The Cummins 4bt VE and the TDI VE, fuel pressures

jhaas88

Active member
Joined
May 21, 2010
Location
IL
TDI
Looking
As I have read on here, the TDI VE is an electronic version of the Cummins 4bt VE. In fact, on older engines, the only difference I have seem to have found is the shaft size (IIRC, the VW VE is 15mm, the Cummins is 20mm). So for sake of argument, lets say they are mostly the same. The reason for this thread is to find out WHY the fuel inlet pressure are lower on the VW vs the Cummins VE.

I will quantify this with me having a 1993 Cummins 6bt. I have a Walbro 392 HPFP with a Mallory 4307M regulator set at 16psi pre-filter. Through the filter was close to 12psi when checked by a banjo bolt. I have friends pushing more than 17psi inlet on the 6bt and the seals are holding fine. In fact, we notice more top end fueling and less smoke in the higher RPM range.

So how does the VW VE differ from the Cummins VE?
 

VWBeamer

Veteran Member
Joined
Jan 1, 2009
Location
GA
TDI
2004 Jetta Wagon
have you checked the Johnson Rod? If not, I would bottom it out, then screw it out one turn.
 

VWBeamer

Veteran Member
Joined
Jan 1, 2009
Location
GA
TDI
2004 Jetta Wagon
Seriously, the VW VE motor has no PSI at the IP, but you certainly can add an electric pump pre filter.

The common MOD is to add the pickup pump from a later model PD VW TDi.

I'm not sure how much PSI you can run, I'm guessing 12 PSI or so.
 

jhaas88

Active member
Joined
May 21, 2010
Location
IL
TDI
Looking
I am talking about fuel pressures at the inlet, post filter.

All I see is "Don't run more than 2-6psi". I am asking WHY no more than that?
 

vwmikel

Vendor , w/Business number
Joined
May 5, 2005
Location
Las Vegas, NV
TDI
'94 Golf Sport TDI
I am talking about fuel pressures at the inlet, post filter.

All I see is "Don't run more than 2-6psi". I am asking WHY no more than that?
The system wasn't designed to be pressurized so things start to leak. That said, there have been people who've run unregulated gas in-tank pumps and I hadn't heard of any failures from that...regardless of how little sense it makes.
 
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