5.3 or 5.7 heads

Guys, looking for your input on whether to go with 5.7 stage II heads or 5.3 stage II heads from Absolute. Flow #'s are darn near the same. Compression would stay around 10.1-10.5 on the 5.7s, and on the 5.3s up to 11.0-11.5.

The cam will be about a 224/224 586/586 114, subject to some minor changes.

Should I take advantage of the higher CR of the 5.3s? Little bit more costly, but that's not an issue really. Or stay with 5.7s? Guessing the extra compression might make another 5-10 rwhp, but is that worth it?

Opinions please - especially if you've been down this road. Love to decide soon.

Are you going to stay NA ??

I'm strongly leaning towards the 5.3s. They seem to have awesome flow characteristics (as good as the 5.7s), better swirl, and a higher CR. Should make good power.

Love to hear some suggestions though.

Well if I was sure to stay NA I would get as close to 11.5:1 comp as possible. . .

I missed your first post TB - posted at the same time.

MA - for now. I figure low 400's should make me have, and pass emisisons easily. Enuff to get me kicked off the track.

if you still plan on going with boost then go with the 5.7's

I think I'm going to stay NA for a bit.

Well if I was sure to stay NA I would get as close to 11.5:1 comp as possible. . .


Chris,

I got 11:1 CC. It's sweet except you can only put 94 octane, which means trips to the states become difficult. As well you are limited to going NA or nitrous. I'm starting to like the idea of Nitrous because, you have the power when you wnat it. Sometimes it's nice having just enough compared to more than enough;). Nevertheless, Personally I would go with the 5.3 and squeeze out as much NA as possible. Then hit the bottle :D

ChriSS....I would wait on more results from the new AFRs myself. With that cam Tonys car put down 480rwhp. :bow:

if you want to run big boost or nitrous later on on a built motor, wait for the AFR 225s.

If sticking N/A now or with a big cube motor, think about the 5.3s or the AFR 205s

If you want to run boost on your stock motor, go for the 5.7s.

thats what I would consider.

Darren/Craig,

I've thought about the AFRs and there is a lot of hype about their coming. Also, Patriot and Absolute are also looking at doing more improvements, but considering how small of a cam I am considering, that much more flow isn't really going to make a big difference (I think) for the money. The AFRs are very pricey, and for all I know, they'll prove to be only marginally better than the Absolutes. But they sound promising, I'll admit that, but the gain of 10-15 hp for the extra $2000 CDN doesn't make sense to me.

AS heads are well priced and with a big cam are hitting 460 rwhp (I'm staying much smaller). AFRs will cost me nearly the cost of a blower (more than half), and I think I've decided to spend my money on a home and other things for now.

I could wait, but naaaaaahh! I'm impatient. :D

At least that's my logic. :think:

LOL ChriSS, I hear you with the patience thing...its taking everything I have NOT to go on another spending spree.....I need more power now!!!

I think its the design of the AFRs that will make them better then the rest. I see what your saying for sure. The 205s fully dressed for 2200usd as opposed to what your looking at is quite a price differance.

But, just to mess with your head a little more, McRats car put down 465 untuned with a 224/228 cam....

I've thought about the AFRs and there is a lot of hype about their coming. Also, Patriot and Absolute are also looking at doing more improvements, but considering how small of a cam I am considering, that much more flow isn't really going to make a big difference (I think) for the money. The AFRs are very pricey, and for all I know, they'll prove to be only marginally better than the Absolutes.

Yeah there not cheap but the AFR's interest me the most due to there smaller faster flowing ports which are supposed to give you much more power across the board with less of a cam . . . so they were claiming anyways. Makes sence when you think how much they have to hog out the oem ports to makem work . . . either way im sure you'll be hauling ass .

Dave, can you hear that? :eek: I think I hear 205s calling your name. :cool:

But, just to mess with your head a little more, McRats car put down 465 untuned with a 224/228 cam....

Those are killer numbers! Ah, the lure of temptation.

Dave, can you hear that? :eek: I think I hear 205s calling your name. :cool:

A custom built 427 C5R style block with lite weight strengthened internals is calling my name. :p

Im going to leave the transam as is and start getting ready for the LS7 blocks to start shipping *drool* . . . .plus ill need a little donor targa top vette to stuff it in :cool:

I know the AFRs will be good, but you have to consider how they are getting great numbers right now. All the tests I've seen are with modified 2002 Z06s that are starting out at 385-395 rwhp. They are great numbers at 440-450, but those cars are starting with 40-50 rwhp more than me.

I'll admit that the AFRs will likely give another 10 rwhp for the same cam over Absolutes, but not for another $1200-1500.

Just a thought but that gfx3 cam you were looking at a while back would get you there without heads and mucho change in your pocket for hookers and blow . . . . or whatever floats your boat ?

Lou G loves the AS heads, but I don't think any of his cams will pass emissions.

I'm talking to Allan Futral currently.

By the way, I've ordered the S2 5.3 heads with comp 978 duals, titanium retainers, etc.. Now I just got to decide on the cam specs, and get some chromoly pushrods.

Then I shall be replacing the tr55 plugs with some colder tr6s, I think. I'm going with just a basic LS6 oil pump and I might do a little home porting on it myself. Probably keep my stock timing chain.

Really shooting for 410 rwhp unlocked with the set up. But I'll live with a wee-bit less if needed.

You should get an ls6 intake while your at it and you will easily see 400rwhp. I would replace the timing chain too. Its a cheap buy and something that should be done while everything is apart.

Congrats on the new purchases Chriss, 400 plus to the ground will be sweet.:cool:

You should get an ls6 intake while your at it..

Congrats on the new purchases Chriss, 400 plus to the ground will be sweet.:cool:

Already done Kaos.

I may get the timing chain. Just a GM one for $40. Nothing special, but you are right. Small expense for a part the WILL eventually wear out... easier to replace now than later.

Already done Kaos.

I may get the timing chain. Just a GM one for $40. Nothing special, but you are right. Small expense for a part the WILL eventually wear out... easier to replace now than later.

Its only 30$ more for a nice double roller through scoggin dickey . . . might as well upgrade if your going to swap it. Thats the worst part of the job ( the oil pickup tube ) :yuck: