Gsxr Throttle Bodies

[Batfink 201]

If the curve is enough you could run longer trumpets to get the length required. Certainly this is something I will look at in the future...

[Galifrey 1]

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.

 

Whatever its called, it is the pulse harmonics of the inlet we use to accelerate inlet gases, I am pretty sure Hemholtz applies as does Engelman's electrical analogy, although other than applying the formulas and making the calculations, most of this is beyond me.

 

There is a document about engelmans HERE although I don't have ppt on my laptop so cannot confirm whether it is any good or not.

[Cameron 16]

The last equation in that is hilarious.. I see something like that and my brain says yeah, no thanks.

[Galifrey 1]

The last equation in that is hilarious.. I see something like that and my brain says yeah, no thanks.

 

Ditto, can run the numbers, but lose the will to live part way thru

[Sandy 191]

I always make this point, because my experience reinforces it on a regular basis. I've yet to see a convincing "model" of inlet tract performance. There are so many variables at work, that it's pretty much incalculable. If you see how much the results can be changed simply by altering the trumpet lip radius for example, it all quickly becomes bollocks! I don't pretend to understand how it all works, but my belief is, that it's part flow efficiency, part acoustics and part pressure change. You can't simply focus on what the air might do either, the fuel is as important.

[Cameron 16]

So true. I'm sure the top F1 teams have built reliable models but we don't all have their kind of funding!

[Galifrey 1]

So true. I'm sure the top F1 teams have built reliable models but we don't all have their kind of funding!

 

F1 use a type of roller barrel throttle as butterflies don't really work above 15,000 rpm the theoretical butterfly position is too far away from the valve much above 15,000 rpm.

 

The trumpet radius is critical, as you want the trumpet to have as large an area as is efficent, but without drawing air from behind the trumpet to keep a nice flow pattern.

Edited January 6, 2010 by Galifrey

[sonofsam 5]

Just for the sake of it

[hcmini1989 16]

so for the injectors at the trumpet end could you use the bike injectors. allso how do you stage them in i.e to come in a wot or at a certain rev range etc

[Sandy 191]

The trumpet radius is critical, as you want the trumpet to have as large an area as is efficent, but without drawing air from behind the trumpet to keep a nice flow pattern.

 

Again, not just flow, but the effect on pulse tuning and hence fuel mixing, mid range, throttle response etc. It's become clear from my tests that the logarithmic-ish taper designs (eg Jenveys etc), are optimised for flow. Ironically, flow seems to be the least critical issue in the design.

[Galifrey 1]

Again, not just flow, but the effect on pulse tuning and hence fuel mixing, mid range, throttle response etc. It's become clear from my tests that the logarithmic-ish taper designs (eg Jenveys etc), are optimised for flow. Ironically, flow seems to be the least critical issue in the design.

 

Well if it pulls air from behind, it has a drastic impact on the flow, and upsets the pulse. I am suprised about the Jenvey issues, they make a big thing about the trumpet design.

[Dream Weaver 2]

The problem with bike bodies is that at first glance it seems like a cheap way to get yourself some bodies without splashing out on Jenvey's etc, but in the long run it's a ballache and costs almost as much.

 

If I could rewind back to my project I would have just stuck with the std ECU and induction and the car would have worked much sooner, and at less expense.

 

I was just pissing about when I did my project, I had lots of time as I wasn't a dad back then and I had s*it loads of spare money to burn but wanted to do it all myself as a learning tool. I did as much as I could with them, but they were never perfect and if I kept the car I would have scrapped them for std induction or Jenvey's.

 

The problem is, once you start on the bike body route you get to a point of no return, and the time and money needed after that gets worse and worse.

 

So, to answer the OP, I wouldn't bother with bike bodies UNLESS you have the time and skill to fabricate everything properly.

[hcmini1989 16]

The problem with bike bodies is that at first glance it seems like a cheap way to get yourself some bodies without splashing out on Jenvey's etc, but in the long run it's a ballache and costs almost as much.

 

If I could rewind back to my project I would have just stuck with the std ECU and induction and the car would have worked much sooner, and at less expense.

 

I was just pissing about when I did my project, I had lots of time as I wasn't a dad back then and I had s*it loads of spare money to burn but wanted to do it all myself as a learning tool. I did as much as I could with them, but they were never perfect and if I kept the car I would have scrapped them for std induction or Jenvey's.

