CNC'd L92s worth the $$$?
Thread Starter
On The Tree
Joined: Mar 2008
Posts: 135
Likes: 2
From: Austin, Texas
CNC'd L92s worth the $$$? If I were going to run a stock 6.0L or LS2 short block, very healthy cam, 1 3/4 Hooker Long Tubes, T56, etc. in a 1st Gen F-Body... Would it be worth it to go with CNC'd L92s over the as cast heads? What kind of power might I see over the untouched heads?
I'm thinking CNC'd so I could swap a stroker short block & bigger cam later on and make more power but I'm wondering what difference it would make with the stock short block. I understand the main issue on the L92s is the exhaust port, is the money to buy CNC'd heads even worth it or should I pay to have just the exhaust ported? SDPC has the CNC'd L92s with springs to
.650 for $799 a pop.
Also how hard can you push a stock short block? This will be a street motor but it's going to be leaned on. Should I change to ARP rod bolts on any swap or will the stock bolts be ok?
All thoughts are appreciated.
I'm thinking CNC'd so I could swap a stroker short block & bigger cam later on and make more power but I'm wondering what difference it would make with the stock short block. I understand the main issue on the L92s is the exhaust port, is the money to buy CNC'd heads even worth it or should I pay to have just the exhaust ported? SDPC has the CNC'd L92s with springs to
.650 for $799 a pop.
Also how hard can you push a stock short block? This will be a street motor but it's going to be leaned on. Should I change to ARP rod bolts on any swap or will the stock bolts be ok?
All thoughts are appreciated.
The stock short blocks are good to 500 hp maybe 700. The rods and then the pistons are the weakest parts. The cranks have been run up to a 1000.
I'm not sure on the heads.
I had mine hand ported and flowed at a cost of 1500. The exhaust picked up a lot when finished.
Does SDPC do their own or are they cnc'ed from GM. I had a set of the GMPP 243's that were cnc'ed from GM. They flowed ok but were designed for road racing. They developed pin holes in the throat area after several years of abuse.
I'm not sure on the heads.
I had mine hand ported and flowed at a cost of 1500. The exhaust picked up a lot when finished.
Does SDPC do their own or are they cnc'ed from GM. I had a set of the GMPP 243's that were cnc'ed from GM. They flowed ok but were designed for road racing. They developed pin holes in the throat area after several years of abuse.
Launching!
Joined: Nov 2010
Posts: 251
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I've seen the CNCed heads produce more power all over, and I've seen them lose power 
Its hard to say but it seems typical to pick up 15-25hp depending on your engine size and cam.
NOTE: Just because the SPDC springs say they are good to .650" lift just means it wont bind with lift under that spec.
You need to find out what spring RATE is required for your cam. If you dont have enough seat/open pressures your valve will float around. That last thing you need is to waste money on springs that wont suffice.
Its hard to say but it seems typical to pick up 15-25hp depending on your engine size and cam.
NOTE: Just because the SPDC springs say they are good to .650" lift just means it wont bind with lift under that spec.
You need to find out what spring RATE is required for your cam. If you dont have enough seat/open pressures your valve will float around. That last thing you need is to waste money on springs that wont suffice.
Thread Starter
On The Tree
Joined: Mar 2008
Posts: 135
Likes: 2
From: Austin, Texas
1LE,
Not sure but it seems they are doing in it in-house. Here is the link to the listing, doesn't really give a whole lot of info, guess you'd have to call and talk to someone.
http://sdparts.com/category/cylinder-heads-0?page=1
I definitely want these heads to last and if the CNC risks them taking a dump in a couple of years, I'd pass.
I agree with the springs. I guess it'd be best to buy exactly what you need, no one size fits all BS. Looks like I'm leaning more toward stock and going back in for porting later.
Not sure but it seems they are doing in it in-house. Here is the link to the listing, doesn't really give a whole lot of info, guess you'd have to call and talk to someone.
http://sdparts.com/category/cylinder-heads-0?page=1
I definitely want these heads to last and if the CNC risks them taking a dump in a couple of years, I'd pass.
I agree with the springs. I guess it'd be best to buy exactly what you need, no one size fits all BS. Looks like I'm leaning more toward stock and going back in for porting later.
These are our own CNC program, these are not GM CNC heads.
The CNC program will not negatively impact the reliability of the heads.
We actually have the heads for $1499 a set with .660" Patriot Extreme springs as part number SD8801. We can and are more than willing to put whatever springs you want on the heads and of course the price changes up or down depending on the springs. This is obviously a cheaper option than buying things more than once and changing it later and we are happy to do it for you.
