Choosing ITBs

Ok so I am pretty sure I am going to go with individual throttle bodies on my Triumph. How do I go about picking out ITBs that will work with the engine?

This might help:

http://77e21.info/mstuning_tbsizing.htm

Once you determine the size you need, then you get to look around at what is available in that size and which works best for your proposed mounting solution.

If you're building your own intake, then use whatever bike TB's you want and design the intake around them. If you're using a DCOE style intake, then I would look at some of the DCOE replacement style ITBs as they are essentially a bolt-in solution.

Good luck! I'm looking forward to driving my ITB equipped car very soon. Tuning ITB's are a bit of a pain for a first timer, but they are damned cool :)

Good info - http://www.jenvey.co.uk/jenvey/throttle-body-selection-with-jenvey-dynamics

I'm in the process of fabbing some 42mm CBR954RR throttle bodies for a high CR D16A6.

I have an excel file that I made to determine the air speed through individual throttle bodies and compare it to one single throttle body. PM me if you'd like it. In my mind, it's the lack of air speed that makes part throttle modulation difficult in an ITB setup. I could be wrong (and probably am).

sounds right to me ross... I know vw/audi had a neat progressive TB back in the 80's... the tip in on a large TB is lets in A LOT more air then if you have a throttle plate 1/2 that size...

er here we are

I can probably get my hands on some GSXR 600 throttle bodies for cheap. I just wasn't sure if they would be enough for a 1296.

A 600cc 4-cylinder spinning at 10,000rpm will need quite a bit of air compared to a 1296 spinning at 5 or 6,000rpm ;)

I'm going to throw a set of triumph tt600 itb's on my 1.5L 9.8:1 5efhe paseo motor, going to rig up the original idle control compensator to run too.

I think the fuel cut on the GSXR's is something around 16k RPM. They should have no trouble feeding your 1300 even up to 8k, I'd think.

turboswede wrote: A 600cc 4-cylinder spinning at 10,000rpm will need quite a bit of air compared to a 1296 spinning at 5 or 6,000rpm ;)

By my calculations with volumetric efficiencies being equal (and assumed 1.0), a 600cc at 10,000 rpm will flow 106 cfm and a 1296cc at 6000 rpm will flow 137 cfm. Even at 5000 rpm the 1296 cc will use more air (114 cfm) than the 600 cc at 10k.

RossD wrote:

turboswede wrote: A 600cc 4-cylinder spinning at 10,000rpm will need quite a bit of air compared to a 1296 spinning at 5 or 6,000rpm ;)

By my calculations with volumetric efficiencies being equal (and assumed 1.0), a 600cc at 10,000 rpm will flow 106 cfm and a 1296cc at 6000 rpm will flow 137 cfm. Even at 5000 rpm the 1296 cc will use more air (114 cfm) than the 600 cc at 10k.

Recalc that at 16,000 and see what you get. :)

In reply to turboswede:

170 cfm. About what a 2.0 liter would flow at 5000 rpm.

-Ross "not trying to be a smart ass" D