what are your air temps in the manifold?

[Six_Silver]

I am seeing 140 degrees at the end of the run with a t-66 and v4 intercooler. I noticed in the new gmhtp with the turbo test (Luis Lopez and Cal Hartline) that the temps were in the mid 70's. What kind of temps are you guys seeing and what turbo/intercooler are you running? And also how much effect on et does the air temp have (ie going from 140 degrees to 70)?

ps I didnt post this in general tech because the stock ECU guys dont have the sensor after the turbo.

 

[TurboTR]

Well the 1st question is- what temps are you starting the run at? I'd guess you have an open filter near the radiator, and that your starting MAT is about 100 deg?

The MAT has a big effect on air density and thus hp...

TurboTR

 

[bruce]

Running with no intercooler, the MAT was generally about 20dF less then the coolant temp.. It was common to see that MATs exceed 200dF.

Using alky injection, I was able to see the MAT drop to about 80dF and then slowly increase.

Using Cotton's Front Mount, I generally run about 20dF above ambient air temps.. While initially when *into it* the temps raise some, but as my speed increases they stabilize, and depending on the weather, can start dropping.

For every dF you drop the MAT, you drop the EGT by the same amount.

140dF to 70dF will let you run less fuel and more timing.

BTW, I'm running the stock ecm, and moved my MAT sensor so that it is really a MAT sensor.

Here's my MAT fuel correction table from when I run the syclone ecm. You can see how it leans out at about 71-80dC (ie when the low end aromatics begin to aromacate <G>). Then at the higher temps the extra fuel is needed for addition in cylinder cooling.

Base Pulse Inverse Air Temp vs ADMAT (ACSP Sensor)
FCB 175 ; Hot
FCB 165 ; 136
FCB 155 ; 107
FCB 149 ; 91
FCB 147 ; 80
FCB 147 ; 71
FCB 149 ; 63
FCB 153 ; 56
FCB 165 ; 49
FCB 169 ; 43
FCB 175 ; 37
FCB 177 ; 30
FCB 179 ; 23
FCB 185 ; 15
FCB 192 ; 6
FCB 192 ; -8
FCB 192 ; Cold

 

[Razor]

Ambient at 26 PSI through the traps.

 

[TurboTR]

Well a 30-40 deg MAT rise during a pass is not unusual with a typical a/a fm IC. So if you are starting with the system heat soaked to around 100-110 deg or so, then you would expect to see ~ 140 deg at the end. If you started out with MAT of near ambient or say ~ 70, you'd finish with 100-110. A reduction in MAT of about 35 deg over the whole pass in this temp range implies about a 6.3% increase in air density (and potential hp). On a 650 hp engine that's ~ 40 hp.

Razor's (and others) alcy system results vs the stock IC alone seem to support this sort of calculation. If you decrease the MAT from say 140 deg average during a pass to about 80 deg average let's call it, then you increase the air density about 11%. On a 400 hp engine that's about 45 hp. I think that's in the neighborhood of the speed gains that people are seeing with spraying alot of alcy. You might expect that to be reduced a bit from actual gains, since all that vaporized fuel has to take up some space that could have been occupied by air But it seems we are close to real world for an e-racer type approximation at least lol

TurboTR

 

[TurboTR]

Whoops, I meant "you might expect the real world gains to be reduced slightly from that"...

TurboTR

 

[bobc455]

Originally posted by Razor
Ambient at 26 PSI through the traps.

Are you running a liquid-air IC?

I have a hard time believeing that any air-air IC can reduce the temperature back down to exactly ambient.

-Bob C.

 

[TurboTR]

He's running an internal liquid "IC"

TurboTR

 

[Razor]

Lets say my motor has a bad drinking habit

 

[Six_Silver]

Originally posted by TurboTR
Well the 1st question is- what temps are you starting the run at? I'd guess you have an open filter near the radiator, and that your starting MAT is about 100 deg?

The MAT has a big effect on air density and thus hp...

TurboTR

Yea the runs start around 90 and actually end up closer to 150 at the end.

For those of you who replied, you didn't state what turbo/intercooler combo you are running. I am guessing that you are all running a fmic??

