mr chevy

I use the 317's how can I make power over the l92's

Paul57

How much power are you trying to make on what motor?? The 317's can be CNC ported for more power but I don't know how that compares to the L92's (directly).

1badeagle

iTrader: (9)

You going to need a good porter and milling to up your compression. Even then the L92/LS3 heads are the way to go. They flow amazing out of the box and they are dirt cheap. Port and mill some L92 heads and make big power.

Paul57

Beware...The biggest flow numbers do not always mean the fastest car.

melsie68

iTrader: (8)

Get the 317's worked or get some 243's. You will be able to run with the L92 if your cam and induction are ironed out.

tennerv8

iTrader: (7)

L92's flow 320 cfm @.600 lift, right out of the box uncut in rough cast. They have 260cc intake runners which are larger than most aftermarket LS heads. They also out flow a lot of aftermarket LS heads. With an intake runner that big they do suffer a bit on the air speed. They suffer from low velocity. Hell they don't even wake up until 3k rpm's. My L92'd 6.0 feels lazy down low because of the slow moving air in the runner. But is not that noticeable because the truck only weighs 3k lbs. This is where a 317 head can out perform an L92 down low, since they have a 210cc intake runner. So they have more velocity at low valve lifts and lower rpm's because of the smaller/narrower runner. But beware...when an L92 head comes alive...I hope you're going in a strait line 'cause the tires WILL break loose. I can smolder the tires at freeway speeds.

topbrent

iTrader: (1)

Broad strokes answers.

L92 heads are great, but they require more thought on cam choice due to the large port. - Very easy to overcam.

The smaller cathedral ports on ported 317/243 heads will be a bit more dummy proof regarding cam selection, and will be more tolerant of overcamming.

The moral of the story....pick the right cam and you can make great power. (regardless of head choice,)

Paul57

Seems like you could make a fairly good case for L92's on a track car and 317's for street use. GM uses very small cams compared to what most of us are accustom to so the L92's work great on the street, for factory cars.

I have also read that on a 4" bore the L92's cause a flow restriction because of shrouding the jumbo valves...when you get into the 460+ rwhp range.

bad67ls

iTrader: (2)

thats the issue i am running into now... no one seems to have a good answer, or be able to agree on what works on a carb'd ls2

help!

Paul57

This article may help answer some questions. Several cam tests with L92 heads...
http://www.hotrod.com/techarticles/e...camshafts.html

topbrent

iTrader: (1)

Yup, legitimately there is the that intake valve shrouding issue... and then you go and read about the track times that DMMizell ran with his pump gas, fox body, LQ4/L92 combo and it all seems somewhat moot in the end.
Pushing 2900lbs to 9.87@137 with a stock junkyard longblock is pretty dang impressive in every way measurable.

If your goals are in line with Dave's combo, it is a track proven setup.
Needs rear gear and a great 4k+ converter to make it come to life.
Follow the recipe and it does perform very well.

http://www.youtube.com/watch?v=fn719sol8hE

bad67ls

iTrader: (2)

i am running 243's... seems to be little info out there.

topbrent

iTrader: (1)

Nah dude, there is tons of 243 info on this site. You just need to search.
There are so many great running cars on this site. It just takes some patience to sit down and read through all the fluff.

bluecajun5.3 has put together a good low 10's runner, and it will just get more impressive as time progresses.
https://ls1tech.com/forums/carburete...d-mustang.html

Look at Speedtiggers setup for a quick yet street friendly combo.
https://ls1tech.com/forums/carburete...-carb-cam.html

bad67ls

iTrader: (2)

the mustang is more of what i am looking towards...but no head work or flycut. similar weight, and i am running a 5 speed. if i made it into the 50's or 60's i'd be happy.

sorry to jack the thread fellas, it just seemed to have the most current posts in a similar thought range. thanks a bunch for the info!

Paul57

The data I have shows the 243's flowing about 5% better than the 317's. So, they are in the same class along with the larger combustion chamber of the 317. I am having a hard time believing GM gave those two heads identical port volume and valve size yet altered one of them enough to gain/lose 5%. I wish one of the shops could confirm that info on back to back tests of these heads. It seems like the "production" way to do things would have been to just alter the combustion chamber size.

mr chevy

Thanks guys I was thinking the same thing with the cam

Doug G

Do you mind sharing/posting/PM ????

Prorac1

iTrader: (4)

From the searching I did for my project, flycutting the pistons with the L92 heads and a carbed setup, makes the differance between a combo that moves out, and a combo that FLYS. The flycuts give you the ability to put a cam profile in that compliments the heads better. Just my .02. Eric L

Paul57

This is my top secret source. Give me your views/thoughts.
http://www.theturboforums.com/smf/ls...swap-info-etc/

rooster2d

iTrader: (1)

I always pondered on the ability of making decent power with the l92's and a small cam. I know many of us don't even consider emissions, but wouldn't this combo help those that need to pass?