The CNC program will not negatively impact the reliability of the heads.
We actually have the heads for $1499 a set with .660" Patriot Extreme springs as part number SD8801. We can and are more than willing to put whatever springs you want on the heads and of course the price changes up or down depending on the springs. This is obviously a cheaper option than buying things more than once and changing it later and we are happy to do it for you.
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These are our own CNC program, these are not GM CNC heads.
The CNC program will not negatively impact the reliability of the heads.
We actually have the heads for $1499 a set with .660" Patriot Extreme springs as part number SD8801. We can and are more than willing to put whatever springs you want on the heads and of course the price changes up or down depending on the springs. This is obviously a cheaper option than buying things more than once and changing it later and we are happy to do it for you.
The CNC program will not negatively impact the reliability of the heads.
We actually have the heads for $1499 a set with .660" Patriot Extreme springs as part number SD8801. We can and are more than willing to put whatever springs you want on the heads and of course the price changes up or down depending on the springs. This is obviously a cheaper option than buying things more than once and changing it later and we are happy to do it for you.
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If you looking for one of the BEST CNC'ed P&P head, I have the L92 WCCH Stage 2 with COMP Beehives. These hard have a few track runs only so they are basically NEW heads! Save yourself $450+ 
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I have a100% TR
https://ls1tech.com/forums/parts-cla...s-rockers.html
DM
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I would definitely opt to have at least the exhaust ports CNC machined, if nothing else. I think the intake ports are great, right out of the box, but the exhaust ports can be "better-flowing".
i'll go against the grain here and say do not get them ported.300+CFM out of the box can support a lot of HP.lap the valves in to make sure they seal.if everything looks good, bolt them on and don't worry about it.
just my .02,but the L92 exhaust port really doesn't flow bad.i think people get caught up in having the "ideal" intake to exhaust ratio,believing that you have to improve the exhaust to meet the "required" % of intake flow to have a good performing head.in most cases i don't think that's true.
look at the results of people just bolting on untouched heads,even with the slight drop in compression i've seen impressive gains for the money spent.
dollar per HP porting just isn't worth it for most street builds.just mill for desired compression and be done with it.
look at the results of people just bolting on untouched heads,even with the slight drop in compression i've seen impressive gains for the money spent.
dollar per HP porting just isn't worth it for most street builds.just mill for desired compression and be done with it.
Last edited by gtotoocool1; Mar 8, 2011 at 03:59 PM.
Maybe check out this test with actual results all on the same setup: http://www.hotrod.com/techarticles/e...4_casting.html
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not true.while i think those 3 you listed are quite good,there are others out there that put out a good product.(and some aren't on LS1 Tech)
Last edited by gtotoocool1; Mar 9, 2011 at 11:18 AM.
I performed a heads and com change on a stock block ls2 gto and all i did to the heads, was to clean the rough of sand casting off, on the intake and the exaust, and using a over the counter run of the mill 32 degrees duration the a4 car made 470 whp after tuning and 432 tq at the wheels... Yes with the l92 heads....
The as cast ports are plenty big as is...My experience is they work really well with cleanup of bowl area (so the seat interface is smooth to the port wall) , the usual guide work, and port match the intake to the heads and they will make great midrange and top end power. One of the main critiques of these heads is that the larger ports cause them to have lazy airflows at low rpms...why would you want to open them up even a little bit with the cnc enlarging the port. It is not like the port shape is garbage to start out with.
Match the combustion chambers to the bore, get the comp around 11/1 with a .040 head gasket and you will make lots of power, also I like double springs to handle those big valves. good luck.
Match the combustion chambers to the bore, get the comp around 11/1 with a .040 head gasket and you will make lots of power, also I like double springs to handle those big valves. good luck.
What's this claim based on? Those guys do killer work, but to talk so poorly about everyone else is simply showing a lack of actual knowledge on the subject.
Maybe check out this test with actual results all on the same setup: http://www.hotrod.com/techarticles/e...4_casting.html
Maybe check out this test with actual results all on the same setup: http://www.hotrod.com/techarticles/e...4_casting.html
i had a set of your ported L92's and they looked like
compared to the TEA L92's i have now i was just stating my opinion and if it makes u feel any better i think tsp's are budget ported as well.both have alot of rough spots around the ports and when spending over 1000$ on ported stock casting i was hoping for a better set of heads, but you get what you pay for and i have no regrets going with TEA and they shipped me both heads
