Scissors

And what are the Ford engines' HP/pound or HP/cubic inch of engine size (not to be confused with displacement)? I bet the Ford engines are far heavier and larger than the Chevy engines per HP and per torque area.

That's the thing. If you throw either of the Ford engines in the Corvette you'll get better 1/4 times and worse track times. The engines are heavy and large, putting the Corvettes center of gravity further forward and higher. Meanwhile the Chevy LSx engines are about the same weight as a Mazda rotary engine.


[Modified by Scissors, 9:25 PM 1/18/2004]

SWCDuke

Isn't that stretching it a bit? I've not seen a weight spec for a Mazda rotary, but they are light and tiny, and and I don't think any reciprocating automotive engine can compete with them in terms of output per pound or cubic foot of engine volume (but they have poor fuel consumption.)

I recall seeing a "dressed weight" spec for the LS1 (inlet and exhaust manifolds, all accessories - alternator, a/c compressor, p/s pump and drive belt) with an auto trans flex plate and it was about 500 pounds.

I can't imagine that a rotary is much more than my Cosworth Vega engine, which is a little over 300 pounds, with only an alternator and 18 lb. flywheel.

Duke

I Bin Therbefor

I believe if you take the complete weight of a RX-7 twin turbo with all the intercooling stuff, you get very close to the weight of a Gen III. :cool:

SWCDuke

Yeah if you include all the turbo hardware from the TT it would add up, and that's probably fair because the naturally aspirated rotarys don't have anywhere Corvette type power, but the 12B and 13B engines in the first generation RX7 looked like you could just reach into the engine compartment and lift them out with your hands.

Duke

Scissors

There was a thread somewhere in which an RX-7 rotary engine's weight and an LS1's weight were compared. the LS1 was around 20-30 lbs. heavier.

Edit: And, yes, I believe it was the turbo engine. After all, if you're comparing weight and power, it's best to get one of them to be close to the other. ;)


[Modified by Scissors, 9:52 AM 1/19/2004]

LTC Z06

If all you care about is cheap RWHP and drag racing then a mustang is the way to go.

Duke I've been arguing on this forum from the git go that pushrods do not mean old tech, nor to double overhead cam etc. equal high tech, but I think the ***/German advertising has taken it's toll and it seems a lost cause.

Jimwood

What does cheap RWHP have to do with the advancement of engine technology. Seems to me the more hp you can get with less cost shows advancement, as significant modifications do not need to be made.

Does less HP=More advancement?

The rustang engine is probably poorly constructed but, this discussion is not about engine quality its about engine technology. If the rustang engine was made out of the same materials it would be better, Im sure.




[Modified by Jimwood, 12:41 AM 1/20/2004]

SWCDuke

Yeah, there are a few guys who understand, but most don't get it. That's why I started the thread.

It ain't a lost cause until the enemy kills you. ;)

Duke

WhiteDiamond

Since the Corvette is doing most of that killing, on the street and track anyway, I think the enemy has a long ways to go. If your predictions on the new LS7 coming( which seem to be supported by another member ) in a new Z06 are true, the enemy may get set back a few hundred years :cheers: I guess I just don't understand what is wrong with pushrods and what the big hype over overhead cams is. Oh well, both seem to have their place and, when properly used, have excellent results in there own right.

Todd

LongTimer

:chevy = torquemonster

need-for-speed

any engineer worth a damn knows that the simplest, cheapest solution is the best, as long as reliability and functionality are not sacrificed, which in the case of the LSx motors, is not. In fact the torque bandwidth as pointed out by SWC, shows the LSx to be a SUPERIOR solution. But alas, you (and GMPT)are competing with some very clever advertising / marketing and movies like the Fast and Furious.

Scissors

F&F taught me that having your floor pan fall off is a very serious and common problem for those who use nitrous.

LTC Z06

Same materials? Is GM's steel and aluminum better than Ford's I don't think so, the engine is fine, nothing wrong with it really. I really don't understand the point you are trying to make :confused:

First go read some engineering history, the double overhead cam, 4 valves and a supercharger were on the 1930s Dusenburgs, and the push rod V-8 was the holy grail of engineering because it would be more compact and less complicated. Other than computer control, the only real new advancements out there are the various variables, like variable camshafts, intakes, exhausts, and now from Saab displacement! And the only reason those German and *** engineers are forced to come up with these advances is because their engine displacements are taxed so heavily, if they had cheap gas and low taxes they would have the same engines that we do :yesnod:


[Modified by CPT Z06, 10:47 PM 1/20/2004]


[Modified by CPT Z06, 10:51 PM 1/20/2004]

99C5Vert

I don't know why this turned into a Ford / GM thing, but in terms of h/liter, the LSx engines are not what I call state of the art. Take a look at M3 engines, any of the high performance Honda engines, and a whole bunch of others who are squeezing out 100 hp/liter... by that standard, LS2 would have to produce 600 hp, normally aspirated.

