They have some information up on their website now.

http://www.groundzeromotorsports.com/



GroundZero 93-Mazda RX7 Lower Intake Manifold
Introductory Price: $495.00 dollars.

* Larger equal length runners.
* Can be used with stock or aftermarket
2 injector rails or order with the 4
injector system (extra).
*Comes in natural finish, upper half moves
forward aprox 1/2" (13mm), may require
the modification or removal of stock
brackets, not for highway use.
*Reduce lean conditions to rear rotor.
*Outflows ported/extrude hone stock manifold.
*Can be port matched to individual engines.
* Will aid in air/fuel tuning.
*Extra stock for porting, Cosmo included.

 

That's a really good idea to place the injectors like that. You can get top feed injectors for primary and secondary and it simplifies the fuel system so much. I think it will be best for people with single turbos and like 1000cc primaries and 1600cc secondaries with an aftermarket FPR and -AN fuel lines/fittings.

Too bad they haven't said anything about the use of this LIM for people who have the stock twins still.

 

If you have an ECU that can control 6 injectors, sure. But I think 850/1600 is more than enough for 99% of the people on this board, and you could always go with 4X1600's if you had to. I wonder how it compares to the RE manifold, it doesn't seem if the secondary ports are all that much larger than stock, of course it's hard to judge from that picture.

 

I'm still trying to determine if this is a reliability mod, a performance mod, or a combination of both. It seems by this statement:

...seems to indicate that it is a reliability mod. The next statement:

...seems to indicate that is a performance mod. I guess how much more is the question.

Does this mean that the buyer would do further porting upon receipt?

The questions I would like to see answered are:

1. Is there documented proof that this lean condition exists?

2. Is there documented proof that this lean condition actually cause any significant problem?

3. How much more does this LIM flow than stock?

4. How much more does it flow than a ported/extrude honed manifold?

5. How much more does it flow than the 13B-RE manifolds? (slightly larger if I remember)

6. What horsepower gains have been experienced (if any) simply by bolting this LIM onto a stockish FD? (similar question could be repeated for a highly modified twins car @ say 14 psi and for a highly modified single car @ say 20 psi)

I guess that's all for now. If you feel you KNOW the answer to any of these questions, please answer them providing applicable proof, if available.

Thanks

 

I was talking about removing the whole primary fuel rail and injectors, and blocking the injector bungs off, then just using the two injectors on the two primary runners as the only primaries, for a total of four injectors.

 

I don't think this will work with the twins. Even if all the lines and pipes and whatnot cleared the manifold, there are no vacuum ports going through the LIM, so you would have to route at least three lines around the manifold (CRV,CCA, nipple on back of y-pipe).

I also don't think it would be wise to use the primary injectors in the LIM only. As in, not using injectors in the stock primary injector location. It seems that the injectors are in hte intermediate housing to help the fuel stay atomized, and go right into the chamber. If the primaries were all the way in the LIM, it may affect driveablity at low load/low rpm cruising.

The other thing I was curious about, is will they supply a matching LIM to engine hasket with this? If you hold your LIM gasket up against your LIM, you'll see that there isn't much room to grow. If the ports on this manifold are that much bigger, and you use the stock gasket, it may actually poke into the airstream which would probably hurt flow.


Oh, and one more question. If the reason FDs blow the rear rotor's apex seals more often because of the LIM, then why do the TIIs. It seems that any turbo rotary is more likely to pop the seals on the rear rotor. If it the LIM on the FDs causing the problem, then is there the same problem with the TII manifolds?

 

kind of dumb post because mines stock and stored----but i spanked a ram air car(firebird or camaro?)big twin hood scoop we both took off well----to 70 mph hell yes ya can run lean and if i do i blame you

 

rich=safe

 

glass man i want to run ya im stock bitch

 

dodnt worry ill win

 

Size doesn't matter when flow is concerned!

 

They supply a special gasket.

 

Just look at the stock manifold! You can clearly see why there would be a flow differance between the front secondaries and the rear. The rear secondary port has a strait shot into the engine while the front secondary is curved. That curve will slow down the velocity of the air. Rob Golden said at sevenstock that the stock manifold was poorly designed and flows unequally.

Tomorrow I will take a side pic of my 20b LIM. It has simmilar issues.

 

Tell that to the Cosmo intake!

 

 

so instead of having 2 injectors above and 2 below they are now all in a row? with only 1 fuel rail? am i correct? and they offer another 4 injector upgrade for a total of 8 for really crazy hp outputs? am i right in saying this?

but are these intake the size of the cosmos? or bigger, or smaller?

the design does look much better

 

Just to give you a guys a heads up..... Ralph the tuner, is no longer with Groundzero. He and the dyno are re-opening under his old business name of Xcessive motorsports. I don't know much about the guys at GZ....but I do know that Ralph is the guy is did the rotary stuff there. From what I gather, he will still be doing the oil pans and manifolds. CJ

 

I know very little if anything about intake manifold tuning and design.

But looking at the stock LIM, I observe that the front primary and secondary runners appear to be the same length and the rear primary and secondary runners are the same length as well. The front runners are longer than the rears.

Is it possible that the Mazda engineers designed the runners such that they increase volumetric efficiency and not because they were constrained by spatial limitations? Do different runner lengths minimize pressure waves in the manifold due to difference in timing thus increasing flow?

Perhaps equal length runners are not a good thing????

Anybody know about manifold runner design and volumetric efficiency in a turbocharged rotary engine?

 

Don't do it! I bought my fd from a car dealership that works with Groundzero Motorsports, my car was stolen before they got it, but almost everything they said they fixed ended up being just as broken as before. They put the wrong fuses on things so most of the switches and stuff shorted out, lots of the bolts were stripped, and as far as the body goes, they just stuck on the things you could see and left the rest broken. I'm not the only one that I know who's had a bad experience with them, one of my friends took his Celica to get a hi-flow exhaust installed and says that it ran worse than when it was stock. So he jacked the car up to take a look, and said that all sorts of things were broken off the bottom of the car. Maybe if you did all the labor, thing would turn out fine, but I'm not going to trust them to touch my car anymore. Just thought I should let you know.

 

They probably only fixed what they were paid to fix. Dealerships tend to pay for the bare minimum work that will get the car sold. I dont think I'd base your decisions off of that. As a matter of fact unless you talked to someone at Groundzero about the situation how do you even know that the dealership really had the car worked on there...or that ALL the work was dont there. They might have just be trying to get out of making it right by placing the blame on someone else.

Also...what would they have broken on the bottom of your buddies car just by changing a cat back??? Especially something that would have made the car run poor.

Who knows though....maybe this is why Ralph decided to leave and start his own tuning shop back up.

Stephen

 

Ok here's the pic of my 20b LIM. You can clearly see a differance with the center secondary runner to the center rotor as compared to the secondary runners that lead to the front & rear rotors. The forth runner from the left is the secondary runner for the center. Look how it has a strait shoot into the engine while the outer runners are curved. From what I understand when you blow a 20b engine, the center rotor is usually the one that blows. Hmmmmmm I wonder why?

 

wow why is one of the intermediate housings so much bigger than the other?

 

I would guess because it has to hold a extra stationary gear for the middle rotor.
I've always wanted to see how it was mounted.

 

And because there is a secondary port in there. You need more room for the runners of a seconary+primary than you do for two primaries.

 

good point