So I am at the stage of starting to tackle the big problems with my 72 Devon. I have stripped out the interior again and need to do various bits of welding and other things to get it ready for use in the summer. One of the big things is redoing the pop top. Another is sorting the engine. After buying my van a year and a half ago with a 'recon' engine, it died very quickly due to a badly corroded case. I therefore bought a second hand 1600cc long block and transfered all the ancillaries to that so that I was still able to use the van. The current engine is a gutless, leaks oil and the compression is not great. I have spent the last few days reading lots of threads on here, other forums and the pages on John Maher Racing website. I have deduced from all this that the sensible thing to do is to build a 1776cc stroker engine using a new Auto Linea case. I just want to build a good reliable engine that will not cost a fortune. I am able to use some parts from my engine that has a damaged case (I discovered the case leak before the oil all came out so the engine was not damaged from lack of oil etc). If necessary I can also take my current running engine out and use parts from that. So the prevailing opinion seems to be that a 1776 stroker engine is the best solution for a bus. I am going to buy a new machined case and stroker crank. I have acquired a 36 DRLA carb setup already, I have a 123 ignition. Since the case and crank will be new I don't know what other components ought to be new. I am not sure about heads, cam etc what spec and whether new or from my two donor engines. Online I came across the book Volkswagen air-cooled engine rebuild manual: stripping, inspecting and rebuilding VW air-cooled engines by Laurie Pettit. I thought this would be ideal to help me learn and carry out the build of the engine I am planning. However, no where seems to have it available. I have contacted Haynes publishing and I'm waiting to hear back from them. Does anybody know if this book is still available anywhere or has a copy for sale or why production ceased? Does anybody have any advice on how to spec the rest of the engine and whether I ought to use new or used parts? I have the time and workshop facilities to carry out the build. I know it is a lot to learn but I would like to do it for my own understanding of fixing things in the future or doing work on the engine in the future.
Laurie’s book never made it to publication I’m afraid For 1776 you don’t need a stroker crank just the case and heads machining to accept larger barrels.
^this. Stick with a straight 1776. Ignore most advice in the books. Most of it is bad/useless. Avoid anything chrome.
From all the threads and the project 2110cc build on John Maher's website it says it is all about torque and the 82mm stroke crank and 90.5mm b&p is a safe and good way of increasing capacity if you are going to change the case anyway. Is there a disadvantage to stroker motors. I know it doesn't have to be done but it seemed like a good opportunity especially when I read the information on John Maher's website. What am I missing?
There is so much to building a stroker - especially with an 82 mm crank. Case clearance for crank and cam Cylinder head choice Rod length Valve springs Push rod length Exhaust choice Cylinder length Piston gudgeon pin location Carburettor / injection set up it is not going to be cheap - if you want it to last Not something I would practice on have a read here https://www.aircooled.net/vw-performance-engines/
JMR and aircooled.net are both good sources of information but are mostly related to engines for racing and car use. For a heavy bus you need torque and while it is a fact that the larger the engine the more torque it will make, with a Type 1 heat is the limiting factor. And the more capacity the engine has the more heat it will produce. If you just want to build a good reliable engine that will not cost a fortune, keep it simple, especially if this is your first non-standard engine build. 1776cc is an easy upgrade but needs the case and heads to be machined, a stroker engine has more potential problems to consider, as Barry listed. And more than 1776cc probably makes more heat than the cooling system can cope with. For a bus use a cam that makes power in the rev range you normally use, avoid heads with big valves and don’t use a lightened flywheel.
Yes. Heat that cannot be removed by the stock cooling system if you drive it hard for long distances. Because its more powerful you tend to go faster and parts get hotter. When VW went from 50HP to 70HP engines they uprated the cooling fan from 650CFM on a T1 (top speed about 70mph) style to 800CFM on a T4 style (top speed 79mph) to match. The 1776 which uses the original forged crank 69mm stroke and is just machined for larger pistons and cylinders is regarded as a reliable size. The Autolinea aluminium cases seem to make sense from the viewpoint of being new so not needing align bore machining to compensate for the warping and wear on 50 plus year old original engine cases. Go bigger and more power means more heat which can mean valve seat problems on a T1 based engine where the aircooling is set up for a 1600.. You could be spending a lot of money only to end up with a less long lived and reliable engine. Heat increases on my bus rapidly above 65mph on the GPS or 70mph on the speedo.
