Another solution would be to use an elliptical cam on the throttle cable. By having the radius of the cam vary inversely with the rate at which the flow area is changing, you could get a nearly linear response as measured "at the pedal".

 

Right, I have seen this as well. Would have done that, but issue is space. A teardrop would add 1.5" to the length of the slider overall dimensions.

Thought about that as well, easy enough to implement. Honestly I am not sold on the shape of the opening being the issue. For example, a butterfly has much worse cross sectional change of area in relation to pedal operation. My gut feeling is a issue with turbulence. On a butterfly throttle air is forced to make roughly a 45 degree angle change in direction while passing through. On a slider, its virtually a 90 degree angle for air entrance. We will see though, I have a few solutions if that is the case without a entire re-design.

 

I was talking to a friend of mine whose into motos about slide throttles. He told me a company designed a slide throttle with two vertical strakes in the opening to reduce turbulence at part throttle . . . Might be something worth looking into, especially if you could make the plates very thin.

 

^ ever since this thread I was thinking of something similar, but couldnt picture how to make it work with a round intake runner. If you guys dont mind a bit of shoddy MS paint, heres what I was thinking





This gives you the advantage of the no restriction of the throttle at 100%, yet smooth flow at all part throttle situations. Obviously it would be a bit more complicated to make, but not hard at all. But as I said, I cant think of how to make it work on anything but a square/rectangular intake runner. Unless you had a preformed piece of springsteel or something like that.

 

A bit confused how that is working. Is that a cross section view? Air would be coming in at the bottom?

 

Air would be entering from the top, youd have the slide throttle situated partially downstream in the intake runner. And yes, cross-sectional view.

 

The problem I see is the long pivot plate itself. When you slide it to the open position, the plate would have to get shorter so it doesn't jam. You have it operating like a door. It's arch is gonna be round on the opposite end of the pivot joint. You would need to radius the bottom section to match the travel angles. This wouldn't be that hard to do.

 

This is exactly what I'm planning with my 91 GTU. Still working out the kinks with a Semi P-port though.

 

sick build

 

Gordon. Just having glanced at his proposal I think what he is going for would be angled at say a 45 and pull up from the closed position. Think of it as roller barrel throttle body. But I could be mistaken as well. That's just my take on it. And speaking of roller barrel throttle bodies. Does anyone know where I can get a set of these built or bought at a reasonable price? I can't remember who but someone on the forum's built his own set and I'd be interested in these for my NA semi p-port 20B
On an STI
http://www.youtube.com/watch?v=ta6iJiKbfHg

 

I spoke with Logan a bit about the roller throttles last time I talked with him. I know he was experimenting with a design, but decided to ditch them in favor of the slide throttles. I cant remember his exact reasoning, maybe he can chime in.

 

Gordon I believe you are seeing it exactly the way I was thinking also, which is why I said I cant figure out a good way to make it work in three dimensions, which would be a spherical intake runner. You would need to have a piece of spring-steel or something that would be able to bend and form to the always changing radius of the intake runner through-out the slide throttles pull.

 

Simplicity might have something to do with it. I called my CNC guy today after I made that post, and he's working up something for me.

Gordon, I've seen roller barrels done with circular ports. But I know that Formula 1 uses rectangular ports. Would it matter on a street car ? I doubt it. But as for the runners, you could have them shaped however you need. So a transition from rectangular to round or some type of pyramid-ish shape should be possible. Kind of like a velocity stack.

 

Ok, I see what your getting at. It's a variable geometry intake runner. I don't see how you could make this though. The problem as I see it would be that you'd run out of runner diameter. It might be possible if you used a D-shaped port but even then the hinge would be a potential vacuum or boost leak.

 

Rxmfn7, It took me a damn long time time to figure out what you meant by "always changing radius". Hell, I even typed up a long detail reply only to realize it didn't really apply.

Anyhow, after giving it a lot of thought, I don't believe this would be practical or (more importantly) reliable enough to try on a car of any type. It might be doable enough for an engine dyno.

 

Yeah we had a full set made for Chris actually, but my issue was the weight and size of roller style. And what sealed the deal the most for me, was that with time any natural residue that builds up could easily jam it. Plus the transitional point of drivability is still the same as slide. So at that point, slide has all the advantages.

