can someone give me some info on these? I've heard them mentioned, but not sure they do exactly. I take it they're for turbo cars running carbs.
Where can I find some?
Is anybody using them?
If so what kind of perf and reliability?

 

Its a regular carburator, with an airtight "hat" or "bonnet" so the pressurized air can go through them.

Hence, the name a "blow through" Turbo system.

As far as I know, there aren't any made just for blow through operation, although some are better to use than others. There are aftermarket companies that make these bonnets, or you can custom fabricate one.

For your TII engine transplant, a Blow-through Holley turbo system works quite well, relatively inexpensive, an reliable.

A guy not to far from here has a Streetported Turbo Holly 13B putting down about 320 horses at 18 lbs of boost It can do much more if he wanted to, but then reliability would be compromised.

 

Blowthrough or drawthrough just mean where the carb is in relation to the turbo. Blowthrough means the turbo blows through the carb, drawthrough means the turbo draws air through the carb.

 

How do I set it up?
I had a GXL with a weber side-draft put on it, pretty much the same?
I'd appreciate any input
btw...320?!?!?!?! DAMN!!!!! I need me some of that

 

Your weber side draft is one of the ideal carbs for a blow through set up. In fact if has a brass float all you have to do is re-jet it!!!!

Ryan

 

If you check out mazdaracing.com they fabricate these "bonnets" for the 12a. As well as turbo kits, and other things.

 

Although Mazdaracing makes alot of the blow through stuff, they are not recomended. I have heard enough negative feedback that I will not do buisness with them. On the down side, this has forced me to do extensive research on blow through carbs, and now I have to risk a motor trying to set one up for the experience factor. From what Mazdaracing advertises, they are awsome blow through guys, but I have never met any one that has a blow through from them, I have never read any articals or even heard second hand information on their setups.

What I am doing is starting with the side draft kit from Mazdatrix, bumping up the main fuel and crossing my fingers. Mazdatrix's kit BTW comes jetted and set up for install on particular app. It is not setup like a Yaw Power (your specific altitude, type of racing, exhaust, ect,ect) it is the general rotory set up. To get the most power from the carbs you must do the fine tuning, which what you have to do with a blow through carb anyways.

Ryan

 

From what I've heard, Mazdaracing just puts bigger jets in there (too big?) and ships 'em out.

 

Damned.

I guess they can't be all too legit if they have streetracing going on. I'd sure like to have that engine from that blue car though! Would make a great sleeper.

 

So in short.....easy to set up???

 

No, not easy to set up. You'll have to do some serious searching and learn as much as you can.
If you approach, or even think of this as a "bolt-on" project, you'll be some damn sorry!
Doing this from scratch is walking a tight rope...You're on the knifes edge of grenading your engine. There are very few fail-safes to insure that you do not.
Now if you can really let that sink in for a second, and know that these are not the projects of nieve beginners just "playin around", then you can get down to business.
That's about where I am on my project...I have learned "just enough" to start planning it all out. The best thing (totally in my opinion...but I'll bet others', too) is to completely research the whole thing, and plan it all out perfectly. Then go over every detail by asking annoying questions. Then start gathering the bits and pieces you need.
I am planning on doing what I call a "Junkyard Blower Setup"; in that I'm installing an old (rebuilt) Eaton M-62 blower from a pontiac on my stockport 12A. It'll be in a blow-thru configuration, and I'll use things like a stock Starion or Volvo IC; and make my own water injection system, ect. All of the ductwork, carb box, and blower plenum I'm doing myself.

My plan is to have a reliable, "bullet-proof as stock", 10 psi, 225 HP stockport 12A.
I will be using a Nikki carb that I'm in the process of moding for this application.
I also have four 12A engines, so I have the luxery of relieved stress. Ithink it's important that if you do this, you start it on a crap engine, get it working, tune and tweak it all up pretty, and then swap it to the engine you really want it on.

 

I'm looking for the same thing..only 500hp and nitrous
I asked about a water injection system on a previous post.

