whats the difference? iam wanting a manifold for my 12a sp engine.

 

IDA will kick them sidedrafts.

 

The side draft will wrap around your engine, with the carb mounted on its side. Generally speaking, the down draft will not fit under the hood.
If you run a search you will find tons of info on both.

 

so it changes the tq curve?

 

Stock carb, side draft and down draft will each have difference torque curves. Anytime you change the plenum size and length you will change the torque curve.

My experience with a stock four barrel, was that it was quite progressive and gave me a bit more bottom end. Since rotaries are not known for bottom end, I looked to get more power farther up the RPM range. This is why I went with a side draft. It give me great power through the mid-range and let the engine really rev. I think this works pretty well on the street.

The down draft IDA Weber is probably the most notable induction setup for a rotary engine. This setup is down right legendary and is great for bridge port engines. This carb setup will sit about 6 inches above your hood. An awesome setup for all out racing.

So, what are you building the car to do? Race it or drive on the street?

 

the 12a engine is a big street port. one of my 1st rebuilds, its going into a fully gutted 83 gsl. i want it to be steetable/race more towards race. after a bit i want to do a half to full bridge port.

 

Ok, if that is the case and your do not mind a big old air cleaner sticking out of your hood, the IDA would be the way to go.

Try searching with something like "jetting an IDA", this should give you an idea of the choke size and jets you will need for a down draft.

If you want to get wild (and you have the cash) there is a great fuel injection setup with a 50 mm throttle body and a stand alone injection system. This way you can control everything without having to buy a new jet or needle everytime you want to adjust somthing.

Good luck!

 

cant i have a IDA side draft? whats ida,dcoe?

 

Nope, and IDA is a down draft, turn it sideways and the gas will pour out.
(the floats are designed to operate in one plane).

Here is a GREAT link that discusses this whole topic - http://www.vintagerotaries.org/index.php?showtopic=17

 

IDAs don't have to stick above the hood. Some do, but it just depends on your intake manifold design. IDAs make better top-end than DCOEs, but the low-end suffers somewhat. Nice thing about sidedrafts is that they are much less affected by lateral g-forces. That's why I'm using a sidedraft for my turbo project.

 

In order to use the full advantage of the IDA, you need the longer plenum runner length. This results in the carb through the hood. Yes, there are some IDA shorty intake manifolds and they work well for turbo applications (the folks at Tweekit love them.) For an NA application they do not have the plenum length to use the IDA to it fullest.

 

^ That's probably true, though they still can be used with good results with the short-style manifolds.

 

If you use the spacers (phoenolic sp??), the IDA's air cleaner will rub against the hood. I dont use it in my FB and no noticeable change in hp.

 

Wrong. Sidedraft will yield more bottom end vs downdraft yields more top end

 

Got the IDA with with Phenolics on there and the hood closes fine Mel!....sheesh, some dumb *** posts on here about this six inch about the hood nonsense! Maybe with the 7" velocity stacks!

 

BTW>>>They make the best power, but there is a learning curve. Fuel consumption can be equaled to a modded Nikki with a much larger rush at the top. They CAN be made to idle smoothly and run well when cold....really cold climates will need a little more warm up time, but they are definatley fun.

 

^ Hows come you are still using the beehive?

 

coz he is a noob

 

...actually its an old pic....the beehive has since been replaced by a 2nd Gen oil cooler Now if I can just get a tranny to stop effin' up on me! (BTW...the factory RB rear oil cooler line fits fine, the front needs to be remade a little longer.)

 

By the way, I've never gotten any feedback from that, and I'm curious what folks think. If there's something you feel should be included or revised, please let me know.

 

coz it was plagiarized (sp??)

 

Nope. I've got his permission to reprint, and am revising it with up-to-date info. The original author is also credited in the header, and has been since day one. You'll find similar credits in the transmission and diff writeups, too.

Now that Paul Yaw is out of the game and the world always gets new dead links, I'm going through everything again.