im not sure if this is the right forum but i was wondering if i could change out my tbi manifold for a tpi manifold? i want to do this so that it will be easier for me me to build my own custom ram air system. has anyone done this? what all would i need? any help is appreciatted. thanks.

-nick

 

You have to do a whole lot more than the manifold. you need to change everything over. I don't know that it would be worth changing over a TBI car to TPI if you had to go out and pay the going rate for TPI components. However, if your looking for more you can always go with an aftermarket FI setup.

As far as I know the base plates aren't the same at all.

 

well i still want to try and do the swap....does anyone know if this is all i need and if it will work...is it worth the price?

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2414547299

thanks.

 

You still would need all the wiring. To go from TBI to TPI you have to replace pretty much all the wiring in the engine bay and the ECM. On that auction, I don't really know the going price for a TPI setup but I would not spend more than 300 on that and 180 for the harness and ECM.

 

What are you putting this onto? If it is a 350 make sure you buy a complete setup that came off a 350. There is a difference. The computer will be different which you may have to reprogram a chip for it anyway. The injectors are also different.

 

You are going to need a lot more than what is in that auction. You will still need a MAF sensor, all the parts for the intake.

 

Nikester......... i am in the middle of doing this.......Let me give you some very important advice.....Don't buy a tuned port system off of ebay... Find donor car to take it off of. I can't tell you how many times i had to run back to the car i pulled my tpi set up off of. Theres alway a nut, bolt,sensor or relay that gets over looked until you actually get your head into this thing. Not to mention if i couldn't go back, this would have been really ,really expensive. Trust me on this one.

 

true im piecing it together as we speak. no matter how many parts you get with a "complete" tpi, there are always more...

like for instance no one mentioned the stock TBI throttle cable / TV cable would reach the TPI throttle body.

and no one mentioned i would need my own braided fuel line because the TBI ran to the back of the manifold, TPI rails end at the front for fuel.

and no one mentioned my darn knock sensor was differnent for a 350, i had a 305.

somone DID mention that the fuel pumps are WAY differnet, but no one mentioned how HARD it was to change a darn intank fuel pump!!! arrg!!!

lots of little crap. i could go on forever. I started gathering pieces about 2 months ago, and $800 later, im still gathering. right now i need the air intake ducting to mount the MAF so the computer can see how much air is flowing in. I also need the programmer because i dont have a stock 350 to just drop in and run. theres another $250 right there. *sigh expect to pay about $1100 or more for just a dead stock TPI setup., installed and running....


but in the end, it will be worth it. i cant wait to see my torque curve now, and with 3.73's, ill be all over the street.

 

The ECMs in a 350 is the same as an ECM in a 305. It'll either be a '730 ECM or a '165 ECM. '730 ECMs were used for SPEED DENSITY systems, which dont require the use of a Mass Air Flow sensor (the black tubular looking sensor that is in the intake path). I'd highly reccomend getting a '730 ECM so you dont have to deal with the MAF Sensor.

http://search.ebay.com/search/search...&query=TPI+ECM

Most, is not all, of the eBay auctions you'll see will say "Memcal not included" You'll need to purchase the 350 AUJP memcal from GMPartsDirect.com, part #16151348. That number is for AN AUTOMATIC CAR, I do not know the # for a manual car.

I purcahsed a new GM Speed Density Wiring Harness for my swap (in progress). I'm sure a used one would work, but I dont know if I'd trust it. I got the GM harness because it includes ALL the wires for every sensor in the stock location. I've heard of people running into problems with the Painless TPI harness, and I didnt want to bother with that. Hope that helped!

 

Actually I was talking about the PROM being different. The ECM will be the same. Also, there are more that just the '730 and the '165. Be careful not to get and ECM from and '85 Iroc. Those came with the '870.