arjax
Veteran Member
I have a 01 C5 BHW swapped allroad that I am contemplating replacing with 3L TDI V6. I wanted to see which year of the 3L would be the best candidate for the swap. Thoughts?
TIA
TIA
Which 3l v6 TDI for a C5 allroad swap?
- Thread starter arjax
- Start date
oilhammer
Certified Volkswagen Nut & Vendor
I'd keep the BHW.
The 3.0L V6 as used in the later longitudinal cars (A6, A7, A8, Q5) would be the closest thing, but those later chassis are VERY different. The whole way the engine/trans mounts is completely different, the steering setup is completely different, they have a removable firewall (like a mini dog house on a domestic van sort of) so I think you'd have a lot of fabrication work to do. And the transmissions they use are different, as the axle centerline is right up next to the end of the crankshaft. The DMF or TC is BEHIND the axle.
The V6 TDI that was available in that era platform is the 2.5L, and they are not a very good engine according to folks in Europe that actually had a choice to buy them (they'd also tell you to stick with a 4 cyl).
I'd say you need to get underneath one of the above mentioned cars, and poke around to see how it is all arranged. Not saying it could not be done, it just may be a lot of work.
The 3.0L V6 as used in the later longitudinal cars (A6, A7, A8, Q5) would be the closest thing, but those later chassis are VERY different. The whole way the engine/trans mounts is completely different, the steering setup is completely different, they have a removable firewall (like a mini dog house on a domestic van sort of) so I think you'd have a lot of fabrication work to do. And the transmissions they use are different, as the axle centerline is right up next to the end of the crankshaft. The DMF or TC is BEHIND the axle.
The V6 TDI that was available in that era platform is the 2.5L, and they are not a very good engine according to folks in Europe that actually had a choice to buy them (they'd also tell you to stick with a 4 cyl).
I'd say you need to get underneath one of the above mentioned cars, and poke around to see how it is all arranged. Not saying it could not be done, it just may be a lot of work.
Yeah but there is something to be said for the smoothness and sound of a V6. (Says the guy who is pulling out all the stops to bring home a V6 car that seems to be having at least some of their typical issues.... 
)
@arjax, as OH said above the Euro spec 2.5L V6 TDI engine is known for having some trouble areas (injection pump and valvetrain primarily). But its advantage (though I realize this is not the answer to the question you asked) is that in other markets it was available as a factory option in the C5 cars. So if you wish to go to a 6cyl they are the most obvious path. No reinventing the wheel in terms of electronics, fitment, plumbing, transmission interface, etc. Can't say what exactly those aspects would look like with the 3.0L to a C5 but it is a safe assumption that they would be much more challenging, presumably solvable with enough skill and effort and funds but not easy.
The 2.5L engine's downsides, aside from those couple common problems, is of course acquiring one in N America, and then sourcing parts from overseas to keep it going. But to me those are livable downsides for a car that is not my primary vehicle and thus it is the path I am taking with my '01 C5 allroad. I do know of a couple more 2.5 engines with harnesses that are available if you are going to look into that route and want to PM me.
Plus of course the old 2.5L is smaller displacement and much more primitive technology than the modern common rail 3.0L engines we got in the US, and the 3.0L's power and torque figures simply stomp all over the 2.5's. And you get US dealer parts support from VWoA on the 3.0. But again, for any of those factors to even matter at all in a practical sense, you'd have to be able to successfully install and integrate it in the C5 car. No small challenge. I think Scott DeWitt on here tried a swap with a 3.0 in an allroad years ago, and to my memory, he did find a clutch/flywheel recipe that went together OK and managed to get the engine sitting in the car. But his thread eventually petered out and my suspicion is the swap never reached the road due to trouble with the details.
Oh yeah, the other downside to the 3.0L of course is that it is extremely complex and has timing chain issues, can have the usual CR fuel system failures, etc. The 2.5L V6 is a belt motor with an old school rotary injection pump that does not suffer those.
