DeAd-EyE

iTrader: (1)

What's the point, what advantaged and dissadvantages are they. I mean it's louder, more stressful on the engine and i heard ur HP drops... so, yeah...why?

Bridgeported

Depending on your engine configuration, upping the redline generally allows you to make more power, and also gives you a broader powerband so you always have full power to keep accelerating.

In some instances though, like you mentioned, it won't help and you might actually drop in power.

DeAd-EyE

iTrader: (1)

with an upped redling... le's say 9 thousand i guess....10000 would proably be way too harsh for daily beater

would u have to switch to a single turbo?

rynberg

With a stock-ported motor, there is no point in exceeding 8000 rpm, even with all the bolt-ons. On a close to stock car, the power peaks at 6500 rpm and starts dropping off pretty hard after 7500 rpm. A street-ported motor may make it worthwhile to exceed 8000 rpm. Note that exceeding 8000 rpm is probably not that smart with an unbalanced drivetrain (even though jspecracer7 hits 9k in 1st gear all the time....).

suprfast

i dont remember where i heard this but or if it was for our rotaries our the honda motors. i was told that going from 8000 to 9000 rpms would double the stress put on the motor. if you dont make power and dont want to ruin it, dont take it up that high. i take mine to about 7800 rpms but i dont always have time to shift in autoXes. yes, i redline my second gear in autoXes. maybe for you draggers, taking it that far means one less time to shift. dont know much on the time it takes to shift versus the time it takes to leave it in gear and lose power controversy so i wont get in it.
kris

DeAd-EyE

iTrader: (1)

so basically the general conscensus is that unless you've got a nuts amount of HP, I.E. 500+ there's no point in doing what appears to be a really expensive and innefficient mod.

suprfast

wrong. it doesnt matter if you had 1000 HP or not. it depends on how well the engine breathes. porting the motor extensively is the only way to bump up the rev limiter, just as throwing in a larger cam for a piston motor. with all upgrades all safetly measures must be taken care of. if you throw in a big cam, you must put in stiffer valve springs/ retainers and the such. if you port a rotary you must...i havent a clue but i know you cant just port it. maybe fuel
kris

2a+RoN

yeah, i was just wondering what all safety mods you would need to run an 8000+ motor. Are just fuel mods sufficient?

93redFD

no, I think it need more than just fuel. I have heared of peeps blowing motor by over reving. I dont know what it tears up inside the motor though.

kkekeisen

One of the things that makes the rotary so great is its willingness to rev. the only way you will blow it up is if you don't hvae the fuel capabilities to support the more fuel required @ higher revs. However, if you plan on revving highly on an often basis, it is adivsable to get your drivetrain balanced.

DeAd-EyE

iTrader: (1)

drivetrain balanced? what does that mean.. (sorry..i'm not technically knowledgeable.. still trying to learn stiff)

suprfast

that means taking everything out that is part of the rotational mass(including pulleys) and putting them on a balance. then it will mark points that either weight needs to be added or removed. it will be similar to balancing a tire if you must
kris

Beast From The East

Ok, gang, before you go upping your rev limitters to 10K and merrily spinning your motors into oblivion, think before you leap. First, do some math:

8K rpm (normal redline) = 133.3 revolutions/second, so one revolution = .0075187 seconds (7.5187 ms)

10K rpm = 166.6 revolutions/second, so one revolution = .0060024 (6.0024 ms).

So, at 10K rpm you have 1.5 ms less time for 'things to happen', such as spark, fuel delivery (opening and closing a fuel injector), etc. The stock components responsible for that sort of thing are not equipped to deal with that.

I'm not a hard-core physics student (I have not taken a physics class in ..... well, let's say 18 years or so), but I remember enough to know that the rotational inertial forces that the eccentric shaft is subjected to is some sort of log or expotential function, and after 8K rpm the shaft begins to 'flex' under the force of the rotors spinning over 8K. At 10K (on stock components) - kaboom go your internals, as your rotors begin to actually hit your housings due to the shaft flexing (minutely, but enough considering the tolerances a standard motor is built to). This is why there are special lightened rotors available from Mazdacomp - they spin easier and put less stress on the e-shaft. This is also why the big guys (Ari, Pac Racing, etc) custom build their motors to specs most of us don't use or need.

Anyway, I'm just a newbie at this still, but think before going much beyond the stock rev limit unless you have the equipment to handle it. Think about water pump cavitation, the ability of the oil pump to handle the extra needed pressure, etc. I don't know if those components are equipped to handle the load, either. Check other threads on this board from REPUTABLE people who have a history of success at the race track.

Beast

HEVNSNT

iTrader: (3)

ITS ALL ABOUT AIRFLOW

The easiest way (in theory) to increase engine output without having to increase boost pressure or displacement is to increase the redline.

HP=[torque x rpm] / 5252

FD stock at 255HP@6500rpm is producing 206ft/lbs of torque at the same rpm.

If (and I stress IF) you can increase the redline to 8K rpm while producing the same torque at that rpm then you will get: 314 HP. Thats an increase of approx 60HP from just raising the redline.

Now comes the IF:

There is a direct relation between fuel consumption and torque. Fuel consumption peaks at the torque peak.

"Power" comes from the mixture of gasoline and air. This mixture must go into the engine at the right proportions. Meaning if you can stuff more air into the engine then you can stuff more gas into the engine, and buy stuffing in more of both in the right proportions the engine will create more power.

The reason why power tends to drop off near redline is because the engine wasn't designed to "stuff" in much more air at those rpms and hence cannot "stuff" in more fuel which decreases "power". Buy porting a motor you are essentially "stuffing" in more air at higher rpms which allows you to "stuff" more fuel. More air + more fuel at at higher rpm means significant increases in power output.

So lets say you were able to increase the 206ft/lbs@6500rpm to 250ft/lbs@8000rpm:

380 HP!

So how much more air is needed to provide an increase of 44ft/lbs to 8000rpm instead of 6500?

Theory does not always apply in the real world. These power increases must also overcome increased frictional losses, inertial losses, etc, as some already mentioned. Then there's the mechanical side of balancing and so on......