ive got a 88 k5 with 350tbi in it now, what kind of gains will i see if i go to tpi? is it worth doing or should i just stay with my current tbi setup?
CK5
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tbi to tpi: worth it?
- Thread starter muddybuddy
- Start date
Thunder
3/4 ton status
If you change the heads and cam I guess it would be worth it to get more power as long as you can pick up a complete TPI setup for real cheap.
If you keep your TBI heads and cam. No it is not worth it.
If you keep your TBI heads and cam. No it is not worth it.
I suspect that in actuality TPI is going to be MORE restrictive at higher RPM's than TBI. I think flow is about the same through the TPI/SB TBI throttle bodies, but the runners on TPI are pretty restrictive.
At low engine RPM's the TPI should make a bit more power, simply due to the fact that the intake is "dry". Fuel distribution at all RPM's should be slightly more even with TPI if the injectors are in spec, but that's almost impossible to know for sure.
Agree that the combination is going to be a major factor in what kind of gains you see. Note that the long, small diameter runner design of TPI isn't used anymore, that should tell you something.
At low engine RPM's the TPI should make a bit more power, simply due to the fact that the intake is "dry". Fuel distribution at all RPM's should be slightly more even with TPI if the injectors are in spec, but that's almost impossible to know for sure.
Agree that the combination is going to be a major factor in what kind of gains you see. Note that the long, small diameter runner design of TPI isn't used anymore, that should tell you something.
so unless i plan to basically upgrade my entire top-end to maximize gains, then converting to tpi isnt worth it? the motors got 125k on it, i duno whats gona happen when it goes, most likely a another sbc
Unless it was cheap or free to do, I don't think I would. The "1986" in my sig is leaps and bounds stronger than the 1987, but I've got different heads, cam, roller lifters, roller rockers, headers, you name it. Without all that, I'm not sure the TBI/TPI difference would be that noticeable, especially if you didn't change the cam and heads.
The real step up is the LS-series motors. They make more power everywhere, with better mileage, than the Gen1 SBC will ever be capable of.
The real step up is the LS-series motors. They make more power everywhere, with better mileage, than the Gen1 SBC will ever be capable of.
smalltowncowboy
1/2 ton status
i am starting to do research on TPI engines cause im picking one up as a trade. 0 miles, crate 454TPI, with harness, computer, high torque starter, headers. has the complete build sheet from a fairly local dealer (sallee chevrolet).
trading an old carbed 454 with a bsted th350 and good 205. straight across trade with a friend.
trading an old carbed 454 with a bsted th350 and good 205. straight across trade with a friend.
No such thing as a "TPI" 454, curious to see what it turns out to be. Maybe something controlled by a TPI computer?
Only the 305/350's were TPI.
Only the 305/350's were TPI.
smalltowncowboy
1/2 ton status
well hes got the build sheet on it so we will see when i go over to his house
smalltowncowboy
1/2 ton status
454-502 Automotive TPI System w/ GM ECU & Harness. The ASM big block tuned port injection is designed for any cubic inch big block Chevy engine, oval or rectangle port, short or tall runner, we have them to fit any combination. The basic unit consists of a lower manifold assembled with the 30 lb./hr injectors, fuel rails and fuel regulator, upper plenum with linkage assembly, 58mm throttle body, GM computer with a custom program, complete wiring harness, all sensors, distributor and coil, high pressure fuel pump, K&N high flow air cleaner, and all mounting hardware
this is a 454 tpi kit i know. but this might be what he got from the dealer. they deal in high performance stuff for around here. i know the motor cost him like $4500 with everything
this is a 454 tpi kit i know. but this might be what he got from the dealer. they deal in high performance stuff for around here. i know the motor cost him like $4500 with everything
GM never made any big block tuned port runner stuff, that's whats making me scratch my head.
http://www.azspeed-marine.com/asminzz.html
Ok, so looks like ASM created a tuned port setup for it. Gotta be pricey new, even $4500 sounds cheap!
http://www.azspeed-marine.com/asminzz.html
Ok, so looks like ASM created a tuned port setup for it. Gotta be pricey new, even $4500 sounds cheap!
smalltowncowboy
1/2 ton status
i found out that chevy made about 3500 of these engines. TPI 454's they were made but were never installed in anything from the factory. they were a replacement for the 454 TBI. they were also installed in some of the commercial vans on special order.sallee chevrolet had 15 of them in stock when he bought this one, theres one for sale in la grande oregon with 55000 miles on it with a tranny from a wrecked commercial van.heres a pic. (cell phone pic)
That picture is of a Vortec 7.4l from a 96-00 california truck.
Thunder
3/4 ton status
Looks llike a Vortec 7.4 to me too.
TPI throttle body is on the front of the manifold not the side.
TPI throttle body is on the front of the manifold not the side.
