Boosted One

iTrader: (6)

I'm looking for some insight to help me make a decision. I'm a going to build a twin turbo setup for the Nova and I'm looking for 650 to 700 rwhp. In the car now I have a 98' 5.7 with eagle H-beam rods and Mahle -2cc flat tops, heads are Cartek 3x ls6 milled with 11.3-1 compression, Cam is 230/236 598/610 on 113 if I remeber correct. I got the heads and cam from forum member Big Mike a few years back. Anyway, I also have an 07' 6.0 lq4 that I recently picked up from a junk yard. Motor has 3k miles on it!

So I have a choice. I can replace the heads on my motor with 317's and add the turbo's to it. Or I can sell my motor for ~5k and build up the 6.0. Either way I look at it I'm tearing into a low mileage motor

Is there anything I should know about the 1998 block that would make it a bad canidate for those power levels? I do have good rod bolts in it, but stock main bolts. Computer is a 98 too, but I do have an 03 computer and harness that I got with the 6.0.

Thanks for any input.
Frank

93formto98T/A

iTrader: (28)

The only benefit I see is the lower compression ratio of the LQ9. The CR in your 346 is pretty high and 317 heads alone probably won't bring it down enough for 700rwhp on pump. I can't remember if it was just the 98 heads that were weaker or 98 block and heads that are weak. At 700rwhp the alum block won't even break a sweat so strength wise you're fine. My old setup was 8.5cr and 17lbs on pumpgas=740rwhp. I ran a 364ci 6.0L w/317 heads but either block would have worked just fine.

transamfreak01

iTrader: (8)

im not 100% sure but for some reason i thought i heard it was the heads.
and yes the alum will have no problem at that level.

i would shoot anywhere from 8:5 to 8:9cr. at those levels youll be able to boost more with pump. i would go with the 6.0l but i think both will be fine. they have both shown to make crazy power. also i was wondering if you could pm me how much you got that block for from the yard and if it was a short block or long block b/c im looking to pick one up late summer. good luck though

themachasy

iTrader: (5)

See what you can push, you should be able to get close to that number depending on the turbo and boost pressure. High compression and turbos work pretty well together as long as your tune is good, and you can always put some water meth on it for a bit more boost without issues. Try it with the 347, you shouldn't have an issue. If its not to your liking, swap. But I don't think theres much reason to change from a built motor.

Boosted One

iTrader: (6)

hmm. It's looking like if I swap out my ls6 head for some 317s, it would put me around 9.4-1.

Frank

Photochop

iTrader: (74)

I was in the same boat as you basically when I started my build. I had a forged 347 that came in the car, a nice set of TEA ported 853s with 2.02 intake valves (not the best casting, but nice for what they were) and a set of Mahle -2cc flattops. The compression was around 10.5:1. I felt that a little high for boost - as I wanted to run pump gas and no meth. I sold the TEAs in favor of some stock 317s that I had cleaned up, a valvejob done on them, and had a new PRC spring kit installed. This netted me 9.3:1 compression, which is what yours will be too with 317s and -2cc mahle flattops. I'm currently having my car tuned on 13psi with not much timing (tuner has been experimenting with boost from 10-13psi and timing at 12-17 degrees) on 91 octane pump gas with my 76mm turbo. The previous owner had an 8.8:1 365" motor seeing 14psi on 93 octane and was able to have more timing - 17*. You'll make more power with more boost and timing with a little less compression. BUT out of boost, the motor will feel more responsive with the higher compression. If you can run more octane and are able to bump up the timing some with the higher compression, power should be comparable (ie, run meth or a higher octane mix).

sultan(ZR-1)KSA

in my opnion , the 4inch bore is a better choice due to having a huge selection of rely hi flwoing heads in the market

Boosted One

iTrader: (6)

Thanks for the feedback guys! Looks like I have alot of things to consider.