a460 heads comp ratio vs tfs streets

i have a 521 bbf thats currently running 74cc chamber trick flow heads the street head, and i am around 10.5 -1 comp. ratio. i would like to go to a procharger and i would also like to use the a460 heads with a 91cc chamber. what would my comp ratio be with the 91cc heads? i am looking to go to about 9-1.

i realize that i would have to use bbc exhaust headers which i already have in another project, 2 inch primaries into a 4 inch collector. i also realize that i would have to change the intake to use the a460 heads. whish currently my 521 is an efi unit with an edelbrock air gap and i wouldnt mind changing it anyways.

what i am looking to do is get around 900-1000hp at the crank on a dependable reliable motor and still run pump gas if possible, if not i will run race gas. the engine will be for a mud race truck that weighs about 5800lbs on military axles.

the current shortblock has a forged scat crank, forged rods, and forged probe pistons. another question i have is would i have to change the valves for piston clearance?

thanks for all the help!

The A460 heads have specific valve pierce points, so a piston change will be necessary.

what kind of fuel are you running? 10.5.1 can be done with a supercharger /turbo ect if you run a good fuel but your tune window is cut down.

id like to run 93 octane but i could run 110.

110 whould put you on the ragged edge and your tune would have to be on the nose. you could get get a dish piston and run a lower cr and call it good with that head and a supercharger you are going to make a ton of power.

what if i dropped to 8-10 lbs boost, how would that do? running on 110 race fuel. i could always keep the fuel injection to keep the fuel air right.

if you are good at tuneing and running a afr guage i say go for it you will be happy you did it just make shure you have a the right size injector i dont know what procharger you are looking at the f family or the pc family but you should be in the ball park of 1000 fwhp make shure that you have the fuel sytem to feed it to.

i talked to the tuner that dynoed my 521 and burned a chip for it and he said he could tune it for the procharger. wouldnt the efi system help keep the afr just right?

if i have to change the pistons and all to run the a460s i might as well just change them to lower the comp. ratio and keep what i have, tfs streets. i thought with the larger cc a460s i could get by without changing the pistons.

i am really looking for more of a torque type setup, id like to be around 1000hp and 900tq and keep it pretty reliable. the setup would be for my mud truck in my avatar.

what kind of fuel injection are you running stand alone or are you running something with a maf?

i am currently running a maf with a modified a9l setup from a 93 mustang. i just had it dynoed and had some problems with fueling i plan to upgrade to an aeromotive electric pump and i was going to get one large enough for a procharger setup.

i think you will be fine. they have piggy back unit for the a9l cool little unit heres a link for you to look at it.
http://www.andersonfordmotorsport.com/
Look at the PMS 4

FWIW, and I'm not saying it's as good of a head, but you can get Edelbrock RPM's in a 95cc without having to change pistons. They use the same valve layout as the TFS Streets and can be ported to make some decent power.