)@arjax, as OH said above the Euro spec 2.5L V6 TDI engine is known for having some trouble areas (injection pump and valvetrain primarily). But its advantage (though I realize this is not the answer to the question you asked) is that in other markets it was available as a factory option in the C5 cars. So if you wish to go to a 6cyl they are the most obvious path. No reinventing the wheel in terms of electronics, fitment, plumbing, transmission interface, etc. Can't say what exactly those aspects would look like with the 3.0L to a C5 but it is a safe assumption that they would be much more challenging, presumably solvable with enough skill and effort and funds but not easy.
The 2.5L engine's downsides, aside from those couple common problems, is of course acquiring one in N America, and then sourcing parts from overseas to keep it going. But to me those are livable downsides for a car that is not my primary vehicle and thus it is the path I am taking with my '01 C5 allroad. I do know of a couple more 2.5 engines with harnesses that are available if you are going to look into that route and want to PM me.
Plus of course the old 2.5L is smaller displacement and much more primitive technology than the modern common rail 3.0L engines we got in the US, and the 3.0L's power and torque figures simply stomp all over the 2.5's. And you get US dealer parts support from VWoA on the 3.0. But again, for any of those factors to even matter at all in a practical sense, you'd have to be able to successfully install and integrate it in the C5 car. No small challenge. I think Scott DeWitt on here tried a swap with a 3.0 in an allroad years ago, and to my memory, he did find a clutch/flywheel recipe that went together OK and managed to get the engine sitting in the car. But his thread eventually petered out and my suspicion is the swap never reached the road due to trouble with the details.
Oh yeah, the other downside to the 3.0L of course is that it is extremely complex and has timing chain issues, can have the usual CR fuel system failures, etc. The 2.5L V6 is a belt motor with an old school rotary injection pump that does not suffer those.
BTW, for whatever it's worth, from having done a lot of reading about it, I think most of the negative opinions that are seen from Europe about the 2.5L V6 are really mostly not about concerns on the engine's soundness. They are more based around complaints that it is not as "tuneable" as the 4-banger families are. In the sense that it is not as simple to access tons of cheap or free extra power and double the HP rating, taking a 90hp engine to 200hp as one can with the ALH and PD motors without great effort or cost. They complain that it is heavier and more complicated than the 1.9 yet not any faster than a 1.9 with a tune and gets a few MPG less. In particular the injection pump on the V6 has internal software that inhibits the options for pouring massive increased amount of fuel into the motor like one can with a simple swap to 11mm pump and big nozzles on an ALH, for example. And evidently the intake ports on the V6 eventually also become a restriction for those chasing massive dyno numbers.
In other words when they say "2.5 is a POS boat anchor" they mostly mean they encountered roadblocks when they tried to hot-rod and did not find the stock or near-stock performance to meet their expectations, relative to what they had grown accustomed to from the 4cyl TDI engines.
But to me those folks are missing the point, it's meant to be a more refined diesel option above all else, with a moderate increase in power and smoothness over an equivalent era 4cyl diesel. Not ever intended as a rocket powerhouse like a 2.7TT or RS6. In a big heavy car like a C5 allroad an extra 150lb from a larger engine under the hood is not that important. They may be more challenging to turn up the power on, but if you plan to enjoy it as the stock 150-180hp as it is or do a little mild tuning, they seem to work great in that realm.
The issues with the VP44 injection pump (also used on 24 valve Cummins and other diesels) have been solved over time by and large, and the V6 2.5L's reputation for valvetrain trouble seems to mostly be traceable to neglect of oil changes plus on the later series motors they added a roller valvetrain that made it a non-issue. So to the extent there are any actual problem areas they are manageable to the point that they don't really matter. Certainly no more than cams and lifters in PD engines are an issue anymore. Like on those, we know how to deal with it and live with it and it doesn't change the fact that they are good motors.
On that note, yes the simplest option of all is of course to keep enjoying the BHW you already have. I decided against a BHW swap in my 2.7 allroad and went in favor of the diesel V6 instead given that I'm starting with a blank canvas, but if I already had a BHW swapped allroad that was finished and working well, it would be hard to want to change away from it I think.
In other words when they say "2.5 is a POS boat anchor" they mostly mean they encountered roadblocks when they tried to hot-rod and did not find the stock or near-stock performance to meet their expectations, relative to what they had grown accustomed to from the 4cyl TDI engines.
