d k

Hi,

I am a total newby to rotary engines. I have lots of experience with piston engines and also 2stroke shifter kart engines, but not rotaries.

Looking to get info and questions answered like what is a Bridge Port mod? Also, what are the differences between a regular 13B and a BREW??

I am looking to build an FD that will see a lot of track time. It won't be a full on wheel to wheel race car, but it will be durable enough to withstand all day abuse at a track. What is a safe amount of boost without blowing the seals and doing other damage, what else are weak spots on these cars?

I read some posts here about single turbos and seems that there is no definite answer as to which setup is better (for track use, that is). I am looking to make about 400 to 450 at the engine. Will stock turbos with a boost controller handle it?

Also I read that in Japan, they had a better ABS system than us cars. Is this true?

Where can I find information to those questions? Any help is highly appreciated.
I have searched here, wiki and google.

Aaron Cake

iTrader: (1)

This page is a little out of date, but basically answers your question.
http://www.mazdarotary.net/porting.htm

A 13B-REW is a regular 13B. It is the code for the twin turbo 13B found in the FD RX-7.

Totally depends on the turbo and the rest of your setup. My personal advice is to choose a turbo which will make your power level at below 18 PSI. That keeps it in the realm of reliability without having to push much boost.

If you intend to track the car, the turbo won't be your primary concern. It will be the cooling system needing the most work. The FD cooling system is, how shall we say, inadequate and poorly designed.

You're not going to make that kind of power on the stock turbos without cranking them up past the destruction point.

400HP at the engine is fairly easy and one of the best turbos for a stock or street port 13B is the GT35R. There are plenty of kits available and the thing makes boost like the stock turbo.

Wouldn't know...

dgeesaman

iTrader: (7)

Bridgeport is a porting modification that opens the intake a whole bunch. It's not really streetable.

13B is the engine found in 2nd gen and later 1st gen RX-7s. The 13B-REW is a later version with twin turbos added on. The 13B-REW is the stock engine in the 3rd gen RX-7.

Yes you can make a trackable FD. Oil cooling and water cooling system mods are a must. Low-heat turbo setups like a single turbo help a lot. Auxiliary injection systems help immensely.

The ABS system on US-built FDs is a 8-bit system. It went to 16-bit in 99 I think. I know a few folks who have updated but it's not considered a critical mod. Many track guys prefer a big brake kit and no ABS. In any case the stock ABS systems are not that bad for tracking and they will help save your tires.

You will find a lot of info in the 3rd Gen FAQ. Howard Coleman has built a great car with your exact needs in mind.

d k

Thanks for the info. I will look into me Coleman to see what else I can find.
Out of curiosity, is a single turbo the preferred setup? Any drawbacks? What's the boost level that you want to be at for road racing type application?
Aside from cooling mods like oil coolers and radiators, what seems to be a weak point in an fd? Seals?

I will keep searching and thanks for the info

FbDrift

draw backs to a single turbo are typicly lag, depending on what size you run. boost level? that all depends on how you tune it, your hp goals and what supporting mods you build it with.

Aaron Cake

iTrader: (1)

It really depends on your HP goals. If you want 400 wheel HP with the response of the twins, then a GT35R is hard to beat. I recommend this turbo all the time because it is one of the best for a stock or street port 13B. 400 wheel HP is available around 18 PSI if you have an efficient setup. A little porting and it should come around 16 PSI. Pick the biggest T3 sized hotside, which I think is the 1.06.

The FD is the weak point of the FD.

Basically, replace all the plastic parts in the engine bay, get as much airflow as you can through the rad/intercooler/oil cooler and run a well tuned standalone. The enemy of the FD is heat and from the factory, they were a thermal disaster. Removing the stock twins and precat goes a long way to eliminating this heat but remember the radiator is almost horizontal. It's ducted, but in practice this doesn't work well.

d k

GT35R is what we've used in S2000's as well. An awesome turbo.


Thanks for the info so far.

Aaron Cake

iTrader: (1)

You'll find that the 35R on a proper rotary engine is a totally different beast.

d k

looking forward to it.....

When I drove my friends FD, I was totally blown away. It was like: how did this car go under my radar for so many years??
It was probably from driving Formula Mazda and being so apalled by the puke like sound.....
The FD, on the other hand, slightly muffled and with a bridge port mod, the idle was one of the best I've ever heard.

Aaron Cake

iTrader: (1)

One thing to mention is that if you are bridgeporting the engine, a GT35R is far too small. I'm not sure from your posts if you have decided to go that route or stick with a stock/street port.

d k

I have not decided anything yet. Just getting information.
I was going to build a 240sx, but after driving my friend's, I am pretty sure I will get an FD and mod it to suit my needs for a track car.
If a 35R is too small, I will have to get something bigger like a 40 or something.

I was just amazed at the handling aspect. Very similar to my S2000 race car that I had, but without the limitations of the F20 engine and the weak drivetrain.

D