Goughary

So this happened today...



And since none of us need more than one...i may be able to renovate one and take yours as a core...if someone needs the basics done. Pm me if you have been following this and thought maybe you want a new aluminum throttle body but don't feel like doing the grunt work.

I have no timeline...so none of this is immediate. Just thinking out loud if it's helpful to anyone.

Spyerx

its hard enough keeping the E88 rings looking decent (raw aluminum).... i'm not much for cleaning my cars, i keep them tidy, but not very OCD.
Today was deep clean day on the 964 tho (wash clay polish wax, clean rings, interior). No wheels off underbody tho.

Goughary

Has anyone tried ceramic coatings to keep raw aluminum clean looking- on things like e88 rings...

Goughary

Here is a question for the conoscienti...

As i posted above, i went dumpster diving today and came up with a bunch of aluminum throttle bodies and some intake manifolds...anyone else has these laying around and don't want them?

Anyway...it's kind of fascinating me that i have a bunch of 964 aluminum throttle bodies, and they all have differences...most will be options...but a couple are clearly design changes to things that are bolted on. And i only have the latest parts catalog, so these things don't show in drawings.


That said...this is the oddball:







It has two resonance flaps. Which I've not seen before.

I did however find a couple of threads where these had been brought up before, but not one of those threads offered insight, info, or knowledge...

So- does anyone know anything about the history of the dual resonance flap? It has the same part number on the throttle body as the others. And clearly came earlier than the single flap unit. As there is a lever on the remaining resonance flap that always looked like it should attach to something- and i had been confused- but now i know it is a leftover from when the casting had the second flap, and there was an arm attached to it. Porsche simply changed the casting and took out the arm. And left the flap and vacuum actuator unchanged there on the right hand side of the throttle body.

Now- I'm assuming is was taken out due to the amount of vacuum necessary open both flaps- as it's much harder to open the tow than just one. So likely the second flap wasn't necessary or wasn't reliable enough.


Does anyone know the real story?

Spyerx

Goughary

The intake is from a 964 and has a 964 part number.

I found these pics on a thread from 2006 referencing a similar one coming off a 964...





I searched all the old parts catalogs i could find- no drawing of it references two flaps. I searched 930 and 993 and 944 and 968...but regardless it's a 964 part number...just don't see it anywhere.

If someone has a printed catalog from 1989, maybe it's in there? What about other countries?

Maybe the early cup cars or the RS?

Regardless - In all likelihood, they changed it either to save cost or because the vacuum wasn't enough to make it function properly...

Interesting though, that the part numbers on the casting btw the casting for two flaps and casting for one flap didn't change- though it's a significant change in the casting and design.

I'm wondering about the differences in total air volume from banks 1-3 to banks 4-6 though, as the dual flap allows the volume to be the same both sides - where the single flap means banks 1-3 have a significantly higher total air volume- and in the later plastic body, the resonance flap was moved to the center to correct this...

18T_BT

These dual flap throttles were popular and used in OEM applications in 924's and Audi 5cyl and even VW 16v. The idea was the primary, then the secondary open up, providing a non-linear throttle response and better driveability at low throttle opening. I am not sure how necessary that was on a larger displacement engine like the 3.6L.

Goughary

I think you are confusing the question.

I'm only talking about the resonance flaps...not the dual intake plenums...

There is normally only one resonance flap...but this throttle body has two....which seems to me to be an earlier design that was changed mid stream...

JasonAndreas

Maybe just the early MY89(?) and then the design was simplified and improved.




It was actually this reason or rather, problems with it that caused Porsche to stop using the dual-butterfly throttle and switch to a single-opening. The original was modified (MY91'ish) so that the large throttle plate would start opening after the smaller reached 5°, which helped. But there were still "problems during slow acceleration"

Goughary

That's what i was figuring - that they later simplified it for some reason. Now we have to find the guy that made that decision and ask him why...

cjoenck

Well, applying principles of aerodynamics, I would guess that two resonance flaps create more turbulence than one. Turbulence means loss off energy and less efficient flow. The more likely reason is that one flap is simply cheaper than two, one less part that could fail, and one less quality control point. Or it could be an entirely different reason altogether.

Goughary

Not much has happened here - outside of gathering more intakes and restoring 75 year old ball peen hammers...

But last night- i bit the bullet and while the wife and kid weren't looking....i disappeared into the basement, sanded the bottom side of the 356 Carrera badge, and mixed up some slow cure jb epoxy...

Then...









I held it down with tape, then as it set up, very carefully removed any squeeze out with a razor, and then a small screw driver and a tencel rag.

The good thing about not being singer...i don't have a customer that would kill me for microscopic flaws...bad thing about not being singer, i get these ideas in my head, and i can't hire some kid who is WAY better than me to do it for me. C'est la vie. Or at least - C'est ma vie...

cjoenck

Absolutely magnificent. Looks fantastic. Congratulations, this is a classic. Forget Singer

Goughary

Thanks...now back to sanding and shaping the other. And then ceramic and reassembly.

If any of you are coming to caffeine and carburetors in new Canaan Sunday, I'm bringing this manifold with me to show some people. Most of you are far and wide....but for the New York area peeps...

Santa Cruz Red

Now you'll have to design and build a clear engine lid to show off the excellent work!