Toying with the idea of a larger engine

[milfredo]

I am thinking of slowly collecting parts and building a larger engine. I done a fair few engines before but only for Type Threes and there are a lot of little things you need to take onboard to get them to fit nicely (cross brace, short manifolds, drilled case for dip-stick location etc) and I was wondering what needs to be thought of for a 71 Bus.

One thing that was bothering me is where would you take the feed for the break servo? As silly as this may sound!

 

[ozziedog]

Inlet manifolds just the same. The diesel styled pump route is also an option.

Ozziedog,,,,,,,,,,, possibly a balance pipe ?

 

[K@rlos]

What sort of ‘big engine’ are you looking at? A nice smooth torquey cruiser or a high revving traffic light / 1/4 mile terror?

As ozzy says the inlet manifold for the vac take off, just be aware an engine with a rowdy camshaft which has a lot of overlap causes exhaust gas reversion and affects cylinder filling at idle and low speed. Poor vacuum is side effect of this so a remote vacuum pump may be required if you go that route.

The 2 areas people normally struggle with when putting a performance engine in a bay is the oil system and the exhaust due to the rear engine bar. I’ve put a lot of big engines of various flavours in 68-71 buses including my own nitrous 2276 so if you have any questions feel free to pm me

 

[CleoMar]

I went with an upgrade on my existing 1600 dual port motor to a 1776cc. Fairly simple upgrade and gives me adequate power. Perhaps 85bhp. Added a drop sump which increase capacity to 4 liters coupled with an external oil filter. Added larger fan but am going back to the original cooling fan. Cooling is good. Using two Weber IDF 40's with 28 venturis. vacuum for braking servo is taken from both fuel input manifolds which needed to be adapted for the purpose. Again a fairly easy fix. Rebuilt the original 3 rib trans to a "freeway flyer" spec with higher 4th gearing to reduce revs on the highway. Uprated valve springs plus I added a heavy duty clutch which in retrospect is not necessary given my driving style. Kept the compression around 7.5. Very happy with the outcome. I wanted reliability and good engine life. Could not see the advantage of going extreme since engine life is likely compromised and after all we are still driving a "brick".

 

[milfredo]

I would be in the 1776 to 2100 range... I would like to keep things like heat exchangers (I like everything working). Not looking for revs or massive cam as I wasn't to be able to pootle everywhere but have more movement on the motorway when fully loaded with the family. Remote oil filter and maybe a cooler if needed. Bus is too low for a deep sump and I would like to keep my vintage speed exhaust which is 38mm I think. Duel carbs, not too fussed on four chokes if not needed.

@CleoMar who built your engine? I'm also toying with buying the bottom end complete.

 

[K@rlos]

I would be in the 1776 to 2100 range... I would like to keep things like heat exchangers (I like everything working). Not looking for revs or massive cam as I wasn't to be able to pootle everywhere but have more movement on the motorway when fully loaded with the family. Remote oil filter and maybe a cooler if needed. Bus is too low for a deep sump and I would like to keep my vintage speed exhaust which is 38mm I think. Duel carbs, not too fussed on four chokes if not needed.

@CleoMar who built your engine? I'm also toying with buying the bottom end complete.

In that case I’d go along the lines of a 2007cc stroker, 8-8.5:1 compression, twin 40’s, sensible heads which are lightly ported, possibly with 40x35.5 valves and an Engle fk7 cam with 1.4 rockers. That cam will give it plenty grunt straight off idle and cruising but be done by 5000rpm. 26mm oil pump, remote filter and a decent oil cooler fed off a thermostatic sandwich plate. Will be a nice mile muncher.

But, as with all things it depends on budget.

 

[sparkywig]

I ran a 2054 in the sow's ear for the last 12 years.
74x94, C35 cam, match ported heads. 125bhp/160lb/ft, plenty of grunt for cruising/towing and the odd blast around Spa.
You won't need a deep sump unless you've got a massive stroker crank.

 

[milfredo]

Thanks chaps, brilliant stuff! Could I keep stock 38mm exhaust with a 2007?

 

[K@rlos]

Thanks chaps, brilliant stuff! Could I keep stock 38mm exhaust with a 2007?

Yeah a 38mm exhaust will be fine, you’re not looking for massive rpm and a smaller diameter exhaust will be more favourable for grunt.

 

[milfredo]

Nice one!

 

[CleoMar]

In that case I’d go along the lines of a 2007cc stroker, 8-8.5:1 compression, twin 40’s, sensible heads which are lightly ported, possibly with 40x35.5 valves and an Engle fk7 cam with 1.4 rockers. That cam will give it plenty grunt straight off idle and cruising but be done by 5000rpm. 26mm oil pump, remote filter and a decent oil cooler fed off a thermostatic sandwich plate. Will be a nice mile muncher.

But, as with all things it depends on budget.

I would be in the 1776 to 2100 range... I would like to keep things like heat exchangers (I like everything working). Not looking for revs or massive cam as I wasn't to be able to pootle everywhere but have more movement on the motorway when fully loaded with the family. Remote oil filter and maybe a cooler if needed. Bus is too low for a deep sump and I would like to keep my vintage speed exhaust which is 38mm I think. Duel carbs, not too fussed on four chokes if not needed.

@CleoMar who built your engine? I'm also toying with buying the bottom end complete.

I am over in BC Canada so regrettably not much use to you. Cheers C

 

[W1K1]

1904cc is a good size 90.5 x74 a web 163 , you can still use the stock heat exchangers and vintage speed. I ran one for several years in my type3, lots of bottom end torque and pulled to 5000rpm

 

[ozziedog]

Best thread I’ve read on here in ages fir advise on an engine rebuild and sizes , builds, applications etc. Funny how your mind and ideas change as you go through the build process and how many times have we seen peoples trying to build a bit bigger but keeping reasonably sensible then they go bananas when them new barrels arrive in the post. All of a sudden they’re ordering carbies the size of the Exon Valdize and an exhaust like the width of the channel tunnel.