Before the flames start, I know those other engines rev higher, but the difference is too great to ignore.

Having said that, there is alot more to an engine that hp/l. driveability, area under the curve, NVH, fuel efficiency, emissions and weight all factor into it. I'm happy with the compromises GM has made to make these engines a complete package.

Jimwood

That aluminum vs. cast iron comment was addressed at the lower weight and center of gravity comment that was made to show how the GM engine was more advanced. The block of the C6 per MT is alum, whereas the block of the S/C 4.6 is cast iron. Im not going to explain the weight differences.

Also, I supposed I hijacked this thread a little bit. Sure GM has made excellent advances on old technology. To that extend you are correct. To the extent GM is advanced technology, I would have to disagree. Its just like improving the steam engine, its still a steam engine at the end of the day.

Just a comparison of HP output per Lt.

400HP out of 6L V8 (66.6 Hp per Lt.), is just not terribly impressive in 2005.
330hp out of 7.4(44.6 HP per Lt.) stock carb V8, Mercruiser in 1980.
410hp out of 4.6 (89.1 HP per Lt.) (Im not using Fords underated estimate)
By the way the reason I use HP is because that was your rationale for demonstrating the advancement.

And CPT :flag
Dont you think that advances with DOHC show better advances then with the pushrod. Hell even GM thought that was the best and made the LT5 :eek:

I havent seen your advanced pushrod technology beat any of the LT5 endurance records yet. :eek:

Whats your point again? SOHC, DOHC has made more advances then pushrod.

The argument that DOHC, SOHC came out before the pushrod doesnt mean anything when you are talking about engine advancement. As the pushrod is such recent new and god sent technology, then according to your reasoning it should be leaps and bounds farther then SOHC, DOHC, but its not.

Trust me I have looked at this throughly. Oh I forgot the 4.6 S/C has much more torque also all the way across the powerband.

The only legitimate argument I have read yet, is that technically a S/C is considered more displacement, at sanctioned racing.

The reason the C6 still uses pushrod is because old tech is cheaper to improve then replace outright. Improvement only means advancement in a vacuum. If you look at other engine designs currently out there the pushrod is outdated based on its HP and TQ numbers per litter.


:cheers:




[Modified by Jimwood, 6:40 AM 1/21/2004]

LTC Z06

Jim I'll just say this, you need to read "Corvette From The Inside" by Dave McLellan to understand WHY they made the LT-5 and that will help explain this last line of my last post:And the only reason those German and *** engineers are forced to come up with these advances is because their engine displacements are taxed so heavily, if they had cheap gas and low taxes they would have the same engines that we do.

Also, you should count your SC displacement in a HP/Liter ratio. After I would pass a Porsche at a track I never had one of them walk up to me and say "Well at least I have variable valve timing" :lolg:

SteveJ

A lot of this discussion is based on reality, which is not what appeals to the people who buy Porsches or Ferraris. It's kind of like telling a Rolex owner that your Timex keeps better time and is 1/100 the cost. When you get to the point in life where you stop trying to impress people and can base a purchase decision on true value, it's amazing how much money and inconvenience you save. Take a look at some of the Porsche boards and do a search on RMS (rear main seal) and see what you come up with. :lol:

Matt Gruber

:jester
a man only 3 feet tall can build a house with 4' ceilings and get twice as many rooms :jester
(hp/liter argument) :rofl:

Jimwood

:iagree:
Now, stop making it in favor of the LS2. :lolg:


[Modified by Jimwood, 3:16 PM 1/21/2004]

COBrien

It seems to me we're actually talking about two different things here. On the one hand there's discussion of whether OHC or OHV technology is superior; at the same time we're comparing a SC engine to a NA engine. These in fact really have nothing to do with each other; you could just as easily compare a SC OHV engine to a NA SOHC/DOHC engine, and in that case the hp/liter stats would be slanted the other way.

No doubt the SC 4.6 is a great motor, but its hp/liter output is due far more to the SC than to OHC technology.

There are drawbacks and benefits to both OHV and OHC, but to compare the two you need to talk about them in the same context - two engines with the same displacement, both either with FI or not, etc. Only then can you really compare the TECHNOLOGY of OHV vs. OHC.

On the other hand, if you just want to compare the 4.6 SC engine to LS1, etc., then obviously that's a different matter. But that argument does nothing to prove the advantage of OHC vs. OHV. It's simply a comparison of two different motors.


[Modified by COBrien, 9:24 AM 1/21/2004]