Perrin Light Crank Pulley - Page 4

oab_au · #46 05-22-2003, 05:33 PM

Quote:

Originally posted by elninoalex
For clarification, I did each mod separately and gave it the 'seat of the pants' testing individually of the other mods. Although I didn't run the times separately. I actually don't like pushing the car too much. But I have modded enough cars to get a feel for the before and after difference. And this one was more than I expected. It had about the same effect as putting a light flywheel on my RX-7. Probably wouldn't make as much of a difference on the AT though.

Stephen

For the record:
intake mod- no discernable difference
exhaust mods- noticeable difference
light crank pulley- noticeable difference
5 spd- KICKS ASS!
Nitrous- HAHAHAHAHA!

To save stressing the clutch, box. You could just do acceleration runs from say 60 MPH in third to say 100MPH. This will show any changes in time without the stress.

When working two stroke bike engines they are tested this way to save the engine. A prolong dyno test would wear the engine out.

Reducing the rotational mass can help the acceleration rate of the engine. We do this to bike engines as any reduction in mass is usually a higher percentage of the total mass. It also helps in the way the engine picks up speed, when going down through the gears into a corner, the reduced mass helps to prevent the back wheel from locking up also.

Horses for courses, what works for a race horse doesn't always work for a draft horse.

Harvey.

elninoalex · #47 05-22-2003, 05:53 PM

Trevor- What's the argument here? Are you telling me that I can't tell the difference between faster or slower? It's not that hard mate.

Stephen

elninoalex · #48 05-22-2003, 06:06 PM

Harvey- Unfortunately, I don't have any way to accurately time 60-100 runs. I feel like this mod would make more of a difference on a MT with light flywheel because there is a greater percentage reduction in mass than with the AT. But then again, that could just be my perception talking.

Stephen

Trevor · #49 05-22-2003, 06:32 PM

Only scientific proof is acceptable when such close anticipated variations are involved. Harvey has detailed how best to use a stop watch and I agree with him having used this method for fifty years.

You will not be aware what is going on but there is some under arm effort here. But in spite of that please skip the PREAMBLE and take note of Harvey's last sentence which is the crux of the matter and the meat in the sandwich although he is cunningly being rather obtuse. He is talking about racing cars as apposed to road going machinery, a quallification I have already included

I am out of here as this thread should NOT become another war of words.

Regards to all, Trevor.

Chicane · #50 05-22-2003, 06:33 PM

You know, I've seen this same argument come up in a lot of forums. It seems the engineers think lightweight crank pulleys are dumb, but the 'modders' think they're great.

And then there is the dyno, and I've personally seen a lightweight pulley installed on a neon's 2.0 DOHC engine give the engine an additional 8 horsepower. Dynos don't lie. However, I'm not sure 5-8 horses would be noticeable in our cars, since they're heavier.

- Rob

Trevor · #51 05-22-2003, 06:57 PM

Sorry Rob but unless they ARE a dynomometer, which the ccommon wheel driven contraptions are not, and operator error, tyre pressures variations and the many other factors which are present from one test to the next are taken into account comparitive measurements are not accurate. I have been there and proved this point. Harvey's very simple method IS the best method.

oab_au · #52 05-22-2003, 07:39 PM

Gee Stephen,
I can't count the number of times I have gone out in practice, on a bike that I have done a change to, that I was sure was going quicker by the feel of it, only to see the lap times show it to be slower

I now only rely on the clock.

Rob, 5 Hp A?. First removing mass won't increase HP it can help acceleration times. As Trev says, I have put cars on wheel dynos and found 5Hp without doing anything. Engine dynos don't lie, wheel dynos, don't tell like it is.

Harvey.
p.s. Just wait till you put the scooter on it, and you will see how disappointing it is.

elninoalex · #53 05-22-2003, 10:08 PM

OK Trevor, now I know what you mean by the argument being futile. Because you will never be able to convince me that I can't tell the difference because it's quite easy to, regardless of what you say. Maybe I am just a freak of nature in that respect. So I agree. Let's forget the whole thing.

Stephen

Chicane · #54 05-23-2003, 10:12 AM

It doesn't create any horsepower...it just moves some.

- Rob

#55 05-23-2003, 10:39 AM

Trevor or Harvey,

Please provide one (1) example of a Subaru motor that has been damaged or destroyed through the use of a lightweight crank pulley.

There are literally thousands of Subaru vehicles, many of them in Australia, who are running this type of pulley.

In fact, the most popular brands of lightweight and underdriven pulleys for Subarus are designed and manufactured by Australian companies such as GoFastBits and MRT.

If you could give us an example, and in doing so refrain from subtly calling my intelligence into question, I would appreciate it greatly!

Thanks,

Jason Porter

P.S. - Up until very recently we've been running a 9lb flywheel on the DNT Performance project car... a significantly bigger change than the paltry mass of a crank pulley, no matter how much you might lighten it. The stock flywheel is I believe in the 24lb range. It ran very well in that state for over a year NA and several weeks supercharged until it was victimized by too much boost and not enough fuel due to a stuck blowoff valve.

