theoldchevyman

It has been more than year now, that talks about a 3valve per cyliner head for the LS1 and Gen IV V8 would be out from GM and nothing has happen, I hope GM was not giving us a bunch of bull.I sure would like here from anyone that has more information on it, are there filling about the subject.

niphilli

The patent has been applied for:

http://www.corvettels9.com/6505589.pdf

http://www.corvettels9.com/6505591.pdf

http://www.corvettels9.com/6505592.pdf

My thoughts on the single cam in block is pretty neat, looks like a lot of valvetrain mass, but pretty neat. The dual cam in block seems like kindof a waste (why not go OHC if you are going to that extent, but I dont know all of the detals/advantages at this point.

gollum

iTrader: (1)

WOW! Good Stuff.

Bill Reid

iTrader: (14)

Here's an old pic... I think I snagged it from here quite some time ago...

Bill

JZ'sTA

iTrader: (23)

Why is my only question.
With the LS7/L92 stuff out now we have heads flowing way past 350 cfm's, and flowing numbers that some big block heads which they could do.
Seeing that there are some 600+ RWHP cars out there NA with LS7 heads shows that the heads we have available are working.
Last I checked the 4V mustang head in the 03/04 Cobra WITH a supercharger makes less power stock then a 2002-2004 Z06.
I sure sure with enough R&D there could be some nice gains with a 3V head, but luckly the heads are what is holding back the LSx motors.

Bill Reid

iTrader: (14)

... who knows what GM truely intended this application for... more than likely trucks. Its obvious by the intake design the motor I posted, not to mention the accessory drive, looks like a direct transfer from current trucks. I would SPECULATE that the 3 valve setup was being developed along side the L92 and LS7 stuff. GM engineering staff, obviously, extended more life into the 2 valve setup by virtue of "rethinking" the intake port design... along with chamber efficiancy updates. We may or may not see a 3 valve setup. My bet is they will add 2 more cylinders before pushing that complex valvetrain into mass production... for trucks

Just IMO

Bill

Steve Bryant

iTrader: (1)

I do not believe that GM would be going to a three valve head design with up to two cam shafts just to cater to the performance crowd. I do believe that they would consider such a change if they believed that they could improve the efficiency (i.e. BHP/unit of fuel flow) and economy (MPG) for production engines (mainly trucks, but also cars).

In a high RPM environment like drag racing, the double push rod, double rocker arm arrangement is probably no where near as bullet-proof as our current LS series engines. However, when GM has to consider everything that they can do to improve Corporate Average Fuel Economy (CAFE) for their range of vehicles and for the specific models, this type of design change is worth their consideration. The GMT 900 series of new GM trucks will be especially scrutinized by buyers and critics of the industry over the next several years. Combustion chamber and valve arrangement designs that contribute toward efficiency and economy will be considered just like displacement on demand (DOD) has been considered and is now being implemented for the second time by GM (first time was by Cadillac division in the 1980's and it didn't work well).

The upper (second) cam improves the exhaust valve push rod geometry and it would allow variable intake/exhaust valve timing if desired. The lobe separation angle (LSA) could be spread for smoother idle or to flatten and extend the torque/power curves or narrowed to intensify power (like climbing a hill under heavy load with a truck). This LSA could be dynamically variable and controlled by the ECM/PCM.

Kenova

iTrader: (4)

Very well said Steve. We have to remember that these engines are designed for mass consuption first and foremost. The high performance useage that we are interested in is a mere after thought.
One question that I've seen asked and that really stands out in my mind is "Why not go to overhead cam(s)?". I believe GM wants to stay away from OHCs because of the size. Have you ever seen a Caddy Northstar engine in person? Those little buggers are f*****g huge. They are as wide and maybe wider than a BBC.
Push rods forever for this guy.
Ken

firefighter

Well also remember it was a major consideration in the early days to go to a mod motor. It was the buzz back in the late 80's early 90's and Ford went with it and I personally believe that they must regret it. How'd the story go two identical 'Vettes one Mod motor one push rod a bunch of GM execs and we got the LS1.

