Beery's Twin Slide throttles

[beerhead]

After 3 years of R&D (reading and drinking) I've finally decided to try and make my 50mm taper throttle bodies!

Keen to hear what people think of my design. This set is a little rough because they're hand crafted, but if they work ok, I'll get a batch laser cut, in DCOE configuration to make it easy to adapt onto any car.

My theory behind using a taper is to have the throttles work like a variable choke and maintain better port velocity throughout the whole rev range, so more torque and of course like all slides - WOT is nonrestrictive.

Tomorrow's job is to make the cam style actuators for each end of the slide that will give me really precise control of the throttle at 0 - 20%, and faster throw after that.

The images of the slide open here is a mock up of what it'll look like, fingers crossed my actuator design works well






Cheers!

[ToyTA22]

Good thinking with tapering runners, as said helps with keeping velocity. The taper I used on a 1.7l Ford crossflow, I know don't throw rocks at me, was 3.5 to 4 degrees with good success. I used a techalmit mechanical, very antique, injection setup.
I used a sliding plate which was a bit touchy down low but great in mid range and up. So your cam idea would be a much better idea.
I don't have photos anymore, my ex wife destroyed every thing from my motorsporting past, otherwise I would post them for comparison/ ideas.

[oldeskewltoy]

have you looked into barrel throttles??

barrel throttles are superb @ WOT, but have other issues @ throttle angles other then WOT.




Cosworth - http://www.cosworthusa.com/sto...t=346

Hasselgren - http://hasselgren.com/billet-b...alve/

Titan(Uk) - http://www.titan.uk.net/produc...rrels


The 260+hp 4AGE I saw @ Loynings last year was using barrel throttles

[beerhead]

260HP 4AGE is pretty amazing. I had a look into barrels, but on a street motor the low rpm turbulence will ruin port speed and bottom end drive-ability. The downer with the twin slide is the complex actuators, but fingers crossed I've got that sorted.

ToyTA22 - is the setup your talking about like the mech injection on a 2002 BMW?

[ToyTA22]

Hi beerhead - The Techalmit injection system was primative in respect of being constant spray design i.e low pressure electric feed pump, engine driven pump then two mechanical regulators and a variable orifice fuel control valve before the injectors. Like a better design of Hilburn injection.

[beerhead]

Bah! My motor sits too far back! (75mm behind any 3S KE70 I've ever seen 100mm behind an AE71 4AGE). The first design of the actuator was no good and fowled the firewall! After looking at how a 20V linkage works this afternoon I think I've come up with a solution that will save 50mm of space at the rear of the throttles, and make life easier making the unit fully sealed. I've designed a simple bypass system that uses a bolt and a locking nut to adjust flow individually from a vacuum rail to feed the rear of the throttles too.

[Billzilla]

I'd just stick with unglamorous butterfly-type throttles.
They won't stick at the wrong time (which will be when they're fully open) and are much easier to make. And if done properly they hardly make any more restriction than barrel or slide throttles.

[beerhead]

I've got 42mm butterfly's atm, but with 14:1 comp, E85 and 300 duration 12mm lift cams I think I need a better way to make the motor breath. These are being tigged directly to a heavily modified 5SFE head giving enhanced valve / port angle. I'm building a poor mans dry sump with a 2nd hand external 3 stage for scavenge 2 to the sump 1 to the head to help the above. Will use a 5SFE oil pump for high pressure. Problem with a motor like this will be if I go 50 or 52mm butterfly's I'll have zero bottom end port speed. I'm hoping with these slides I can pick up mid range that a motor like this normally lacks.

[Billzilla]

You don't need 50mm or 52mm butterflys to make up the difference in airflow over a 42mm set. Since you're keen to do some machining what I'd do is make up a set of flat butterflys, ones that have the shaft and butterfly as a single piece of metal. You'd have to machine it down from a larger, thicker chunk of metal (and maybe just weld the shafts on either side) but it would let you get a completely flat butterfly that doesn't have a shaft sitting in the middle of the throat. You'd only need maybe a 44mm diameter one for that.
The other tricky part to that is you need to make the throttle body in two pieces to assemble it.

[oldcorollas]

regardless of what throttles are there, you will have crap port speed at low revs with a 300deg cam.
the slides will not change the fact that you have a large port relative to the volume of air goign through.

other problems.. how will you seal the slides, so air doesn7t get sucked aroudn them (and end up having a 3Krpm idle speed)?

btw, there is a twin roller throttle that does what you are trying to achieve.. with counter-rotating throttles

this one..
http://motorsport.bdg.com.au/roller.html

[Ben Wilson]

The only set of slide throttles I've ever looked at was a scary thing from an engineering perspective. Lots of little cylindrical roller bearings to stop them sticking and these scarily thin paper gaskets to keep all the clearances right. They were an old school single plate slide throttle, I'm having trouble seeing how you plan to seal the whole lot to stop them leaking as well.

[beerhead]

Thanks for the support

I'm not to be too deterred at this point. I picked up most of the parts I'm using to attempt these slides for $40. I own an AC tig to finish the manifold too Slides will be ball race, 4 fixed bearing at one end of the slide and a floating spring tensioned set at the other, all thanks to a stack of broken hard drives I butchered for parts. 2 ball race actuators per slide at each end that are counter apposed will remove any element of rotation under throttle actuation. Don't go of these starting pics too much, they're just to demonstrate how the slides will move. Once I shorten the slides and braze the pushrods on you'll even believe this has a chance of sealing.

[beerhead]

Oldcorolla's - You realise these are $2000 for a single throttle?

Not really a comparison of the DIY approach I'm going on. BTW All the leakage that will exist in the slide will link back to the idle control port (top end above the slide on each slide). By having an adjustable venturi from each port that links to vaccuum rail to the idle control solenoid I'll be able able to balance out each port too.