GtoRx7

iTrader: (5)

I agree fully with that as well.

jimlab

The only pulls were done on base maps. It was never tuned because igntion breakup prevented a clean pull.

The comment was intended more for your new-found friend rarson.

And which thing would that be?

KaoticFdR1

I decided tonight that an LS1 is in my future. This rotary is just pissing me off. I love it to death but i need something with a little more of the "IT" factor.....mildly intoxicated but some should get it.

rarson

Jimlab, I'm not sure how to take your comments. Honestly I did not read the whole thread and I was only offering my take on the subject. Whether or not my argument agrees or disagrees with GtoRx7 is totally coincidental, though I will say that his car is badass.

My whole point was that horsepower and torque are intrinsically related, and the truth of the matter is, you can't really have one without the other. One of my favorite cars I've ever driven was an RX-8, and the reason is because it's torque curve was so flat. And that's the true goal of a high-performance car. Sure it's great to make a lot of torque down low, but it's even greater to continue making that torque for the next 5000 rpm. The RX-8 was just FUN to drive.

I get tired of people ******* on Hondas, for instance, because they make less torque and make more power higher in the rpm band. The end result is basically the same, with a different emphasis in a specific part of the rpm range.

I spent 2 years in training on Naval nuclear propulsion systems. I know quite a bit about horsepower and torque and the effects of gearing. My point was simply that gearing can make torque out of horsepower. Though, I suppose it should go both ways; an engine making massive torque down low should be able to convert that force into power the same way that a Honda revving up high can.

All in all, it's just a different means to the same end. I really don't see how there is a right or wrong on either side of the horsepower vs. torque argument. If I am wrong, please correct me and explain why. I would love to know if there is a definite answer to this. As far as I can see, there is not. Thank you guys, for the good discussion (let's keep it civil).

Nihilanthic

rarson, a flat torque curve with a nice bump at the left end of the graph (same shape as the RX8s) but squished within less rpms, bumped up in the foot pounds, but having the same (or more) power and longer gears to match it up would feel exactly the same... it would just sound differently and the needle wouldnt move as far on the tach, unless you had the little thing in the corner saying "x500" instead of "x1000"

The reason the hondas are crapped on so much is that they have a FLAT torque curve, and thus thier powerband is relatively narrow. Having midrange torque and thus a bigger powerband is preferred - however, the honda guys POV, that theyre making peak BSFC throughout the powerband, and not just the midrange, still holds true.

But this has degraded from a semantic dispute into a pissyfest, anyway. We all know that if we had a variable intake and 'vtec-like' heads/valvetrain on a big (5+liter) motor it would be absolutely amazing. Peak BSFC from idle to a stellar redline would not only be an accomplishment but also make for an exciting drive.

All us domestic 'cowboys' are saying is it would be just as easy to have even more displacement, a static cam, and flat POWER with a torque peak in midrange, make just as much power, and probably cost less to do that way, and have a smaller engine overall if you use those amazing things we call 'pushrods'.

Well, that and/or a turbo... pick yer poison.

jimlab

For what it is, sure. An FD powered by a stock LS1 would thrash it, though.

Now explain that to GtoRx7 so he can agree with you.

It probably was... if your experience with "performance cars" is limited to Hondas. If you'd driven a stock 3rd gen. afterward, you'd have a different opinion, I suspect.

Is that why you can thrash a Honda S2000 with a Supra TT using only half-throttle?

Gearing can only amplify available engine torque, it can't create torque out of thin air to widen an engine's powerband. It can, however, help the engine get into its powerband sooner.

An engine with a narrow, peaky power band will still have a narrow, peaky powerband after increasing gearing; it'll just be a little more liveable on the low end. It will also have to turn more rpm to make up for the reduction in terminal speed in each gear caused by the shorter gearing.

The 3rd gen. RX-7 and RX-8 are perfect examples of this. Very little low end torque, but they're liveable because they have incredibly short gearing; 14.28:1 in 1st gear for the RX-7 and 16.69:1 for the RX-8. By comparison, a base Corvette only has a final drive of 9.10:1 in 1st gear, and a Viper is only 8.16:1. They don't need a gearing boost thanks to their displacement (and therefore low end torque) advantage.

GtoRx7

iTrader: (5)

Well, while we are on the subject I want to know the answer to this question. While at the drag strip with my first FD, five years ago, I was running consistant 14.3's @100mph pass after pass, the car was all stock with crappy tires. Another FD was there all stock as well running 14.1's @102 all day long. Both his and mine were touring models, with the weight in the 2,880lbs range. Now there was a S2000 there, and was also bone stock, they weigh in at 2,840lbs or something close to that, and 240hp, and it was running 14.0's and 14.1's@ 101mph all day long. Now a FD has 216ft-lbs of torque, and much more power under the curve (horsepower) than the meager 145 ft-lbs the honda has. Weight is very comparible, so how is it these two cars can run with each other down the 1320? If you say driver error, its possible, but the reaction times were super close for all of us, and going by magizine tests they were in the close percentage in the quarter. Yeah I know the R1 has turned a 13.5 in tests, but thats the best of the best, and you'll hardly ever see it at a local track.

