mods: removed top off intake, aftermarket drop in air filter, tb mod, port matched manifolds, removed 5th and 6th port sleeves, advanced ignition timing, 2.5 inch exhaust single exit(stock manifold). maybe some other things i forgot,

when i accelerate hard everything is all good until i hit 7,800rpm, it feels like my car hits a brick wall, it starts backfiring and bucking, it wont go past 7800, WHY???

am i hitting fuel cut??? if so why? do i have fuel cut? is it ignition? https://www.nopistons.com/forums/pub...1047683561.gif



oh all emisions are gone a/c p/s air pump, acv, rats nest, all gone, also omp is gone, premix exclusevly

seal float?, motor might be tired. Time to pull it and give it to Ito!

My guess would be the fuel cut, maybe your tach is off. My tach is/was off in my AE by almost 400 rpm. And if thats the case with your car you'd be hitting the fuel cut.

my stock tach is showing 200rpm higher (or lowerr i dont remember now lol) than it is,

but i also have an autometer on my dash that one is the one i refer to, and @7,800 on the autometer it craps out

They do have a rev limiter, don't know exactly at what rpm. These engine like to keep reving non stop if it wasn't for it.

the s4 ecu runs out of processor speed at about 8krpms, so its like a revlimiter



mike

i hit fuel cut in my 89 GTU many times. it was around 8200-8400rpm indicated

Is there a neccessity to rev the engine up that high? Isn't max horse power at 6,500? Wouldn't it be slower if you over rev it like that?

Because we can. https://www.nopistons.com/forums/pub...#>/biggrin.png

i like to rev high because it sounds FREAKIN awesome, and my power doesnt run out til about 7500rpm, it still pulls though and then comes 7800 and it hits a brick wall, lol

when i raced if i revved high enough it eliminated an extra shift in the 1/4 thus lowering my overall time...................

fuk, if i could i woud rev to 11k

which will be possible when i pull my engine and do the rebuild and bridge port it, or maybe peri port dont know yet

dude...i have the same problem...in my 91 n/a...i always did...cut off around 7500...



and THEN...one day a mustang lightly rear-ended me...but it was enough to give the car a good shake. And GUESS WHAT! after that for 2 months it RAN FLAWLESSLY...pulling up to 8500 with ease...I was stocked!



And then after about 2 months it seemed to drop back to its lazy ways...i've tried a few things...but haven't tried all the options...

nope, by leaving it in a lower gear you still get more torque to the rear wheels, which give more acceleration than shifting to a higher gear, which puts your engine at a lower rpm (reduced torque) and lower gear ratio in the tranny (more reduced torque).



this is the same reason that the rx-8 has a 0-60 in only 5.9 sec, and only has 159 ft-lb of torque. it can leave it in a lower gear till 9K, putting more torque to the ground through the transfer system (drive train).

Fuel cut or the rev limiter.