle. </b>

Well at idle the turbos see 12PSI of oil pressure. I am told they shouldnt actually "see" the pressure, there should be a restriction somewhere to limit flow (avoid blowing seals) but i figure with #4AN line, both turbos feed from the back of the block, and #8 returns, there really shouldnt be a problem with oil pressure blowing seals. they dont smoke, so its not backing up.

Today i just started the car and ran it at idle. the temp stabilized about 130*F in the intake, after the car idled for about 5 minutes. after about 5 more minutes of light driving, it was around 160*F.

83 Crossfire TA

iTrader: (2)

Heat soak.

You’ve got all sorts of big metal parts under the hood that get hot when you run the car hard, but while you’re running the car hard you’re getting a lot of air flow which cools the actual intake down. Stop the car, and you’ve got all that exhaust plumbing hot and no airflow, everything under the hood starts absorbing heat…

Kingtal0n

thanks crossfire, ive sort of expected the same thing. whats the cure? Im thinking of routing the air filters somewhere they can get fresh air, instead of under-hood air. ideas here?

also, if i replaced the intake tubing with aluminum, would it make a BIG difference? I dont plan on it, but if it will help ALOT ill consider it.

What if i wrapped the downpipe / manifolds with header wrap? I KNOW it will cool the engine bay down, but do i risk warping the living crap out of my manifolds or downpipe? thats all im worried about there.

and im considering cutting a few louvers in the hood over the master cylinder to direct airflow there, allowing it to also circulate under the hood to keep temps down. a better alternative would be a cowl hood of course, I HAVE one that would be perfect, BUT... it would ruin the awsome sleeper effect I have going with the car. I just dont know... well, i suppose its not such a bad idea after all... sigh* and to think i was about to put the stock rims back on tommarow... complete the sleeper effect and all...

83 Crossfire TA

iTrader: (2)

Anything to keep the heat out of the engine bay, whether heat wrap, heat shields or more airflow, that’s where your heat soak is coming from. Getting the filters the coolest possible air will help, but only while you’re actually moving, and that is not where you’ve got the problem. As it stands, aluminum intake side ducting would make it worse (it absorbs heat faster)

Damon

You know, Crossfire raises a good point. In a STOCK TPI engine (with the MAT sensor screwed into the bottom of the plenum) I did some pretty extensive observarion/testing and it acted similarly to what you are seeing. Hot while driving easy, cooled down when you laid into the throttle. Didn't do it to the extent yours is, but similar behavior. It was definitely heat soak causing the readings we were seeing. No way the air going into the cylinders was actually that hot- the sensor was just having heat radiated into it by the hot metal all around it. Moving the MAT to the air filter box gave much more consistent readings and engine performance.

However, I'm not sure if doing something like that would be beneficial or even wise on a turbocharged engine.

fb305svs

should consider heat shields, having everything ceramic coated, and definately relocate the filters - the cooler the air in the better, and with cooler air is, the quicker temps will drop...


i think getting those headers/ turbo housings, and all that fun stuff coated will help a lot more than you might think!

biggtime

Get everything under your hood ceramic coated inside and out. You will be suprised how much cooler it gets under there.
On my g body i have my air intake going thru the battery tray and under the car in front of the tire. I don't know if you can do it but it's worth a look.

Don't move your MAT to the airbox. the computer needs to know how hot the air is in the plenum. On stock NA cars moving it will fatten the mixture up so it is a good mod but not on supercharged.

Kingtal0n

Well for experimentation purposes I put the cowl hood on the car, and all day during boost and normal driving the temps rarelly went over 130*F. Im heat wrapping the downpipes and manifolds this weekend or next, more info later.

Kingtal0n

Here is a DATALOG. this is after a 50 miles drive, so temps stabilize in the 140-150* area. I step on it here from a dead stop, and as you can see, the MAT temps DROP under boost!