70 TA

David NJ, what year LSx engine do you own?

GM was able to eliminate EGR starting in 2001. The LS engines qualify as a low emissions engines and also avoid the gas guzzler tax. The low emissions the LS engines achieve is not only because of cam timing, there is more to it.

Now anything regarding emissions and such are speculation at this point on the LS7 but I would think it will meet the low emmisions status. This stuff is important to GM IMO as is trying to meet the no gas guzzler status. (gas guzzling is ok by me by the way I dont give a **** )

These new heads according to GM are supposed to flow 43% more on the intake than the LS6 head therefore that puts them in the 350 cfm area conservatively.

I'd like to see some hard numbers on what some 4 valve heads are flowing and I'm talking factory stock heads. Not worked heads, we all know what the LS heads can flow when worked as well as C5R heads that flow around 400. Another thing people have to think about is that C5R heads have flowed 400 and change but at very high lifts like .750 the LS7 heads are supposed to do 350 at 600. This is more important to me personally.

A big cubic inch engine doesn't need variable timing since we dont worry about low speed torque. I though this was why variable timing came about for the sewing machines. This is just 1 reason why some of us like big V8's as opposed to farting around with 4 bangers.

The 2 valve / multivalve debate will continue to get beat to crap nothing I say here will stop it but one thing and only one thing matters and that is how fast is your car. Naturally aspirated right as of now nothing IMO beats the LS engine bang for buck. If there was I would be looking to put that in my car

Sure there are some exotics out there that produce a bit more HP but look at the cost.

Heck the only way Ford's 4V POS can beat the LS engine is with a blower.

I want to also mention what another poster mentioned several posts back. This engine is small and lightweight. It weighs less then some turbocharged multivalve 4 cylinder setups. Weight and packaging are very important to Auto makers for obvious reasons and to me also.

My question to anyone is what is more high tech. High $$$$ heavy multivalve setups that are crammed under a cars hood or a small compact lightweight package that does the same if not more and far more reliably with less moving parts and is able to meet federal low emission status and also beats the crap out of just about anything including some high $$$$ exotics.

Not trying to be smart or rude (maybe a bit humourous) so please no one take it that way

70 TA

Yeah and those heavily worked 4V heads still dont flow what worked LS lowly 2V heads do nevermind what the LS7 heads will.

5w20

iTrader: (21)

Look at the size of bores...That plays a huge role in what they can flow. 4"+ bores will work wonders. Now lets put a SBC head up against a BBC head.

70 TA

Your right a lot of this is apples to oranges but I though multivalves would make up for bore size and CI

Bigger bores do make more power for many reasons, thats engine power 101

All that matters is who's faster right?

5w20

iTrader: (21)

Ok lets compare some 'stock' casting Ford 5.0L heads or maybe some 3rd gen 350 TPI heads and see how much they flow. I bet those 2V heads flow significant amounts of air since they seem to loose power ~4500RPM.

I will be happy when my car is completed. I mean having a raceweight of ~2750lbs and 500+whp on (93 pump with no mix) is going to move quick I 'hope'.

To each his own, but saying that 4V heads can't flow.

70 TA

I have an 89 IROC with a TPI 350 LOL, it does run out at 4500RPM but I think this was due to the long runner design of the intake more than anything and besides the 80's was not a good time for performance as far as the big 3 were concerned. Thankfully technology has gotten ahead of the government mandated emissions and gas milage standards.


I am certainly not saying 4V heads can't flow. Not at all. Of course they flow well.

I am saying that the LS engines hold their own very well when comparing to multivalve setups and even boosted factory setups. Its a very well engineered engine and anyone bashing it needs to do a bit of research.

2750 lbs and 500+ RWHP, mind if I ask what it is?

Another_User

But why should we sit in the stone-age just because V8s have more cubes? Why not continue to make V8s that are even more efficient, and able to get better gas mileage? Less valvetrain parts and friction, and more efficient heads (two valves, multi-staged, would allow more torque and fuel economy down low, while producing more top end horsepower). I don't see the "lose" part of this 4v head arguement. It would only make sense to move forward like the rest of the auto makers. Not that GM makes sense very often...

It is only costly to make 4V heads because that is not what they are making most of now. It is just like anything else. You produce and sell more, the cost goes down. GM is just being cheap because they know the majority of their buyers are thinking like you right now. Just like with the stupid LS2, with the crappier (and cheaper to produce) intake. All they did was throw a few more cubic inches at the "cattle" and everyone ate it right up. Who cares if GM sacrificed 10hp here, 20 horsepower there?

LTSpeed

regorih - You're right about the 3.0L vs. 3.5L Hondas. However, they are 99% the same block. The crank is the difference (plus the mounting points for a few accessories). You could drop a 3.5L (or even a 3.7L) into an Accord right now, but the intake won't fit under the hood.

(Sorry for taking so long to respond. And sorry for potentially taking the thread off track).

70 TA

The lose part of 4V is the cost and the complexity.

I for one am very happy with a 2V pushrod engine that makes similar power #'s to more exotic multivalve engines.

