jeremy

iTrader: (1)

true, but i would put neither in a drag car

riffraff

so how much can the stock **** handle? tranny, drive shaft, clutch... right now i have somewhere around 200 hp in my 79 (tranny, clutch, and drive shaft are off of my old 80) so it is not that much of a concern. but if i start to increase the power more (which i will) i know i will need a new clutch. what about the tranny? etc?

peejay

I theorize that if you upgrade the clutch the tranny will blow. I also theorize that the '84-85 trannies are garbage because they have smaller teeth on 3rd and 5th gears. As such, when I put a new clutch in my '85, I'm also going to be putting my '80's trans in it. The bearings in the current tranny are pretty noisy, anyway. (sounds like a coffee grinder full of metal shavings )

riffraff

so what options do we have for other tranny's then? will a TII tranny bolt directly up to my 78 rx4 13b?

peejay

I think that's something search-worthy.

I do know that the bellhousing bolt patterns are the same for all rotaries, so the trans will bolt to the case, and they make a special clutch disk that is N/A sized but has the T2 input splines, after that I get fuzzy

riffraff

hmm.. oh well, no need to worry about that now.. hopefully i have a ways to go before i need to worry about replacing the clutch and tranny

85RX7GS

iTrader: (1)

What about all this porting business? Since I am going to get a rebuilt 12A soon, should I get it J-ported, street ported or bridgeported? I really don't know what the difference is between them all, but I do want my rex to be fast and more 'torquey' (not a word, but you know what I mean) off the line. I want it to sound cool and have more horsepower, without changing to a 13B. I'm also going to be driving this back and forth to school (1hr), occasionally doing some racing and such... Any suggestions?

Defprun

My 1984 GS has the 12a, no A/C (including the condensor) no power windows no cruise control but has, Manual Steering, LSD and Automatic Transmission and a aftermarket sunroof that seams lighter that factory. It comes with a case so I can always take it off though! I plan on gutting the interior of insulation...the clunks and bangs and squeels all appeal to me. I'm going to take out the factory amps and other crap like that pesky spare tire!

If you want power from a 1st gen, visit mazdaracing.com. They have a 1st gen with stock 12a and transmission (from a junkyard!) with a custom turbo kit on it that beats cars with 302's in them! I watch the video a couple times a week.

peejay

If you want to see cool video to to mazdaracing.com, just don't try to buy anything from them.

That car only does high 11's BTW. Not enough to beat Mustangs. (They feed 'em with super oats 'round here )

riffraff

85rx7gs: if you are going to be doing some 'real' driving, commuting type thigns, then you might want to stay away from the bridgeport.. i am not exactly sure as to what a j-port is, but a nice streetport is always a good option.. it will not be to loud, have some power, not kill your gas milage (like a bridge port will) and will last longer than a brideport.

peejay

J-bridge is a bridge port so large that it extends into the water jacket. (Jacket bridge) Apparently they only last about 6 months before they leak coolant into the engine, since you have to cut away the water seal where the port is.

NOTA V6

Sorry for the late response. My e-mail notification is evidently out of commission.

The GSLs came standard with most of the stuff that comes on the SE, so what is the point to getting the GSL as a base? The same options minus what? The 13B? The parts needed for a transplant? If that is even an option, there has been no indication form the original poster as to his purpose for wanting this 300 hp lightweight monster...

NOTA V6

Weight is weight. If you are reducing weight, 2 lbs. here, 5 lbs. there, 3 lbs. another place = 10lbs.

Does a 13B flywheel and counterweight weigh more than a 12A's flywheel and counter weight or not? I don't knoiw, but I would guess that they might.

peejay

Depends on the year.

NOTA V6

In a race car, anything that is not intended to make the car faster or handle better is dead weight. In a street car, some of that fat you mention becomes desireable, like a radio, or AC. So, what is the original poster's intention?

