Hey all,

I'm looking at sticking a N/A rotary into an Opel GT project car I'm working on and I'm wondering what kind of performance I can get out of it with what I'm planning on doing...

So I'm looking at putting in an 89-91 engine and running a Haltech E6K. Custom intake, will prolly be some sort of a ram air setup. custom exhaust fitted to what will work on the car, planning on going with about a 2.5" exhaust with no cat or a high flow one. Also planning on stripping the air pump, power stearing, A/C and all that junk, and putting an electric water pump on it. Hoping I can get 200-250 HP out of it without much trouble


Another question I have is how much an assembled engine weighs? trying to figure out a little bit of the power to weight ratio. Stock the Opel weighs just a tad over a ton, and the engine that is stock in it is pretty heavy for a 4 banger so I'm looking at about 1k lbs less than a stock RX so it'll move along nicely =)


Thanks for the help

 

There was a thread out here as to what all you need to do to a NA to get the most out of it. But I cant find it right now. Maybe someone knows where it is or bookmarked it.

 

- get a mild streetport (for more info on porting, check out Mazdatrix's faq )
- lightweight flywheel (never-ending debates on whether lightened steel is best or if aluminum is steet-able.)
- electric fan
- intake and exhaust are the main key to power on an NA motor.
- forced induction: check out Atkins Rotary for their supercharger. If you're going with your own fuel injection setup, you could use theirs that will bolt up to it.

One thing to think through: if you remove the air pump you need to figure a way to open the 6 ports. Rotary Performance was supposedly looking into an electronic actuator, I don't know whatever came of it. And if you do use a supercharger, you could use manifold pressure to trigger them.

 

thanks much for the links and info, I'll have to check them out

Thanks for the heads up about the long performance link, I found one that was like 5 pages long that went through a lot of stuff and gave me a few ideas.

 

I would think that with with an after market ecu/maybe a differnt intake manifold alltogether, on a stock port engine, i bet you could make 220-225flywheel hp. From what Rob at Pineapple and i have talked about, the stock intake system on a 89+ is limited by the amount of air it can flow to about 190-200hp The lower manifold is realy bad.

I'm just guessing on the 220 numbers, but if you e-mail Rob he could set you up with some realistic numbers. Not just numbers that i THINK you could make.

That differnt intake manifold thing, gives me an idea. CJ

 

I've always wondered about the intake manifold on the 13B, so many turns and bends in it. Take a look at the picture from Atkins site below, its a 12A with their supercharger setup.

The carb sits on top, air and fuel go through the blower, it makes 1 turn and straight into the motor, far less complicated. So imagine this: a throttle body sitting right where their sc is. That would certainly clean up the engine bay.

 

Making a new intake manifold prolly wouldn't be too much trouble... in fact I might end up having to do it in order to make it all fit under the hood of the opel... would kill 2 birsd with one stone... free flowing intake and clear the hood

 

The best setup for something like that would be a ida style intake manifold, with some 50mm throttle bodys. They flow pretty good. CJ

 

I'm going to be making my own tunnel ram type manifold out of constant-radius exhaust tubing, and welding together the plenum from sheet stock.

Goal is to run an Edelbrock 500cfm on my car... wish to support 225 or so HP at the flywheel. Trick will be putting some texture/roughness into the tubing to keep the fuel from wetting out. Of course I could always just go port F/I but that costs a LOT more money, and has a "flatter" feel to the power delivery that I don't particularly like.

 

I shure you're aware of the constant debate of holleys/elderbrock vs. webber. I'm a fan of the webber. CJ

 

In that supercharged picture, is that 73 and older rotor housings i see?? Notice the exuast sleeve style? I'm pretty shure it is....but the water pump looks aluminum. I beleive that the aluminum water pumps did'nt come out until 86, and thats what it looks to be. That is, ulness you had lots of $$ and bought an aluminum one through mazda comp. Where'nt they around $600 new? Then the altinator is off of a 81-85, i think. Someone correct me if i'm wrong.

Just looks like an odd assembly in that picture.

 

Yes, and I think Webers are killer, too... (mmm... 51IDF... *drool*) but it's kinda difficult to have a half-bridge with primary and secondary separated with a non progressive 2-barrel. I've been considering ways to do it, but it gets far too complex and I much prefer simplicity.

Although of late I've been thinking of just making the street port bigger and running a 48IDF and be done with it. I'm worried about how well the Edelbrock holds up to g-forces, especially mounted sideways. Weber I know would have no problem.

I know that Q-jets will run any which way but completely upside-down with no complaint, but parts availability (Where to find jets/metering rods/etc.?) seems like a total nightmare. They *are* plentiful, though....

 

I have used the edelbrock afb style carbs alot, in stock form they do not take well to off-camber situations and g forces, in my 4x4 they would always flood or cough when flying through mud holes or steep hills, they sell an 'off-road' needle and seat kit that totally fixes the problem though.
You may want to consider running the 625cfm carb, I find the edelbrocks to be a little overrated when it comes to cfm..The tuning kits for the carbs is their strong point, you can manipulate the a/f ratio alot easier than with a holley, and the parts can be changed in a matter of minutes..
Fuel pressure is vitally important on these carbs, because the fuel bowls are relatively small for the cfm of carb..Max

 

Hmm, interesting.

I did note on the Edelbrock site that the 500cfm and 600cfm carbs have the exact same throttle bore diameters and venturi diameters.

A member of Mazspeed.com is running a 650 on a half bridge and he says it works reeeaally well. I like that it has differential-bore sizing, secondaries bigger than the primaries.

Unfortunately my goodies budget has just been drastically reduced by recent events... the refreshening looks like it will turn into a full out rebuild if there's anything salvageable.

 

has anyone tryed to put forced oxygen into the airbox from a bottle

 

Don't forget what happened to "Challenger"..

 

interesting idea 88'gxln/a, I'd thought of that a while back, after all N20 kicks butt because it has something like 30 or 50% more oxygen than "air".... you'd have to get the fueling right of course! In WW2 they used to use N20 on high altitude fighters.... why didn't they use oxygen? It burns nicely (a'la Challenger - SureShot! )

 

O2 you guys are silly and crazy. If we could only get together and cause mayhem.

 

Pure O2 will cause rapid meltdown of the engine... nitrous oxide works OK because the separated nitrogen acts as a buffer to slow down the combustion.

Go ahead and try it... just remember to bring a spatula so you can scrape the remains of your engine off of the ground

 

The bottom tension bolts go thru the rotor housings on the old engines I believe. I know on my 73 12A they do.

 

anyone have more info?