tpi on 400

will a tpi system fit on and work properly on a chevy small-block 400? cause i got wondering and isnt that block all most the same as a 350. i dont think it will.

The only problem I can really see with it is computer calibration. The 400 isn't a high-revving engine, so better intake runners aren't necessary. It should work, but you might need a special PROM for it.

you will absolutely need a prom tune and you would want to have upgraded runners, base, and ported plenum. 400 is gonna want to breath. But it should all bolt up as long as you have the right year heads for it all to bolt up to.

Keep in mind that porting the plenum makes it breathe on the high end, but somewhat kills performance on the lower end. Same thing applies for cylinder heads and intake runners.

A 400 utilizing the 5.565" connecting rods is not a good high-rev motor. Piston side-loading comes into play with the shorter rods. If you are building a high-rev motor, then stick with a 350 and go ahead and port the intake. The 400 as prepared from the factory also tends to run hot under high load due to the layout of the water jackets. There are tricks to getting these blocks to run cooler - NASCAR runs these 4.125" bore siamesed cylinder blocks, but with shorter strokes (3.33") for 358 CID. They obviously work well in that application, but then again look at the stroke and the length rods (6.00") they use.

Don't spend a lot of time trying to make the TPI flow better for a motor that's never going to use it. You can put larger runners on it, but that's as far as I'd go. The 400, as delivered by Chevrolet, was a torque motor pure and simple.

If you use later heads with centerbolt valve covers on your 400, make sure they have larger chambers (76cc) and you will also need to drill the steam holes between the cylinders. Look at your current heads for reference.

my car (which i bought today) has a 400 and its tpi. works great.....