I have been doing some looking and have come to the conclusion that LS1/6 heads are not any better then regular SBC 23 heads. I know the LS1 motors make more power than the LT1 motors, but as far as I can see, I would contribute that to larger runners, 200cc vs 170cc. I know the LS1 motors take less timing to make their power because of a better combustion chamber and the injectors have better line of sight to the back of the intake valve, but is there any anything else I'm missing? The stock LS1 heads and LT4 heads flow amazingly similar in stock form, 200cc vs 195cc. Also, modded LT1 motors with h/c and all boltons make just as much power as cam and bolton LS6 headed cars with the same sized cams in each motor.

I guess my biggest question is, if the motors make the same power, why so much change from the SBC design?

Thanks
Jeremy

 

How about the fact that LS1/6 heads have a 15 degree valve angle?

The geometry between the two are quite different. I think the LS1/6 heads have shown their superiority over traditional 23 degree SBC style heads.

Jason

 

how about another fact.....

That 200cc runner is also longer than a 23 Deg runner, and the min cross sectional area is about the same, so the effective volume is not a good comparison. A better way would be to come up with a effective diameter of the ports, with a length and voluem formula.

Now small ports are only helpfull for velocity sake, too much velocity can be a restriction and velocity is also a product of flow and size. So if you have a port that is 10% bigger but flows 20% more than another port it has a higher mean velocity.

On the other end of this, same compare a LT4 head to a LS1/LS6/5.3L/6.0L head, your ultimate porting on those will be in the 320-350cfm range, vs a LT4 getting 285-300cfm, that along with some superior low and mid lift numbers will make the GEN III heads a better head.

The Gen III heads are closer to a small SB2 or 18 Deg Head then they are vs a raised runner 23 deg head like a Pro Action NASCAR head or a AFR 215RR. Those are good heads, but considering we are talking about stock castings, vs high end aftermarket ones makes it even crazier.

I've also never heard of a head cam LT1 based engine make 450-470rwhp like some LS1 cars.

Bret

 

That's the big ticket right there. For the LT1's to get those #'s you'd have to go w/ an aftermarket head, the stock LS1 casting can do it though.

 

Hmm whens the last time youve seen a heads/cam LT1 trap 120 plus? not often. Guys are trapping 125+ wiht LS1s with cams under 230 duration... street stuff hydraulic cams.

10 seconds cars with VERY streetable solid rollers (230s) are an LS1 privalege Damn them. Wait till some of them start doing some wilder stuff wiht solids... 346 cars are going to start finding their way towards the nines.

LS1 heads must not be that good

 

I havnt seen too many LS1 heads that flow over 300cfm on the intake, and if they do they are usually strong runners or complete dogs. I know the LS6 and 6.0 truck heads can do that though. Also the solid roller 346 cars arent any faster than most of the hydro roller cars. LG just came out with a cam for the LS1s that are making 460/420 on a hydro roller and ported LS6 heads, that is about as much hp as most solid rollers and just as or more torque than them.
I didnt mean that the LT1 cars were rolling 450-470, what I meant was that LS6 cars with cam and all bolt ons, since those heads stock flow close to what fully ported LT1 heads flow, are rolling and traping, in et, the same as LT1 cars with cam, heads, etc.
Wouldnt a fully ported, by some porter other than AFR, AFR 190 head flow close to fully ported LS1 heads and therefore in theory make and trap close to those similar built LS1 cars?
Let me know when you see a LS1 headed car traping 125mph+, I have yet to see one with cams under 230 duration without some FI or lots of weight reduction.

 

I helped put one together at our shop. 11.08 @ 125.4 1.58 60 ft. 2000 Formula. GTP 5.7 Stg 2 heads like everyone else ran, 226/226 cam. Full exhaust with cutout (no openheaders) and not a single bit of tuning either

Solid rollers arent running any faster than hydr. cars?

Jason99T/A and a futral motorsports (10.80 at 3550) car are solids, Jasons 10.6 at almost 130, at a hundred pounds (33 and change i beleive) and change more than the top h/c hyd. cars Id say thats faster.

These arent big solids either their 230 duration solids are likely just as streetable than a 220 hyd cam car. I think their might have been 1 hydraulic cammed car that snuck into the 10s... but LIGHT car.

Head flow numbers and dyno number dont always tell you the whole picture. Solid cams gonna make more area under the curve, and extend the curve much farther than an equivalent hyd. Seems liek a 400 hp LS1 will outrun a 400 hp LT1 every day of the week.

If LT4 heads are as good as LS1 heads, then someone throw LT4 heads on one of the fastest bolton cars with a stock cam, and see if they hang wiht the 11.30-11.50 bolton LS1s They look good in numbers but just dont seem to perform

 

I have another question while I'm thinking of it. I have seen a lot of /c combos on LS1 and LT1, why do the LT1 have not only a flater torque curve but also have more lowend then the LS1 cars?

 

this link might help your LS1 low power complex http://xs-fx.com/list/ls1tech_list.php

There are 50 LS1 F-Bodys in the 11's with just bolt ons, you need a H/C combo to do that with a LT1.

I still don't buy the LT1 has more low end theory. It seems that way to the butt dyno but the LS1 has so much more upper end power it makes it feel like a weeker engine in the low end, which in reality it's not.

Bret

 

Also, while your answering all my questions , how can the LS1 run more lift then the regular SBC design without valve float? Does it have something to do with the fact that the LS1 has a larger cam journal? Also the link doesnt work.
I was doing some looking and Comp recommends the 977 springs with the XE-R lobes for the LS1, that is a lot of spring pressure for a hydro lifter. Would it I be correct that since the LS1 cams are designed for 1.7 rockers where as the SBC is design for 1.5s you could run 1.7 rockers on a SBC and run as much lift without a valve float problem, within reasonable lift ofcourse?

 

try this one http://www.ls1tech.com/ubb/ultimateb...c;f=5;t=004081

I'll get back to this on the other part of the question. 977's need a good lifter to work with them, Comp also recomends that, even thought you can't buy them.

Bret

 

Isn't another difference the valve spacing?

IEEI for the LT1 vs. IEIE for LS1, etc.?

 

Here is two LS1 Solid rollers in 10's

Allan Futral of Futral Motorsports
Best Time: 10.72@128.62 1.48 60' 12/2002
Race Weight: 3440 lbs

Gordon Sevin (build by Allan Futral)
Best E.T./MPH Run Best 60' 1.500
10.66 @128.42 1.528 60' Race Weight 3395lbs

Oh and here is a Cam/bolt on only LS1 from Allan, untouched heads.
Mike Hoffman 2000 Z28 A4 (on stock rearend)
Best E.T. 10.98@121.44 1.45 60' 12/6/02
Race Weight 3300lbs


Show me some Stock displacement LT1's in the 10's without poweradders.

Later,
JoMo

 

Isn't it actually E-I-I-E-E-I-I-E?? No biggie!

I agree that probably has "something" to do with the difference as well. Whether it's that it keeps the temperature in each of the combustion chambers more even.........who knows?!

Also, remember that overall the LS1 is a lighter engine than the LT1. And fine if you can reduce the weight of an LT1 car to the same or less, but there's less weight in the front of the LS1 car which will help for quicker weight shifts and better ET's.

 

uh. like others said, I don't see how a H/C lt1 car makes as much as a head/cam LS1 car. lots of 440+rw LS1 hydralic cam'd motors. highest hd cam'd heads/cam LT1s I see are 420, tops.