bwomp969

how high can the 12a from a 1980 fb go?
I ask because the gauge cluster on mine doesn't work correctly.....I have no idea how fast im going after 85mph...
i dont think itll do 9 grand but the gauge peaks at 8 grand rpms and it hits the 8 grand mark and keeps revving(that was accidental i never go higher than 7 grand IF THAT high...because its an old motor and id like to keep it running and not destroy it
i ask because im just flat out curious i cant find it online.

edit: i was wondering is there a way that i could get a fd or fc's gauge cluster and install that in my fb? for a higher possibly more accurate mph and tachometer?

blackdeath647

iTrader: (2)

idk...but i was wondering the same thing yesterday after someone asked me lol. ..?

djessence

i dont think they limit do they?

Above 8500 on a stock motor (or lower) rotor chatter, water pump cavitation and oil issues start/are occuring.

Dont quite know where you are goin with this......

I mean technically the 12A motors can go beyond 10k rpm iof properly prepped.

bwomp969

lol

bwomp969

basically if i wanted to how high could i rev the motor before hurting it?8 grand? 8500? 9 grand? more?

blackdeath647

iTrader: (2)

(12a all stock, emissions removed)i knew they could just rev on forever lol, but like you said it all goes to hell at 8500 so, i guess it could easily spin 8k and if you only do it once, you'll be "ok-ish" considering that you might break an apex since they start to break off at like 7500 right? ...

the reason i asked this is cuz i was driving around with a friend, just showing him a bit of the 7, and a civic pulled up revving his engine, and i had to shut him up, so i almost redlined 2nd gear, (got up to 6700) i think its when my buzzer goes off and my friend just looked at me, asking of course what the buzzer was and i had to tell him that it was so i should shift, and he just asked me how far it could go w/out ******* anything up

Jeezus

iTrader: (4)

7500.

bwomp969

thankyou jeezus

PercentSevenC

7500 is the max I would ever take a stock motor with 3mm steel apex seals. Keep it to 7 grand if you care about the motor, especially if it is high-mileage with worn apex seal springs.

OneRotor

iTrader: (3)

i'd say 7k. Above 7500 you're looking at the start of seal chatter. somewhere north of 8k you're looking at shaft flex and possible contact between the rotors and irons. this equals blown motor. ask me how i know

grandgarson

Looks like you already have an answer to the RPM questions. As far as the gauge issue, I have part of an answer for you. The 1980 was the one year that the speedo was limited to 85 MPH. If you get the gauge cluster from a 1979 it will fit right into your 1980 and it has a 130MPH speedo. You can also go the other route and get a speedo from an 1981+. That is what the previous owner of my car did (I'm guessing they did that since they had a 1983 for parts. There are other things on it from a 1983, the engine and the bumper), the only problem with that is that they don't match the other gauges in the cluster. Here's a link to a thread that I started and the second picture on that thread shows what my gauge cluster looks like right now. I plan on swapping it out for one from a 1979 since I have access to 3 1979 parts cars.

As far as putting gauges from an FC or FD into an FB (although you don't have an FB, the 1979 and 1980 RX-7 are SA. There are many differences between SAs and FBs) I don't know if it would work, but I'm guessing that it would only work correctly if you were putting it into a 1984 or 1985 with a 13b since that is the engine that both FC and FD have, though the speedometer is really going to depend on the gear setup in the transmission.

mazdaverx713b

iTrader: (91)

anything much above 7000rpm and you are looking at apex seal chatter. this chattering will not only ruin the spex seals, but they can score the housing. there is no real need to go much past 7K on a stock port engine. the engine is not making peak power past 6K anyways.

blackdeath647

iTrader: (2)

here's another question, now that we can all agree 7k is a safe'ish' rev limit. How long could it run like this, for say just doing a pull, how much damage would it be going into the seals and engine, if let say you do up to 3/4th gear at 7k? i know they have to get hot if you constantly run it at that. then heat does all kinds of stuff...and yeah....


anyways, no i don't usually run my car hard, maybe once a month or so tops. and most of my shifts are about 6k, maybe hitting the buzzer (65/6700) on 1st/2nd gear.