<VV> Draw through Turbo's

[mmccrae6 at cox.net]

A Wynjammer Supercharger blowing through a 4.3 throttle body mounted on a four barrel manifold. I can send pictures and explain the development.
I'm at mmccrae6 at cox.net

-----Original Message-----
From: Hugo Miller <hugo at aruncoaches.co.uk> 
Sent: Sunday, March 22, 2020 9:45 PM
To: mmccrae6 at cox.net
Cc: virtualvairs at corvair.org
Subject: RE: <VV> Draw through Turbo's

That's interesting. That's another combination I have never seen - by the time fuel injection came in, the trend had switched from superchargers to turbochargers, presumably with the introduction of new seal materials that could withtand the higher temps. What kind of supercharger did you use and where did you put it? I was thinking of doing something similar myself.

On 2020-03-23 03:55, mmccrae6 at cox.net wrote:
> I have a supercharged fuel injected '66 Monza that works quite well, 
> thank you!
>
> -----Original Message-----
> From: VirtualVairs <virtualvairs-bounces at corvair.org> On Behalf Of 
> Hugo Miller via VirtualVairs
> Sent: Sunday, March 22, 2020 8:51 PM
> To: virtualvairs at corvair.org
> Subject: Re: <VV> Draw through Turbo's
>
> Yes, superchargers always suck (as far as I know!). The Spyder was the 
> first turbo I ever saw that sucked. In fact it's the only one I ever 
> saw, though I understand there are others out there, but not in the UK 
> I'm fairly certain.
>
> On 2020-03-23 02:49, FrankDuVal via VirtualVairs wrote:
>> My 1938 Supercharged Graham Model 97 (stock) draws through the Marvel 
>> Schebler carburetor.
>>
>> Frank DuVal
>>
>> On 3/22/2020 2:31 PM, kevin nash via VirtualVairs wrote:
>>>
>>>   Hugo- no the Spyder is not unique to use a draw through carburetor 
>>> set-up!! not even close! In the early days of turbocharging, it was 
>>> way more common to use a draw through arrangement on carbureted 
>>> turbo's... the Olds jetfire, the late 70's buick grand national(?) 
>>> numerous japanese makes in the early 80's also did it this way. One 
>>> of the quirks of this set-up is the compressor has to have a special 
>>> seal on it that will prevent lubricating oil from getting sucked 
>>> into the intake when the throttle is closed, and because this draw 
>>> through configuration used to be so common, Garret turbo's in 
>>> particular, can be had with this type of seal. The advantage of that 
>>> seal is that it is tough, can be used on anything blow through or 
>>> not, the disadvantage is that it has a bit more drag.
>>> Although draw throughs would "seem" to not be the best way to turbo 
>>> an engine, they do have some neat advantages... harder (nearly
>>> impossible) to send one into a surge, at least for the same 
>>> conditions this usually happens on a blow through. Draw throughs 
>>> tend to run cooler at part throttle/light loads than blow throughs 
>>> do.
>>> It
>>> is the easiest, simplest way to get a carb to work, as the carb is 
>>> always sensing vacuum. Theres no weird airflow changes being caused 
>>> by blade angle on draw throughs either... I've seen a couple of 
>>> youtube video's that test airflow variations to individual cylinders 
>>> at various blade angles, and it is pretty amazing as to how large 
>>> these variations can be. One test shows some cylinders down 50% on 
>>> airflow compared to another at part throttle, and basically no 
>>> variation at wide open throttle!! With blow throughs, if the 
>>> butterfly is big enough to never be a significant restriction at 
>>> wide open throttle and full boost, it is also big enough to cause 
>>> significan
>> t
>>>   drivability problems out of boost, but on a draw though, they can 
>>> be sized large enough to never be a restriction (if using EFI) and 
>>> not have any drivability issues at all.
>>> Carbed blow throughs tend to have massive flow losses even when the 
>>> carb is sized for the engine... one account that I read about, a guy 
>>> bothered to test the manifold pressure at full boost before and 
>>> after the carb... he was getting 28 psi before the carb, and 20psi 
>>> after!!
>>> Kevin Nash
>>> Draw through EFI daily driver, max boost tested=22psi
>>
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