Sxynerd

Stop!!!!!!! Read it before you reply or I reserve the right to call you a retard! Answer the question I'm asking, please... I know all about cost of swaping and blah blah blah...

Will the heads off a 4v bolt right up to a 2v block? I heard differences about water passages, but I believe they are the same.

new topic question: Unrelated to the first question... I know this is where it gets tricky!

What will the CR be for a 99 2v short block with 96 4v heads?

importkiller89

i belive the block in the cobra and the gt are the same but im not 100%. n i belive that if the pistons r the same then the compresstion ratio should be what the cobra's is.

amoosenamedhank

I don't know this for sure but I just recall someone saying that there was some mod to the cooling system that you had to do for the swap. I thought it was droptoppony that said but I'm not sure. Try sending him a PM.

Personally I guess I would rather just have the entire engine. Already forged crank, aluminum block, plus you will have all the timing pieces already. Just seems a lot easier to me then trying to piece it all together.

oxfordgt

Since a 99 has 18.10cc pistons and I think 4v heads have a 54cc chamber I think the CR will be around 8.5:1. I'm no expert thats just my good guess.

Sxynerd

Now I'll share the rest of the story... A friend can get me a blown cobra motor for around 500 bucks. That includes all the acsersories and even the wiring harness. Since I wont know the extent of the blown 4v it would be nice to be able to swap around everything off one block to the other "if need be". My block only has 30k on it so I at least know my block is sound and can handle many more miles. And with a CR thats low, I might miss out on some low end Tq but with a SC I'll be able to run an IC and make my 400hp numbers I want "more efficiently" for a better all around driver.


Any one know the RWHP to a 4v with full bolt ons?

dsbsurfn

4V Heads from 96-98 have a 52 CC Chamber. 99-01 have a 54 CC Chamber.
Piston dish 2V 93-98 = 11CC
99-up = 17CC

Compression Ratio
52cc chamber + 11cc Dish = 9.17
52cc chamber + 17cc dish = 8.53

Data from How to Build Max-Performance 4.69-Liter For Engines by Sean Hyland.

Sxynerd

I don't know how to read this? I don't get the math how do I figure the final CR?

Edit:
Oh I get it! duh... Is there any real power loss lossing that much durring NA aplication? Also since lower compression is better for pump gas SC applications, wouldn't this be more benificial? For say 10-15lbs psi?

01Steed

You can take those Hyland numbers and throw them out the window. They're inaccurate at best. They're close, but if you're going to take the time and trouble to publish numbers, why not make them accurate?

'99-01 Cobra heads...51.2 cc +/- 0.5. '03+ = 53cc +/- 0.5.

2V 99-00 piston volume = 18 cc. 01+ = 15.8 cc.

So for you, c/r would be ~8.4:1, given all stock gaskets, etc.. Too low.