I have a 399-cid SBC. It's a Dart Little M, 4.155 bose x 3.625 stroke, Eeagle crank, 6-inch Groden billet rods, Brodix 18 X SP heads with custom Self Racing oval parts with port intruder, port matched HV-1000 Dominator flange. The heads flow crazy numbers, like 420-ish (still looking for my flow sheet), and I can't recall the port volume. Motor dynos 825-850 depending on whose dyno you believe. I have been racing it for years on 38-32 nitrous tune, does OK - runs 5.30's at 2900lbs. I know I have way too much compression, cam, etc. I would expect to change those things but how suitable would these heads and intake be to boost? I have an opportunity to pick up a Precision ProMod 91mm turbo (or two). My intentions when I built this car (another fox body Mustang - maybe you've heard of them) was to ultimately go blower or turbo. Just not sure if I have a good basis for a boosted application or if I would need to go with different heads.

 

what is your current comp........if you are willing to go e85 or alky you may beable to just put a good cam in it and let it eat........



no joke though it would be a boost limited app a ton of guys due it .........high comp lower boost and plenty fast take a close look and listen to a x275 car they sound nasty no matter what ... thats because they run comp with turbo. most of those cars 60ft like nitrous cars, they are limited to what size turbos they can run so to make the power they build motors with higher than normal comp and limit boost so they can keep up with the pack.......a 1300hp nitrous car and a 1300 hp turbo car is not the same ride.....

- - - Updated - - -

what is your current comp........if you are willing to go e85 or alky you may beable to just put a good cam in it and let it eat........



no joke though it would be a boost limited app a ton of guys due it .........high comp lower boost and plenty fast take a close look and listen to a x275 car they sound nasty no matter what ... thats because they run comp with turbo. most of those cars 60ft like nitrous cars, they are limited to what size turbos they can run so to make the power they build motors with higher than normal comp and limit boost so they can keep up with the pack.......a 1300hp nitrous car and a 1300 hp turbo car is not the same ride.....

 

o 1 more thing are your current pistons a solid or hollow dome ...... if they are solid look into having some of the dome shaved

and when getting your came cut ask them about dynamic compression.......cranking comp is one thing but a cam can be cut to bleed of some of the dynamic comp as well all tricks of the trade

 

I was assuming new pistons and cam would be required. I'm at about 13:1 now with a flat top (BME custom pistone). My concerns were more with the head flow. With the big chamber volume and big valves (obviously if flowing > 400CFM), I am wondering if the velocity would drop off and just not be a good boosted head, and with the standard port lay-out (though spread some) if the heat between the siamesed exhaust valves would be too high. I've heard that's a big issue on SBC engines, and I do have a little exchange between those cylinders spraying is with about a 400 shot. I did drill and tap them and run A -6 coolant linne from the water pump (spacers) to the head in that region.