Light weight flywheel on EJ engine y/n?

[LeoneTurbo]

I'm into weight saving for my EA81 wagon and now looking at the EJ18 engine. It already has lighter pistons and rods, and I'm thinking about getting a lighter flywheel.

 

The stocker weighs 10.3 kg (ie. 22.7 lbs) and on Ebay.com there a few which save more than 10 lbs. I know that idle will probably be less stable and driving in traffic a bit more awkward, but does any of you have real life experience?

 

I'm looking at an XTR flywheel for an Impreza RS which weighs 12.55 lbs or ACT Streetlite at 13.9 lbs. The XTR is about 50 bucks cheaper (which it should be it is lighter afterall .

 

Any recommendations?

[GeneralDisorder]

This has been a recent field of study of mine - trying to buy a suitable flywheel for my EJ22 turbo. What I have found is that there is a some things to note besides just the weight:

 

1. *where* the weight is located is as important as how much total weigth there is. More weight at the crank's center is less effective at maintaining rotation than the same weight at the outer edge. Thus there is a lot of engineering that goes into a lightweight flywheel that is going to perform well in all situations.

 

2. Avoid the composite aluminium and steel units at all costs. These can and do suffer from catastrophic failure as they are essentially bolted together. Don't buy anything that isn't a solid cast chromoly flywheel.

 

3. The "super" lightweight models tend to affect idle quality and can cause clutch "stuttering" and other issues. It is best to stay around the 12 to 14 lb range. Any lighter and it causes problems for a lot of people (based on my research over on NASIOC, etc).

 

Being that there's a lot of engineering that went into the design, and making them work well in all situations..... my feeling is that the best product is the Exedy flywheels - they have the best reputation and they also make the best OEM replacement clutches - all the stock clutch components that I've replaced have been made by Daikin which is a subsidiary of Exedy. I settled on the Exedy flywheel and a stock WRX replacement clutch. The cost is only marginally more than the cheaper stuff....

 

GD

[WoodsWagon]

The nice thing about subarus is that if the flywheel disintegrates, the shards don't come into the passenger compartment. A lot of other cars have the flywheel inline with the drivers ankles, so when they frag, the pieces come through the floor and cut the drivers feet off. That's why SFI approved scattershields are required on high RPM drag race engines.

[LeoneTurbo]

Thanks for your input. I might get one of these but I'm still trying to justify the cost...

[renob123]

For somewhat similar benefits at a fraction of the cost/work, you could go with a lightweight pulley instead. When you finally do want to do the flywheel thing, you can sell the pulley. Don't do both.

 

Jacob

[Gloyale]

I'm into weight saving for my EA81 wagon and now looking at the EJ18 engine. It already has lighter pistons and rods, and I'm thinking about getting a lighter flywheel.

 

EJ18 and EJ22 rods and crank are identical.

 

Smaller cylinder bores, and smaller pistons. Can't be more than than 2 or 3 lbs difference in weight.

[LeoneTurbo]

I'm using the newer style pistons with coating and short skirt which are 74 gramms lighter - each! I'm also using Scat rods which are lighter also although I didn't weigh them.

 

I have a light weight, steel pulley off a EJ16 which weighs 600 gramms.

 

I guess I will just stick to the stock flywheel to keep driveability in traffic jams acceptable.

[cmill189]

I had a 9lb Fidanza flywheel in an old car (non Subaru.) It totally changed just about all driving aspects of the car, but mostly for the good. The only "bad" was the learning curve once installed, but it was really no big deal. Driving in traffic was hardly affected.

 

The biggest change was needing to rev match every shift, because the revs dropped as fast as they climbed. Just a blip of the throttle could take you from say, 3k to 6k, so learning to properly rev match was needed as well. With the A/C compressor engaged it was even more exaggerated.

 

It had a replaceable friction surface, so I don't if that counts as composite, but I drove tens of thousands of miles without issue. Idle was dead on, and there was no clutch chatter.

 

The pros FAR outweigh the cons in my opinion, however I can't speak for experience on a Subaru engine.

[tallwelder81]

HIJACK ALERT!!!!!

 

i want the lightweight pistons for MY ej18. mine is a 1994. cany anyone hook me up?

and just so i can claim i contributed to the thread, my 2 cents is that a super light flywheel is too twitchy. an engine hypothetically doesnt even need a flywheel to function. they put it there for some reason. it steadies the powerband and the firing order. especially in a boxer, the firing order is so UNbalanced, i dont think taking out the one part that was put in place to STEADY that twitchy power supply, should be tampered with or altered.

 

my 2 cents. im far from an expert.

[LeoneTurbo]

You can order the light weight pistons at your local dealer:

 

12006AA340 for grade A and 12006AA350 for grade B. Piston rings are the same for all EJ18E engines (1989-1998).

 

I'm using light weight high compression pistons (EJ16E) partnumbers 12006AA300 and 12006AA310 respectively. When you use these EJ16E pistons in an EJ18E block it takes the compression ratio up to 10.7:1.

 

Regarding the flywheel, the revs perfectly drop on up shifts with the original flywheel and I don't really want to do any rev matching on up shifts.

Edited August 14, 2011 by LeoneTurbo