VietRacingGuy

wow, that is alot of opinion. thanks.
well, i found out about the valves and cam stuff along time ago when i decide to get me a camaro z28. i made a lot of research to see which car has the best performance that my dollars can get.
camaro z28 LS1 has less power than twin turbo supra. but if i put a supercharger or turbo in this LS1 monster, it could have more than 500 HP with stock displacement
LS1 is a big engine 5.7 liter. so i think it is made up for what it does not have. toyota 8 cylinder engine in the new 2005 supra produce 350 HP, and it is only 4.0 liter, but with twin cam and dual valves,
to me, GMC is the best in making V8. my second favorite is toyota. i dont like honda b/c they love to put Type R sticker on their slow cars.
and one more thing Aluminum is not a good heat conductor like iron, but it is lighter, about half when compare to iron.

roger

the ZR1 made awesome power for the time.if the same engine was in production today it would make more power than the ls series engines.gm dropped it because of cost,not becouse it wouldnt make power.

dohc and multi valve setups have more potential for power,doesnt take a genius to figure that out.

the ford 32v engine is just to small.if dicplacement was up it would do better.

GM was smart in building a large displacement engine,it can make up for alot of technology.

Colonel

"but if i put a supercharger or turbo in this LS1 monster, it could have more than 500 HP with stock displacement"

You could do ALOT better than 500 RWHP. 800 RWHP or more is certainly possible.

Cheatin' Chad

iTrader: (3)

What it comes down to is there are many different ways to make power. Four valaves per cylinder are in fact superior to two in your typical internal combustion engine as far as ultimate power production goes. There is no denying this. Simple math shows that you can get more valve area this way.

Seriously, Who is really looking for ultimate power in a street oriented engine? VERY few people are looking to push four figure power numbers on the street. Increased cubic inches and maximizing the flow characteristics of a two valve head can make you more power than 99% of the people in the world can handle on the street.DO not forget the fact that forced induction is a viable option on a well designed two valve IC motor.

It seems to me you have (unfortunately) gotten caught up in marketing hype. You do not need four valves and overhead cams to make power.Would a four valve,variable timing LS based motor make more power than the current model? Without question it would.It would also add to the cost of the motor and increase the amount of parts in the engine which would theoretically make it more unreliable.There are MANY people on this web forum alone that are making over 500RWHP with their two valve,non-variable valvetrain engines.

Cheatin' Chad

iTrader: (3)

I agree with OHC being no more or less technology advanced than pushrod technology. They were making OHC motors in the 20's.

One way to make a "large displacement" engine rev reliably in the 9k range is to use more pistons. Ferrari has a 5.xl V-12 that will rev to the stratosphere. But look at the cost...

Old SStroker

The closest thing to a 32 valve LS1 I've seen from GM is the V16 they built for the SIXTEEN show car last year. My guess is we'll see those 32 valves before we see a 4 valve/cylinder LS1 derivative from the General!

The head design is very much like an LS1 with 2 valves per cylinder. It is 830 cubes with over 1000 hp achieved on the dyno. Over 600 lb-ft at half throttle and 2400 rpm if I recall.

roger

trust me it wont be to long until we see GM using 4 valve per cylinder v-8's.

some of the reason companies use tem is for emissions.a smaller bore creates less emissions and the only way to maintain good flow thru a small bore is by adding valve area.

look at the modular ford.stock for stock they maintain more flow at all points of lift thru a bore that is just 3.55 compared to the ls1 that is 3.9 or so.

Old SStroker

[QUOTE=roger]trust me it wont be to long until we see GM using 4 valve per cylinder v-8's.

QUOTE]

No quarrel there. The 32V Northstar V8 has been in continuous production since '93. The newest version for longitudinal applications (SVX and XLR) has VVT on inlet and exhaust. Pontiac is to get the 4.6L Northstar in the GXP later this year. The Aurora used the 4.0 L version, and the early IRL engines were based on it.

