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Individual Throttle Body tech


EURON8

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I've managed to get my hands on both sets of ITB's

hey you recon you can take a picture of the backtop throttle, if not too much trouble? the face that bolts to the manifold. and measure height and width? they dont have a round exit like silvertop from what ive heard. want to compare to smallport 4age port size

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I've managed to get my hands on both sets of ITB's

hey you recon you can take a picture of the backtop throttle, if not too much trouble? the face that bolts to the manifold. and measure height and width? they dont have a round exit like silvertop from what ive heard. want to compare to smallport 4age port size

The silvertop throttle inner face isn't round either, it's almost like 2 circles offset by a mm or so. I was expecting something similar from the blacktop ones when you said they weren't round. I was actually a bit gutted to see just how not round they are.

SANY2746.jpg

I just took a photo of the gasket because its easier to photograph. Throttle body is obviously the same. I can grab some measurements for you, just tell me exactly what you need.

That shape makes making a manifold a little bit more difficult. I'm almost considering filling them in with resin or something because the size of the throttle on the head side is actually bigger than the butterfly, which can't be good for flow.

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hmm yeh, is an odd shape alright. i was hoping they were tapering down to an oval shape much like the exit of the manifold. looks like i will stick with the silver top throttles. cheers for the pic anyway.

wonder if its possible to use the throttle plate out of the backtop throttles, in the silvertop throttles. having them machined with a nice taper all the way through. but alot of messing around, for not alot probably.

could machine the exit round, and put an insert in the blacktop throttles to do the same i guess

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hmm yeh, is an odd shape alright. i was hoping they were tapering down to an oval shape much like the exit of the manifold. looks like i will stick with the silver top throttles. cheers for the pic anyway.
I would probably lean towards silvertop throttles just for ease of manifold fabrication and the fact that they would probably help keep the air velocity up, especially if you're talking 1600cc capacity. I'm trying to put together a higher output 2 litre engine, so the extra few mm of the blacktop throttles is probably worth the extra pissing around.
wonder if its possible to use the throttle plate out of the backtop throttles, in the silvertop throttles. having them machined with a nice taper all the way through. but alot of messing around, for not alot probably

Possibly, although I think people can sometimes spend a lot of time and effort attempting to make something work that can easily be bought off the shelf for not a lot of money. Bike ITB's are another cheap option, but even brand new Jenvey throttles can be picked up for quite a good price.

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what about getting 4 throttles off 1300cc nana corrolas or somesuch thing and then coupling the shafts up? I guess the housings wont be as compact but if you are making the manifold this could be accomodated. I think the falcon throttle I got was something like $28 as pick a part. if only they would give you a bulk discount 4 for $50 or something like that could make it worthwhile for ultimate cheapass quad throttles.

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My silver top quads are perfectly round both ends? Would quads be a waste of time on a slow reving motor? I was under the impression you dont gain piss all power, just makes the motor more responsive?

They aren't round. I only noticed it when we were modeling a pattern for the intake manifold flanges and round holes didn't work. Like I say though, its only ever so slightly not round, like 2 circles of the same diameter with the circle centre offset by 1mm or so. I’ll try to grab a picture of my sapre silvertop throttle if I can track it down.

For me the advantage of using quad throttles is purely in manifold design. I pulled my intake manifold off last night and it is absolutely horrible, like pretty much nothing Japanese I can think of, although there are some nasty intakes around. It has long runners though, so would be good for torque and mid range. Apparently changing this manifold for a more efficient design, along with a better exhaust at the other side, brings these engines (C20XE) up to 180bhp from 150bhp, so quite an effective gain before you even start internally.

Tom, linking up random throttles would be quite a lot of mucking around. It could be done and it probably wouldn’t be too tricky, but I don’t think I would bother. The best thing about either set of 20 valve throttles is that everything is included in the package, yet you can add more or separate them if required. They have all the linkages, the tps and even the attachment for the throttle cable, so making the manifold with bosses for the injectors/fuel rail is the only thing you have to do.

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Tom, linking up random throttles would be quite a lot of mucking around. It could be done and it probably wouldn’t be too tricky, but I don’t think I would bother. The best thing about either set of 20 valve throttles is that everything is included in the package, yet you can add more or separate them if required. They have all the linkages, the tps and even the attachment for the throttle cable, so making the manifold with bosses for the injectors/fuel rail is the only thing you have to do.

Yea and they are very bulky you would end up with a monstrosity. I brought in CBR600 throttles (1000cc are the same price and are around ~43mm) for under $100 and they come with outboard injection standard and injectors built in the throttles. They are one unit so your spacing would have to be similar to theres to get a sweet intake mainfold

As brad has said about the benefits of throttles, Biggest gains are usually from replacing a inefficient factory manifold. Second is its easy to Helmholtz tune your intake once you have throttles, then better throttle response. Also makes it easy to run things like outboard injection.

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will also help idle with big cams. over a single throttle setup, especially if has a large plenum.

was looking into the blacktop throttles. as 4age smallport ports are the same size or maybe slightly bigger than silvertop throttles. so blacktop throttles would get me a better entry. but sounds like alot of work for a small, if any gain. at the moment i run a tapered manifold and it steps down to the port.

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They aren't round. I only noticed it when we were modeling a pattern for the intake manifold flanges and round holes didn't work. Like I say though, its only ever so slightly not round, like 2 circles of the same diameter with the circle centre offset by 1mm or so. I’ll try to grab a picture of my sapre silvertop throttle if I can track it down.

That's weird... I'm sure mine were perfectly round. We found used a 43mm drill bit and didn't even need to port match the flange.

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Yeah, the facelift Silvertop engines go a lot better because the manifold is nicer, so it would make sense if the throttles were slightly different.

Brendan from Garage Dori/Niteparts told me that the silvertop throttles are better when I was starting the Beams conversion because they are a better shape:

I would def use silvertop 42mm throttles, these will flow 280ish hp with standard throttle shafts- so no restriction there really. Much better shape than blacktop with the kidney backs that stall flow.

.....

Standard cams & adj cam wheels are a good way to go, will be more forgiving wen it comes to extactor design too. A good friend of mine just made 240hp@wheels with exactly those mods & silvertop throttles!! Power was still going at 9000rpm! The dyno reads a little more than the one I use, but it still works out to about the same power as mine was.

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