bigfatls6

iTrader: (34)

I am trying to find some one that has some horse power numbers with a comp xr281 cam in a bolt on car with stock ported heads.

jbwhite

I don't know if you are locked into the XR vs XER, but using bolt-ons and AFR heads mine put down 424.7 hp at the rear wheels. My heads likely flow better than stock ported heads, but this should give you at least a rough idea. (If you haven't already ported the heads, you may want to check out some aftermarket heads. By the time you pay for porting they aren't much more and generally flow better). If you go with the XER bear in mind it kicks in around 2500 rpm, so you'll need a pretty stiff gear (I'm running a 4.10). It will idle down to 800 rpm, but still not sure I'd use it as a daily driver. It would probably help if you went with the 114 LSA (I'm using 112). It just depends on how you use the car and what you can live with.

bigfatls6

iTrader: (34)

These are the spec on the cam i am pretty sure it jus tthe xr281. 228/230 .571/.573 on a 112lsa. The head are already ported and the engine is a forged 347 with about 12:1 compression. I will also be running a fast 78mm intake.

GuitsBoy

iTrader: (4)

Thats a pretty tame cam. Id put that in the 420 - 430 HP range depending on how well the heads are ported. The compression may be too much for pump gas with that small a cam. Run the numbers and see what you get for DCR.

slow trap

iTrader: (22)

with a 228r on a 112+2 i ran 11:7 scr and dcr was close to 9:0 if i remember corectly. it ran on 93 without issues but 12:0 scr may be pushing it. are you sure about the 12:0 ? my heads were 57cc with stock gaskets and no reliefs in pistons.

bigfatls6

iTrader: (34)

I was told it make 12:1 compression by the guy i am buying the motor from. He also said he runs 93 in it with out any problem. He said you can run 87 in it but you can't run it hard at all or it will ping. I think he only runs like 19 degrees of timing in it though also.

GuitsBoy

iTrader: (4)

Hearing this makes me cringe...

bigfatls6

iTrader: (34)

I have a 69 nova that has arround 12.5:1 compression in a 540. I can run 93 octane in it to street drive it I just pull a little timing out usually about 4-6 degrees. Thats a little different than a fuel injected ls1 though. I will definetly be checking how far down in the cylinder the piston sits when I pull the heads and have a valve job done. You guys might be right it may be less compression. I am hoping so I want it as streetable as possible. In the future if it does have 12:1 compression I might go to a different cc combustion chamber on the head.

AU N EGL

I run a comp cam 224/224 .581/.581 112 XER on LS6 243 heads. Not ported but were polished, ruff edges smoothed out. TPIS 78pp TB ( 2003 LS6 block )

My own direct CAI, TPIS LTs, Random Tech high flow cats and X-pipe, with open or straight pipes. 3qt accu-sump and oil cooler.

MN6 with trans cooler and 3.42s

Just over 400 rwhp and 400 rwtq

car weights 3325 with 200 lbs of me and 1/4 tank of fuel

GuitsBoy

iTrader: (4)

Apples and oranges. For one thing its a different animal than teh LSx architecture, like you already stated. But the big difference is that its a BIG motor. Big cubes invariably run fairly big cams, which of course have TONS of overlap. This overlap bleeds off compression and results in a lower DCR. The dynamic compression is what makes teh car drivable on pump gas, even though it has a high static compression.

redtail2426

iTrader: (10)

check my sig,thats the cam i have on a 112 lsa

Gary Z

JB, considering your mods and the manual transmission, 425 whp seems low. Do you have enough fuel? What is your AFR?

bigfatls6

iTrader: (34)

i am with gary z the 347 I have with the stock ported heads put down a little over 400 with a nitrous cam.