Fuzebox

Hi,

I am considering buying an '83-84, and from what I've read they have about 100hp and 100ft/lbs of torque, with 0-60 in the high 7's and run a 1/4 in 16s. This all sound accurate?

I was hoping some of you could break down what are the most popular bang-for-buck mods, what I would have to spend, and what sort of gains I can expect.

I've read a bit about porting, but am not really sure what you get out of it, or how much it costs. I'm also not sure if this year comes with the 12A or the 13B.

I'd appreciate it if you guys could help me out... Thanks!

rx7gslse

alright. the basics:

All models with the exception of the GSL-SE (made only 84,85) came with the 12a engine rated right about 100hp &ft-lbs.

There is a difference between the models s,gs, gsl etc.. Do a search and you'll find good explainations...

The quickest power mods is the breating path. Open up the exhaust, rig up some sort of a cold air intake, and you've increased your power a ton. (guess 30+) I've heard the next good gain in power would come from a carb upgrade.

Porting is the way to make max power, but this can only be done by taking the engine apart. So unless it already needs a rebuild, you might as well hold off on that.

That's a good starting point...

Fuzebox

I've heard of people getting 180hp+ out of a 12A from porting... Is this normal?

How much does a port job like this generally cost? Can it be done by a few amateur mechanics?

Thanks for the reply... I sort of figured on the intake/headers/exhaust part, but isn't 30hp a bit optimistic?

Thanks.

PaulFitzwarryne

In a nut shell

1. Upgrade the exhaust side, a good header and exhaust system. An example would be a Racing Beat system or a cheaper copy by your local muffler shop. Costs around the $700-1000 level fitted.
The outcome will be about +20hp.

2. Upgrade the inlet side, a modified Nikki same as a Yaw Power or copy. Costs would be around the $300 level. Change to a better air intake filter such as a K&N for around $40. At the same time duct cold air from the side of the radiator to the inlet using rubber hose. The outcome will be another 20-35 hp.

At this stage your car will perform like a stock 1984 gsl-se.

3. Your engine will be due soon for a rebuild. When the time comes have the ports improved to what is commonly called a street port. It increases the inlet and exhaust times like a mild cam on a piston motor.
It will cost you some $300 above the cost of a stock rebuild. Upgrade the fuel pump and add a regulator. Carter and Holley are good brands.
The outcome will be another 25+ hp.

At that stage your car will perform like a stock 1986 Gen 2 car and with luck if everything matches to an early 1988 turbo mpdel.

4. After that its a question of budget but the usual sequence I suggest is add a performance carb such as a Holley then improve the ignition side , go to direct fire like MDA.

Go to the Vendors sites given on this Forum as they contain useful information and costs.

What is often neglected is improving suspension, clutch and brakes. Quite often they give a better handling car which is quicker to drive.
have preference for Koni but others use other brands

I suggest buying the RX7 performance handbook from www.speednation.com. It gives good ideas but perhaps even more important set of lessons to learn before you spend money. For example you will never get the cost of improvements back when you sell the car- its better to buy a car which has been upgraded at someone elses expense!

PaulFitzwarryne

Regarding your second message.

Porting can only be done when the engine is stripped down for example at a rebuild

You can get templates for the shape to open up the ports. A good amateur like some people on this Forum can do it but its not easy and you can end up with a mess. For about $300 leave it to the experts.

You can get 180hp out of a streetported motor but the cost of porting is a minor cost in getting there. It is acheived when you have significantly improved the exhaust system, carb. air filter and fuel pump. With say a $2000 budget it would account for 15% of your expenditure on the engine side of improving the car.

Read the existing thread on porting for various comments at length

Fuzebox

All that work to get the performance of a 2nd gen?

Doesn't really seem worth it :/

I know all about suspension... Right now I drive an autox-built Miata that handles like a go-kart

What sort of 0-60 and 1/4 times could I expect with those mods (including the street port).

Thanks! I'm still not sure if I want to consider an rx7, if only because after all the work invested, it still won't be that quick :/

FuLLsMoKe

Trust me... You'll like it if you get one

Fuzebox

I probably would. My only concern is power. Right now my Miata is 0-60 in around 8 seconds, 1/4 of a high 15... I'd hopefully like to upgrade (I'm losing a convertible and great handling, so I should get something, right?) while at the same time saving money.

Also, I am getting the feeling that some 1st gen's have backseats, and others don't. Can anyone shed some light on this for me?

Thanks.

