Exhaust temp's b-4 Turbo?

[Totsabe]

Anyone know what temperature range would be expected at the turbo, from near closed throttle cruising to WOT, using 92 octane pump gas?

Also, what is the best or safest A/F mixture for WOT.

Thanks,

Del

[XcYZ]

I don't know the answers that you're looking for from first hand experience, but from the research and question asking I had done, 11.5:1 AFR was the most common answer I got to that question in regards to a street car. I know when Charley took the Mule on the Power Tour, he put a milder tune in it incase he came across some bad gas or some other unforseen issue, and it was in the high 10:1 AFR.

Oh, BTW, great avatar. Cool story.

[D Rock]

That sounds right on the A/F ratio, that should be a good safe a/f. Not sure about the exhaust temp either.

[Blown353]

Max allowable temp depends on your exhaust valves & hotside wheel. I've seen various turbo mfg's spec max exhaust inlet temps anywhere from 1650-1900F. Inconel exhaust valves will tolerate more heat than stainless. Tuning for about 1650F max EGT is sort of the "standard" to shoot for when it comes to turbo EGT's, temp being measured in the manifold BEFORE the turbo exhaust housing. That being said I've seen where "short use" people (i.e. drag guys) have EGT's in the 2100-2200F range but that's only for a couple seconds at a time. I have a friend with a *nasty* Dodge diesel on nitrous (over 700rwhp, it's way faster than a 7600lb truck should be) that sees 1850-1900F EGT's when he's in pulling competitions (diesel EGT's usually are preferred to be 1050-1100F max...)

If your EGTs are too hot, drop the boost and up the timing... or you may be overly rich and you might have to pull fuel out. Dumping fuel, to a point, cools the mixture & EGT but put too much fuel in and the EGT's will start climbing again as it can't burn completely in the chamber and continues burning in the exhaust port.

For a starting point I'd say 11.0:1 AFR under WOT is good and play with the boost & timing from there to control the max EGT.

[Totsabe]

Thanks guys, for the info.

Just got back from a rolling early spring tune up on the Tahoe. I was concerned with a 1600 degree temp while idling along at highway speed. The advance in the timing map in that area took it down to 1400.

I had put a third wide band in one of the tail pipes to verify the two built in LC1's. A couple of years ago, I burned up some parts going lean, so I am trying to be careful this time around.

WOT was showing a little over 1600 degrees and 12.5:1 on the wide band's. I will have to get on the dyno to finish the tuning. I'm sure the highway patrol would appreciate that too.

The closed loop with the Innovate LC-1 and Tec 3 works like a charm. A/F follows the fuel map perfectly. Right now I have the top of the fuel map set to 12.5:1 for WOT. I will fatten that up before I get it on the dyno.

Thanks again for the help, it is greatly appreciated.............

Del

[projectile]

I have a twin turbo set up (Innovate lm-1 & accel dfi) and I see about 700 degrees at light throttle cruise with afr at 15.1 and timing at 45-49 degrees. This much timing only works with light engine load(high vacuum),but it does help keep the exhaust temps lower from what I have seen.I don't advise that much timing advance, but it works for me. WOT- afr 11.7 and about 1000 degrees ex. temp at 15 psi boost.I have noticed that single turbo engines have higher exhaust temps than twin turbo set ups with the same hp output.I hope this helps.

[Blown353]

Ray, where do you have the TC mounted for your pyrometer and have you checked the pyrometer itself with a signal generator / TC checker from a company such as Fluke? Your EGT's seem *very* low. You'd be surprised how many pyrometers are off a couple hundred degrees right out of the box if you check their calibration with the correct instrument.

[projectile]

Originally Posted by Blown353

Ray, where do you have the TC mounted for your pyrometer and have you checked the pyrometer itself with a signal generator / TC checker from a company such as Fluke? Your EGT's seem *very* low. You'd be surprised how many pyrometers are off a couple hundred degrees right out of the box if you check their calibration with the correct instrument.

I have the tc mounted in the collector about 3 inches before the turbo.No I have not checked the pyrometer itself but i will now.I've also thought that the egt's were quite low.I have never had a sensor overheat code on my innovate wide band, so I questioned one of the techs from "innovate" at last year's sema show.He assured me that the low egt's were o.k., "Just a sign of a very effecient engine".Don't know if I believe that. I've tried 2 different pyro's and only got the same results. Since then i have made a few engine changes, but i will try what you suggested. Can't do much now.Still waiting for my clutch from Mcleod. It's been 4 weeks. When i get the car back together i will do some more testing. I'll let you know what I find. Thanks for the good info.