yep..ls1s are very good with their 15 deg. heads. Too bad we aren't allowed to compete with the same.

Keep givin em hell joe

 

The valve angle doesn't really play into an advantage with that head... Mostly since there is so much development in the 23deg SBC head already. I've actually never seen a LS style head outflow the best SBC heads i've ever seen. The problem is a LS head is consistantly a better head on average, where there are only a very few excellent 23* SBC heads out there.

I'm not fishin Joe, if I was going against you in a class I'd probably bring better bait.

So your stepping up for the Super Mod and Extreme Mod classes this year?

Bret

 

I'm trying my hand at PRO Prostock this year...should be interesting since it is a weight to cubic class and I can drop another 100 lbs out the car.it will prolly take 9.0's to even be competitive in that class but I got to start somewhere..f-body series type races there is nothing to gain as of yet..So I guess you have to go forward or step back at this point...

 

True on the f-body series....

I hope your taking advantage of the EFI loopholes in the rules....

"Single throttle body required, maximum throttle body size 95mm...... Carb-style manifolds may be retrofitted for EFI fuel injectors."

The NMRA equivalent doesn't allow that last time I checked. I've been interested in that class for a while now, except I give you lots of credit running a Chevy in that class. I still think a mean SBF with Victors on it is the way to go. Then again your chassis works extremely well and that's more than half the battle.

Dam.... Sorry about jacking the thread boys.

Bret

 

thats ok..no one cares about results unless they have LE stamped on the heads..so we can talk about anything in here we want and no one will see it..lol.

 

Joe, dont treat "flyinz" too nicely, i dont want him whoopin on this stock bottom end car too bad j/k

very nice numbers man! do you think you would have been able too achieve those numbers using the stock pcm?
also, what does your car weigh? cant be too much i wouldnt think

keep it up man, i love the threads where you get the handful of top LT1 guys in here talking it up



who wants too port my intake for me? i know its holding me up some

 

My best pull on the stock pcm was 452.4. that was after years of tuning on the lt1 heads and then tweeking that program for the new lt4 heads. This 454 was after an initial pull and then pulling some fuel out of the program joe sent me to start with. So very very little tuning..I just basically pulled about 4-5 % out to see how it was gonna act. So yes..I think this number was possible with stock pcm because it was making the power...but I also think that fine tuning on the dfi is gonna make this number go up. But...I'm not about dyno numbers..I about track results. The car weighed in at 3420ish on the best runs on my old heads. At the thunder shootout where I ran my coasting 10.8 I was 3330 lbs. Ive taken the pass seat out now so that puts me at 3300. Not a featherweight..not a heavyweight...but a middle weight.

And about my outting last night. I forgot how much I don't like the little track I went too. Its slick, bumpy,groovy and very narrow lains. I was all over the track..the car actually bounced so hard in second gear one run(my best of the night actually) that it actually got the rear end light enough to spin the tires in second and I had to pedal it. I though I was gonna hit the wall at least twice and tried to cross the center line a couple times a few runs. The best 60" I could get was a 1.58 and to get that I had to leave easy and let it bog. The the car was hoppin and following groves all the way down the track. Very nasty runs. Best of 10.93 but did set a new mph of 127.5....even after boggin in first and having to pedal the car in 2nd. I was fighting the car so hard going down the lane I was short shifting at around 6600 because I couldn't pay too much attention to my tach. Oh well.going to NPR next week hopefully with a new coil....because it was still acting up on the top side and even stuttered some in the middle of the gears that run.

 

Awesome numbers man, your setup defiently makes me rethink going with the 383. I just wish I was running the times and making the numbers that you guys are making, maybe one day. Does SAR2K do head porting for Thunder?

Good luck with your new setup.

 

I don't think the valve angle plays that big a part with the LS either Bret. The real beauty of the ls head as I see it is it's port layout. All the ports are near identical... no dog-leg to the right or left. No paired exhaust ports. More equalized flow from cylinder to cylinder. It's not on par with race heads IMO, but it's not a bad compromise either, especially when you consider what can be done with a hydraulic roller which can't be used on 1st gen race heads.

Tim,
Big congrats to you! We should also thow some accolades to Steve at Thunder Racing. Nice job.
I'll be glad when you guys get some of the tuning issues ironed out so we can see what she's really capable of. Good luck.

-Mindgame

 

Well let me get a post in before the F1 race starts....

I agree, the port layout and the awesome injector angle make these things work perfectly. The other really cool thing about the LS head is the cathedral port layout, I listened to Phil Martin talk about head port shapes and he stated that a tall port will give you better drivability over a wider port. I guess that's another bonus to the LS casting.

The paired up exhaust valves on a SBC is always bad too, the spread port stuff helps this, but even then getting some extra coolant in there between them is the only way to get the motor to not have a retarded hot spot there.

The one good thing that evens out a 23 SBC head and a LS head is a offset rocker and a solid roller, might even give the advantage to a good 23 deg head then. We still haven't seen these steps taken on a LS head yet and if they are this good early on imagine what will happen with more development.

Bret

 

word is cathedral ports are being ditched for rectangular....so evidentally not much of advantage...

 

Well when its one of the leading head porters at a Cup shop I'll take his word on it. Think about the LS engine, when have we ever seen that big of a port in volume on any street motor relative to the cubes under it. Plus they make the port act smaller with the longer stroke and longer rod over a standard SBC. Then when those things get ported they are monsters.

The LS7 OTOH would have to be sporting a 260cc port for it to be comparable volume to a LS6 setup. That and when you basically take a C5R head and make it a port for a steet car it's going to show it's orginal roots as a SB2 port. It's less of a whole new design than the LS was, that port had to fit into the same external head casting. The factory would never make a offset rocker motor unless they had too. Remember that's a 360cfm head that makes 500hp, you and I would be sick if we had that much head on a motor and that little power, but we build motors for a different purpose.

Bret

 

Theres alot of "dead air" in the floor of a ls1/ls6 runner.....what I made reference to is GM is going to rectangular port over the cathedral..And yes there has been some experimentation with a cathedral port design that I know of also,and know quite a few cup porters myself and builders.. have to remember I live in VA.. I've seen test parts that prolly the public will never see...

 

Yeah the effective cross section of the LS head is not as efficent as most heads.....

 

Thanks, steve use to port the heads for thunder. His heads were on the 505 rwhp 346 hyd. cam motor that jason 99ta went 10.3 at 132 with just to name one. But he doesn't do them anymore.



Oh yea..I give any new gains to steve...and a few outher people...joe is one of em. He did these heads and intake and that all that I changed besides the DFI system(thanks joe for the tuning and the advice). But the coasting 10.8 run was done on a stock pcm. Of course thunder has been a great help also. I will get it ironed out..my new coil got here today so I will be throwing it on and seeing if I can get this thing flying.