DavidNJ

I am note a VTEC fan. If you want variable valve lift, the BMW route would be the way to go IMHO.

Street LS1/2/6/7s seem to be at 65-70hp/liter. DOHC is up to 120hp/liter, with may over 100 hp/liter. Even mild versions are at 85hp/liter. So you would need a 20-50 increase in displacement. Which is where the 427 LS7 is.

All that FI from Ford, MB, and GM is just another way of adding displacement. They are all superchargers, aren't they?

Bombguy99z28

Does Ford still have to run 4 cats on their Mustangs cause they can't make an emmisions friendly engine?

And who keeps bringing up EGR? The last LSx engine that had EGR was in 2000.

70 TA

I think I answered it all here https://ls1tech.com/forums/showpost....1&postcount=41 but it seems I was right no matter what I write it wont matter

Who gives a crap about HP/L anyway sheesh we had a couple hundred posts on that a while back too Isn't the absolute most HP what matters? The fastest car wins no matter whats under the hood.

Fine LSx engines are crap we give up

By the way Chevy had multivalve OHC Indy engines way long ago.

http://www.autointell-news.com/News-...r-18-02-p3.htm

http://www.sae.org/automag/techbriefs/03-2002/

http://www.superrod.com/News.asp?ArticleID=3

Yeah so WTF is that? Duh!!!!!!! No Gm cant make an OHC engine LOL.

I've got pics of experimental stuff from all the way back to the 60's.


Nice stable of cars you got there Bombguy, pretty similar to mine

chuntington101

man i love this! people really talking about what they love, and not getting into stupid arguments in the procces. i take my hat off to you all for being involved in a GREAT thread. a real good read.

now if you take 2 Honda inline fours and mate them in a narow angle V (say 15-30 degreas) and then mount 2 of these Vs onto a comon crank then you will have a W16 with 8 ltr!!!!!!!!!!!!!!!!!!!!

ok i hope VWA dont sew me as i have just nicked their idea hehe. but if you did it with 4 3cylinders then that would give you a 6ltr w12 that would be shoreter than a V8!

camaro, i dont think anyone is saying the LS engines are S**T, just that they could be better, like EVERYTHING. they are a great engine and i cant wait for the price of them to fall over here so us Brits can get our hands on a few. they would make great kit car engines as they are smaller then our Rover V8s and make a shed load more power!

thanks Chris.

ChucksZ06

iTrader: (9)

It is obvious non of you guys are plumbers or you would understand that a larger pipe flows a lot more water than a small pipe. My cobra has two holes entering the combustion chamber that are aprox 1" in diameter which gives you 1.58 sq.inches of cross section and each of these "tubes" has a valve stem in the way to impede the flow. My 2" tube in my chevy has 3.1 sq.inches of cross section with one valve stem in the middle of the large tube not 2 stems in 2 small areas. When you look at the two the ford ports look like a lawn mower engine. If you could get large valves like a hemispherical chamber does it would be different but then the size of the head gets huge. The curtain area of the valve is a red herring. It does not take into accout the size of the port under the valve. The seat width and valve stem diameter take up a much higher percentage of available flow area on a small valve as compared to a larger valve.

chuntington101

and thats why plumbers dont build engines! if you look over here at some of the engine that are used for raod/race/rally/sprint/hillclimb you will see that 4valves are definatly better than 2. here are some examples.

Ford pinto. 2.0ltr 8valve engine. race units with huge heads max power is about 240bhp. and thats as drivable as a rocket motor!
Ford Cosworth 2.0ltr 16valves converted to N/A. a half decent rally engine will see an easy 250bhp, and thats a lot less stressed (read lower revs) and a hell of a lot more drivable than the pinto.

Vauxhall (UK version of GM) 2.0ltr 8valve. again you are looking at about 200bhp, but no one uses them coz they use the..........................
Vauxhall 2.0 16valve XE or Ecotec engines (very similar, the newer Eco runs a difrent head on the same block). you can get an easy 200bhp with a set of bodies and a cam swap, and 250-60bhp with some head work and wilder cams. the racers run about 300bhp from the XE (at about 9K).

