teh215

iTrader: (8)

Top fuel cars are making around 6000+ HP but they are running 45+ pounds of SC boost with Nitromethane fuel not to mention the insane parts those engines use. I think that the addage of "start big, finish big" holds true no matter the engine make.

myG35zx

iTrader: (2)

Full Size domestic PU Deisels make more than a couple hundred hp stock. After some work (intake, exhaust and program tweaking) it made 325 hp and 650 tq. Oil burners are great. Larger turbos and propane

Sigh...
Back to cars. The toyota Solaro is 9.5:1 and Toyota offers a supercharger - why wouldn't the VQ handle one?

FLY BY Z

Haha. Ignorance is bliss I guess. Ok take the RB26 that made 1300 HP. Lets assume it was a stock bore size. Bore it .040 over. Guess what? It is going to make more power, it has no more potential for detonation as .000 bore and you just increased the displacement. At no cost to detonation, different gas, etc. You can make V-8's rev to the moon, too. The 1.8 revs to 9000 to make 240 HP (S2000?) Wow. That's sad. My bigger displacement motor make 290 and only revs to 6000. My compression ratio is 10.3:1. Yours is 11:1. Hmmm...

cbsuper

Actually, any compression 8.0 and 9.5 would handle FI better than 10.0 or above. Of course, the you can put FI on a car with 10 or above, but the higher the compression the more conservative you will have to be or else you will blow your engine.

SiGGy

HAh, this thead is amusing.

Lets say given equal heads and appropriate fuel delivery for both.

3.5l 8.5:1 = 200hp
3.5l 10.5:1 = 270 hp

5.7l 8.5:1=260hp
5.7l 10.5:1 340hp

both are important.

Larger engines will always produce more power given equal components.

Anyone who thinks differently is nuts.

The more air and more fuel you can get into the combustion chamber the more power you have. (same theory for forced induction)

The higher compression pistons produce the more power on higher octane pump gas.

If your building a N/A engine, you want the highest compresssion you can have for the fuel your running.

Really, you should always want to use the largest engine, and the highest compression for a N/A setup.

And always the largest engine, and low compression for a F/I setup.

F/I setups make smaller engines handle more air/fuel than they can naturally suck in by forcing it with a mechanical air compressor. Technically making it equal to the natural air/fuel intake of a larger displacement engine.

Now take a big engine, and force more into it than it can naturally do. Same thing.

SiGGy

Really you just need higher octane gas to help the problem. And some strong head bolts and gaskets. hehe

jreiter

iTrader: (6)

I also read somewhere that those top fuel engines have to rebuilt after every couple of runs. Any truth to that? I hear stuff like that, and I just get turned off to the whole sport. It just seems like cheating when your engine is tuned so high that it destroys itself so quickly.

That's why I like the 24 Hours of Le Mans races. You have these highly tuned race cars which have to run hard for 24 hours straight. Very cool. (And *then* you rebuild the motors!)

And then you've got the WRC. Not only do they run the engines hard, but they beat the crap out of those little cars. And then they only have 20 minutes between legs to fix what broke. Very, very cool.

FLY BY Z

Yeah but the name of each game is different. In drag racing TF cars the only purpose is to go from a stop to a 1/4 mile in the fastest time you can. Nothing else. No turns, no laps, nothing. Just ***** out be there first. With road type racing you have got to last for laps on end or 24 hrs or whatever. Of course the motors are going to have completely different characteristics for power and reliability. So do their suspensions and tires and chassis, etc. You gotta have an open mind and understand the purpose of the product.

crustydemon

NO...
Displacement is the starting point(choosing a motor).
Compression is a tuning point.

The larger the displacement, the higher power potential.
Compression has limits, displacement don't.

Displacement should be a concern when choosing an engine.
Compression should be a concern when deciding how far you want to go with the chosen engine.

FLY BY Z

I would also like to add to the previous comments that the old vettes:

1) were definitely not running 3 liter 6 cylinders or high revving 4 cylinders. They were high revving 327 ci motors, 350's, and some even big blocks (396 ci and up excluding some 400 small blocks).

2) keep in mind that HP was also measured differently back then which gave higher numbers than todays methods. don't ask me the exact differences because I do not know but I know in the early 80's they changed the standard for which dyno output was calculated. at the crank vs flywheel or something. i don't know.