 

[Hawaiian Turbo]

I'm running a PTE FM with a PT-70. Starting with 130 and went up to 160, 3 degrees a second. I since routed my turbo inlet from the front of the bumper, instead of the engine bay area. I think that will help alot.

 

[S2V6RACER]

I saw 105 F on launch and 155 through the traps at BG with a PTE front mount/70GTQ turbo. I have a hard time believing temps will fall lower than start temps at the end of the run with a air/air setup.

 

[Razor]

I run a FM.

FWIW Cal Hartline with his V3 will see 140's at 35 PSI through the traps.

He said he was getting 170's with his old PTE FM.

 

[Hawaiian Turbo]

Wow... a 30 degree diff. I didn't have a chance to see if the air inlet rerouting made a diff or not.

 

[azgn]

I do not believe input air temp to the turbo makes a bit of difference...in fact, any bends or extended tubing lengths would be a net disadvantage on a big turbo

any advantage from cooler ambient will be gained from the IC

that said.....couple of runs at the track yesterday......Mat temps went from 90* to 126* and from 80* to 115* with a V4 and GT70 turbo (10.6@126 mph passes at 25 lbs of boost..filter in engine compartment...car weighs 3700+)

the very first run started at 73* and went to 99*

as the day goes on, starting and ending temps go up as does the incremental change....about the smallest change I see is 25* or so over beginning of the run temps....more typically would be +30-40*

I don't know of any air to air that will lower the temp over the course of a WOT run and I doubt such an animal exists.....prolly the more efficient IC's or air to water types would have a smaller change over ambient, but always positive temp increases

 

[INTMD8]

Turbo inlet air temps will make a hell of a difference on intake manifold air temps, especially if you're nearing the limits of the intercooler.

Run your turbo inlet tube from inside the fender and log IAT's, than let it take air from the radiator and log the IAT's.

The temperature differential will remain the same if the IC doesn't get heat soaked, but the IAT's will always be higher when the turbo inlet temp is higher.

 

[Razor]

Only when the car is stationary. Once your going 80+ mph down the track.. there is no temp difference. Since all the hot under hood air is getting sucked out.

I'm with AZGN, only thing I gained from running a filter under the car was it got clogged faster.

 

[azgn]

INTMD8, I'll do just that next time out and let you know.......I have a "cold air duct" (4" tubing behind the air dam that blows on the underhood air filter behind the headlite)

I'll hook the input pipe direct to that and see what happens (no filter) but it'll entail a couple of bends and more tubing...my guess is no gain or slower

 

[TurboTR]

There is a subtantial difference for the whole run with a good cold air pickup. I mean a good one that always only gets cool air, not just a path to outside air directed at the filter. The important point is to not heat soak the system to the temp of the underhood air while waiting before the run. If you pick up only cold air while idling in the lanes, the whole system will start at about ambient temp because the IC has been cooled from the inside out basically by the ambient air. If it's say ~ 70 deg out, you'll start (and end) the run some 30 deg cooler than if you start with IAT at ~ 100 deg, like many filter near the radiator setups do. On a 700 hp mill that's about 35 hp worth of air density increase during the pass, which is on the same order as choosing an fm IC vs a good stock loc IC in the first place. I'd call that pretty signiifcant. I have log files from my own car showing what I've described. On mine the 14" K&N cone filter was totally enclosed, and the duct feeding it was 5" dia. The pickup was a custom plastic molded piece at the front lower corner of the car. Molded by Frank Fertita in San Antonio, who was also going to do some of the shrouds for CAS back in the day...

Plus, FWIW, last time my friend ran his low 11's/high 10's car with a PTE fm on it, in some unsually cool night air (for us), his did show a substantial drop in IAT during the 1st half of the run or so, Then IAT leveled off and started moved up from there. He has no cold air pickup and was leaving the line around 100 deg. He does have a FAST so we have logfiles that show this too if anyone cares. FWIW. YMMV.

TurboTR

 

[Hawaiian Turbo]

I'm curious to see your results Woody. I would think it would bring the IAT down versus drawing in under hood hot air.