 

Sterling,

How are you getting away with the Nikki. I've spoken with Paul Yaw and he woun't even atempt the project. What are you doing to make it work?

Ryan

 

Got a few hours?

I've taken a Nikki a step further than Paul for tunability over a wider range. It's specifically for this application, and the changes I'm making would'nt be any better than Pauls carb on an NA 12A. But I'm also taking alot of time grinding the carb down, remachining bits, making my own linkage set-up that is completely adjustable (for example, I can change the stroke and timing of my secondaries relative to my primaries with a turn of a nut), crap like that. It does'nt even resemble a Nikki carb anymore.
It's all very labor intensive. Just takes alot of time.

On my daily driver, I run a Yaw carb that I've done a few mods to myself in addition to Pauls.
I would bet good money that when things are just right, I'm getting over 150 HP at my peak RPM- without a cold air box.

Pauls modded Nikki flows about 415-425 cfm at 14.7 psi (atmospheric). But you can just throw that right out the window when you try to blow 24.7 psi (an additional 10 psi worth the boost) thru it. Now it flows lots more.
Think about it. Can a turbo blow 20 psi through a 3 inch diameter hose? Certainly the combined area of the carb is greater than that.

I've done the math in many previous threads, and decided (with help from others) that the Nikki will flow fine for me in this application.

The higher pressure flowing through will be effected differently by the venturi angle I think. People use Webers for blow thru application without changing the venturi profile. They may indeed go to a larger diameter, but I never hear of anyone machining a venturi to change its profile.
I plan to experiment with different venturi profiles to find one that is optimum for any given boost that's feasible.
(I won't be seeing how much boost I can go to without blowing the engine...I don't think!, anyway!)

I'm making my own manifold and it will be an integral part of the whole set-up. I'll have places for water injection and fuel injection for an electronic accelerator pump I'm working on. It wont look much like the stock manifold at all. This whole thing will be real funky...A bit of carb, a bit of fuel injection, who knows; Maybe even a bit of nitrous! (Totally kidding!)

As I start I will document the whole thing with photos, and post them all.

 

Maximum Boost by corky Bell at amazon.com.
Turbochargers by Hugh Maccines (I think)

Get them and read them. They will help you understand the principles of turbocharging, and you'll learn not only to ask questions, but what questions to ask.

 

Sterling, I've been considering the same type of setup. A junkyard Eaton and IC. Take pictures. I only have one motor so I have to be really careful. Thanks.

 

Guys, we used to supply blow through kits using weber IDA type carbs and have done several DCOE set ups. Do not think bolt ups will just bolt on and work, if you want any reliability you must pay special attention to boost refrencing your fuel pressures, float chambers and tuning. You must also use a 12at distributor or regraph what you have to give you no more than 15deg. total. You also cannot rely on the fuel bowl to act for a surge tank and have a very limited max power until extensive work is carried out on the fuel bowl. Be extremely careful as regular blow ups will occur, ASK ME HOW I KNOW! research this one carefully as mistakes can make this a pointless exercise. Please post if you are unsure.
Regards-Anthony

 

Anthony,
What did you do to prep the DCOE? I have been told by the guys at Peirce Manifolds (a self proclaimed Weber specialty shop), in Ney York that the DOCE is physicly turbo ready. I take that to mean bolt it up and go. Am I wrong with this ASSumtion.

Ryan

 

i know on the old school carteck kits they had a weber ida down draft. and a boost sensative fuel presure regulator... seen 1 up close and personal. just for example at idle you get 2.5 psi and when on the gas @ 5 psi (boost) it ups the fuel presure to 8 psi then @ 9 psi (boost) the fuel is uped to 12 psi. this helps the carb from A running out of fuel and B (i would think) the higher fuel psi will over do the seals in the carb and give more fuel than needed...a RICH a/f ratio. and on the ida i saw @ like 10-11 psi it was forcing fuel out of the carb seals. so i would think a stronger gasket in the carb would be needed.

 

BTW what is the cfm of a weber (48 or 40 )
nevermind ill post a thread