pauldana

Being all things equal, how much more Hp can you get from a LSX over a SBC.... Talking like a 427 LSX in comparison to a equally equipped modern built SBC.... Both same compression Pistons size exhaust same size AFR heads everything..... The difference in HP would be found in the type of head ports and angle of the valves and whatever other design differences there are .... Again... As exact as possible all parts and all being modern.. FI and everything ..... So what HP difference in design alone do you think there would be? I would think torque would be equal being that it is developed via compression and CI.... Thoughts?

I was thinking like 10-20hp on a 600hp motor

toobroketoretire

I'd guess about 15%.................

a striper

I don't know about an all out max difference but I like the way a similar power LS engine seems to do it with about a 15 degree smaller cam than a small block with good heads.

Shark Racer

You can get heads for small blocks w/ tighter piston to valve angles. That would narrow the gap a lot.

IMO, the big advantage to the LS series is (A) cheap HP/$ (to a point) and (B) much better gasket design.

Once you get past ported L92 heads, the $ for incremental HP climbs steadily. You can build a 500 hp L92 based engine with a mild cam for very little cash compared to what would be required to do the same with a G1 SBC.

diehrd

if built equal . the SBC wins .. Here is as close to a heads up as you can ever get and look it is using the same oil pan i am

http://www.hotrod.com/how-to/engine/...own-ls-engine/

jim2527

I think its much easier to build a high HP engine with the LS platform. Over in the C5/C6 there're a bizzilion guys with 1000rwhp cars.

doorgunner

Hmmmmmmmmmmmmm.......what would I do with the EXTRA 650 H.P.? The engine in my '06 Escalade "yanks that 5500 lbs. around just fine"!

gkull

I would never build a high performance 427 -447 ci G1 again. It is just too expensive. All my friends have gone the LSX route. They already have 2.200 intakes and dry sump

To get the same HP out of a gen 1 you would have to buy these brodix 11 degree heads with 2.200 intake valves. These are the heads that 410 Sprint cars now use. You also see them on 434 441 and 447 ci dirt track motors. Probably $10,000 with valves and springs. Then custom headers.

LSX motors are also dry sump. That is a 30 - 40 hp gain on our G1
motors when you install it.

My ultra4 racing friends have been buying these and with a cam swap and FAST intake they are right around 700 - 720 hp with 600 feet pounds of TQ. Cheap alternative.

http://www.chevrolet.com/performance...s/lsx-454.html

or if you want it turn key they just buy these.

http://www.chevrolet.com/performance...s/lsx-454.html

pauldana

Where this came from, is I have a good friend that runs a carburetor repair shop, and has been in the speed shop business for like 40 years... Anyway, he and his son and I were talking about builds and he is looking for a new C6Z... and this particular one was claiming 600RWHP but the mod sheet was limited, he was running 11.1 compression and a bigger cam I am sure,, but not major head work or anything else... now I know I went ***** to the wall on my build to get 510RWHP.... I do agree that the LSX by design can make more HP... but again,,, how much more?

my heads flow 324 240 @.6" 220 runners.. AFR

312 246 @.6 215 runners AFR LSX head
328 252 @.6 230 runners AFR LSX head

so something between the 215 and 230 offered would be very close to what i run with the SBC head... There Exhaust seems to flow a bit better on the LSX side, but the intake seems to be a draw, or if anything leaning towards the SBC side..

gkull

Might be time to pull out the BS meter! Without power adders 600 RWHP is hard to get out of 427 ci and be streetable. The Texas speed 700 at the crank might make 550 RWHP

cv67

Flow #s dont tell the whole story on power
Think theres better alternatives out there

Ask Mamo about his LSx 383, know his 346 with a tiny cam made around 480rwhp. If all specs were the same the sbc would get slaughtered how much can you get to the ground though

I have a larger head same compression almost 20 deg more cam timing I think he woulda smoked me;ridden in his car it was a beast.

On the 700 cam only claim hmm.. many dyno #s out there are fluffed to get more business


I say be happy with what you got

gkull

with all things being equal. The LSX's only gain is the 30-40 hp dry sump system

SuprJames

Exactly! When you bust one open and see all the o-rings vs. the old cork or gooey gaskets, you'll really see the difference. They just don't get the leaks like the Gen I's do. That and the LS motors love power adders. Oh, and 6 bolt main.

pauldana

What about the head design itself?

Chris Strub, my Cam spec maker, ...... He built the same cam for both Danny, my sone, and I... Mine went into my SBC, His was going to go into his 427 LSX C5 Guldstrand... his build was almost exactly the same as mine.. his Linginfilter heads stated about the same flow, just slightly lower... And Chris was still under the impression that the LSX would show about 10-20 hp more on the Dyno...

pauldana

And I am NOT asking or care about HP to $$$ spent,,,, that is not the question or answer to this thread,,,,

The only thing I am looking for here is how much more power, if any, would a equally built LSX to SBC be???

diehrd

I think 2 identical motors will post up close numbers the sbc more torque and LS top end HP . Side by side in exact cars and I think it will come down to the driver

C3 Stroker

I'm kinda agreeing with diehrd, here. All things being equal (and that's the important word, here), equal airflow, equal dry sump system, etc., the output should be the same.

tt 383

This really is no different than B/O/P/Ford/Mopar... just a different way to get there. Aftermarket is limitless when budget is thrown out the window. The advantages on LS is the raised cam core and core size, high ratio factory rocker, stock head flow in cathedral or square port and accompanied intakes and ECU/tuning support and cost, maybe a slight edge in chamber due to valve angl, bay to bay breathing if not dry sump. Price point on this stuff makes it very appealing. I dont see at the point of aftermarket cost, a reason to go sbc/ls though, unless class limited or weight limited for rr/autox/hpde stuff. Why would you use the same size head though on both engines?

One thing to note, the ls heads in 235 flow a little better through the lift plots, but on a 3.9 bore vs the 4.125 for the sbc, would think they flow a few more on a big bore...

Shark Racer

Yep.

If they're filling cylinders at the same rate with the same amount of air and pushing it out at the same rate with the same amount of air the power output is going to be the same.

The LS's big advantage is that it comes stock with better valve angles so the average head is better. You can get heads with better valve angles for SBCs. You can also get 23-degree heads that flow better than stock LS heads.

An AFR 195 Eliminator head on a G1 small block with a decent roller cam will make more power than a stock LS1 with a similar roller cam. Put nice AFR heads on the LS1 and the LS1 takes the lead.

Assuming equal flow through the heads and cams of similar ramp rate, duration, etc, LS engines have a higher rocker ratio than small blocks so the LS will edge out there.

mrvette

All I know is that my little 350 .30 over roller FI engine will make the tires very sad through two gears off the 200 4r......336 rear, for my simple street driver, anything else is a waste....