Johny GTO

ok wait. in my pm to you i thought you had an LS1 for some reason. So the motor you have is a 6 liter truck version of the LS2, correct? The 317 heads are the large chamber version of the 243's, correct? SOmeone let me know if i am right.

As for what i said in my pm to you, it still applies. However, if the heads you have (the 317's) are the same as the LS2 and LS6 243's, now you dont have to buy a used pair and will save about $500. If thse 317's have larger chambers than the 243's, it will cause lower compression. Good for a forced induction (turbo\supercharger) motor, but not a NA motor. If the heads can just be milled down, go that route. However, that might make the deck thin, so it would probably be best to see if you can sell these heads in the for sale section for around $500 bucks, and then buy a set of 243's. Of perhaps find someone on here who has 243's and is looking to lower the compression for a turbo setup and trade them heads.

As for going with the L92's, i dont suggest it. Those heads perform better on a larger bore motor, the 4 inch bore of a 6 liter is a bit restrictive for the L92's. Also, it wouldnt be cost effective. YOu will spend around $1500 or so for these heads along with a L76\LS3 intake manifold, perhaps more. The results you get as compared to a nicely worked set of 243's (port, polish, valve job) are not worth it at all.

I sent you a pm clearly detailing what i would do in your position, but here is a summary.
If your heads are the same as 243's, keep them. if not, trade\sell them and get a used pair of stock 243's from the "for sale" board. Contact someone who will do head work (port, polish, valve job, etc) and will spec a cam for you. This way they can match cam to the heads nicely for you. They should ask you exactly what your goals are with the car, things like how much horse power you want (peak and under curve average), what you want your torque curve to look like and where it comes on, what the desired operating range of the cam is, what the car will be used for (track, weekend cruiser, DD), cam behavior (lope + idle characteristics, does it have to pass emissions, etc), and what other mods are on the car (type and size of headers, intake manifold, exhaust system, gears, etc).

When you call a shop about working on your heads and speccing your cam, ask them if they happen to have a used FAST or used LS6 intake that they would be willing to sell, as well as long tube headers for your car. PErhaps this way, since you are buying everything with them and spending a decent chunk of change, perhaps they will cut you a break on the price. It cant hurt to ask. It will also save you the trouble of buying parts from 4 different people, tracking stuff down, etc.



Dont get me wrong, i am not leaving out other shops because they cant do the work or because they arent bad *** guys who do great work. I just don't know which shops also do cylinder head porting and polishing, and i dont know which shops also do custom cam grinding, let alone what vendors and shops do BOTH of these. The people i named do BOTH head work and custom cam speccing.

Let me know where you are located, perhaps i can point you in the direction of someone good in your area or at least close to you. PM ME.




p.s. I actually still have my stock 243's from before i modded my GTO. I totally forgot about them. I never bothered to sell them, and they have been sitting in a box in my closet for a year or so. Not sure if i want to sell them. hmm..

Scoggin Dickey

iTrader: (34)

L92s will blow stock 243s out of the water. They are killer on a 6.0, and I would recommend them.

Johny GTO

yes, stock for stock the L92's will trump 243's. On a 6 liter 4-inch bore, the L92' still beat the 243s, stock for stock. HOwever, if the 243's are worked nicely they will out perform L92's on a 6 liter. This opinion comes from observation of et's and mphs in the quarter, and dyno results.

Scoggin Dickey

iTrader: (34)

If you're going to compare non-stock heads, hows about we CNC the L92s too? We've seen 30-40 flywheel HP from simple CNC porting on L92s.

243s are killer heads, but if you're buying heads you don't have and have a 4" bore, the L92s would be my choice.

Johny GTO

i believe he said he has 317's for heads. Those are the low compression, larger chamber versions of the 243's right, or am i way off?

keeping in his budget, i think he should sell the 317's he has and get some used 243's somewone pulled off. That would be price neutral. Having the 243's worked would be cheap and give good results.

As for L92's on a 6 liter 4 inch bore, yes they do give good results. It seems like the average HP they pump out on a LS2 (4 inch bore) with proper cam selection is around 450-460rwhp, with the higher output motors are around 480rwhp. However, on the LS3 motors (6.2 liter, larger bore) they often come in around 500rwhp with a good cam.

On the 4 inch bore 6 liter, i think his worked 243's can readily put out around 460-470rwhp with a good cam, and since he will only be paying for the port\polish work on the heads, this aproach would be much cheaper than him buying some L92's and an L76 intake manifold.

squee

iTrader: (16)

Yea, they can hook you up, but be prepaid. There gonna ask you for everything from cc of the combustion chambers to what gears are in the rear end to tire diameter to weight of the car.

Johny GTO

thats good. to truly spec a cam to do what the person wants, all of these details are needed. That is why to do this right, this gentleman needs to get his package lined up first. Meaning he needs to decide which heads he is going to use, which intake manifold, etc.

It is this reason why i suggested getting with someone who has heads and cams, because it will just make the task easier for you. See if anyone on here has some stock 243's that they will trade for your 317's, most likely cause they have a forced induction setup and want to lower compression. once you have the stock 243's, look to get them worked over which will likely run you around $600 or so. Then you get your cam spec'd to match these heads.

squee

iTrader: (16)

Exactly.

Country1982...

I was reading this post as I recently traded for a motor with this cam the bigger of the thumper cams from comp cams the motor sounded nasty before we pulled it out of the truck however I had planed on putting it in my daily driven truck and after talking to my local tuner he informed me that it has to have a big stall converter to even run and I can't take off at every red light at 3500 rpm but yes they do make this cam for the ls platform

grinder11

iTrader: (1)

The last guy posting before you hasn't been active here for over 7 years, and thread is 13 years old.......After 13 years of tech has gone by, the cam specs may not even be the same anymore! Better to start a new thread!!

Country1982...

I didn't realize the thread was that old and I read the specs he posted and they seem to be the same as the motor I traded for for all I know this guy is the one that built this engine as it was built 7 to 10 years ago drove mabye 50 miles total parked and sat for years but I will start a new thread