Honda. dont know of any recent 8 valvers, but do know of a few 16 vlave engines. standard trim the 1.6Vtec makes about 160bhp but in rally trim, rataining the stock inlet manifold, 240bhp!

then you get bike engines. dont know of any 2 valvers (apart from Harley) but i would love to see them try and recreat the power figures of the like of the Busa are producing. 1.5ltr strocker making over 250bhp @ about 10K. tell me im wrong.

now before you go on about the torque that these engines produce, you will find that the 16 vlave engines (in cars anyway) will have a slightly higher peak value but over the operating range they are much better, and far more drivable. and thats what 4 vlaves does, it opens up the breathing and allows better flow at higher rpm, thus making the power band wider. also this is better for FI as you are dealing with greater flow.

a bit of a side note. if GM where to go for a multi valve head i wonder what would happen to compaines like AFR???? i ask coz i dont think i have ever seen, read or heard of anyone (no matter what engine) swapping the heads with a multi valve engine! its easier and cheaper just to get a little port work and fit some bigger cams!

thanks Chris.

ChucksZ06

iTrader: (9)

all the engines you quote are small engines and they are as you say way down on torque. You are comparing apples to oranges. Just because a certain design displacing 3 liters makes 400 hp you cannot extrapolate that to a 6 liter that makes 800 hp. It drives me crazy you guys talk about gm not doing multivalve engines. The cadillac northstar has been around forever. Interestingly enough they are having to put a blower on it to get performance in the same range as the CtS V (Z0 6 engine).
Just like ford. Look at the rpms the bikes turn to get that horsepower...and how long would an auto enginel last at 10,000 rpms. The simplicity offsets the extra wt and complexty in larger engines. When you take this arguement from real world to theory about engines that do not exist then the arguement in not relevant. If you look at the europeans who build some larger multivalve engines you will see that they are only about the same in power to the ls 1s and most get poorer gas mileage. I would like to see the friction losses for a 4 valve head versus a pushrod of the same displacement?

LTSpeed

Just a caution when talking about multivalve arrangements and pushrods. Just because you have more than two valves doesn't necessarily mean OHC. There are multivalve pushrod engines out there.

And don't get too hung up on volume or flow numbers either. Velocity and turbulence (or lack thereof) are very important also. That's why the length of the intake runners and the use of LT exhaust is so effective.

This is a lot more complex than the piping under a sink.

DavidNJ

LTSpeed took the words out of my mouth. Except for the part that broke it into different features earlier.

For an apples to apples comparison of small motors, you would need to compare a 1.4 or 1.6 4-valve to a 2.0 pushrod. And you would be at the same power level in both.

What the LSx advocates (there is one in my Yukon 2500 XL tow vehicle and I have a C6Z deposit) are saying is that there is a tradeoff between packaging and breathing. The LSx performs with displacement. The others with breathing. And they get to the same place. The current level of LSx heads and intakes, coupled with the all aluminum motor with the 6-bolt mains, makes that a good tradeoff.

Evidence is the elaborate 5L V10 BMW or 4.3L flat crank Ferrari. Similar peak power (a little less with the Ferrari), however a much narrower powerband. And expensive as all getup.

If we added the Harrop 8-butterfly intake (both the BMW and Ferrari have individual cylinder butterflys) and maybe a flat crank (or 180 deg header), I wonder were the LSx would end up. And for performance, remember we can fit 457 cubes, a solid 7.4L, into that package with minimal weight increase.