Steve Bryant

iTrader: (1)

Firefighter and Knova,
You are both right. If you read Chevy LS1/LS6 V-8s by Will Handzel, he describes how GM decided to stick with the pushrod design rather than a SOHC or DOHC engine. This is an excellent book that I would recommend to anyone interested in these engines. Chris Endres' book Chevy LS1/LS6 Performance is also good and I'd recommend it too. Chris' book was written first and he doesn't have as much of the inside "scoop" or details as Will's book. However, Will is the head of GM Performance Parts and had access to a lot more inside information. Both are excellent!

Steve

firefighter

I read Hadzel's book and yes it is a great book. Somebody needs to come out with a new book as so much has changed since then. To me that is the main advantage to the LSx's the packageing is small and light how many mod motors do you see getting stuffed in to Miata's and RX7's? The motor is small but put's out numbers comparable to old big blocks and the heads just keep getting beter.

blown4.6

03-04 cobras were underrated from the factory

The Butcher

I think just about every car owner thinks his/her car was "underrated from the factory" Fact is if anything they're probly all overrated. The only reason power was ever unerrated was back when car insurance was based on hp. Not only is that not the case today, but why would a company deliberatly talk down it's own car. Like I said, I wouldn't be surprised if all cars are overrated to an extent so that they sound more desirable.

distortion_69

iTrader: (20)

Some dyno higher than others.

The fact still remains 4v mod motors don't really seem to have any advantage having the extra valves. They don't really dyno higher .. displacement taken into consideration (hp/l). They also are heavier, larger, and don't seem to get any better fuel milage. It's hard to imagine a swap to 3 valve would net much performance gain.

Later,
Josh

blown4.6

the 4v heads on 03-04 mod motors if im not mistaken flow 325 cfm which isnt great but its not bad. (yes i know chevy does it with 2v's on the new ls7 heads)

chuntington101

guys please forget the ford motor! we all know its not the greatest 4valve per cyclider ford have ever done (by the way for are VERY good at 4valves per cylinder! takea look at the 4 cylinder Duratec! it has a head a F1 enginer would be proud of! lol).

now back on topic. with the LSx motors you have good displacment. now if you take that displacment and add valves then you get an even better engine!

look at the new Merc 6.3 ltr 32valve V8! now thats a nice motor. and a much better comparision to the LSx than the ford unit!

thanks CHris.

blown4.6

For some reason I can't see chevy switching due to added costs when they can already get great flow through current heads but who knows

theoldchevyman

As fare as the patents they were done in 2003,also back 2003 the information was the 3valve added 15% more power and a bunch of torque so i thank gm was developing the heads for the truck engines.but what is wrong with it also applying it to the up coming RWD Impala or the Camero base V8 and 3.9 V6 engines?

Cop Car

iTrader: (14)

there would be several advantages to a 3v head. 1 you get bigger exhaust valves, and between the 2 intakes valves you get more area also, more than if you had the traditional 2 valves. another advantage that i think im seeing is a hemisperical head. the dome shape is the most effecient and allows for the best entry/exit in and out of the heads, also allows for more lift to be had. the problem with in block cams and hemi heads is that the pushrods tradtionaly go every which way and look like a porcupine. with this set up, it looks like these heads would bolt onto any LSx motor and allow for anyone to use the hemi head and 3vs.

yeah the LS7 flows great, but its CNC ported which adds to expense, if they produced a 3v head that flowed 350cfm out of the box it would be freaking amazing.

8banger

iTrader: (16)

In a streetable context, with moderate (10.0:1 - 11.5:1 ish) compression, the LS seris motors, for the most part do better than the 4V's; however, in fully built/race setup, modular motors are impressive. A 304cid 4V with 12.x:1 compression and FR500 top end dynoed 470rwhp N/A, and VT Engines built some 5.4-based 4v"s that dynoed over 700rwhp N/A. That's over 2rwhp per cubic inch....sick. Not streetable but true nonetheless.

If you want to bring FI into the equation, a mostly stock 3V with a 3.75" crank and a Procharger F1 put down 770rwhp