Im gettin a 1990 iroc 350 put into my car..its a L98 350..ok heres the deal.....Were going to put the TBI on first instead of the TPI...We just want to get that put together and are curious to see how the TBI will do..anyways, How much HP will I gain or lose by having the TBI instead of the TPI on there? What other advantages or disadvantages will there be?thanks.

 

is your car tpi or tbi now? if it is tpi i would put the whole tpi in the car before you try to start it. if your car is tbi, then you will need to swap engine harness when going to tpi. so basically what ever your car is now, will be the easiest way to get the car runnin rite. i think(not positive) tbi is like a 20 hp loss over tpi something like that. tpi 350 is 215 hp? i think???anyone else help?

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87 z28 bowtie aluminum 420small block dry sump crower lt. wt. knife edged crank oliver lt wt rods brodix track 1's super ram intake slp 1 3/4 headers accel dfi art carr 700 r4 3.42 gears ssm sub frame/ladder bars.....other parts on the way ,soon to be finished!! couple more weeks!!!

 

the car is a TBI now....yes thats why were putting the TBI on the 350 because it will be easier.I guess a 20 HP loss wouldnt be that bad.Ive got the ECM wiring harness and everything for the TPI.its just that its all apart and needs to be put back together and cleaned up.I wonder what all that would be worth if i decided to sell it.

 

Darb,

My guess is that you will lose some torque at the lower RPM ranges, but since you are installing a 350 in place of a presumably smaller engine, you'll really be gaining torque.

On the other end of the scale, if you build for higher RPM operation, the TBI can effectively feed the 350 into much higher RPM ranges than the TPI. A higher flowing TBI on a good carb manifold will replace some of the lost low-end torque, and walk past most TPIs at 5,000 + RPM. You'll have to use the correct PROM for a TBI350, but those should be available from used Caprice SEO/police vehicles and several truck models. A 1992 cop car would be a good starting point.

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Later,
Vader
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"Get UP - Drop the bombshell!"
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Vader is correct that there is a LOT you can do with TBI and potentially should offer better performance at high rpm (over TPI) if setup right.

I haven't checked my "ECM X-ref" charts to see if the Police 350 ECM is the same as the TBI 305 but I believe they are. You will have to either alter the eprom or change the injectors in the TBI however to account for the Police 350s larger injectors.

 

thanks guys....I appreciate the help.All I know is I miss my car,hopefully I'll get it back tomorrow...but for $300 for doing the engine and $75 for the heater core...he can take his time.