i6overboard

iTrader: (3)

Just seeing if anyone has any info on if GM will ever move to LS 4 valve V8? Ford has already made the move with the GT 500 platform and the new 5.0

All of the LS motors are very efficient and can make plenty of power, but the pushrod design has been around for decades and is basically imo old technology.

I just feel that it would be step in the right direction if they were to introduce a LS 4 valve motor.

Just looking for some of yalls opinions on this.

SexyTransAm

iTrader: (6)

LT5 /thread

shanemilleresp

its all about airflow man it has nothing to do with how many valves in fact the only cars that really use the 4 valve right are f1 cars. look at top fuel still one cam in the valley plus its less things for the motor to turn if you only have one cam, so unless you plan on going 15+k rpm go with a push rod. ls3 heads outflow any ford 4 valve head and ls7 heads make big blocks look like smog pumps. we get all the power we need out of one cam.

chuntington101

It comes more down to cost and fitment than what shanemilleresp said! There is NO DOUBT that a LS engine with a well designed 4vavle per cylinder head would not outflow what is currently on the market.

If you want a technical answer then flow is related to valve curtain area. you draw one big circle on a page. then draw as 2 or three smaller circle in the middle of the larger one. messure, or work out, the circumference of the one large and then the 2 or 3 smalelr onces and see what you get. you will get a higher number with the 2 or 3 smaller circles. larger ciurtin area will equal more flow at the valve. Obviously you need to ensure the HEAD is designed well. if the ports flow for **** thenyou can have a million valves and the head wont work!

Ford V8 heads are CRAP! end of story. however the Ford Duratec inline 4 heads are very good. as are hondas Vtech units. Audis run 5 valves per cylinder (3 intake and 2 exhaust) and these should flow even better (although not greatly). another advantage is valvetrain stability. you put alot less stress on the springs with a OHC setup as you are effectively removing the pushrods from the equation. This should mean you can run lower spring presure (thanks to having less weight (F=MA so less weight requires less force for any given rate of acceleration)) for any given RPM.

For some idea of the advantages of well designed and worked 4 valve heads then take a look at the ford Pinto engine Compeard to the ford Cosworth. both are 2.0ltr engine, the cossy was design as a turbo engine but can be converted to N/A. a full on race preped pinto (2 valves per cylinder) would make around 230-250bhp and would be totally undriveable. a Cossy running 4 valves per cylinder can push 300bhp and still have reasonable maners! by the way the above two engine share the same block and are a good comparioson to each other.

I think Nelson Racing Engines are looking to manufacture SBC 4 valve per cylinder heads. have a look on their site. they recon they could build a street SBC that could spin to 9000rpm! you try doing that with the cam in the block and not needing the valvetrain re-adjusting every 1000miles! lol

Do i think the LS engine should have 4 valves per cylinder? NO. lol i think aftermarket guys, like nelson racing, SHOULD build these heads and help pushthe limits of the LS engines even further. however GM should no take away the manjor advantages the LS engines have of compact size for the displacement, low weight, easy of maintenace, lower modding costs, etc, etc.

Chris.

chuntington101

any poppet style valve isnot the BEST solution. look into sleeve valves used on some WW2 engines. these where rpoven to flow ALOT more air than any poppet valves of the time. they had their own problems, like sealing, but did offer more power for any given engine size.

also look at the spring design. Why not run penumatic valve spring assisters? you could presurize them at higher rpm or even have a cam that has diffrent lobe profile liket eh Vtech guys run.

Chris.

i6overboard

iTrader: (3)

I definitely agree with your key points, the LS heads flow great numbers and the simplicity of the 2 valve pushrod design can still yeild great power numbers.

Like you said ppl should build these heads to unlock the greater potential of the motors.

It would still be cool to be able to get a LS crate motor that can turn almost 9,000

justin455

You do realize that in the grand scheme of things OHC and OHV were both around during the birth of internal combustion engines?
It's only been in the "recent" 30 years that people have been nuthugging imports and their use of OHC.

on2

iTrader: (4)

I'll take less moving parts and overall smaller package of the OHV, oh and lighter too.

jakes4321

iTrader: (7)

Give me pushrods!!!

$750 L98

iTrader: (7)

*fixed

jakes4321

iTrader: (7)

I actually say that all the time to my modular buddies

HSV-GTS-300

2012/2013 DOHC plans that were cancelled/shelved in late 2008.


LT5 was to replace LS3
6.2L DOHC
500HP @ 6500RPM
500lb-ft @ 4400RPM
Direct Injection
Displacement on Demand hardware
Cam Phaser
376 cu/in
11.0:1 C/R
11mm Intake valve lift
41mm Intake valves
Steel Crank.


LT6 was to replace LS7
6.2L DOHC
600HP @ 7500RPM
550lb-ft @ 5000RPM
Direct Injection
Cam Phaser
376 cu/in
11.0:1 C/R
13mm Intake valve lift
41mm Intake valves
Steel Crank.


LTC was to replace LS9
6.2L DOHC
700HP @ 6500RPM
700lb-ft @ 4400RPM
Direct Injection
Cam Phaser
376 cu/in
9.0:1 C/R
Supercharged + Intercooled
13mm Intake valve lift
41mm Intake valves
Steel Crank.

chuntington101

The 4 valve per cylinder SBC heads (cant remember the name of them) used psuhroads to drive the valves.......

It was supposed to be a more bolt on solution to driving the valves than trying to add a cam belts or chains.

Chris.

$750 L98

iTrader: (7)

http://www.araoengineering.com/

snake95

I love me some pushrod engines, and just because it's "old" does not make it primitive as in no longer effective. Not many people know that the development of the OHV engine with the camshaft in the middle of the block was an accident to begin with, well, not accident, but they did not intend to keep it in the middle of the block during the beginning engineering phases, but once they found it was effective, they decided to keep it around. Don't remember where I read that.

Ben99GT

LS3s don't outflow stock GT500 or Coyote heads, peak numbers or at any lift point you want to pick. Don't bother with Hyland's 25" graphs either, they are off. Stock GT500s flow a tick over 330 cfm out of the box at 28", Coyote heads are pushing 350 cfm at 28" by .472" lift. GT500s also outflow LS7s up to about .500" lift, and by a huge amount in the .100"-.300" range. The 03/04 4V heds (Cobra, Mach) outflow all the cathedral ports (243s included), doing ~270 cfm at 28" by ~.500" lift. The other part most people overlook about 4Vs, huge low-mid lift velocity over a large 2V arrangement.

The Ford 4Vs are doing that on a 3.552" and 3.63" bores, now imagine the same 4V head designed around a 4.06" or 4.125" bore (increased port volume, increased valve diameters, DOHC would also allow for TiVCT). Not sure why you guys turn up your noses at 4V for LSxs, do you have something against ~450-500 cfm capable heads that offer good low-end and perfect driveability?

ColossalCamaro

iTrader: (1)

For the record OHC has been around for a VERY long time. About 90 years. I'd say thats old tech too. Caddie pioneered it, by the way.

Any links to your info, HSV?

Ben99GT

jakes4321

iTrader: (7)

I just like to keep it simple, I was a ford guy back in the 5.0 days but I would not buy a sohc or dohc motor. Just not for me I like my simplicity plain and simple.


Why mess with what works????

ColossalCamaro

iTrader: (1)

Because it can be better. The Mod motors blow the old SBF out of the water.