mroberts

I've been doing some thinking (a dangerous pastime), and I was wondering about using a needle valve as a boost controller.

I'm certainly open to comments or corrections.

I have the APE Stage II chipset and a shimmed wastegate. AFAIK, the APE chips are designed to be run with a jetted banjo bolt as a method of boost control / enhancement.

The chips are mapped based on this, assumign that there will be some drop off in boost at high RPM. There is a belief that using a standard MBC is bad because it holds boost constant at high revs, rather than dropping off.

The jet in the banjo bolt seems to act as a restrictor to slow the rate of increase of pressure, and by adjusting the orifice, you can set your boost.

The kit was already installed in my car, but I understand they supply multiple jets so you can tailor it for your particular car / WG.

A needle valve is really just an adjustable orifice, so my thinking is by replacing the jet wwith a needle valve, you actually have a continuously variable orifice that should allow for more precise tunign while still keeping with the same "concept" and overall behaviuour that the chips are deisgned for.

HAs anyone tried this ?

eniac

Holding constant boost is the main reason WHY people remove the CV and go to a MBC/EBC and dual port WG.

mroberts

Yes, but apparently the APE chips aren't mapped for it, and that's why people have issues with them running a bit lean at high RPM's.

Please don't suggest that I get new chips.

x15jq

Hey I have been running a needle valve on my 86 turbo since last march. I got ape stage 2 chips and the guy never gave me the banjo insert so i had no choise since ape didnt want to sell me the jets seperately. It works perfectly, i just turned it up till it was a hair before 2 on the stock gauge and in the 1 year ive had it like this no problems no over boost nothing. I retained the cv tho.

mroberts

That's cool ! Where did you get the valve from ?

I'm planning to keep the CV too.