Does anyone know if the vaccum take offs on my gsxr 600 throttle bodies will be big enough to feed my fuel pressure regulator and map sensor on ecu (if i join them all together with vaccum hose)



Cheers

Dave

i dont know on mine i use them for the map sensor and have a nomal adjusterable pressure regulator

Yes it will be fine, I have the same TBs and made some tee pieces from brake pipe silver soldered together and then joined up with rubber vacuum hose.
Paul

Cheers guys, thats good to know.

What did you do with the extra one (left hand side in pic).

mine are blanked off

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Originally posted by David_17
Cheers guys, thats good to know.

What did you do with the extra one (left hand side in pic).

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Will just one vaccum nipple be enough for the regulator? (standard zetec one)

Yes just join it to the pressure reg, it is connected to all the others internally.
Paul

Ah, think i've got it...

i'll have 4 nipples all joined together going to the ecu's map sensor. Then the tb with an extra nipple going to the fuel pressure regulator.

Is that right??

[Edited on 15/9/10 by David_17]

[Edited on 15/9/10 by David_17]

quote:

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Originally posted by David_17
Ah, think i've got it...

i'll have 4 nipples all joined together going to the ecu's map sensor. Then the tb with an extra nipple going to the fuel pressure regulator.

Is that right??

[Edited on 15/9/10 by David_17]

[Edited on 15/9/10 by David_17]

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Sorry chaps, going to disagree with a few of you. None of the tappings are "internally linked" within the throttle bodies, assuming they are the early separate TB's. It's possible they are linked within the manifold but rather unlikely. What this means is that the extra one only senses the pressure in TB number 3, which fluctuates depending on the cycle of the engine. If you connect this to your powerboost fuel prv, or similar, it will cause the fuel pressure to oscillate at the same frequency. To test this, run the engine with a fuel pressure gauge fitted. Much better with bike TB's on a car to blank this one off and vent the prv to atmosphere, you can achieve much the same effect as a powerboost prv with fuel mapping.

Moving onto the other 4 ports; if you insist on using MAP to sense the load, then connect them all together and hope the signal is smooth. It probably won't be, and some users (expect them to come along shortly) will damp the signal with welding nozzles, fuel filters, and all sorts. However, the best solution for a small-ish high revving engine is to use throttle position sensing as the load sensor and don't bother with the MAP signal at all (unless the engine is turbocharged, and then you will need pressure feedback). One of the reasons with bike TB's, especially GSXR's, is that they will idle at around 50mB pressure, however as soon as you crack them open the manifold pressure will increase to around 94-95 mB, with some ripple on it, and leave you with only 3 or 4 mB over which to try to map the whole of the throttle range. As if by way of reinforcing this, look at any high performance race engine of similar genre from Dunnell, Raceline, Scholar, etc, none of them use MAP for load sensing, always TPS.
So, my advice is block the whole lot off, let the prv vent to atmosphere and use throttle position sensing for your load detector unless the engine is boosted.
There's more about it on my website, link below.





[Edited on 16/9/10 by fatbaldbloke]

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Originally posted by fatbaldblokeMuch better with bike TB's on a car to blank this one off and vent the prv to atmosphere, you can achieve much the same effect as a powerboost prv with fuel mapping.

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The problem with this is you get a higher pressure drop across the fuel injectors at idle than you do at WOT, which isn't helpful in keeping injector pulse widths at a reasonable level at idle.

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I actually run mine like this, all the take offs are linked and connected to both the MAP sensor and the PRV, but after trying to run MAP for a while I now use Alpha -N and just let the manifold pressure regulate the fuel.
Paul

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Originally posted by fatbaldbloke

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The problem with this is you get a higher pressure drop across the fuel injectors at idle than you do at WOT, which isn't helpful in keeping injector pulse widths at a reasonable level at idle.

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I wouldn't disagree, what you say is quite correct. My own experience of running a powerboost prv vented to atmosphere however is that I haven't had a problem, and I'd suggest a stable vent to atmosphere is better than a fluctuating pressure to a single tapping in one throttle body. However, if one accepts that throttle position is the better load indicator than manifold pressure, so you don't need a MAP signal at the ECU, there's no reason why one couldn't use the linked pipes from each throttle body to set the vacuum in the prv. That might be a decent solution, although I haven't tried it myself. So, block off the single outlet, and connect the other 4 outlets together using this to control the prv.



[Edited on 16/9/10 by fatbaldbloke]

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That sounds like the best option to me. Will i have to do anything with the map sensor if using tps mode? Plug it off or just leave it?

Cheers

Dave

I'm assuming you're thinking of using megasquirt, where the sensor is on the board. If so just leave it open. Depending on the ECU you can use it to adjust for atmospheric pressure if you're really fussy. Might be needed if you do Pike's Peak....

[Edited on 17/9/10 by fatbaldbloke]