Hey you guys that can afford it can hotrod Mercedes and BMW engines

GM builds cars for the average joe lets not forget that (and the Camarojoe )

Heck these POS GM cars are barely affordable for some of us now

5w20

iTrader: (21)

LTSpeed:

Yes they are about 90-95% percent the same engine. I was just pointing out that one is larger in cubes than the other.


CamaroJoe

Hey man i was never bashing the GenIII or GenIV style engines. They are awesome engines and have great potential. I know I'm going to be bashed for this but, my setup is going to be almost the same as the link that i provided with the civic. I own a civic with a integra swap. Only differences are I'm not going to use the stock 87.9MM (~3.46") stroke instead a 95MM (~3.74") Crower crank, Crower turbo cams stg. II, and an E-cutout on the downpipe. (he dynoed through the full exhaust)

Hey believe me I know 2V heads can flow, my buddy has a stock bottom end 302 fox body stang that runs 11.9X in the 1/4 on an X-cam 224/224 542/542. He is only on 3.73's w/a 5spd too.

If I was able to afford insurance on a LS1 i would have one, but the insurance, car note, and wanting mods is too much $$$ for me. I can't have something that is stock or with light boltons.

70 TA

Naw man I would never bash anyone for there choice of car to hotrod.

I might poke fun at you a bit though Just kidding

Good luck with your project

5w20

iTrader: (21)

Thanks man. Happy "hot rodding" to everyone.

PureWS6

My question is....if OHC and multi valves are so great....how come NASCAR and top fuel racers aren't using them? Give me my old school push rod motor any day of the week.

Another_User

You guys really are stubborn.

MrYenko

Because both of those race series are more afraid of change than any other organization on the face of the planet. Thats a REALLY poor comparison, sorry.

GM has proven that AS A PACKAGE, an OHV engine is more efficient, not in terms of fuel economy or power, but in terms of packaging, for a given horsepower level. Sure, they could build a 500hp 4.0L V8 with DOHC and variable valve timing, but the thing would wreak havoc under the hood, needing MUCH more engine bay real estate, it would use roundabout the same amount of fuel as the new LS7 does, AND would cost more. Sure, the amount of material needed in an engine doesnt change cost much, but the additional machining needed for a DOHC setup is huge. We're talking double the number of valves, and four times the number of camshafts, not to mention springs, rockers, etc etc. A DOHC engine of identical displacement probably does have a theoretical advantage over an OHV design, but in the real world, it is sometimes more efficient to use an older principle, because of outside constraints.

Had GM been building an engine to dominate engine dynos across the land, Im sure it would have been OHC. But since the thing has to go in a car, they went with a far more efficient platform.

slow67

iTrader: (2)

http://www.araoengineering.com/

How about the best of both worlds?

Big-DEN

If packaging is a concern - which it is on the Vette.

Say you can have a 4.0L V8 DOHC with VTEC OR the 5.7 9.214" deck
pushrod that you have now. They both take up about the same amount of underhood space.

Stroking and boring is possible.

Say your 4.0L V8 has a 3.3" bore but can go to 3.4" bore max... The 4.0L already has a 1.2" compression height and 3.5" of stroke. You can SQUEEZE
out 3.7" of stroke to take it to 4.4L max..

The 9.214" deck can be bored to ( sleeve ) 4.2" and stroked to 4.25" max for
a max of 471 cubic inches or 7.7L. Canted valves are allowable.

Which would have more potential?

Reason I did not use the 4.6L Ford is because it is physically larger than
the LS1 motor, and nearly the same size as a 460 ford big block.

Another_User

Eh, heck with it, let's go straight to these heads:
http://www.coatesengine.com/csrv.html

DavidNJ

Let's break it into 4 things:

4-valve: has more curtain area

OHC: less valve train mass, fewer port obstructions

DOHC: supports variable cam timing which allows EGR removal, increases mileage. broadens torque curve

Direct action: which really lightens the valve train.

It would seem, that in nearly all passenger car applications variable valve timing on a DOHC multi-valve engine is the way to go. Virtually every new passenger car engine falls in this category. All those VTECs are here. Passenger car motors.

It would seem, that on restricted and most unrestricted race engines, direct action DOHC multi-valve is the way to go. F1, CART, Indy Car, etc. plus Enzo, Carrera GT, etc. plus the Supra and Evo.

It would seem, that in most truck and some high performance applications, large displacement OHV configurations are they way to go. LS1 is here.

Everything has its place and its limits.

Note: both Ford and Chrysler had SOHC big blocks in the 60s.

Where does the

Big-DEN

OK so trade DOHC for 2.0 or 3.0L of displacement out of the LS1...

See what we are getting at.

Packing space, cubic inch potential, weight all have to be factored.

All of us know if you could put DOHC heads on an LS1 and VTEC power would
be enhanced some.

With that same packing space more than a Liter of displacement couldve been attained, plus with the DOHC head we made the engine too tall and raised center of gravity too much for our performance vehicle.s...