Slide Throttle / High Butterflys....

[Tspringer]

I've been kicking the idea around of building from scratch a "ultimate hotrod" engine for my '69 911S. Im thinking this coming winter to make this a project, and perhaps begin getting the parts together and all machining work done this summer.

Right now Im going to be doing interior (its on a diet), suspension, exhaust and other upgrades with the "R Gruppe" attitude and track use in mind. The car has a sweet running 2.7RS MFI engine in it now.... (except it pukes gas into the oil until I figure out how to fix it) but more power is always a good thing.

Im thinking a 2.8 twin plug shooting for around 275hp would be just tons of fun. I know I want MFI too, so I want to choose a configuration for which space cams exist so the MFI will run properly.

I currently have a spare complete MFI system, a 2.4 "T" core engine and lots of other bits and pieces to start from.

I would LOVE to have a slide throttle injection system. They are SOOOOOOOOOOOO cool.... but I called Andial and they quoted $7,600.00 for the slides and linkage alone. Uhhhhhh not that cool I think.

Anyone know of other sources? Anyone have the blueprint specs for this stuff? Any chance a good machine shop could build it from scratch for less? Any alternatives?

how about a high butterfly setup with tall stacks? Advantages? Sources or costs?

Am I insane?

Terry

[GeorgeK]

Slides are way cool...until they stay stuck in the wide open position. It seems every slide will do that at least once; after it happens, the car is toast anyways, so the slides have time to unstick themselves during the rebuild.
Go with butterflies. Cheaper, more reliable, and not such a loss in performance.
GeorgeK

[TimT]

Either method you choose make sure to bring wads of cash!

Try

these guys for another source of slide throttles

[David]

I've made a slide valve system for a three rotor Mazda engine. If you're serious about making one let me know and I'll give what help I can. One tip I'll give you if your going to design your own, you've got to have the slide plate running on bearings. Also, the one I made had round holes in the slide. This works fine but I've heard a 'D' shaped hole gives more linear throttle response. I don't have a pic of the one I made but here's a pic of the car. It's a '58 Austin Healey Sprite, 1550 lbs with about 425 hp.

[Paul Thomas]

When i was re-doing the stacks on my motor (3.5 MFI) i considered both the choices that you are. High butterflies that need a rebuild will probably still run $4000. I was told that by Matt blast at Eurometrix, who rebuilt my throttle bodies to my specs. Anyway, i ended up boring out a set of '69 S magnesium stacks and using 49mm Carrera 6 velocity stacks. It still looks stock until you look down the bore.

For space cam work you should call Hanz at H&R in New York. If you give him the info on your motor, he will custom build a pump for you. He even has core pumps that he already knows are good. 631.589.1600

Paul

[Adam]

While you're at it, try Injection Perfection. They're an Australian outfit that can custom make them for you. With the exchange rate the way it is right now (US$1.00 = AUD$1.85), it's a bargain!

I think it's www.injectionperfection.com.au

No affliliation, just word of mouth...