What if...?

[StanJ]

During my time as a member of this forum, I’ve noticed several reoccurring themes; among them, a general appreciation for the appearance, heritage, and drivability of Weber carburetors. Quite often however, two other themes accompany this one – those of having to compromise either low or high RPM performance based on venturi sleeve I.D. due to traditional IR style manifolding for these carbs, and “packaging” issues in GT40-style applications that complicate inlet air filtering and further limit performance due to compromises in inlet runner length.

My questions to you all then, are these:

How important is the “traditional” IDA/IDF individual runner “look”?

Would a cross-runner, adjustable plenum (both volume and pairing) style manifold that utilized side-draft DCO/DCOE-style carbs be of interest to you? I realize that the basic cross-runner concept isn’t new, but we’ve developed some technology during the past year or so that greatly enhances the flexibility of these designs. Also, it seems to me that packaging and air filtration/supply issues might be simplified with this type of setup.

I realize that “how interested” is very often closely tied to “how much?”, but even that doesn’t matter if most of you picture this setup and think “Eeewww…” or “Sacrilege!!” If your gut reaction to the concept doesn’t include either of those, I’ll proceed a bit further with the idea...hopefully to the point of being able to give you some idea regarding price. At that point too, I’d like to have some input from the membership regarding application parameters – what deck height and what type of cylinder heads would you like to see such a manifold cast for?

 

[Howard Jones]

Whatever it is it must clear the hole in the engine cover without hacking it up.

 

[StanJ]

Whatever it is it must clear the hole in the engine cover without hacking it up.

Based on some quick, preliminary measurements of a local SBF-powered car, I think what I have in mind will fit without surgery, Howard. I'll reserve comment on the FE-powered stuff until I can measure one or get some hard data.

 

[Ron Earp]

Hey Stan,

I'll jump in here as a non-GT40 owner and throw out an opinion.

I think the Weber "look" is about 85% of why people go with the IDA/IDF, so, you can bet that this is extremely important to many folks. People are willing to give up performance, simplicity, and $$$ to have the look of the Webers.

 

[StanJ]

Thanks Ron; that's exactly the kind of objective opinion I'm looking for here. While I've always loved these cars, I freely admit to being a "newbie" with regard to whim and preferences of this particular market.

 

[Steve26]

I am currently running a 650 Speed Demon but only because of $$$$. There will come a day, I hope not to far out, when I'll go to the Weber's and I would only do it as per the original. This is has nothing to do with performance but rather one of the things that defines a GT40 like the gas caps, BRM wheels and crossover exhaust to name a few. I know my car will always be a replica and I would never try to pass it off as anything else but I would like it to look the part as far as I'm able. Just my .02

 

[Chris Martino]

Don't forget the sound of a Weber setup either!


Chris

 

[Jac Mac]

1.Why do it with DCOE or side draughts when you can do it with a series of passages in the valley of the current IDA manifold base's-particularly the FE.
2.Most of the current crop of Weber users can barely get their heads around the one throat per cylinder concept along with jetting and venturi size requirements for different applications & driving styles. The re-education process could be a bit daunting!
3.As soon as any linked plenums are involved the 'Weber' sound will be reduced somewhat.
4.Personally I am all for the idea & this would be something I would investigate if I had to prepare a car that 'had' to run IDA's, but as long as the 4bbls are around & winning I am happy.

 

[EGLITOM]

I will compromise on my car by putting on a 4bbl. I compromise on sound and look, but i gain on performance, drivability, maintainability and of course on costs.
So as i decided to compromise originality anyway, my question would be:
What is the advantage of the sidedraft weber concept versus a serious 4bbl setup in terms of performance, drivability, maintainability and of course on costs. If there wouldn´t be a significant added value, it wouldn´t be my choice.
I rather spend the money on one of your perfect 4bbls´s.))

TOM

 

[Dimi Terleckyj]

I love the traditional look of Webers but one major concern that has always worried me for street use is the amount of dust, sand etc the unfiltered inlets allow the engine to consume and cause premature engine wear.

On a street car the damage and wear is not worth the cost just to achieve a "look".

Personal observation and opinion only.

Dimi.

 

[StanJ]

Jac, I’m not familiar with the balance passage-style FE manifolds you mention, but I can’t envision a design utilizing conventionally-positioned IDF/IDA downdraft carbs which would not create a boatload of flow turbulence and pressure wave management issues, not to mention that the runner lengths would still likely be far too short for effective ram tuning at reasonable RPM levels. Not saying that someone else couldn’t have come up with a workable solution though, just because I haven't...

Tom, many of the performance advantages with the design I’m envisioning would come from eliminating the compromises in inlet manifold design that we V8 guys have been working around and band-aiding for decades. Inlet runners would be much straighter and the plenum design much more efficient, with the option to allow each cylinder access to 1, 2, or 4 carburetor venturi as desired (with the change from one configuration to another taking less than 10 minutes per side). The main advantage would be in runner lengths (and corresponding intake valve timing) that would finally allow efficient utilization of the much stronger “second order” pressure waves for ram tuning at RPM levels that make sense for street and occasional “track day” use. The inherent modular design of the Weber carburetor should facilitate fine tuning for the day’s intended usage. Based on recent test results from a system we designed and fabricated for a racing 4 cyl. Nissan, the potential power and torque gains (over current IR systems) should be impressive to say the least.

Dimi, mounting a dry K&N oval filter for each bank should be easy with this design; the filters themselves ending up over beside the engine compartment air scoops. Howard Jones’ comment earlier does bring up a valid point though, and I’ll need to put some additional thought toward a workable solution – how to quickly and easily disconnect the filters so that the engine cover can be raised.