26 (edited by jrbe 2013-05-29 04:32 PM)

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

The lips of the seals can flip (not like ingesting the seal) or silicone sealant can be sucked in. Cork etc can be sucked in too. Most likely the seals will leak air in and it wont get to that high of a vacuum. Thin oil pans can deform and choke off the oil supply etc if vacuum gets too strong. Give it a try if you want.

Some vacuum is definitely helpful in the crankcase but too much can cause problems.

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

I know that this is an old post, but I see people talking the most amount of BS.
I have been drag racing a draw thru vw air cooled beetle for more than 20 years.
My engine is a 2 litre and it is making 440 hp. It has been done by lots of people from way back in the 70s. There was guys doing 8 seconds in the 1/4 mile and even today they are still doing those times.
I am running over 28 pounds of boost in my car. And there are guys using much more, and with great success.
You don't need blow through or fuel injection to successfully turbo a car.
I also don't know how any carburettor system can create any vacuum in the engine... That is just stupid. An oil seal is designed to seal oil from getting out of an engine, not for stopping air from getting into the engine. All seals will let air get in, under vacuum.
I would not be pushing much more than 10 psi through a circuit race engine, as you would need better fuel control and water, alcohol injection.
Remember, that a carburettor is designed to be used with out boost going through it, so it is functioning as it was designed to, when using it in a draw thru set up.
Blow thru needs much more modifications to make it work properly. You can buy a very good blow through Holly carburetor now, but you need much more than the carb to make the system work.

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

Nice first post.

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

h.ortlepp_jpo wrote:

I know that this is an old post, but I see people talking the most amount of BS.
I have been drag racing a draw thru vw air cooled beetle for more than 20 years.
My engine is a 2 litre and it is making 440 hp. It has been done by lots of people from way back in the 70s. There was guys doing 8 seconds in the 1/4 mile and even today they are still doing those times.
I am running over 28 pounds of boost in my car. And there are guys using much more, and with great success.
You don't need blow through or fuel injection to successfully turbo a car.
I also don't know how any carburettor system can create any vacuum in the engine... That is just stupid. An oil seal is designed to seal oil from getting out of an engine, not for stopping air from getting into the engine. All seals will let air get in, under vacuum.
I would not be pushing much more than 10 psi through a circuit race engine, as you would need better fuel control and water, alcohol injection.
Remember, that a carburettor is designed to be used with out boost going through it, so it is functioning as it was designed to, when using it in a draw thru set up.
Blow thru needs much more modifications to make it work properly. You can buy a very good blow through Holly carburetor now, but you need much more than the carb to make the system work.


And how does drag racing an aircooled  VW engine relate to Lemons racing? 
Apples and oranges!
How much money and time & development has gone into your engine set up?
We're racing $500 crap cars.

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

jimbbski wrote:

And how does drag racing an aircooled  VW engine relate to Lemons racing?

Drag racers live their lives a quarter mile at a time.
Sometimes (myself included), Lemons racers have engines that do the same.

-g

Myopic Motorsport's #888 Ceci n'est pas une Citron Thunderbird ("This is not a lemon" but a 1995 tbird w/ 93 V8 swap + shopping cart rear wing + engine mounted frito maker)
2017 Sears Pointless Organizer’s Choice
Frito Making Tbird from 2018 Sears Pointless Engine Heat BBQ - http://goo.gl/csaet4

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

He did mention for longevity ("circuit race") he would stick to around 10 psi or less.  Which seems reasonable  That's still roughly a 50% bump in power over naturally aspirated.  And as draw-though is a much simpler solution than blow through, it should cost less.  Really, as long as the turbo can deal with gas being sucked through it, and the carburetor can deal with the HP levels, everything should be fine.

Tunachuckers: 15 Years of Effluency
'08 - '10: 1966 Volvo 122, "Charlie"
'10 - '18: 1975 Ford LTD Landau --> 2018 - current: Converted into 1950 "Plymford"
'22 - current: 1967 Volvo 122, "Charlie ]["

32

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

Update mechimike? It's been 4.5 years since you asked, have you executed your drawthrough turbo yet? If you still want to "Turbochargers" by Hugh MacInnes is a good read, it's from 1984 but is the best book on the subject, and since it's from 1984 it has details about drawthrough among other designs.

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

Since I have more time to read than to wrench, I may pick up that book at some point and give it some thought.  At this point, though, we're focused more on cubic inches rather than forced induction.

Tunachuckers: 15 Years of Effluency
'08 - '10: 1966 Volvo 122, "Charlie"
'10 - '18: 1975 Ford LTD Landau --> 2018 - current: Converted into 1950 "Plymford"
'22 - current: 1967 Volvo 122, "Charlie ]["

Re: Draw thru Turbo w/ Carb Question, Disappointing Replies

draw thru carb setup becomes much easier when the fuel is propane. just sayin'....

"THE WONDERMENT CONSORTIUM"
Everything dies baby that's a fact,
But maybe everything that dies someday comes back?