Don@STaSIS

Howdy! I just did some quick calcs for someone using 37lbs Racetronix injectors and wanted to confirm:

ADU (RS2) Injectors:
360 cc/min @ 3.0Bar
405 cc/min @ 3.8Bar
<b>416 cc/min @ 4.0Bar</b>

Racetronix 37lbs Injectors:
391 cc/min @ 3.0Bar (37.27lbs/hr*10.5)
440.05 cc/min @ 3.8Bar (Sqrt(55.1psi/43.5psi)*391cc/min)
<b>451 cc/min @ 4.0Bar</b> (Sqrt(58psi/43.5psi)*391cc/min)

So the Racetronix are definitely bigger injectors.

My solution for software that uses the RS2 Injectors and stock 4Bar FPR would be using an adjustable fuel pressure regulator and setting pressure at:

<b>416cc/min @ 3.4Bar (49.3psi)</b>
(Sqrt(49.3psi/43.5psi)*391cc/min)

Using 1Bar = 14.5psi and 10.5 to convert from lbs/hr to cc/min.

Just wanted someone to confirm and also start a discussion about running lower fuel psi with the 37lbs injectors to emulate the RS2 Injectors for software that requires them. Adding an adjustable FPR and gauge would allow someone to dyno multiple software types that require different injectors with one type of injector installed.

Comments, suggestions, errors?

Thanks,

spiralsmurf

good idea because this way non-MRC chipsets if one should desire

VR_Life

<A HREF="http://www.rceng.com/technical.htm">RC Engineering - Formula work-sheets</A>

<A HREF="http://www.tyrolsport.com/vwperformance.htm">Bosch Adj FPR</A>

I'm installing Bosch #39 Type6 Injectors (cause they easy/cheap to get them flow-matched) so I'm in the same boat.

Don@STaSIS

it opens up more chipsets to be run. I am mainly interested in testing chipsets side by side on the dyno to get numbers down for my own brain and for everyone else. If I can turn a nut and screw, turn the FPR down and pop in some software that is for RS2 Injectors that would make it very easy.

I am curious to know if anyone can think of any side effects of doing this, poor atomization or something else. The 37lbs are rated at 3Bar already, so 3.4Bar seems like a fine psi to run at.

Cheers,

cpayne

Really w/o it sort of hard to tell what your mixtures look like exactly.<ul><li><a href="http://www.zeitronix.com/order/order.htm">http://www.zeitronix.com/order/order.htm</a</li></ul>

Don@STaSIS

so really in theory with an accurate gauge the fuel pressure could be set to yield the proper cc/min and then it should be fine. At the least I would use a basic A/F gauge and would prefer a wideband for sure. Though as mentioned a specific fuel pressure can be attributed to a specific injector flow rate which will match with the software. In theory just changing the pressure and doing some math should work, but we all know how that goes

On a dyno with a standard A/F gauge and a sniffer in the tailpipe for A/F I'd feel safe going without a wideband, but again I'd prefer to have one in hand to be safe and confirm the software is being run as intended so any comparisons on software are fair.

Cheers,

repeater

My MRC set runs very rich with the Racetronix.

VR_Life

so then the question is does the injector produce the same flow as MAP changes from vacuum to boost ?

I believe the answer is no, because the FPR does a linear add (Fuel Pressure increases Linearly with MAP) but the FPR/Inj equation is really a Root-Mean-Square of flow for given injector duty cycle.

So Linear vs Parabolic = doesn't match, and you'd need the A/F ratio's to make sure you don't lean out at the top end.

I put a bung in my downpipe, and am going to use Innovative Technologies LM1 A/F Logger + LMA-3 I already had for tuning my B5 S4<ul><li><a href="http://www.innovatemotorsports.com/products/lm1.php">Innovative LM-1</a></li></ul>

Don@STaSIS

is how the charge air pressure will effect the flow of the injectors. If I do an Innovative product I will grab the 034EFI Standalone WB Kit. It's a real nice piece and easy to mount/deal with.

Thanks for the input! Really this is what I wanted to hear, at least a confirmation that it wouldn't be a simple one to one relationship.<ul><li><a href="http://www.034efi.com/product_info.php?products_id=189">034EFI WB Kit</a></li></ul>

Don@STaSIS

<b>RS2 Injectors</b>

416 cc/min @ 4.0Bar (58psi)
434 cc/min @ 4.34Bar (63psi)
450 cc/min @ 4.69Bar (68psi)
467 cc/min @ 5.03Bar (73psi)

<b>Racetronix 37lbs (451 cc/min @ 4.0Bar)</b>

416 cc/min @ 3.4Bar (49.3psi)
436 cc/min @ 3.74Bar (54.3psi)
456 cc/min @ 4.09Bar (59.3psi)
475 cc/min @ 4.43Bar (64.3psi)

So actually it's going to add a tiny too much fuel for software designed for RS2 Injectors, so actually "safer."

Does anyone know the relationship between boost and fuel pressure with the stock Bosch units or the Eurospec adjustable unit from 034EFI that Cody is running?

Comments?