Technical 34mm ITB's in the post :)

[fingers99]

Yeah, I can't see them as being too big. I gave Brooky a hard time over the sizing of his, but now I hear of people using 54mm ITBs on 2 litre Frauds, without any issues other than the progression off idle being a bit sharp. Strangely, I was peeking at the TB off an MPI Sei the other day, and I'm pretty sure that the throttle pulley is cam shaped (presumably) to avoid just that (didn't get round to measuring it.)

 

[Eklipze3k]

That looks like fun

 

[Brooky]

how are you mounting theses??

looks alot easier than mine as your spacing looks perfect, abit of silicone hose or are you going to make a manifold?
also how are you getting air to them?

Im mounting mine in a down draft position and a vent in the bonnet. Might look gash but it should work

 

[Adrian Bravo]

Cool! Whats the TB from?

 

[randomizered]

These are from a BMW K100 motocrcyle.

I haven't looked into nounting in much detail, but as they space up so well, I'm thinking of have a flange machined up, some straight ports about 10cm long (housing injectors and fuel rail) angled to match the flow into the head, then FluoroSilicone clamped on both sides of the throttle bodies as you suggest. Shoul make a sturdy connection.

Alternativly, i may have them mounted slightly closer, and have the injectors after the throttle plates. Sur it's further from the port, but will be a lot easier to have made.

Trying to keep costs down is my main goal, as i don't have the equipment to make it myself.

WIth reagrds to air, I will start with an open filter under the bonnet, so they are sucking in warmish air (purely as it's easiset). IF it works ok, i will fit the largest volume box i can and runa cold air feed from the front of the car.

Kristian

 

[hot_fiat]

Looking good. k100 stuff is rare as roking horse poo as the head's a fairly easy way to do a 16v conversion on an A-series lump.

This is my manifold & bodies.

 

[craigb244]

Yeah, I can't see them as being too big. I gave Brooky a hard time over the sizing of his, but now I hear of people using 54mm ITBs on 2 litre Frauds, without any issues other than the progression off idle being a bit sharp. Strangely, I was peeking at the TB off an MPI Sei the other day, and I'm pretty sure that the throttle pulley is cam shaped (presumably) to avoid just that (didn't get round to measuring it.)

Youll find ALL engines have cam style of some sort on they throttle. cars usually have it on the tb but bikes usually have it on the twist grip.
for common bikes you can buy different twist grips that change the throttle openings to tweet to your riding style.

4strokes usually have a "cam" that progressively gets larger to help with off throttle stumble and better control over the higher torque output. Then take a look at a 2stroke "cam" it usually opens loads quickly then tappers "wider" around the middle to upper positions

I look forword to megasquirt (hopefully) been able to have fly-by-wire where you will be able to tweek this "cam" to make the car very drivable

 

[fingers99]

I can find no cam effect -- not exactly the right word for it, but a design to make the initial throttle opening gentler (have less effect on the butterfly) -- on the K series TB in front of me there isn't one, no Ducati I ever worked on had one (and I worked on everything from the singles to the 888), and I'm pretty sure that the SPI Cinq and Sei don't have one. Damn sure my RD250 didn't have one either.

Now, if they were that common, why would Dave Walker wax lyrical on the benefits of having them, why would A Graham Bell waste a page describing how to make them?

 

[hot_fiat]

KTM have only recently started to sell different cams for their throttles:

 

[craigb244]

I can find no cam effect -- not exactly the right word for it, but a design to make the initial throttle opening gentler (have less effect on the butterfly) -- on the K series TB in front of me there isn't one, no Ducati I ever worked on had one (and I worked on everything from the singles to the 888), and I'm pretty sure that the SPI Cinq and Sei don't have one. Damn sure my RD250 didn't have one either.

Now, if they were that common, why would Dave Walker wax lyrical on the benefits of having them, why would A Graham Bell waste a page describing how to make them?

I doute you have ever took a twist grip apart then. pretty much every one ive seen has a cam effect to it. even my BSA!! I had 3 throttle tubes for my suzuki all OEM one from a road bike with the same engine, one from a Dual sport and one from a pure offroad model.

