Happy Thanksgiving everyone....so I have seen this before but have never heard about the results.....is the idea any good? How do we get it done on our cars? Just thinking out loud....thank you
gg

Check with High Performance House in Redwood City.

I'd be interested in learning more, now that I have the Microsquirt to tune for it.

Look on the Samba for a 2.1L Vanagon throttle body. They are 50mm vs 45. You have to modify the throttle shaft on your existing throttle body to fit the larger throttle plate in order to keep the TPS. I enlarged the plenum to 50 mm with a tail pipe expander and ordered a new gasket for a Vanagon. My engine is a 2056 using 1.8L plenum, runners, and Let fuel injection.

The horn on the air box will flow how much? They look pretty small.

did it long ago 0n my D-jet 2.0 euro 4 with webcam73 - made midrange boost you could really feel - iirc it was a 4mm overbore

back then it was being done by Ed Mazula in SoCal - i've archived all my 914 documents; i think you can find an old post by me with the info

Careful. HPH is rather expensive IIRC.

I've seen this mentioned in threads before, primarily for the 1.8L plenum. Does anyone know of a good thread demonstrating how to do this on a 2.0? I'd love to open up air flow a bit for my 2270, not just for WOT but for getting more air at cold starts.

RC Fuel Injection in Torrance , California.
They enlarged our 2L t/b, and installed a larger dia butterfly with new shaft o-rings.
Fair pricing as well.

I did cut back the air horn and used a 55mm motorcycle velocity stack on eBay for $12.

Now we're talking

@BeatNavy Rob, I tend to find more information on Shoptalkforums on this topic.

Here's a thread looking at plenum efficiency and Vanagon TB. Seems appropriate for your 2270. But do some search there as there is a lot more information. Pyledriver seems pretty knowledgeable.

https://shoptalkforums.com/viewtopic.php?t=102542

Definitely following closely all of your engine work/optimization.

I can offer one data point that may be useful...in reviewing the Microsquirt datalogs for my car, when I rev it up at full throttle I rarely see below 96-97kPa...my GM MAP sensor is mounted on the plenum and has a hose going into one of the big hose fittings in the plenum itself. This implies to me that the throttle body is not really that much of a restriction. Stock 1974 2L D-jet plenum, runner, and throttle body, 2056 with mild street cam.

Rob, I'd be interested in what your data logs show for a full throttle, full-RPM run.

Thanks Montreal914 ! That's a very interesting thread, although wow do they go into 8 pages of theoretical. What my smallish brain took from Jake and everyone else's postings: plenum turbulence is bad and at some point smoother air is at least as important if not more than simply MORE air. Not sure what to do with that, tho? Try a bus plenum?

FYI, I did reach out to RC Fuel Injection about cost / recommendation for boring out a 2.0 TB. Looks like the base cost for "most Porsches" is $289. Not sure what that includes, but I'll pass info along. Given that it was late Friday afternoon, I don't expect a response for a few days. Thanks for the tip, Maltese Falcon .


Greg, good idea. I follow your logic. I don't know enough to know if it's valid or not, but I do get the logic, and I'll try to post something soon. I actually haven't done a real run since I put the BMW IAC on it last week and played with the tune, but at WOT nothing should have changed. With Thanksgiving house guests and the colder temps (and heat not currently hooked up on my car) I haven't had a chance to really run it.

EDIT: User tagging not working up in the body of my response for some reason

@Montreal914 @Maltese Falcon

At this price point on the TB modification, I would seriously consider this one from GoWesty. I definitely like the sealed ball bearing for the throttle shaft. There might be a TPS/lever orientation issue ( I have read somewhere) but someone had gone around this problem. I think I had read it on STF. Obviously, this would mount on a Vanagon plenum which might be better for the 2270(?)

https://www.gowesty.com/product/electrical/...e-valve-housing

Click to view attachment

$300 for a new TB ain't hateful. But you'd need to see if the TPS is swappable, as this is a single-mciroswitch Digifant setup.

