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Discussion Starter #1
I'm moving from internal fuel pressure regulator(integrated in fuel pump block) used on 156's 2.0TS and 2.5V6, to external FPR and Walbro 255 fuel pump.
Car in question is my trackday mid-engined 156, with 3.0V6 from 166's......
By far i used standard fuel pump and regulator - it seems that OE 156's 2.0 and 2.5V6 had 3,5bar FPR or at least 3.5 is stamped on it.
Because 2.0 20VT engine(from FiatCoupe) was used on that chassis for a while(total disaster BTW), Walbro 255 FP is still fitted on the fuel tank. And i want to use it.
Today i played with 2 different FPR's from 156's in order to see if there is any difference between it and aftermarket FPR......i just cut the plastic bonnet of the fuel pump block in order to use the FPR because it's integrated in the FP.
Autodata and few different sources shows 2.8 - 3.2 working pressure on 2.0TS and 2.5V6......FPR is 3.5Bar(or at least that's the mark on it)......2.0TS on Alfa 145 and 146 works on 3.5 - 3.8Bar - Autodata info again......and that's confusing.....because it's almost same engine.....
I measured 3.8 bars with both OE FPR's from 2.0TS pumps......i can guess that our service fuel pressure gauge may measure 0.1 - 0.3bars difference.
Is there someone that measured OE fuel pressure on at least 1 or two 3.0V6 engines(166's)??????
Or 2.0TS?????
Just need to be sure how much it is because i can not depend for sure Autodata and sources like it.
 

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I measured 3.5bar +/- 0.1bar resolution on the 2.0 TS with the older metal FPR mounted on the front fuel rail.

I also want to measure the fuel pressure on the 156 with integrated FPR in tank - I will see if I can get it done by next weekend - this weekend is out.
 

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Discussion Starter #3
Great - thanks....
 

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I measured 3.5bar +/- 0.1bar resolution on the 2.0 TS with the older metal FPR mounted on the front fuel rail.

I also want to measure the fuel pressure on the 156 with integrated FPR in tank - I will see if I can get it done by next weekend - this weekend is out.
Gertie I believe TN has done a test and gotten 3.5 bar at idle and 2.9 bar above 3000rpm on the 3.0 V6.
 

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I'd get another kind of regulator, one that references the intake manifold pressure so you can keep the fuel flow constant throughout the load and rev range. Only variable would be injection time.
 

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I'd get another kind of regulator, one that references the intake manifold pressure so you can keep the fuel flow constant throughout the load and rev range. Only variable would be injection time.
Fuel deposited into the cylinder is a function of the injection time AND fuel rail pressure. By applying a rising rate FPR (the ones that take manifold pressure into account) It lifts the rail pressure as the manifold pressure rises, thus you don't add as much injection time as you would to a static FPR (tank based FPR)
 

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Discussion Starter #8
Gertie I believe TN has done a test and gotten 3.5 bar at idle and 2.9 bar above 3000rpm on the 3.0 V6.
If i remember correctly 166's 3.0V6 use fuel pump integrated FPR which keep constant pressure - did he use external FPR???
 
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