But to me those folks are missing the point, it's meant to be a more refined diesel option above all else, with a moderate increase in power and smoothness over an equivalent era 4cyl diesel. Not ever intended as a rocket powerhouse like a 2.7TT or RS6. In a big heavy car like a C5 allroad an extra 150lb from a larger engine under the hood is not that important. They may be more challenging to turn up the power on, but if you plan to enjoy it as the stock 150-180hp as it is or do a little mild tuning, they seem to work great in that realm.
The issues with the VP44 injection pump (also used on 24 valve Cummins and other diesels) have been solved over time by and large, and the V6 2.5L's reputation for valvetrain trouble seems to mostly be traceable to neglect of oil changes plus on the later series motors they added a roller valvetrain that made it a non-issue. So to the extent there are any actual problem areas they are manageable to the point that they don't really matter. Certainly no more than cams and lifters in PD engines are an issue anymore. Like on those, we know how to deal with it and live with it and it doesn't change the fact that they are good motors.
On that note, yes the simplest option of all is of course to keep enjoying the BHW you already have. I decided against a BHW swap in my 2.7 allroad and went in favor of the diesel V6 instead given that I'm starting with a blank canvas, but if I already had a BHW swapped allroad that was finished and working well, it would be hard to want to change away from it I think.
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oilhammer
Certified Volkswagen Nut & Vendor
90 degree V6s are not "smooth", that's why they have to get balance shafts. Just sayin'. (60 degree V6s and inline 6 and flat 6 are not saddled with that issue). Even the 3.0L V6, at idle, there is no mistaking it is a diesel. MB did a better job with that part. A commercial van (Sprinter) has a more refined feeling V6 engine than a luxo-barge Audi sedan does, honestly. But, VAG's 3.0L does have a boatload of power, and it is well matched to the 8sp ZF they use. Having recently worked on one, though, I'm not as impressed as I was before. Too complex, too fragile, too many tiny little expensive bits and each one takes a month to get. And once again, the use of plastic engine parts buried in the engine is a leaky liability.
True. 90deg V6 is not the most elegant engineering compromise. Balance shafts and split crankpins are probably not what God intended. 60 degree or 180 degree sixes do for sure make more sense. And all else equal I personally would take a boxer engine or better yet an inline six or 90deg V8 over almost anything else in terms of elegant simplicity and balance.
But those don't fit in every engine bay and are often heavier. And in defense of 90deg V6 engines, at least as I understand the theory, they can sit lower under the hood than a 60deg vee engine can with a wider bank spread, have more room in the valley for things like injection pumps and turbos (which the 2.5 engine takes advantage of).
And no matter what bank angle you have you still get 6 power pulses every 2 revs instead of 4. So even if the mechanical thrash with a 90deg motor is not as optimal, the vibes through the driveline(s) are less severe.
A well engineered 90deg V6 seems like it can hang in there NVH-wise. I had a late '80s Volvo with the late series aluminum PRV 90deg 2.8L V6 and that engine was smooth as glass even without a balance shaft. And of course Audi's 2.7, 2.8, 3.0, 3.2 gassers are all very nice motors to live with. Even GM's and Ford's old 90deg 3.8L engines with their balance shafts ain't bad in the cars I have tried with those. Certainly not as smooth as a BMW inline six or Toyota 60deg V6 but still smoother than any 4-banger.
I don't disagree with you by any stretch though.... in theory, it's not an ideal solution. I will be curious to find out what the 2.5L feels like firsthand when I get hands on a running one in a couple weeks here.
Wasn't MB's V6 a 72deg motor? Hard to understand that, seems like the worst of all worlds in terms of manufacturing efficiency and mechanical balance and complexity.... I guess packaging must have been their main consideration.
But those don't fit in every engine bay and are often heavier. And in defense of 90deg V6 engines, at least as I understand the theory, they can sit lower under the hood than a 60deg vee engine can with a wider bank spread, have more room in the valley for things like injection pumps and turbos (which the 2.5 engine takes advantage of).
And no matter what bank angle you have you still get 6 power pulses every 2 revs instead of 4. So even if the mechanical thrash with a 90deg motor is not as optimal, the vibes through the driveline(s) are less severe.
