Hi,

I have had my 83 rx-7 for about a year and the other day the transmission started to be harder to shift into gear, esp 1st and 2nd. Also my car has 147k on it and a new motor that doesn't leak oil would be good.

I have decided that i want to get my motor or another rebuilt. I was wondering if anyone knows how much hp a ported 12a can get? also is it street legal? I have though about turbos but ports seems to be better.... And how about a 13B? im hoping to get my car to put out 200-250hp...

Also will another 12a tranny bolt in and be able to take the HP or should i get a gsl-se or t2 tranny..(is it possible?)

Thanks, any thoughts are greatly apperciated

 

For the most part, the legality of street legal depends on what state you live in. Here in South Dakota, You can run a Chevy Nova with a Tunnel Ram intake, dual carbs, headers comming out under the fenders with flames shooting out, as long as you can keep it at the speed limit. All N/A tranny's mate up to all N/A engines. I'm not sure, but I think a turbo tranny will bolt in to a N/A engine. I know the turbo engines have a flywheel that is slightly bigger around so you have to check to make sure the trannys will work. If you want HP, port the engine, run headers (check Racing Beat, they have a couple different set ups for street ported engines) with high flow muffler using something like 2.25" pipe between, do away with the air pump after you get the headers, run an electric water pump, electric fan, and get the under driven pulleys for the altinator and main shaft. Also get a steel flywheel (racing beat, or Mazdatrix). The stock flywheels are about 30lbs, the steel ones are 17, and most of the weight is close around the center hole, not out toward the edge. They have aluminum flywheels that weight about 9lbs, but they make street driving tougher, especially starting out in 1st. Put those mods together and Dyno test your car. Get a cool air intake for the carb too. The more cool, unobstructed air flow you can get, the better.

 

That still won't be anywhere near 200 hp.

 

Felix is right. The stock carb won't come even close to cutting it on a ported engine. To make any decent power you need to modify the hell out of the four barrel or run a Weber/Dellorto.

With an IDA Weber, street-port 12A, and good exhaust you might get close to 200hp. Most probably around 180hp. To get any more you'll need to bridge-port the bitch.

 

If i were to have a good carb, and header and a steert ported 12a...along with the high flow cats and muffler i already have, what kind of hp do you think i would be looking at. Also does street porting lower engine life?..what kind of life time can i expect? And if i bridge port what Hp am i looking at and life exceptancy?

Also with a 12a tranny take the hp?
or are there any 13B trannies that will bolt in?

Thanks

 

sorry, are those hp estimates at the flywheel or the rear wheels?... basically i want my car to be able to do 0-60 in 5.5ish, how much hp at the rear wheel or fly wheel do i need?

 

12a trannies can handle upwards of 300hp and all the torque our little n/a motors can put out. Turbocharging is another story.

185 flywheel hp is doable with a good 12a streetport, good carb and free flow exhaust with some MSD to boot, and of course well tuned. 0-60 in 5.5 ain't gonna be easy with this motor without gutting the interior and tossing extra weight from everywhere.

I might have some 12a streetported housings and motor accessories for sale in a week, but it'll cost a lot more than 1 dollar.

 

drivefast7 i might be interested...maybe, but i live in NH and you are in CA can't imagine cheap shipping...

 

You can break a stock tranny with a N/A 12A! It all depends on how much traction, how much clutch, and what kind of driver are in the car! (One tech writer is fond of saying you can break any transmission with just a lwenmower engine.. and he's right!)

With a soft clutch and weak traction and a careful driver, you can make the stock trans last for a while. Put on a puck clutch and sticky tires and you can break the transmission the first time you launch it.

As for 0-60 in 5.5... Time to speed isn't a very good deterimation. Think about this extreme example - a car accelerates to 55mph in .1 second and then takes an additional 4.9sec to get to 60mph. (0-60 in 5.0 seconds) Another accelerates to 5mph in 4.9 seconds and takes only .1sec to get from there to 60. Both cars to 0-60 in 5 seconds. The first car will have traveled a LOT more distance in that 5 seconds, though, and would have won a distance race. This illustrates that it is most important to make the slow parts faster, instead of making the already-fast parts faster.

So time to speed means very little Your best bang for the buck will be shorter rearend gears. That makes the slow parts from a standstill) faster.

 

1 dollar, check your pm. Shipping to NH won't be all that much since it's parts and the rotor housings are aluminum afterall.

peejay, my friend with the 285hp doesn't drag race. he does real racing - road racing aka circuit racing. Drag racing puts all kinds of abuse and shock loading on the trans. but, of course no one here would ever abuse their trans!!!

bradP

 

I figure all racing is "real" racing - road racing, autocrossing, drag racing, it's all competition and all about finishing first.

Drag racing's cheaper to start out doing than road racing but it costs more in the end...

 

peejay, i have an 83 5spd, so that means i have 3.9? rearend?, as it is now, on the highway 60 mph is 3000rpm, im not planning on driving it on the highway much, but when i do i need to be able to keep up with traffic ..70 mph. So i don't think different rear gears would work out, would they?

 

Downshift