How much power are you trying to develop?
What type of compression
What application?
The L92 heads aren't everything they are cracked up to be (very large intake runner not particularly efficient with a very mediocre exhaust port). They produce OK power when worked on but aren't the holy grail Gen III heads by any means. Good value for those on a budget though.
I have built some very impressive pump gas engines (with AFR cathedral port heads) in the low 600 range that will run all day long on 91 or better octane with a really spot on tune.
Building a complete 407 CID engine right now with our new 215 AFR cathedral heads. I anticipate that engine might produce 610 HP and 550 ft/lbs if everything falls into place like I hope....and this is a very drivable combination with a 242 single pattern hyd. roller with a smooooth 114 LSA. It will have razor sharp throttle response and great part throttle grunt with only a 215 cc intake runner on a 400 CID shortblock (Gen III runners have a smaller cross section than a comparable Gen I design given the same cc's). It's probably close to the equivalent of running a pair of our 195 Comps on a 406 Gen I piece.
Not an inexpensive build by any stretch but a remarkable output given the broad scope of its demeanor (you could literally drive to work every day in traffic with the A/C on in the combo mentioned above....then drive to the track and run 130 trap speeds in a 3400 lb ride....ET dependent on choice of tire and how aggressive you dare to be).
Here is a quick street clip of my former 383 with a 242/248 solid roller. It still managed 21 MPG in 6th gear on a long highway run and produced 615 HP on a SF902 engine dyno (on 91 octane). Car went high tens in pure street trim @ 130 in so-so air (1200 ish D/A) with purposely soft 1.7 ish 60 foot times. I always kept the tires aired up so I could drive home instead of getting a lift on the flatbed. The C5 drivelines are stout but far from bulletproof and I have had my share of expensive broken diffs (cracked housings, broken output shafts, etc.).
http://videos.streetfire.net/video/540- ... _58201.htm
Long story short....IMO even the best 23' stuff of today wont quite keep up with a really dialed in LS combination....but the gap has closed a bunch with the recent crop of really good 23' heads now available. Perhaps when discussing an all out high compression drag race set-up its even a little closer in performance (comparing a killer Gen I set-up versus a Gen III design), but the beauty of the Gen III stuff is the power you can produce on pump fuel with only 28-29' of lead for timing....it has a better chamber design and is extremely efficient. Its a very impressive platform not to mention easy to work on and very lightweight. Also, much more stable in the valvetrain department with hyd roller cams in the low .600 lift range stable to 7200 or so with the right spring and valvetrain set-up. Once again....another perk if your trying to build a dual purpose pump gas hero.
We are about to launch a new 245 cc cathedral piece that flows 360 CFM and 265 on the exhaust. I'm building a 447 CID shortblock right now to debut and feature those new heads on sometime in January likely. Its a reasonably aggressive pump gas build with a solid roller (260/266 on a 114 LSA)....hoping for 675 HP and 600 ft/lbs. Might make closer to 700 but the long intake runners of the FAST intake will likely force an early power peak and limit my ability to get there. The shape of the curve should be explosive though and I expect 500 ft/lbs of torque at an extremely low RPM.
Nevdos, if you're discussing a combination with lots of compression and the right cam I would go with a big single plane intake (Super Vic) and go with a carb to keep costs down and keep it simple. With the obvious power these properly set-up pump gas engines are capable of, an aggressive high compression engine could really haul the mail for you if you select your parts wisely.
Will share the 447 results with you guys when everything finally falls into place in a few months....
-Tony
so it works very well
) ,but i am looking to pick it up some on motor is all(as is everyone lol)