carb before turbo?

[Bjorge1]

Is it possible on a turbo sled to install carbs before the compressor? I think it would make things alot easier? I would vent the BOV line back between the carb and compressor? Then you wouldn't have to worry about run on and pressurizing the bowls and slides? Just an idea?

 

[triple7]

The issue I see with a draw through system on a sled is the length of intake tract from the carb to turbo to crankcase. I think lag would be huge from the time you open the throttle to the time you see the motor come to life. JMO

 

[PTE800]

Contact these guys, They already have kits for a few models. The RX1 that I rode definately had NO lag at all. The guy that has it says that it is very simple and easy to tune. Here's the link http://www.lightningprollc.com/?page=home

 

[AKSNOWRIDER]

Is it possible on a turbo sled to install carbs before the compressor? I think it would make things alot easier? I would vent the BOV line back between the carb and compressor? Then you wouldn't have to worry about run on and pressurizing the bowls and slides? Just an idea?

they used to do car motors like that...turbo lag was terrible and no one ever really figured out a way to cure it..or even make it tolerible....also you run the risk of igniting the fuel charge if the turbo gets hot enough since the mixture is so compressed....

 

[triple7]

The above links system LOOKS solid. It would have all the benefits of a draw through system and easy tuning would be one of them because basically you are just making the carburator think it is hooked to a bigger motor. On the RX1 it looks like the arrangement would be possible to minimize lag. On a two stroke sled there would be too much intake length from carb to crankcase and I think on the nytro the same thing would apply.

Dont get me wrong, I think that a draw-through system could be a superior setup to a blow through if done correctly and the application allowed for proper fitting...I just question whether or not snowmobiles meet those requirments.

Jake

 

[Bjorge1]

Very good point, I thought about that last night and what if I put a butterfly valve in the intake tube right before the intake ports. for instant throttle, I would have to sink the carbs and butterfly but it might work and with the BOV valve cycling back between the carb and compressor i would have a fresh charge always cycling. Another good point is that the compressor would vaporize the fuel better. Like I said before, only an idea. but might be worth a shot.

 

[Boyko]

Draw trough systems have a lot issues and that is why you do not see them. There is a lot of smart people that building turbo kits and there are reasons that you do not see draw through systems.

On a sled you will have to deal with carbs icing up even if that are heated.

You will be creating a huge vacuum before the turbo when you get off of boost and will be sucking a wack of oil out of the turbo and into the intake track. You need a special turbo for this application so you are going to be limited for choices of turbos.................................. if you can find one.

An intercooler is out of the question unless you are into driving a bomb around.

The problem with lag is you are choking the turbo when you are not wide open and you can not have it spooled and ready to go with a blow off valve open when you not on boost like on a blow through system.

The idea of cycling the charge between the carb and the turbo will cause a extreme rich condition. A BOV relieves pressure not vacuum.

I know draw through systems have been done before but a blow through system works very well and is the standard for applying boost utilizing carbs.

 

[Bjorge1]

thanks for the insight. nice to talk to people who know what is going on. new to turbo's, but thought it was worth some criticism. what are people doing then for carb's? using stock carbs or are there blow through carbs that can be used on sleds?

 

[triple7]

Stock ones modified a bit mostly.