? for alky users

[JDSfastGN]

Somebody correct me if I'm wrong in my assumption. My last time to the track about 4 monthes ago resulted in both headgaskets blown. Turns out my pump stator in the tranny had come loose and tore up the splines in the TC and I lost a lot of line pressure and the tranny became really inefficient. Anyways past the 1/8 mile marker it all happened quickly and the tranny couldn't hold 3rd any more and slipped horribly hitting the rev limiter. I instantly blew both HGs. I know the rev limiters cut fuel which is not the same as a lean condition as there will be no fuel to burn in the cylinder but with alky being sprayed in there does this not make it a lean condition for a split second? Has anybody else encountered anything like that? Or is my thinking off here? I'm thinking about taking my rev limitor off to avoid stupid problems like leaving it in low 2 and forgetting to shift into 3rd etc... Just curious. On a positive note the car went 95.8 on that pass in the 1/8 and still coasted to an 11.87 at 104 on my 17" wheels and tires(crap 60 ft), thats more mph than it had on my best run on race gas

 

[Razor]

Pull the limiter out of the chip. Or set it to 6400

My very first HG went from a flare on the 2-3 shift at 29-30 PSI. It bounced off the limiter and cut fuel. At the time I was also running a lot leaner.

So you get a car run it at 1650 EGT.. bounce it off the limiter creating a leaner condition at high boost.. guess what happens.

I tune my car at 1500-1520 now.. it increases my safety window dramatically. And confirmed with a WB its 11.7-11.9:1 AFR. Picks up 25-27 1/8-1/4.. And got rid of the limiter function on all my chips. No more HG issues.

Tranny's can cuase issues..

 

[JDSfastGN]

Originally posted by Razor
Pull the limiter out of the chip. Or set it to 6400

My very first HG went from a flare on the 2-3 shift at 29-30 PSI. It bounced off the limiter and cut fuel. At the time I was also running a lot leaner.

So you get a car run it at 1650 EGT.. bounce it off the limiter creating a leaner condition at high boost.. guess what happens.

I tune my car at 1500-1520 now.. it increases my safety window dramatically. And confirmed with a WB its 11.7-11.9:1 AFR. Picks up 25-27 1/8-1/4.. And got rid of the limiter function on all my chips. No more HG issues.

Tranny's can cuase issues..

Thanks Razor thats what i was figuring I should do, ive always had a bad habit of dropping it into low 2 and forgetting about it. Always seems to happen on my best runs

 

[Hyboost4Banger]

The rev-limiter-alky issue has hurt us DSM guys too. We use the clutch switch to activate fuel cut at a pre-set RPM to WOT shift our 5 speeds. Our little engines are naturally rev-happy. Normally it's fun to bounce off the rev-limiter. Not no more. I got lucky. Delamananted the stock HG and bent #3 rod. Two of my buddy's with upgraded HG's have not faired so well. Both pitched rods. OW! I haven't figured out how to stay off or deactivate my rev limiter yet. I'm putting the pieces back together now. Can't say I have a stock un-opened block anymore.
Mark

 

[JDSfastGN]

Originally posted by Hyboost4Banger
The rev-limiter-alky issue has hurt us DSM guys too. We use the clutch switch to activate fuel cut at a pre-set RPM to WOT shift our 5 speeds. Our little engines are naturally rev-happy. Normally it's fun to bounce off the rev-limiter. Not no more. I got lucky. Delamananted the stock HG and bent #3 rod. Two of my buddy's with upgraded HG's have not faired so well. Both pitched rods. OW! I haven't figured out how to stay off or deactivate my rev limiter yet. I'm putting the pieces back together now. Can't say I have a stock un-opened block anymore.
Mark

Sorry to hear that man, i hadn't read much about this but figured I couldn't have been the only one that has had it happen. Sorry to hear about your motor man, mine has been rebuilt but I was still proud that after having this car for 5 years now I still had yet to blow a headgasket but that wasn't meant to be. Good luck getting it back together, sounds like a badass little DSM

 

[Razor]

Originally posted by Hyboost4Banger
The rev-limiter-alky issue has hurt us DSM guys too. We use the clutch switch to activate fuel cut at a pre-set RPM to WOT shift our 5 speeds. Our little engines are naturally rev-happy. Normally it's fun to bounce off the rev-limiter. Not no more. I got lucky. Delamananted the stock HG and bent #3 rod. Two of my buddy's with upgraded HG's have not faired so well. Both pitched rods. OW! I haven't figured out how to stay off or deactivate my rev limiter yet. I'm putting the pieces back together now. Can't say I have a stock un-opened block anymore.
Mark

I was talking to Jerry locally.. lancernman on the DSM forums and he hasnt had this problem. His car is a mid 10 sec DSM(maybe 9's in the next few months). It may be if the outside temps are really cold where the issue may arise. The cars in question were up north.. and not subject to the 90-100 degree temps we have here.

Lucas was saying his thoughts were pre-ignition when bouncing off the rev-limiter between shifts.

In any case having an external fuel source(alky) and at WOT bouncing off a limiter that cuts fuel off.. changes the mixtures big time. And the imports seem to run WOT and bounce of the limiter to stay spooled up. This symptom only has happened on multiple nozzle apps running really large volumes. So it sounds a lot like hydro when I hear bent rods. Maybe tie'ing into the fuel cut circuit of the computer and attaching it to the pump controller.. to kill the alky when fuel cut occurs? Or at least reduce it. Dont know if i'd want to kill the alky at 30 PSI ..

I agree more research is needed with the sticks... the automatics have not had this issue, but we dont bounce of the limiter every shift.

 

[Hyboost4Banger]

Yep. There is a pattern. All three of us are running lots of alky....with multiple nozzles. I am running a M-10 and M15, gain set @ 4.pm . Methanol sucker. (Outside temps were probably 35-45'f.) Each of us remarked how unbelivibly friggen' fast our cars were feeling right before it happened...(usually when stuff breaks).....and partly why I was hitting the rev limiter. I was getting all 4 tires to break loose in third gear on dry pavement @ 35 psi. Whoo!. ( What a ride. ) Scary thing for me is.....I was watching my palm like a hawk when it happened...no knock whatsoever. ???? I just assumed pre-ignition would show up as knock. Maybe not. If pre-ignition is not picked up like knock......then I also have reason to believe pre-ignition may be the problem.

I wonder if cutting the spark instead of fuel would solve this rev limit problem?

I doubt we were hydro-locking. More than likely just making too much power for the stock rods or pre-igniting ( you lucky V6 guys got two extra ones to spread out the load )

Overall I'm not too bummed. My block is intact. My stock 110k mile head gasket was going to go anyway. I knew it would. I ran all the way in the 11's (before alky) without ever even taking the valve cover off. The upgrade to ARP studs and forged internals was inevitible.

We learn as we go.



Mark