[409guy]

the other day i was at a car show and saw a chevy 350 with a single tubro on it. the way the guy ran it looked very simple and CHEAP , it appeared as if he got a factory exhaust manifold and flipped it up side down and had a flange welded to it, the turbo of course was on the flange, the thing that got me is he ran the turbos compressor outlet to what looked like a 2 carb spacers with a pipe welded to it,that sat right under the carburater.... would you have to get the carb prept (spelling?) and what else would you have to do to make this work. keep in mind its on a budget... i mean this guy didnt have an intercooler or anything! sorry if this post is hard to follow, BUT MY MIND IS BOGGELED!

[xntrik]

Originally Posted by 409guy

the other day i was at a car show and saw a chevy 350 with a single tubro on it. the way the guy ran it looked very simple and CHEAP , it appeared as if he got a factory exhaust manifold and flipped it up side down and had a flange welded to it, the turbo of course was on the flange, the thing that got me is he ran the turbos compressor outlet to what looked like a 2 carb spacers with a pipe welded to it,that sat right under the carburater.... would you have to get the carb prept (spelling?) and what else would you have to do to make this work. keep in mind its on a budget... i mean this guy didnt have an intercooler or anything! sorry if this post is hard to follow, BUT MY MIND IS BOGGELED!

Budget and turbos are mutually exclusive terms.

A turbo "blows through" a carburetor not under it. And yes it takes a very special carburetor. The best blow through set ups are like the original Shelby cars with centrifugal superchargers with the carb mounted inside a big box.

Turbo cars easily melt down if the tune is not perfect. Turbos are not something easy to deal with, but they are fun to drive.

[weirdbeard]

I have always wondered why when using a centrifugal super charger or turbo with a carb. why cant it blow into an adapter under the carb.? It seems like it would make things more simple and no special carb. Like with a roots blower or screw type super charger the boost takes place below the carb. What am I missing?

[matt167]

generally, the only modifications are they drill out jets bigger and some ports bigger and run a boost refrenced fuel pump ( the vent has a brake line attached to it that runs to a place on the engine that will see boost, this increases fuel preassure accordingly ), this is on a blow through setup ( weather it be turbo or a centrifagul supercharger ), a draw through setup is much simpilar, but you need to fabricate a carb flange on the intake side of the compressor and put carbon seals in the compressor, in this case, a 750 Rochester QJ with a externally refrenced power valve would be perfect ( they were used on the draw through Turbo Buick 3.8's ). a 3.8 draw through turbo would be too small, would boost up with no lag, but being so small for a 5.7L could actully overboost. I have a draw through 3.8 Buick turbo that I got free, it will find it's home on my '67 Falcon 200 I6 once I get all the parts

[weirdbeard]

Matt what is the deal with the barn star? Does it have something to do with the Illuminati? I want in. I wont tell anybody.

[farna]

The first problem with that cheap setup is only one turbo mounted on one side of the engine (I'm assuming it's a V-8??). The second is where the turbo dumps into the manifold. I suppose if the under carb adapter is tall enough air could be directed down, but there is the potential to compress the air in the manifold and blow back out of the carb as well as into the engine. The air will take the path of least resistance. An intercooler isn't necessary for low boost applications. I would assume that this thing is low boost to keep from blowing out of the carb. At higher boost (8-10 psi or more?) it could. This setup has to deliver no more pressure and volume than the engine can suck in or there would be a big problem! But at 4-5 psi it might work. I would think it would work more like a big vacuum leak under the carb though. A suck-through system doesn't because there's only one direction the air can possibly go -- it can't go back through the carb becasue there is no pressure under the carb itself -- the pressure's at the other side of the turbine. With a blow-through system the pressure is on both sides of the carb, no pressure differential to cause problems.

The old blow through systems had the carb in a box because the carbs leaked to much. You can get Holley turbo prepped carbs now that don't need the box up to 20 psi. I'm not positive it's a special carb -- all the Holleys may be made that way now.

[53_belair]

The carbs are not all that special, just some diffrent seals to handle the extra pressure on the carb. I have seen a few sbc turboa setups like the one above, I belive they are called draw through. Its explained in the book, turbochargers by Hugh McInnes. I will have to go home and dig out the book for a better explination, but I do HIGHLY recomend the book to any one thinking about going turbo in the future.

[orangef4]

I think the system you saw was a drawthrough setup. The spacer you saw takes the fuel/air through the carburetor, then directs it to the turbo inlet, and then takes the charge from the compressor outlet back into the intake manifold. These systems were marketed by Accel I believe. They have been discussed on here before, so a search should turn up more answers.

[lowROLLERchevy]

Originally Posted by xntrik

Budget and turbos are mutually exclusive terms.

A turbo "blows through" a carburetor not under it. And yes it takes a very special carburetor. The best blow through set ups are like the original Shelby cars with centrifugal superchargers with the carb mounted inside a big box.

Turbo cars easily melt down if the tune is not perfect. Turbos are not something easy to deal with, but they are fun to drive.

not to pick on you, but theres some things that need clearing up

budget turbo setups are possible. ive seen people turbo cars for $100 before. its all about what u have available to you and how u use it

the carbs arent that special, mostly they are just modified to supply enough fuel at the right times, as a turbo cars fuel curve is different from an N/A cars curve

its actualy quite hard to melt an engine down, buy a wideband o2 sensor ($300) a pyrometer ($100) and diasble the spark advance (untill its tuned) and your on your wy to having aboosted car that u cant blow up, as long as u keep the gauges "out of the red"

the latest car i turbo'ed has at least 50 1/4 mile pulls on it ... and it only has a 30 minute base tune on it.

turbos are easy to deal with

EDIT:

check out Turbos10's gallery
check out the turbonetics turbo selection PDF HERE for turbo sizing reccomendations.

[454C10]

Yes, sounds like an old draw through system. The tall spacer under the carb is divided into two parts. The turbo sucks air and gas from under the carb then pressurizes it and forces back into the engine through the bottom side of the spacer. This allows the carb to be in the stock location, just higher.

Can't inter-cool that setup but the fuel going through the turbo will cool the charge.

I found an old hotrod magazine where they installed one of those on a 454 truck. They even claimed better mpg which I kind of doubt, but who knows.

[matt167]

Originally Posted by weirdbeard

Matt what is the deal with the barn star? Does it have something to do with the Illuminati? I want in. I wont tell anybody.

you get a barnstar if you contribute to the Wiki Pages. I put in a little info on regestering/titiling a car in Ny

[xxllmm4]

The DYI cheap turbos are coming of age and with the amount of information avaliable it should be fairly easy to do a inexpensive setup that works. If you can do the fab work yourself, use rebuilt or good used parts you can really keep the costs down. Add some cheap used intercoolers, water injection and you should be pretty safe.

I was talking to a local shop owner who is doing my roll bar about this very subject. There is no reason the ready made kits should be so expensive. His plan is to make his own kits for mustangs for $2500 installed!

Jordon

[409guy]

Do you know where i could find a spacer like that, that would bolt up to a demon? or do you think that if i made it a blow through that a demon could hold the pressure... here is a simple diagram that i think i might try to fab up, i figure if a get a shorty header and flip it upside down, weld a turbo flange to it, than i have my self a turbo manilfold. the car i would be putting this on is a 71 pontiac 400(punched out to 461 thanks to a jim butler stroker kit) that has 100cc heads an an estimated 8:1 compression. i think that i could make some good horsepower for cheap