porshhhh951

a aftermarket boost controller doesnt have anything to do with the dme/klr. You can have a aftermarket boost controller on the car but, still be running stock chips and hit boost cut. I would think that would be pretty much common sense.

If you want to get rid of your boost cut, change into a set of chips that doesnt have one.

95ONE

So you're saying the stock engine management uses ignition to cut the boost, and not the stock cyclic valve right? (Which is what I expect, but damn, this thing is over 20years old. )

Anyone? I'm a facts guy. What is the fact?!! What EXACTLY does the stock computer use to cut boost when boost cut is engaged. ? Special Tool? John? Anyone? Thanks in Advance.

hally

the stock KLR chip is fine if you have bypassed the cycling valve.

Oddjob

The overboost protection is a fuel cutoff - which is a function of the DME, not the KLR. The DME is measuring the airflow through the AFM, and if the airflow is higher than a set limit for a period of time (1 second or so) through a given RPM range, it determines that the boost pressure is too high and cuts the fuel. You typically see the overboost protection kick-in in 4th and 5th gears right around or slightly above 5k rpms. If the car is really overboosting you can trigger it in 3rd, but will very seldom have it cutout in first or second (this is because of the time variable).

Most/all of the aftermarket chips remove this protection completely (or set it higher).

95ONE

Awesome. Thank you oddjob. This makes more sense than using the cyclic valve to cut boost. It would seem a common sense safety issue to use fuel or ignition rather than the cyclic valve in case of failure. I appreciate your tech info. SOOOOOOOOOOOOOOO.. everyone, what this should mean is, if you try to adjust the boost higher by any means on the stock WG or otherwise. You WILL hit boost cut. So, some sort of chip programming is necessary.

porshhhh951

Yes

As already stated above its the DME that controlls the ignition/fuel cut. I remember hitting mine so hard(I was playing with my LBE at the time) that the damn car would shut off. Literally I was be boosting hard through the gears and I would get about half way through 3rd and bam! It would just die.

Get yourself some vitesse chips and dont look back

toddk911

"Do you think there is another factor that may be bottle-necking power and preventing the 17psi from showing more gains?"

HEAT! at those higher levels the #6 and the 8 as well, are way out of eff. range and only produce more heat and that cancels out any gains in hp that the extra flow might have allowed.

I have seen dyno charts showing it is always better to flow LESS cooler air instead of MORE hotter air.

toddk911

"Nothing else was different between these two runs. STRICTLY wastegate. I was sure to keep that constant. Yes! 32 hp! "

So, with the dual port you kind of made the #6 into a #8 As that is about the same hp difference from base to turbo S.

95ONE

As proven by my most recent dyno chart thread showing 15psi vs 17psi. no discernable difference in the higher rpm. almost same hp. Turbo charger IS the bottleneck. (k26/6) There truly is no reason to do any other upgrade until a more efficient turbocharger is installed. Even though all those other things like Cam, intercooler, etc. the gains just aren't going to be realized (small) with that turbo. They're waiting, but won't show up until a better turbo is used.

RRRandy

At what psi does the stock chip cut the fuel? If its 15psi and you don't plan on running more than that, then what’s the difference? It would seem that having the safety over-boost protection would not be all bad. When you hit it, you know you are over-boosting, so you adjust the manual boost controller down a little. Surley, there is more to a set of chips than just the boost protection?

toddk911

From 15psi and beyond yes, but I was referencing 15psi and under.

Oddjob

The DME/KLR chips control the fuel and ignitions curves and the boost and knock control.

For a k26/6 car, the stock boost will peak around 11 psi in the mid range and drop off to 8 psi or so in the upper rpm range. So anything around 9psi or just slightly above, in the 5k-5500 rpm range, the fuel will cut out.

The stock chips will only allow you to run stock boost, otherwise the overboost protection will kick in. The fuel curves on the factory DME chip are mapped to match the factory stock boost curve. If you run more boost than stock, there will not be enough fuel supplied, and you will be running lean (bad). It will trigger the overboost protection/fuel cutoff, but it does not mean that you have not or will not damage the engine if you continue to drive the car with too much boost.

So, Do NOT run a manual/mechanical boost controller with the stock chips. If you want to run more boost, you need to get aftermarket chips(s) that have the fuel supply mapped for the boost you want to run.

RRRandy

Oddjob, Thank you. That is what I was wondering. The cut off is not an issue, it’s the manual boost controller and the fuel mapping. I am in the process of installing a DP WG, but was going to wait on the chips, as long it did not cause a problem. Sounds like it could. I think enough people have already told me “get the chips!”…OK, I will get chips…

Thanks guys!