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Want to build Drawthrough Tubbo with 40mm CV carb

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Offline one mile

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Want to build Drawthrough Tubbo with 40mm CV carb
« on: November 14, 2009, 07:20:33 PM »
Has anyone looked into doing this setup before?  I have worked with other unique setups before, and I  think it could work. Does anyone want to help me save time and money with some solid info? Stupid ? Not Stupid? Maybe? Maybe not? How about some input! Everyone here have been great so far! Lookin forward to your posts.
"WORK SMART NOT HARD"

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Offline cobleeze

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #1 on: November 15, 2009, 03:13:14 PM »
I'd be interested in this.

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Offline muskegtracker

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #2 on: November 16, 2009, 01:50:41 PM »
If by draw-through you mean the turbo is between the carb and the intake, I don't think it is a very good idea.  From what I've read the air/fuel mix going through the turbo will create problems with transfer of the mixture.  A draw-through system is best used with a dry plenum aka multi-port fuel injected setup.  I'll see if I can find the exact section in a book that I have.  Ah, here it is:

"The draw-through system is simpler and, because it is a low-pressure system, no change occurs in air density at the carburetor.  Further, no compressor bypass valve is required.  That is all that can be said for the draw-through system.

             RULE: The draw-through system is prone to icing at temperatures under 50F.

The blow-through system has better throttle response and cold starting, reduced emissions, and permits use of an intercooler.
Weighing the merits, there is virtually no reason to build a draw-through system unless one lives in a year-round hot climate and never intends to produce serious power."   Bell, Corky (1997). "Maximum Boost: Designing, Testing and Installing Turbocharger Systems". pp. 102. Bentley Publishers

Well, I guess that about says it.  I hope this comes across just as useful information.  I know here on the forums it is hard to get a tone of voice and feel where the person is coming from.  I'm just trying to give you some helpful info.  Good luck either way.  I'd love to see pics of whatever setup you decide.  With all that said, I did have a friend who ran 13 psi on a home build draw-through system on his carb'd Mazda truck for a short while - until the engine exploded.
« Last Edit: November 16, 2009, 01:52:18 PM by muskegtracker »
91 Chevy Tracker
2.7L V6, Coil-over Suspension, ARB, and other goodies...
My build - http://www.zukiworld.com/forum/index.php?topic=25353.0

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Offline one mile

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #3 on: November 16, 2009, 09:57:48 PM »
Love the Input! Man I tell you that you just can't argue with a man that has paperwork to back it up! I do agree with everthing you said, BUT I am only looking for a little "Boost" in power (Ha Ha) and I have done a few blow through systems but the $ in them was high. I ran a R-KAY Draw Through system on a "Full Tilt" Mazda rotary and it was great till I "Upped the Boost" and killed the Apex Seals. This was back in the Stone Age to most, (around 1985) that I started messing with Turbos. I was mainly looking for someone that has "Been There, Done That" so they can steer me in the right direction before I get started. You know stuff like compressor housings size Etc. , Etc. I am not planning on going into the motor for anything at all so boost will be around 5 lbs. with a boost retard and a good Ignition system. But maybe I will abandon these thoughts for just a Carb, Cam and Exhaust. I do belive though that I can keep good gas mpg,s with a stock motor with low to moderate boost on a small Turbo  just as long as I run good gas. Any body? Pics ? Criticism ?
"WORK SMART NOT HARD"

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Offline one mile

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #4 on: November 16, 2009, 10:10:28 PM »
OH Yeah , Thanks Muskegtracker for your intrest. By the way It's a 1.3 Tin Top  87 Samurai.
"WORK SMART NOT HARD"

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Offline wildgoody

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #5 on: November 17, 2009, 02:22:15 AM »
As long as you don't have a backfire your intake system will stay intact, but an intake
full of gas and air, plus the heat from a turbo could end in a bang  :o

Wild
Real Trucks Are Built, Not Bought,
And Chrome Don't Get Ya Home.  

An armed man is a citizen. An unarmed man is a subject.

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Offline one mile

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #6 on: November 17, 2009, 04:50:23 AM »
Good point....I'll have to go easy on timing.
"WORK SMART NOT HARD"

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Offline muskegtracker

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #7 on: November 17, 2009, 09:11:52 AM »
With my turbo setup (1.6 FI Tracker) I'm running mild boost (6 psi) and I've seen a dramatic decrease in fuel economy. :( 
But the new found acceleration and passing power are great! >:D
91 Chevy Tracker
2.7L V6, Coil-over Suspension, ARB, and other goodies...
My build - http://www.zukiworld.com/forum/index.php?topic=25353.0

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Offline one mile

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #8 on: November 17, 2009, 10:43:22 AM »
Was the decrease caused by your right foot or did it really suffer even with 5 lbs of boost? I will be driving back and forth to work and gas mpg 's are important to me in this particular build. Did you make and other mods to it with the Turbo set up? Does the ECM run it rich or somthing? What mpg's are we talking about anyway? Maybe I will have to go the old fashon way like I said before.......... Did you buy aTurbo KIT or build it yourself?
"WORK SMART NOT HARD"

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Offline muskegtracker

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #9 on: November 17, 2009, 11:32:06 AM »
Was the decrease caused by your right foot or did it really suffer even with 5 lbs of boost? I will be driving back and forth to work and gas mpg 's are important to me in this particular build. Did you make and other mods to it with the Turbo set up? Does the ECM run it rich or somthing? What mpg's are we talking about anyway? Maybe I will have to go the old fashon way like I said before.......... Did you buy aTurbo KIT or build it yourself?

