Hi guys, following on from this thread, I got around to comparing the sizes of the Triumph throttle bodies (the 42mm diameter versions) and the Jaguar intake ports. The image below shows the results:


Description

As can be seen the difference between the Triumph intake area (1385.44mm^2) and the Jag intake ports (1436.55mm^2) is pretty small, so I'd say there's no real restriction there. The issue is that the Triumph TB's taper down into the profile shown, which only has an area of 1152.3mm^2 - about 20% or so smaller than the Jag ports. I can blend out the differing profiles over the 25mm thickness of the adapter plate, but what I've effectively done is create a venturi, speeding up the airflow around the injectors and then settling it down in the cylinder head.

My concerns are that this venturi shape will restrict airflow, create unwanted turbulence (especially considering the relatively short distance available to re-shape the ports in the adapter), and that the resultant gas velocity will be too low.

Am I looking into this too much, or should I just call it and find some new ITB's (or even just build a new intake tract)?

[Edited on 21/2/15 by Badger_McLetcher]

I have had a quick look at this before, I would be temped to go for the more traditinal gsxr type throttle bodies, make up mild steel flat adaptor plates with holes to match the jag ports, get some pipe of the same cross sectional area as the jag ports, squash one end to fit the holes in the plates and weld it up leaving some short stubs to attach the throttle bodies. if this all works out then you can get it re-made in ally (unlunless you have the facility to weld ally, if so go straight for that). This would use the jag injectors insitu or ones In the throttle bodies.

Worth cading it up and getting a quote from lasermaster for the plates in ally and mild steel (10mm) I have found then very good and reasonably priced.

When you add the butterflies and spindle you are maybe looking at 20% smaller, I would put them back on eBay and get something a bit larger unless you can spin them out in a lathe. How big are the butterflies in them.

The butterflies are about 41mm in diameter. I looked at boring out the bodies but the wall thickness next to the injectors is only about 4mm - not enough for an even bore. An off centre attempt may work, but I haven't the time, equipment or expertise for that.

Anyone after some Triumph throttle bodies?