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busey
Samba Member
Joined: October 19, 2016
Posts: 420
Location: Sun City Arizona
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 Posted: Fri Jan 04, 2019 11:36 am Post subject: Blowthru vs/or Drawthru Turbo |
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| Looking for turbo insight, benefits and drawbacks for a mild 2litre; It seems as though a Drawthrough turbo sy$tem is ea$ier on the pocketbook than a dual-carburated Blowthrough for a weekend warrior. Also came across that a book called "Turbomonia" by Bob Tomlinson is thee book to read to learn more about turboing a vintage aircooled VW motor. Problem is that damn book is so hard to find and the 1 or 2 out there are selling for $50-$80, WTF??? |
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Howard 111
Samba Member
Joined: July 09, 2005
Posts: 1827
Location: Virginia
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| Posted: Fri Jan 04, 2019 11:59 am Post subject: Re: Blowthru vs/or Drawthru Turbo |
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$50 to $80 is nothing compared to building a turbo motor that will last. Think long and hard about it before you jump in. Good luck!
_________________
1973 Karmann Ghia
Turbocharged, Fuel Injected
http://www.thesamba.com/vw/forum/viewtopic.php?t=531270 |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12678
Location: Western Canada
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| Posted: Fri Jan 04, 2019 12:00 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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That has been my experience. For a mild boost system it's hard to beat a draw through for simplicity and cost effectiveness.
Watch your head though! The blow through cowboys are going to ride in, guns blazing and shoot us down! |
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Krochus
Samba Member
Joined: January 01, 2017
Posts: 892
Location: NW Arkansas
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| Posted: Fri Jan 04, 2019 12:50 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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What are your overall goals and what do you have on the car now for carburetion?
_________________
1970 Turbo Baja Bug Turbaja 2165 t3/t4 Speeduino sequential EFI LS3 coil on plug ignition
1965 Chevy c30, Microsquirt turbo aluminum 5.3/nv4500 |
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busey
Samba Member
Joined: October 19, 2016
Posts: 420
Location: Sun City Arizona
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| Posted: Fri Jan 04, 2019 12:54 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| Howard 111 wrote: |
| $50 to $80 is nothing compared to building a turbo motor that will last. Think long and hard about it before you jump in. Good luck! |
Yep thats the purpose of this topic. Trying to get as much input along the way as nothing is set in stone so far and no deadline has been hammered out. |
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busey
Samba Member
Joined: October 19, 2016
Posts: 420
Location: Sun City Arizona
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| Posted: Fri Jan 04, 2019 1:04 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| Krochus wrote: |
| What are your overall goals and what do you have on the car now for carburetion? |
Mild naturally aspirated 2.0L with a pair of 44 Webers is what i currently do have to work with. Turbo powering it seems like a great way to get more bang-for-your-buck for a weekend warrior, than an all-out high compression monster street motor purchase? |
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Krochus
Samba Member
Joined: January 01, 2017
Posts: 892
Location: NW Arkansas
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| Posted: Fri Jan 04, 2019 1:08 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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Boost goals?
If under 10 psi you really are just a couple of carb hats, charge pipe, wideband turbo and boost ref fuel pump away from glory.
Either can be pretty easy to set up. But if you wanna use your existing stuff blow through will be cheaper
_________________
1970 Turbo Baja Bug Turbaja 2165 t3/t4 Speeduino sequential EFI LS3 coil on plug ignition
1965 Chevy c30, Microsquirt turbo aluminum 5.3/nv4500 |
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slalombuggy
Samba Member
Joined: July 17, 2010
Posts: 9143
Location: Canada
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| Posted: Fri Jan 04, 2019 2:08 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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I'm seriously considering a blow thru injection set up for my buggy. Tired of fighting with air density changes and the overall lack of air at Bonneville. Have been trying to read all I can on turbo combos and CB turbo/Gen4. Thinking of going to CNC Street Eliminator turbo prepped heads and an FK10 equivalent. Mark figures I could make an easy 320hp ?? at 10# boost. Then I could pull the engine and put it in one of my street cars and have some fun rather than look at it in the stand for 2 years between races. C-12 is $30 a gallon here. I'd rather run 91 pump gas......way cheaper to go for icecream. 
brad |
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Splitdog
Samba Split Personality
Joined: February 16, 2004
Posts: 4125
Location: Planet VW
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| Posted: Fri Jan 04, 2019 2:14 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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Turbo with FK10 will be no fun on the street after a bit.