GtoRx7

iTrader: (5)

That you have to have the last word, or post, always, no matter what.

You really think so? This year or last year? I will find out for you soon.

Isnt it true that for a given amount of displacement, you can only get so much torque out of it (non-forced induction) given todays technology. I have found on piston engines of today, its around 75ft-lbs per liter n/a, and rotarys to be about 60 ft-lbs per liter. This is on regular gasoline as well. So given a honda, its can only get so much torque, and for my engine it as well can only get SO much torque. So to make it as powerful as possible, the only thing at your disposal is to make it breathe and rev higher to get the limited amount of torque it has up into higher rpms.

jimlab

Lesse...

1. Very similar gearing
2. Better launch
3. 9000 rpm redline
4. Power shifting
5. Driver weight
6. Fuel weight
7. Engine/coolant/oil temperature
8. Production variances

Are you sure about that? Have you compared the two torque curves and calculated average torque for each?

Reaction time has absolutely nothing whatsoever to do with E.T. or mph. 60-foot times are what you should be looking at.

jimlab

You seem to be doing a good job of the same. Or were those multiple posts about agreeing with what everyone else was saying just the result of a bad case of hiccups where you accidentally hit the post button each time?

Try recalculating with your rotary's actual displacement (4.0 liters), and I just posted a chart for a naturally aspirated 396 that made 86 lb-ft. per liter untuned, and was not built for maximum torque (~3" long intake runners).

Other than increasing displacement or using forced induction or nitrous, yes.

GtoRx7

iTrader: (5)

Gearing for S2000-
1st-3.12
2nd-2.05
3rd-1.48
4th-1.16
5th-.97
6th- .81
4.10 rear end

gearing for FD
1st- 3.48
2nd- 2.015
3rd- 1.3
4th- 1.0
5th- .719
4.10 rear end

Yeah the FD is shorter geared in 1st and 2nd.

OH, so how is 9000rpms helping at all? The rear wheel torque is less on the s2000? Thus acceleration is less as well, following a lower torque line? How can it keep up? Is it horsepower? Is it force over time? Hmmmm. Jim is starting to contradict himself.

I havent found two stock dyno charts to compare, but yeah I am pretty sure. Maybe you could help us find out?

Yes I know this, it was more of a relation to driver ability, proving the FD and s2000 drivers werent newbies.

jimlab

In first gear, at any rate. I think we've already established that math isn't your strong point.

Higher wheel speed in each gear and potentially less shifts in the quarter mile. Shifting wastes time, if you weren't already aware.

Now, consider the gearing advantage the S2000 has in 3rd gear. For every lb-ft. of torque in 3rd gear at any given rpm, the RX-7 has to produce 1.14 lb-ft. to match it, and therefore match the rate of acceleration, assuming both cars have the same size tires and very similar weights. 0.14 lb-ft. doesn't sound like a big difference, but it adds up quickly.

3rd gear final drive (Honda vs. RX-7)
6.07:1 vs. 5.33:1

120.0 lb-ft. * 6.07:1 = 728.4 lb-ft.

136.7 lb-ft. * 5.33:1 = 728.7 lb-ft.

Now do you understand why you can't always just compare two peak horsepower numbers and arbitrarily make an assumption about which car is faster, even if you know the weights of the two vehicles?

You should really think your posts through for a longer period of time before hitting the submit button. It could save you a significant amount of embarrassment in the long run. I listed several reasons why the S2000 could have been quicker than it is on paper.

I could, but I wanted to know if you actually knew how to compare area under the curve.

Just FYI, the average is 128 lb-ft. vs 162 lb-ft. from 2,000-8,000 rpm. The FD should have the advantage if...

1. It didn't weigh more because of fuel level and driver weight
2. The driver was shifting at the appropriate rpm (redline isn't the correct answer)
3. Power output of the two cars was exactly average for each model
4. The S2000 was truly stock

There are several other factors I could list, but why bother. You wouldn't read them, and even if you did, you wouldn't understand them.

For example, do you know what DA is and what effect it has on an engine's performance depending on whether the engine is naturally aspirated, supercharged, or turbocharged?

Again, the 60-foot times would be a better indication of that than reaction time. So they left at the same time. Big deal. Were they even good reaction times? Never mind, I don't care.

GtoRx7

iTrader: (5)

where did you get these torque values?

jimlab

Thin air.

It was only an illustration of how much more torque the RX-7 would have to make in 3rd gear in order to match 120 lb-ft. (which is within range, given a peak of 144 lb-ft. @ 7,000 rpm) for the S2000, thanks to its gearing advantage.

GtoRx7

iTrader: (5)

Hahaha, that is great. Im pretty sure a FD always has more torque than that except at idle up to 2,200rpm!

capn

Just for the sake of the argument here are some dyno graphs for the LS2 and the rotary NA engine. I chose the NA version of the rotary because we are comapring two NA engines here. From what I can glean from these two plots are that the LS2 makes MORE torque sooner and keeps making it. While the rotary plots have very little torque under 2500rpms ( I threw in a 13bre for good measure). You can see that although it [13bre] does have a high peak torque it has a smaller amount of area under the graph (as jimlab was mentioning before), so more area under the curve is better, I hope the pictures will help you visualive that.

