I have an '04 Itasca Sunstar 21-ft motorhome on a '03 VW Eurovan platform with the 201-hp VR6 engine.
Altogether, the 2.8-ltr, 24-valve V-6 is moving 7,250 pounds in it's current motorhome RV configuration.
Coupled with a 4-speed automatic transmission, the entire vehicle drives on level freeways easily and able to attain speeds a little over 80 mph.
However, subject the vehicle to an uphill climb and it's struggles to a crawl. Fortunately, engine temperature doesn't rise over 1/2 on the temp guage while "hunting" between 3rd & 2nd gear. It's also a good thing that I don't have to pull a trailer behind me.
Bottomline is that my 181 lb.-ft. of torque is not enough. My VR6 engine NEEDS MORE TORQUE.
I considered employing a turbocharger to add more power and boost fuel economy but the Eurovan's engine bay isn't spacious enough to accommodate all the necessary components. So, I guess that's out (unless a new remedy is suggested).
How about headers to replace the stock exhaust manifolds? Any objections or recommendations?
What about a computer chip upgrade? Is that even possible?
Last but not the least, will a supercharger work? Is there even a supercharger that can be matched with the VW VR6? If yes, where can I acquire it?
Sensible suggestions/recommendations will be much appreciated.
I don't think a 1.8T swap makes sense. There are turbo swaps out there for the 24v VR6 that are going to get you more HP/torque.
It sounds like a lot of your issue is the transmission. Which is going to be an issue in any swap you do as well. If you swap for a 1.8T you aren't going to want to keep the stock 01P 4 speed automatic.
The transmission is unfortunately the weak point in these vans.
You basically have a few options:
1) Keep the VR6 and get an 02G 5 speed (EU spec 5 speed transmission) and swap to a manual transmission.
2) Do an 02G 5 speed swap and add a turbo to the VR6.
3) Do an 02B 5 speed swap (like in the US spec manual Eurovans) and a motor swap to something like a TDI or 1.8T
None of these options are particularly cheap. If you're going the work yourself you could do a TDI swap for a maybe 2-3k, depending on parts you source and how much you get when you sell your old engine/transmission.
There aren't any great automatic swaps in the Eurovan that have been done.
Adding a turbo to the 24v VR6 is going to grenade that transmission.
I agree that putting more torque and HP to the 01P auto trans is dangerous, since it's a pretty fragile transmission.
If you're dead set on a more powerful VR6 though, a manual swap would be in order. For VR6 donors, I'm not entirely sure what the compatibility is, but what comes to mind for "bigger" is the 3.2 VR6 from a Mk4 Golf R32 or from a first-gen Touareg. Yeah the Touareg was a longitudinal mounting IIRC and not transverse, but isn't it the same VR6 anyway? There also were 3.6L VR6s in later T-regs and also in the Passat. IDK if those are too far "distant" from the T4 to bolt in though, but if they do, that'd widen your donor search.
Going a TDI + manual swap is a good idea as well for the fuel economy, as bigger VR6s will just eat more fuel. It won't be a drag racer with a TDI, but the torque and the low-end should be good for maintaining speed on hills and towing.
Best option is to sell it and get something else. From looking at your post, you are not the DIY type person where you'd undergo a major project. Every suggestion is for a tinkerer not someone looking to add bolt on power. Everything everyone suggested is completely wrong for you in the situation you are in. Even though I'm a tinkerer, mechanical engineer and have tons of motorsports experience, I went ahead and bought a Class C RV that has a Ford V10 in it. Why? You can't shoehorn anything in that Eurovan that will give reliable performance like I have. My class C is a 26ft. The engine and trans just cruise along with no struggle at all. I can't imagine punishing my Eurovan engine and transmission with all of that extra weight. I even put cams in my Eurovan.
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