When I give it any sort of part throttle my egts skyrocket immediatelly. Full throttle EGT is fine, but part throttle they skyrocket and will easily cross 1600 almost immediatelly (TRE probe). My AFR seems fine(14.7), fuel trims are fine. I've driven it like this for awhile and haven't melted anything, but it is starting to urk me and I think whatever the problem is could also be contributing to my slow 1/4 times; 14.4@99 @ 14psi. What in the world would cause my egts to sky rocket so fast part throttle? This is not just part throttle boost, but also in high vac(near 0psi) and rises much quicker under part throttle boost. Any suggestions?

If you're A/F is at 14.7...you are VERY VERY lean. Richen that badboy up man!

yea, definately too lean. 14.7 is stoich, but only to be used for n/a applications. I'd say shoot for 12.0-12.5

Originally posted by WIDECLIPSE
yea, definately too lean. 14.7 is stoich, but only to be used for n/a applications. I'd say shoot for 12.0-12.5

but if he's at part throttle no boost wouldnt 14.7 be right ?

Originally posted by boosted60trimrst

Originally posted by WIDECLIPSE yea, definately too lean. 14.7 is stoich, but only to be used for n/a applications. I'd say shoot for 12.0-12.5

but if he's at part throttle no boost wouldnt 14.7 be right ?

This is pretty much the bad part about turbocharging NA engines. The factory ECU is setup to operate in closed loop during cruise and part throttle. When it's in closed loop, the ECU is looking at the o2 signal + other sensors and making adjustments to get the air/fuel ratio back to 14.7:1 and optimum ignition timing, which is a bit leaner and advanced than you want to be even at cruise/part throttle with a turbocharged engine.

The only way around it is to change your fuel & ignition systems, max out your fuel trims, or lift off the accelerator (which sucks because then you're accelerating very slowly). The factory ECU is pretty much going to lean it out to 14.7:1 no matter what you do.

Is 14.7:1 at part throttle my problem? They go close too and over 1600º in low vac also. My friend with a WRX says his egt's are around 1300 under part throttle boost around the same AFR.

Well another aspect to consider is "lower compression = higher egts in general, higher compression = lower egts" A diesel has cruising egt of 900F.

With our built motors you should be cruising around 3k rpm in fifth gear and be around 1400-1450. Higher MPH and the EGt was even higher. With stock Fuel thats where i was.

I recommend considering a MS or other form of fuel management to remedy the issue.

Terry

What is your fuel system setup Sike? Are you just running 40# with a SFMU? Where do you have your probe tapped at on your mani? I mean my motor isn't build yet and my EGT's don't get above 13 during closed loop and 15.3ish at WOT. My probe is tapped in right were all 4 tubes come together on my mani. I know some say tap it outside of #4, but the mani was already tapped there by phenominal when I bought if from him.

42# with SFMU. It's taped in the same places as yours, where all 3 runners collect. I dunno why my EGT's are so high, I'm pretty sure it is not fuel related. I think it has something to do with ignition timing, I'm going to try a new CAS.