-Q-

iTrader: (10)

Alright here's my situation...I've got a LQ4 short block that I'm going to build to go in my WS6. The only components that are set in stone right now are the short block and the LS6 intake with a Shaner S3 throttle body. I've been searching, reading, and debating until my head hurts about a head and cam combo for this motor.

I know when it comes to a cam selection, most of you would say to decide on heads, pick out (or have spec'd) a cam, measure PTV, and roll...flycut if you need to. Problem is, I live in Alaska, and apparently none of the machine shops here can flycut my pistons. I'm not making this up...I called the two most reputable ones in town today.

So I'm in a dilema. I'm having PatrickG spec me a cam out, and if I go with a set of 59cc ported PRC 5.3 heads, I can only go up to about .230 on the intake duration on a 110 ICL. 59cc heads with a stock gasket on a LQ4 makes just under 11:1 compression, which is what I was shooting for when I was hoping to run a larger cam. If I drop down to a 62cc or 64cc head, I'll have more room for a larger cam, but I'll be closer to 10.5:1 comp with the 62cc and 10.25:1 with the 64cc head.

So long story a little bit shorter, should I shoot for a larger cam with heads that yield .5-.75 less compression, or should I go for the smaller cam with closer to 11:1 compression. My goals were for 425+hp, but the hp number really isn't that big of a deal...really wanted to focus on building as much torque as possible.

Opinions, please.

blackmagicturbo

iTrader: (2)

you probably need more horsepower with a 6spd and 4.10s tho ?.. not torque , what does the combustion chamber have to do with cam size , just wondering?

-Q-

iTrader: (10)

Not a daily driver, but I do want sane driveability. I wasn't shooting for a Trex or anything like that to begin with, but something along the lines of a MS3, G5x4, etc. Car will be tracked occasionally, but will be driven more in a blend of city/highway driving.

batboy

iTrader: (6)

I would go with a little less compression ratio and a bit more cam. What's a 1/2 point of CR worth? Maybe 5 hp? A bigger cam will gain you a lot more power.

blackmagicturbo

iTrader: (2)

what about an ms3 and 5.3 heads ?

-Q-

iTrader: (10)

It won't clear unless you get the heads set up with recessed valves from TSP. I called them today, and they're about 3 weeks out from shipping. In another month, my summer will be almost over up here, and I'd rather not wait that long if I can avoid it.

-Q-

iTrader: (10)

The farther down you mill the heads (which makes the combustion chamber smaller), the closer your valves get to the pistons. A large duration camshaft can cause piston-to-valve issues with a small chamber.

outkast6991

iTrader: (34)

why don't you flycut yourself and have the best of both worlds?

batboy

iTrader: (6)

-Q-

iTrader: (10)

Whats up with the rolleyes? If you don't believe me, thats fine. I called Alaska Drag Bike and also Midtown Machine today...ADB told me they couldn't possibly flycut a piston with it still in the block, and MM told me they didn't have the tools to do such a thing. Those are the only two machine shops I know of in town, and certainly the only ones that would come recommended by anyone up here...

I don't know if you're rolling eyes at me, or rolling eyes at the fact that Alaska sucks.

batboy

iTrader: (6)

This was why I rolled my eyes, because people can't read.

-Q-

iTrader: (10)

My bad.

SOMbitch

iTrader: (8)

That is the best answer but honestly I didn.t do it either because it is a PIA. I guess it boils down to how much do you want it..

I would go with a smaller cam that will have a good DCR and make broader power losing only a bit up top.... You prolly will be faster but I gaurantee it will be a more fun streetcar....

outkast6991

iTrader: (34)

actually i read that no local machine shops would do it which is why i suggested he do it himself. it not exactly rocket science, if you can use feeler guages it's not that bad. if the op wants a big cam and compression it's smart to do it right the first time. either that or buy an off the shelf combo and flip a coin on your clearances.

-Q-

iTrader: (10)

I can't say I'd be very comfortable flycutting my own pistons...but I guess I haven't really considered it...

garygnu

whats the availability of 92 octane in you town?.how are you tuning it?I would go for the smaller cam set up.

tittan1500

iTrader: (8)

I went the high comp mid size cam route.... I have milled PRC 5/3 heads and a Torquer V2. I had to fly cut big time and I wish I would have went with a bigger cam! I can fit a cam that is any bigger so I need new heads if i want more lope

blkm6formula

iTrader: (2)

the smaller cam with more compression will provide a much better street car.

blackmagicturbo

iTrader: (2)

agreed ..

blackmagicturbo

iTrader: (2)

5.3s have a narrower deck hieght than a 241 ,243? i thought the combustions were just smaller in shape ?...