Vandit

I recently installed an 93 octane FVD chip I bought off a friend who went w/ a 91 octane SW chip (also a RLer, Regulatori). Previously, I had the stock chip. I was driving the car hard today and I think I noticed now the rev limiter won't kick in till about 7100. Is this operating rev range safe?

I plan on autocrossing the car regularly over the summer, and anyone who has autocrossed can tell you there's plenty of times where riding the limiter is better than shifting to the next gear, so could this raised limiter potentially create a longevity compromising situation?

Thanks.

PehrJ

No, do not rev more than 6800.

Geoffrey

It has been my experience that the valve spring pressure matches the factory, stock rev limit. Increasing the rev limit won't allow the valve to operate properly and I've seen a number of engines where the retainer and/or spring has broken from spring coil bind when overstressed. Keep the rev limit 6800.

Steve Weiner-Rennsport Systems

Totally concur.

Those OEM sintered-metal valve spring retainers are somewhat fragile when operated at high RPM.

You need a chip that retains the stock rev limiter unless you upgrade the springs, retainers, and rod bolts.

Vandit

Just as a follow-up question, I was discussing this w/ my friend who I bought the chip from and he clearly remembers his rev limiter kicking in at the appropriate 6800 when he had the chip installed. Is there any reason why it would be higher when installed on my car?

His car is a '93 C2, mine is a '91 C2.

Makmov

No!

besides the aforementioned valve train/spring weakness it's at a good RPM for a stock rod bolt failure.

Vandit

I'm not asking to justify spinning the engine that high, i'm asking to figure out why it's behaving like that to see if it could possibly be something else. Like I said, same chip, two cars, two different rev limiters. Doesn't make sense.

Anyone else on here w/ an FVD chip that can give some feedback?

sml

i thought that was what you were asking.
has the question has changed?

Vandit

Yes, the question has changed. Is that okay with you all? Would you prefer I create another thread to address this slight variation of question?

I think it was abundantly clear that 7100 is not a safe operating range after the first few responses, therefore, now, i'm asking why it would behave this way if it performed differently (stock limiter) when it was installed on the prior owner's car. Same chip.

BHMav8r

> 6800 asking for trouble $$$

Look at the Hp curve . . . youre not getting any more power there anyway. Is this a track application?

Also, I dont know for shure w/o looking it up; but aftermarket chips may not have revlimiting . . . see first sentance.

My car has a chip (came with it), but I dont take it over 6000 rpm, typically.

Marc Shaw

The software does not change if you move the chip to a new car.

Marc

Ken D

Assuming your friend's memory is correct, then the difference is not due to the chip. I am guessing there may be an issue with your speed sensor, which is positioned over the flywheel and determines engine speed.

There is a procedure in the factory manuals to check the electrical output of the sensor, as well as how to ensure it is clearanced properly.

This also assumes that your FVD chip does not raise the rev limiter. You should call FVD USA to confirm this before doing anything else.

Lorenfb

"Assuming your friend's memory is correct"

Big assumption!

"then the difference is not due to the chip."

Correct! Most likely the result is different tach calibrations which can vary +/- 3%.
Assuming the actual limit point was 6900, then your tach may be reading ~ 3.0%
on the high side and his may be reading ~ 1.5% on the low side. So that would
indicate that each tach is within +/- 3% which is also within the tolerance one might
expect from a non-precision instrument as a tach.

Bottom line: If you're really concerned, then pull the tach and have it calibrated for an accurate
reading at 6800, as tachs are accurate only at certain RPMs, i.e. the accuracy varies over the range.