Gsxr Throttle Bodies

[danny56712 1]

Yeah you can fit the jets but they will still need fine tuning just like Webers will, and you're much more likely to find somebody who can tune Webers than bike carbs.

 

 

Wouls the theory of buying a set from a running mi16 in the same form be suffiecent

[Cameron 16]

I don't see why not, as long as it was running well on them. But I don't see why you want to cut corners so badly.

[Cameron 16]

Sandy and Colin's product.

 

 

I've been having a bit of a think about this (having just bought a set on eBay ) is there any reason why you didn't mount the throttle bodies closer to the head? I mean so that the manifold was shorter and the trumpets were longer, so the throttle butterfly was closer to the inlet valves. Did this layout prove to be the best through testing, or was it a compromise on space and ease of manufacture / available parts?

[welshpug 1,623]

I would imagine a lot is down to packaging, if you mount the bodies closer to the head they will be at a steeper angle, hence a long trumpet will be pointing at the bonnet, make the runners longer and the trumpets will be pointing at the grille.

[Cameron 16]

Ah yeah that makes sense, I suppose to have the bodies closer to the head you'd need a tighter bend radius on the runners. Sandy's radius looks close to the standard plenum so I guess is blends nicely into the port.

[Dj_mini 7]

Id imagine having the longer manifold also means the outer injectors are further away from the valve so helps mixing of the fuel / air.

[Galifrey 1]

Id imagine having the longer manifold also means the outer injectors are further away from the valve so helps mixing of the fuel / air.

 

And adds a lot of cooling to the inlet manifold

 

[Matt Holley 11]

Im probably wrong but Im sure that they are like that after alot of testing, the early bodies Ive seen were the other way round in lengh, mind you they were differant bodies.

 

I have a set ordered now

[Cameron 16]

Ah ok he still has the injectors in the bodies as well as the injectors in the manifold.

 

I guess the throttle response doesn't suffer noticeably by having the throttles further from the valves, it's still closer than the OE plenum's throttle is!

I was thinking about trying out 2 sets of injectors, not sure how to do it yet though! Thinking either infront of the trumpets in the airbox or between the trumpet and throttle body if I try and get the manifold short, or similar to Sandy's if I make it longer.

[Galifrey 1]

Ah ok he still has the injectors in the bodies as well as the injectors in the manifold.

 

I guess the throttle response doesn't suffer noticeably by having the throttles further from the valves, it's still closer than the OE plenum's throttle is!

I was thinking about trying out 2 sets of injectors, not sure how to do it yet though! Thinking either infront of the trumpets in the airbox or between the trumpet and throttle body if I try and get the manifold short, or similar to Sandy's if I make it longer.

 

Fire the primary set just behind the valves, and then use a set in the TB's?

[Cameron 16]

That's the plan if I make a long manifold, but if the manifold is short then the injectors would be quite close together so may need to be relocated in front of the throttle bodies. In all honesty I have no idea how far apart they would need to be though.

Edited January 4, 2010 by Cameron

[Galifrey 1]

That's the plan if I make a long manifold, but if the manifold is short then the injectors would be quite close together so may need to be relocated in front of the throttle bodies. In all honesty I have no idea how far apart they would need to be though.

 

Well the vaporisation of the fuel is what causes the cooling effect, so it will cool between its position and the inlet port.

 

You can centrally mount the injectors in the inlet trumpets, but they can be a fire risk if you backfire.

[Cameron 16]

Well, I don't mean for the cooling effect, I mean for improved mixture at high revs.

[Tom Fenton 1,526]

The injectors in the setup I mentioned are mounted out in the trumpets for that exact reason. The further away the better IMO.

[Cameron 16]

The further away the better IMO.

 

I thought that would be the case.

 

The Honda CBR seems to have a second set of injectors in the airbox, in front of the trumpets. That's what made me think of trying it out.

[Cloverleaf 1]

Here are the Triumph bodies I'm playing around with. 43mm and already built (extremely well BTW) to accept car injectors. They lozenge slightly too, like Batfink's touring car bodies. These will be rigidly mounted as discussed here and the spacing is almost bang on.

 

Currently a machinist I know with a 5-axis CNC is making some short stand-offs like the Jenvey/Weber ones, but as individual items. I'll also get trumpets end mounted, roughly at 100mm length which seems to be the norm. Other trumpet length advice appreciated.

