humm... this is what i found some info that kiggly(kevin) post in dsmtuner & evom...
1. about bearing clearance & oil
If you're running 10w30 and not crazy power levels, you should shoot for near-stock clearances. In untouched DSM engines they were usually in the 0.002-0.0025" range. In the drag car I'm running 0.004" now with 25w50. I wouldn't want to try this loose of oil clearance on light oil though.
2. Mod wet sump
You can also fix all the oiling issues with a modified wet sump (i.e. - conventional) for more capacity by going deeper, a better pickup tube, and a windage tray. I have no oil pressure dips at all on the track and have logged this every pass for about 4 years. It is just now that I have everything sorted out to where I don't see some fall-off somewhere, just a constant 85-90psi. The center main bearing issue is not starvation or aeration. As far as I can tell, all our pump issues are oil pan and pickup related. If you run the pump without oil or with interruptions in the oil supply, it eats itself up. The honda engines definitely have a better developed oil sump/pickup system in OEM trim. This also takes its toll on turbo bearings.
3. Lighter parts
They wipe out center main bearings due to high bearing loads from a combination of light counterweights on the crank and heavy rotating parts. It may be possible to increase the counterweights to fix the bearing loads, but then all the bearing loads are very high. I'm attacking it from the lighter rotating parts point of view. I'm also trying some looser main bearing clearances this season to see if it helps. The bearing failure mode looks like overheating of the shells. At OEM clearances the center main bearing will be wiped out in somewhere around 20 passes.
4. Groove Main Bearing
A non-grooved center main bearing (like our OEM ones) would gall or wipe out in about 10 passes with my old setup. After grooving the main bearings they would go for a season. I think it is a bearing overheat issue, not a film strength issue. The slotted bearing flows more oil and cools itself better. I've been revving my 2.3l to 9k for several years now - you just need to add full diameter oiling grooves to the main bearings and they will live. 1/8" wide grooves, cut down to the bearing backing
5. Other info
- The main bearing issue is the lower center main bearing. If you run through all the combined inertia and cylinder pressure loading calculations you'll find this is the highest loaded bearing. The bearing loading is also tightly tied to counterweight mass. One reason I would be keen on checking out some of the aftermarket cranks is they could have a higher counterweight percentage to counteract the inertia forces at high rpm. I don't think the OEM 7-bolt has any strength issues, but I think it has the same inertia and bearing loading issues as all the 6-bolts.
- The problem with revving a 2.3l high is main bearings. This situation hardly changes at all between a 2.3l and long-rod 2.4l. For that matter, the piston acceleration advantage with the extra 6mm rod length is also very, very small. I didn't see anybody put any real numbers to this, but I believe it is less than 200rpm for the piston acceleration difference. Add the 6mm worth of extra rod length/weight and it is pretty much a wash. I see the only advantage of the 2.4l as the slightly lower rod angles for less cylinder wall wear, but with where the Wiseco stuff is going for skirt shapes the wall wear really isn't an issue.
- I've never balanced a crank, nor have I ever had any material cut off one. Its good to balance all the parts to each other, but as previously stated, they usually don't vary much at all. I just balance the pistons to each other and run it. I had several seasons on a 2.0l going to 9.5k like this and about 40 passes and 20 dyno pulls on a 2.3l going to 9k (other changes are req'd on a 2.3l at these rpm's).
- I've been spinning the 2.3l to 9200rpm for a little over a season now. The center main bearing doesn't love this, but lives if slotted/groove and seems to also like more clearance. The real fix is either more counterweight on the crank or less piston weight. I'm working with Wiseco on some parts to go higher than I'm going right now reliably. Then there is the issue of keeping it breathing up there...
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other supporting mod
1. kiggly HLA
2. install Main Bearing Cap Alignment Dowel
3. mod thurst bearing ( chamfer )
4. magnus dry sump kit... usd5000 huhuhu
fuu.. tired searching... but got some good info ...thanks google... huhuhu..
---------- Post added at 12:36 AM ---------- 6 hour anti-bump limit - Previous post was at 12:25 AM ----------
what about de-stroking it?
2.1 destroking.... that for who wanna rev to the moon... kekekeke
9000rpm can be done nicely with 2.2 & 2.0 setup ....
now i want fast spooling, nice torque & below 9000rpm rev.... 2.4 with nice build will be my choice.... or maybe 2.4LR can give me more safety margin.... huhuu..
