I have an Heraus Sensor Nite EGT system which can monitor temps from each cylinder with a probe placed in each header near the heads.

I have blown three engines over the last two years and it does not seem to be detonation, just to much heat. The engine is a blown T-Trim at 14lbs. My temp readings under full throttle start out at 2000 deg. and slope down to a reasonalbe 1500 deg. at full boost/high RPM.
I've checked my timming (Accell DFI) which is as high as 39 deg. under vacuume and drops from there to 23 deg under full boost. My A/F seems fine too at between 13.5 and richening to 11.5 at the top end.

I can't fiquer out why things would get so hot down low in the full throttle power band. It actually seems too high at part throttle sometimes getting to 1800 deg on a mid throttle acceleration?

Any one have any ideas?

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10.86 on 94 Octane

[This message has been edited by Bob 96STrimA4 (edited September 12, 2002).]

 

Bob

Sounds like an ugly problem. Sorry but I have no real good guesses. Just sorry to hear of the problem.

 

If you're short on ignition timing the EGT's will go through the roof. Try adding some timing. If you're to low on timing on the dyno the header's will glow. alot of people confuse this with being lean. Add a few degrees and it will quit glowing and the EGT's will go way down.

 

Time for some water injection no?

 

I have a new 396 in now and I'm breaking it in without the blower belt on and the temps are still the same. So I'm not sure if water injection will get to the root of the problem.

What about spark plug gap. I think they are around only 30 thou.

Any "advanced tech" engine guys have an opinion?

 

Bob,

I'm pretty sure Taylormade knows a thing or two about engines etc.

Anywho, there are SOO many possibilities. Ya really have to go from the start Plug Selection/Gap, ignition timing, Rich/Lean condition, Fuel Octane, all can have effects on exhaust temps.

I honestly can't give you any exact things to look at as many of the indicators of problems show Normal/OK conditions.

One things for sure, you shouldn't have gone through as many engines as you have.

Who has taken care of all the DFI tuning?

------------------
Kurtis Tamez
LT4-396.com
97 Z28 LT4-396
94 Firehawk LT1-396
Team NW F-Body

[This message has been edited by KTamez (edited September 13, 2002).]

 

If you e-mail me a univ. file.I'll be glad to take a look at it,I almost bet its in the fuel map/timing map or both if your injectors are sized properly.. also send what bar (1,2,or 3) map sensor your running.

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Joseph Overton (accel/EMIC)
94 TA (new combo new year)
old setup:381,.020 over,5.7 rod,afr heads,comp cam,custom intake,1200 cfm tb,42# inj.,aeromotive pump,DFI,dry nos,th400,strange 12bolt,wolfe rollcage,subframes,lca,s
best n/a 10.95@124.06 1.55 60 ft.
best n20(.065 jet dry) 10.28@128.8 1.43 60ft.
bent torque arm on launch

 

Have you flow matched the injectors?

 

A couple ideas....

First test the egt gauge on another car or test another egt gauge on yours.....

I suspect its real.....and probably correct...

HAs the cam been the same in all these engines? and or the timing chain set?

Was the cam degreed ?

I ask because it sounds like its opening the exhuast valve too soon....or the duration is grossly long......

I know that some timing chains sets were miss marked....ie they had 4 before 0 and 4 advanced keyed into the crank gear but upon marking they were rotated so you thought they it was installed straight up but upon degreeing it showed 4 degrees retarded....etc....

How was the AF checked? not via accel ? or do you have a gen 7?

Did the other engines melt pistons? valves?
At 2000 it shouldn t take too long to pull it apart and SEE the damage.....

 

Joeseph,

I was unable to e-mail you. Is that your correct address? Could you try e-mailing me and I'll reply.

Thanks for the reply's everyone.

Re: Taylormade’s suggestion; I’m at 36 to 40* advance now under vacumme. Should I go higher? 46*-50*?

I have tuned with wideband O2 both hand held and printed on dyno chart. I have 72lb injectors flowmatched before recent build.

 

E-mail addy sent..

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Joseph Overton (accel/EMIC)
94 TA (new combo new year)
old setup:381,.020 over,5.7 rod,afr heads,comp cam,custom intake,1200 cfm tb,42# inj.,aeromotive pump,DFI,dry nos,th400,strange 12bolt,wolfe rollcage,subframes,lca,s
best n/a 10.95@124.06 1.55 60 ft.
best n20(.065 jet dry) 10.28@128.8 1.43 60ft.
bent torque arm on launch

 

have you ever fixed the problem?