Russ Murphy

What form does the stock DME/KLR overboost protection take when it intercedes? I was driving my stock 951 this cold morning and wanted to see the max boost where my LBE is currently set so I put my foot down in 4th and the boost climbed on the stock guage (I know, I know, but it seems to be pretty accurate, i.e. reflecting a pretty accurate barometric pressure and displaying 1.67 bar max boost before installing and playing with the LBE) tright between the 1.8 and the 2.0 mark and then the car balked as I was letting-up. I then gently got back on it and it cut out at about 1.4-1.5 bar. I got of the exit and at the end of the ramp when I stopped the car died. I held my breath and turned the key (visions of broken timing belts dancing in my head) and it started. I drove gently to work and parked it where it is now.

What gives?
Thanks,
Russ

Luke

mine never kicked in until about 2.3 (1.3 bar - 19 lbs). I never cranked it up that high. I had a punctured wastegate diaphragm.
Im pretty sure I can feel the ing. retard at about 16 lbs though. SO I never set it at any thing more than 15 lbs (stock chips)

Russ Murphy

Thanks Luke.
When it "kicks in" is it cutting fuel or ignition or what? At what boost level is it designed to "kick in".

Danno

I still think Luke has some special hot-rod 951 that he doesn't know about.

Anyway, the stock gauge can be accurate. Some of them are off because there's oil clogging the pressure line going to the KLR. Perhaps even contaminating the pressure-sensor itself. But I think a clear line should give accurate readings.

From what I've been able to gather, the overboost protection hits at 13psi on stock chips. Which is about 1.9 bar on the dash gauge. From the people who've experienced the overboost protection, it's not anything like hitting the rev-limit, it's more like hitting a brick wall with a fuel cut-off.

Perhaps you barely triggered it? I wouldn't turn up any more boost with the LBE until you get some aftermarket chips. At a minimum, you should install an S2 FPR to raise the fuel-pressure a bit so yo don't run lean.

rage2

I was thinking the same thing myself (again).

adrial

hey luke...How about you do some 60-100 times? That'll take the launch out of the equation and just show us pure power..

Method:
Start at 50mph, floor it...start clock at 60, stop at 100.

Just for comparison's sake...my 60-100 is 6.1-6.2 seconds. Only mods are listed below.

Luke

Some how I managed to knock off several teeth from my second gear (in stock form).
My intake valves look too clean to be original (I'm thinking head work was done).
woo hoo!

"A good freind of mine who is a mechanic has a 951 as well and he took mine out for a ride after I changed my engine mounts. He said "yep! She's deffinately chipped"
So the next day I went to check and the d@mn DME and KLR have never been touched."

Luke

just sold my k26/6 too. I wonder if it really was a 26/6?

Russ Murphy

Thanks Danno, Luke.
Fuel cut-off is exactly what it felt like and it was at 1.9-1.95 on the gauge. The second cut-out at 1.4 I guess was the self-protection mode I've heard discussed a few times on the boards.
I disconnected the battery and dialed the LBE down 1psi and the car was fine on the way home(1.85 on the guage).

Danno

Yeah, I think once you hit the overboost-proctection, it goes into some sort of low-boost limp-home mode. You have to turn off the car to reset it.

Luke, did you actually crack them open to take a look at the chips? It's actually pretty easy to open up the computer boxes and not make it look too obvious.

Luke

yes I did, but I could tell immediately because the pins on the cases had never been pried

and I still have the factory set rev limit