Improve throttle response

[Wally86]

Originally Posted by drewbot

when you get lucky and finally just get the tip in, do you immediately start banging your gf/wife/one night stand immediately at 100%?

This thread necro was worth this underrated quote. And the answer for everyone is "of course".

[CrowsFeast]

Originally Posted by daiheadjai

I'd like to add that a lighter crank pulley made a difference on my 2013.
Some people will swear it's a placebo effect, but I definitely felt better response when I had a Kartboy pulley installed (1lb vs. the stock 4lb), and noticed the immediate difference when I swapped back to the stock pulley before I returned my BRZ lease. As the FA20 is a boxer, it is safe to change this pulley (it doesn't affect any sort of dampening or counterbalancing).

I'd recommend a Perrin piece though, as the Kartboy produces a noticeable (but low) whine. And definitely see if you can get it used (just in case I'm wrong and it really was just a placebo effect).

Less rotating mass is always going to aid acceleration; whether it's enough to notice or not is another question.

I am however curious about your claim that because this is a boxer motor there's no need to do any dampening. horizontally opposed or not, there's always going to be vibrations and such. If there was no need to dampen them then the OEM would have saved themselves the extra material and cost of making the harmonic damper. That said it may not reduce the engines life by a noticeable amount for most people.

[dragoontwo]

Originally Posted by CrowsFeast

Less rotating mass is always going to aid acceleration; whether it's enough to notice or not is another question.

I am however curious about your claim that because this is a boxer motor there's no need to do any dampening. horizontally opposed or not, there's always going to be vibrations and such. If there was no need to dampen them then the OEM would have saved themselves the extra material and cost of making the harmonic damper. That said it may not reduce the engines life by a noticeable amount for most people.

I have read on this very forum that the OEM crank pulley is not a harmonic damper.

[daiheadjai]

Originally Posted by CrowsFeast

Less rotating mass is always going to aid acceleration; whether it's enough to notice or not is another question.

I am however curious about your claim that because this is a boxer motor there's no need to do any dampening. horizontally opposed or not, there's always going to be vibrations and such. If there was no need to dampen them then the OEM would have saved themselves the extra material and cost of making the harmonic damper. That said it may not reduce the engines life by a noticeable amount for most people.

Same as dragoontwo - I read from here (this was a subject of vigorous debate at one point) and the conclusion was that the OEM piece doesn't function as a damper?

[CrowsFeast]

Originally Posted by dragoontwo

I have read on this very forum that the OEM crank pulley is not a harmonic damper.

Well, guess I should have done some research then.

Why does it weigh that much more though?

[dragoontwo]

Originally Posted by CrowsFeast

Well, guess I should have done some research then.

Why does it weigh that much more though?

I can't really answer that but here goes anyways. The pulley is a 3 pc design with 2 metal pieces connected my a thin layer of rubber. It is probably as light as 2 mass produced cast metal pieces and a strip of rubber can be. It is probably much cheaper to produce than machined aluminum pulleys are.

[DarkSunrise]

LWFW made a huge improvement for throttle response. Slight blip is all it takes on downshifts.

I'm also on an E85 tune and whenever I go back to stock tune, I notice the throttle response is not great (yes, after the adjustment period).

Love the throttle response on the car now!

[PenGun]

If you are seriously using the car, you will be over 4500 RPM at the least. You may find the harder you drive it the better it feels. In drive to the store mode, it has many peccadilloes.

[CrowsFeast]

Originally Posted by dragoontwo

I can't really answer that but here goes anyways. The pulley is a 3 pc design with 2 metal pieces connected my a thin layer of rubber. It is probably as light as 2 mass produced cast metal pieces and a strip of rubber can be. It is probably much cheaper to produce than machined aluminum pulleys are.

I'm guessing that rubber is overmolded, which is surprisingly not all that cheap. Sounds like it's not functioning as a traditional harmonic dampener maybe, but it's definitely still dampening some vibrations if it's 3 piece with rubber in the middle.

