Block differences

[Fang99]

Block differences Can someone tell me what the differences in the short block are between a SOHC 4.6 and the Cobra(DOHC) blocks. Compression ratios, rods, pistons, crank, etc.?

 

[Hissmann]

Well, if you just want to know the difference in the SOHC and the DOHC Block here you go. If you want info on the whole engine let me know. They are from a different casting. The DOHC is aluminum and the SOHC is Iron. The 96-98 Cobra block is considered by most to be the stongest and is preffered by most racers wanting to push the limets. Both SOHC and DOHC heads are interchangable with each other (you can use on either block), but you must use the intake intended for the heads. 99-present heads flow better than 96-98 heads, but the power gains are neglegable. the SOHC has a cast Iron crank that is good to about 500hp, and the DOHC Cobra has a Forged steel crank that some have taken to 1500hp. If you need more let me know.

 

[Fang99]

Thanks for the info, Hissman. This is what I am planning on doing, so see what you think. I have a 99 Cobra with only 16,000 miles, but no warranty, I am the second owner. The problem is that I have a "spun" bearing. What I would like to do while the motor is out is replace the factory internals with a stroker kit from Modmax, CHP, whichever I choose. Do you have any idea about the powergains I may see on a n/a motor? Anyone?

 

[Hissmann]

If you are going to stroke you might as well "bore" it is easy on these blocks, all you have to do is change the cylender sleeves out for thinner ones. Sean Hyland carries these. That will take you to 5.2 liters safely. But if you just stroke it will take you close to that depending on what kit you get. 5.0 liters is what most people go to. What compression ratio are you thinking about going with. bumping up to 10.0:1 will give you about 10-15 more ponies depending on a few other things. With the 5.0 liter stroke you will probably go up about 30 hp and 40-45 trq. Once again this depends on a few other things. Going to a 5.2 will get you a few more ponies and about 10-15 more in torque over the 5.0, usually. You might want to also think about cams. Go with a stage 2 (NA) from Sean Hyland. This will give you a lot more durration and really help those nice stock heads you've got breathe. The cams will get you a few more ponies again, but you will really notice a huge jump in torque accross the board.

 

[Hissmann]

oh yeah, my numbers are to the wheels.