 

The problem is, once you start on the bike body route you get to a point of no return, and the time and money needed after that gets worse and worse.

 

So, to answer the OP, I wouldn't bother with bike bodies UNLESS you have the time and skill to fabricate everything properly.

well mnes coming along nicely i havnt done any dyno runs or anything i dont expect to be making loads of power just did it because i could .as you said i had money to burn and alot of time on my hands .they are far from perfect

 

i have one question when you say they go out of balance .what do you mean do you mean the throttle openings un equal cheers for an advice

Edited January 11, 2010 by hcmini1989

[sideways danny 0]

i have one question when you say they go out of balance .what do you mean do you mean the throttle openings un equal cheers for an advice

 

if you dont solid mount them, the link between each throttle will move, so the amount they're each open at idle/low RPM will change (ok they will change everywhere, but it makes most difference at lower opening angle) this will cause rough running and a general poor state of tune

[DrSarty 90 1 Cars]

And reference the mention of 'bike injectors'. I'm not quite sure how you've managed to add or conclude that.

 

Bike injectors are both physically small and have a relatively low flow rate, because they're designed to function with engines (in this case) up to about 1300cc max, with 1000 or 1100 being the norm.

 

Injectors, single or staged need to be matched to your engine's displacement and expected power figures. For example, my 2.2 engine is running 2 sets of circa 220cc/min injectors. The outer set are pico injectors, as they are as small (length-wise) as bike injectors but have flow rates just like car ones, all the way up to stupid rates for mega engines.

 

The staging methodology I believe Sandy prefers is based on duty cycle, so for example when my inner set reach 50% the outers will join in. I will maintain better fuelling resolution across the rev range because neither set of injectors will have to be working very hard.

 

So in simple terms it's a 'no' to bike injectors.

Edited January 12, 2010 by DrSarty

[Galifrey 1]

And reference the mention of 'bike injectors'. I'm not quite sure how you've managed to add or conclude that.

 

Bike injectors are both physically small and have a relatively low flow rate, because they're designed to function with engines (in this case) up to about 1300cc max, with 1000 or 1100 being the norm.

 

Injectors, single or staged need to be matched to your engine's displacement and expected power figures. For example, my 2.2 engine is running 2 sets of circa 220cc/min injectors. The outer set are pico injectors, as they are as small (length-wise) as bike injectors but have flow rates just like car ones, all the way up to stupid rates for mega engines.

 

The staging methodology I believe Sandy prefers is based on duty cycle, so for example when my inner set reach 50% the outers will join in. I will maintain better fuelling resolution across the rev range because neither set of injectors will have to be working very hard.

 

So in simple terms it's a 'no' to bike injectors.

 

Busa Injectors flow 220cc/min Upgrade ones can flow up to 650cc/min so dunno where you getting your info from.

 

They may be for a smaller engine, but it is revving a lot harder and consumes a lot of fuel.

Edited January 12, 2010 by Galifrey

[DrSarty 90 1 Cars]

That's no doubt true Mark, but I'm talking in general. That's why I said 'in simple terms'.

 

A 'Busa isn't exactly typical, nor are they the bodies people are generally referring to here.

 

And upgrade injectors aren't standard either are they by definition.

 

So whilst you are right as you commonly are, I'm talking in general. So typical bike injectors used to working on a 750cc or 1000cc bike cannot possibly be working at optimum duty rate on a ~2litre engine even if they're staged. That is my opinion based on reasoning, and not fact.

 

I could be totally and utterly wrong, in which case feel free to point it out. I will always gladly admit my errors, even publicly.

[hcmini1989 16]

cheers for the help.i just assumed when you`s said staging that the outer injectors would switch off and not be used above a certain rpm hence why i thought you could use the bike injectors at low revs . the standard 750 injectors well for my bodies are 240cc/min at 3 bar .and from what i can tell the 600 injectors are the same .it seems alot of the bike injectors on over 600cc flow more than 220cc .

 

i see you say they have to be matched to the engine do you know if they have to be the same i.e both 220cc or could i run 220cc and a 240cc and do your injectors run of the same fuel table or are they diffrent cheers

Edited January 12, 2010 by hcmini1989

[Tom Fenton 1,542]

What is "optimum" duty rate? As far as I know, so long as the injector can provide the fuel that is required somewhere in the region of 10-90% duty rate, this is all OK. Outside of this region you need to go up/down on injector size, just to give either better resolution if running at 10% duty, or a safety margin of more fuel if running at 90%. Inside this range I don't see how it matters.