_________________
CH³NO²
Z = z² + C
Der Blitzkrieg Kafers
#notacallooker |
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Maddward
Samba Member
Joined: July 18, 2010
Posts: 206
Location: Orange County, CA
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| Posted: Fri Jan 04, 2019 3:33 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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My draw through was pretty simple to put together but if you already have 44's I'd go blow through. I started with worn out 34 ICT's so I went draw through for simplicity and a little cheaper.
_________________
1959 Baja Bug, A-arm J30 Honda
https://www.thesamba.com/vw/forum/viewtopic.php?t=701787&highlight= |
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67rustavenger 
Samba Member
Joined: February 24, 2015
Posts: 9749
Location: Oregon
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| Posted: Fri Jan 04, 2019 4:38 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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Like Brad. I too have been spending a bit of time studying turbo setups.
My selfish reason is, cheap HP. 
On a drawthru system. You have to make sure that all the manifold piping slopes toward the heads with no low areas. If there is a location where fuel that fell out of suspension can puddle. It will! Then when you step on the fun pedal. The engine gets a huge blast of raw fuel. Causing a stumble and a rich black cloud out of the exhaust.
Also, drawthru systems are a little difficult at startup. Atomized fuel and air has to get past the non spinning turbo before entering the intake manifold.
With a blowthru system. The fuel and air arrive at the heads in an atomized state. Just like a normal carb setup.
On a drawthru system. When you snap the throttle closed. There is a huge amount of turbo vacuum pulling on the base of the carb. This vacuum will be pulling fuel thru the idle circuit. Unless the carb is correctly modified.
With a blowthru system. When you snap the throttle closed the BOV relieves the turbo pressure above the carbs. Throttle response is more like a carbed engine until the turbo builds boost. Then the fun begins.
Yea those books are spendy and hard to find. I bought Turbomania from the samba classifieds a few weeks ago. It reads like a DBHVW article. But has good information.
Also there is a thread on STF that explains turbo setup for the novice.
This thread was started by an acquaintance of mine and is very user friendly.
The upside of that thread is that almost of all the guy's that have responded here also participated in that thread.
https://www.shoptalkforums.com/viewtopic.php?t=108620
Disclaimer: I am not a turbo expert. If I have misquoted anything. You have my apologies. Up front.
Good Luck.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12678
Location: Western Canada
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| Posted: Fri Jan 04, 2019 4:40 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| busey wrote: |
| Krochus wrote: |
| What are your overall goals and what do you have on the car now for carburetion? |
Mild naturally aspirated 2.0L with a pair of 44 Webers is what i currently do have to work with. Turbo powering it seems like a great way to get more bang-for-your-buck for a weekend warrior, than an all-out high compression monster street motor purchase? |
Ya if you are set up with Webers already it makes little sense to start all over. Just keep the boost pressures low and very little needs to be changed. 4 -6 psi won't hardly even warrant timing changes, just fuel pump reference. There will be a kick in the rear that will put a big silly grin on your face too. |
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clonebug
Samba Member
Joined: January 29, 2005
Posts: 4027
Location: NW Washington
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| Posted: Fri Jan 04, 2019 4:49 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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So you are saying you personally know STV????
If so, Is he still alive and why did he drop off the face of the earth????
_________________
| vwracerdave wrote: |
Take a good long look in the mirror and report back on what you see. |
| Paul.H wrote: |
| That one line on that chart is probably better info than you can get from this place in a month |
My Megasquirt Fuel Injection Turbo Buggy Build
Water/Alcohol Injection
Audi TT intercooler
Upgraded to MS3Pro-Evo
EcuMaster PMU16
ECUMaster ADU5 Digital Dash
http://www.shoptalkforums.com/viewtopic.php?f=3&t=127936 |
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67rustavenger
Samba Member
Joined: February 24, 2015
Posts: 9749
Location: Oregon
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| Posted: Fri Jan 04, 2019 5:04 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| clonebug wrote: |
So you are saying you personally know STV????