The problem with ‘big valves’ is the reduced port velocity at low revs; but the 1800 type 4 ‘S’ heads don’t have particularly large valves, just bigger than the very small valves VW fitted to the 1700 and 2.0l engines.
Does anyone know at what point of increased stroke Means a stock exhaust and inlet won’t fit a type one engine?
Not a simple answer. Exhaust depends on cylinder length, as that is a variable. A lot of performance exhausts are adjustable or custom. Inlet is normally not a factor as dual carbs negates the problem. But guessing there are issues after a 74 crank
Because cylinders are all approximately the same length and you want your tinware to fit the overall width of the engine stays within a couple of mm of stock so everything fits. The process is working out how far your crank will push the piston up the barrel, then working out which combo of piston pin height and rod length gets you closest to 1.2-1.5mm deck. Err on the "piston too far up the barrel" side and you can shim under the barrels. When I built my 76 x 92 engine I used B pistons, slightly longer conrods and a small shim under the barrels. IIRC there is an odd sized crank(74.5?) than works out with stock rods but I had that wasser 76mm crank. To back up some opinions on cooling, this is the frustration of big type-1 engines in buses - you can build an engine to accelerate but not to cruise faster than stock. At that point if you're like me you convert to a type-4 engine.
Its just I’ve seen lots of posts on various forums over the years where people are having trouble getting tinware and exhausts etc to fit properly and also having push rod length and rocker geometry problems after using a longer stroke crank. There must be a sweet spot somewhere where only minimal adaptations are needed. My case has been machined to take the larger barrels to make it 1776 (90.5?) Im wondering by using stroker pistons and a longer stroke crank can the capacity of the engine be increased to around 2 litres whilst still having a stock exhaust and inlet manifold. Im fully aware of the cooling limitations and I’m not looking to drive long runs at 70 mph However a good dose of torque to aid in climbing inclines for short periods would be beneficial
76 x 92 = 2020cc 76 x 90.5 = 1955cc Now your problem will be how to loose the increased CR so you can use a low rev power band cam. 69 x 94 = 1915 - stock crank, stock rods.
So if you were to build a large capacity type one again would you go for the larger barrels rather than a longer stroke Like your type four? I think at 90.5 it’s machined just on the edge of the case savers so anything larger will be cutting into them.
I think they all use the same holes, I swapped out 90.5 for 92. There's sense to me in 69 x 90.5 or 92. It's cheap and stays just the right side of the myriad of problems of larger engines which could entail new exhaust, con rods, heads, carbs as well as the problems of CR, just to end up with a powerful engine you have to drive bellow it's capabilities because of the heat generated. Just my opinion. Personally what always pee'd me off was the lack of increased cruising speed. The engine wanted to do it but I couldn't let it.
So that all these sizes fit the same machining, the walls get thinner as the size increases - made from the same cast. Or that used to be the case. IDK about 94mm but 92mm ones are now made from a different cast with thicker walls, but still the same outer dia where it fits in the case. As far as short v long stroke, as you're not making a revver I doubt it would be much different to drive. We're only talking a few more mm stroke on top of almost 70mm. I think the reason to stroke is smaller barrels and pistons burn better so get your cc from stroke. My 104mm pistons do not burn well, it's slow and needs extra timing. At what size it starts to get noticeably worse IDK.
I believe there use to be 3 types of 92’s thin walled slip ins Thick walled slip in with thin at the base Old school thick wall machine in not sure what is available these days. The old school thick walls were popular in busses can’t find thin walled slip ins for sale. Only machine in. Case and heads need to be cut as for 94’s
