seventhgear

Hello. this is my first post.
I have a SERIOUS question.... I currently own a 1996 cobra.
I have almost every bolt-on you can buy this side of the Prime Meridian. lol well any ways.....i would like to make 450rwhp (with also an additional 150-200 shot of nitrous)
Ideally i would like to use my stock block to build on seeing that i have heard the crank and block can hold 600hp. Yet, if i cannot use the block it is quite alright.The only internal mod i have is Sean Hyland stage 2 cams.(makes power from 5k-8k)
i would like to get some input from you guys to figure out the best piston/rod/heads/intake mani. etc. combo.
i was told to achieve this it would take 11.5:1 comp pistons @ the very MINIMAL.
I WOULD LIKE TO RUN PUMP GAS.

would i need an aftermarket intake mani.? if so, who makes one for the 4v?
would i need to port/polish the stock heads? buy new heads?
blah blah.

i did a search and could'nt find any good info so maybe you guys can lend a helping hand
thanks in advance!!!!

Mustang3GT07

Please list your mods. Do you have a supercharger or do you plan on getting one?

limp1969

n/a or power adder? with a turbo or super charger pretty easy find a 03 04 cobra motor and bolt it in. You would need around 550 hp at the crank to make that rwhp. if N/A you would have to goto a higher compression which would then need higher octane. A turbo is really nice but $$ you can set the boost on the fly. If you want to use it as a DD lower the boost use pump gas if you want to race, up the boost use race gas.

With a super charger you are stuck with the boost. I really like the idea of a N/A motor.
Dont know if there are stroker kits for 4.6 motors or not but that might be a way to get close.
Porting, cams and the highest compression you can go on pump gas. Remember there is static comp. and dynamic. With the correct cam choice you maybe able to run a higher comp on pump gas. My 428scj is 11.7:1 and runs on pump gas with no problem it makes 410rwhp. When building the 428 back to stock I got a good lesson in cam choice.

I would ask an engine builder that builds modular engines and see what you can get out of one on pump gas. My guess would be some where around 425hp at the fly wheel.
- around 18-20% when it gets to the pavement. That puts you down alot. And I would guess that engine would be alot of $$.

I know a few engine builders in Southern Cal. A shop next to me install a 02 2 valve twin turbo engine built by power heads. It made something like 750rwhp. I beat it cost over $25k.
http://www.youtube.com/watch?v=yCI_XqL4FcY

seventhgear

i thought i mentioned that i would like to go N/A.... sorry
yes i just wanted to get some input on the matter. i have been doing a lot of research and i believe 12.5:1 is the the way to do it... i will have 1 power adder(nitrous) like i said in the first post, but i want that for a lil extra. from what im understanding my heads flow VERY well. i am hearing that i have to do nothing to them, yet my intake manifold on the other hand lacks velocity.
there are no aftermarket IM's for my heads , but there are some for the 97+ models. so i may change to those heads which is like(15-25)cfm difference and go that route. keep my stage 2 sean hyland cams stud the top/bottom end, balance my crank,pistons/rods, injectors,and also some really good gaskets. and see what i can pull outta that. i was told maybe 350-400 @8100rpm or so on pump gas. but that is twisting that motor a tad high.... i would like to stay at or around 7500rpm and just use spray. i hear the 5.4 navigator heads flow really well, but i'd have to get the 5.4 block. so there is a bit of thinking to do........

any more input would be appreciated... thanks to those that already have given me thier .02.....

limp1969

Sounds like you might be drag racing with that set up? And yet be streetable. I like that.
What is the gas octane ratings in your neck of the woods? Here in CA 87, 89 and 91.

On the heads your using what is flow cfm on the ports?

seventhgear

octane: 87/89/93

i found the exaCT NUMBERS yet i am not able to find them again. from what i have read the 96-98 4v heads flow a lil more cfm than the 99+ 4v heads yet, no one makes an aftermarket intake for a 96-98 so the simple choice would be 99+ for me...

seventhgear

the cams i am using need a bit more velocity in the intake department so the 99+ aftermarket intake mani's will do just that

limp1969

do you no the cfm flow #s for 96-98 heads?

seventhgear

LIKE I SAID IN THEPREVIOUS POSTS
i read the cfm #'s before ..... i know they are close to being the same as the 99+ heads.
but i do not remember the exact #'s
sorry man... maybe someone can pull em up for me...

SVTeeshirt

im doing a very similar project but without Nitrous, im going C heads which are much better for N/A applications, the 03/04 cobra heads flow too much, better for f/i, with these cams...http://www.jegs.com/i/Comp+Cams/249/106200/10002/-1 and i'll probably go with a 99/01 cobra intake manifold not too sure, im going diamond pistons and rods probably with close to 12.5 Compression i also am staying pump gas, if i can get 400whp im happy with that and a set of 4.10s i already have + alot of supension work, i'll take a 400whp car that can hook and run 11s, thats still very streetable and most importantly, is N/A because you don't see any fast N/A newer stangs around here (fuel inejcted). Also, your crankshaft will need rebalancing probably, im not sure if im keeping my stock one, i think i will bore my engine a good bit its still in the air right now. As for your block... its the lighest and strongest 4.6L production block that was made.... no point in going anywhere else, its a Teksid, a company in italy who today still makes blocks for ferrari, now don't you feel cool that your car has a little ferrari in it? lol... well almost. oh the hp rating for your block is upwords of 1000whp so whoever told you 600...mmm idk.