How to get faster rpm's?

[isaiddurazoo]

Okay I hope you guys have time because I don't understand this concept very well.

1. Do rpm's not equal speed because of transmission gearing?
(It would just make sense to me if an engine was spiining at 9k rpm it would be releasing more power than a bigger engine at 6k.)
Obviously that's not the case, but why?

2. I've heard our cars have very short gearing. If so, why do out rpm's travel so slowly compared to a honda civic for example.

3. While we are on the subject, how come our cars tend to pull so hard in 3rd gear?

4. How would I get my rpm's to fly up there real quick? I like fast rpms.

 

[Calan]

You really, REALLY need to spend some time on Google searching for some basic introductions to automotive technology.

You'll have a lot better luck learning the basics there (or God forbid, by purchasing a good book). Then post in here with specific DSM questions...after searching here as well.

 

[clipto]

You want to reduce work on the engine like the power steering a/c belt and all pulleys that drive on the motor reduce engine rev in the rpm range so the less the turbo has to rotate the more faster revs you get. Also a fast spooling turbo helps.

 

[gsx50501]

Okay I hope you guys have time because I don't understand this concept very well.

1. Do rpm's not equal speed because of transmission gearing?
(It would just make sense to me if an engine was spiining at 9k rpm it would be releasing more power than a bigger engine at 6k.)
Obviously that's not the case, but why?

2. I've heard our cars have very short gearing. If so, why do out rpm's travel so slowly compared to a honda civic for example.

3. While we are on the subject, how come our cars tend to pull so hard in 3rd gear?

4. How would I get my rpm's to fly up there real quick? I like fast rpms.

1. the transmission uses gear ratios to make speed so things are not always spinning at the same rpm. thats the easiest way i feel i can explain that.

2. well for one a civic is fwd not awd. they have a lot less mass to move. the gear ratios are not the same as ours.

3. that is a matter of opinion its on the tune!

4. Less rotational mass. light flywheel. lightened crank. just less weight all around will help, but then again if your awd thats a lot of it.

 

[WES_393]

Okay I hope you guys have time because I don't understand this concept very well.

1. Do rpm's not equal speed because of transmission gearing?
(It would just make sense to me if an engine was spiining at 9k rpm it would be releasing more power than a bigger engine at 6k.)
Obviously that's not the case, but why?

2. I've heard our cars have very short gearing. If so, why do out rpm's travel so slowly compared to a honda civic for example.

3. While we are on the subject, how come our cars tend to pull so hard in 3rd gear?

4. How would I get my rpm's to fly up there real quick? I like fast rpms.

1. RPM's do equal speed, but it depends on the gear. But if gearing is the same, then RPM always equals a certain speed regardless of power. So 3k rpm in 5th gear is the same for my 300hp DSM as it is for my buddies 500hp DSM (around 65mph if I'm not mistaken). This is the gear ratio.

2. Our cars do not have very short gearing compared to most other sport compact cars. From my experience, it's just about on par with most sport compacts from it's time, including the Civic. All the Honda's you see bouncing off the rev limiter are either A) Spinning the tires B) Have the car lightened significantly C) Making a good amount of power (though rare). You want to drive a DSM with short gearing, take a ride in a Spyder GS. 1st gear is bouncing off the rev limiter at 20mph.

3. Our cars pull so hard in 3rd mostly because of the load. High load = higher timing and quicker spool. It's also a pretty tall since it takes you from 60-100. But like mentioned, this is all in the tune and build. Install a PTE 6266 and 4th gear will quickly become your new favorite.

4. The answer is simple: Horsepower. Given the gearing stays constant, horsepower is basically how quickly the engine can accelerate a given load. To get technical, Horsepower is the ability to move 550lbs a distance of 1ft in 1 second, or 1hp=550ft.lbs/sec. So a 500hp DSM will cycle through gears very quickly compared to a stock DSM, and it will do it in a shorter distance (More ft.lbs/sec), hence the faster 1/4 mile times. You can't decrease distance, so you either decrease weight (Honda technique) or increase acceleration (True power).

 

[isaiddurazoo]

Thanks a lot! That gives me a pretty good idea.

FTR I do read very often. I just come on dsmtuners to be reassured, a lot of people on here seem to be pretty knowledgeable. I come on the newbie forum to ask my newbie questions. If that bothers you... maybe you're missing the point of this space here. If we wanted to figure everything out on our own we could, but then what would be the point of coming on here? Telling other people to read a book.

To the rest of you, thank you for your patience and time.

 

[DSM1G90]

The gear ratio is set for the amount of torque output of the motor since our motors are just 4cyl motors, the final ratio has to be what it is (4.16 to 4.22/1 depending on the setup) to reach the proper power band per torque output.

Otherwise, the motor will be under or overworking itself and destroy itself in a heartbeat.

A 2G car,esp a "ragtop" is a heavy beast on the road weighing almost 3000LBS due to the much more beefier body with added steel to stiffen up the body, since the factory cut off the roof, went cheap and put a hunk of canvas up there.

You lose the roof, you lose the support that the body needs to keep it together. Thus, extra metal has to be place in areas to compensate for the loss of the roof .. and that definitely adds weight to the equation.

And you got four rats whirling around in each of their cages up front trying to move all of this weight .. just ain't gonna happen unless you add three more rats per each cage to get more HP out to the front tires to move that extra mass more forward.

Why some "Spyder" owners do the 2.3L "Stroker" trick to their motors to get that increased low end torque to really move that beast faster and sooner down the road.

 

[dtmoke]

Among other things, I believe a lightened flywheel will help with quicker revs.

 

[Diamond Star Werks]

A set of evo8 cam shafts will take a good bit of weight off the top end which will help with faster revs.

 

[micha118833]

lighter flywheel and lighter pulley's will help you rev up quicker which is what i think you are refering to when you say quicker rpm's

 

[SPYDERGSTTUNER]

lighter pulley's will help you rev up quicker

On turbo dsms it is not recommended to replace your crank pulley with a lightweight one since it helps dampen vibrations caused by the rotating assembly, although there is other options such as fluidamper or similar. You can probably replace your accesory pulleys to lighten it up a bit but not enough to even notice the difference. Im surprised no one has mentioned a lighter rotating assembly( I-beam rods,pistons,butcher crank etc) Less weight to rotate equals revs like a crotch rocket

 

[WES_393]

Im surprised no one has mentioned a lighter rotating assembly( I-beam rods,pistons,butcher crank etc) Less weight to rotate equals revs like a crotch rocket

What I think everyone is as assuming is that the OP is talking about free revving when he means actual acceleration. Lightweight flywheels, pulleys, lightened assemblies, etc will only make the car free rev faster, not accelerate faster. At least not noticeably faster.

 

[Cdc1221]

Wes is right. You can build a fast revving engine that will rev to the stars, but unless you realllly lighten the car, or realllly shorten the gearing, or both, it wont rev like a rocket. Now if you could get the weight down to say 1500 lbs, it might be a possibility. But normally its just cheaper to build our cars for more ponies and leave the lightweight stuff to formula 1