(standard version) GM's 5.7 Liter 350ci V8 (pushrod) 245hp@ 5000rpm with 330ftlbs. tq@ 2400 rpm

(standard version) Dodge's 5.7 Liter 345ci "Hemi" V8 (pushrod) 345hp@ 5600rpm with 375ftlbs tq@ 4400rpm

Thats 100 more horsepower. Sounds like a "significant" number to me?

 

Uhm, the modern 5.7L version of GM's motor is far more than 245hp. Either you're lying or you don't know. The 4.8L GM in my '99 makes 275hp. Go to GMC's web site if you don't believe me.

BTW, the newer GM motor has a hemispherical swirling design in the head. They just don't call it a hemi. The LS6 in the Z06 'vette makes over 400hp at 5.7L.

Regarding single bore engines - over 333cc, a cylinder loses thermal efficiency (well, that seems to be the general consensus of the ideal cylinder bore size). Bigger bores do make slightly more torque at lower RPMs, but because of thermal efficiency a bigger bore motor will not make as much power as two pistons displacing the same. Take V-twin motorcycle engines for instance, Ducati's most powerful motor makes under 140hp while the latest Japanese litre bikes all make over 170hp without the fancy solid-activiation valve system, and are much cheaper to produce (or buy). The more cylinders, the less flywheel affect you generally need, too.

 

I am quite aware that the newer GM motors do make more horsepower that before. I was comparing the STANDARD GM 5.7 vs. the STANDARD Dodge 5.7. Im am not talking about the hoped up LT1, LT4, LS1, LS4, or LS6 that you find in the Vetts, Camaros, Firebirds, ect. I am talking about the standard 5.7 that you would find in the Silverado (before they switched to the 4.8, 5.3, and 6.0 in the 99 and newer trucks) and other GM verhicals. Such as the 98 Chevrolet Express conversion van that we own. And it does have the MPFI 5.7 liter 350ci V8 in it htta is rated at 245hp according to the owners manual. As far as I know, GM no longer put the 5.7 in their truck, full size vehical lines after '99. That's what I was comparing

 

Come on Jason, you know better then to compare a new engine to one made over 6 years ago.

 

Same basic principles right? Approx same displacement, OHV, pushrods, one camshaft, V8? Take the GM 6.0 then. It is somewhere around the 300hp range right? That is a relatively new engine. Uses the coil-on-plug ignition system like the new Hemi does. And it is still less horsepower. The point I am trying to make is that the Hemispherical head design is a power proven very effcient combustion chanmber design. And before you guys jump on me for being a "chevy hater", I must remind you that I own a chevy. And I must say that my little 4.3 Vortech motor has taken a lot of abuse from me and has never left me stranded on the side of the road. The rest of the rig may be falling apart, but it is a good motor. I will also add, that Ford had their own version of the Hemi in the late 60's. The Boss 429 used a Hemi design head after seeing how good the chrysler Hemis were. I believe that Duesenburg (SP?) also used a Hemi design. And why do you think that just about all the top fuel drag racers use Hemi heads on their cars? That has to tell you something righ there

 

Uhm, OK.

GET THE FRICKIN' FACTS, PLEASE.

You're spouting off fantasy numbers for GM. And you don't appear to know that since 1998, GM's truck engines are LS1-derived. They're essentially LS1s with iron blocks and a cam designed for more lower end and midrange power. That's right, you have to buy an engine like you're describing in the crate now - you can't buy one in a truck OR car. For six years now!

AGAIN, GET THE FRICKIN' FACTS, PLEASE. Or I will make fun of you. [img]i/expressions/face-icon-small-smile.gif[/img]

(GM's 6.0L is 325hp/365tq with 13mpg city, 18mpg highway)
(GM's 5.3L is 295hp/330tq with 16mpg city, 19mpg highway)
(GM's 4.8L is 285hp/295tq with 17mpg city, 20mpg highway)
(Dodge's 5.7 is 345hp/375tq but lists no milage... which I'm told is horrible)

 

So are you telling me that the owners manual that was provided by GM for our van is incorrect? OK then. Im worng and so are the people at GM with their "fantasy" information that they provided in the owners manual. Whatever floats your boat. And are you telling me that they have not been putting LS1's in GM cars for 6 years??? I know that they ditched the 350 for the trucks in '99 when they switched body styles, but as far as I knew, the camaros and Firebirds/Transams still has the LS1 up until '03 when they were discontinued. Could you be more clear please? And AGAIN LIKE I ALREADY STATED!!! I was only trying to show that the Hemi design is mor eeffcient. You guys are jumping all over me because I may be off by a few horsepower on my engines, or am not using one of GM's performace engines for my comparison. Give me a fricken break!!!

 

No, give *US* a frickin' break. You were giving out incorrect and unsubstantiated information. I also said LS1-DERIVED engines. That's still true.

Go to the GMC web site. http://www.gmc.com/

It's not that hard. Public school kids can do it.

Incidentally, see that 520hp car in my sig? That's 4 motors I've built for that car, all of them for track racing, and all of them LS1 (and since 2001, LS6) derived. It used to have 580hp but they started emissions testing in this area. [img]i/expressions/face-icon-small-sad.gif[/img]

 

OK, dont know what you are talking about with the GMC link. They dont put the 5.7 in the trucks anymore but whatever, I really dont care anymore. You are getting way off track of what my point was and making this out to be something bigger than what it is. Let me give you this link then. It shows the specs on the different GM motors. (It doesnt include the TBI motors or the truck motors.) And I am Sorry to have obviuosly offended you by useing the specs on the 5.7 motor in our van. But that is what the manual says it has, so that is that. I don't doubt that you know your information. I completely understand that there are many versions of the 350 that are rated at a variety of different horsepower. I was using the motor that I am familiar with for comparision. Sorry to have ruffled your feathers. You can go ahead and make fun of me all you want. I could care less. This got blown WAY out of proportion and that was not what I wanted to happen from my post. There are not hard feelings or disrespect intended to you Shaman. Just a little misunderstanding of what I was trying to convey. With that said, I am letting this thread go.

 

You can't compare engines from significantly different years, as there are changes and advances every year (virtually) in technology BESIDES combustion chamber design. A Dodge Hemi engine in 2004 has more than just the 'Hemi' part to thank for its power. Same with the Vortec/Triton etc... You HAVE to use the same year or close to the same just to eliminate differences in technology besides the technology you're discussing. It's called 'eliminating variables'. Part of the scientific method. Even if you don't know the scientific method, variable reduction is pretty common sense, even among redneck shadetree wrench turners.

I'm not knocking you, or your argument. I'm not trying to be a dick. All I'm saying is that you have to be fair in a comparison, or you'll end up sounding biased. Like some other people have been quick to point out.

We don't even know if the 'Hemi' advancement is largely responsible for the power from the Dodge engine. Maybe they made other changes to increase power; porting, exhaust, cam, ignition/injector mapping, etc... Who knows?

The Hemi deal could be a big gimmick. If it were the hottest thing since Estella Warren, wouldn't everyone be doing it? Just like horizontaly opposed engines, or rotary engines. why the hell isn't everyone doing it if it's so great?