I just don't believe you'll see 4-valve V8s in regular GM trucks in the forseeable future. LS1/LS2/LS6 are primarily truck engines, with the truck volume paying for the R&D and tooling to have them in Vette, CTSV GTO, etc.

rotarnomore

iTrader: (1)

It is also a fact that four valves per cylinder offer better efficiency with air intake hence better opportunity for better fuel economy. DOHC engines also benefit from having an independant exhaust cam and intake cam which can be set independantly of one another (you could advance the intake and leave the exhaust alone with grinding a whole new cam). over head cams do not need to be as radical (with fast ramp rates or lifts) to achieve the same effect. The can also (generally) achieve higher rpms since there are no pushrods that flex, less "play" in the system, etc. Also, compare a 5.7 over head cam to a 5.7 pushrod. It is a fact that over head cams are more effiecient engines. the draw back is they cost more to manufacture. I think where chevy has really done there homework is lighter parts in particular to the all aluminum engine. But then again, it's a fact that an aluminum is not as reliable as an iron block. The LS1 is a good engine with benefits and drawbacks just like every other engine.
Chris

Old SStroker

Interesting thoughts, Chris. I don't agree with all of them, especially for medium performance street trucks, which are probably the majority of OEM engines built in this country. Actually in durability testing, modern aluminum blocks and heads are as reliable as iron. The very first LS1 truck heads were to be iron because the "truck heads" @ GM figured tht cast iron heads would last longer. Powertrain folks said aluminum was actually better, but it took some long durability testing to convince the truck folks. All are aluminum now.

As far as extreme performance engines, remember that power is a function of torque and rpm where it is produced and IC engines are basically air pumps. One way to rate airflow efficiency might be the torque per liter at horsepower peak. Probably the most highly developed NA engines which run for a period of time (over a million revs) before they are rebuilt are the 19,000 rpm 3.0L F1 engines and 9,300 rpm 5.86L NASCAR Nextel Cup engines. I suggest that they are fairly equivalent air pumps despite pushrods and 2 valve/cyl on the Cup engine and OHCs and 4 (or more?) valves/cyl on the F1. How so?

BMW claimed 900+ hp for their 2003 F1 engine and 19,200 max rpm. If you assume a Cup engine is about 800 hp, and also assume that hp peak occurs at about 95% of max rpm for both, which is probably close, you get some interesting numbers:

The F1 engine has about 82 lb-ft per L @ 18,200 rpm and the Cup engine has about 81 lb-ft per L @ 8,800 rpm! Both burn gasoline, are NA and have about the same average piston speeds. BMW published their p/s and with Cup max bore size, you can back into the piston speed if you assume the telemetry of engine rpm is accurate.

Perhaps pushrod 2-valve engines obsolence isn't here yet.

My highly opinionated $.02.

CHRISPY

I heard rumors of a three valve per cylinder Z-06. Still no overhead cams though.

roger

not to say that ohv is completely outdated,trust me i love pushrod engines.up until recently i have always owneda pushrod engine,and some that made some very respectable numbers.

there is something to say about drivability and smootheness also.generaly you can get away with 10 to 15 degrees less duration in similar setups with the dohc type engine with the same power output.its freaky on the mod motors that a cam with 215 degrees duration is considered big.

example on fords performance cams for the 4.6 usually generate between 350 and 370rwhp on a n/a setup.the cams on this setup measure 204 at .050.also generally the smoothness on the mod ford and the northstar engines is very noticable compared to the ohv engines.i work at a dealership with both ford and gm,s so this is by experience.

rotarnomore

iTrader: (1)

i understand what you are saying but race engines are an entirely different ballgame. Both engines you mention have restrictions put on them to limit HP. NASCAR engines in particular are carburated, octane limited, etc. F1 engines also have restrictions to limit HP but they do get to go buckwild with a lil nitromethane I still think every engine has its place in the right application. For me, I'm in the middle of plopping an Ls1 motor in my rx7. I chose the LS1 for weight, overall dimensions, and ease of upgrade (alot cheaper to just replace one cam). I haven't found a good use for the rotary engine yet but theoretically, it looks like it would make a good water pump. It just didn't work well as a motor for me and I don't have a need for a water pump.
Chris

Cal

iTrader: (1)

This is what I heard also. There will be one rocker arm actuating two valves. GM is going to this because they will need to get the Z06 up to 500 hp to run with the competition. The good thing is the new hardware will probably trickle down to us as upgrade parts. But as several others stated, more than two valves is overkill if you're willing to go to a forced induction system or bigger displacement to get more power.

Cal

iTrader: (1)

This is true; my RC helicopter has a 0.61 CID engine that runs at 17,000 to 18,000 rpm most of the time while I'm flying. It idles at 2500 rpm. It has a 21,000 rpm redline and produces 2.5 hp on methanol fuel that is 30 % nitromethane. That's 4.17 hp/cube; I wish my LS1 could do that! That would be over 1400 hp, but that fuel isn't cheap at $25 a gallon!

