Has anyone had sucess with tuning a TPI with a radical cam and high compression? I have a 350 bored .060 with 12 to 1 compression Cam is .525 lift 305 Duration 110 LSA Please help

 

110lsa will be very hard to get to run right on a tpi, expecially if its a high compression motor with other mods

with that cam you might as well put a carb on there, or spend a lot of money getting someone to try to tune it for you.

its that, or tune it yourself. and from what ive heard from everywhere around in austin that does some sort of tuning, they tell me tpi is hard/crappy to tune. even the guy from corvette country that does tuning told me that

 

Tuning the older GM ecm's is a bit tough when compared to the newer pcm's and very few of the "big guys" have much experience with it due to the popularity of the LS1. Your best bet is to learn to do it yourself or be prepared to dish out 400$ plus to have some one dyno tune it.

The problem with big cams and fuel injection is that you end up with a very erratic map reading. It's not the end of the world and it's completely tunable. Their are guys on here running cams well into the 240* range. You just have to know the stategies involved.

In a nutshell you want to flatten out your timing and fuel curves in the idle area's. On really big cams you want to run open loop and disable the stock O2 sensor at idle as it won't be accurate with all the fresh air a lumpy cam introduces into the exhaust. Once you get the revs up a big cam motor acts just like a small cam motor, it's really only in the low revs where the engine is unefficent that you have problems. Carb's and even LS1's have the same problems they just adapt to them more easily.

 

i have read that long duration cams don't agree with tpi. i'll go look it up at home but i have a whole chapter in one of my books devoted to cam selection on tpi motors, and it was backwards of typical cam strategies. our cam needs to be aimed at port velocity, in other words aggresive ramps. if you think about the "tuned" part of tuned port, in other words, pulse resonance, an aggressive ramp is helpful. as it closes faster as well, it'll help to create the pulse that gives us that torque band.

 

Ignoring the ecm side of things, the resonant tuning of the TPI intake really does clash with a high rpm cam. It's simple really, longer runners move the resonant "peak" of the intake to a lower RPM. To give you an idea of how "low end" the TPI itake is tuned for just look at the runner length. Don't quote me on this, but TPI intake runners are right around 18" long while a performer RPM or HSR have around 6.5" runners.

On top of that the TPI runners are fairly small, I believe the intake runner is around 1.75" which is about half the flow area of an average carb intake. Because of this air flow is traveling at such a high speed it can really pack the cylinder at it's tuned rpm range, but restricts flow at higher rpm's.

In a nutshell, pick a cam that is going to make power in the 2500 to 5500 rpm range. Trying to make power above this point with a LTR setup is going to be counter productive

 

exactly. i've considered keeping tbi on the camaro just because of how cheap and simple it is to play with other power bands, intake swap with a cam and boom you have a different car. another thing to keep in mind, is gears, to go along with our long A** runners you need long gears to make up for the instant torque the would shred tires with a 4.11 grinder. you have to use a numerically low gear to make use of that kind of powerband or else you just burn off the line followed by a waltz down the last 1/8th mile..

what i've learned from my gta vs the rs camaro, is how well rounded these cars are from the factory, the suspension, even mine with 20 years and 150k miles on the clock, is still far and beyond the capability of the motor to overspeed. the rs is just a peppy ride, the gta is a whole different beast, even with a good 200 lb's on the camaro, it destroys.