Looks like VAST offers two 5 bar FPRs. One is $127. The Bosch Motorsports one is $298. Any
11-20-2007, 11:29 AM
#1
AudiWorld Super User
Thread Starter
Looks like VAST offers two 5 bar FPRs. One is $127. The Bosch Motorsports one is $298. Any
insight? I'm looking into going Stage 3- (minus), so I of course need a 5 bar FPR. Is the cheaper one on Vast's website the "crushed" 4 bar thing, or a real 5 bar FPR that's just not from Bosch Motorsports?<ul><li><a href="http://vastperformance.com/shop/product_info.php?cPath=26&products_id=38">http ://vastperformance.com/shop/product_info.php?cPath=26&products_id=38</a</li></ul>
11-20-2007, 11:39 AM
#2
Both EPL and GIAC recommend the real Bosch Motorsports true 5 bar fpr for their 3- software
I guess the crushed 4 bar isn't accurate enough or isn't quite 5 bar (don't know the specifics behind it). But with 3- you're really pushing your fuel system to the max so you want to make sure you really have all the fuel pressure you can get. Not a good place to skimp IMO.
11-20-2007, 11:41 AM
#3
AudiWorld Super User
Thread Starter
I know, but their website offers 4 bar, 4.25 bar, 4.5 bar, 4.75 bar, and 5 bar FPRs and then the
Bosch Motorsports 5 bar in addition to those. I tend to trust VAST so I was just curious if their non-Bosch Motorsport 5 bar FPR was a legit option.
11-20-2007, 11:47 AM
#6
Not bashing at all. Just restating what both GIAC and EPL have said.
And fuel pressure is one thing I'd rather not test the tuners knowledge/recommendation on. Additionally, neither makes a profit on the 5 bar anyway, since it's made by bosch. That is unless they own stock in bosch....
Not to mention the true 5 bar is only $170 more. Really not all that expensive in the whole scheme of things.
Not to mention the true 5 bar is only $170 more. Really not all that expensive in the whole scheme of things.
11-20-2007, 11:51 AM
#7
thousands of 1.8ts run everyday with crushed 4bar FPRs->5bar.
its common, proven and tends to work fine.
in general, 5bar anything is not a great idea, bosch motorsport or not.
get the cheapo crush, and save money for a real fueling setup (injectors + lower fpr)
in general, 5bar anything is not a great idea, bosch motorsport or not.
get the cheapo crush, and save money for a real fueling setup (injectors + lower fpr)
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11-20-2007, 12:20 PM
#10
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Crushed 5 bar fpr's do not function the same as a true 5 bar bosch fprs will......
Factory style fpr's are boost referenced...
What this means is as boost increases so does rail fuel pressure. In a true 4 or 5 bar fpr the reference is nearly 1 to 1. So 1 psi of boost = roughly 1 psi of fuel pressure.
Once you crush an fpr it is no longer ~1 to ~1. This will lead to fuel pressure higher then 5 bar.
What this means is as boost increases so does rail fuel pressure. In a true 4 or 5 bar fpr the reference is nearly 1 to 1. So 1 psi of boost = roughly 1 psi of fuel pressure.
Once you crush an fpr it is no longer ~1 to ~1. This will lead to fuel pressure higher then 5 bar.