They offer a "Gowesty Fuel Injection Component Replacement Kit" that uses a "All-new Billet Aluminum Throttle Body with modern TPS" so I'm guessing it could be converted...?

https://www.gowesty.com/product/electrical/...ement-system?v=

I believe @JamesM is running the Vanagon TB and plenum. I'd be interested in what's required to make that work. I can't find a good pic of one of those plenums, as I'd like to see what the vacuum outlet/port selection is like.

I think this is is rig. Very clean setup. But I can already see I'd probably have wiring harness issues with the way it's oriented.

Throttle body is 2.1 vanagon, the plenum and runners though are 74 1.8 parts. Only modification made was using a tailpipe expander to open up the plenum to match the 50mm vanagon TB, and swapping the throttle arm from a 1.8 throttle body over to the vanagon throttle body for proper throttle cable orientation.

Using the Vanagon plenum is a bit more complicated as no 914 intake runners are a direct match to it.

I have one of these on the bench waiting to be installed this winter as my motor is needing even more air than the 50mm vanagon TB can provide. The throttle arm is in the wrong orientation and needs to be swapped and due to the design of the TB itself it is not as straight forward a swap as using a stock 2.1 vanagon TB. The GoWesty unit however is 52mm and uses a flat throttle plate as opposed to the 2.1 vanagons tapered thottle plate that creates some restriction at WOT.

Its a really nice piece, out of the box its actuation is buttery smooth.

I think Mr Kona had a thread on this, well done.

Chris, I have the enlarged throttle body on my car that you did years ago, it definitely made a difference on the 2056

And this is on a 2056? What kind of cam/head setup?
Thanks!

yeah on a 2056, I dont have the specifics as I didnt build it but its far from stock. AMC 1.8 heads with oversized SS valves, port work, and custom chambers by EMW. EMW cam of some sort. Motor really come alive 3700+ rpm

Going to be swapping it again for the 52mm throttle body over the winter is its still wanting more air.

Andy's TB?

I had a thread with a blow by blow write up on changing the TB to the GO-Westy unit.

On my 2056 the tuning showed it made a difference.

If you do this one of the things you HAVE to do is enlarge the horn on the plenum. Its thin metal and easy to do with an exhaust expander.

Zach

http://www.914world.com/bbs2/index.php?act...=2&t=353039

Here is my thread on moving from the stock TB to the GO-Westy unit.
It shows all the steps needed to convert the unit (its EASY!)

It also has my home built smoke tester for testing the intake.

Bear in mind when I did this I id it for my Microsquirt 2056. So my TPS is a little different then the L-Jet unit that started on the 1.8, and may be a tad different then the TPS you use on your machine (but probably not, and its still super simple to make the bracket.)

Zach

That was a good write up, and a clever idea on addressing the horn. Did it come out looking pretty stock?

There is not a lot in my engine bay that looks stock, aside from the 1.8 airbox/plenum/intake runners. Once you get past that, its ALL modified.

That said, the TB is pretty buried on a 914, so you never see it either way unless you go spelunking to find it. And being black it hides even more.


Zach

So now I'm wondering out loud how well that would work on a 2L plenum...

Maybe with an adaptor plate between the plenum and the TB? Just going by visual memory here...

Late to the conversation. But I remember talking about different plenums and ran an idea that got Jake's approval back in the day, swapping an older version. It's all talk until we see what works.

Bigger isn't always better. If you can't measure the flow and the related combustion, it's all guesswork. Bigger inlet doesn't necessarily mean more air flow where it's needed. In fact smaller can be more effective. Too many factors.

Sigh. Watching to see where it goes.

Concur.

But with my Microsquirt setup, I can infer changes in airflow by swapping TBs, keeping the target AFR tables the same, and seeing what the fuel (VE) does. Significant changes in fueling, either way, imply significant changes in airflow.

First step is committing to spending $300 on a TB and then (likely un-return-ably) modifying my plenum with the hopes and dreams it'll matter. Can't see that happening soon.

@gregamy
@vaccarabite

i posted on the other thread but was wondering the same thing.