[dragoontwo]

Originally Posted by CrowsFeast

I'm guessing that rubber is overmolded, which is surprisingly not all that cheap. Sounds like it's not functioning as a traditional harmonic dampener maybe, but it's definitely still dampening some vibrations if it's 3 piece with rubber in the middle.

In the quantities that they are done, it may still be cheaper than machining a bunch of 1 pc pullies.


I agree that it is likely just a slight dampener, and not a balancer.

[CrowsFeast]

Originally Posted by dragoontwo

In the quantities that they are done, it may still be cheaper than machining a bunch of 1 pc pullies.


I agree that it is likely just a slight dampener, and not a balancer.

1 piece pulley will always be cheaper to manufacture. It would be mostly cast and then just touch up the running surface (which they would be doing in any design).

I was actually speaking from my experience when I worked at continental on valves for evap systems (making million of parts) about overmolding being 'expensive'.

[Baldeagle]

Originally Posted by CrowsFeast

Less rotating mass is always going to aid acceleration; whether it's enough to notice or not is another question.

I am however curious about your claim that because this is a boxer motor there's no need to do any dampening. horizontally opposed or not, there's always going to be vibrations and such. If there was no need to dampen them then the OEM would have saved themselves the extra material and cost of making the harmonic damper. That said it may not reduce the engines life by a noticeable amount for most people.

Sorry to bring up a potentially dead thread, but I just did some reading on this subject. It seems the OEM pulley is designed to quell certain vibrations. Assuming the internals of a boxer engine are balanced, it has no primary or secondary balance vibrations. (It does of course produce a rocking couple, which gives the flat four its notorious rumble.)

However it seems that at high rpm, an H4’s crankshaft incurs flex and that flex causes a vibration. The OEM two-piece pulley with the rubber ring is designed to absorb some of that vibration. If the rubber in the pulley were not present, the crankshaft’s bearings would absorb more of those flex-vibrations. Over time, that could increase wear on the crank bearings and reduce the engine’s lifespan. To what degree does this have an impact? I am clueless. But it seems there is a purpose for that rubber ring.

[daiheadjai]

Originally Posted by Baldeagle

Sorry to bring up a potentially dead thread, but I just did some reading on this subject. It seems the OEM pulley is designed to quell certain vibrations. Assuming the internals of a boxer engine are balanced, it has no primary or secondary balance vibrations. (It does of course produce a rocking couple, which gives the flat four its notorious rumble.)

However it seems that at high rpm, an H4’s crankshaft incurs flex and that flex causes a vibration. The OEM two-piece pulley with the rubber ring is designed to absorb some of that vibration. If the rubber in the pulley were not present, the crankshaft’s bearings would absorb more of those flex-vibrations. Over time, that could increase wear on the crank bearings and reduce the engine’s lifespan. To what degree does this have an impact? I am clueless. But it seems there is a purpose for that rubber ring.

I also wouldn't be surprised if this was a cost-savings measure: it probably costs a lot more to R&D and produce a bespoke lightweight pulley, when you could just use the same one that your fleet of Imprezas/Outbacks/WRXs etc are using - especially when the difference is so marginal that people debate about its existence.

[Ernest72]

Originally Posted by Baldeagle

Sorry to bring up a potentially dead thread, but I just did some reading on this subject. It seems the OEM pulley is designed to quell certain vibrations. Assuming the internals of a boxer engine are balanced, it has no primary or secondary balance vibrations. (It does of course produce a rocking couple, which gives the flat four its notorious rumble.)

However it seems that at high rpm, an H4’s crankshaft incurs flex and that flex causes a vibration. The OEM two-piece pulley with the rubber ring is designed to absorb some of that vibration. If the rubber in the pulley were not present, the crankshaft’s bearings would absorb more of those flex-vibrations. Over time, that could increase wear on the crank bearings and reduce the engine’s lifespan. To what degree does this have an impact? I am clueless. But it seems there is a purpose for that rubber ring.

Over 80k on my 04WRX (143k) with lightweight pulley. Boxer engine is in great shape based on last used oil analysis at about 125k. I think abuse from other things will get the engine before the pulley. But either way the light weight pulley on the BRZ was not an earth shattering improvement, maybe a little faster rev. So do it if you feel like or don’t.