That's what prototyping is all about.

mbtoloczko · #56 05-23-2003, 02:54 PM

Quote:

Originally posted by Porter
Trevor or Harvey,

Please provide one (1) example of a Subaru motor that has been damaged or destroyed through the use of a lightweight crank pulley.

There are literally thousands of Subaru vehicles, many of them in Australia, who are running this type of pulley.

In fact, the most popular brands of lightweight and underdriven pulleys for Subarus are designed and manufactured by Australian companies such as GoFastBits and MRT.

If you could give us an example, and in doing so refrain from subtly calling my intelligence into question, I would appreciate it greatly!

Thanks,

Jason Porter

P.S. - Up until very recently we've been running a 9lb flywheel on the DNT Performance project car... a significantly bigger change than the paltry mass of a crank pulley, no matter how much you might lighten it. The stock flywheel is I believe in the 24lb range. It ran very well in that state for over a year NA and several weeks supercharged until it was victimized by too much boost and not enough fuel due to a stuck blowoff valve. That's what prototyping is all about.

I'll give my unsolicited 2 cents. :-) There is one guy on NASIOC who thinks his recently deceased WRX motor may have been killed by a lightweight pulley. I haven't heard the follow up on the thread though. What really scares me though are the people on NASIOC who have reported that running a lightweight pulley causes their WRX motor to begin cutting out at ~6500 rpm.

I think that running a lightweight flywheel is not going to have the same effect on torsional vibrations as would a lightweight pulley. The flywheel end of the crankshaft has lots of rotational inertia due not only to the flywheel but the entire drivetrain. Taking a some mass off the flywheel wouldn't change that much. And because the flywheel end of the crank has virtually all the rotational inertia, that end of the crank is essentially anchored with regard to the harmonic vibrations, so its the front end of the motor that needs some mass and dampening to reduce the amplitude of the vibrations at the harmonic frequencies.

Trevor · #57 05-23-2003, 04:45 PM

Quote:

Originally posted by Chicane
It doesn't create any horsepower...it just moves some.

- Rob

Hi Rob,

Please explain what you mean by " moves ". Do you mean " transfers " and if so where to. If you mean does not hold back horse power during acceleration this could be a way of describing the situation without getting technical and I would not argue with that.

regards, Trevor.

oab_au · #58 05-26-2003, 05:54 PM

Quote:

Originally posted by Porter
Trevor or Harvey,

Please provide one (1) example of a Subaru motor that has been damaged or destroyed through the use of a lightweight crank pulley.

There are literally thousands of Subaru vehicles, many of them in Australia, who are running this type of pulley.

In fact, the most popular brands of lightweight and underdriven pulleys for Subarus are designed and manufactured by Australian companies such as GoFastBits and MRT.

If you could give us an example, and in doing so refrain from subtly calling my intelligence into question, I would appreciate it greatly!

Thanks,

Jason Porter

P.S. - Up until very recently we've been running a 9lb flywheel on the DNT Performance project car... a significantly bigger change than the paltry mass of a crank pulley, no matter how much you might lighten it. The stock flywheel is I believe in the 24lb range. It ran very well in that state for over a year NA and several weeks supercharged until it was victimized by too much boost and not enough fuel due to a stuck blowoff valve. That's what prototyping is all about.

Hi Jason. Gee this is going to be difficult to do this without questioning your intel.............

I think the best way to do it, is to return the question in the inverse form.

Can you tell us an Auto Co that builds a modern, high speed, multi cylinder engine, that has the drive taken off one end. What does NOT have a harmonic damper fitted to the other end?????

I mean, Every Subaru has one, even your belovered WRX STi has one.

Don't be mislead by the fact that they are made in Aus. There are as many gullible people here too. We went looking for the Weapons of Mass Destruction also.

Harvey.

mbtoloczko · #59 05-26-2003, 07:39 PM

Quote:

Originally posted by oab_au

... We went looking for the Weapons of Mass Destruction also.

Harvey.

ROTFL!!! :-))

#60 05-26-2003, 09:37 PM

Quote:

Originally posted by oab_au

Hi Jason. Gee this is going to be difficult to do this without questioning your intel.............

I think the best way to do it, is to return the question in the inverse form.

Can you tell us an Auto Co that builds a modern, high speed, multi cylinder engine, that has the drive taken off one end. What does NOT have a harmonic damper fitted to the other end?????

I mean, Every Subaru has one, even your belovered WRX STi has one.

Don't be mislead by the fact that they are made in Aus. There are as many gullible people here too. We went looking for the Weapons of Mass Destruction also.

Harvey.

The burden of proof is on you in this case my friend.

To further return a question volley, answer me this: Show me another company who builds horizontally opposed engines with a crank as short as those built by Subaru.

BTW, I checked... BMW flat-2 motorcycle engines have no harmonic damper. Including the new ones that rev way higher than the old aircooled beasts. I think the new ones rev to something like 10 or 11 thousand RPM?