johnbull
Expert Class
Posts: 314
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posted December 22, 2009 07:03 AM
OEM map sensor & fuel pressure, ok for boost?????
As I have already mentioned, we are in the process of fitting a supercharger to a ZX14 motor in a race car.
The supercharger is geared for about 7psi of boost plus we are fitting an intercooler.
Is the standard 'map sensor' ok to work on boost? If so, how much boost can it take?
Also, when running boost (7PSI) is standard fuel pressure ok or do you need to make any modifications?
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John Bul Racing. Malta.
  
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dubious
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posted December 23, 2009 07:29 PM
 Edited By: dubious on 24 Dec 2009 03:42
You have to bypass map sensor underboost, with a check valve in T so that pressure blows off, but the valve gets sucked closed so the stock map sensor only reads vacuum. It can not see any pressure.
If you run a blow off valve you will need to drill out the TB vaccum ports to 1/8" as they are like 1/64 " holes inside. Usless.
You can get Blow off refernce from the plenum, but your signal is much more accurate downstream of the throttle plates, so fueling will be more accurate as well there.
Since you are supercharged, wastgate plumbing is of no concern.
You will need a FMU with approx 7:1 boost to fuel pressure reference, and 100 psi fuel pump.
Personally I would do secondary 750 cc injectors and 1:1 boost reference with static set at 40 psi.
It shouldn't be to difficult to get a set second injectors for it, considering any 2stage turbo kit uses them.
Mine are from Chris Jones with Microtek standalone running batched.
They are zx14 specific with specific injector plates to mount them in the zx14 frame plenum.
You won't need anything that elaborate, just a second rail,microteck fuel box, and bosses welded into the plenum to mount the injectors.
I am not sure of the specific diferences in fueling for supercharged vs turbo.
I think Supercharged, have more parasitic loss, instant boost so more fuel is required to control AFR.
You should get in touch with Big CC,
They sell many supercharger kits for bikes, out of the UK.
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dubious
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posted December 23, 2009 07:42 PM
Edited By: dubious on 24 Dec 2009 03:43
guys have also ran FMU 7:1 fuel to boost reference, and stock injectors to about 9 psi on stock injectors with a 100 psi fuel pump.
One thing to remember with boosted engines, is its asking allot to hold one WFO like a naturally aspirated engine. The engine turns into a big heat sink and the pistons turn to mush LOL
Bigger cooling system, oil system and BIG intercoolers required to keep them alive for extened WFO pulls!
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natural selection.....
destiny will overcome intervention.
Some are not worthy of the effort.
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johnbull
Expert Class
Posts: 314
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posted December 27, 2009 10:48 AM
Thanks Dubious, will keep the map sensor modification in mind.
Re. ignition timing, some people say that I can leave stock and some people say I will need to pull back the timing. Whats your opinion? keeping in mind that I will be running 109 octane race fuel.
(ZXbob I know I already asked you this re. timing. Just interested to see what different people recommend as I know that ignition timing on forced induction is vital for the engine to stay together!!!)
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John Bul Racing. Malta.
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dubious
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posted December 27, 2009 08:00 PM
Edited By: dubious on 28 Dec 2009 04:01
stock timing, 109 octane, and 7psi , will be fine as long as you keep the CHT and EGT temps AFR reasonable.
Bob has more experience with boost than I do.
____________
natural selection.....
destiny will overcome intervention.
Some are not worthy of the effort.
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