This is for a custom setup, non-tpi, but I would like to start with tpi or lt1 fuel rails to save time. The questions, is the spacing of injectors the same on tpi and lt1 fuel rails, forgetting about rail angles and crossover tubes? Do lt1 fuel rails have bigger inside diameter than TPI, will the lt1 rails allow me more flow? This will save me having to buy one of each for inspection.

 

Pretty sure the spacing is different on TPI vs LT1, since everyone doing the LT1 intake swap looks for and uses the LT1 rails.

Email John Milican, he's the LT1 intake swapper guru, he'd know for sure.

Also, I don't think there's and concern with flow within the rails.

 

I dunno why, but your post piqued my interest. Having a TPI rail and a LT1 intake bare - decided to check it out.

The injector spacing is the same when looked at front to back.

The crossover rails are indeed different, making the TPI "wider" though which is what mobythevan was referring to (I think).

As far as tube diameter, I don't see any way to measure this without cutting...which I wont do. LOL.

HTH!!

P.S. keep us updated - I love to see folks doing trick stuff using factory hardware.

 

I personally would go with some Fuel Rail stock and have it cut and drilled for your application. Makes it easier.

 

I am debating whether or not to buy fuel rail stock, but if I can buy lt1 fuel rails for around $30 and the spacing front to back for injectors is the same as tpi then I may do that. It seems easier to drill and tap stock rails for AN or pipe thread fittings on the fuel line/return side than to drill fuel rail stock for injector o-ring sealing. BTW, do you know if MSD still sells the injector boss drill bit for drilling my own rails? I looked around but didn't see them available anywhere. I didn't email MSD yet, but you guys might know.

 

I am not sure about the drill bit.
My friend had his rail drilled by a performance shop. he only has one rail since his Supra has an inline 6. Our friends father has a machine shop and they made the lower injector boss adaptors for the intake.