David

chuntington101

David. again 2.0ltr race Pinto produces 240bhp (and thats the best engine in the world tried and tested for over 20 years!!!!!!!!!!). QEDs 1.6 Vauxhall Ecotec race engine (that was still driveable and pulled like a train for a 1.6) 250bhp out the box with little testing! and why should you have to compare a 2.0 8 vlave to a 1.6 16valve? why can't i compare it to the new Cyclone 2.0 V8? which by the way make 300bhp + out the box on carbs and makes over 200lbsft of torque!

i think alot of you gues are moving the goal posts to suit you. in my mind you compare like for like, 2.0 vs 2.0, 5.0 vs 5.0. i have no problem with the LSx (wish i got a tena every time i said that), but i have groven up wherre engineering is always being pushed, and not just in a performance dicrestion. you see if i where in charge of the engine side at GM, i would already have a 4 valve per cylinder lsx engie built (if not in a car) and i would be looking into pneumatics as well. and you guys keep mentioning packaging, which is a good point. but what if you mountedthe cams at the side of the head and drove the valves with a rocker of the "inverted" cams. this would reduce the hight of the head. OK so the head would be wide and the intake would be interesting but as honda's addvertising campain keeps telling me "what if"..............

thanks Chris.

David the BMW and Ferrari engiens are sooooo nice though. a 3.6ltr flat plane crank V8 at 8000rpm does sound good.

Chuck, you will find that the rotaing mass of a OHC engine will be more, but the total mass of the moving parts in a push rod is more. hence why you need stronger springs. and the friction losers will be higher to, just look at the number of contact points (cam to follower, pushrod to rocker, rocker to valve caompaerd to cam to lifter, lifter to valve).

Big-DEN

Look @ packaging and weight. And if you decided to do DOHC on the LS1 the motor would be physically bigger than a big block.

Some of the DOHC have "rockers"...

Intake tract is similar to plumbing and most theories on intake and exhaust design
came from study of physics and fluid dynamics.

ChucksZ06

iTrader: (9)

great input...I am working on my 4 valve cobra motor at the same time I am building an ls2 403 cu.in. I am not saying that the 4.6 ford is the greatest multivalve ohc engine but when you compare the two it is obvious that a highly refined pushrod engine has a lot going for it. The blower intake assembley on my cobra weighs almost as much as the bare ls block, thecylinder heads are 2 times as heavy as the ls heads and they sit up high on the block which kills cornering performance. I have actually considered putting an ls engine in my cobra with custom fold logos on covers so I could run at ford events...it would improve the handling of the car like nothing I could do short of an all aluminum for small block. Oh and by the way my ford blew its head gaskets cause 15 lbs boost at road races was too much for it. But without boost the heavy car is not fast enough. I just cannot get past the genius of the simpler (smarter) machine compared to the overly complicated machine. My 403 should have about 500 to 540 rwhp. My cobra has 503 rwhp. I would love to have my cobra with 250 lbs less on front end with equal or more reliable hp. You have to get past the theorizing and talk about what works...Talk to people that race small displacement boosted multivalve engines and they are not long lasting engines. They might prove to make more horsepower but at what practicality level. Thanks for the mention of the fluid dynamics. If we think of air as a liquid we can understand better what is going on in our ports.

DavidNJ

Chris, the issue is packaging. The Pinto is a SOHC, isn't it. I raced one stock (SCCA showroom stock sedan, on 165-13 tires) when Pintos were new.

The LSx (and the Viper V-10) are truck motors adapted for high performance cars. And they work well. With its compact dimensions and all aluminum block, it is very interesting. In the trucks, displacement rules. Compare these engines to the lackluster OHC engines in the Ford trucks.

The reason we can't be more specific is we (at least I) don't have external dimensions and weight for all these different engines.

Last, there are 4 things here: multi-valves, OHC, DOHC, and direct action. They are independent (except that direct action requires OHC unless your running a flat head). You can have a direct action OHC 2-valve. You can have a 4-valve pushrod motor (with one pushrod operating 2-valves). You can have a DOHC 2-valve engine (as most were until recent years, including my--sold long ago--'68 Elan S4).

The BMW, Ferrari, Evo, and Supra are all 4-valve DOHC direct action motors, although I think only the BMW uses variable valve timing, the chief advantage of DOHC IMHO.

David

P.S.
I also have a '94 Supra TT.