If so, Is he still alive and why did he drop off the face of the earth???? |
An acquaintance.
I saw him last spring at the Avery's Aircooled car show. He was driving a RHD RatRod. 
I also did a cruise with him a few years ago.
I have no idea why he is no longer active on STF. But he is alive and still a fun guy to talk to.
In fact, He is the guy that peaked my interest enough on Dellorto carbs. That I have invested in more than a few sets over the last year or so. 
Next time I see him. If I remember. I'll ask why he fell off the STF earth.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12678
Location: Western Canada
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| Posted: Fri Jan 04, 2019 5:06 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| 67rustavenger wrote: |
Like Brad. I too have been spending a bit of time studying turbo setups.
My selfish reason is, cheap HP.
On a drawthru system. You have to make sure that all the manifold piping slopes toward the heads with no low areas. If there is a location where fuel that fell out of suspension can puddle. It will! Then when you step on the fun pedal. The engine gets a huge blast of raw fuel. Causing a stumble and a rich black cloud out of the exhaust.
Also, drawthru systems are a little difficult at startup. Atomized fuel and air has to get past the non spinning turbo before entering the intake manifold.
With a blowthru system. The fuel and air arrive at the heads in an atomized state. Just like a normal carb setup.
On a draw thru system. When you snap the throttle closed. There is a huge amount of turbo vacuum pulling on the base of the carb. This vacuum will be pulling fuel thru the idle circuit. |
Or you could put the throttle plates downstream of the turbo and the carb upstream (Impco) and run 120 octane fuel (propane) and solve all those problems including detonation up to 15 psi or more!  |
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Krochus
Samba Member
Joined: January 01, 2017
Posts: 892
Location: NW Arkansas
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| Posted: Fri Jan 04, 2019 5:06 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| oprn wrote: |
| busey wrote: |
| Krochus wrote: |
| What are your overall goals and what do you have on the car now for carburetion? |
Mild naturally aspirated 2.0L with a pair of 44 Webers is what i currently do have to work with. Turbo powering it seems like a great way to get more bang-for-your-buck for a weekend warrior, than an all-out high compression monster street motor purchase? |
Ya if you are set up with Webers already it makes little sense to start all over. Just keep the boost pressures low and very little needs to be changed. 4 -6 psi won't hardly even warrant timing changes, just fuel pump reference. There will be a kick in the rear that will put a big silly grin on your face too. |
No joke. When I went from a well tuned NA with my Weber carbs to 6psi boosted I didn’t even have to rejet or make any changes whatsoever to the carbs beyond adding pressure hats.
_________________
1970 Turbo Baja Bug Turbaja 2165 t3/t4 Speeduino sequential EFI LS3 coil on plug ignition
1965 Chevy c30, Microsquirt turbo aluminum 5.3/nv4500 |
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clonebug
Samba Member
Joined: January 29, 2005
Posts: 4027
Location: NW Washington
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| Posted: Fri Jan 04, 2019 5:12 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| 67rustavenger wrote: |
| clonebug wrote: |
So you are saying you personally know STV????
If so, Is he still alive and why did he drop off the face of the earth???? |
An acquaintance.
I saw him last spring at the Avery's Aircooled car show. He was driving a RHD RatRod.
I also did a cruise with him a few years ago.
I have no idea why he is no longer active on STF. But he is alive and still a fun guy to talk to.
In fact, He is the guy that peaked my interest enough on Dellorto carbs. That I have invested in more than a few sets over the last year or so.
Next time I see him. If I remember. I'll ask why he fell off the STF earth. |
He was a little before my time but I remember reading that thread way back when I was just peaking my interest in turbos.
I joined STF so I could actually see the photos in I think early 2007.
2 1/2 years later was when I posted my first build pic of some turbo parts I scored on at the April 2009 Portland Swap Meet.
Time flies.......