 

These Triumph bodies are very nice pieces of kit, and just require 2 sets (i.e. 6) to make a set of 4. Other sets mean the spares can be used up, and the first set I got cost £18.

 

 

Which Triumph are they from? I don't recognise them

[Galifrey 1]

Which Triumph are they from? I don't recognise them

 

Look like 595 bodies to me

[DrSarty 90 1 Cars]

Look like 595 bodies to me

 

Yes. 1996 T595 Daytona.

 

As for Cam's recent points, I think we all agree now that length of inlet runners effects power delivery, i.e. shorter meaning pushing the power higher up the rev range at the expense of lower rpm torque availability.

 

Likewise, longer runners sacrifices peak power somewhat, but brings you great wallop down low and great tractability for road use, pulling (in my case) in any gear effortlessly.

 

The addition of staged injectors is for all of the reasons stated and one small bonus is a potential improvement in power in the high RPMs. However Sandy says it's not really a 'performance' methodology if we're talking peak figures.

 

The biggest benefit of staged injectors (as Sandy has explained to me) is throttle response - if mapped/phased correctly - and linearity due to achieving better fuelling resolution. It makes the power delivery smoother, filling in any slight gaps/dips, because you are not asking larger flow rate injectors at certain throttle positions to deliver very small amounts of fuel.

 

I'm not explaining it as well as Sandy does, so the best analogy I can think of is it being like a large person with fat fingers trying to do fine needle-point sewing; those hands are better at holding large rope. The twin injector approach is like having two people with smaller hands who will have more dexterity with fine stitching, but when working together they can still hold the rope just as firmly as the big fella.

 

Sandy says he prefers to map staged injectors based on duty cycle, and Emerald and DTA can do this straight out of the box.

[Sandy 189]

That's quite a good analogy.

[Cloverleaf 1]

Yes. 1996 T595 Daytona.

 

That was my logical guess, um....

[Cameron 16]

As for Cam's recent points, I think we all agree now that length of inlet runners effects power delivery, i.e. shorter meaning pushing the power higher up the rev range at the expense of lower rpm torque availability.

 

Well, to quote AG Bell it's the diameter of the runner that determines the peak power rpm (smaller = lower, larger = higher) and the length effectively "rocks" the power curve around that point. So if you had large diameter runners your peak power would be at high revs, you can then boost low rev performance with long runners, but then the power will drop off quickly after peak power; if you were to fit short runners then low rev power would suffer but you would hold peak power for longer.

[DrSarty 90 1 Cars]

Naturally I would bow to Mr Bell's infinite wisdom. I am a mere numpty.

 

Something to do with Hemoltz resonance anyway. In layman's terms I would guess that the longer inlet tracts favoured by most road cars are to increase/gain/maintain low end tractability anyway.

 

I certainly know that Sandy and Colin arrived at this design after many prototypes. It's an excellent combination for the road anyway, and just gets better with staged injectors.

[kyepan 291]

Naturally I would bow to Mr Bell's infinite wisdom. I am a mere numpty.

 

Something to do with Hemoltz resonance anyway. In layman's terms I would guess that the longer inlet tracts favoured by most road cars are to increase/gain/maintain low end tractability anyway.

 

I certainly know that Sandy and Colin arrived at this design after many prototypes. It's an excellent combination for the road anyway, and just gets better with staged injectors.

thanks for that rich,

 

helmholtz wiki

 

just read this in my lunch hour, most interesting.

 

J

[Batfink 201]

I've been having a bit of a think about this (having just bought a set on eBay ) is there any reason why you didn't mount the throttle bodies closer to the head? I mean so that the manifold was shorter and the trumpets were longer, so the throttle butterfly was closer to the inlet valves. Did this layout prove to be the best through testing, or was it a compromise on space and ease of manufacture / available parts?

 

I would hazard a guess that you would need curved trumpets which would be more expensive than a curved manifold

Jenvey do make some curved spacers though.

Edited January 5, 2010 by Batfink

[Cameron 16]

Oh, yeah they would be curved spacers with short trumpets.

 

I'm not 100% sure it's Helmholtz resonance that causes it, it's more down to pressure waves caused by the valves opening and when they arrive in the plenum. If it were 100% down to the plenum size then it would Helmholtz resonance, but it's the runner length and diameter that have the greater effect as that governs how quickly the pressure wave arrives in the airbox.

Edited January 5, 2010 by Cameron