wich would be better for TBI, I'm not looking for 500hp so which would be better

 

blow through, good luck with getting that to work with TBI,
theres really no way of tuning it, others have played around with the idea tho, try and search see what you find

 

What are some problems with getting it to work with a Tbi? I planned on doing the same thing. Using a holley 4 barrel tbi with a 749 ecm.

 

Draw thru:

You would have to use a 2-bar MAP sensor and put it between the turbo and intake, not between the TBI and the turbo like it would be if you used the stock vacuum port.

You would also need a turbo with special seals.

You could not use an intercooler.

Blow thru:

You have to modify the TBI for boost ( Easy, drill two small holes ). The holley 4 barrel tbi might not need any modification.
Use a 2-bar MAP-sensor or a progressive fuel pressure regulator.

You can use any turbo if the size is right.

You can use an intercooler.

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Conclusion : build a blow thru if you want to turbocharge it.

To make tuning easier you could use a non-stock ECU, like megasquirt. Tuning a blow-thru TBI is no different from tuning a TPI or any other multi port injection system.

 

Sorry I do not mean to hijack your post my hp goal is the same using a tbi.

Thanks JoBy for the feedback. How do you keep the air from leaking around the throttle shafts?

 

You will find the instructions om how to modify a TBI for boost in an installation manual for a Vortech supercharger kit.

http://www.vortechsuperchargers.com/support/

This is the instreuction for a GM Truck (1988-1993 7.4 TBI Truck/SUV). Look at page 16. Then you have to port a channel in the intake or the TBI so the new hole sees engine vacuum when the throttle is closed. In the Vortech kit that is done in the throttle body spacer block on page 15.

http://www.vortechsuperchargers.com/...gc4gg218im.pdf

 

Essentially, there are no advantages to draw through over blow through with a TBI (there are slight tuning advantages if it were a carb). The only real issue with blowing through one is to deliver enough fuel to the engine under boost. You have 3 choices:
- add fuel pressure with boost using an external RRFPR or FMU
- program the ECM (you’ll probably end up running the biggest injectors that you can find at a higher then stock pressure to have any chance keeping up with the boost
- use an auxiliary setup like vortech uses for their superchargers, a super fueler or something similar