_________________
| vwracerdave wrote: |
Take a good long look in the mirror and report back on what you see. |
| Paul.H wrote: |
| That one line on that chart is probably better info than you can get from this place in a month |
My Megasquirt Fuel Injection Turbo Buggy Build
Water/Alcohol Injection
Audi TT intercooler
Upgraded to MS3Pro-Evo
EcuMaster PMU16
ECUMaster ADU5 Digital Dash
http://www.shoptalkforums.com/viewtopic.php?f=3&t=127936 |
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67rustavenger
Samba Member
Joined: February 24, 2015
Posts: 9749
Location: Oregon
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| Posted: Fri Jan 04, 2019 5:17 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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Well if it's that easy.
I could boost my DD 1679. With ease!
The problem I have is. No one makes an 1 3/8" header turbo setup for small displacement engines.
I want to boost. But do not want the turbo in the engine compartment.
Also I want to run heat exchangers. If I can clear those two hurdles. I'd be good to go.
| Krochus wrote: |
| oprn wrote: |
| busey wrote: |
| Krochus wrote: |
| What are your overall goals and what do you have on the car now for carburetion? |
Mild naturally aspirated 2.0L with a pair of 44 Webers is what i currently do have to work with. Turbo powering it seems like a great way to get more bang-for-your-buck for a weekend warrior, than an all-out high compression monster street motor purchase? |
Ya if you are set up with Webers already it makes little sense to start all over. Just keep the boost pressures low and very little needs to be changed. 4 -6 psi won't hardly even warrant timing changes, just fuel pump reference. There will be a kick in the rear that will put a big silly grin on your face too. |
No joke. When I went from a well tuned NA with my Weber carbs to 6psi boosted I didn’t even have to rejet or make any changes whatsoever to the carbs beyond adding pressure hats. |
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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| Back to top |
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oprn
Samba Member
Joined: November 13, 2016
Posts: 12678
Location: Western Canada
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| Posted: Fri Jan 04, 2019 5:35 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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| 67rustavenger wrote: |
Well if it's that easy.
I could boost my DD 1679. With ease!
The problem I have is. No one makes an 1 3/8" header turbo setup for small displacement engines.
I want to boost. But do not want the turbo in the engine compartment.
Also I want to run heat exchangers. If I can clear those two hurdles. I'd be good to go.
| Krochus wrote: |
| oprn wrote: |
| busey wrote: |
| Krochus wrote: |
| What are your overall goals and what do you have on the car now for carburetion? |
Mild naturally aspirated 2.0L with a pair of 44 Webers is what i currently do have to work with. Turbo powering it seems like a great way to get more bang-for-your-buck for a weekend warrior, than an all-out high compression monster street motor purchase? |
Ya if you are set up with Webers already it makes little sense to start all over. Just keep the boost pressures low and very little needs to be changed. 4 -6 psi won't hardly even warrant timing changes, just fuel pump reference. There will be a kick in the rear that will put a big silly grin on your face too. |
No joke. When I went from a well tuned NA with my Weber carbs to 6psi boosted I didn’t even have to rejet or make any changes whatsoever to the carbs beyond adding pressure hats. |
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It is that easy! If you can weld any header can be tweaked to fit a turbo and leave the heater boxes in place to boot. Equal length is not very important in a turbo header, for mild boost you will gain more by ignoring exhaust length tuning and just go shortest route.
The oil return line drainage from the turbo can be an issue if you mount it low. You might need a scavenge pump. |
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Krochus
Samba Member
Joined: January 01, 2017
Posts: 892
Location: NW Arkansas
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| Posted: Fri Jan 04, 2019 5:56 pm Post subject: Re: Blowthru vs/or Drawthru Turbo |
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If you have good sealing heat exchangers on the doughnut end and aren’t gonna try for “sloppy mechanics” boost levels you don’t even have to weld flanges on the exchangers.
With a turbo you forget everything you previously knew or understood about exhaust systems (within reason) with a turbo there’s only two considerations. Will it support the turbo adequately and can you bolt/weld the turbo to it. Primary size, equal tube length none of that stuff matters anymore.
_________________
1970 Turbo Baja Bug Turbaja 2165 t3/t4 Speeduino sequential EFI LS3 coil on plug ignition
1965 Chevy c30, Microsquirt turbo aluminum 5.3/nv4500 |
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