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Discussion Starter #1
Draw through turbo.
I have read this here and there while browsing. Can't get a clear description of what it is.
Can somebody explain what it is as compared to a traditional turbo please?

Also, I saw the pix posted a week or two back of a twin cam swift motor in a sammy with the swish turbo.
Does the swift need low comp pistons to run the turbo, and if so, where and what?

Any help appreciated.

Paul.
 

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Draw through is just that.. the carb is on the vacuum side of the turbo. The fuel and air is pulled through the carb and run through the turbo.. then pushed into the engine.

As far as the Swift.. lotta answers to those questions here. www.teamswift.net
 

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Thanks Rob, I spent a bit of time on that site. Boy are those dudes petrol heads.
I have access to a small motorcycle turbo and was thinking of trying it on. But as I have the Gti short block with an eight valver and don't want to buy low comp pistons, well I guess it's not worth the effort.
I initially thought of using it with low boost just to perk up the performance a little.
Oh well, any other thoughts on what to use the turbo for? A hair dryer maybe?
Paul.
 

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Thats probably going to be to small. Iv been doing alot of research on this. A garret T3 or a IHI off a ford probe or mazda 626 should do the trick. You want something off a larger displacement due to the air fuel mixture being a bit thicker. Im thinkin of going with a buick regal turbo. It's the only T3 Iv found so far (or at all for that matter) that has an adapter with studs. Id just have to make an elbo that will adapt it to the carb. AUSSUMING it will hold. Witch might be a little far fetched. I think I might have to hook my welder up for aluminum and make one with a stronger mounting.
 

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Well, hate to piss on anyones cereal.. but it's ALWAYS better to go too small than too big with a turbo setup. Period. End of discussion.

There are some T3's out there with decent A/R's.. .48-.49's... but I think anyone turbocharging a 1.3L SOHC Zuk motor would be much better served by a smaller IHI turbo or a T25.
 

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It's not always going to be better to go too small. It depends what your goals are. For a street driven Samurai smaller may be better. But you don't want it so small that it pushes nothing but hot air after 3500 RPM at your desired boost level. This is something you'll especially want to avoid in a draw through setup because an intercooler can't be used. A T25 may work good though. They can be found in good condition off of 95 and up Talons and Eclipses because the owners of those cars like to refer to them as T-too-smalls and usually upgrade them. Like me. :D
 

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Run 8 to 1 compression ratio. Intercooler isn't necessary for single digit boost. Consider rigging a simple water or alcohol spray system (you can use a washer fluid pump). In the turbo plumbing, rig a pipe section that has a radiator cap attachment. You can use it as a cheap pressure relief valve, and vary your boost by switching caps. Draw thru works well with carbs but you will get much better results by seriously oversizing the carb. It will flow better and provide the required additional fuel.
 

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I have never turbo'd anything, so don't flame me, I am just askin'

ccj8008 said:
In the turbo plumbing, rig a pipe section that has a radiator cap attachment. You can use it as a cheap pressure relief valve
Isn't this a potential fire hazard? All of that nice air/fuel mixture flowing around the engine bay at high boost?

Draw thru works well with carbs
That reminds me of the old ads I usta see for a compressed air line that screws into one sparkplug hole. Just run the engine and inflate your tire. Dunno, it sounds like the tire becomes a bomb to me. So.. do the draw-through setups ever let loose and go 'BANG'?? I don't know anything thereabouts to set it off.. just wondering.
 

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run a 14b off a dsm, its a bit bigger than the t25 and doesnt just blow hot air until about 5500rpm. The t25 is WAY to small, not efficent whatsoever.
 

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A 14B or T25 from any of the DSMs would probably work OK. They actually might be a bit on the large side depending on what you are trying to do. If you have just a 1300 and want to run 6 or 7 psi and want the boost by 2500 RPMs, they may be too large.

14Bs are in Lasers, Talons and Eclipses from 1990-1994. The T25 is in the 1995 to something like 1999 cars. I would probably go for the 14B as it has a whole family of similar sized turbos that are the same setup. The T25 is a bit of an oddball.

As I recall either the Starion or the 3000GT had the smaller 12B turbos if you wanted a smaller turbo.

