VW engine conversions in the UK

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ivan tanner
Posts: 2
Joined: Mon Sep 18, 2023 4:48 pm

VW engine conversions in the UK

Post by ivan tanner » Mon Sep 18, 2023 4:54 pm

Hi All,
Has anyone had any recent experience please with any companies who build/rebuild VW engines ? I'm looking for a new/recon'd 2100cc for my project and would ideally like to source within the UK if possible. I have found lots of VW engine specialists online but would hope to deal with someone who understands the needs of an LAA type, rather than providing me with a 200hp dragster engine.
Many thanks,

Hap Hazard
Posts: 5
Joined: Sat Apr 07, 2018 8:55 pm

Re: VW engine conversions in the UK

Post by Hap Hazard » Thu Dec 21, 2023 2:35 pm

Hi Ivan,
I don’t know how far you’ve got with your VW project, but for what it’s worth, here’s my 2-penth’s worth….
Firstly, if building from scratch, then you open Pandora’s box because there is so much choice with the VW after-market world. If you are looking to source and build your own engine, then you really need to start with those that know their beans (read not me!).
For me personally, probably the best VW based Aero engine out there in terms of all round design is without doubt, Revmaster. For the Eagle-eyed, Revmaster also covers the points others often fail to appreciate fully, for instance their understanding the need for proper micro oil filtration and its affect on longer-term engine life and hence ‘reliability’ (a word that every self-respecting aviator should love).
Take careful note of the principle dimensions (read bore and stroke, etc) that the 3 main VW builders do, that is Revmaster, Aerovee (Sonex), and Great Planes. Things like rod ratios, stroke and bore size is important, so don’t start chucking just anything in the case, because you want to get the best out of the engine for the RPM we are typically limited to.
I won’t give you a full run-down of my thoughts here but my advice is, if you can locate a used Aerovee or early Revmaster, then that’s a good starting point as basically you get the rear accessories housings for ignition systems, starter (in some cases) and generator etc. Also the crank is important (very, especially as the crank is the “spine” of your motor), so again a decent forged crank is a MUST and needs to have the correct stroke. If you’re using std cases, they will need some serious clearancing (and be aware of the differences in cases over the years).
If you are looking to get a company to build on your behalf, then your going to need to be able to advise them in many ways, as they will be focused on the other end of the Rev range for entirely different reasons, so a top quality race shop is going to need a lot of nudging and our world does things they would have never encountered before, for instance, using the fan pulley end as the primary source of drive! Also appreciate, the VW is not Air-Cooled, oil also performs a vital role in cooling this motor too. With the Type 1 it’s Achilles heal being poor cooling of the heads (the type 4 heads were far superior). Also be VERY wary about Bob Hoover info. Much of what he said was good sound info but don’t be fooled by all that he says, especially his blogs on the Hoover mods, you will potentially bugger up your engine if you follow ALL of his recommendations and start shoving more oil into the heads, because now you’re getting less oil going to where it counts most, your big end bearings.
Most competent VW specialist shops in the UK where Bug enthusiast spend £££ in doing up race motors will be able to do the work you need, but they will need guidance in terms of our weird bits and needs of how and where we operate the engine at all day long and weird stuff like the prop hub etc. For general case clearancing work, line boring and boring out heads and case for stroker pistons, should be run-of-the-mill stuff to them.
The combo in terms of rods, cranks, pistons, cams, rockers, (even humble rocker covers) is going to be largely down to your knowledge and as I said, following the basic format of what the established commercial builders in the States typically do. They have developed their products over years of trail and error and have come to a fairly refined product. Remember, your enemy is 1001 experts on forums and a huge range of after-market spares in the VW engine world, all of it of varying quality and tolerances.
If you want a more comprehensive missive from me on MY opinion and what my approach would be, then PM me but if you are self-building a VW based motor, ground up, you need to have a good understanding of the engine, understand the value of the original VW design engineers (they did know a thing or two) and be very wary about all you read on forums! Remember, the basics of any engine and efficiency/reliability starts with building a motor to within factory tolerances, so understand the benefits of a properly set-up and “balanced” engine….
There is a lot in there, but once you get a basic format together, then you will make positive progress to a reliable motor but it ain’t like many of us expect, you won’t just be able buy and bolt to together and expect it to do miracles…it needs to be engined from one end to the other…..

Posts: 139
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Re: VW engine conversions in the UK

Post by TRAZZELL » Thu Dec 28, 2023 6:10 pm

I think it would be good to have an area on the LAA Engineering pages to hold pooled knowledge/best practice for VW builders and operators. If there was some oversight/moderation by LAA Engineering, we could be more confident on the quality of the information than if it was off some forum or other. What are peoples thoughts on that idea (particularly from LAA Engineering)?

Tony Razzell
Tony Razzell

ivan tanner
Posts: 2
Joined: Mon Sep 18, 2023 4:48 pm

Re: VW engine conversions in the UK

Post by ivan tanner » Fri Apr 12, 2024 5:13 pm

Hi H,
Many thanks for those details, and sorry for not replying sooner. My day job has kept me busy all winter.
All you've said makes perfect sense, I have had limited contact with engineering about this and fully support Tony's views about being able to put views into the forum with oversight/comment from them. Interesting to note they haven't had a chance to reply yet.
I was recently able to have a chat with an extremely experienced, talented and helpful engineer (thanks DB if you see this !) who echoed your thoughts on the Revmaster. He pointed me toward one available S/H, low hours, for about 5,500. I'd still like to use something new though, and since it looks like Great Plains are marketing kits again, that would be my current preferred choice (comparing like for like as far as possible, they look thousands cheaper than the AeroVee).
Also, I gained a bit more of an understanding about the "Conversion", again echoeing your points, well received.
I just purchased a copy of Rex Taylor's 1979 so will study further, but if you do have any thoughts on the Great Plains I'd be all ears.
Have a nice weekend,

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