laytoncamaroz28

iTrader: (10)

i gotta 98 z28 m6 with strange 12 bolt and 4.10 gears. im rebuilding the engine am curious as to what cam to use with my gmpp ls6 heads. the specs on the heads are 62 cc combustion chambers, 85 cc exhaust runners, 250 cc intake runners, and flow about 300 cfm at .600 lift. im gonna run the ls6 intake and 42 lb fast injectors. the shortblock contains of stock crank, manly forged i beam rods, and cp forged pistons with valve reliefs. i have a 228r cam in it now and LOVE it. i was thinking reuse this cam but would also thinking going bigger. this car will have to be my DD for a few more months. thanks for any info

hammertime

iTrader: (1)

JMO, but 250cc is a huge head for 346ci. There are several choices in the 205 to 220cc range that offer similar peak numbers.

If this is your daily driver, those heads will make for a lazy setup in any part throttle operation. You might consider running your stock heads until you have another DD lined up, then run the GMPP LS6 heads along with a custom cam spec'd by one of the reputable vendors here once you don't have to deal with the daily grind.

laytoncamaroz28

iTrader: (10)

well i got em for a really good deal so im putting em on. hopefully they dont disappoint me.

garygnu

talk to Patrick-G .did you have the heads flowed and have sheets?flow the heads and talk to Patrick-G.

1sick-Z

iTrader: (3)

I ran a similar setup. 346, Dart 250cc heads,ported FAST 92. I cannot speak for the 250cc ls6 heads but everybody I talked to and everyshop told me that 250cc heads will ruin my car it wont make any power. Hell many told me that the heads would not even work on a 346 with 2.08 valves. Dart told me to call FMS Alan was even iffy about the heads. He still made me a cam though (high 230s)and my car ended up making over 480whp once I finally got it tuned right and the bugs worked out of it. With 10 bolt and t56 of course but regardless it runs really hard.

My point is the big heads despite what everybody will say may end up working well. I lost a little bit of bottom end but after 4500 its a complete animal.

You are on forged rods. I would buy some LS7 lifters and plan to rev up. You also have power on the table if you ever want to go bigger cubes I could see those heads working really really well. I also beleive that the GMPP heads you have are set up for a 3.90"bore. I would run them and see what happens. Just get the right camshaft/intake and you will be fine.

PM me how it goes.

hammertime

iTrader: (1)

No doubt that the heads can work, but to be fair, you confirmed that the bottom end went soft in favor of power in the upper range. As long as the OP is ok with that in his daily driver (for a little while) then I'm sure he'll manage.

Patrick G

iTrader: (14)

You'll need to err on the smaller side of the intake duration to keep the low and mid rpm power decent, but you'll want plenty of overlap to make good power (8-10 degrees at .050). I would recommend something like a 226/230 .597/.600 110LSA +1 advance cam ground with EPS lobes.

As you can see, this is fairly close to your 228 cam, but the valve events are better suited to the flow of your heads. Lobes will make more power too.

laytoncamaroz28

iTrader: (10)

thanks for all the replys guys. sickz at what rpm did your set up make max hp? and torque?

laytoncamaroz28

iTrader: (10)

anbody else?

studderin

iTrader: (28)

what size in the intake valve?

laytoncamaroz28

iTrader: (10)

2.00 intake, 1.55 exhaust

1sick-Z

iTrader: (3)

6900 is max, I rev it to 7200. As for the tq it is just slightly under 400 rw @ 4500.