Compression Test Results

Reply Subscribe

Thread Tools

Search this Thread

May 31, 2021 | 10:41 PM

genscripter

Thread Starter

Cargo Master

Joined: Oct 2012

Posts: 3,072

Likes: 48

From: California

Compression Test Results

I finally had an afternoon to devote to doing a warm-engine compression test. I decided to avoid #4 from the start, because in a van, and with the hypermax kit, I'd have to remove the injector lines, GP harness platform, and a bunch of other stuff to get it, and the other 7 weren't going to be a breeze either.

So I got 420-460 psi on all 7. That's pretty decent. I have over 25,000 on this rebuild from 2018, and I purposely gapped the rings to be just at the minimum of spec.

I'm pleased with the results, but the main reason why I did this was to diagnose my slight smoke at idle, and my high EGT's up long grades. I thought maybe bad compression would explain both, but clearly that's not the case. I know the timing is fine because I set my timing myself.

I think the main reason why my EGT's are high up California grades is because I don't have an intercooler. My intake probably keeps taking on heat and there is no downhill to let it cool off. The hard part is there no space in the van to get that down without major modifications. Maybe a cold air intake would help as well.

Jun 1, 2021 | 10:57 AM

RaymondIV

Elder User

Joined: May 2018

Posts: 695

Likes: 22

Quote:

Maybe a cold air intake would help as well.

I doubt it. I have the original cold intake on my ATS turboed F-250 and like driving a semi, aftercooler or not, the only thing that drops EGT's is grab a lower gear or two. Pulling long grades with a heavy load, the higher the RPM's the lower the EGT.