Anyone Have Lightweight Flywheel + Pulley + Driveshaft?
 

I have a lw pulley and flywheel. The RPMs rise and drop pretty quickly. I wanted to get a lightweight driveshaft but wanted to see if anyone had all 3 that can speak of how the car is with all 3. It is night and day difference with just the flywheel. It takes getting used to, but it is definitely better than stock.
Is there such a thing as too much when it comes to the speed at which the RPMs rise and fall in your opinion? Does it ruin driveability for you/in your opinion?

Thanks for any responses.

Well the LFA revs up and down so quickly that the analog needle can't keep up, which is why it's got a TFT screen with a digital needle. I figure if the engine spinning up and down works for LFA drivers, should work for us too. I thought the pulleys were more of a placebo effect to be honest. Did you do the pulleys before the flywheel?

Ya. I want to say it was noticeable, but maybe it was placebo. It felt like it fell .5 to 1 second faster than stock, not much, but something.

I am tempted to buy the driveshaft just cause, but I can't decide if it's worth it. So many different opinions on driveshafts...

I had all 3 at one point. The flywheel makes the most difference. The other stuff, not so much.

Thanks!

Driveshaft worth it? Just looking for the next part(s) under 1k. I can go with suspension mods instead and maybe consider the driveshaft later. The flywheel is probably plenty fine since it's such a huge difference.

I went from stock to lightweight pulley to a heavier than stock fluidampr and had to try really hard to notice a difference between all 3.

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That is what I have heard. I considered the harmonic balanced pulleys, but as always, there is so many differing opinions on them. I have had my cheapo lightweight pulley for almost 2 years now and as far as I know there are no issues. 45k+ miles on the car, at least half were from with the lw pulley.

What's your goal/purpose? If it's just to rev quicker for fun, I'd skip the driveshaft.

I was just looking at my next upgrade. I just got a new clutch/flywheel and it's changed the tach significantly. Takes getting used to, but I like it.

So my goal is just figuring out what to buy next.

Suspension mods (minus coilovers)
Brakes (probably too pricey until I get turbo)
Rotors/pads
Rocket bunny stuff (maybe, still up in the air if I want to chop my car up)
Aesthetics...

I'm just browsing for the next small <$1k project.

I have:
Wheels + lugs
Coilovers
Short throw
Pulley kit
clutch/flywheel
full exhaust
OFT
Intake (just cause)
Valentis
mud flaps (looks)
and a couple little things here and there.

So I was considering the driveshaft to keep the upgrades moving along, but was wondering if it's worth it at all, now or later to get the driveshaft.

Nope :p

I did some calculations a while back regarding what kind of inertial losses you can recover by going to lighter weight rotational parts. Translated into hp, I think a cf driveshaft should have the same effect as adding about 2hp in a second gear pull. Less in 3rd, more in 1st. That's just estimated rotational losses with some assumptions. I didn't go back and do the hard math to factor in changes in acceleration and recalculate. I'll look up that spreadsheet next time I get on my PC to confirm.

Edit: cf driveshaft gets you about 1.5hp back in second, a -7lb from stock flywheel gets you 6.

I have all 3 plus lw wheels and gutted interior, I got the aluminum driveshaft last and yes you can feel the difference!

Firstly. There is a critical mass of flywheel (that is, going too light) when combined with lwcp can result in engine failure. This was posted by a respected tuner on these forums but I can't be bothered looking for it.
Secondly. I am hypothesising that rpm drop is ecu limited. If the throttle closes too quickly emissions go up.
Third. Carbon drive shaft is great for total weight saving not so much for reduced angular inertia.
Fourth. Lighter wheels make a great contribution to everything. Well, not everything but they reduce total mass, reduce angular inertia, reduce unsprung weight. Makes no difference to the GDP of Finland.

I always try to get the lightest wheels. I had 17.5lbs Kosei's K8R, then got 18x9.5. I think they are 20 or 21lbs each : (. Lightweight wheels get way too pricey at that size for my liking.

I could see the shaft causing trouble. The flywheel drops the RPMs in a split second as opposed to 1-3 (maybe 4) seconds. It's stupid fast now. It also alters the sound because of how quickly it drops. Vrm instead of Vrrrrrm lol.

Light crank pulley is a useless and aesthetic mod pushed by lazy companies. Use OEM or use a proper piece like a Fluidampr pulley.

Technically, lighter pulleys, drive shaft, flywheel, and wheels all contribute to lower inertia and hence faster acceleration. In terms of effect on the angular inertia, per lb in weight reduction, the order of significance (from large to small) is:

(1) flywheel; (2) wheel; (3) pulley; and (4) driveshaft.

Also, light weight lug nut will also help (ever so slightly).

The incremental improvement of adding each of these light weight parts may not be so apparent. But the opposite is true: ie the result of replacing these light weight parts with their oem, heavier parts, is VERY apparent. It feels like adding a 100lb sack of potato to the trunk.

