Draw through vs Blow through 300 I6

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Draw through vs Blow through 300 I6

Ray Cecil
Been kicking around the idea of turbo charging. Two systems exist. I could go either way.

Does anyone here have experience with draw through? Im sure someone has experience with blow through, as that is more common.

I am just thinking out loud. Collecting thoughts. Considering options.

The truck needs to be reliable daily driver, but I am not opposed to doing something completely impractical and crazy, because crazy seems to make the hall monitors cry. I like making hall monitors mind's blow. That reminds me, I need to order that grenade shifter knob.
Ray Cecil
1982 Flareside 300 Six, Hedman Headers, 4x4, SROD 4 Speed, 1 Wire HEI "Little Blue 82"....
1969 Impala Custom Coupe, 86,000 miles, 327, Powerglide.
1999 Silverado, 346,000 miles, 5.3 Automatic Z71 4WD
2008 Tahoe (wife's)

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Re: Draw through vs Blow through 300 I6

85lebaront2
Ok, Ray, years ago Preston Carburetion was a distributor for Rotomaster turbo charger kits. Their system was a draw through using a carburetor. GM's first and second round of carbureted turbocharged system were draw through (first round Corvair Spyder and Oldsmobile Jetfire) FWIW, dad had a 1966 Corsa turbo and I had a 1963 Jetfire.

Advantages of draw through, carbureted:
(a) can use a basically stock carburetor
(b) Doesn't require higher pressure fuel pump
(c) crankcase ventilation hookup is very similar to stock
(d) distributor vacuum advance can be manifold connected to kill it under boost
(e) all vacuum operated components, power brake, HVAC and cruise work normally

Disadvantages of draw through, carbureted:
(a) carburetor has to be mounted and plumbed through the turbocharger limiting location flexibility.
(b) exhaust heat from turbocharger can be a problem.
(c) sudden closed throttle at high flow rates and engine rpm can suck oil past the compressor seal.

Advantages of blow through, carbureted:
(a) carburetor stays in stock location.
(b) turbocharger location is determined by space, exhaust and preference.
(c) no danger of sucking oil past the compressor seal.

Disadvantages of blow through, carbureted:
(a) needs a modified or special carburetor that is sealed, or a stock carburetor in a sealed enclosure.
(b) fuel pressure needs to be capable of increasing with boost
(c) vacuum operated components will need a good source like a mechanical or electric pump
(d) distributor vacuum advance can be used to retard timing under boost
(e) may need a blow-off valve to prevent compressor wheel damage when throttle is closed at high flow rates
(f) brass floats may collapse from boost pressure

If you go to some sort of injection, the manifold and fuel pressure regulator work best as a blow through system. Whatever you decide, distributor advance curves need to be changed, the higher inlet pressure and higher combustion chamber pressure result in a much faster burn rate.

As far as examples of blow through carbureted systems, many of the early supercharger systems were blow through, Ford F code 312 engines in 1957, Studebaker Golden Hawk and Avanti.

Most earlier systems were draw though Auburn, Cord, Duesenberg and the Blower Bentley and Mercedes-Benz SSK, also Alfa-Romeo.

If I can be of some assistance let me know.
Bill
"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 1994 Taurus LX
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413
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Re: Draw through vs Blow through 300 I6

Gary Lewis
Administrator
Wow, that's good info!  
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI
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Re: Draw through vs Blow through 300 I6

Ray Cecil
In reply to this post by 85lebaront2
Bill, thanks for that information. That took a few minutes to write out!

Every day I think of something else Id like to do to the 300.

Since the exhaust and intake are so close on the 300, I could see a really cool draw through setup.

Of course, this is just an idea, and I need to figure out the cfm and pressures etc, but wouldnt 3 teeny tiny little turbos all inline running off of 2 cylinders each, pulling air/fuel through three factory 1 barrels be so cool?

Call it the Turbo 300 3 Pack.

As far as exhaust heat, there is a pressure drop in a draw through system through the carb. Basically an orifice like in an air conditioner system. Draw through systems CAN have carb icing issues. This causes the intake charge to be much colder than a blow through system. This is why draw through systems dont use intercoolers. Combine this cool intake charge into the turbo, and a short intake run, or an insulated intake run, and I dont think heat from the turbo would be a huge issue.

Twin or triple turbos would be much more complicated to tune, being that multiple carbs are involved. However, not impossible to tune.

So, the questions are:
Blow through or suck through?
Single, Twin or Triple turbo?
What size turbo(s)?
what about a belt driven vortech style centrifigal supercharger?
And....how long before I grenade the SROD? haha

Ray Cecil
1982 Flareside 300 Six, Hedman Headers, 4x4, SROD 4 Speed, 1 Wire HEI "Little Blue 82"....
1969 Impala Custom Coupe, 86,000 miles, 327, Powerglide.
1999 Silverado, 346,000 miles, 5.3 Automatic Z71 4WD
2008 Tahoe (wife's)

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Re: Draw through vs Blow through 300 I6

FuzzFace2
Over on FTE there is a member running a turbo on a 300 six in a P/U.
I don't remember if it is in the 80-86 (think in here?) or the 73-79 area and has a lot of good information from what I remember.

