I've been toying with the idea of building a 400 TPI "torque monster" to replace my 305 TPI. My idea is to optimize the motor for low / mid torque to complement the TPI intake system. I already have the AS&M LTR's and ported plenum etc which could go on the 400. I am thinking of a fairly short duration cam with around 1/2 inch lift, aluminum L98 heads cleaned up and pocket ported, roller rockers etc. Max RPM around 5,500.

Do the L98 heads fit the 400 SBC? Do the later 400 motors have provision for a factory GM roller cam and lifters? (bolt holes for the 'spider') Will this combo work with my MAF sensor?

What do you think this setup would run over the 1/4 mile? My car is an 87 IROC with 700R4 and 3.45 gears.

 

Sounds like a nice idea...........
The main thing choking TPI is the manifold, so your gonna have to lose that Stock one, Id get a TPIS one or fully siamiese one......

Aluminum l98 heads on a 400....... I really dont think so...... The aluminum l98's have 58cc comb. chambers... this is what 305's have....

You really need at least 64cc prolly 76cc would be best..... id get aluminum heads on a 400 to help to keep it cool..... Some of the better TPI heads are AFR's, and twisted wedge heads

400's are no factory roller blocks, but you can buy a kit to put a roller cam in, but i dont have any experience in this field.....

your gonna need bigger fuel injectors, so that means your gonna need a new chip....... ed wright at www.fastchip.com is the place to go.......

Your maf sensor will function fine, but will limit intake air flow, so I suggest buying the maf in my sig, you will also need the custom chip to maximize performance

 

Also, 400's have to have steam holes drilled in the heads.....

 

Hey DUI, long time no see.

I will agree with Import that the 58cc L98 chambers are going to be quite small. But, if you will be changing pistons, then you can get the proper compression ratio (9.5-10.5 depending on the grades of gas available in Australia) by going "deep dish". In fact, this is preferred setup these days - even over flat tops.

But you should do some investigation first. You may find that the "dish" needed is not available or quite expensive.

Also, with TPI and a 406, you are most definitely going to "max the MAF" at a fairly low RPM. I'd predict somewhere between 4,000 - 4,500 rpm. You may wish to consider "swapping" to SD which can easily handle a large N/A SBC.

 

I did almost what you are describing. I used a lower rpm band to compensate for the TPI shortfall. Will write more to you later.