Well, the Agency Power underdrive pulley seems to be a pretty hot ticket but how do underdrive pulleys compare with lightweight flywheels? Essentially they do the same thing, let the engine rev faster which allows better throttle response. My question, however, is what are the greater differences? I understand with an underdrive pulley you will have lower power at lower revs (poor ac :/) and I understand the idle is a bit rougher with a lightweight flywheel. Does the better responce of the lightweight flywheel negate the $150^+labor price difference (AP pulley = $145, ACT prolight=$360+labor)?

Simpler question: Is the performance of a lightweight flywheel worth the $$ when compared to an underdrive pulley system?

edit: Oh, and yes I'm aware neither really add significant (if any) hp/torque - the throttle response/faster revs are all I'm looking for

 

Simle answer - yes .
Flywheel is the single most effective mod you can do short of F/I .

 

flywheel is the way to go. underdrive pulley is not for everybody. ITs for people who does not even use their electronic stuff at the fullest. A/C is just one of them.

 

they are all good choices. i mean the pulley is good for the price. but the bad thing is the ac and energy decreases in car( like headlights and system if you have one) the flywheel is good. everyone seems to point to the flywheel but it is pricey. if you have the money, go for the flywheel. if you dont, go for the pulley.

 

Pulley will help things down low and up top, down low it will give more power to the engine instead of having it struggle against the accessories, and up top it allows the water pump and alternator to run more efficiently because it doesn't max them out.

Flywheel does the exact same thing essentially, but the only difference is that by lightening the flywheel you don't underdrive anything.

That and the only time there is any a/c or energy issues is when the car is at idle, while your driving around there are no problems whatso ever.

Took the pulley on a 3k roadtrip to 100+ degree texas and the a/c was frosty and delicious, except at stoplights, but by keeping the idle at 2k I was in the cool.

They are both steps on the way to a sweet car.

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/agency-power-underdrive-pulley-review-pics-90310/

https://www.rx8club.com/showpost.php...3&postcount=91

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/post-recall-dyno-today-99812/

 

this is correct.. but the install is not cheap.. as to the pulley the jury is still out on that one...

beers

 

Well i don't know what adding a pulley feels like but I just added the Mazdaspeed Flywheel and love it. A couple weeks before I got it, my buddy with an 02 WRX (no mods) wanted to see how our cars compared. With a roling start on an open highway we floored it, I pulled ahead just a bit right off the bat, but then we were pretty much even the whole way after that. No car pulling on the other, I might have inched forward a total of 1 foot but that's it. We did this 3 times, same result.

So I get my MS flywheel installed and we went at it again 2 nights ago. Well what do you know? As soon as we punched it I pulled away faster, but then instead of staying the same like last time, I just kept pulling away steadily. Only did it twice but it was the same both times. Needless to say, we were both pretty impressed by those extra wheel HP due to the light weight flywheel.

There is a little hint of rough idle once in a while now, but that's it. The car starts faster when you turn the key, revs up/down faster, and is more fun. As for everyday driveability (i.e. in traffic/city), I don't really notice any difference.

 

Changing the flywheel will not give you any HP increase. It just going to get to the rpm faster.

 

I love it when people say this.

 

Mazda Motorsports also suggests underdrive pulleys for another reason - engine cooling. It seems that above 6500-7000 rpm, the water pump starts cavitating, which significantly contributes to overheating. Changing the water pump pulley improves cooling at higher rpms. They also say that an underdrive alternator pulley will result in a longer life for your alternator.

 

thanks for the info... justification for buying another mod...

 

I just installed the Agency Power pulley this past weekend... it took all of about an hour to do at a very slow work pace. Everything can be done with some socket wrenches, an extension, and alumn keys for the new bolts on the AP pulley.
The difference?
Like everyone before me stated, there is a noticable gain in the bottom end pickup, feels like the engine doesnt have to try as hard to get the car rolling, and at the top end the revs seem to peak a bit faster. Biggest difference Ive noticed is in spirited shifting, the revs seem to pick right back up with each shift, no bogginess at the bottom end of second and third.
I was in between getting a new flywheel and getting the AP Pulley, but the difference in initial cost and cost of installation (AP Pulley= DIY/ Flywheel=$$) had me do the pulley first. Im sure ill put the flywheel in before the newyear though.
Cant wait to have them both on the car... I hear the revs come up mighty quick with a flywheel/pulley combo.

 

Well why do you think it rev's faster then?
It doesn't give you more crank HP, but does give you more wheel HP due to less power loss from the engine to the wheels. It's not a lot but it's noticeable.

 

Thanks for the help guys! I figured a lightweight flywheel didn't necesarily give more horsepower but allowed the engine to reach where it makes more hp faster - giving the feeling of more hp.

Anybody know what kind of $$ I'd be looking at for a flywheel install? Agh, I was initially just going to wait until my clutch was gone but having extra $$ and reading the topics is getting to me!

 

Go have a dyno run before/after flywheel change.

Actually, there are quite a few up here. do a search.

 

Well since I'm not going to uninstall my new flywheel and put my old one back on to dyno it I guess I'll look up some dyno sheets. You may be right. However, the fact that now I'm faster than my buddy's WRX after the flywheen install, is good enough for me.

Oh yeah the new flywheel is great for Heel-Toe downshifting, can't wait for the next track day. Peace.

 

I've done both mods, and you get what you pay for.

The flywheel has been the best mod to my RX-8, which was done 1-1/2 years ago. The Agency pulley was done a couple of months ago, and it did help some on building the revs faster in 1st & 2nd gear.

 

Great ! pwn all those suba*nubs* out there ! :D

 

Do the AP pullies really dim the headlights? I haven't heard of them affecting anything besides AC (and aftermarket sound). I have the HID lights. Does anyone know if those would be affected? If so that would be a deal breaker for me as I love bright headlights.

 

yea. they will dim them a bit.

 

Do you even have the pulley?

No, nothing dims at all.

 

please can we have more clarification on this as Im with Limpy..... I like bright headlights too.....

 

In the 2K miles I've had mine installed, the AP pulley doesn't dim your headlights or make the A/C feel warmer.

 

cheers.... any more opinons?

Im about to order the pulleys and flywheel.

But headlight dimming is a deal breaker as i said above....

 

I cannot offer any opinion, as I have not driven at night since the pulley install.