bluethunder364

iTrader: (5)

Hi
I just got off the phone with a high performance tech rep. from Scog. Dickey because I wanted to know the runner size on the L92 head and the combustion chamber size. 260cc and 70 cc respectivly. I'm ok with the chamber size , but is the runner really that large?? Is that true? Just wondering how a runner size that large if correct would perform on the street.
I plan to race my car for fun at the track some but want to make sure it is streetable as well. Plan on these heads for my 6.0 LS2.

Thanks

Scoggin Dickey

iTrader: (34)

That is correct. Its been an issue for years with street engines trying to run really big intake runners...you need to excite that intake port to make great power. You can do that A) with more cubic inches (more volume in and out of the engine) or B) spinning higher RPM (again, more air in and out). The problem is that these engines aren't real big cubed or built to handle big RPM's from the factory. Can they make great power? YES. You just need to pick the right combo to get it done! Let me know if I can help get your setup dialed in!

VH5150

Yes, they are 260cc its a big port, I have a set infront of me right now... It makes the LS6 head look like ****... Just set'em up w/ the right cam and youre good 2 go

bluethunder364

iTrader: (5)

Matt and VH5150, Thanks for your input, I did read an earlyer post stating that is the correct size......Wow I was a little concerned but you have put my Chevy brain to rest!!!
I will call on you Matt for your assistance. I plan to order the L92's as soon as I gather up the funds. I will need help in the cam selection process. I plan aslo to run an 850 DP with the stand alone MSD controller. I have the Hot Rod magazine write up to follow to some degree. Another area of concern is wheather to run a daul plain or single plain intake. I know the single will make a little more power. Just want to make sure it is streetable. Pls feel free to advise. Thanks....Chris

JS

iTrader: (4)

I think this depends on rpm,size of engine and camshaft design.To say they make the LS6 look like **** is a stupid comment,I would think on a 346 to 400 CI that a PORTED LS6 is more then enough head to make 500RW and better overall power/tq than a L92 from a data point of 3000 to 6800....

Scoggin Dickey

iTrader: (34)

^^Agreed!

Busted Knuckles

There are a helluva lot more things than runner size and CFM that makes a good cylinder head. Cross section, shape, bowl shape and size, valve job, etc. You can't compare these runners to the old smallblock stuff any more than you can compare 'em to big block heads.

Edit: Matt, I was just pointing out that there's a lot more to making power than port runner size or flow numbers. An SBC head with 230cc runners is generally sluggish on the bottom end and takes a lot of revs to really get into the head's power band. But with the complete design change, these 260cc runner heads maintain more than acceptable port velocity even on smaller cubic inch engines. Speaking from past experience with AFR big and small block stuff, they have very impressive flow bench numbers but make more power with a different valve job where they actually flow less on a bench. With so many combos yet to be tried and tested with the L92 heads, we don't really know how much they're capable of. Not since the SBC Vortec head came out in '96 has there been such a power-making, great bang for the buck cylinder head, IMHO. They'll be on my 402, I just can't pass up the deal GM's making us on 'em

Scoggin Dickey

iTrader: (34)

Nobody compared them to those heads Did you have anything to add for the original poster, or were you just pointing out the known differences in SBC and BBC heads?

JS

iTrader: (4)

Correct there is much more to it but lets face it there too big for most 400in motors.

Over a 4.06 bore and a longer stroke I would jump on the them but for a 364 to 400CI engine there not needed...

VH5150

Well boss, according to all of my friends that run 7sec in the 1/4 say the LS6 cant hold a candle to an L92... when setup properly.

I think ill take their advice and not yours... you be happy w/LS6 heads and ill take my L92's any day....

When setup properly ( motor, cam, ect) an L92 will **** all over an LS6 head.... pound for pound... An LS6 was designed for a 3.9 bore, an L92 was designed for a 4.0+ bore..... common sense. reason why L92's arent making " as much power" as they should is cause people dont set'em up right...

I sold my ported LS6 heads & FAST intake, so I could UPGRADE and GO FASTER w/L92/L76 setup... Granted the L76 intake sux,but ill work around that...

Keep in mind this new setup is on a 408, my old setup was a 346....

When I told my builder I wanted to keep the LS6 heads he laughed and said " those heads aint gonna work, you need an L92 head"

Do what you wish, Ive made my desicion...and im happy....

VH5150

Now you are making sense...

JS

iTrader: (4)

If u knew how to read u wouldve seen I said on a 400CI or larger engine,u know a bore or 4.03 min but more like 4.06 to 4.155...So we agree that these heads are NOT worth putting on a LS1 or LS2 under 400CI

The valves are heavy,the ports are huge and unless u run a GIANT cam with a big split and spin it to 7000 they dont work very well....

Now on your 408 I would go L92/LS3/LS7 toot sweet....
The big stroke and bore loves this type of head,remember the BB CHEVY or are u to young to remember those engines

Lastly your friends run 7's....aWOO WOO....
Can I ask u what do u run??????

I could name 20 people that I know who run real well but who cares bro
We have name for guys like u in Philly-------------->Joe Average

Its all good bro,good luck with the setup...

VH5150

I run nothing now... but that will all change soon... If I wanted to run 6's,7's, 8', ect I could but I dont want to... I dont have the desire to do that. I want a fast, daily driven, street car....

If im joe average.... Then what the hell are you???? you are wacked as far as im concerned.... Im done argueing. and bashing, hopefully you are too...Im done w/you....

bluethunder364

iTrader: (5)

Man this is getting personel, All I wanted to know was the runner size. Now I'm bummed. If I have a little O 6.0 should I not get these L92's after all?? Not planning on a over bore to 408 cube. For the price of a L92, what is out there that will do the job??

VH5150

For the price there isnt much at all, unless you find someone who wants to unload a set of heads cheap...

The L92's are good, maby not for youre application... Im sure they could work for you but you would be leaving alot on the table... Unless you plan on putting a big cam in the car and all of the supporting mods. Im sure there are some people who have put L92's on a 6.0.....

If I was you I would take the LS6's off the car and have'em ported and put a matching cam in there and you will be more than happy..

Good luck..

bluethunder364

iTrader: (5)

I plan on using a carb for my set-up, so I need a set of heads that will match up to a carb manifold

VH5150

GMPP makes a carb manifold and so does edelbrock for the LS6 heads..

bluethunder364

iTrader: (5)

So what exactly are LS6 heads? Will they fit a 4.00" bore from a 6.0 liter block??
How well do they flow etc. Are the casting #317 that came on my motor of any performance value?? Do they need to be ported?? I'm pissed now because I was all set to do the L92's Thanks for your help

VH5150

What kinda car do you have, and what year?? a GTO??? 243 is the casting number on the head...

bluethunder364

iTrader: (5)

Are you ready......1991 Mazda RX7, current set up SBC with E-tec heads, Dynoed @420 HP. Switching to LS power. Do you know if the #317's have any flow data? I know from the article in Car Craft that they tested a 6.0 with iron heads after just a cam change and made 483 HP. They then went on to do the L92's and made 506 HP with a .571 lift cam @5800 rpm. They made more power further up the rpm scale. So not sure what the plan is now