Old SStroker

Actually Cup engines are not limited much by octane, nor very much by being carbureted. Even a tad more compression ratio wouldn't help them much. Sure NASCAR limits them to 2 valves, pushrods and flat tappets, but my point was that that doesn't stop them from getting highly efficient engines.

F1 engines have even fewer limits: gasoline, displacement and some limits on exotic materials which can be used. In fact, F1 is designed to be "state of the art" almost no holds barred engines. Nope, they don't use nitro either. While their "gasoline" is far from pump 91, they are restricted as to what compounds they can put into it. Oxygen-releasing compounds are a no-no. Basically it's still high octane petrol.

F1 is seriously talking of limiting horsepower...by dropping the displacement to 2.4 or 2.5 L from 3.0 L, but not by design restrictions.

Name a NA, gasoline automobile "endurance" engine with more specific output (over 300 hp/L for F1) or the torque/L @ hp peak I mentioned, than Cup or F1 engines. You have go blow or use other power adders to beat them.

I guess we see things from different angles, huh?

2001CamaroGuy

iTrader: (6)

your reasoning behind twin cam OHC vs. OHV engines (which makes more power) is to compare a twin turbo car who’s engine comes with all forged internals and costs far more to a Z28

OHC has the advantage of less valve train parts (less mass, flex, things the bend/brake, etc...) but the heads are usually optimized for higher RPM applications and as such tend to be lacking when it comes to street performance.

OHV tends to be lighter, more compact, and the heads tend to perform better on the street. They tend to run out of flow (and run into valve train stability) at high RPMs (your 9000+ RPM Honda RPM ) but due to the larger cubic inches that they are used with, they rarely need to be run past 6500.


put down the crack pipe and go back to science 101

Aluminum is a MUCH better conductor of head than iron. Aluminum motors run cooler than iron versions.

Ever heard of air cooled engines (from your above automotive aptitude, you probubly have no idea what I'm talking about )?




This is almost (not sure if its better) than the guy that came on here a few weeks ago and said "I HEARD A CAMMED CAMARO AND IT WAS SO COOL!!!!!!!! I WANT THE COOLEST SOUNDING CAM I CAN GET!!!!!!!!"

Old SStroker

Specific output (HP per cube) goes pretty much with rpm. F1 900 hp @ 18,000 3.0L (183 cubes) is 4.92 hp/cube at just about the same rpm as your little 10 cc mill, but without the nitro!

Cup 800 hp 358 cube is about 2.23 hp/cube at less than half the rpm.

Hp/Cubes (as installed) in NA production engines are interesting:

Honda 2.0 L DOHC VTEC 2.05 hp/cube @ 8500 (S2000)
BMW 3.2L DOHC VVT I-6 1.71 hp/cube @ 7900 (M3)
Audi 4.2L DOHC VVT V8 1.32 hp/cube @7000 (Audi S4)
Honda 3.0L DOHC VTEC V-6 1.31 hp/cube @6250 (Accord 6-sp)
Nissan 3.5 L DOHC VVT V-6 1.22 hp/cube @ 6000 (G35 sedan)
GM 5.7 L pushrod LS-6 V-8 1.17 hp/L @ 6000 (Z06)
GM 4.6L DOHC VVT V8 1.14 hp/cube @ 6400 (Cadillac XLR)
GM 4.2 L VET I-6 1.07 hp/cube @ 6000 (Trailblazer, etc)
DC 5.7 Hemi V-8 pushrod .99 hp/cube @ 5400 (Dodge Ram)

Except for the 4.6 Cad, specific output pretty much follows rpm.

gojo

iTrader: (12)

http://www.z06vette.com/gallery/data/500/35c6head2.jpg

Hope this link works.

1CAMWNDR

iTrader: (21)

I would agree with almost everything so far. I wonder how the Ford OHC and DOHC V8s would run if they had a better bottom end design (Larger Bore with a shorter Stroke and longer Connecting Rods)? The small bore, long stroke, fairly short rods is what keeps the motors from reving. I am still shocked that their 4 valve motors have a 6,500 rpm red line and the 2 valve motors run out of revs at 6,000. How is that better than the Larger Cubic Inch, more Torque, more Horsepower, LSx motors????? That is right. It's not.