FuLLsMoKe

Last time I checked, my first gen doesn't have a back seat

Those back seats are custom

theNeanderthol

iTrader: (1)

If you want to go all out you can go for the bridgeport. It needs free flowing exhaust and a very good carb to give it what it wants though. If set up correctly, that set up could give you 275+ hp. With my exhaust, I went with a racing beat header, and run the stock exhaust back, except when racing. On the track I use 2 1/4 pipe from the header back. Lots of power, lots of noise. With a few weight reductions, you can get a pretty quick car without a lot of horsepower. PeeJay ran a 15.1 quarter mile on 130hp. I've heard he is a very good drag racer though. Get that rx-7 man ! you won't regret it!

hanman

You can find used back seats for the RX's made after 1980. They were an aftermarket item. They fit in the storage bins in the back, no storage bins = no back seat. Mazda started putting the storage bins on the 81.
By the way, my opinion on the first gen:
Racing Beat Header and presilencer
free flow muffler
Yaw Carb and ported manifold
MSD ignition
You won't like you Miata anymore.
just my opinion,
hanman

APT CSVT

The first gens are not quicker than your Miata. My 84 12A with a cracked case ran 17.3, but I doubt I would have gotten more than 0.5second less in better shape. Most GSL-SE's I've heard about with modest bolt on's are lucky to get mid 15's. So, if you want power, think crazy motor work or turbo.

BTW, you may lose the convertible, but I can assure you that you will not lose handling.

RXcetera

Paul Fitzwarryne, although many of your posts are accurate, in my opinion, your power estimates posted here are wwaaaaaayyyyy off. Maybe on paper these would seem about right, but in the real world, things are very different.

The first mod should always be a good exhaust system. If you go for a RacingBeat type setup, you should gain about 20hp as Paul stated. AT THIS POINT you should be even, or even beating STOCK GSL-SE's AND any NA 2nd GEN!! Add a Yaw carb to this equation will net you ~10-15hp, not 20-35! With full exhaust and a Yaw carb, you'll be eating up STOCK SE's, and most mildly modified Miatas. Your also going to be giving some TII's a run for their money (til 60mph that is).

The only way to go after adding these parts is porting. I wouldnt change from a Yaw to a Holley or whatever just for a streetport. A properly rejetted Yaw carb and good porting should net you over 30-40hp!

If you've been keeping track, your car at this point should be pushing ~180hp. In a little 12A first gen, with the stock gearing, you'll be BLASTING to 60mph. Not many NA Miata's will be able to keep up.

To APT CSVT, I suggest you look into this a bit more... My stockport 12A with "modest bolt ons" does low 15's (and I havent done anything to lighten it). Lightened 12A 1st gens can do the quarter in the low 15's with mods only to the exhaust. If you could only get 16.8's in a healthy first gen, you need to go back to the track and practice some more...

APT CSVT

I have not taken a healthy RX-7 to a track yet and I'm sure that 12A I took was not gong any quicker down the track unless it were being towed by a Lightning. That car was free to me, bought by a friend at an auction. many problems with it.

My 85 SE has 150k miles on it, stock. I keep the NGK's changed often ~6k miles) . I have a feeling the secondary port is not working, though. Anyway, I have two 15.0 second cars now and they are noticably quicker than my SE. I've ridden in a mildly ported GSL 12A (lots of options so not light) and the RB full exhaust and I'd call it close to my SE in performance. We didn't race, although we should.

My point is that most first gens with modest mods are going to be mid 15's. That's heavily dependant on the $700 racing beat exhaust which not everybody can get if they have to pass emissions tests. That puts him near the acceleration of the topic starter's prior car. To do significantly quicker than his Miata will take some more money. Not everyone is into spending $2000+ on a car the is only worth $1000.

Aaron

RXcetera

There are always ways around spending too much money though... used parts can be found relatively easily if one is willing to look for them.

I totally agree that mildly modified (ie:exhaust mods) 12A's tend to hover near the mid 15's, but not all 1st gens have 12As. If a 13B SE does mid 15's stock, then a nice exhaust and intake should (and does) drop it into the low 15's to high 14's.

I got worked up about Pauls post because I got out of it that 1st gens where expensive and slow (compared to Miatas and 2ns gens). Most people on this forum with nice 1st gens no this is definitely not true .

Fuzebox

So without porting, there's no easy way to get a 1st gen into the 14s?

stinkfist

If you have a choice, keep your miata. It handles a lot better and dollar for dollar can be made faster.
If you need to get rid of car, then by all means get a 1st gen. They are great cars to play with. It's hard to get them to go fast unless you go turbo. If your willing to do all the work and your resourcefull you can put a stock turbo set up from a T2 in for around $2,000-$2500. That will get you around 200hp after you have that custom exhaust built. It will get you a whole lot more torqe wich is what will make the biggest difference.
My car has a big street port 12a, light weight flywheel, Racing beat Road race exhaust. Racing Beat holley intake. Custom cold air induction, MSD direct fire, A good bit of wheight striped (~150LBS). I also have RB springs, Tokkico shocks, Suspension tech bushings, removed rear sway bar and a set of yokohama AVS I's.
With all of this done my car handles very nice and is quick. I wouldn't say fast. My G-tech says I ran the 1/4 in the low 15's And pulled .89 G's.
I should probably be in the high 14's but thats still not fast enough for me. My stock T2 feels way faster but I do prefer the modified handling of my first gen over the worn out suspension on the T2

I have driven miats both Highly moded and Stock. A stock miata with nothing but better rubber is much quicker than my car in the corners.

