[Shifter]

Maybe dumb question, but is there a point or RPM that is easier or harder on the engine...whether it's "too high" or "too low"?

 

[IHI]

Maybe dumb question, but is there a point or RPM that is easier or harder on the engine...whether it's "too high" or "too low"?

years back some of us local found (when sportsman allowed a button and 4 wheel line lock- aka poor man's transbrake) that we had to use adjustable msd pill so we could not push through the brakes....and I think it was anything below 2800rpm and the cars would load up/kill/backfire/cough when button was released.

No such thing as "too high" really since too high is taking pill out and going straight on convertor...which surprisingly a lot of people do.

 

[S350]

years back some of us local found (when sportsman allowed a button and 4 wheel line lock- aka poor man's transbrake) that we had to use adjustable msd pill so we could not push through the brakes....and I think it was anything below 2800rpm and the cars would load up/kill/backfire/cough when button was released.

No such thing as "too high" really since too high is taking pill out and going straight on convertor...which surprisingly a lot of people do.

My dad has used this setup for years in his car with a delay box. Has it set to around 1800-1900. Never really had any issues using it. Biggest thing was just making sure there was enough pump shot in it withthe low rpms.

 

[MichaelP]

In the rare times I race my car top bulb with a delay box I use the programmable rev limits as a poor man's SLE, with 2200 initial (any time I am on the trans brake), then 3500 for the launch (1 second before launch).

 

[crazees]

I leave on the mat with adjustable chip at 2200- 1.57 60ft no problem. I foot brake and much higher it wants to push through brakes.

 

[fendermender]

I leave on the mat with adjustable chip at 2200- 1.57 60ft no problem. I foot brake and much higher it wants to push through brakes.

Related question... when foot braking, would a lower RPM give a better 60 ft ? I have the 4wheel linelock setup and it did a 1.62 with 2 step set at 3500. The converter flashes to around 4500-5000. My buddy suggested dropping to 2500 to give a harder hit.

 

[Sprayin96ta]

Related question... when foot braking, would a lower RPM give a better 60 ft ? I have the 4wheel linelock setup and it did a 1.62 with 2 step set at 3500. The converter flashes to around 4500-5000. My buddy suggested dropping to 2500 to give a harder hit.

Depending on the converter, yes it should leave better. I leave at 2200 off the footbrake and it leaves higher/harder than 3500.

Lower the launch rpm, more flash you get. More flash equals getting into the powerband/torque quicker. My car is 3350lbs so it's critical to get it to 60ft. My car on gas would 60ft in the 1.30-1.31 range running 6.50. It's been a 29 before. All off the true footbrake.

 

[crazees]

Might slow rt slightly.

 

[jpatt87]

my car pops and cracks like crazy on a 3000 chip. Sounds really bad. was told it was to low of a chip so my 4000-4800 chips came today to try.

 

[bracketstang]

I can go as low as 1800 on my 2-step. I generally don't go lower than 2000 though. One bit of speculation I've read which I'm not sure is true or not is that being on the 2-step at a lower RPM puts more stress on the engine. That there's a danger of putting the engine in a frequency range where it can create reinforcing frequencies that vibrate the internals of the engine at dangerous levels. Like I said though, I have no idea if that is really true or not. I do know that with my car I also don't want to be on the 2-step any longer than 2 to 3 seconds at most. Any longer and strange things start to happen. My RT gets killed, the car stumbles, or the car goes into limp mode (drive by wire car) and I'll randomly be down on on power and then I have to coax the car back out of limp mode over a few runs or leaving the car off for awhile.

 

[Duner]

I put mine on the 2-step at 2800 - 3000 to let the converter flash to 4800 for a pretty good hit. It pops and farts and dumps raw fuel out the exhaust - but leaves with 18 psi of boost and 1.4 60' times @ 4200# race weight. My only issue is that it kills wide band O2 sensors that way.

 

[crazees]

Seems like some cars do pop and miss more than others. Don't know if different boxes do this or what. One car I have is OK down low, really doesn't sound any different than my other car at 3400. That car pops and misses like crazy below 2400, sounds bad enough that I won't drop it that low. Both msd6al.

 

[Sprayin96ta]

Might slow rt slightly.

Very well said. I should have added that in my comment. Don't m is about everyone else, my car is for every 200rpm (+/-) is worth around .015 in RT. If I leave at 3200 and I'm .490 red I drop down to 3000 and generally .005 to .008 (on paper)

 

[denn468]

The thing that you don't want to do is sit there on the chip too long. That will do more damage than high or low chip.

 

[acs55]

the more cyl. you have to cut to hold it lower is more misfires going on.
this cools the cyl down and can foul a plug .
alky dont like low chips unless you high compression and cyl psi .
its all in the combo .it can add wear on the rod bearings and oil .
my pump gas dont like below 2500.
the toilet needs a converter dump valve to stay lean enough to run a stop and or twostep