20b rpm limits
09-23-13, 07:15 PM
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20b rpm limits
How high can you raise the 20b's rpms before a dry sump is needed then how high can you rev the motor with a dry sump?
09-23-13, 07:25 PM
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it depends. stock redline is 7k. if you put FD bearings/oil pressure and have factory balance of better, maybe you go to 8?
the competition 3 rotor was rated at 8500 instead of 9000 like the 12A/13B, so maybe 7500+ you should be thinking about a dry sump?
the competition 3 rotor was rated at 8500 instead of 9000 like the 12A/13B, so maybe 7500+ you should be thinking about a dry sump?
09-24-13, 11:34 AM
#3
dry sump has nothing (or at least not much) to do with redline.
The purpose of a dry sump is to avoid lubrication problems at high acceleration levels, where the oil can be pushed to the side of the pan and expose the pickup. A dry sump uses a smaller, deeper tank to increase the angle the oil has to reach to cause pickup issues.
Many people (including myself) rev the 20B to ~8500RPM with no issues. The limit is eccentric shaft flex, so any higher than that and you need balanced/lightened rotating assembly and/or a 4 main bearing setup.
The purpose of a dry sump is to avoid lubrication problems at high acceleration levels, where the oil can be pushed to the side of the pan and expose the pickup. A dry sump uses a smaller, deeper tank to increase the angle the oil has to reach to cause pickup issues.
Many people (including myself) rev the 20B to ~8500RPM with no issues. The limit is eccentric shaft flex, so any higher than that and you need balanced/lightened rotating assembly and/or a 4 main bearing setup.
09-24-13, 09:45 PM
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maybe a 3 piece e shaft with a bearing in the rear center iron like what is used with the two piece 13b e shaft.....https://www.rx7club.com/attachments/...sc04090bi1-jpg
https://www.rx7club.com/attachments/...sc04089iy3-jpg
https://www.rx7club.com/attachments/...sc04089iy3-jpg
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09-26-13, 11:00 PM
#9
Actually stock redline is higher than 7k. It's only 7k because of the auto torque converter. The fd auto is lowered for the same reason. Logans testing claimed that the stock oil pump doesn't start loosing pressure till about 8,500. Anything higher than this requires clearencing, drysump, rebalance, ect. I have my soft fuel cut set to 8k with full cut at 8,500k for this reason.
10-15-13, 09:13 AM
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I have to wonder why no one has made an upgraded oil pump another that wold allow you to retain the stock wet sump if you wanted and go to higher rpms
10-15-13, 07:32 PM
#11
I have my rev limiter at 8700 RPM and do use it on occasion. FD pressure regulator and race bearings. Opening the motor this winter to fix a suspected coolant seal leak so I'll have a look at the bearings which were all new.
The stock upper doesn't really make power over 8k so your not really doing anything up there anyway.
thewird
The stock upper doesn't really make power over 8k so your not really doing anything up there anyway.
thewird
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