[mychevystang]

I have been thinking about turbo charging my motor...
A few problems
I have a carburetor and around 11.5:1 compression motor.
can I put a turbo on my motor with that kind of compression, even running a low boost. If I use 100 octane fuel is it possible.

I seen turbos10's truck, I also have an s10 but am curious if running the shortie headers is a killer for the power instead of going with the long tubes. Is it even possible to use the long tube headers and fit all the curves of the exhaust required for a turbo in it.. what is the cost I am looking at. If I could get a procharger for around the same price I might as well get a procharger.

thanks for any info, and If I am crazy for even wanting to try this let me know...

 

[Siggy_Freud]

Well I dont pretend to know a whole lot about turbos, I dont think that it would be very beneficial to run a turbo with that sort of compression. Even if you could run it, I dont know how long your (what I assume) stock bottom end could handle the overall compression with the turbo running.

Seems like you'd be spending a lot of dollars for very little gain. If your going to turbo it, build the motor with a turbo in mind.

 

[mychevystang]

the bottom end is not stock.
wiseco 8cc domed pistons
72cc victor jr heads
eagle h-beam rods
steel crank.

since it is winter time i could change the pistons to a lower compression but wanted to know what the pros think.. would i be able to run high boost at the track with race fuel and then turn the boost down and run 93 octane mixed 50/50 with race gas...

 

[firestone]

You might be able to do it and make a little more hp, you would be so limited on the amount of boost you could run even if you had an intercooler, that I think it would be an inefficient way to spend your money. My guess is that you would be limited to 4-6 lbs of boost, mabye 8 at an absolute max. That really wouldent give you a whole lot more hp for the $4000 -$6000 you would be spending on the kit and installation.

Adam

 

[TurboS10]

You have too much compression for boost.....period. You need a set of dished pistons to do it. I have less than $800 in my turbo/wastegate/BOV/headers, but I fabricated everything and did alot of bargain shopping on ebay. Buy everything new and you will hit the 3-4k mark.

Chris

 

[mychevystang]

turbo

I am sure I can fabricate the pipes. is there anything special I need for the carb. I know I will need an encloser and a vacuum controled fuel pressure regulator. anything else I will need besides the turbo, and wastegate.. Turbs10, what headers did you use or did you ahve to fabricate them too... I was thinking of getting the 1 3/4 inch shorties and turning them upside down..

 

[TurboS10]

I used a pair off of a malibu or something. I just cut all the tubes apart, separated the flanges and started welding. My headers are not beautiful but they were cheap at $30 on ebay brand new.

You also have to have nytrophyl floats in the carb and some will say you need to devise a way to seal the throttle shafts. If the shafts are still tight sealing is not a real big deal. The high speed airbleeds typically need to be reduced to keep the mixture from going rich under boost. A proform body will give you adjustable bleeds, but some have had luck using a small wire as a restriction in the bleed itself. I personally have not messed with that.

Chris

 

[virrix]

Wow, didnt think you could turbo a carbureted engine...this gives me new ideas, heh.

 

[1BAD80]

Here is the site for a Holly carb.
http://www.hangar18fabrication.com/blowthru

 

[87442lover]

Wow, didnt think you could turbo a carbureted engine...this gives me new ideas, heh.

More or less you will be making a jerry rigged TBI setup out of your carb. no off the shelf carb will work in a blow through setup.

Everyone does'nt want to hear it, but I dont recommend using a turbo, or centrifugal charger on a carbed setup.

If you are going too than you need to fab up, or find a turbo setup off of a pontiac 301 turbo, or buick turbo pre-83 for a pull through system. I think This may not be the best setup for all out performance, but it is the way the manufactures sold these turbo/carbed automobiles. I would'nt trust a blow through setup with a carburator on any day of the week.

This is the setup I would use.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33742&item=7930680654&rd=1

 

[dmc12mk3]

Seems to me that 'any' carburetor would work, provided that the pressure on the outside of the carburetor were the same as the pressure of the air you're forcing through the carburetor.

87442, can you give any reasons as to why this is not true?

 

[87442lover]

There are many reasons, and no I really dont want to get into an argument... again.

A few simple reasons are:

Carburators work on vacuum, that is the negitive pressure through the Venturi (however spelt) to force the fuel out and mix with the air like a perfume bottle for a very rough example.

