Hurdy's Golf .:R.

[Hurdy]

Hurdy, I saw your Santa Pod race with the V8 Chevy drag car an it was really impressive. 
I have a very very fast car  .

Cheers Rex. Next time it will be quicker. 

[Hurdy]

Update....

Did a few logs in the last few days and found out the MAF maximum reading is 364.08g/s. The GIAC map I run is scaled based on a larger MAF diameter which I am also running. The cross-sectional area is 10% larger and so I'm guessing that this scales the MAF reading by 10%, which basically gives 400g/s. Hopefully after this the map adjusts.

Quick shot of the log.

I thought yo would have been running the rail pressure at a higher value tbh.  The APR Stage 3 setup uses around 150bar iirc

I think we will stick with a lower fuel pressure and go for 8 injectors and a controller instead. Sky's the limit then. 

[Janner_Sy]

I think we will stick with a lower fuel pressure and go for 8 injectors and a controller instead. Sky's the limit then. 

   I was under the impression that the higher rail presure gave more headroom for the injectors.

[Hurdy]

I think we will stick with a lower fuel pressure and go for 8 injectors and a controller instead. Sky's the limit then. 

   I was under the impression that the higher rail presure gave more headroom for the injectors.

Puts extra stress on other parts like the HPFP though.

[Janner_Sy]

Puts extra stress on other parts like the HPFP though.

But if they are designed to run above 150Bar why not run the pressure at say 145Bar leaving plenty of headroom?  Look at the difference between a stage 2 and stage 2+ K)4car, surely there are big gains to be had especially at your level of tune.

Id have thought you would need a higher rail pressure in order to run 8 injectors anyway as your essentially doubling the amount of fuel that can be injected.

[rex]

I meant "You" have a very fast car, not "I":

Hurdy, I saw your Santa Pod race with the V8 Chevy drag car an it was really impressive.  
You have a very very fast car   .

[Hurdy]

Puts extra stress on other parts like the HPFP though.

But if they are designed to run above 150Bar why not run the pressure at say 145Bar leaving plenty of headroom?  Look at the difference between a stage 2 and stage 2+ K)4car, surely there are big gains to be had especially at your level of tune.

Id have thought you would need a higher rail pressure in order to run 8 injectors anyway as your essentially doubling the amount of fuel that can be injected.

Pressure and flow are linked to an extent in terms of delivery of fuel. Ultimately a higher fuel rail pressure will deliver a little more fuel, but think of it as trying to blow water down a small straw, you will get a constant flow at a relatively low pressure, but when trying to blow harder you just end up flowing a similar amount, but giving yourself a bust blood vessel doing it. It is finding out at what point to stop increasing pressure that is key. Maybe more fuel rail pressure will work, maybe it will just end up stressing the system. I'd rather work things up by adding injectors and then build the pressure, rather than the other way around. 

[vRSAlex]

Currently running a K1 at 155 bar that raises to 160 bar at times.  That's on a loba pump.

The extra four injectors only need to run at around 5 bar as they are normal injectors. Extra ecu needed to control them is the downside.

[Hurdy]

Is there a need to run it at 155bar though? I'm running more power and still at 135bar with no issues.

[danishmkvgti]

Is there a need to run it at 155bar though? I'm running more power and still at 135bar with no issues.

Main reson for the higher pressure seems to be to avoid running the RS4 injectors and stay with the S3 injectors with the right spraypattern. APR claims that S3 injectors supports up to 500bhp, i assume that's with higher high fuel pressure

[Hurdy]

Is there a need to run it at 155bar though? I'm running more power and still at 135bar with no issues.

Main reson for the higher pressure seems to be to avoid running the RS4 injectors and stay with the S3 injectors with the right spraypattern. APR claims that S3 injectors supports up to 500bhp, i assume that's with higher high fuel pressure

Yes, and this is part of where I was leading to. People are saying that S3/R injectors flow more than the RS4 injectors, if they did then why do they have to run a higher pressure?

[Pikey Motorsports]

Apr also modify the s3 injectors they dont fit them out the box

Personally i dont belive the s3 injectors flow more as they come

[vRSAlex]

Is there a need to run it at 155bar though? I'm running more power and still at 135bar with no issues.

More headroom.  No smoke.

If you can use higher pressure then you might as well.

[danishmkvgti]

Is there a need to run it at 155bar though? I'm running more power and still at 135bar with no issues.

More headroom.  No smoke.

If you can use higher pressure then you might as well.

Also the EA888 engine has 150Bar as stock, (although the pump is of a different design)

[Janner_Sy]

Which is the reason the EA888 engine tends to make more power st KO4 and stage 3 big turbo upgrades