i have an 89 gta 350 tpi i want to put a 400 small block in with my tpi intake and my centerbolt heads. will this work and what will i need to get or modify to make this run good?

 

You will need to consider upgrading you intake components. The stock stuff will choke the 400.

 

Depending on how extreme youre wanting to go a ported plenum and base with larger runners will supply the volume. As far as the heads expertly ported stock iron L-98 heads will work to around 400 HP N/A , But to work on the 400 you will need some steam holes drilled in them, a good machine shop will be able to do this for ya, just provide the 400 gasket for them to use as a template. A very mild cam with this set-up will produce gobs and gobds of torque and sound very docile, but you could stand to go with a bigger cam and not notice any driveability problems (not real big , in the 220 .050 duration range 112 lobe sep, 500 lift ). As a note without porting your stuff out and adding bigger runners the car will still be much faster , but your full potential of the set-up will not be realized until the intakes volume and the heads flow are increased. Oh I forgot to add that the small chamber size on the L-98s will require you to use dished pistons to keep compression down enough for street pump gas. I would go with no smaler than a 20cc dish and a standard fel-pro 400 head gasket.
Perry

 

thanks alotbut what size injectors will be good

 

It depends upon the power level youre wanting, if you build it for N/A 400 HP the 24 #ers will be fine, if you go over 450 then I would move up to 30s or 32s , of course a good pump is also a must.