So basically the answer is that those old cars did have high compression, but they used different fuel and they utilized much larger engines than used today.

crustydemon

That's racing. Even the amature Motocross racer re-rings after 4 or 5 races.

Here is some pretty cool reading. the relevent info begins after 4 or 5 paragraghs...http://www.popularmechanics.com/auto...my/print.phtml

D'oh

I think the difference in HP ratings back then was that they ran the engine bare, with no accessories, in order to get the max ratings. Now, they have to run the engine, water pump, oil pump, blah, blah, blah in quote the numbers that way. There might have been some changes in correction factors, but I know that the accessory thing was changed.

Those top fuel dragsters are pretty impressive. I heard they rev to 9000 RPM, and since they use a slipping clutch they are able to race pretty much the entire 1/4 mile at max RPM (within some tolerance). So, if you say 5 sec 1/4 mile @ 9000 RPM that is only 750 revolutions before a rebuild. Pretty funny.

-D'oh!

350Z 2+2 ???

Hey swifty... nice sig, but you are mistaken. All US spec'ed cars ARE quoted in gallons of displacement. It's all over the brochures I have... my G35 has a 0.924 gallon engine. (not!)

D'oh, you forgot about burnouts, staging time, etc.. So TopFuel dragsters actually go at least 1500revs before a rebuild!

TJZ

As I usually say, correct me if I'm wrong (b/c i often am).

With that said, i believe you are talking about a different kind of displacement. When you say work is force x displacement, that displacement is a distance. However, in a car engine, displacement is the volume of all the cylinders (when is why it's measure in L). (pi)(bore/2)^2(stroke)(# of cylinders).

Again, please correct me if I'm wrong.

f r e z N Y

Your started with a simple blanket statement "Displacement is more important.", so I pointed out simple scenarios that offered counter arguments to lower displacement engines with more "power" than larger displacment engine. The truth is, that whith an increase displacement, you ultimately increase the engine's capacity for producing more power. But as I said earlier, this is an ingnorant blanket statement to make as a guideline for choosing wich engine is "better" or makes more "power". Tuning of the engine releases more "power" through methods such as increasing the compression ratio, ingnition timing, feul injector spray patterns, etc...

The VQ in the pathy and the VQ in the Z, although using the same block, are tuned differently, and thus have different "power" outputs.

Also, take this into consideration. Larger displacement engines will always be heavier than smaller displacment engines. The Z was not designed to be a drag car, it's a sports car.

FLY BY Z

Actually, you never proved that displacement is not more important. It is. And it is not a "blanket statement" although it applies to every scenario I can think of. Everyone here agrees that you can tune for more power with all of your above mentioned methods. Ok. Yes. This applies to big or small displacement engines. The bigger one will make more power with the same level of tune applied. You admit that. Ok.

Now PROVE to me that larger displacement engines will always be heavier than small displacement engines because this is the most false statement on this message board at this present time. I can think of several motors over 400 ci that weigh less than a VQ and probably a lot of today's 4 cylinders. Displacement does not equal material used in construction of a block and it does not mean size of a motor. And if a car is set up right with weight distribution and suspension then it can certainly run a big fat motor. The only reason we don't have small displacement/small cylinder V8's (which I would rather have) is because of things like fuel mileage and purists would have a cow. The Z could handle the same with a bigger motor as it does now. It is all in the setup at that point.

Oh yeah, how in the world can you put the word power in ""???? It is not a sort-of-word or something we are talking about in theory or anything. Power is power, man. You make it or you don't.

dr_gallup

Sufficiently high levels of forced induction can out perform displacement. Back it the days of turbo F1 motors the 1.5 liter 4 and 6 cylinder turbos were way more powerful than the naturally aspirated 3 liter 8, 10 and 12 cylinder engines. The top turbo engines put out 1,500 HP in qualifying trim, good for about 10 laps at best. The race motors were detuned to onlt 1200 HP. Still, a bigger turbo engine will make more power than a smaller one.

Interestingly, if you keep the architecture of an engine the same and scale everything up proportionately the power increases to the 2/3 power of the displacement. This is due to the fact that a limiting factor in most engines is piston speed. So the bigger engine can not rev as high as the smaller engine due to the longer stroke. The power is essentially proportional to the piston area which is why short stroke engines are more powerful (but less torquey) than a long stroke engine of the same displacement.

FLY BY Z

Good info to add, however, it changes nothing.