If I had to do it over again I would do a T2 swap from the start. I have around $5k in my car and I could have done a T2 for half of that. I love my car though. It's a blast to drive.

If you want to save yourself a lot of trouble you can just give me $2k for mine.

RXcetera

I cant beleive you arent even in the 14's with a full exhaust, a "big" streetport and a holley. Something is definitlely wrong there...

Fuzebox

The point is, I'm trying to sell my Miata, save the money, and buy a cheap car. There's people locally selling 1st gen's for $1k CDN, which would leave me a lot of money to pay my bills and stuff... I want to get away from dumping all that money back into modifying a car (but I want a decently quick car too .

I guess I'm trying to have my cake and eat it too...

I agree with RXcetera, it seems that with those mods and the weight stripping you should be doing a bit better in the 1/4... But I've never actually driven one, so I can't really say.

Maybe the 1st gen isn't for me. Sorta sad, because I like the look, and the idea of a good handling, super cheap sports car is what I'm looking for right now. $2k+ turbo setups aren't what I'm shooting for ATM.

I guess I sound pretty naive, looking to run 14s on under $2k in engine mods?

mar3

iTrader: (8)

Have the engine built to be strong at all the seals, apex and otherwise, get it balanced by Pro's and give the beast a 150 HP shot in gut from NOS. That will get you in the low 14s if not in the high 13's. Never put tires that will be able to grip like velcro at the line, though, or you'll grenade the rear-end or tranny...

RXcetera

Well... it IS possible with a limited budget. You'd need to find some used headers (100$,), straight pipe the rest of the exhaust, use a cheap muffler, find a used Weber or Dellorto (100-150$) and bridge port the engine. The total of all this would be around 2000-2500$. This, of course is assuming that you are intalling the parts yourself. With a Weber, bridgeport and headers you're looking at 200+ hp. That should get you close to the 13's. Not bad for 3500$ including the car .

PaulFitzwarryne

FUZEBOX you are quite right, without streetporting you cannot regularily get high 14s in a Gen 1. You loose a minor level of streetability and add a major jump in fuel consimption. As Stinkfist shows even with a big streetport this may not be possible for your average tuner.

Some tuners are above average like RXcetra and can do better, but good rotary experts are becoming harder to find. This is why so many RX7s are in the junkyard.

RXcetra, I fully agree with you that the Gen 1 is a better sports car than the Gen 2. From 1986 Mazda loaded up the RX7 with weight, and performance suffered. Thus, a gen 1 12a with equal power will walk away from a Gen 2. It was not until 200hp Turbos were an option that Gen 1s were outclassed. Gen 3s went further upmarket to make room for the Miata.

I am sorry you think my hp figures are out. The dyno figurs I have show a 12a engine with stock porting, well modified legal and streetworhy can be tuned to 145hp at the flywheel by your typical rotaey mechanic.

We are in agreement that with a street port around 180 hp is practical.

When it comes to 1/4 times I suggest with the same driver a stock 12a]100hp] woud be 16.8-17.1, a gsl.se[136hp] 15.6-15.9, and a T II[200hp] 14.7-14.9. However, your experience shows you can do low 14s with a 130hp Gen 1 which has been lightened.

I am not going into the argument over which of the two Mazdas are best, that is covered in another sticky and is really a personal choice.
However in general a Miata performs like an RX7 ten years older, its a simple Mazda marketing strategy to meet two different demands.

RXcetera

I agree with the majority of your post. It's when comparing the results of modified cars that I feel your #'s are a bit off. BTW, I said low 15's, not low 14's for a light 130hp 1st gen... god low 14's would be GREAT!!

PaulFitzwarryne

RXcetra sorry I knocked off a second from your time but I tried to remember it at 5 in the morning from a previous Thread!

I agree some of the my modified engine predictioned times seem a bit high. It could be highly modified cars are driven by more experienced drag strip drivers who can get just that bit extra by fast reaction and better gear changing. My times are down as the box seems very slow. Another point is the car may be optimised for 1/4 mile acceleration. I tune for better 50-70 acceleration times because in normal driving thats where I want my performance.

While times I use are relatively accurate, the hp figure is often suspect. For example is your figure at the flywheel or rear wheels? Most stock data is flywheel as given by the manufacturer, gurus like Paul Yaw use flywheel as they are testing on a bed, most home modifiers can only give a rear wheel reading.

stinkfist

Yeah something is wrong. It's the holley. I'm haveing trouble getting it to work right. But it still gives me a noticable difference in power over my modded Nikki I had in there before.