Need knowledge for 393

[Bug86gt]

Im in the process of building a 393 stroker. Trick flow twisted wedge heads. Mild cam. want to keep fuel injection in my 86 gt i know ill need around 42lb injectors but idk what throttle body size to use i have a 70 mm on my 302 now but im guessing that be to small. i would like to run trick flow r series intake. and fuel pump size im uncertained about. will a in-tank 255lph pump be ok? do i need to run a hole new fuel system or will stock from tank to front plumbing be ok? plan on using big fuel rails and regulator i would like to be around 500+ hp. I WANNA GO FAST!!! Open to any ideas and knowledge i can get but cant find anything on what im looking for. also would be converting from speed density to mass air be smart i know ill need a tune once its all done but is it worth the extra money to go that way. Its a street car but it needs to be wild

[Trojan Horse]

Originally Posted by Bug86gt

Im in the process of building a 393 stroker. Trick flow twisted wedge heads. Mild cam. want to keep fuel injection in my 86 gt i know ill need around 42lb injectors but idk what throttle body size to use i have a 70 mm on my 302 now but im guessing that be to small. i would like to run trick flow r series intake. and fuel pump size im uncertained about. will a in-tank 255lph pump be ok? do i need to run a hole new fuel system or will stock from tank to front plumbing be ok? plan on using big fuel rails and regulator i would like to be around 500+ hp. I WANNA GO FAST!!! Open to any ideas and knowledge i can get but cant find anything on what im looking for. also would be converting from speed density to mass air be smart i know ill need a tune once its all done but is it worth the extra money to go that way. Its a street car but it needs to be wild

The 70 or a 75MM TB should be able to supply all the air you will need unless you are building a high compression all out drag racing engine.


To size your fuel system you will need to figure out how many pounds of fuel you will need to supply, then size your fuel pump and lines accordingly. There are calculators on the net that you can find with Google to properly size your fuel system. Some of them may be listed in the Useful Info or Superchargers and Turbos sticky threads.


Definitely convert to MAF as the speed density will not be able to handle the differences in air flow from a stock 302 to the 393. You might be able to "make it work", but why bother when the MAF is so much more forgiving, adaptable and configurable.


You should also consider getting an AFM PMS and a Wideband O2 system to tune the engine with, otherwise you will be stuck going to the tuners whenever you make any changes or something gets out of whack.

[Bug86gt]

thank very much for the info. compression is 11:1 and cam is 570/585 285 duration something close to that cant remember right off the top of my head.

[Trojan Horse]

Originally Posted by Bug86gt

thank very much for the info. compression is 11:1 and cam is 570/585 285 duration something close to that cant remember right off the top of my head.

You are welcome.
The formulas to figure what you need are out there, albeit some are difficult to figure and understand.
If you have trouble, post up a link to the formula you are working with and your info and I will try to help you figure it out.

[Bug86gt]

Awesome I appreciate the help thanks