EGT problems at 26 psi

[mertdastan]

On the Euro version BMW M3 I have problems with the EGT. Exhaust gas temperature increases at the end of the 4th gear on the highway to 1650 F.

Boost is set at 26 psi.

Turbocharger outlet 120 C.

Ambient temp 14 C.

Intercooler outlet 14 C.
The turbocharger seems to be efficient.

Air fuel ratio is 12,8:1.

I cannot keep on WOT in 5th gear as the pistons would melt above 1650 F.

I was intending to measure the turbo backpressure vs. intake pressure. But the gauge that must measure turbine backpressure comitted suicide at 1650 F

Does the 12,8:1 AFR sound lean?

Fuel system:
A- 6 injectors 1,000 cc But cannot be controlled with the BMW ECU. Stock ECU is designed to run with high resistance =saturated type injectors. We have put resistors or /and transistors between the ECU and injectors to enable the ECU to drive the peak and hold 1,000 cc injectors. No success.
B- 6 injectors 440 cc each. Run at 150 psi fuel pressure. In addtion a 300 cc extra injector. Dont say the fuel pressure is too high. Moreover the additional injectors added fuel will not be shared equally by the cylinders. I know but I could not control the peak and hold injectors. They are on the shelf.

Have found 690 cc injectors as saturated and may purchase them.
Ant solution to run peak and hold injectors on a saturated ECU will be appreciated.

The dump pipe is 3,1" and after the dump pipe 2 straight pipes each with 2,5 " diameter go till the rear muffler. No catalytic converters. No resonators.
Wastegate 45 mm. Wastegate outlet is a 1,6" separate pipe.

The dump pipe seems to be restrictive but we had space problems and kept the diameter of the dump pipe at 3,1".


Should I try increasing the diameter of the dump pipe and the piping that goes from the dump pipe till the muffler?

Or get a bigger wastegate? And increase wastegate diameter to 3"?

I cannot increase boost further.
Would like to try 32 psi. But EGT stops me.

Thanx.
MERT

[josh@werksgroup]

12.8 A/F is great for power but not longevity. I’ve found time and time again leaner is meaner but what counts is thermal stability. The higher the gear the more load you are working against and the EGTs will rise. For the power levels you are running I wouldn’t think twice about a stand alone FI system that will handle low impedance injectors. How much overall ignition timing are you running and what has been done to the motor?

The wastegate isn’t the source of your EGT woes. And a 3” downpipe is plenty large..

[mertdastan]

Hi John,

We have a forged piston, stock con rod bottom end.

I dialed in 10 degrees of advance over the stock M3 ignition.

Will try to use peak and holds soon.

MERT

[RAiMA]

Is the intercooler outlet temps at 14 C on full boost with ambient temps at 14 C?

[E30GoDz]

i bet some water/alcohol injection would lower the EGT's a bit...with that high of boost you may even consider a water/air intercooler.

[LordofMpower]

Originally posted by E30GoDz
i bet some water/alcohol injection would lower the EGT's a bit...with that high of boost you may even consider a water/air intercooler.

I would definitely consider doing some water/alcohol injection it helps a lot and adds a safety area as well. however unless its a strip car only I wouldn’t suggest and air to water intercooler the water will heat up quite quickly under hard 5th and 6th pulls on the highway and 12.8 is lean for that kind of boost levels, makes excellent power but I would tune for 12.2-12.5 many of the new factory turbo cars (evo8's sti's) are running mid to high 10's A/F

My coworker Bob runs water/ alcohol injection on his miata
http://www.cardomain.com/id/p1auto

[Kevin]

Ceramic coat the pistons and manifold

[b0rf]

You run the stock ECU????

[mertdastan]

Stock ECU is being controlled by a Piggyback System called Unichip.


Ceramic coating will insulate heat and increase heat in the combustion chamber, not a good idea, sorry.

[b0rf]

Aren't you a bit restricted by the relatively ancient Unichip?

Considered Tec-3?

Or UTEC?

[josh@werksgroup]

Thermal barrier coatings may increase the temps in the exhaust manifold but it will decrease the heat on the piston crown and rings. The motor will "see" lower temps. Increasing the thermal efficiency of the motor is a good thing. You really need to change over to stand alone and get away from bandaid solutions. For the amount of power you are pushing unichip is silly.

[Igor328]

Maybe you have an injector failure,the fuel pressure is too high !!!!, a safety fuel pressure to run is up to 75 psi.....I thing these injectors can't feed your engine at WOT....you should try a lambda meter to see if its lean fuel problem...

[MacDubois]

I can't add anything new, but stand alone is the way to go.

And ceramic coated exhaust is the way to go, except that at the temps you're running I can see you frying your turbo, so you would need to ceramic coat the exhaust turbine, and upgrade to a ball bearing turbo, capable of handling the heat(if thats not what you're running already). But heat=energy...sort of, so if you stop losing it to your engine bay, you'll probably produce more power.

But the extra fuel injectors should help the temps, if you increase the AFR, and just because your fuel injectors can run to 150psi doesn't mean they should...the flow patterns could be completely screwed at those pressures...or they could be better, but I doubt that, I just don't know, but there is a reason most injectors aren't run that high.

And ideally a custom fuel rail designed to take advantage of twin injectors would be good, but thats physics way beyond anyone but an extremely accomplished engineer with a flow bench could comprehend.

Oh, and water/methanol injection is rediculously effective for something so cheap.

Oh and get about 6 oil coolers and three more radiators. Okay that might be silly, but the 996 turbo runs 3 radiators, and most race cars with power far below yours have 2 oil coolers (I assume you have a beefy oil cooler and a really nice radiator already, so ignore this)

[mertdastan]

MAc Dubois

Thanx for the write up.

The water and oil temps are excellent.

And the current turbocharger is a ball bearing one.

We found out that exhaust turbine is causing the restriction and purchased a new bigger one.

[dk_]

the guys i've seen running serious drag turbo setups seem to shoot for 12:1 even most of the time...

*shrug* trying a slightly richer tune certainly won't hurt your engine, anyway