A well engineered 90deg V6 seems like it can hang in there NVH-wise. I had a late '80s Volvo with the late series aluminum PRV 90deg 2.8L V6 and that engine was smooth as glass even without a balance shaft. And of course Audi's 2.7, 2.8, 3.0, 3.2 gassers are all very nice motors to live with. Even GM's and Ford's old 90deg 3.8L engines with their balance shafts ain't bad in the cars I have tried with those. Certainly not as smooth as a BMW inline six or Toyota 60deg V6 but still smoother than any 4-banger.
I don't disagree with you by any stretch though.... in theory, it's not an ideal solution. I will be curious to find out what the 2.5L feels like firsthand when I get hands on a running one in a couple weeks here.
Wasn't MB's V6 a 72deg motor? Hard to understand that, seems like the worst of all worlds in terms of manufacturing efficiency and mechanical balance and complexity.... I guess packaging must have been their main consideration.
oilhammer
Certified Volkswagen Nut & Vendor
Yeah, they are 72 degrees. Still have a balance shaft, though.
arjax
Veteran Member
Thanks for the input. You're probably right @oilhammer about just sticking with the BHW. I am running at Malone Stage 2 but it still feels underpowered. I haven't upgrade the turbo so I am not sure if that would help being that I am running 6spd 3.89 final drive setup (6th gear it about 1900rpm for 60mph) or if the transmission setup is the problem. I have been a little frustrated with the car but I think I am trying to solve problem(s) that I just don't have the car acumen to know why it's having an issue.
Compared to what?
What do you use this car for and what situations does it feel slow in? Stoplight acceleration in town? Quarter mile runs? Freeway commuting? Maintaining 80mph when fully loaded plus stuff on the roof and towing a big heavy trailer into a headwind climbing a mountain pass on a 110 degree day at high altitude with the AC on?
A little more context will help the rest of us determine if it's an actual engine or configuration issue that is solvable, vs a problem of expectations. Don't forget this is a little engine in a big heavy car turning four big tires and five driveshafts.
"Upgrades" to the BHW engine in terms of tune, turbo, fuel might be risky depending on what your intended use is and in what operating situations you are wishing for more juice. This would be where IMHO your original idea of running a larger displacement motor might be logical, if the goal is to add power you could use in a sustained continuous way.
arjax
Veteran Member
No doubt...sometimes I forget what's being asked of this little engine. The "underpowered" comment was ambiguous and you're probably correct that it is more a problem of expectation. Last night the car died while just cruising home at about 45 mph. It's looking like a timing issue as I have code for the cam position sensor (CamPS) being out of range p3008. When the CamPS is plugged in the car won't start. I had pulled the glow plugs to see if fuel was being injected and it wasn't. When I unplug the CamPS, then fuel started to be blown out the glow plugs holes. It now starts but it runs rough and dies every time about 5-6 after firing up (I tried to raise revs and then kills). So I am hoping it is just a bad sensor. If it is, it might explain why the fuel economy over the last little bit has been down and even some of the feeling of being underpowered.
Code:
19464 - Camshaft Position Sensor (G40)
P3008 - 000 - Signal Out of Range
Freeze Frame:
RPM: 1764 /min
Torque: 86.0 Nm
Speed: 46.0 km/h
Load: 25.1 %
Voltage: 13.83 V
Bin. Bits: 00001000
Idle Stabilization: 0.0°KW
(no units): 35.0
PickleRick
Veteran Member
- Joined
- Nov 29, 2017
- Location
- Greenville sc
- TDI
- 05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
Have you looked into a bv43 turbo upgrade? Supposed to pack a little more punch without internal upgrades.
arjax
Veteran Member
I have seen that's an option and read some about it. Looks like some were using a BV43a CHRA. Have you use the bv43 in any of your BHW @PickleRick ? If so, any thoughts on it?
PickleRick
Veteran Member
- Joined
- Nov 29, 2017
- Location
- Greenville sc
- TDI
- 05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
I have not, there are several active members that frequently lurk in the b5 forms that do. About all I know is it's a more robust turbo and requires a reflash on your tune. My rig weighs a lot and had some big tires, I'm afraid of wasting a bunch of cash to install a turbo that has too much lag. Most of my daily commute is city traffic.