NOTA V6

Is any year 12A flywheel and counterweight heavier than a GSL-SE 13B flywheel and counterweight? I can't believe this has become an issue to debate. It is a minute point in the much larger arguement for using a particular platform to build upon toward an unknown performance goal...

peejay

NOTA V6, that's exactly my point. I wouldn't worry about a pound or two or rotor and counterweight weight in determining whether to run a 12A or a 13B. 12As and 13Bs have the same port sizes and so would make about the same peak HP, but the 13B would have a broader powerband due to its larger displacement and would therefore be faster overall. Certainly it would negate a pound or two of rotating weight.

I have no clue as to the original poster's intention... he wants to know if a stock car will make 300hp? If you modify it to make 300hp it will be very very far from stock, so stock form is really a moot point.

peejay

From Mazdatrix's website:

13B Rotor Weight 74-85: 11.58 lb (compression is higher '84-85 but they weigh the same)

12A Rotor Weight 76-82: 10.15 lb

13B Rotor Weight 86-88: 10.04 lb (compression different turbo vs. non but weight's the same)

12A Rotor Weight 83-85: 9.60 lb (now you know why I like late 12A's )

13B Rotor Weight 89-95: 9.54 lb (compression different turbo vs. non but weight's the same)

We can assume that counterweight weight is relative to rotor weight. The difference between the lightest and the heaviest is roughly 2 pounds.

peejay

Flywheels from Mazdatrix's website:

'79-80 12A: 30 lb

'86-88 13B: 27 lb (Turbo)

'83-85 12A: 26 lb
'84-85 13B: 26 lb (GSL-SE)

'86-88 13B: 24 lb (Non-turbo)

'81-82 12A: 23 lb
'89-92 13B: 23 lb (Turbo)

'89-92 13B: 21 lb (Non-turbo)

'93-95 13B: 20 lb (obviously, Turbo)

Of course none of this matters if you go to a lightweight flywheel.

NOTA V6

Stock form is the platform to build on. If you start with more, you can remove it a lot easier than starting with less and installing all the other gear you need or want. My goal for instance is 300+ hp. With the flick of the switch (Wolf map), I can have a 500 hp time bomb. I will still run AC (although not when racing or pushing the boost limit), sound insulation, and a radio with cassette player. No racing seats. No lexan windows. My goal is street performance with occasional track time of a less competitive nature.

Like I say, weight is weight if choosing it as a stock platform to build upon. With the 300 hp 12A or the TII transplant, the stock flywheel and counterweight from either platform is leaving. The argument I was pursuing is that the weight of the GSL-SE stock as opposed to the 12A models stock is not completely options. However I see that my flywheel argument is shot down. Thanks for the research.

If the original poster is going for a race car, then he's better off checking the regulations first than asking us. If he's going for street performance, IMHO he's better off starting with the SE and whittling away, and/or going turbo, which the SE would facilitate, since a 300 hp 12A would not be reliable, or very streetable.

We need a goal from Aico before any of this theorizing will do any good. Aico?

NOTA V6

peejay: You should come to the MRR. Link below...

peejay

No way! That's the weekend of the Sport Compact Nats at Norwalk. I need to see if I can make it past the semifinals in Bracket 3 this year.

Besides... I'm not a fan of car shows. I would go insane if I went to a road course and wasn't allowed to get on the track and let 'er rip... and if I can't do that, then basically it looks like it's just going to be some FD wine and cheese tasting thing, and that is not my style. The dirt is buried deep under my fingernails and there's no way I'll ever come clean

NOTA V6

I beg your pardon, but I helped put this thing together, and I am doing my own engine swap. FD wine & cheese tasting indeed. Hmmph!

jeremy

iTrader: (1)

peejay, whats sport compact nats?

nota v6, i see your point. so it wasn't fully in vain. looks like a lot of fun. i wish i could come. i agree with pj on the rather be racing then watching thing. although both is best. guess i'll just enjoy your new pics.

NOTA V6

There is an opportunity to get reduced fee entrance onto the track for 45 minutes to an hour to do some lapping, coutesy of Mazda. You just have to read the whole deal before writing it off.