EGT's and alcohol

[V6POWER]

I have always tuned my car to run with the highest EGT's (1600-1620) because I thought that I should tune for the leanest mixture. However, I now see that some of you are tuning for EGT's in the the lower 1500 range and you are running well. Should I readjust my tune for a richer mix?

 

[65vette396]

Wow, where is your EGT mounted. If this is just before your turbo, then I have no clue how you don't have a lot of broken parts. Forced induction vehicles need to have the AFR in the 11.7-12.5 range to keep parts happy. This should be in the neighborhood of a 1450-1500 EGT. Leaner breaks parts. Drew

 

[V6POWER]

EGT is mounted just in front of O2 sensor. If my EGT was reading in the 1450-1500 range, I would be extremely rich with O2's in the high 800s.

 

[65vette396]

If that is the case then your chip doesn't have enough timing or the ECU is pulling too much timing. EGT's in the 1600's is not good. You might also have a restriction of some sort. Good luck, Drew

 

[BLACK6PACK]

My car likes egt's in the 1600-1650 range too. Most of the guys that I know that are running alky tune for that range too. Low 1500's and I'm blowing black smoke.

 

[V6POWER]

65vette396---Do you have a T-R? If so, what is your combo and what do you run? What is your EGT?

 

[pacecarta]

i just hooked up my egt recently (SMC -probe at the tubo inlet) and see 1600, no kr ,

was told by a pro with alky (goes by the name of julio ) to shoot for just a little less , nothing really wrong at 1600 just may find it a little faster at 1570s . he recommends 1500s to 1520s
once you get near 1650 or higher kr normally shows its ugly head

waiting for the track to open to tune the new combo in


mods are in sig

 

[V6POWER]

I will try running a little richer (upper 1500s) and see how she runs. Thanks for responses.

 

[65vette396]

Yes, I have a turbo regal. I have had probably 15 over the past few years. I also have a twin turbo supra (for sale as we speak), and a Big block chevy with a T91 turbo in a full size chevy truck. My last T-Type had ported heads, cam, 63 turbo, 55 lb. injectors, streched I/C ATR downpipe with external gate, ect........ It would go through the traps at 1450-1500 with the O2's in the 780's. The supra has a 3.5 in. downpipe, stock twins, front mount, 3.5 in. catback, and boost set to 25 psi. it will go through the traps at 1480-1520 and the wideband is showing 11.9-12.2 the whole pass. The truck has all kinds of **** done to it, and will go through the traps at 1600 degrees, but the egt is only one inch. from the port on the leanest cylinder, this should be in the lower 1500's before the turbo. My current buick, it a Stage II 274 cu. in. with M&A heads, Front mount, 85Lb. injectors, sheet metal intake, 88mm. turbo, solid roller cam, with a DFI running the show. The car was originally built and tuned by Conleys performance plus. It has since undergone some changes, but still runs where Conleys said it should 1450-1500 through the traps with the Wideband showing high 11's low 12's. Maybe my stuff is odball and just runs cool on the hot side, but that is what I have always been told and that is where Conley said the car should run, so that is where I was getting my info. I am sorry if I confused you guys. I was simply trying to help. Drew

 

[V6POWER]

Drew---I am trying to learn about EGTs, so any info is really appreciated. Sounds like you have had quite a lot of experience with turbos.
Question--How can you get the EGT so low but still have the O2's in the 780s? I would like to be able to run richer and safer.

 

[65vette396]

Originally posted by Look Quick
Drew---I am trying to learn about EGTs, so any info is really appreciated. Sounds like you have had quite a lot of experience with turbos.
Question--How can you get the EGT so low but still have the O2's in the 780s? I would like to be able to run richer and safer.

Well, generally it has to do with one of three things. First is the AFR, then the timing, and finally restriction. It seems that your AFR's are where they need to be, although I would verify with a wideband if you have the oppertunity. Next, timing means a great deal, if you don't have enough advance it will run quite a bit hotter on the exhuast side (of course to much and you get knock), and Finally, restriction, I have always run the largest exhuast that I can, the T-Type had ATR's single shot mated to a ATR downpipe, The Truck has a 5 in. downpipe, the Stage powered GN has a 5 inch downpipe, and as stated earlier the Supra has 3.5 " from the turbo's back. I also tend to run the larger hot sides on the turbo's the T-type had a .81 A/R, the Truck has a 1.34 A/R, and the stage motored car has a 1.01 A/R on the hot side. You also need to make sure you try to operate your turbo in it's efficiency range or slightly below there. In other words a stock buick GN hair-dryer is well out of it's efficiency range above 22 psi, but I have seen people running stockers at 28 -30. This does nothing but make more heat. Finally, I always run an external gate on all my turbo cars, that are vented to the atmosphere (I'm a redneck and like the sound for one reason, but I don't know if this helps or not in the EGT's.) However it is less restriction as the waste gases are vented to a separate place than the gases that go through the turbine. I hope that helps, I don't really know what to tell you other than this is how my cars are done and where they run on EGT's. Hope I have helped, Drew

 

[Razor]

Drew is rite on.

But I like the lower 1500's with the AI. My car will pickup 25-29 from 1/8-1/4 MPH at this tune. At 1600 it will pickup 22-23. at 1650-- 20-21 from leaning it out.

Got to throw some fuel into these motors and lite up the mixture..

I think the thing is with a stock computer it gets tricky in the chip tuning. And if you richen it up, the bottom end suffers. So the deal is to get the car lean and mean out the gate and as it goes down the track drop fuel into it to keep the EGT's and AFR in line.

Too much fuel in the bottom end of the track and the car nose dives.

HTH

 

[V6POWER]

Thanks Drew and Razor. I only run the 1/8 mile so are your comments still pertinent? If so, I will increase fp for top end and see if I can lean it out on bottom end using the 'spool fuel' and 'low gear fuel' adjustments in Extender.

 

[Razor]

Originally posted by Look Quick
Thanks Drew and Razor. I only run the 1/8 mile so are your comments still pertinent? If so, I will increase fp for top end and see if I can lean it out on bottom end using the 'spool fuel' and 'low gear fuel' adjustments in Extender.

Exxxxactly

High timing, lean and mean on the bottom.. then pull timing/throw fuel at it to keep your bottle rocket from popping

 

[65vette396]

Razor is going to have to answere that question for you, as I never even look at the EGT's until I get the car into high gear (3rd. for me as all my stuff has a turbo 400). I rely heavily on a wideband more than anything for the entire run. Good luck, Drew

 

[65vette396]

whoops, looks like I got distracted long enough for Razor to beat me too it anyway. Drew

 

[V6POWER]

Should I shoot for high 700s O2's for launch and low gear?

 

[Razor]

Originally posted by Look Quick
Should I shoot for high 700s O2's for launch and low gear?

Man our cars will typically be in the 800's if your using a stock O2 sensor even if your lean. That stock sensor reads a little funky.. and the more heat you throw at it.. the lower it will read.

Easy way to lean out your 1/2 is run a little higher boost in 1/2 becuase of the way our chips drop fuel into the motor

Shhh.. dont tell anyone

 

[V6POWER]

I have noticed before that no matter how lean I go on bottom end, the O2's stay in the low to mid 800 range. Thanks for the explanation.

Did you mean to say to raise 'boost' in 1/2 or 'timing'? I will raise the timing in low gear and see how that works, but I won't tell anyone about that secret.

 

[65vette396]

He was saying to raise the boost, not the timing. BTW, you really need to invest in a good wideband if you can afford it. This makes all the tuning guesswork go away, especially when combined with an EGT, Drew