Patron

So correct. Here’s a oldie but goodie. Now Killer ask yourself is around 3k worth the small gains you could buy a vacuum pump which is always welcomed.

http://www.hotrod.com/articles/hrdp-...er-heads-test/


Called this build Easy $ as I have the same heads. Funniest thing is a Super Vic with the same build made 708fwhp and a smaller carb on YB.
* Figure What Darin told me that the CID is better used for 8k + or over 800hp Vs Holley High Ram 102 or Super Vic. Both are better to 7500 and in cost $500 for efi Vic. $1k for CID and EFI. Just things to think about.

https://ls1tech.com/forums/parts-cla...n-nitrous.html

Foxkiller

Thanks for all the relpies. I knew that there was slot of knowledgeable people on this site. I have read a lot post and I am doing my best to educate myself before taking the plunge. I had an old engine builder tell me one time to buy the best heads that you can afford. And that is what I am trying to do. I'm glad there are so many choices out there but for someone that doesn't build an engine everyday it can be a little confusing. I am leaning toward stock heads that have ported by total airflow or Frankenstein.

G Atsma

You are not only looking for air flow, but also flow VELOCITY. This is where smaller port volumes that still flow well come in. A good combo of a small port that flows like crazy will give you more flexibility and MUCH more power under the curve. That is why I like the TSP LS3 CNC port job. VERY good flow but thru a port with only about 8cc more capacity than stock. Very little grinding for a bunch more flow is what you are after.

Foxkiller

Which head would be best for a 408 ls?

Tuskyz28

Flow numbers don't mean

Remember flow benches are like dynos. One go be higher than the other one.. I've seen heads flow 360 cfm and others flow 340 cfm. On the same motor the head that flowed 340 cfm outperformed the higher flowing head at the track.

Do you plan on running a single plane intake?

Foxkiller

Agreed, flow numbers do vary. Yes, a single plane intake.

Tuskyz28

Well a single plane intake is go help a LS3 head big time. I would go that route for sure with a single plane intake. And don't be scared to turn some high rpm using LS3 heads and a single plane intake. Do some high compression as well. Might even want to consider a solid roller... Frankenstein Racing is who I recommend for a mean CNC port program.

All the guys running LS3 heads with no SUCCESS is running a dual plane intake, a cam that's not speced correctly or just not turning the combo up high enough in the rpm band.

Foxkiller

Thanks for the great info tuskyz28. I wish heads were measured by port volume instead of flow numbers. Flow numbers can be so misleading.

Tuskyz28

No problem brother.
A lot of companies flow they heads on a big bore motors then post flow numbers to make their product look good... which can be very deceiving. Some of these companies are a joke.

KCS

iTrader: (20)

The GMPP CNC program is notoriously crappy. I've heard from a few local shops here in Houston that claim they lost power over a STOCK set of LS3 heads...

Personally I think you'd be happy with the unported OEM LS3 heads. They'll get you 600hp pretty easily and leave room to grow later on down the road, plus they're much cheaper than the aftermarket alternatives.

Patron

Please do this if running a single plane! Gear the damn car Correctly with the Weight,rpm and trans being used.

Here you are let’s you see what duration does and intakes. Also how much more cam to get to 600hp. Ballparking it. A good cam grinder will have you on point. Found this build in 1 of my email folders marked as 440-383 factory Lq iron blocks. Also have this mag.


https://www.google.com/amp/www.hotro...-block-ls/amp/

Patron

Oh yea that’s from the EMC so no dyno tricks 550 ftlb’s of Tq can’t happen with Factory Ls3 heads you need aftermarket heads....LMAO!


TuskeyZ this is the one for u for your truck. all that Tq you wanted!

G Atsma

I agree. The stock LS3 head is grossly underappreciated.
The GMPP program hogs out way too much material, which I think stalls the flow. As I have said, there are heads out there flowing much more with SMALLER ports. More flow with more velocity will get you power every time.
I think if porters would work on the exhaust port ONLY and leave the intake alone, would be best on the LS3. But that's just me...

Patron

Your right G Atsma as well as KCS. It’s not a perfect world you can make it work still. Most smaller ports come in around 264 to 270 as far as intake runners on CC’s. Darts come as Cast in 280 form. You’d lose some Tq with the GM Cnc program but not enough to buy another set. Good valve job and maybe some blending would help. But as Is it can and will make anything he needs even past 700.

G Atsma

Foxkiller- Your mechanic might think the GMPP heads are the real deal, but must not know what else is out there. Do your own looking around, buy the heads YOU think will do the job for YOUR situation, and go from there. As said, the stock LS3 heads have a LOT of capability, being able to support more than 600 HP. If you need more, the head porters we have mentioned will get the power out of the heads. GMPP will not, nearly as effectively.

99 Black Bird T/A

iTrader: (4)

Having picked out LS3 heads for my 99TA a few months ago, I too would pass on the GMPP LS3 CNC'd heads just like the others said.

SPS Haymakers might be worth mentioning and checking out. These were on my list but the turn time was going to be slow as they were waiting on cores fr the foundry when I talked with Gavin a few months ago.

I think Reher-Morrison's LS3 heads worth considering. Darin raises the roof of the intake port a hair and some other cool stuff. Call Reher-Morrison they are very helpful. These are the ones I selected.

​​​​​​There are a lot of good choices in ported LS3 heads to get that 10-25hp, but as mentioned the stock heads are very good.

Patron

Oh he doesn’t have GMPP heads but thinking about them My Mistake. Refer to above post. All will be in the same ballpark. Your choice in porters. I’ve used FRH and D. Morgan no complaints got exactly what I asked and paid for. Ever ones got a program now. Thing is Ls3 heads don’t go for what they use to bare @ $175ea bare. Now like what $300 each Bare? If you get the casting cheap a typical Cnc program goes for $900 to $1200. BES has programs as well as AI,WCCH,TEA, Slick Rick...etc.

I think I came in around $1500 at $175 each bare with FRH porting $1100

G Atsma

TSP will port YOUR LS3/L92 heads for $750 plus valves and springs, or $1300 outright (no core) with stock valves, springs additional. This is just an example, not specifically pushing TSP.

Patron

That’s the Deal of the Day... LOL! But truly is about the best deal you’ll find. Cause you got to find or have a pair to send to your choice in porter or Bump in price. They will as stated be in the same range + or -. Cam/intake choice with compression will make more difference than different programs just maximize the flow under the curve with cam choice and pick your RPM to mate with the choice in intake. Any listed porters programs with Ls3 heads will do more than you ask.

G Atsma

I mean, if you get a decent pair of junkyard heads for a couple hundred bucks, then send them off to get ported, it is essentially a full rebuild/recondition PLUS porting for the price. I don't know about y'all, but to me that IS a good deal!