 

You wouldn't happen to still have them would you?? I'd imagine that while carbon build up could be an issue couldn't you just lengthen the runners to minimize it ; similar to top mount P-port ITB's or build in some sort of scraping edge??? As for weight Isn't there a way to machine the barrel's to decrease the overall mass? I really don't know. I've never CNC'd a set. But I do want a set on my build.

 

It seems that Logan keeps making new gains in HP with his ongoing R&D.

Sooo, I decided long ago that I was going to go all the way and do a slightly wider wide body for my car. The only front fenders I have an interest in are the Mariah Motorsports front wide fender. It is 1.25" wider per side and it keeps the basic lines that Mazda produced. It is also very high quality..

I pretty much can't stand any of the current stupid drifter looking garbage that I see done to second gens..puke.

I did always like the Tri-Point but that is gone and it was a bit to radical for this particular car.

So, I found a guy in St. Louis that I really resonate with. His name is Doug Jenkins and he is phenomenal.

http://www.dougjenkinsgarage.com/main/

This guy loves what he does and is super **** about his work and rep. I got him to go pick up the car from Logan and he has started.

We are using the Mariah fenders in front. I also bought a Shine Auto front air dam lip. I am having Doug file in the air vents along the bottom of the air dam. I guess they are for brake ducts or something. They look to me like they would just cause turbulence. I will also have the stock front lip available if I don't like the Shine piece or if I want a little higher front clearance.

For the rear we are doing the fenders in metal and we will make them about two inches wider. I hope to get a 305 under the fenders. I will be happy with a 295 though. I am doing a 17 front and an 18 rear wheel.

The rear fenders are to mimic the front in appearance. I want the car to look a little wider but not much different than stock. I think many people will not even know that anything has been changed.

Doug is also doing a super high quality original color paint job. The fender wells will be completely finished out as well.

So here we go. It was a little scary having someone hack up the car but I trust Doug.

The work is done in metal. There is a little filler used to cover up the wheel scratches but the work is in metal. The entire car will be taken down to the metal before paint.


























Doug should be done in about 1.5 months and the car will be going back to Logan's for the final engine work.

My car will be done this summer..... Right Logan??

 

^ Holy Sh*t that's nice work right there!


Logan needs to update his thread on those HP figures.

 

I think Logan's thread is up-to-date. I just meant instead of my car sitting waiting for Logan to finish intake stuff and testing on his engine that my car could be getting bodywork.

I want to pick my car up from Logan's this summer and it be totally finished other than dialing in the suspension.

 

I saw your car at Logan's shop last time I was up there. You have some ***** to let someone do that to such a clean GTUs Hope it turns out nice, your car deserves it.

 

 

nice work!

 

More pics from Doug. She's got some hips on her now!!

The vent shown is the cut out vent of the Shine Auto air dam. It is now smooth but I don't have any pictures yet. Next Doug will get the front fenders perfect then finish out the fender liners and then on to paint.

I think that it is turning out as perfect as I imagined.

The front fenders are 1.25" wider. The rear are 2" wider. I would like to get a 10" and 12" wheel to fit under the fender. That might be pushing it on the front. Maybe doing a 11.5" and a 9.5" will work. Or maybe a 12" and 9.5". Hell I don't know. I am getting custom wheels so the offset won't have to be a compromise.

I don't really know how the car will handle on the limit with a 2" stagger... much less a 2.5" stagger. I don't want this to be a understeer pig. Maybe I should just stuff as much tire under as I can and dial in the steering the best I can. I will replace any and all suspension components until it is right. Everything is just a starting point until it hits the road.

I plan on spending time at Hallett Motor Racing Circuit in north east Oklahoma with someone who can really help me set this car up. I won't have a hodge podge of parts that don't work together.

http://www.hallettracing.net/

 

I was a little disappointed to find out that in the tire size 305/30/18 there is not anything I have found available for the street. At least not on Tire Rack.

There is 295 and 315 for the street.

My front fender will be wider by 31.75 mm.

My rear fender will be wider by 50.8 mm. So it would just seem a 305 would be perfect. I think I would tend to go to a 295 before a 315 to limit the difference front to back.

I hope I can find a street tire available in this size.


Any suggestions??