I ran a 1/4 strip that everyone in town uses for a drag strip, and the car ran great(except for spinning thru about 40mph) but when i crossed the finish line, my car was pushing 5700RPM's in 3rd!
isnt the peak power on tpi around 4500-4800?
I wasnt about to shift into OD at fullthrottle(corvette servo)
i was running 111 mph, and 12.44

do i need to go back to the original 3:23's or go to taller tires>??

I cant see spending $1000 plus just to get my intake setup into the 5500 powerrange.

I know most factory 350 tpis came with 2:73-3:23 gears. im assuming that was to keep them from turning past the power band.

anyone??

 

I am assuming that you have street tires that are about 26".

If you are spinning out of the hole, get bigger tires(28")
Then you will be closer at crossing the finish line at a lower rpm.

 

hummmm. I was told to go with 3.73 gears so that I would still be in 3rd gear at the end of the 1/4 mile....Is this wrong? If your at 5700rpms with 3.42's.....I will be even higher then that with 3.73's.

 

He says he is running 111 MPH so his RPM will be higher, unless you are expecting to run 111 in the 1/4 mile. It takes a lot to run 111 MPH in the 1/4 mile.

 

I'd try bigger tires before you consider whether to step down to lower rear gears. See how it likes that change before you decide. May help, may hurt, may make no diffrerence. 5700 isn't very far outside a modified TPIs usable power band.

 

but he does say he has stock setup. if that is true and if he does spend the money to get the intake breathing a little better. he'd be in the 11s for sure, or at least 12.0. i must say man your car is sick if your running that fast with the stock intake. i dont think i recall anyone doing that, or really even trying it now that i think of it.

but for your question go with bigger tires first, like damon said. or you could just try some drag radials.

 

well i have 26's on it now, and i tried some 27/10 goodyear pulloffs,but i didnt know if that was too much tire, i mean the car chirps on take off, but i dont wanna lug the gearing too much. know of a good street tire for going bigger?
255/60/15 maybe?
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btw, hows that 06 R/T run?

 

It's my wife's, but when I did put it on the g-tech it ran a 14.4 in the 1/4.

If you try bigger tires and get to a track, tell us how it goes!
I very curious!

 

Is That 5700 rpms on the stock tach or an aftermarket one?

 

your "zz4 350" is actually just the cam, in a stock 350 TPI motor? wanna make sure i'm on the same page.

any sort of aftermarket converter?

I wouldn't bother swapping gears, much more hassle than just throwing a little taller drag radial on there. plus its reversible.

 

Like Will elluded to,,, there's a good chance your tach is off. You should be going through around 5,000 at 111 mph with 26" tires, 3.42s, and a typical 10" stall converter. Regardless,, cudos on the et and MPH, and I'd borrow someone's tach before I put much more thought in changing gears and changing tire height.

 

i was using my scantool for rpm, and mph, as stated, the factory equipments a little off! Im running a stock converter, i am running a trans cooler,but its an everyday driver, i want to keep the heat down!

Tobias, you are correct, i am running a .30 350 from an 89 z71, i had it balanced and put a zz4 cam in.

I did some mild port matching on the intake but nothin serious, i prefer velocity over volume.

I would love to get a stealthram and some aftermarket heads, but for the money, i seriously think the stock setup is underrated. as long as you get your gearing right for the powerband, you wont overrev the engine!

for the money you could take a stock 5.7 tpi, put a cam in some mild head work and break 12's with stock gearing, instead of trying to put a 6000rpm cam in and build EVRYTHING else to come up to that level, is a few more horses worth $2-4 grand? only if it goes to the track
i was running a 12.8, but i got some better times after turning the afpr down and readjusting the timing, and it still seems to get decent mileage
it still runs rich at cold start, but im hoping to do a 870-730 ecm swap before long, i believe the MAF system is restricted to about 440 CFM's of aifflow, talk about a bottleneck!

anyone done the swap before?

 

Ok,, I read your original post again and see this was not at a track,,, some strip of road where you used some sort of accelerometer like a g-tech while scanning it?? If so,, you need to take it to the track and get an accurate mph and et and see what's off in this equation. 111mph should be around 5000 rpm unless your converter is slipping VERY badly. Typically with everything working properly,,, 5700 rpm with 3.42s in 3rd would put you at almost 130 mph in the quarter mile,, so something is screwy.

 

I'll add to BadSS's question...if this is some strip of road you're racing on, are you're sure it's exactly a 1/4 mile and not a little longer (or downhill, etc etc)?

Also, what size and kind of tire are you running?

