Can't decide between ported L92s vs PRCs 237!
 

My intention is to awake my stock LS2 a little bit, the plan is having a custom grind cam and a pair of good flowing heads with a LS3 intake, I'll be getting everything from Texas Speed so I was looking at their L92 CNC'ed heads which are a steal for $1300, but then I'm having a fear that I'm putting too much ponies on the table!, so shall bite the bullitt and get a pair of PRCs 237 instead for $1100 more? is it really worth it for a stock stroke engine?, I'm asking that because I've noticed that they have a VERY similar flow numbers (based on whats mentioned in TSP pages).

PRCs :
https://www.texas-speed.com/p-1171-p...der-heads.aspx

L92s :
https://www.texas-speed.com/p-1179-p...ted-heads.aspx

I'd personally use w/ TSP's 237 head out of those two. Toss in a ported FAST 102.

Our PRC 237cc heads made over 30 more hp on our engine dyno vs our ported LS3 heads. That being said, you would gain more running the PRC 227cc heads as the 237's and the LS3 heads will actually drop compression due to their larger chamber volume. The 227cc heads start out at 62cc and you can mill from there. You'll gain more from the bump in compression vs the extra airflow of the 237's.

Lonnie

Lonnie,
What size of a cam can you run without flycutting ? These TSP 227/237 are both 13.5* heads, right?

With the valve size of the 227 we can run up to our Magic Stick 4 camshaft (239/242) without flycutting. The 237 would kill some clearance due to the larger valve, unless he plans to build a larger motor the 227 would be favorable for sure.

Thanks
John J

Lonnie/John,
Would this same assesment be true for the PRC 237's vs ported 823's on a 13:1 416? Also how would it perform with the 237's at a 64cc combustion chamber size?

So what you are saying is having PRC 227s with stock LS2 intake is a better choice than going with PRC 237s with a LS3 intake?. Actually, the reason I want to go for a square port heads is because I already have a spare LS3 intake and I thought it would be a good idea to use it in my build.

What if I milled the LS3 heads to match the 10.9 CR?

The 2.165" diameter LS3 intake valve already compromised PTV clearance and can't afford further milling unless you're gonna run a 218 size intake lobe
And any time you can have similar flow through a smaller runner, that's a no brainer

The PRC 227's and PRC 237's are both Cathedral port heads. He is comparing both of these heads versus the 823 L92 CNC ported heads from PRC. With the smaller bore of the LS2 and using the large intake valve of the LS3 head you have to worry about valve shrouding and will hinder flow during combustion. That's why he says with the smaller port, smaller bore it is best to go with the smaller runner and smaller valve of the PRC 227's to better utilize intake volume velocity and flow numbers are still very comparable. If the original poster plans on going with a bigger cube motor later down the road that's where he would recommend buying the PRC 237's over the PRC 227's. I hope this clears up some confusion.

JayTS definitely has it right here. 227 and 237 are cathedral. The 237 was really designed for larger cube strokers like 402's and 408 motors. That runner size, valve size, and combustion chamber don't promote the low end power people would expect from a stock bottom end motor.

The LS3 heads have the same effect as the 237s would due to size. If you were to mill them down to gain the compression back you would kill a lot of piston to valve clearanc e preventing running a large camshaft.

JayTS, to answer your question I feel like its hard to compare because at that point the intake manifold becomes a serious question. If you put a good sheet metal manifold on top of the LS3 heads and try to rev it high I would expect a larger peak number due to more flow. With most street intakes I would lean towards the 237 because LS3 street intakes are bad, whether you talk about FAST or stock.
For that setup I would almost want to look at the 247 head we have. At that kind of compression, and assuming a good intake is on there the 247 would do better. We have a 14.5:1 416 solid roller motor with 247s and a ET 2 piece intake in one of our race cars right now, last engine dyno was 760+ so cathedral will definitely perform.

I totally got the idea now :thinker:

So to wrap it up, here is my plan :

PRC 227 heads
Fast 102 intake
Camshaft : 223/229 - .629/.629 @ 115+4
1-7/8 LT headers with no cats.
T56 M6 with 3.42 rears

I'm now ready to pull the trigger on this deal!

Texas Speed : Expect my call on next Monday morning.

Thanks for the quick and thorough reply,
To add on to my setup, it will be in a lightweight RX7 and intake manifold was limited at best being a Tony Mamo ported FAST 102/NW 102 to compliment the 64cc PRC 237's, Johnson 2116 Limited travel lifters, and a custom hydraulic roller BTR cam (243/262) and of course being a 417ci shortblock. If I was going to change I would go with the PRC small bore LS7 heads and a LLSR cam setup. Wish I would have gone with the 247's but I got a deal on the 237's. Thanks again!