KB99WS6

iTrader: (6)

Wondering if the heads below will work on my car (stock 01 Z06) along with a 228R cam (228/228 .588/.588).

This is all it says in the ad:


Edit - i wouldn't be using those springs btw, I already have dual golds

KB99WS6

iTrader: (6)

Can anyone help me?

I don't know that much about heads technically, but I assumed the valves were too big for stock cubes. However I sent a message to the seller which I believe is keith craft themselves (very respectable shop more known in the mustang world) and asked if these heads would work on my stock 01 Z06 with a 228r cam and got this response:

..But again, arent the valves too big?

UGotBeaT

ud be better off buying them some else where...jmo 2.080 valve is to big for a stock cube motor and 310 with that size valve is pretty bad you can achieve that with a 2 inch valve.

KB99WS6

iTrader: (6)

Yeah it's strange because I always remember Keith Craft having a great reputation and they also have 100% feedback on this auction site. But it seems they are responding to me with bad info just to try and sell the heads. They caught my eye though because they are only $1199 with free shipping and you can even get them cheaper because they are accepting offers too.

PREDATOR-Z

yoo much valve for those cubes and cam. Go with a head that floes ~300 cfm area and that has 2.02 or 2.04 intake with a small runner like 220cc or so.
Idealy a 5.3L head fully ported like TSP stage 2.5 or similar.

KB99WS6

iTrader: (6)

The 5.3 heads would be better than the LS6 stage 2.5's? Also, what cc would be best?

PREDATOR-Z

61cc heads for 11.1 compression and 8.47 dcr. stock gaskets

KB99WS6

iTrader: (6)

Thanks man. So you you think I'd be better off with the 5.3's with those specs over the LS6's?

PREDATOR-Z

Yes.... on that cam

KB99WS6

iTrader: (6)

How about these:

http://www.texas-speed.com/shop/item...id=84&catid=20

Don't know if they are 61cc though..

PREDATOR-Z

Yes these are the ones, just tell TSP to mill for 61cc chamber.

KMS.1320

iTrader: (1)

a 243 head should always perform better than a 5.3 head. It's just a much better port. If you are in need of compression, mill.

PREDATOR-Z

Not true in all applications.
In this particular 228R application the 5.3L will have better throttle response (smaller cc runner and thus better velocity), You would have to mill the 243s a bit more, reducing PTVC a bit, the 243s are more $$.
(unless the 243 CNC program is for small cc runners, like Livernois, but stage 3s are over 1500$)
Basicaly the 5.3L will have better below curve power at a better price..

KB99WS6

iTrader: (6)

And the PRC 5.3 stg 2.5's will have a significant power gain over my stock LS6 heads with that cam...both peak and under the curve?

PREDATOR-Z

They should add at least 30>35 rwhp.

I take it this is for a Z06? the black one in your avatar?

If so, and if it was my car, this is what I would do. Being a Z06 and the 243s having lighter valves I would keep those. I would send them to Livernois Motorsport and get them CNC'd (ported) with Comp or Pac single beehive springs, and milled to 61cc with a new valve job..
Livernois has 220cc 243 CNC program for these heads.

You allready have good heads to start with, that would just optimize them.
Otherwise bang for buck, the 5.3L PRC stage 2.5 would be my second choice.

KB99WS6

iTrader: (6)

Yes it is a black Z06. Here's the deal, my car is @ the shop now with the engine out getting pistons replaced under warranty so I am taking advantage to put in a cam and clutch (among other things) while everything was out as there will be no extra labor. Now I am thinking might as well do heads too.

So I already bought a cam kit; the 228r kit which already has the PRC dual springs, retainers etc. So in buying heads I won't need that with the heads. Not sure what type of price reduction I can get on the heads without the springs etc @ Livernois. As far as sending them to Livernois to have my heads ported, I don't think it works that way which I wouldn't have time for anyhow as I can't keep the shop waiting for ever. If I were to order there heads they just send me a set already done and than you have the option to send yours back in to them afterward and they give you $300 back.

As far as which of their heads to go with, on the auction site they show Stage 1 or stage 2 LS6 heads. From their description it actually seems like they are the same heads...they show the same 220cc intake runner and same 2.00/1.550 valves and advertise the same flow rates of 305 & 235, but the stage 2's have better springs.

...But it seems the flow rates are actually not as good as the PRC 5.3 stg 2.5's. So would I make less power?...Seems I'd have to go to their stage 3 heads which are $1799...and still advertise less flow rate than the PRC 5.3's. Hmmm...

Don't know what to do...

What are the advantages of the lighter valves by the way? Also when you said 30-35rwhp gain, you mean over my stock LS6 heads, or would that be over LS1 heads?

PREDATOR-Z

Over LS6 heads.
BTW, do not trade in your 243s, they are worth much more than 300$
I see your dilema, then I would just go for the PRC 5.3L stage 2.5 milled to 61cc. You probably could get those in less than 5 days.

KMS.1320

iTrader: (1)

a smaller cc runner does not always mean higher velocity.

ls2 bait

iTrader: (11)

dude you are really over thinking this. for that small of a cam you dont need huge flow numbers. not to mention you are only looking at .600 numbers which really dont do jack **** for you as your cam isnt .600 lift and im assuming you are still using an ls6 intake which really isnt the best intake for higher lift cams. just get the 5.3's and call it a day.

KB99WS6

iTrader: (6)

I don't mean to be over-thinking it, I am just trying to make a good decision. It's a lot of money I am spending here on everything and I want to do it right. And I am not just looking at the flow numbers @.600, I am looking at all of the flow #'s at different lifts. Yes, I also look at the .600 too just to see whats its capable of but I know the 228R is only a .588 lift cam. And yeah I still have my stock LS6 intake. Not sure what you mean by pointing out that my stock intake is not good for higher lift cams...what relevance does that have to me when I am not getting a "higher lift" cam? I've already purchased the 228R and now looking for the best heads for them, thats all. And for the record, I'd personally call a 228R a mid-sized cam. But thats relative to "streetable" cams, as my car is a street car, not a track rig.