 

the strip was measured off twice, and came out to the exact same marks for 1320 feet, its on a flat level highway.
the tires i am running currently are regul sport challengers 235/60/15, there 26 inches new, from the looks of a tire size chart:
TIre Height Chart ,

I need to go with either a 255-60-15, or a 305-50-15 to get my ratio about right. I was running a set of factory offset 16 in. iroc wheels,but the staggered backspacing was causing tire rub, and even with goodyear eagles, it was not sticking in the corners, with the regul 15's, i can take hard corners at 100, without as much as a chirp and the backspacing is the same with my eagle alloys!!!

the iroc wheels are great for a car that doesnt need much traction, they were great on my lb9 with airbox mods,k&n's flows and ecm bypass(*******!)
but with the 350, theyre useless

 

What are you using to get your time and mph on this strip?

 

You know,,, unless he takes it to a real track to get the real et and mph,,,, it doesn't even matter. It might as well been the second hand on his wrist watch.

 

LOL it's pretty obvious he is not running a stock 350 with a TPI and a mild cam to low 12s at 111 mph at a track.

 

I was gonna say ....

I have a 350 ( 30 over) with the ZZ4 camshaft ...and all the stuff in my sig . I get a 14.4@95 with it ( yeah I never mastered the launch 2.2 60ft) Untunned it netted me with 251 rwhp and 319 rwtq. Thats with the vette prom ( APYP) . I don't see you anywhere near 12's . But let us know what it does at a real track ....I am curious how you made out .

 

Just read through this and I too was surprised at first, and no offense but doubtful of the 1/4 times with a ZZ4 TPI. I have a true ZZ4 and with 3.73's it's a little over 5K crossing the line in third. It actually could use a few hundred more rpm then the ported TPI is allowing, but rpm wise it's about right. That's with running 26x10.5 M/T ET Streets. You can see the sig for more detailed mods but I ran in the high 12's and that's at about sea level. I think it has a bit more in it but not much. I haven't been to the track in a looooong time, I wish there was one closer then NJ. Stupid LI!!!!!

 

Is that with a 5 speed ? I am crossing ( sure at a lower et at the moment ) but I am crossing in 4th at over 4000ish ( not sure exactly what now ) thats witht a 5 speed and 3.73's . I don't see how I would ever cross at 5000 in 3rd ....not with the 5 speed and 3.73's

 

i'd say thats way beyond. i wouldnt take a fully modded TPI past 5000-5200. 5500 is a stretch for chopped up fully siamesed rewelded TPI runners. stock TPI kicks at 4200-4300. mine showed around 4100 but i think the run was flawed since i might have had my EST wire disconnected lol

anyway, no way in hell a zz4 with stock TPI is doing 111mph and 12s. my buddies SS dynos 333 and hes doin mid 12's at 110. and like said, its not gonna be 5700rpms at 111mph with 26 inch tires. zz4 is rated 355 but thats with a highflowin carb intake. TPI is weak. TPI will knock off 50hp off the bat on that motor. scoggin dickey had to add LT4 hot cam, higher flowin vortec heads and aftermarket edelbrock TPI to get the ratin back to 357hp on zz4 bottom end

typical zz4 cammed bolt on TPI cars run mid higher 13s. setup right they should go lower 13s cuz i do close to 13.6s now with stock L98 with exhaust/stall/3.42s.

so something is not right here

 

You say "a 1/4 mile strip," So am I to assume that this is not a real drag strip that you are running your car are on? A zz4 motor should, as previously stated, be a plain L98 engine witha zz4 cam and an unported tpi setup. So you have a mildly done engine and are running a 12.4 1/4 mile and know exactly what RPM you are crossing the line at? I am finding this very hard to swallow. Does nobody else find this hard to believe that many other well known people on here have engines with much more done to them and are running around the same times?

 

not surprised at all...it wont happen. base ZZ4 with carb will have a HARD time gettin to 12.4 with full weight thirdgen. actually might not be possible

 

It appears that we are the sane people in a crazy world.

Back to topic though, I believe that you have much more to worry about before you can work on the finer points of your 1/4 mile time. Do not waste your time on a set of lower gears. Get a different stall, better flowing intake, better suspension and start your own tuning. Who knows, you might actually be running 12.4 on a real dragstrip by then.

 

Got fresh tires on teh car last weekend. and the first time I really got on it, the car spun hard,but launched better, when it barked 2nd, i heard a loud POP!! let off of the throttle, adn eased it home, jacked it up,and, the fairly new bushing for the torq arm, is in pieces! where can i get a better torq arm, and a stronger bushing?

cars finally trying to hook with fresh rubber,and now,this,lol aint nuthin but a small pitstop on the way to speed!

im gonna shoot for going to red river raceway after christmas, new jobs, stranggling my time right now!

its the only 1/4 miles track for a lil over 100 miles(prescott is only 1/8 mile)

right now putting new energy suspension bushing throughout, and getting paint

i'll try to repost as soon as i get some results

any suggestions on a stoughter torq arm, the factory one, looks like its paper thin!!, i already have subframe connectors, so i guess this was just inevitable!!! its only as strong as its weakest link!!