KTM have only recently started to sell different cams for their throttles:

KTM might of "only" just started to sell them but they have been out for years

 

[fingers99]

I doute you have ever took a twist grip apart then. pretty much every one ive seen has a cam effect to it. even my BSA!! I had 3 throttle tubes for my suzuki all OEM one from a road bike with the same engine, one from a Dual sport and one from a pure offroad model.

I've taken plenty apart: I've even made quick action ones, rather like the one bottom right, which doesn't seem -- from the pic -- to have any cam effect.

But I'm not really interested in talking about BSA and Suzuki.

 

[randomizered]

Looking good. k100 stuff is rare as roking horse poo as the head's a fairly easy way to do a 16v conversion on an A-series lump.

This is my manifold & bodies.
...snip

Looking nice

WHat size throttle plates are they?

wrt the K100 stuff, they just looked small and were the cheapest BIN on eBay, so I bought them on those grounds only.

Yours looks a nice setup though, as you don't have the issue of mounting injectors like i do. I knew that would be an issue when i bought them though.

When are you fitting them?

 

[randomizered]

balls, fook, bugger and aaarrrgghhhhh.

Spent a few hours today, stripping down the ITB's. done 3, lovely and clean, all seals check, ultrasonicly cleaned etc.

stripping the last one, and the thread on the brass shaft stripped due to a tight nut :bang: I can't strip it apart, and therefore can't clean it up properly, and so i'm scrapping them, or keeping the other 3 as spares if i buy some more.

Not a happy chap right not. At least they were relativly cheap, though i could have done better things with £25

Kristia

 

[Todger182]

Bugger. Is there any way of drilling the bolt out and re-tapping?

Thanks

 

[randomizered]

No, it's the thread on the brass shaft that holds the butterfly in, why couldn't the nut have stripped instead, easy fix then.

Ah well, i'll concentrate on other things for now.

Wondering about fitting other heads to the block now

 

[Todger182]

Oh god.... lol. Thats an interesting thought actually.... Would any of the alfa ones fit like 155 or 147, maybe a 145 cloverleaf?

Thanks

 

[Todger182]

Crap scrap that, just remembered that some of them use the boxer style engine.....

Thanks

 

[randomizered]

If at first you don't suceed, try try again



They are soaking in lubricant now, to break up all the dirt, and make sure they come apart easily.

At least I have spare parts from the old set as well

Once they are stripped down, cleaned, new seals, I shall be approaching an engineering firm to get a manifold made. Gonna be quite expensive I imagine, as i will need injector bungs installed, adn a fuel rail mounted. Any idea what ballpark I'm looking at? £150 tops I hope, but I have NO clue as to what it will really cost.

Also need to source a throttle position, because this one is only a throttle position switch.


This set came with the airbox, filter etc. with it, so I may link the airbox to my BMC CDA, or run some filter socks? Anybody got any ideas about this?


Cheers,

Kristian

 

[randomizered]

I know someone else, has these TB's as well, so I'll post up some information on the TPS.

This is the BMW TPS:

BMW: 13-63-1-273-265
Bosch P/N: 0-280-120-302



No use to me, as it only makes a switch at Closed and WOT. As the MAP signal will be quite poor with ITB's I'll definatly need a variable resistance output.

I can't find anything as a direct replacement after trawling the web.

Something similar is the BOSCH 0-280-122-001 but it's NOT a direct fit. I think the shaft will fit, but the bolt holes will not line up.

View attachment sensors_throttleposition.pdf

I may buy one and just modify it, or keep searching for something else.

Cheers,

Kristian


EDIT - 0-280-122-001 ordered for a few ££, so I will have a play. I have read the shaft will def fit, but the mounting holes are too close together. Should be VERY easy to make up an adapter, or maybe swap the housing over for a neater look.

 

[craigb244]

Kristian,

Have you looked into injector position in the tract? the distance from the port will greatly effect how the engine responds at certain rpms.

also on the TP thing. you planning on using hybrid Alpha-N?. thing is I recon unless you are running stupidly lumpy cams then Speed-Density will be fine.

also Id recommend porting each tb to the next. it will let small differences in balance between the TBS equalize. should make a huge difference to idle.