theNeanderthol

iTrader: (1)

how do you guys have so much power in over 7000rpm? My '85 12A backs off after 6500rpm. What should i do to get power all the way through to 7000+? How high can i rev before its dangerous to the engine? Thanks

SilverRocket

I'm assuming you have stock exhaust? Well there's your answer. The stock exhaust system does not allow the motor to breathe sufficiently for good power above 6500 rpm or so. Go to headers and a high flow system and you'll notice much more power on the top end. Some kind of open air filter or cold air intake also helps out a little in this area.

Another reason could be lack of fuel on the top end - the stock fuel pump is not all that great.

I've also heard that the stock ignition system starts not wanting to keep up after 7 grand or so.

Everyone seems to say that the rev limit for a stock motor is about 8400 rpm. In other words, don't exceed 8 grand or so if you want your engine to last very long. It's not really necessary to rev that high anyways if you have a relatively stock motor.

XLR8

iTrader: (52)

Another major part of this is you have a stock port engine. Get a big street port or bridgeport and you will rev to 10. Don't understand porting? Go to Mazdatrix.com and they will explain alot. Happy Rotaring

theNeanderthol

iTrader: (1)

thanks guys do you think a high flow cat with a cat-back system could do the job, or is a header a must?

MarkPerez

An adjustable fuel regulator could help too.

SilverRocket

Unfortunately cat-back does next to nothing, the restriction is in the manifold and the cats. The first step to power on any FB is headers with presilencer/hiflow cat and good muffler.

You could probably just run a cat-replacement pipe with a hiflow cat, but I don't think you'd make much power without headers. Check out www.racingbeat.com, they make the best exhaust system for first gens.

peejay

Open headers and a better fuel pump!

The secret to my success...

Paul Yaw reports getting ~142hp out of a stock port, "optimized" stock carb engine, with a wiiiide powerband up to about 8000-8500. Exhaust is, believe it or not, the stock exhaust manifold and a 2 1/2" pipe. So with my open headers and slight porting job could get beat by a log manifold and a stock-port. Maybe next year...

AJC13B

Looks at intake and exhaust mods before looking at fuel setup.

Maybe get the secondaries on the carb welded open and a higher flowing air filter. If you can get a Paul Yaw carb conversion or a weber if money will alow.

As for exhaust for a stocker, get 1 7/8 primaries back to the drivers seat and into a 2.5 inch (at least) system, a muffler and resonator and then out. Get a cat and get it hollowed out and a pipe put through the middle of it (do NOT leave it hollow!).

That will give you quite a few more HP and more revs to play with

rx-7 crazy

this is some of the best advise I've heard ever one i know that has a fast 1 gen runs the racing beat exaust header-presilencer-upgraded muffler its $690 with shiping and handling but driving is beliving, thats the only up grade my friend has on his '83 and the differance between his and mine is wow, so mines on orded and should be hear in the next 3-4 days