Its true... I did it more than once to be sure...

where is this TPI wall i always heard of? I just got the TPI fairly tuned in on the street and now im datalogging the WOT portion and tuning it up...

It pulls pretty good right up to 6K... I dont feel a WALL of any sort. in fact, everyone always says TPI is good for Idle-4500 RPMS, I have NO power below 2500 RPMS! If i punch it from a dead stop the thing gets up on the converter(stock) to about 1500 RPMS... and slowly moves to 2300-2500... then picks up like only a TPI can all the way to 6,000 rpms where i used to shift with my carb. it DOES feel strongest between 3500-5000, but it certainly doesnt fall on its face after that.

If you dont know my combo by now, here tell me what im missing out on? Cam is XE262 flat tappet, performer RPM heads, stock TPI (ported to death tho).

 

well, lets see.... well ported TPI set up, new heads, and semi large cam that probably raised the power level from 2k to 5.5k... the "wall" that is talked about is usualy with stock tpi, or mildly moddified. With a good port, heads, and cam all teamed up right.... TPI should do very well. It wont pull like the same 350 with lets say a HSR/LT1/Mini, but it will pull. good job on the car.... sounds like you got a sweet set up!
Alex

 

Glad it feels good to you. If you're happy with it then that's all that matters.

If you want to see factual info vs. your buttometer, put it on a chassis dyno and see how well it does between 5 and 6.

 

My L98 is stock (but boosted) and I definately feel 'The Wall'. Right around 4800 rpm the fun stops.

The worst is when you're at freeway speeds, mash the pedal to race and it downshifts to 2nd (right into 'The Wall'). Alot of noise and not going anywhere ....

 

Kingtal0n,

It's your cam. I had a LTR TPI system that revved to 6500rpms :lala: . But, keep in mind that you are talking about SOTP. If you dynoed your car you would find that horsepower leveled off at or before 5000rpms. That doesn't mean that the car isn't pulling past 5000rpms ... it's just that it's not creating MORE horsepower as RPM increases past 5000rpms.

To get a better look at stuff check out Mike Davis' dyno pages ...
http://www.eecis.udel.edu/~davis/z28/winter01/dyno/

This would make sense if you drove in a car with a MiniRam and compared it to your car.

Tim

 

It's also quite possible that you're not at the rpms you think you are. I haven't found many thirdgens that had accurate tachs. Mine are all off by at least 500 rpm at redline, and in every case, they indicate a higher-than-actual rpm.

 

My tach is off by 500rpms at idle and 1500rpms by 7000rpms.

Thanks to Moates' scanning software I'm no longer short shifting at 43-4400 rpm.

It's kind of cool though watching my tach rap out to 7000 rpms!

WOW!

 

ah, but my factory tach IS way off...

lucky for me, i have mr. data logger which tells me exactly where and when things occurs... thats what im going by..

and its true, it doesnt feel as strong from 5-6 as it does from 4-5.... and what you said makes sense, traxion, its still making power but its dropping off due to lack of AIR... makes perfect sense..

so would you all agree then that a Stealth ram would be a perfect match for my combo?

 

I still thought it was the runner length that put up that "wall" Hense the Tuned.

Butt dynos are weird. Just like the rest said, but it on a Chassis Dyno to *Tune your butt dyno* to the truth.

 

i cant wait to get my car on the dyno, its real hard finding peak power especially in an automatic. its gotta be done in 1:1 gear preferably and under load like a hill. i remember last fall i was doin about 125 down the highway in 4th gear at 5K and hit a hill 4500 is as high as that thing would go on the hill, flat ground itll go to 5k and then i shift to fifth, definitly has a lot of torque tho 5th gear pulls real good at wot shiftin from 4th

 

It's possible to get TPI to pull higher, TRAX is an example.

Is there any way to make the stock gauges more accurate??

 

Yeah my tach is way off. It read 6000 rpms at 3000 rpms. Mine is a digital dash in my 87 GTA, any ideas for that????