Now you did not say anything about remote mounted turbo like under the bed?
Dave ----
81 F100 flare side 300 six/T18 project
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
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Re: Draw through vs Blow through 300 I6

Ray Cecil
Hmmmmm....with so much space under the hood, I cannot imagine the benefit of remote mounting. Although, that would be cool to see someone remote mount a turbo onto an exhaust stack, plumb back down through the bed to intake and have a BOV in the bed!!! HOW REDNECK WOULD THAT BE??? ID LOVE IT!!!
Ray Cecil
1982 Flareside 300 Six, Hedman Headers, 4x4, SROD 4 Speed, 1 Wire HEI "Little Blue 82"....
1969 Impala Custom Coupe, 86,000 miles, 327, Powerglide.
1999 Silverado, 346,000 miles, 5.3 Automatic Z71 4WD
2008 Tahoe (wife's)

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Re: Draw through vs Blow through 300 I6

85lebaront2
The one remote mount setup I saw on FTE was a 460 EFI engine. Mechanical superchargers are good, but still can benefit from an intercooler even on EFI systems. Multiple turbos can be a bear, look at the Ford diesels with dual turbos, a small one for fast response and a big one for higher rpm. Chrysler used two different manufacturers on their systems, Early turbo 1s had Garrett units, turbo 2 and 3 used Garretts along with turbo 4 (VNT), late turbo 1s including the 2.5L used Mitsubishi units (smaller for quicker spooling). The Neon SRT4, PT Cruiser turbo and others with the 2.0/2.4L DOHC engine used Mitsubishis.

If you decide to play with dual turbos, two of the Chrysler Garretts or Misubishis would be a good match, one for each group of 3 cyls (1 - 3 and 4 - 6) as it would (a) be even split on exhaust pulses (b) a natural hookup from EFI exhaust manifolds. The early Garretts are draw through and have the PCV system going through them.

My method of doing this with carburetors, two HD8 SU carbs, one on each turbo inlet with a small balance tube on the inlet sides for smooth low end running. A mechanically (pressure valve) controlled wastegate system, with both wastegates operated by a single control valve, fed through check valves from each of two 3 cyl intake manifolds. This prevents one half of the engine getting boost and the other half not. Gimmershmidt I believe that is correct, used half gas engines to build large portable air compressors, also some diesels. The 6 cyl ones used the front 3 on a 300 to run on and the rear three to pump with, so that might be a source for a split intake.

FWIW, turbos do best when mounted close to the source of heat and exhaust, they are an expansion "engine" and lost heat reduces power. The slick trick on the Corvairs and Jetfires was wrapping the exhaust piping into the turbo to keep the heat in (on the Jetfire it helped with battery life as the pipe from the right exhaust manifold went right past the battery tray).
Bill
"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 1994 Taurus LX
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413
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Re: Draw through vs Blow through 300 I6

Ray Cecil
Bill, I will have to digest what you wrote a little later. There are some componets you mentioned I am not familiar with yet. I will look them up soon.

I think I will start with enjoying the truck as is for awhile, and really dive deep into this turbo thing this winter.

My house near Gary still hasnt sold yet. Once it has, I will finish my garage. I just spent all day cleaning it out and getting ready to build the rebar and forms for the concrete.

Ray Cecil
1982 Flareside 300 Six, Hedman Headers, 4x4, SROD 4 Speed, 1 Wire HEI "Little Blue 82"....
1969 Impala Custom Coupe, 86,000 miles, 327, Powerglide.
1999 Silverado, 346,000 miles, 5.3 Automatic Z71 4WD
2008 Tahoe (wife's)

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Re: Draw through vs Blow through 300 I6

1986F150Six
This link is to a thread [with photos] discussing a draw-through system marketed by AK Miller back around 1980:

https://fordsix.com/viewtopic.php?t=74249
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Re: Draw through vs Blow through 300 I6

85lebaront2
Interesting, if anyone is interested I have a Roots type blower off a Thunderbird SC 3.8L and most of the intercooler plumbing and intercooler.
Bill
"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 1994 Taurus LX
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413
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Re: Draw through vs Blow through 300 I6

Ray Cecil
85lebaront2 wrote
Interesting, if anyone is interested I have a Roots type blower off a Thunderbird SC 3.8L and most of the intercooler plumbing and intercooler.
how much?
Ray Cecil
1982 Flareside 300 Six, Hedman Headers, 4x4, SROD 4 Speed, 1 Wire HEI "Little Blue 82"....
1969 Impala Custom Coupe, 86,000 miles, 327, Powerglide.
1999 Silverado, 346,000 miles, 5.3 Automatic Z71 4WD
2008 Tahoe (wife's)

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Re: Draw through vs Blow through 300 I6

85lebaront2
Probably figure $150 + shipping. Shipping may be an issue due to size and weight.
Bill
"Getting old is inevitable, growing up is optional"
Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator
Wife's 2011 Flex Limited
Daily Driver 1994 Taurus LX
Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413
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Re: Draw through vs Blow through 300 I6

Ray Cecil
You are in south or north carolina? I cant remember.
Ray Cecil
1982 Flareside 300 Six, Hedman Headers, 4x4, SROD 4 Speed, 1 Wire HEI "Little Blue 82"....
1969 Impala Custom Coupe, 86,000 miles, 327, Powerglide.
1999 Silverado, 346,000 miles, 5.3 Automatic Z71 4WD
2008 Tahoe (wife's)