What are the pros and cons of running both and which is better? I'm just looking into future building and would like to know which would be better for a 383.
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CK5
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Tbi Vs Tpi
- Thread starter Babaganoosh
- Start date
Hossbaby50
3/4 ton status
I like my TPI. More power then TBI and runs to a higher RPM before loss of power. It is more expensive and a little more complicated but a multiport FI system will always be better then a throttle body system. For cheaper FI to run on a motor that you aren't looking for high RPM & max HP from you will be ok with TBI but TPI just looks cooler and runs harder. 
Harley
P.S. Therobzilla & I both run TPI. He runs MAP & I run MAF. A few guys on the other board have done TBI swaps also along with mine & Rob's TPI. There is lots of TPI related stuff in my past post history. Search TPI & my user name and a decent amount of stuff will come up.
Harley
P.S. Therobzilla & I both run TPI. He runs MAP & I run MAF. A few guys on the other board have done TBI swaps also along with mine & Rob's TPI. There is lots of TPI related stuff in my past post history. Search TPI & my user name and a decent amount of stuff will come up.
Thanks for the info Harley, I will have to look into your posts. I agree the tpi system does look cooler.
supersize75k5
OrganDonorRacing.com
tbi...simple..reliable, easy, less complicated, less money..oh and did I mention simple?
tpi...more power..more complicated, more parts, and more money, did I mention more power?
tpi...more power..more complicated, more parts, and more money, did I mention more power?
I seem to recall someone recently going on about how much TPI sucked in terms of power production... that it was a restrictive setup or something. I didn't understand this as the system was used on the Vettes and they seemed to get plenty out of it...
Anyone remember seeing that lately?
Anyone remember seeing that lately?
supersize75k5
OrganDonorRacing.com
tpi rocks, like I said..and others more more complicated.
Oh, I believe it... I was just wondering if anyone saw the other thread and could explain why someone thought it was a limited setup.
How's TPI compared to TBI on off-idle and low-end torque? How about those two versus a good Quadrajet?
TPI *is* restrictive. It was designed based on a 305 in the early 80's, no way GM foresaw the power that was over the horizon at that time.
Go look at the guys over on thirdgen.org, and look at the money they spend on aftermarket runners and throttle bodies in the quest to make more power. They wouldn't be spending that if it wasn't necessary. When they start getting real serious, they go with short runner setups.
To my knowledge, nothing anymore has runners near as long as TPI was.
It's a good setup, don't get me wrong, but it's restrictive when you start asking the engine to breathe better than what factory heads of the time allowed. If TPI power was so spectacular, L98 heads would be king right now. It certainly was spectacular compared to the numbers the stock TBI was putting out at the same time, but not when larger displacement or faster revving engines are in the cards.
If you are just going to drop it on a stock engine, it will perform fine, and certainly be a large step up from a carb, and to a lesser extent, TBI.
*All else being equal*, TPI will have better low end. Intake velocity has no bearing on the efficiency of fueling with TPI, like it does with a "wet" intake system, ala carb/TBI.
Go look at the guys over on thirdgen.org, and look at the money they spend on aftermarket runners and throttle bodies in the quest to make more power. They wouldn't be spending that if it wasn't necessary. When they start getting real serious, they go with short runner setups.
To my knowledge, nothing anymore has runners near as long as TPI was.
It's a good setup, don't get me wrong, but it's restrictive when you start asking the engine to breathe better than what factory heads of the time allowed. If TPI power was so spectacular, L98 heads would be king right now. It certainly was spectacular compared to the numbers the stock TBI was putting out at the same time, but not when larger displacement or faster revving engines are in the cards.
If you are just going to drop it on a stock engine, it will perform fine, and certainly be a large step up from a carb, and to a lesser extent, TBI.
*All else being equal*, TPI will have better low end. Intake velocity has no bearing on the efficiency of fueling with TPI, like it does with a "wet" intake system, ala carb/TBI.
I have been looking into this system.
http://www.retrotekspeed.com/produc...erjection-1-system/powerjection-1-system.html
Kinda spendy but no performance EFI is cheap.
I really dig the carb look.
http://www.retrotekspeed.com/produc...erjection-1-system/powerjection-1-system.html
Kinda spendy but no performance EFI is cheap.
I really dig the carb look.
supersize75k5
OrganDonorRacing.com
sorry that price is getting way to close to a junk yard 6.0 and reworked harness and more power
oh...and off the shelf parts! One reason I really like the tbi..parts are everywhere and it was used on a broad range of platforms.
Hossbaby50
3/4 ton status
TPI is restrictive but less so then TBI is. Stock TPI runs out of air at about 4800 RPM. On a 383 it will run out a little sooner. You can hog out the runner ports and hone everything out to make more flow though. TPI will have better lowend torque then TBI will also.
The bonus of TBI is that it is cheaper to install and a little easier to understand and keep running well.
I went from a stock Qjet on my 350 to TPI and DAMN!!! The TPI makes WAY more torque off-idle and thoughout the power range. Throttle response was
. IMO there is no comparison. It seriously felt like a 20-25% gain in power.
Harley
The bonus of TBI is that it is cheaper to install and a little easier to understand and keep running well.
I went from a stock Qjet on my 350 to TPI and DAMN!!! The TPI makes WAY more torque off-idle and thoughout the power range. Throttle response was
. IMO there is no comparison. It seriously felt like a 20-25% gain in power. Harley
TPI is restrictive but less so then TBI is. Stock TPI runs out of air at about 4800 RPM. On a 383 it will run out a little sooner. You can hog out the runner ports and hone everything out to make more flow though. TPI will have better lowend torque then TBI will also.
The bonus of TBI is that it is cheaper to install and a little easier to understand and keep running well.
I went from a stock Qjet on my 350 to TPI and DAMN!!! The TPI makes WAY more torque off-idle and thoughout the power range. Throttle response was
Harley
Well in theory, a more restrictive system will do that, because of the increased velocity in the ports. I know the effect is more pronounced when using a carb than EFI, but the effect should still be there.
That does make me want to consider TPI if I keep my V8 long-term.