All of the above turbos are good units that have both water cooled and oiled bearings. You will have to find a good oil source for these. I don't think I would bother with any of the older turbos, and am not a big fan of the T3 T4 family of turbos. You best know what you are doing with them as that A/R is an almost worthless way of picking a turbo, yet all of the T4 folks love debating over A/Rs.

I do not think you will need to lower your compression ratio to take advantage of low boost turbo setups. But do expect the worst when you start bumping up the boost.

My DSM engine is a low compression turbo set up from the start. Let me be the first to tell you that low compression on a rock crawler sucks. I have about as much power at idle as a 1600 16 valve. Not much. But at 16 PSI of boost... Weeee!

-Wayne
 

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billj said:
What does a turbo give you that a 1.6 16V won't?!?!
Since the smart guys haven't answered, maybe you'll hafta git by on what I can offer (The pointy-headed non-turbo-experienced guy who read a book oncet)

- In theory, the turbo recaptures a lot of the heat energy left in the exhaust. This is one way that a turbo can add power and efficiency. The quieter exhaust is evidence that you have extracted heat energy from it.

- I think a turbo isn't ideal for a rock crawler because you don't have the great torque down low, as Wayne has explained.

- I think the turbo IS ideal for a rock crawler cuz you have the power for freeway travel, and the predictable power for crawling, below the power curve.

Wayne, why don'tcha just use one of them new-fangled variable combustion chamber-volume engines? You could have it all!

- A turbo makes a small engine perform like a larger one, when you need it. And even then, it retains some of the valuable thermodynamic characteristics of the smaller engine; for the same power output, a larger engine has more metal surface area exposed to combustion heat & pressure inside the engine. This allows the engine to lose efficiency through heat loss.

But the necessary lower compression decreases efficiency, in theory.

The folks who build radical engines for those mpg races (700mpg up...) wrap the engine and exhaust all the way to the tip in order to keep the heat in. They run them as hot as possible.

The automotive guys have been working on ceramic engines for a long time. They are in production for some weird applications which I currently disremember. A ceramic engine can be run MUCH hotter than a metal engine. Plus it is harder so is 'sposed wear better. They usta talk about them being much lighter than iron engines, and might be suitable for diesel aircraft engines.

I think, in theory, a hotter thermostat in my Sammi probably adds efficiency, but it may be too small to measure. Or not, I dunno!

- Some folks say that the turbo adds turbulence that 'mixes' the air/fuel more so that you get better combustion. I don't know one way or another about this... one of my ME profs experienced with plasma-gas-diffusion Uranium enrichment process with turbo pumps said otherwise though. I know that combustion chamber design has become a GIANT concern in clean engine design. Now they can model the turbulence and flame-front propogation via computers.

- While campfire wheelin' you kin say "Yeah, I slapped a turbo on it..."

GeoB

P.S. I know Toyota produced a variable vane-pitch turbo that under computer control would reduce spin-up time and could vary boost. Hadda series of vanes around the scroll cage that directed the exhaust at different angles against the rotor, and at different volumes. Wonder to whom we should assign that project? Wouldn't it be a kick to write the low-level code to control that for a Sammi?? And have the time to do it? [1]

If anybody knows more about these turbos, I'd like to hear.

[1] My 1st job outta college was applying computer control to industrial processes. I kept pinching myself and thinking, "They are paying me to do this?" :) But I am waay out-of-date now.
 

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George, the variable vane turbos have been around for a while. This is what Dan in Arizona has in his Isuzu Amigo. I think he lifted his from a Chrysler 2.2 application and it is controlled via vacuum or boost. I think they are reffered to as VNT turbos. hmm, did a quick google and found his install page:
http://www.houlster.com/amigo/turbo2/

I have heard of a number of computer controlled VNT style turbos of late, but I don't know much about them. I'd say the concept is darn good.. finding one to fit my motor would be a pain. Maybe the TD04 mod that Dan mentions would be close.

If budget was not an issue, I would take the 1600 16 valve over the turbo 1300. but if price was an issue... I would have to take a close look at the numbers. The turbo project would be fun to build and play with. :)

-Wayne
 

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How about a turbo AND the 1.6 16V? :eek:

Spidertrax is working on it now for their comp buggies. Tom tells me they are pushing upwards of 200HP but stress cracking the lower crank bearing caps IIRC. Only a matter of time before they 'kit' it (I hope). Personally, I would be a very happy camper with a turbo 16V and only 120-150hp. :smokin:
 
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