CyCloNe!

Hey guys I finally got enough leg room to get my car boosting in 4th gear but for some reason it doesn't seem to have as much punch as third does. 15psi is gained at around 4k RPM and it builds slow. No vac leaks my hg is at 17-18 on idle and builds quick in the other gears. Only thing I can figure is maybe leak at the crossover pipe, too much blow by, or I wonder if a wastegate or mostly clogged cat would contribute? Any ideas, thanks for your time gentlemen.

lart951

what kind of wastegate do you have?

toddk911

What kind of turbo? 15psi in 4th is boost leaks unless you have a #10 hotside or some crazy big old turbo.

Tom M'Guinn

Do you have a zeitronix (or other) log to post? At what rpm do you reach 15psi in the lower gears?

refresh951

You need a tial wg. With your other mods this is a must. Also, the cat is a significant restriction. These two changes will make a very noticeable difference.

lart951

here Conrad, check the link

https://rennlist.com/forums/944-turb...ml#post2666718

Lethal951

It might be because you are running richer A/F ratios due to the higher load in 4th... If your running richer in 4th gear it will cause the car to feel weak during the pull in 4th.... Its cause the load is higher then in 3rd gear.

Reimu

I spool slow too on my 60-1. I've gone over crossover/vacuum leaks like crazy and I don't have a cat. 38mm dual port and everything yet I hit positive pressure at 2900rpm or so and don't see 15psi till 4k or maybe a little after it. Guess I'll just sell this turbo to a racer who doesn't care about lag and buy something with an acceptable spool (at least 3500 to 1 bar).

Lethal951

I hit full boost around 4200... but I have a super 75 @ 20psi.

CyCloNe!

my wastegate is basically stock, it was a modified one by a rennlist member to open earlier and hold pressure to 15psi. I'm going to check for leaks and look at my plugs to see any signs of richness or oil and then proceed to cat delete and a tail wastegate.

Lethal951

Yea, check plugs and do yourself a favor a cut that 25 year old Cat off the car man... THat thing was the reason why I had to rebuild my k26 twice due to back pressure.