LST2

So I finally got my EGT to work. Problem is my EGTs start to rise pretty high past 6 psi. Here is the setup:

-85mm LS/VTEC w/ 9:1 cr
-Darton Mid sleeves, Eagle Rods, CP pistons
-T3/T67
-3" straight exhaust
-Uberdata
-Equal length mani

I am running about 1,100*F in cruise and about 800*F at idle. I go up to almost 1,700*F by 6psi and 1,800*F by 10psi. I lowered my AF to about 11:1 at 10psi. My timing is already pretty advanced with 22* by 13psi. Maybe with larger bore, lower cr and larger turbo the engine wants more timing. I hate to bring up the timing much more but I don't think I want to add anymore fuel.

BTW, I am using a Techedge logger to measure the EGTs and it datalogs at 10 frames/sec. I used a mechanical gauge to calibrate it correctly while idling and cruising for a few minutes. The actual mechanical gauge never reads higher than 1,500*F b/c I think it "averages" the readings a bit and takes a while to catch up to the actual readings at any point in time.

Any thoughts?



Modified by LST2 at 7:08 AM 9/23/2005

elpiar

have you tried retarding the timing? usually advancing it raises EGT

JDogg

have you checked the cam timing, have you made sure the ign timing is synced properly?

LST2

I think retarding increases EGTs. Advancing timing should lower EGTs unless you advance it to the point of detonation. I have not heard any detonation (I boosted up to 1bar before I put in the EGTs) and the plugs look good.

The cam timing is right on. I checked the distributor timing twice and I notched the adjustment bolt on the dist to make sure it did not slip.

22* at 13psi is already pretty high huh? I heard H22s can get higher b/c of the larger bore so maybe the 85mm bore has something to do with it.

Boostage

water injection.

LST2

That is my next setp. I actually have the pump and tank and lines sitting in my trunk waiting to be installed. I just wanted to get a good tune first. I was not expecting my EGTs to be so high to start off with... Maybe everyones EGTs are just this high if you datalog with high resolution rather than the averages on the EGT mechanichal gauges.

Joseph Davis

Idle sounds right, but cruise w/ correctly functioning closed loop should be 1350 deg F. That's the first clue that something might not be kosher on the mechanical level - JDogg got it right (yay!!11) check your base and mechanical timing.

I doubt the analog ("mechanical") gauge reacts as slowly as the K-type thermocouple itself. Most of the stainless bullet protected junctions react very slowly to temperature changes. I've had problems with TE units and ground loops, before I'd lend too much credence to the TE claimed EGT I'd borrow or buy (and return when done) a DVOM with K-type thermocouple reading capability. By 1700 deg F combustion temps, you have dissassociated the water formed by combustion into component hydrogen and oxygen. At 1700+ deg F they do not seek out each other to form water anymore, they seek out Al and Fe in your engine = hot, tasty engine death.

Now, the 1700 deg F readings may be correct, but solely on the exhaust side of things. Afterburn in the manifold from overly rich mixture, aforementioned cam or ignition timing. I typed the last passage to illustrate why I do not think you have 1700 deg combustion temps.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostage &raquo;</TD></TR><TR><TD CLASS="quote">water injection.</TD></TR></TABLE>

Does not neccesarily lower EGTs.

LST2

Thanks, I am positive my cam and distributor timing are good.

I have advanced the timing from stock quite a bit around curise so maybe that has lowered my temp. When I say cruise I mean city cruise... 2,400 RPM in 5th. On the highway @ 3,600 RPM I get closer to 1,300-1,400.

It is probably something to do with the TE unit like you said. I am going to try to hold it in a long 3rd gear pull and see what the mechanichal gauge reads.

But I guess the consensus is not to raise my timing anymore than the 22* I already have it at.

I am going to put in on the dyno at some point but I am trying to get the tune close before I go.

mike1114

iTrader: (1)

get a better tuner...that'll lower egt's!!