Been thinking about doing a turbo for a little while now, bought Maximum boost and turbochargers by Hugh MacInnes, and basically I am wondering if anyone has any experience with draw-through turbo setups?

The main drawback seems to be icing, but I live in florida where its hot all the time so that is not a major concern, and if anything I could just run some aviation gas (emission laws have been repelled, so no catalytic convertor, thus leaded aviation gas with anti-icing agents would be possible).


With the drawthrough how do you deal with enrichment under boost? or is there no need cause the carb works the same as on a Naturally aspirated engine?


How big of a carb do you need for a draw through setup?

 

The big problem with drawthrough in our cars in the packaging. you need to have the route from the turbos to the carb and the motor very short. Basically, the turbos have to be over the valve covers or close to it....not much room there.

Drawthrough carbs require tuning of course, but nothing special, no modifications.

 

ATI sells a boost referenced mechanical fuel pump for carb setups. basically you run a vacuum line from the carb hat to the fuel pump, so that when the boost comes up the fuel pump keeps the fuel pressure up.

 

Yep thats for blow through.

There are lots of fuel problems with running a draw through... the low pressure pulses the carb sees will be weaker because of the turbine in the way and the distance from the cylinders. Because of this part throttle tuning will be hard to get right. There will be also be puddling issues causing fluctuating rich lean conditions and surging. I think you will also have throttle response issues because of the distance between the carb and cylinders. WOT shouldnt be all that hard to get right though.

I think the whole reason turbos got a bad name and took so long to catch on is because of the driveability issues with draw through setups. If I were to go with a carb I'd go blowthrough.

 

Thanks guys, still investigating setups but this inquiry was inspired by an 800hp 3.0 Liter Chevette I saw at a car show over the weekend.

Seemed to be working pretty good for him but he admitted to working out all the problem on an engine dyno before putting in the car.


Edit- 500hp Turbo with just the turbo, 800hp with Nitrous.