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Author: Subject: st170 itb's query
leeby

posted on 9/1/18 at 09:59 PM Reply With Quote
st170 itb's query

hi im new here as was told by a friend you are the guys to ask.

currently building an st170 engine on gsxr 750 itb's for a mk6 fiesta project im doing (sorry not a locost), and im using the original st170 inlet, my query is and im sure its been answered a thousand times on here (and i did search), is with the vacuum pipes do i run them to a fpr also when using the st170 manifold do i put a fitting into say number four inlet for brake servo vacuum ??

absolute noob with itb's im afraid

also using acewell dash and have been informed there is a way of converting original gearbox pickup to work with the dash

thankyou

[Edited on 9/1/18 by leeby]

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SPYDER

posted on 9/1/18 at 10:17 PM Reply With Quote
Hi Leeby. I take it you are using the ST170 injectors? The little vacuum takeoff should be run to the FPR.
You might need connect all four runners to achieve sufficient vacuum for the brake servo. You'll probably need a vacuum reservoir too. And one way valves in the right places. Many ITBs don't hold much vacuum once they are opened even a small amount.
I put a bigger throttle quadrant on mine. The standard one is tiny and lends itself to on/off operation with little modulation.
Good luck with it.

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leeby

posted on 9/1/18 at 10:23 PM Reply With Quote
yeah im using original st injectors and thankyou for the info about fpr, the reason i asked about the brake servo is because a lot of aftermarket manifolds seem to come with just the one take off for the servo ?? ill be using or modifying original servo hoses with the valve in place.

and as im new to this most of what you said about it went straight over my head lol, but ill dig some more thankyou

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big_wasa

posted on 10/1/18 at 08:03 PM Reply With Quote
You know the fpr on an st170 is not an fpr but a damper ?
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leeby

posted on 11/1/18 at 10:13 AM Reply With Quote
yes im using a mondeo mk2 1.8 injection rail with st injectors, i prefer the mondeo rail as can swap supply and regualtor to either end for positioning and the supply is flexible unlike the focus one
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Angel Acevedo

posted on 11/1/18 at 06:33 PM Reply With Quote
quote:
Originally posted by leeby... is with the vacuum pipes do i run them to a fpr ...

[Edited on 9/1/18 by leeby]


Depending on ECU configuration, a connection to vacuum line may not be needed on a Normally Aspirated setup as necessary adjustments to Injector Fuel Flow are taken care of at the computer....


quote:
Originally posted by leeby... also when using the st170 manifold do i put a fitting into say number four inlet for brake servo vacuum ??

[Edited on 9/1/18 by leeby]


As stated above plenum and check valves may be the route...
A more accurate answer may be given if you factor brake effort at pedal according to preference.

[Edited on 1/11/2018 by Angel Acevedo]





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leeby

posted on 11/1/18 at 06:46 PM Reply With Quote
ecu wise ill be running a motorsport electronics ME221 but was told to use a fpr when i was originally going to use the gsxr 750 injectors, but have now changed that and am planning it running st170 inlet and injectors so id presume fpr will still be needed.
Using a mondeo mk2 1.8 zetec injector rail as they have a fpr and no messing about as would have had if using the st170 setup.

Its the brake vaccuum that is wrecking my head more than anything as aftermarket inlets have the take off for them and the st doesnt. my original servo to manifold hose has a oneway valve fitted, so do i use an 8mm barbed fitting from one of the intake or use same fitting in all intakes and daisychain them back to oneway valve and servo ?

i really dont want to build this car for a brake fail on first run

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SPYDER

posted on 11/1/18 at 07:43 PM Reply With Quote
You could always fit an electric vacuum pump to make your servo worries go away. Not the cheapest solution I grant you, but probably the most reliable.

And, trust me, reference your FPR to the manifold vacuum. If you don't the injectors have to work against a varying inlet pressure. This variation can be accounted for by the ECU, if very accurately mapped, but it can only do this by changing the pulsewidth. If your voltage compensation and dead time aren't set perfectly that compensation won't be correct.

AlphaN ( if you use it ) isn't a totally accurate measure of load at the best of times. Why introduce another variable.

I know the idea of having a fixed fuel pressure might seem tempting but ask yourself why most manufacturers don't do it.

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Angel Acevedo

posted on 11/1/18 at 07:46 PM Reply With Quote
Fuel pressure regulator will be needed regardless if you install vacuum line to it.
If the rail has no regulator, it may be part of the pump arrangement, either in-tank or external.
If your pump arrangement does not have FPR, you will still need one.

On your Vacuum line for brake servo, I will refrain to comment as someone may chime in with better knowledge than mine.





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leeby

posted on 11/1/18 at 08:06 PM Reply With Quote
thankyou guys
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