i_piss_on_hondas

Hey my tach doesn’t want to go any more past about 8300... Does this happen on all 1st gens or do I have a wiring problem or something??? The engine is revving past 8300 but the tach doesn’t... Forgive me if this is a repost... I posted a thread like this but it didn’t show up for some reason...

WackyRotary

The tac stops there yes, at least in both 84 and 85 models I have. Why are you reving that high? Do you have a bridgeport also? I never rev'd past 8Krpm unless I missed a shift with a mild or stockport. Bridgeport, perpheral intake porting that makes power peaks past 8000rpm nessessitating reving that high. Otherwise your just over-reving for no reason since your past the power peak a bit.

Mr_Rx7_Au

I was goin to say, I hope you have a PP or a Bridge Port, coz otherwise reving that high isn't really goin to do that much for ya...

specRX7_22

8300 rpm??? my god theres no need for that lol. i can see redlining it, but theres no reason to take it to 8300 lol

i_piss_on_hondas

I have street port... I am past my PEAK power but its still makeing more torque after 8k in 1st then it is in 2nd at the ground...

rx7 Nut

You might not want to rev that high, even with a streetport. And if the tach stops at 8300rpm how do you know when you've gone past 8500rpm(a no no).

MosesX605

I should think that you wouldn't want to kick the crap out of your engine like that. The gains don't outweigh the potential hazards. Without seeing your dyno sheet, I can't speak to your power curve, but with a stock motor's torque peak at 4k rpm, I find it unlikely that your motor is producing anything usefull at 8.3 k. Unless your engine builder balanced that eccentric shaft, it will be bending a fair amount at that kind of revs. Sooner or later, you'll get contact between a rotor and its housing and boom, no more motor.

Matt
1979 SA22C

i_piss_on_hondas

I live my life a rotary engine at a time and for those 10k miles OR LESS I am free I KNOW I have revved my motor past 8500 rpm... why is hat a no no? are you talking about water pump cavitation??? Its all about the gearing though... gears are torque multipliers... your generating ALOT more torque to the ground in 1st gear then 2nd at the same rpm... goes the same with the rest of the gears... I have a bad oil ring any way... Think I should make a custom aviator 1st gear 40 mph...

rx7passion

well i dont know if this is the explaination your looking for but the reason a tach doesnt go past 8300rpm or so is the design of the tach. i played around with a few 84-85 tachometers trying to get it to rev past the 8200-8500 mark. heres the reason, the needle follows on a horseshoe shaped plastic and metal track. there and 2 big stops the bottom where the tach sits at 0 rpm and round 8300 or so. you can cut the plastic/metal if your real carefull and dont bend the metal spiral that moves that tach around. that gets you to about 9500-10k rpm area. it can be dont but for the time and effort you might as well get a aftermarket tach thats accurate. hope that helps you out...

Directfreak

iTrader: (2)

Exactly. Unless your engine has the plates clearance for high RPM (I doubt it), there is a great danger of you E-shaft having a small flex at those RPMs. Then the Rotors would be slighlty out of alignment and really scratch, break, chatter, all inside of the Rotor's travel areas. - Basically, it becomes a worthless engine with no re-usable parts.

I strongly diasagree. The torque and HP curve on a 4-port is higher than 4K. On a Ported engine, it is almost a linear line, going up with more RPM.

High RPM revving comes to a point of diminishing returns as well. More RPM, doesn't equal faster than shifting at an earlier RPM.

Again, with the Rotor edges hitting the side plates, you're not going to be able to rebuild that engine. Shifting at such Higher RPM, the punishment takes it's toll on the whole drivetrain as well. Not to mention a shattering clutch at those RPM's can put you in a wheelchair without legs real fast. I think if you practice right, and learn the true HP curve of your engine, you'll see that approximately 7000 RPM will probably be a better place for you to shift.

Just looking out for you and your Rex.

MosesX605

Directfreak, do you have torque graphs for the stock port 12A? I was under the impression from the road tests I have read that torque peaked at 4k and dropped off thereafter. But, as I've said before and will say again, I'm no expert

Matt
1979 SA22C

pratch

And here I thought the meat of the powerband was about 5.5k-7k on a stockport. Please enlighten

i_piss_on_hondas

Well the block is pretty screwed anyway... Has a bad oil ring.. man u guys were bitching at me for revving my motor past 8k... I wonder what you guys would say if I told you about 1/3 of my oil is hyperlube to stop it from making a cloud that’s reminiscent of the nuclear explosion at Hiroshima

Mr_Rx7_Au

ahhaha, here we go again :P

Directfreak

iTrader: (2)

There's some Dyno sheets at the bottom. Both Stock port and street port.
http://personal.riverusers.com/~yawpower/strtcrb.html

By the way, for RACING, HP is more important than Torque.

851stgen12a

Urghhhhh

Felix Wankel

How's that, since HP comes from torque and RPM? Why do you think low displacement NA engines have to have the **** revved out of them?

Narcisse91

I think what he's saying is that for racing (not sure what kind), you're better off building up some top end HP then stroking the engine or adding forced induction to increase the amount of torque.

82streetracer

iTrader: (1)

i wound my old 12a to 8k at least once a day, pulled strong the whole way.

stock port with streetport exhaust and fuel and ignition upgrades.

i_piss_on_hondas

Hp is torque at rpm... a overall achievment of work done. I AM SHURE I was making more torque at 8500 in 1st then at 6000 in 2nd...