what do I need to do to safely spin 8000 to 8500 rpm.
02-28-02, 06:48 PM
#1
what do I need to do to safely spin 8000 to 8500 rpm.
I would like to increace power by increasing rpm.
I am thinking 8 to 8.5k. '
This is on a 82 with a streetport header/presilencer apexi n1 muffler. soon to have a holley kit and streetport.
thanx
I am thinking 8 to 8.5k. '
This is on a 82 with a streetport header/presilencer apexi n1 muffler. soon to have a holley kit and streetport.
thanx
02-28-02, 07:29 PM
#2
Old [Sch|F]ool
Never ever go over 8500.
Don't go over 6200 for more than a few seconds at a time.
If you want sustained revs over 6200, or over 8500, get carbon-aluminum apex seals (the jury is still out on the hurleys), hardened stationary gears, pinned rotor gears, upgraded oil system (GSL-SE oil pump setup and high-pressure regulators), windowed rear man bearing... basically everything in the RB catalog.
Although people've told me that there's no real need to pin the rotor gear. Would you chance it?
I ran my stock internals engine up to 8400 all the time in a drag racing environment. On the road course I kept revs imn the 6000-8400 range, and it ran hot because I was still running the stock pulleys - this overspeeds the water pump and causes it to work rather poorly. The one time I revved it past 8500...
Don't go over 6200 for more than a few seconds at a time.
If you want sustained revs over 6200, or over 8500, get carbon-aluminum apex seals (the jury is still out on the hurleys), hardened stationary gears, pinned rotor gears, upgraded oil system (GSL-SE oil pump setup and high-pressure regulators), windowed rear man bearing... basically everything in the RB catalog.
Although people've told me that there's no real need to pin the rotor gear. Would you chance it?I ran my stock internals engine up to 8400 all the time in a drag racing environment. On the road course I kept revs imn the 6000-8400 range, and it ran hot because I was still running the stock pulleys - this overspeeds the water pump and causes it to work rather poorly. The one time I revved it past 8500...
03-01-02, 05:17 PM
#5
smog nazi destroyer
take the same advice on those..
no higher than 6500 for everyday driving with around 8500 for racing.
that is really the safest way to go.. it minimises cracking the stationary gears
no higher than 6500 for everyday driving with around 8500 for racing.
that is really the safest way to go.. it minimises cracking the stationary gears
03-01-02, 06:34 PM
#6
Hunting Skylines
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I really don't think there's much chance of cracking a stationary gear on a stock motor even by going above 8500rpm. It's more of an apex seal issue. But there's really no need to go that high with stock ports anyway as peak power is below 7000rpm. Even with my extend-port the highest I ever go is 8000rpm.
03-01-02, 08:16 PM
#7
standard combustion
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Theres no need to sustain over 6500rpm unless your trying to top it out. If your hp peek is at 7500rpm. 1st Gear shift point is probably 8100rpm<-estamate only. Every gear after that should be closer to 7500rpm. Build your engine for your HP peak, because you will not go beyond it except in 1st and 2nd and maybe 3rd gear. After that time sustained above the HP peak is a waste of your engine. Does your engine peak past 8500rpm for its HP peak....likely not.
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03-03-02, 10:16 PM
#10
Old [Sch|F]ool
Stock apex seals start to chatter over 6200rpm. They lose contact with the rotor housing and float/bounce. This is similar to valves floating on a boinger, and the effect is similar - it weakens the springs and eventually will damage the apex seals and rotor housings. It doesn't become a significant problem until over 8500, but it's still a good idea to stay out of that RPM range for sustained periods.
Also, with the stock pulleys, the water pump starts cavitating over about 6000-6200rpm - small pockets of vacuum/water vapor form behind the impeller fins. This obviously is no good for cooling.
Mazda knew all this. The 3mm-seal engines lose power over 6k because of port and exhaust restrictions, and the 12A engine's carb circuits go way overrich over about 7000. Mazda wanted the driver to see no point in exceeding about 6500 and shift up by then. There is no gain in running a stock 12A up really high, in fact you get your best acceleration shifting just past power peak (6000rpm). All the engine does after that is make noise.
Also, with the stock pulleys, the water pump starts cavitating over about 6000-6200rpm - small pockets of vacuum/water vapor form behind the impeller fins. This obviously is no good for cooling.
Mazda knew all this. The 3mm-seal engines lose power over 6k because of port and exhaust restrictions, and the 12A engine's carb circuits go way overrich over about 7000. Mazda wanted the driver to see no point in exceeding about 6500 and shift up by then. There is no gain in running a stock 12A up really high, in fact you get your best acceleration shifting just past power peak (6000rpm). All the engine does after that is make noise.
03-03-02, 10:57 PM
#11
standard combustion
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Exactly as PeeJay put it. Stock engine. LOOk at its peaks....Hp 101@6000 TQ 107@4000. There is no reason in a COMPLETELY STOCK ENGINE to exceed 7500rpm in first so every gear after that will be closer t0 6000rpm except at 4gear at 115mph when the power is close to the same as 5gear at a lower rpm which is another story of aerodynamics vs avaible power at that speed in which gear your in.
03-03-02, 11:23 PM
#12
Old [Sch|F]ool
7500? If I was in my stock 12A and you were in your stock 12A and we took off at the same time, and I shift to 2nd at 6200-6500 and you wait until 7500, you'll be seeing my taillights!
03-04-02, 03:55 PM
#14
where are you guys seeing COMPLETELY STOCK in my post.
My car is streetported with a custom RacingBeat long header exhaust. Plus I plan to add a holley carb. That has got to have power above 7500. Can I swap out the apex seals for better ones for reliability.
My car is streetported with a custom RacingBeat long header exhaust. Plus I plan to add a holley carb. That has got to have power above 7500. Can I swap out the apex seals for better ones for reliability.
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