annuerysm

is the S4 flywheel just not balanced as well as the S5? there is only a 3# difference between the two, (S4 NA =24#, s5 NA = 21# according to Mazdatrix) a 3 pound difference just doesnt seem to be enough of a difference to label the S4 flywheel a spinning timebomb at 8000 rpm. I'm just looking for some clarification on the subject I'm not sticking up for the crappy stock flywheel.

BDC

This is quite interesting. You guys in Japan seem to go against the common "expert" opinion here in the US (which tends to be the case with other things as well). Everything I've learned thus far about higher revs has to do with rotational balancing of the crank assembly, proper crank lubrication, and rotor clearancing between the adjacent end-plates. It seems to be there's either alot of misinformation and/or disagreement on alot of this. Of course, there's a disadvantage of both lack of people doing this kind of stuff (the average car dude doesn't dream about doing things like this let alone actually do it) as well as real, easy-to-see, quantifiable ways of measuring these kinds of changes. There's not many of us who'll modify an engine to this extent and then have before/after data to verify efficacy of changes. Even though I get alot of opinions and ideas from others, I tend towards practical experience as a way of measuring the worthwhile-ness of these claims (ala you guys in Japan and some in Australia).



The next motor I'm wanting to build for my FC (it will be engine #6) will be using:



- Series 5 block (J-Spec, around 45,000 miles on it to date)

- Series 4 turbo rotors (the 10.5lb, 8.5:1 CR rotors) milled to 3mm (old rotors I've used before)

- Race-clearanced rotor bearings

- Series 6 front and rear stationary gears and multi-windowed bearings

- Series 6 oil pressure regulator

- 2mm air corrector jets in the crankshaft for rotor oil jacketting

- Racing Beat lightened/hardened steel flywheel



... and other modifications such as the usual FD corner seal & side seal springs, better oil control ring and water jacket o-rings, etc. My goal is to redline at 9000rpms on a streeted, half-bridgeported engine. You can see from the above list that the general focus is on lubrication and (hopefully) dissipation of internal heat due to friction. I suspect that the higher you rev, the loads of friction places on the bearings and adjacent journals gemoetrically rises instead of linearly. Any comments about that are welcome and wanted.



For you mates in Japan, what do you think of this?



B

j9fd3s

it might just be due to the different ways the cars are used. in the states people want to have 100,000 trouble free miles and the way to do that is to be easier on the motor rpm wise, in other parts of the world they arent looking for 100,000mile engine life, dont have freeways and maybe use the car differently.



my tr3 is like that it turns 4000rpm at 80miles an hour, its miserable on the freeway for more than 10-20minutes, but its great on medium speed short distance stuff like you have in europe.



thats my theory on the subject, take it for waht its worth



mike

jspecracer7

You may be right Mike. I don't think about Gas Mileage, engine longevity or trouble free miles when I built my last motor. In fact, last motor I blew I took it apart, cleaned it up, bought an FC Oil Ring Kit, New Atkins Apex Seals and slapped it back together....since it had only 6000km's on it(blew it because I went lean...2.6 kilos will do that)



Basically, the engine has new rotor bearings and front/rear stationary gear bearings, oil control rings, corner seals/springs, side seal springs, apex seals/springs(this is before I blew it the second time).



Also built it for drag racing...how many U.S. FD's you know that have a 4.7 final gear?

j9fd3s

yah mines built so i dont have to pull the motor again, lol



mike

TheCamel

This is very obtainable, but longevity is the key. 2 years ago we all watched Scott and his FC do a lot more than 9000 on his half bridge, car ran for a full year, was NOT a daily river, but also revved it to 12,000 rpms. with 2 runs up to 15,000 (14,999 rev cut)all this on 1.3 kilo of boost, the car had over 4000 drag miles on it, the corner seal finally gave up and chewed its way into the end plate. Since then the car went through a complete transformation, body work, new Electromotive TEC III, fuel mods, and a bunch more, car has been on the road on and off since Dec 02 and 3 engines so far...

Dragon

Sure you will! BooM!

jspecracer7

I build all my motors with that in mind