We all know tpi chokes at high rpm, but if i put a turbo in will it still choke. I am looking to get the best bang for my buck and boosting seems to be the way to go. I am very happy with my take off but I want more power 30+ mph any other suggestions would be appriciated. This probably has been answered if someone knows where the thread is that would be great also.

 

turbo tpi motors typically have the same power curve as na tpi engines just alot more of it,

power will start falling off at around 5,400 rpms and will be all done by 6,000 rpms

turbotpi has gone low 10's with the tpi and turbo355 has gone low 9's with a basically stock tpi setup, im pretty sure all he did was remove the egr bumps and gasket match the tpi.

i have only done gasket matching on mine and im looking to run low 9's with mine and twin 57mm turbos

 

So just putting a turbo on it will change 1/4 mile times that much.

 

Is there a way to do a turbo without tuning I cant find anyone locally that will tune my car

 

theres alot more to it then just bolting on a turbo. check out z3astros build thread i think his car was doing 12's on a stock motor at 12 pounds of boost

 

The stock TPI system is essentially finished after 4000-RPM with both 305's and 350's. Siamese the TPI system and your RPM's will increase substantially, just be sure to select the proper camshaft to take advantage of it. I siamesed my stock TPI system, installed a 224/230 camshaft, and RPM's now shoot to well over 6000 almost immediately. Prior to this they had trouble getting passed 4000-PM on the highway, and this was without the turbo during both instances....

 

Maybe a mild cam is the way I should go if it gives a little more in higher rpms

 

It really depends on how you size things.

Most stock TPI 350's run fastest when you shift them around 4600-4800 rpm, where the 305's can get into the low 5Krpm range before they really run out of breath.

Add forced induction to make up for the airflow short commings and you can use it to extend the rpm range, but most people size the turbo and the cam to still work best in the stock range. That is the most reasonable approach, but the problem with it is that on shifts your RPM drops below the NA torque peak and it becomes fairly difficult to run higher boost and control detonation.

You could size things to work past the NA rpm range and use the extra air from the turbo to make up for the deficiencies of the intake and extend the rpm range. That not only lets you run more rpm, but also allows you to run more boost at WOT, but does require much more careful part throttle tuning.

With a stock TPI setup (minor clean up) on a 350 there is no good reason why you couldn't reliably push 15-20psi boost to the mid/high 5xxxrpm range and close to 800bhp, assuming that you have the right engine combination under the intake. On a stock TPI engine you'll run out of heads and cam before you'll run out of intake airflow.

 

thank you for the info. What about the electric supercharger that on ebay for $50 has anyone tried it. I can see how it will work but dont see how it will spool up enough without putting a drain on the electrical system.

 

LOL NOOOOOOOO

 

Procharger is the only way to push TPI....as the boost goes up it has no choice but to get off its a33 and move out the way.

 

I went to the extreme with my TPI setup, as I siamesed everything, and opened it up to the maximum. I did this because of the turbo and stall that I'm running, as RPM down low has now become meaningless to me, I don't even see it anymore. My advice to you with whatever cam you decide on would be to work on the lower intake only. Leave the runners, plenum and throttle body alone. Open up the lower intake ports on the manifold leading to the cylinder heads, then siamese the runner entry ports on the manifold as well. This allows for each combustion chamber to pull air from both sides of the runners, and not just one. Do nothing else as it would be completely overkill, trust me on this...

 

Turbo + short runner intake will get you alot more rpm. Stock L98 cam is good to 5200 rpm and shift by 5500, although its dropping off pretty fast after 5200. Turbo/blower may help extend that point alittle longer. So basically its about 1000 rpm more available over stock TPI. AFtermarket TPI can also help with its larger tube diameter, it can extend rpm alittle on stock cam/stock heads as well. Siamesed TPI acts like a shorter runner intake like stealth ram or miniram so it also extends rpm range.