V2Rocket

Anyone ever grenaded a motor running it too high?

James-man

That is a really good question. I have NEVER heard of a reasonably healthy stock 928 engine having any problem with standard chip-enhanced RPMs. The Authothority (most common) chipset takes the engine up to the max permissible RPM established by Porsche. Those that override the rev limiter to a much higher setting are more sophisticated with engine mods, and have nearly certainly done more extensive modifications, so that leads us to an entirely different "anyone grenaded an engine question".

The slightly higher revs can possibly magnify other issues such as oil starvation on tracked cars. I've seen the blame on any of these directed at chips.

With the mods I have, I have found that I start losing power (well, not really, but it levels and tapers off quickly) once in redline, so I tend to shift at or before. It takes a big WHOOPS to hit my rev limiter, but it still happens on these rare occasions.

Anyone have any NEGATIVE experience with chipsets aside from the common S4 comment relating to a wasting money?

PorKen

If the car has stock chips, and you hammer it at low rpms, the ignition pulls out 20° of advance, so it feels like there's a hole there. Chips (or my tweak) remove this sensation.

On the dyno, my '86.5 (chips, X) kept making pretty much peak power from 5500 until redline. My '81 peaked about 5500, too, but then drops sharply.

The 2.75 rear end ratio makes the 16V seem peppy at the low end. Properly tuned, the 32V will be just as quick with the 2.20, and it keeps going, and going... With only chips and an X, the early 32V will easily make the factory quoted crank HP...at the rear wheels (>330HP crank)!

The sound of the 32V engine at high rpm is a thing of beauty.

James-man

So your tweak is comparable to chipset? I am interested. My chips only lowered the dead zone by a couple of hundred RPM. I still get that turbo-like kick. If your tweak corrects for this entirely, it may be superior to chips. Has anyone tested stock + chips, your tweak, and your tweak + chips? Add Xover pipe to the above Q. Thanks!

PorKen

I don't think the (EZ-F tweak) has the same maximum advance as the chips, but it does take away the dead zone. I only have driven my automatic, so the torque converter may be masking some of the feeling. Have you checked your cam timing?

The tweak + chips makes for pinging (you can advance the idle, though). My clone chips gave ~10RW HP+TQ over stock chips. If I get a chance, I want to try dynoing the tweak, but I don't think it will change the maximum HP over stock.

The MAP sensor also retards 20° with low vacuum/WOT. Hmmm...I wonder what would happen if I put a small vacuum reservoir before the EZ-F...

I would like to also try retarding the cam timing a few degrees. I think that might push the HP over the magic 300RWHP.

James-man

My car dynod with RMB + chips @ 272 peak (at the wheels). I like my mid to upper power. I accept my abrupt low-end transition as a fact of life. I haven't checked my cam timing.

I dynoed last year with RMB + Chips + Xover, but due to dual exhaust leak and vacuum leak, I only pulled in the mid-high 260's. My cams might already be set a little hot? The original owner only put 17k miles on this car and I am pretty sure that he didn't have anyone mess around with them, so I don't know how or why mine might be set more aggresively.

Keep us posted if anyone with a manaul has good results with your EZ-F. I was assuming that variable cam timing upgrade was the only reasonable resolution for low end performance while maximizing the upper end. Maybe that assumtion still stands, maybe not?

PorKen

Are you sure those are hot chips? (The EZ-F chip gives the most benefit.) I got high 270's with the factory chips + X + '86.5 big resonators + RMB + PCVB. Could be dyno differences, I suppose, or maybe it's the real Ott-)(-pipe.

Check that your air temp sensor (airbox) is connected and/or giving the proper resistance. If the air temp sensor is broken or disconnected, it's the same as plugging in the octane loop (check that too), 3° retard at high load/rpm.

It's possible, but unlikely with that mileage, that your cams are not syncronized.

James-man

I kinda feel that we hijacked the thread a bit.

I got 272 with my stock cats in so the chips gotta be hot, unless someone swapped them back to stock while I wasn't looking (a stock 86.5 dynoed 250 the same day and an 85 dynoed 235). When the Xover was added, I've found that it is just too darn easy to develop exhaust leaks. When the exhaust is hot, Resonators + RMB work their way fore and aft during heavy braking, loosening things up enough for the fiberglass wrap (or alternative insulation material used where resonators mate with the X) to get blown out. I don't want to weld or "glue" because I want to rotate between stock cats and performance exhaust. At any rate, the point is, I can fix an exhaust leak on Friday. Drive hard on Sat & Sunday, and come monday, notice that the exhaust sounds funny again (exhaust leak). My mechanic found the intake leak, but exhaust leaks are CHRONIC.

Now as far as power goes, I am not sure how much intake and exhaust leaks rob power, but even on a good day when everything is tight, I don't think that 20+ chip hp gain and 25+ X gains are really cumulative. I haven't heard any 86.5 dyno results of chips versus chips + X. I may be down on something else at the moment, I have 1100 idle speed (just changed oxy sensor last year, so it shouldn't be bad). Air temp sensor is probably about where my lack of engine knowledge begins. I wouldn't recognize it if it bit me on the nose. Is it really in the air box or underneath? How to check? Thanks!


BACK TO REGULARY SCHEDULED TOPIC OF 16v vs 32V

16V sound vroomy. 32V act vroomy.

PorKen

16V = scurry, 32V = stride.

Your high idle may mean the idle switch is not working (you can check with a timing light, ~10° at idle if working, ~20° if not), and if it isn't, the full load/WOT switch may be disconnected to.

LaughaC

My 32 valve '87 S4 felt like it had a powerband that kicked in from around 3500-5800 RPMs when I mashed the button under the accelerator.

The powerband was not as distinct as the new variocam motors I've driven, and I had to wonder if the tall gears were causing some low-RPM sogginess. The new variocam motors remind me of 2-stroke dirt bike powerbands that can throw your head back in lower gears.