I built it myself.  We're talking like from 25 mpg to 18 mpg or maybe even less.  That is at 70 mph on the highway.  Even driving careful around town (which is where I usually get the best gas milage) it was noticably worse.  Actually when I decided the do the turbo I had hoped that it would remain close to the same as stock.  oh well.   My setup runs as stock when not in boost.  Around town I can drive most of the time without boosting, or very little.  I'm sure it has to do with the extra injectors I had to plumb in.  They only run at 4psi or higher, but they're like a big secondary some over fueling at first opening.  So, if this makes no sense, basically my theory is because the turbo is pushing more air in, even at below +psi numbers, than stock, the computer adds more fuel to compensate.  Savy?   ???
91 Chevy Tracker
2.7L V6, Coil-over Suspension, ARB, and other goodies...
My build - http://www.zukiworld.com/forum/index.php?topic=25353.0

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Offline fischenr

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #10 on: November 17, 2009, 11:49:40 AM »
In my humble opinion a draw through is simple and will be adequate for a few psi. A couple stock draw through factory set ups came out on some gassers with 4 barrel carbs, for example a buic regal(im pretty sure?). The biggest advantage i think is gonna have to be you dont need any sort of compensation to richen the mixture under boost, so no carb mods to solve 'leaning out' problems like you would run into on a blow through set up. Its been tried and tested, for what its worth, no factory gasser ever produced has had a blow through(from what i know), they have all been draw through.

A few dissadvantages are more lag, and the longevity of the turbo. The seals on the intake side of the charger are prone to going bad after a wile because most turbos you find arent designed to run with the vaccume thats gonna be created when the butterflies are closed. But i dont have any first hand experience with this so i dont know how long they will stay good.

I probably would encourage it: most importantly its basically a bolt on mod (no carb mods to hassel with), personally i wouldnt worry too much about your turbo seals because the vaccume created by the little fella isnt gonna be  super massive,

its an easy set up at the sacrifice of lag and and the ammount of boost you can run, its not the highest performance way to charge an engine, but it'll be effective and fairly problem free

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Offline wildgoody

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #11 on: November 17, 2009, 06:46:20 PM »
Dramatic fuel economy decrease, that's what I was getting running 33" Swampers
and an auto trans with the turbo. IMO it's a fair trade off.

And as far as vacuum on a little engine, same as a big one, about 12-13 inches
vacuum at idle. The big problem is the oil getting sucked from the bearing area
and getting burned as smoke trails out the exhaust.

The turbo will increase power even if there is no boost, a condition of 1" to 0"
vacuum is "boost" compared to 2-3 or even 4 " in a non turbo setup at WOT

Wild
Real Trucks Are Built, Not Bought,
And Chrome Don't Get Ya Home.  

An armed man is a citizen. An unarmed man is a subject.

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Offline muskegtracker

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #12 on: November 18, 2009, 09:36:19 AM »
Dramatic fuel economy decrease, that's what I was getting running 33" Swampers
and an auto trans with the turbo. IMO it's a fair trade off.

And as far as vacuum on a little engine, same as a big one, about 12-13 inches
vacuum at idle. The big problem is the oil getting sucked from the bearing area
and getting burned as smoke trails out the exhaust.

The turbo will increase power even if there is no boost, a condition of 1" to 0"
vacuum is "boost" compared to 2-3 or even 4 " in a non turbo setup at WOT

Wild

Well said!  ;D
« Last Edit: November 18, 2009, 09:44:13 AM by muskegtracker »
91 Chevy Tracker
2.7L V6, Coil-over Suspension, ARB, and other goodies...
My build - http://www.zukiworld.com/forum/index.php?topic=25353.0

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Offline one mile

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #13 on: November 18, 2009, 10:36:48 AM »
I like the input! The next step ,does anyone know of a factory "Junkyard" Turbo that maybe a candidate for this set up? I mean that I could use to see if I want to go deeper (into my pocket) and buy a new Turbo after I work the "Bugs" out of my R&D Setup with the used one?
"WORK SMART NOT HARD"

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Offline wildgoody

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Re: Want to build Drawthrough Tubbo with 40mm CV carb
« Reply #14 on: November 19, 2009, 02:54:08 PM »
Subaru 1.8L turbo wagons from the mid 80s are out there, those are
non intercooled so the boost is set to 7 PSI, works well, no lag cheep
to rebuild

Wild
Real Trucks Are Built, Not Bought,
And Chrome Don't Get Ya Home.  

An armed man is a citizen. An unarmed man is a subject.