[Sandy 191]

Unless you get down to the minutiae of full sequential, with injectors timed to influence the charge in a certain way, but that's way beyond the scope of most of us with the amount and accuracy of testing needed. I aim to ideally have an injector set up that as a total will reach about 80-85% duty at peak power/rpm. Obviously having two sets that do that, mean that a single set at low rpm have much greater precision and with a batch/semi sequential, extending the opening time for a given fuel volume, seems to help mixing.

[Galifrey 1]

That's no doubt true Mark, but I'm talking in general. That's why I said 'in simple terms'.

 

A 'Busa isn't exactly typical, nor are they the bodies people are generally referring to here.

 

And upgrade injectors aren't standard either are they by definition.

 

So whilst you are right as you commonly are, I'm talking in general. So typical bike injectors used to working on a 750cc or 1000cc bike cannot possibly be working at optimum duty rate on a ~2litre engine even if they're staged. That is my opinion based on reasoning, and not fact.

 

I could be totally and utterly wrong, in which case feel free to point it out. I will always gladly admit my errors, even publicly.

 

Well I think you would be surpised, Blackbird injectors for example are around 300cc/min many bike injectors flow a lot more than you think and are designed to give a very good spray pattern.

 

When you are eaking so much hp from such a small engine the injectors need to be very good and very precise. My point about the upgrade injectors was that size is no indication of flow, you can easily get bike injectors that will flow huge amounts. A bike injector in an inlet tract (like ducati use I believe) is smaller so will have less of an impact on airflow, and has multiple jets for good misting of the fuel.

 

Like I say, do not base the performance on the size, there are 400bhp Turbo'd Busas out there running single injectors, they can deliver more than enough fuel when used in a staged system, and if you go for Blackbird Keihin injectors they get even better.

 

Bear in mind, a 1000cc engine at 13000rpm is flowing as much air as a 2000cc engine at 6500rpm so the fuel flow will be the same as well (roughly speaking)

[DrSarty 90 1 Cars]

Fascinating info.

 

When I said 'optimum', I didn't mean a specific fixed duty in percentage, rather as you've said (Tom and Sandy) an operating range with a limit, which I've always understood to be 80%.

 

Spray pattern too seems to be important, but depending on where the injector is located. When I found my Picos (Saxo VTS/106 GTI - IWPs) I did quite a lot of research on them, and there were about 4 different spray patterns available across the Pico range.

 

My inner injectors are GM V6 2.5 Bosch jobbies. I totally agree that it's not all about flow rate, and GTI6 injectors are good testament to that.

Edited January 12, 2010 by DrSarty

[Galifrey 1]

To my mind, whatever you are running, it will be properly mapped and setup, so all this info is fairly irrellevant, but for anyone else reading, it will be useful to know they dont have to replace the injectors just due to their capacity or resolution when fitting bike ITB's. There may however be other reasons not to use them (impedence for example).

[Cameron 16]

Bear in mind, a 1000cc engine at 13000rpm is flowing as much air as a 2000cc engine at 6500rpm so the fuel flow will be the same as well (roughly speaking)

 

Plus efficiency falls at high RPM.

[sideways danny 0]

What is "optimum" duty rate? As far as I know, so long as the injector can provide the fuel that is required somewhere in the region of 10-90% duty rate, this is all OK. Outside of this region you need to go up/down on injector size, just to give either better resolution if running at 10% duty, or a safety margin of more fuel if running at 90%. Inside this range I don't see how it matters.

 

resolution is very important, not using much larger injectors than you need is a very important piece of attention to detail. Just from a quick glance at my clio map, it idles around 3% duty on 230cc megane injectors and hits 90% at the limiter

 

80% rule of thumb may have been a bit influenced by a few glithes in old firmware versions on standalone units where they suddenly go 100% if you ask them to run over 80% even running 100% in a very few load points is fine, you're unlikey to hold those points for very long as they'll more than likely be right at the top of the revs at WOT, somwhere you'll only be for a few seconds unless you do top speed runs on airfields

Edited January 13, 2010 by sideways danny