Blow Through Carb

[Gregors]

Is there a blow through carb that will fit on the 1800 engine? Would a special intake need to be machined? Curious about putting forced air into the carb'd engine...

[wmausbach]

Forget it. Tuning is almost imposible. There is a reason there have never been a good street blow through. If the professionals have not done it then a DIY wrench turner does'nt stand a chance.
Ciao
Wayne

[Daniel]

Never seen one on a Fiat but have seen a setup on a toyota it was temperametal also there was a shop that experimented
with this as well and told me the carb would heat up to the point they had vapor issues if you were to use FI it should
work fine but costly !

[Gregors]

I see, interesting though. I understand the webers are pretty good for using low amounts of boost more or less as they are.

[BEEK]

mazarati biturbo, the early ones were blow thru carbed, i belive if memory serves me correctly

[wmausbach]

Yup The BiTurbo Maserati was one of the worst cars made. Why don't you try the suck through which is the way Lampredi did it. Also I have had several discussions with Tom Bruch on this aspect of turbo design. He has always used the suck through approach and his Bonniville records prove it. All of his records were set using a Weber with a suck through turbo.
http://www.hotrodhotline.com/feature/he ... t_Only.pdf
Ciao
Wayne

[BEEK]

i wasnt making a specticle of the car, just the blow thru carb ... personaly efi is the only way to go with a turbo IMHO

[wmausbach]

Again I'll quote Tom"while the others are fiddling with their computers, I'm setting records".

[Daniel]

I've never played with this but my understanding is the engine is more driveable using blow thru design but
the carb becomes the issue as it was never designed for this . For a race engine i agree with you wmausbach,
would make the most sense to use a draw thru type !

[wmausbach]

Well, the suck thru design is so simple because the carb does not know the size of the engine. The carb is tuned just like a normal car, the turbo/ Spercharger acts as a multiplier. I am building a Volumex replica using a Volumex from a Lancia. The Lampredi design is simple and still gives a good HP for a street engine. According to Guy bolting on a 45 mm DCOE is good for 160hp even at the standard low boost pressure.
Ciao
Wayne

[Daniel]

sounds like a fun project where did you get your hands on a volumex supercharger ? are you here in the
States, Canada or on the other side of the pond ? whats the normal boost for a volumex anyways .


Daniel

[wmausbach]

I'm in Houston, Texas. We are very forumate to have a lot of Fiatisti here. I bought my Volumex from Stan, one of our local guys who is had several. He started on his replica 037 and bought a R10 Volumertrico (1500cc vs 1100 cc Volumex).
I bought his extra Volumex. Like I said it came from a Lancia Beta with the crossways engine. I had to get brackets to put it in the spider. I still have to fabricate a intake manifold to fit the 45 mm DCOE I have.
Stan had another one built by Shadetree Engineering that dynoed at 190 hp and he so;d it to Jerry Lee of Vick's fame. Ot had a lot of modifications including a different pully running 8psi. The standard Volumex is 6.5 psi and is a mild state of tune. The 135 hp is with milder cams than the stock 124 Spider. Guy Croft states that just adding the 45 DCoe adds 25hp.

That's what I wanted a good strong street engine that I did not have to rev to 8000 rpm. Along the way I also picked up a Toyoda MR2 supercharger for a good price ($100). It has a elrctomagnetic clutch but that require more eloborate set=up. It is about the sae size as the R30 Volumex (1100cc).

Ciao
Wayne

[Gregors]

Forget it. Tuning is almost imposible. There is a reason there have never been a good street blow through. If the professionals have not done it then a DIY wrench turner does'nt stand a chance.
Ciao
Wayne

Sounds like there are some interesting options, in fact. I like the suck through idea. And there have been many blow through carbs that have done fine, I'm not sure what you are talking about. Anyways, this is the performance section...

[wmausbach]

The point is that there have NOT been "Many" blow thru bit there have been "Many" suck thru such as the pre-War MG's to the Abarth Volumex. There are sound engineering reasons why this is so.

I guess I am a big fan of Lampredi's simple yet effective design of the 124 Volumex.

Ciao
Wayne

[Zmatt]

In maximum boost the argument is made for blow through. Personally I think forced induction is efi realm. It seems the engines just don't want to cooperate and you have to retune a lot to make it work, not to mention that with efi you can make more power for the same effort.