LS2 plot(pdf form): here



13b na:


13bre:

jimlab

Thanks for proving that you're incapable of understanding a real-world example that demonstrates the effect gearing has on torque, and why you can't just compare two torque curves without factoring in gearing.

Maybe if I'd used an analogy about cake or a diesel engine?

capn

maybe you should use rye bread as an example of a v8 torque curve and a cheese wedge as a rotary torque curve? I Don't know these days, kids suck at the metaphor part on the SAT, I tried to use pictures in my last post.

Andrew.

iTrader: (4)

You sure thats a NA? Thats alot of torque for a NA, I know it says NA, but at the bottom it says T2, weird..

capn

The picture says 1986 N/A; T2 may just being refferend to the run number.

FWIW I got that Dyno sheet from the fc3s.org project 86, I am pretty sure its NA only modified tho.

GtoRx7

iTrader: (5)

That is a turbo 13b, running out of boost? Or supercharged. You can't pull torque by large amounts from bolt on's and porting, it only shifts it higher or lower in the rpm where peak torque occurs, as you know. Here is a dyno from my 3-rotor last year,it is a true non-turbo. (yeah it sucks ***, but it was the first ever dyno, so give me a break). Tell me the power under the curve on it, and how bad it is. Seriously I would like to know.

capn

ok for starters, where is the torque below 3000rpms? is it just bad tuning/first pull, what? I do not see torque there.

ok I have modified your graph and I hope this helps you see what we are talking about here



OK hopefully as you can see the Cyan color represents the area under the curve for the Rotary torque curve. And the red triangle to the left side is the area that a V8 would normally displace along with the cyan area. This shows the "down low" area that most rotaries are lacking, and which V8s have and are known for. That little trianle is "more area" and by more area there is a wider powerband which means more torque. Does this help explain the "area under the curve"?

rarson

WOW, it must be really sad to limit yourself to driving cars solely based on horsepower. For your information, I've driven many cars, including a well-modified Supra TT. Have you ever driven an RX-8? Do you ever take any turns?

I drove a friend's RX-8 following another friend's '95 GTS-t Skyline around a few twisty roads on Guam. He couldn't pull away. Now I guarentee you that I was probably pushing harder than he was, but he was a bit red in the face when I stayed with him the entire time. So much for your 3rd gen comparison (as the Skyline is quite a bit faster than a stock FD).

Please tell me where I said that gearing would "create torque out of thin air to widen an engine's powerband." BTW, POWERband refers to POWER. Horsepower. Torque is not power.

Uh... yeah, thanks for restating what I've already said.

Didn't you just finish telling me that the 3rd gen RX-7 was a completely different animal than the RX-8? I really couldn't give a **** what the final gearing in first gear is for a car, I just care how the car drives.

As I'm sure you've noticed, the tone of this post is much harsher than the last, but that's only because it's hard (and annoying) to reason with someone that presents themselves as such a know-it-all.

rarson

Jesus christ! You people don't comprehend what you read, do you? THANK YOU ONCE AGAIN for repeating me! Now enough of that crap!

I love it when people who haven't driven Hondas try to talk about Honda powerbands. Excuse me, but Jim was saying "Have you ever driven an FD?" Well what about you guys, have you ever driven any of the other cars out there or are you so set in your ways that you couldn't possibly ever consider driving something as tame as a Geo Metro (let me tell you, that's a fun car to drive)?

Hondas do have midrange torque. And high-rpm torque. That's why their power curve goes up up up up... It's simple multiplication, we all know the equation for horsepower...

If you think that Hondas don't make torque, please go look at a K20 or K24 dyno chart and school yourself.

Ha! Well since Honda is the only company that currently makes variable valve lift engines, I guess we'd have to purely benchrace... errr, speculate! By the way... since you don't seem to understand the function of VTEC, it's there to provide hot cam performance in the upper rpms and driveability in the lower rpms. So with your theoretical big motor, with 2-valve heads the power is still going to drop like a rock north of 6500 without massive amounts of head work. That's why it's pointless to put "VTEC" on an 2-valve OHV V8... unless you have some really monster cam that can't idle, but I've seen cars that run 8's idle on some big cams... so...

Wow, you really don't understand fluid dynamics, do you? Do you honestly think the presence of pushrods has an effect on the torque curve? A 2-valve OHC engine will act virtually the same as a 2-valve OHV engine. I'm not arguing against pushrod motors or against producing torque; in fact, I said that the argument is pointless. And I also don't understand why pushrod motors are considered a "domestic" idea.

I think you guys just like arguing for the hell of it. This thread is now officially retarded.

Orr89rocz

agreed... although ohc heads tend to have better low lift flow numbers than ohv heads and can make abit more low end power but it mainly comes down the the cam profile and intake design.

and yes there is NOTHING wrong with pushrods.. they are great motors and have been doing good for years. LS1 for instance has been doing great and is one of the finest n/a motors made. it is even more impressive under boost. the C5-R racing team that has been DOMINATING over the last few years has a big inch push rod motor and hasnt had reliability problems