View Full Version : 4bar FPR instead of stock 3bar FPR for 20VT
I have been told, that replacing the stock 3 bar fuel pressure regulator to a 4 bar one (same size/OEM VW part) will give you some more "oomph" besides being a fairly simple, relatively cheap mod. (for chipped cars of course).
Is that ture???
Read a fair bit about it on http://forums.vwvortex.com/zeroforum?id=27.
Also APR change to 4bar for their Stage 3 kit.
Is it only sensible if your injectors are maxing out?
Be aware that vag-com's dyno feature wont report correct torque figures anymore if you put in a 4 bar FPR
Ian
you have got your turbo pretty much maxxing out? Have you tried using VAG-COM to see how much it thinks your bhp is?
I see. Though i dont have vagcom, sadly. I'm wondering if it does any harm to the engine/would fool ECU.
Dave,
I have done some dyno plots at 21psi and my 3second power levels at 5krpm are 223Bhp (heatsoak takes it back down after this), I could get them there permanently if i put a 'c' version N75 in and upgraded to a front mounted intercooler,
But as i wount be keeping this car for too much longer i'm not going to bother!
Sim,
It doesnt do any damage running with a 4bar fpr but unless your chip is specifically mapped for it you will get noticeably higer fuel consumption, you will get more power though becuase you will be able to run more boost
thanks Mosser. I got a "C" valve ;)
If youv'e got a computer in the car giving fuel consumption this will read wrong as well, as it is putting in more fuel than it thinks.
Originally posted by Mosser
I have done some dyno plots at 21psi and my 3second power levels at 5krpm are 223Bhp (heatsoak takes it back down after this), I could get them there permanently if i put a 'c' version N75 in and upgraded to a front mounted intercooler,
Interesting, makes sense. Worth people bearing that in mind if they are going for the major power levels (bigger turbo). I seem to remember reading that the twin intercooler setup is actually very efficient.
Is there anyway to detect how much the ECU is holding back power (because of heatsock/knocking)?
Hi
Higher fuel rail pressure will lead to more fuel going into the car at a given injector opening time (the injector opening times are programmed in the ECU)- if you dont put more air in then the mixture will richen and if this is dramatic you will get bore wash and knacker your engine (bore wash=oil that lubricates cylinders washed off by excess fuel). If you increase the boost pressure, I guess you may put more air in but that depends if the head will flow enough air. Basically its very hit and miss and unless you have examples of knowledgeable people who have done this and checked the results with an exhaust gas analyser I would not do it - the only way to do it is map the engine properly.
Also, as the engine runs with a lambda sensor, if it detects a high fuel:ox ratio, I think it will back off the fuel and bring it in line again - BUT - this moderation is usually only limited and it may not be able to back off the fuel enough if the engine is dramatically rich.
Proper mapping on the rollers is the only real safe way to muck about with engines nowadays..
Cheers
Rob
I believe you can monitor the ingition advance using vag-com, this should give you an indication of how much it is holding back
Originally posted by DaveP
Read a fair bit about it on http://forums.vwvortex.com/zeroforum?id=27.
Also APR change to 4bar for their Stage 3 kit.
Is it only sensible if your injectors are maxing out?
This is a sensible mod if the injectors are at >90% duty cycle - above this to get more fuel either get bigger injectors for a constant line pressure or increase line pressure (cheaper than new injectors) Only sensible if done with proper exhaust gas analysis etc etc
Cheers
Rob
I believe you can read the A/F ratio and inject duty cycle off VAG-COM.
Injector duty cycle is definatly in there, but i've never seen the af ratio