JLeake

I was reading an old post by Danno (see below) about shimming wastegates when I realized I may not need new chips after all to increase my boost level. Can I just get a 3 bar fuel pressure regulator and increase the spring tension on my check valve type boost enhancer to say 14.5-15 psi? My cyclic valve has been bypassed. Will the pressure regulator ensure a rich enough mixture under WOT and full boost? Am I going to be limited to say 13.5 psi or whatever boost level my particular car goes into overboost protection at? I think this is the case, but am looking for some confirmation. (What exactly does overboost protection do? Retards the timing, right? Anything else?) I attempted to shim my wastegate, but after breaking a stud I'd rather just use the boost enhancer to increase boost for now. I understand that shimming is better at holding boost under high RPM conditions, but I can always shim it later (I've got the washers ready). I'm saving my money up for a helmet and DE events...it's hard enough to justify these expenditures to the wife, let alone a set of chips. TIA This forum rocks.

And Danno, if you read this did you mean your original mod provided more power than the APE chips, or that the increase from stock to your mod was greater than from your mod to APE chips? Thanks!

And now Danno's post I was referring to:

"Piece of cake! Shimming the wastegate will typically add about 2psi to your boost (about 18%), bringing it up from 11psi to just under the 13.5psi where the stock overboost-protection kicks in. But I've heard of A LOT of people not getting fuel-cutoff even at 15-17psi.

The extra boost will not cause you air-fuel ratio problems if you're not at full-throttle/high-RPM since the computer will still use O2-sensor feedback to adjust injector duty-cycle to match the air flow.

When it does go into open-loop mode, it uses a fixed duty-cycle to RPM look-up table. To make ensure correct air-fuel ratio in open-loop mode, increase the fuel-pressure. Get a 3-bar fuel-pressure regulator from Jason @ Paragon ($38). This coincidentally is 20% higher pressure than stock, roughly matching the 18% higher boost you'll have from shimming the wastegate.

I would initially shim the wastegate by just 2mm and watch the boost-gauge carefully. You want to shim it just enough to bring max-boost from 1.7 to 1.9bar. Do several runs with increasing throttle, watch the boost gauge and listen for knock.

Increase the shim-stack until you get 1.9bar on the gauge. About to 3-4mm, no more than 5mm due to coil-bind in the wastegate spring. If you get some pinging, you can retard the ignition by 3 degrees using the fuel-quality switch in the DME.

This was actually the first engine-mod I did on my car before I got a manual boost-controller and APE chips for full 15-17psi of boost. Which didn't give me as much of a performance boost as the simple wastegate-shim/3-bar FPR mod I initially did. I attribute this to the excessive amounts of ignition retard dialed into the APE Stg.2 chips and excessive mid-range richness. My guess is that APE did this to cover their a** and also to allow people to run 20psi of boost. "

adrial

The overboost protection will still hit with stock chips even with the cycling valve bypassed...
It's either cuts fuel or spark... (duh)...I think spark but not sure)

If you want cheap chips look at ebay...

KW951

None of the chipsets out there increase boost by themselves. They all do it by using a replacement banjo bolt or shimming the wastegate, and work equally well with a boost enhancer or manual boost controller. The importance of the chips is in providing a correct level of fuel enrichment to match you increased boost, as well as turning off the overboost protection. If you shim the wastegate without swapping to a stage II chipset your car is gonna boost to 12psi and then feel like it hit a brick wall when the KLR fuel cuts on you. You then have to turn the car off and back on before the DME and KLR will go back to normal mode. If you want to increase boost, there's really no reason to not get a set of chips - they aren't very expensive, especially if you find a used set.

adrial

SFR's (http://www.speedforceracing.com) chips increase boost. Just chips, nothing else, no restrictors/MBC.

The KLR controls the cycling valve...so it makes sense.

BTW my car stock was running 12psi, so I expect the brick wall is higher than that? (ok, ok...it was 11.9 says the dyno)

toddk911

I was just reading tha old post of Danno's last night as well.

I was trying to find out what the difference is between runing the LBE or shimming the wastegate.

Also, I can confirm, from what I have been told by many gurus in here, that MOST chips do not touch boost. They merely increase fuel to allow you to run more boost.

Can anyone offer their opinon of the most cost effective air/fuel controler?

Danno

Just to clarify that previous post, bumping up my stock boost from 11psi to 13psi (with stock chips, shims and FPR) gave me a more noticable improvement than going from that 13psi point to 15psi with AutoThority Stg2 chips. BUT, I was hitting overboost protection at 13.5psi or so with stock chips whenever I managed to spike the boost up that high. Like a super-fast shift in higher gears. However, 15psi with Stg2 chips was still faster than my previous halfway mod.

"Also, I can confirm, from what I have been told by many gurus in here, that MOST chips do not touch boost. They merely increase fuel to allow you to run more boost."

Yes, that's true. The chips ONLY allow additional fuel to meet the demands of increased airflow from increased boost. Without the additional airflow, the extra fuel from aftermarket chips would just drown the engine and you'll get less power. That is, if you install aftermarket chips and keep the stock 11psi of boost, you'll have a slower car.

A lot of folks have tried to increase boost using KLR programming only with mixed results. That's because the KLR doesn't use feedback control to monitor boost levels set by the cycling-valve. It just runs a pre-programmed duty-cycle curve. Increasing this curve will increase boost to a certain extent. However, the limit will be the strength of your stock wastegate spring. The same re-programmed KLR chip can provide mixed results of 12psi, 13psi or 15psi boost depending upon the car you're installing it into. That's why the original AutoThority Stg.2 kits came with three different sized jets that you install into their threaded banjo bolt. One of them will yield the desired 15psi of boost.

That said, you want to use shimmed wastegate over a banjo bolt. That's because the shimmed spring will increase boost across the entire RPM band, whereas the banjo-bolt mod only provides a momentary restriction of pressure going to the wastegate. But that pressure will ultimately build up to the same level and open the wastegate, just several seconds later that's all. So in effect, you've created an intentional boost-spike.

toddk911

Danno, I was reading another older post of yours about air/fuel ratio and you said doing some dyno runs and nailing that 12.5-1 ratio (or is it 12-1??) got you an increase of 70hp at the wheels!!!

That says alot about the importance of the air/fuel ratio and that it serves very little importance to do heavy mods wih out having that a/f nailed down. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />