oaborbag

So I FINALLY got the guts to hammer down with my drag comp on 5x5 after the o-ring install, and I forgot how laggy this thing was. All in all it felt good but....

I have noticed a difference than it used to feel. Prior to o-rings I could hit about 53 psi and it would it hit just over 2k rpm, now it only hits 45 psi until about 2300 rpm then climbs up to 50 psi until redline, pulling harder until I let off, never got that close to red line, probably 2800 rpm max. What could be causing the difference?

During the o-ring install I also changed my mainfold to a HTT 3 piece, so that should have helped the spool I'd think. Whats the deal on this? Not a big deal since the truck runs, just wondering why the spool is slower and lower boost.

Egt's hit 1500 and stopped there until I let off btw, so it clears the mach 6's fairly decent I'd say, I'd like to see 100+ degrees lower, but I know thats asking a lot with a single charger.

Mike D

Did you go back with a stock gasket?

oaborbag

Yes its a stock gasket.

oaborbag

The head is also a reman from Puredieselpower with the o-rings installed, so I don't believe I would have gained any comp ratio, if anything maybe I lost some with the o-rings? Just what I'm gathering after doing some quick research last night, anyone know why it'd be different after the head install?

kawi600

thats weird.. you sure you didnt go oversize on the gasket?
Otherwise Id inspect the intake system for leaks

oaborbag

I got a stock cummins head gasket kit, so I'd suspect that it's just a normal gasket since I didn't specify oversized. I might check around the intake plenum see if I see any leaks. I also changed boost lines after the install, because I kinked the old one really bad trying to twist it off the head.

oaborbag

Took for another drive, maxed out at 50psi again, fuel pressure dropped to around 12 psi or so, and egt's climbed kind of high. Starting to think this turbo can't cool the big sticks, but maybe I need more boost. Should I just try adjusting the wastegate? Maybe it was bent a bit on the reinstall. But I'm not sure if tightening it would make more boost or less....I'm stumped on why it's a bit lower though unless for some reason I do have a lower comp ratio now.

It's been in the back of my mind after doing some research, but compared to the turbo I have now, how would my stock hx35y with a new compressor housing like the one many people do over a larger turbo such as s400 or something like that? Would I gain power or lose? I'm sure my egt's would drop and spool would be much better, this thing is laggy! I'm just throwing that idea out there before I try adjusting the wastegate on my super b special.

Mike D

I was seeing pretty much the same thing when I had M6 and ran the BD special. 1500-1600 depending on the weather.

Do you have a adjustable boost elbow?

oaborbag

I have whatever the turbo came with, I never changed it.

JFlory

Get a mirror and check all around where the turbo bolts up to the manifold. It sounds like you might be loosing a little drive pressure. Also look around the manifold where it bolts to the head for soot.

You would be shocked how much a small exhaust leak will hurt spool up.

J.D.

oaborbag

I "hope" I found the issue, the front bottom nut that holds the turbo on wasn't even finger tight. I need to get a shorter 15mm wrench to tighten it, but hopefully that fixes the issue of lag + lower boost. Thanks for the replies.