2002 ETC
Comp
B1-2
Comp
Mach4s
AFE
4" straight
Denver 5000' +

Want to ask some questions regarding the relationship between boost and EGTs

Just picked up some 4s from Don and results are a little different than I expected.

I started bombing with just a Comp and noticed right off the EGTs were up a lot. On 3x5 I could hit 1400 pretty easy. With boost elbow I could pull 28-30psi. Then went to a set of Mach2s and EGTs went even higher. Could hit 1500 on a decent 5th gear pull. 5x5 would hit 1650 in short order. Boost stayed close to the same maybe up a couple points to 30-32 psi

Installed B1-2 and EGT drop was dramatic. on 3x5 EGTs were hard pressed to go over 1100 maybe 1150 on a long pull. Boost went up to maybe 34-35. On 5x5 I could get EGTs up to maybe 1250-1300 and boost around 36. At this point I thought boost seemed low but with EGTs in check it did not seem as though I had a leak.

Just installed the Mach4s and was expecting EGTs to get up in the 1400 range on 3x5 and boost to be up close to 40 or more. Nope! While truck seems to have a more touchy go peddle with the 4s and be more responsive, the EGTs and boost are almost unchanged. I could make it hit 1190 on 3x5 but boost was unchanged maybe even lower. Keep in mind I am running my small 32" studs and not my 35" tires I run in the summer but I figured EGTs would be up and boost at least 40 psi? With 4.10s it's hard to put a hard pull on it. You romp it at 45mph and in a matter of a few seconds I am topped out at 80mph. I just can't see that I have a boost leak when EGTs are so low. I really thought with Mach4s, Comp, and B1-2, I would see boost on the 40-45 psi and EGTs up around 1400(3x5) I figured I could run water/meth for 5x5 dyno runs or smoking those silly Fodes but at this point I'm starting to wonder if water will be needed.

Anyone have any ideas how one could run Mach4s at 5000' with a Comp and EGTs and boost are laughably low? Don't get me wrong... the truck runs hard and smoke is low if you keep your mind. I'll wait until I get my 35" tired back on and can put a 5th gear pull type good load on it, but at this point I'm wondering if some 5s or 6s are around the corner. I want to fuel until I see EGTs around 14-1450 on 3x5 and 1600+ on 5x5 at which point I can cool it with water. I only hit 5x5 on rare occasions so don't care if I have to water it down on those occasions. Thanks!

BTW Don is a great guy to deal with. Can't recommend his stuff enough.

 

I can tell you how your EGT's are laughably low. There is no O2 up here. I'm in ABQ and see the same thing. I'm between 5k and 6k depending where I'm at in the city and my truck just doesnt get hot like the guys at lower altitudes. granted a diesel runs kinda backwards compared to a gasser, but for a given volume of air produced by your turbo at 5k feet vs that same volume of air at sea level. There will be considerably more 02 at sea level hence the greater sensitivity to heat produced by extra fuel at lower elevations. Up here we don't need to worry quite as much.

Just keep in mind that the less 02 the colder the flame. In 2 reactions with the same fuel it is that amount of oxidizer (in this case 02) that will determine the heat of a reaction. Let us know how those Mach 4's treat you! Scott