I have been searching and have found some information on draw through turbo setups, but nothing very good. I am interested in turboing my SA and have decided on a draw through setup, but can't find any information on how to do it. Does anyone know of any good how-to's, walkthroughs, or FAQ's about draw through setups? Thanks

 

their a bit harder to fabricate because the carb doesnt connect to the intake ports of the engine, so you need something to hold the carb up, and some kind of tubing under the carb to go into the turbo. then from the turbo to the intake you need more tubing. the hardest part is having support to hold it all up i think.

on the cartech, they had brackets and holes so each individual piece connected to one another for support.

heres step one for a DIY drawthru, hehe
1)cut off part of the old intake manifold, weld pipe with a hole in the center, ends closed to it (open to the intake ports of course) use rubber hosing and clamps to connect it to the turbo. ends up with a kind of fork shape with the handle to turbo, forked end to engine

idk how u want to hold the carb up and connect it to the turbo

 

I suggest you pick up Corky Bell's book "Maximum Boost".

Posts such as the previous one, idk. I'm still trying to figure out what he said.

 

sorry, im not sure how to convey it.. ill try to get some pictures of mine up sometime

 

Draw through means that the carb is sitting infront of the turbo inlet. Blow through means the carb is on the intake manifold and the turbo is infront of it.

Draw through:

outside - Carb - Turbo - Intake manifold

Blow through:

outside - turbo - carb - intake manifold

If you're going to do a draw through setup, just be aware that you're going to be pumping oil, gasoline, and air through the turbo inlet. Draw through setups are typically used on superchargers since you can mount the carb right on the intake on the supercharger, but it should work with the turbo. You may have to do a front mount turbo, which means, more piping on the exhaust and intercooler, if you're going to use one.

For a turbo, I'd suggest a blow through setup. If you had a supercharger, I'd suggest trying to stick with the draw through.

http://www.dune-buggy.com/turbo/carbureted.htm

 

The easiest carburetor to use would be a side draft Weber 40-55 for the inlet of the turbocharger. Most of the VW High Performance shops sell the intake carb adapter to the inlet of the turbocharger. Then just use silicone hose to clamp the carb to the turbocharger inlet. You can use a regular fuel pump but, you just have to keep the bowl full of fuel. No need for high volume fuel pressure regulator "FPR" in these applications because the carb will never see boost because your pulling/drawing the air thru it. I say these are simple because out of all the big power adders available for the Rotary this is the simplest and cheapest way to make good cheap reliable power.

Use a Turbo II style lower half Intake with a 2" aluminum tube the length of the manifold cap the end closest to the Firewall and drill out holes for your intake runners then weld it on. The end that is open should be facing the front of the car next to the turbocharger. Make a tube to bring the turbocharger outlet to the open end of the 2" tube on your manifold. Use 2" silicone hose, clamps and your intake is done.

You can use all the stock Mazda Turbo II exhaust components even the flapper valve that controls boost.

Here in California about 15 years ago I used to sell alot of motors to a shop in Sun Valley and they would buy the stock Turbo II blocks and do what I listed above. On sandrails and they were actually reliable systems on stock unported Mazda Turbo II blocks. It was incredible to see a good cheap budget system put together for the local off road guys. To make boost come really quick they would squeeze a 100 shot of NOS to wake up turbo. They estimated these budget systems at 350 to 400 horsepower.

Cheap Fun

Good Luck
Albert

 

Try searching the Ausrotary forum. There used to be some very quick (9, 10sec) draw-through setups back in the day.

Like rotaryengineering said, it's very easy with a side-draught Weber. It needs to be very big though to flow enough air and you can't use an intercooler so it's good to run water/methanol injection for charge cooling.

 

Way more custom fabrication with a draw through and not really any benifits except no need to boost prep the carb...

 

How exactly do you boost prep a carb, then?

 

How is there any more fabrication then a blow-through? Wack on a DCOE Weber with a simple Y pipe and fabricate a plenum for the intake manifold. Not much else to it.

 

I strongly suggest you pick up said book.

 

So the case seems to be that the hardest part of the whole deal would be the intake manifold. Is that something I will need to fabricate, or are they sold for descent prices somewhere?

I think I am going to go try to find that book tonight. Thanks for everyone's help.

 

Another quick question. I just read that if you are using a draw through setup, you need a carbon seal turbo because a more common dynamic seal will leak oil into the engine when you let your foot off the accelerator (creates manifold vacuum inside the compressor housing). However, a lot of RX-7 guys premix oil in their gas anyway. Does that mean that a dynamic seal turbo would work in an RX-7?

The site I got this information from is pretty good. The URL is: http://www.smbaker.com/rail/monsterturbovw.html