Quote Originally Posted by dash View Post
some comments
projectzerog forum had a number of built DSM powered pickups, put truck oe 5speed & diffs to the test


a hi strung DSM/2.4....
There are a few factors in this we have to consider. While the 7 bolt 4G63 has the same static CR as the 4G64 in our trucks (8.5:1) the 1G is 7.8:1CR. So, naturally the 6 bolts will make less power per # of boost besides turning up timing to accommodate yhe lower CR numbers. Then we have overall displacement (bore, stroke, combustion chamber CC) mixed with cam specs (lift, dur, overlap), valve sizing/velocity. These trucks make 350whp consistently around 15psi on smaller turbos than I'm running. If we do the basic principle of 10hp per # of boost (of course this is relative and could be +/-) we should be around, should, 400whp @20psi+/-. Not to mention a lot of DSM guys run very low timing. When doing my setup I was constantly recommended nothing more than 12⁰-13⁰ total timing at 15psi, which is ridiculously low. Not sure why a lot of G63T guys do that, but there is no reason to be that low. I generally have 16⁰-18⁰ in my daily driving street tune total timing @15psi. There's a lot of HP loss when going to 12⁰.

Where was the block cracking? Cylinder walls? Besides deck height and some oiling designs I thought the G64 and G63 were pretty similar in design. I know the newer gen 4G64's than our trucks run are used often in hybrid builds, but they also use our truck blocks. I know the 4G63 2G block is good up to about 800 on a wet deck/unfilled block with sleeves. After that dry deck, filled, sleeves, and oringed block will put you way into the 1000+ margin until you start warping the deck surface some. I may look into sleeves if the cylinder walls were giving out.

The main reason I want to run a lighter flywheel is just a little quicker revs, and honestly the OE one is ridiculously heavy. It would probably be beneficial in a drift build though, due to the inertia energy helping out in transitions, but that's just wild guessing.

I'm using just some DNJ cast 0.020" pistons. I could probably push them farther (they've seen 25psi a few times due to original waste gate issues when I first was running on the piggyback), but I'm very hesitant to push cast pistons past the cylinder pressures of 400whp.