I keep hearing this. But to my understanding, that only applies to If your Motor Is ported.

Anyone have such fluctuations with a non ported motor?

For those with Ported motors, how much Idle fluctuation do you get?

Thanks

 

The definition of “idle” is relative. Any n/a engine that makes much more than 2HP/CI will not idle as smooth as a stock motor.
A light flywheel is a trade-off, more throttle response for less idle smoothness.

 

Most people have problems going from a high RPM to idle. The aluminum flywheel is so light, that when you let off the gas the engine RPMs decrease so fast (due to lack of weight and momentum normally given by the heavy *** stock flywheel) that the engine winds down to a stop. Some people adjust the TPS to get it to idle higher, some people trick the ECU into thinking the A/C is on. With the ECU thinking the engine is under load, it steps up the A/F mixture to keep the engine running.

 

i havent installed it on my fc yet, but when i had the 11lb fly wheel on my fb w/carb, i had no problems at all. even when i had the idle at 500rpm. it dose make the throttle response much better.

 

Good to hear Idle Is tamed on non ported motor. I believe that rpm's will plummet when letting of the Throttle due to the lightness of the Aluminum Flywheel.

Anyone else?

 

I've been using a 9.5# flywheel for over a year and have yet to experience any idle issues. My engine is stock ported '89 T2. It also has had the throttle body mod done to it, intake, full 3" exhaust, no accessories on it, emissions removed, etc. It's response is smart like a whip crack compared to what it was stock. No idle issues with the idle set to 800rpm. I have no idea what everybody is talking about when they say that the idle bounces around or even stalls out with a lightweight flywheel. Mine sure doesn't at least.

 

Same here on my NA stock port motor. Purrs @ 800rpm as well. Counterweights mix and match from all years, no?

 

I had an 11# aluminum flyweel on my old worn out stock port TII and there was no problem w/ idle fluctuation. Even when the idle dropped to 400 rpm after TID mod it was rock solid- at 400 rpm. Of course I bumped it back up to 750 rpm after 2 hours of Sears Point traffic jam...

 

I have my theories on these issues. They probably are not related to the parts themselves, but are pre-existing and are more pronounced with the lightweight flywheel. What I mean is that these issues stem from other maintenance issues that are not noticed with the heavy stock flywheel. But when it's off and the lightweight deal is on the issues are there. Sort of like all the issues that people have after they do the throttle body mod. Mine hasn't has any starting issues no matter how frozen the car is in the morning. I just made sure everything was good to go when I closed the hood after I did the mod. TPS set as close to perfect as I could get it (multimeter - don't leave home without it). All vacuum lines replaced and ziptied. So on so forth. I just don't seem to get these issues after I do stuff to my car. Beats me.


Just dig into your engine bay and replace just about anything made out of rubber if it's as old as the car and check all the sensor voltages to make sure they're OK and you should be able to avoid any problems. It's sometimes the little things that seem to be OK that make the car run less than perfect.

Hey, what else are weekends for anyways?

 

Yep, as soon as I got my old used up TII I spent alot of time and money putting all new rubber everything under the hood.
Much rubber was so brittle it shattered when dropped onto the garage floor.

 

The front counterweight, both rotors, and the rear counterweight make a matched set and should stay within the same years. There is a chart on Mazdatrix website that list what those years are. Click here and scroll down.

 

Excellent to know that at Idle you guys are not experincing any Ill effects. I asked b'c I'll be putting on a RB Aluminum Flywheel with my new ACT Xtreme Clutch/Pressure Plate and Street Organic Disk.

 

Wow you got yours off w/o it shattering? I had to take cutters and snip it off, the entire end on the vac lines just shattered.

 

Same here. Many of them stattered as I tried to get them off. Much of the remaining "rubber" was fused to the nipples and had to be chipped off gently to get them cleanly off.


And to think most people don't take care of this mundane stuff.

 

Well, the ones that just fell off the nipples shattered when they hit the floor. I also had many break as I took them off nipples.

My favorite was the fuel injector o- rings that were hard as rocks. The bottom ones fell off and broke, but the top ones had to be removed by scoring them w/ dykes and spreading w/ a little flathead srewdriver untill they shattered.

-edit- fuel injector air bleed socket o-rings that is...

 

My idle fluctuates within about 50rpms with a stock 24lb flywheel and my porting. I had it set at 750 when it was warm out and now it'll usually sit around 738 dropping to the high 600's and then bounce back up.

I'm looking forward to hearing how that setup works for you silverrotor. sounds similar to what I'll be running in the future.

 

I'll Keep you posted big dude.