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Hi JRP,
I have experience with Weber Carburetors 48 IDA 's on small block Chevy V8. The race car braking system required a vacuum booster for proper brake bias (vintage Formula 1 braking system in late 1960's.
The first design of the vacuum system was similar to yours
The discovery was the tubing id was too large so each cylinder could "cross-talk" with another affecting throttle response.
Inglese Induction (now Jim Inglese) had in 2002 a vacuum system with miniature copper tubing and fittings, a common connection block with an outlet larger diameter for the vacuum hose to the booster tank. The restricted miniature id prevented cylinder "cross-talk" but provided sufficient diameter to replenish the vacuum on each brake application. Might need a booster tank in series with brake vacuum cylinder for your application.
Can contact Jim at https://jiminglese.com/
Tom
@T&T Racing Thanks for the info. For the design shown above, I was basically using the design from the BMW S54 engine to collect into the common vacuum rail and then a fitting on either end of the rail would be plumbed to the brake booster and the IAC valve.
For the new design, I have cylinders 1-2 and 3-4 plumbed in parallel and then plumbed into a small collector between cylinders 2 and 3. I can (hopefully) use this collector to supply the vacuum for the brake booster as well as the vacuum signal for the fuel pressure regulator and even a map sensor. You can see the plumbing a little better in these images below.
Any plans to make an open trumpet/plenum-less model?
Perhaps down the line. That would honestly be easier than the configuration with the plenum, but I'm determined to initially make the plenum variant for better street drivability.
Hi JRP,
I have experience with Weber Carburetors 48 IDA 's on small block Chevy V8.
Ha, years ago I ran a set of Weber 48 IDAs on my modified 1965 356 C. The throttle response was immediate. I also ran two Weber DCOEs in a "4-barrel" configuration with an Inglese manifold adapter on my highly modified 1976 Capri II V-6. I no longer have the Capri, but I still have the Inglese manifold and carbs. Once again, this car had a lightning-quick throttle response. So yeah, ITBs would be cool.
An interesting project. What is the plan for manufacturing the parts? Is this lost pla with casting, laser sintering aluminum, or something else?
The inlet manifold and plenum are made of machined and welded components, then bead blasted for a more consistent and textured look similar to a casting.
I'd love to have some investment cast parts made, but not sure I can get the cost low enough even with overseas parts. I do intend to investigate this option a bit further though.
The throttle bodies, linkages, throttle shafts, butterflies, etc. are all machined components, mostly 6061-T6 aluminum.
The flow differences between horizontal and vertical butterfly shafts could be significant, especially at part throttle. Are you aware of anyone running vertical shaft ITBs with a similar type of runner system? The BMW system you showed has horizontal shafts, and intuitively to me, that seems like the one that would yield the more uniform flow distribution.
The flow differences between horizontal and vertical butterfly shafts could be significant, especially at part throttle. Are you aware of anyone running vertical shaft ITBs with a similar type of runner system? The BMW system you showed has horizontal shafts, and intuitively to me, that seems like the one that would yield the more uniform flow distribution.
@Tom Pultz Perhaps at some point I'll do a basic CFD on the horizontal shafts versus the vertical just to see what the flow path looks like. I don't think it will have a noticeable effect on an engine that's not a pure race engine built to the max though.
As far as other engines running the vertical shaft throttles, this one comes to mind:
I also came across this 8v engine a while ago. I know it's not apples to apples since it's running open trumpets, but still - vertical shafts on a 8v engine.
Thanks for the comments guys! I enjoy the discussion.
In one of the pics, there is a series of blue fittings with braided line running to each of the fittings. Is this an extra oil line? I don’t see any feed line going to it. Looks like a custom setup. TIA😀
In one of the pics, there is a series of blue fittings with braided line running to each of the fittings. Is this an extra oil line? I don’t see any feed line going to it. Looks like a custom setup. TIA😀
In one of the pics, there is a series of blue fittings with braided line running to each of the fittings. Is this an extra oil line? I don’t see any feed line going to it. Looks like a custom setup. TIA😀
those had solid lifters so I imagine it’s some supplementary oil jets to the valve train
Bump for a very cool thread.
My research showed up with some examples of people struggling with ITBs for idling and drivability (although, none of the examples I saw were Porsche).
Would you say they are best used for race car and not DD or is that untrue?
JRP944, I am really watching your progress... I might be a future customer.
06-30-2023, 03:48 PM
