03 Cobra Heads on 98 GT, worth it?

benjaminbeazy · Jul 4, 2009

Hey guys, I've been lurking for a little while but this is my first post (yay)! I know there are a lot of threads on here about PI swaps but I didn't find something entirely specific to my application and I'm really looking for some insight. I've got a stock 98 GT SOHC 5 speed @ 84k mi. Found a pair of DOHC heads out of an 03 Cobra complete w/cams and primary chain I can get for $850 or maybe 800.

I just picked this car up a month ago and all I've done so far is CAI (just for looks really). I've got 4.10s but I'm waiting on a new girdle so I don't blow my nice new gears out the arse. I'd like to turn this into 'vette-eater and just about everything I've read says the PI is pretty much a necessity. I might put a blower on it someday, but I don't wanna touch a bottle.

I've read that forged pistons are a must with similar swaps and I know there are many little odds and ends externally, but anything major I need to consider going to the DOHC? I'm sure I can dig up an intake and the little stuff on the cheap. Any other internals need changing here? I need a new computer too, don't I?

so yeah.... what do you guys think, is $800 worth it? Or should I be looking for 4v complete?

Thanks so much!

jeremy canter · Jul 4, 2009

you talking about a cobra swap>on a pi motor > it can be done > but think about this > my buddy has a 03 gt with long tube headers and a JLT cold air intake > he runs basiclly the same times as I do at the track (I have a 98 cobra ) it's no slower or faster than me and it really pulls great in the top end above 3500-to 6000 > I think you should take you $800 and keep saving > buy NEW heads from summit or ford racing and a nice trick flow or PI intake along with the install kit and install a good set of headers> you will be very happy with the out come > but you will get more BANG for your buck if you also get a tune > total cost to you low end $1200.00> high end $2500> and you car will make 300hp or better on your NON-PI bottom end because of the higher compression

benjaminbeazy · Jul 4, 2009

jeremy canter said:
you talking about a cobra swap>on a pi motor

forgive me if i misunderstood you but i don't have a pi motor, i've got the GT 2v SOHC, the heads i'm looking at are 4v DOHC, which is where my curiosity stems from...

seems like it'd be a little more involved than just a straight 2v swap but also should see even more power. i would basically end up with a terminator top end and a teksid block. it's pretty obvious i need to upgrade to some sort of pi head/cams etc. but is it a good idea and worth it to go to this 4v configuration?

BTW, i've also got a sniper delta forces tuner. haven't noticed much yet, but i'm sure it will come in handy in the near future..

Chucks98 · Jul 4, 2009

you will need more than just the 4v heads. you will also need the intake, throttle body, air inlet pipe, exhaust manifolds, and either the 4v COPs or something aftermarket for the plug wires. plus theres probably a whole lot more stuff im forgetting.

what are your long term power goals? unless you're looking for alot of power or ur just dead set on having a 4v, i would just build up the 2v.

with the npi shortblock, putting pi heads on will increase the comp ratio to approx 10.4- 10.5

and teksid blocks are found in 93-98 mark viii's and 96-98 cobras. 03-04 cobras have an iron block same with 96-04 gts

248a · Jul 5, 2009

you can't just swap 4v heads on a 2v bottom end. On top of all the little odds and ends you're going to need, the static compression would be too low. If you're dead set on a 4v, start with a 4v block, otherwise you're going to going to have to replace mostly everything short of the block, crank and connecting rods.

Like the others have said: Focus on building you 2v up. Or start saving.

03 Cobra Heads on 98 GT, worth it?

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