Please remember none of these light weight part adds power, per se. They only reduce inertia of the drive train, and hence better acceleration (and deceleration). The effect is applicable at all times at any rpm.

The effect may be vey tiny at all RPMs when the car is out of gear. As soon as the car is in gear and powering the driveline then any difference is so slight that is would not even be measurable muchless noticeable. It does not make any difference if you saved 2 ounces on a pulley once the tranny becomes engaged. The engine speed is now restricted by the gearing not the weight of some outlying minor components. The theory and the reality are two radically different things in this case.

I generally avoid buying anything from those manufacturer brands which have such useless, and often overpriced, parts among their products.

Which company is exactly lazy and overpriced? A company like the following one?

http://i64.tinypic.com/dfgm15.jpg

Yes, they have also lightweight pulleys and driveshafts. Because they are simpler mods and not anyone wants or willing to open the engine. Our ignorance, doesn't mean that they are useless.


@OP: I like your mods. Unfortunately, the faster drop of RPMs requires faster gear changes which is not always optimal on a street car. Personally, I would choose as next mod the thicker rear axles.

https://www.sti.jp/parts/subarubrz_z.../ST28421AS100/

Enlighten the ignorant, then. I am ready to listen. You can start with presenting the data for fly wheel upgrade and drive shaft, for example. How much improvement in power and acceleration? Give the numbers.

Why would I start a discussion by giving names of manufacturers that I don't care about. I can give recommendations, though. How about my highest recommendation for Jackson Racing that increased my power to 300hp. Your turn. But no unsupported crap please.

See post 11. I didn't calculate pulleys because I was lazy, and I wasn't expecting more than 1hp return based on the other stuff. Was thinking of fixing up my drive line inertia calculator to make it easier to use and posting it. I just did a rough calculation once because I was curious.

Cars are complex systems with many parameters and a physical model is an over-simplification. We cannot know the engine's potential, until we measure the effect of a specific kit.

Here are the gains of a pulley kit with a small under-drive on the alternator. The measurement was made on 4th gear by Toda:

http://i67.tinypic.com/118gggh.png

The gains are between 3-10 hp in the entire RPM range. You asked about numbers and you got it.


I won't start a discussion of supercharger kits here. It is irrelevant to OPs topic.

^ Graphs that say power increases with lightweight pulleys and Fluidampr ones that say it decreases. This is getting fun.

Fluidampr is a heavier pulley comparing to stock and has an entirely different function. I've seen respected Japanese tuners to use it on supercharged or turbo 86/BRZ cars for increased engine reliability. It is a good option if you are going with FI. On a NA car they are saying that it is not really needed.

Anything in real world data that can be related to actually driving the car, and not just the engine on an engine dyno, where there's absolutely zero drivetrain loss? Or are you just going to prove that you're just a huge sucker for marketing material once again?

You can see my car's modification journal and the majority of the changes are from Subaru / STI. Even the Toda's bigger throttle body is a slightly bored factory part. Reason going with them is because STI never touched the engine. Not to install a turbo, but to make some refinements the way they did on handling. So, it is funny to be accused that I am huge sucker of Toda's marketing material, when I am using basically factory parts.

If you or other people can't get over of what they bought and searching about huge improvements it is not my problem. It is your problem.

I asked Perrin if installing an ACT SB7 with Streetlite clutch, with a lightweight driveshaft, and with Perrin's three lightweight pulleys would damage the engine. Here's their response.https://uploads.tapatalk-cdn.com/201...5795a5b5f0.jpg

Thoughts?

Yes in some older Subaru engines, if you were combing a lightweight driveshaft with a lightweight pulley you could get a CEL miss-fire code. It was known to happen if you were going lower than a specific weight. It wasn't known if there was an actual miss-fire or just the ECU was throwing a code. I've not heard something similar in our engines.


A final remark concerning different lightweight pulley kits. There are some cheap ones and some quite expensive. The difference is not related with the marketing department of each company, but the used material. You replace a steel pulley with an aluminum one and it is important to not have a failure. It is known that 7075 aluminum material is much better than the cheap aluminum, with a strength comparable to many steels. However, it is more expensive. So, you get what you pay ...

Which companies make pulleys out of 7075 aluminum for this platform?

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I am aware that Beatrush of Laile (laile.co.jp) uses a 7075 grade.
http://www.beatrushusa.com/product-p/br.s96400pa.htm


Another brand is Toda Racing, but I place it second. I don't want to be blamed that I am sponsoring them.

Speaking from my experience with the light weight pulley, light weight flywheel and light weight driveshaft. I had the T3 light weight pulley, TODA racing chromoly flywheel and 1piece carbon driveshaft on my AE86. I don't have number to prove but I can tell from the way the handles and accelerate that it have more power on the wheel than when I don't don't those installed. Yes, I also swapped to stock parts after installing them to see the difference and then back to the after market. I plan on getting the pulley and drive shaft for my frs.