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How much can u rise fuelpressure?

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Old 05 February 2003, 10:45 AM
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Denmark
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Hi All,
I´m at the end of my my99´s 440cc injectors (95-97% duty)
the Q is how much can you rise the pressure without going static still using a 1:1 rasingrate FPR?.

thanks
Skassa

PS:Who was that had the used/flowtested 550cc phase ll injectors for sale???
Old 05 February 2003, 12:19 PM
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Denmark
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Thanks John,

I´m currently using the oe lamdasensor for mapping, and it mapped for 0,89-0,90volt logged on my PClink.
The strange thing is that after instaling the manifold,there is now showing a reallylean spot at 2700/3000rpm.

from 3500rpm and up it needed some extra fuel.(exspeted)

I would realy like a wideband that can put out a 0-1v scale for use with the PcLink.(One that is accurate).
I don´t thing the rise in FP would be okay ones the frontmount goes on, so i can probely just as well buy thoose 550cc

Thanks

Skassa
Old 05 February 2003, 12:34 PM
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dowser
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Skassa,

You've the Tezet design headers, right? Fill the lean spot and the spool point will come down a bit How do you find them?

However, I got caught out once using OE lambda doing this - no matter how much fuel I threw in, it kept getting leaner. Lambda started failing same time as new headers went on...damned bad timing

I run my injectors at 95% with no apparent problems. But I do have 550's waiting.

Richard
Old 05 February 2003, 01:16 PM
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Denmark
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Richard,
I don´t know if it´s tezet design,but it´s the one that´s on supersprint.com´s side.
I will fill in the lean spot and see how it goes,
Right now it´s making 1bar at 3000rpm
I can´t really feal a diff,but i´m sure it´s becourse i had it back to standard for 2month(MOT time and then the wait for the manifold).Now it just flyes
The exhaust note has changed and the hiper is more pleasent to listen to
I´m still waiting for my knocklink and inletpipe from MRT,i´m now on my 2th month of waiting.(i will wait with the mapping til i get the things from AUS and just drive careful,the weather and all)
I have thought that my OE sensor is about to fall( I thing it´s acting strange).

Skassa
Old 02 May 2003, 11:24 AM
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john banks
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Pavlo had some 550s.

Apparently the rising rate FPR is more like 1:1 unless you get the motorsport version which is supposed to be a genuine 1.7:1.

A genuine 1.7:1 at 1.5 bar boost should give you approximately 3 bar plus 1.7*1.5 = 5.55 bar, which is a differential pressure of 4.05 bar.

This should give you 100*((sqrt (4.05/3))-1) = 16% more fuel.

I would not be averse to hitting 90% injector duty cycle at peak power. Also consider using a wideband to know you are not wasting fuel. I am running 11.8:1 at present and it works well with a FMIC at 1.5 bar.

Effectively you would also get about 16% more fuel if you put the static fuel pressure up to 4.05 bar.

I don't see the issue with mapping around a rising rate if you use a flat boost curve. If you taper it things will get more interesting. But injectors over 550cc are expensive.

[Edited by john banks - 2/5/2003 11:26:37 AM]
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