When boost is applied, odd things can happen, fuel can actually be pushed back out of the carb, it can run extremely rich, the float can crush, etc.

When you modify the carburator you are basicly converting it to a crud form of a fuel injection setup to where fuel is no longer metered by the carburator, but more or less pushed out into the air stream.

I'm not going to go into it any further because we've had this conversation too many times. Just dont start getting sassy and we wont get into it.

In my own opinion, and feeling, I would never use this kind of blow through setup. A pull through system is scary enough considering the rich air/fuel mixture is getting pulled through(a HOT turbine wheel) and then compressed by the turbo. I have the parts to build a pull through system right here as I was goign to do so on my 84 cutlass, but I just dont trust it too much. If I was going to move up to a super/turbo charged setup the first thing I would do is buy a TBFI setup, or steal one off of an old GMC as these are perfect for forced setups. But as for a carbed setup....

I just dont like the idea.

BTW, I do still have all those parts just sitting around still. Dont know if I'll ever use them.

 

[TurboS10]

Look at the link that 1BAD80 sent. A 9 second turbo car running a carb should be proof enough for anyone that it is plenty doable. The carb is not turned into a TBI or anything even close to that. A carb works be pressure differential from atomosphere(~14.7 psia) and the vacuum in the engine and by the speed of the air flowing through the venturis. By applying boost you simply increase the absolute pressure of the system and the velocity of the air through the venturi. Increasing the velocity through the venturi will stregthen the fuel signal(read up on venturi effect) and increase the fuel flow into the air stream. The pressure difference also increases the pressure at the air bleeds which will affect the fuel curve and thus will need some tuning.

There are alot of guys successfully running blow through setups and they are many times better than draw through for multiple reasons. I do now know of any turbos large enough for a V8 that are designed for draw through and thus having the proper carbon seal to prevent fuel/oil mixing at the turbo.

And BTW, fuel/air is not drawn through the turbine in a draw through setup. It is drawn through the compressor.

If you need any help when you decide to do this PM me. I can point you in the right direction without the distracting noise here.

Chris

 

[dmc12mk3]

Thank you for the information TurboS10. I have been shown several turbo'd mustangs that were running plain jane carburetors, so I knew it had to be doable and an explanation of "it can't be done because I don't feel right about it" doesn't suit me. I just wanted to get a better idea as to what was going on with a setup like that. Thanks!



btw - so if you enclose the carburetor and pressurise the whole system so that the air outside the carburetor is pressurised...is simply the speed of the air running through the carb what you are tuning against vs how it would behave in an open atmosphere environment?

 

[mychevystang]

turbo s10

I think over this winter the best thing I should do is get an injection system and lower compression pistons. Then I can worry about a turbo. I am sure my solid roller cam with .575 .575 lift and 255 degrees of durations isn't the best for a turbo either. if someone has advice on that let me know..

 

[orangef4]

I have a blow through turbo set up on my truck (86 Chevy C10). It really is not that difficult to make a carburetor work in this fashion. The link 1BAD80 provided is a great starting point. Mine performs great, and I have had no problems with it whatsoever. It will require some tuning, but so does everything else. There is a lot of good info at the TurboMustangs.com "Carbureted Turbo Tech" forum.TurboMustangs.com A member of that board has run a 7.86 quarter mile with a blow-through carb. Is that enough proof they do work?

As far as the cam, what is the lobe separation angle? The general "ideal" is to have a wide LSA to limit overlap. What is your goal for the motor?

If you have any more specific questions about the carb, feel free to ask.

 

[mychevystang]

turbos charging a carburetor

the lobe seperation is 110. I built the motor to last and be capable of putting my s10 in the low 10's. I know that is possible with just motor and little nitrous but it is way better to use a turbo or supercharger. I wouldn't be disipointed if it could run in the 9's but that is not a goal of mine.. running that fast would require more money in the suspension that I have to spend..

 

[TurboS10]

With that duration, 110 is way too tight. If you were in the 114-115 it might work, but 110 is just too much overlap. If you really want to make some power, you will want a 240 dur. range cam with 114 or so lsa. That range cam will let you run alot of boost and will make huge power if you want to do so some day. I would guess 800-1000 HP with a cam like that and 20-25 psi.

Chris

 

[1BAD80]

Here is a site for all turbos/superchargers for comparison.
http://www.proficientperformance.com/procharger_superchargers.htm