Ozziedog,,,,,,,,,Brill yunt

 

[milfredo]

I’ve nearly hit the buy button (on reached out to view some) used second hand motors I’ve found. Most have 44mm exhaust and lumpy cams which I’m not interest in. Also would like a stock flywheel.

I’m spending money I don’t even have yet!

 

[K@rlos]

I’ve nearly hit the buy button (on reached out to view some) used second hand motors I’ve found. Most have 44mm exhaust and lumpy cams which I’m not interest in. Also would like a stock flywheel.

I’m spending money I don’t even have yet!

A stock weight flywheel is 100% what you want on a bus motor. I’ve even got 1 on the 2276 street/strip motor in my bus. Makes it for a nicer drive in traffic and all that inertia means great burnouts

 

[naskeet]

If you don't want to use exotic after-market, VW Type 1 air-cooled engine parts, consider a VW Type 4 style air-cooled engine. Those from the VW 411/412 were available with 1679 cm³ (66 mm stroke x 90 mm bore) & 1795 cm³ (66 mm stroke x 93 mm bore) displacements, with 80 hp & 85 hp respectively, at circa 5000 rpm.

These are reputed to be more robust than VW Type 1 style engines, have a higher-capacity, crankshaft-driven cooling system, which does not rely on the integrity of a fan-belt or dynamo/alternator shaft and has a proper full-flow oil filter as standard.

The displacement of the 1679 cm³ & 1795 cm³ engines can be readily increased to 1911 cm³ (66 mm stroke x 96 mm bore), if one wants or needs to replace the cylinder barrels & pistons.

 

[milfredo]

If you don't want to use exotic after-market, VW Type 1 air-cooled engine parts, consider a VW Type 4 style air-cooled engine. Those from the VW 411/412 were available with 1679 cm³ (66 mm stroke x 90 mm bore) & 1795 cm³ (66 mm stroke x 93 mm bore) displacements, with 80 hp & 85 hp respectively, at circa 5000 rpm.

These are reputed to be more robust than VW Type 1 style engines, have a higher-capacity, crankshaft-driven cooling system, which does not rely on the integrity of a fan-belt or dynamo/alternator shaft and has a proper full-flow oil filter as standard.

The displacement of the 1679 cm³ & 1795 cm³ engines can be readily increased to 1911 cm³ (66 mm stroke x 96 mm bore), if one wants or needs to replace the cylinder barrels & pistons.

Very good point! My only concern with a T4 engine is that replacement parts are expensive but then you have the reliability factor. I guess the gamble is with finding a low mileage and well maintained donor.

A friend of mine built a massive T4 engine that was bullet proof but cost him massive money but then his 58 split drove like a 911 and was almost silent round town.

 

[naskeet]

Very good point! My only concern with a T4 engine is that replacement parts are expensive but then you have the reliability factor. I guess the gamble is with finding a low mileage and well maintained donor.

A friend of mine built a massive T4 engine that was bullet proof but cost him massive money but then his 58 split drove like a 911 and was almost silent round town.

One of my father's patients had a salvaged 80 hp, fuel-injected, 1972 VW 412LE Variant engine (unlike the Saloon, this has same oil-filler & dipstick configuration as the 1972~79 VW 17/18/2000 Type 2 engine), who had originally intended to use it in a boat!?!

Sadly, there were no engine cover-plates or fan-housing, the fuel-injection wiring loom needed rebuilding and one or two of the Bosch D-Jetronic fuel-injection system components were missing, but at £50 in April 1991, it was a bargain we couldn't refuse and the internal components were in much better condition than the two complete 1974~75 VW 1800 Type 2 engines that we also acquired during the early-1990s.

It's doubtful that you would find a decent one that cheaply now, and even one that could be refurbished, would probably cost several hundred pounds. Whatever you choose to do, to gain a significant increase in torque & power, combined with long-term reliability, you are likely to spend a significant sum of money; especially if it involves buying new parts!

Had we not opted for a VW Type 4 style air-cooled engine, my second choice would probably have been a 1980~83 VW 1600 Transporter T3, CT-Series or CZ-Series engine, which also has the cooling fan driven directly by the crankshaft and a full-flow oil filter which screws onto the crankcase in common with the later 1•9 or 2•1 litre water-cooled flat-four engines.

Some people upgrade these CT-Series or CZ-Series engine, using the 76 mm stroke crankshaft from a 2•1 litre, water-cooled flat-four engine. It would probably be better to use the flywheel from the early 1•9 litre engine (215 mm clutch) rather than from the 2•1 litre or later 1•9 litre engines (228 mm clutch).

The picture was originally presented, as part of an introduction as follows, to the services of Laurie Pettitt, proprietor of The Bug Factory (aka Laurie Pettitt Engines), in Ayton, Berwickshire, who routinely undertook such conversions.

"Crank it up!", Products, VW Motoring, October 1998, Page 80.

One passing acquaintance of mine, by the name of John R. Long, in Burton Pidsea, near Hull, Humberside, England, had such a modified, 1776 or 1835 cm³, VW Type 1 style engine, built by Laurie Pettitt, for his 1971~79 VW 1600 Type 2, using the water-cooled VW Transporter T3 engine components, plus large-valve cylinder heads, mild cam, etc.

This picture, of a 1980~83 VW 1600 Transporter T3, CT-series, air-cooled engine, installed in a British specification, 1974 VW 1800 Type 2 campervan, was originally featured in:

David Eccles, "Peaches & Dream", Volkswagen Camper & Commercial, Issue 5, Winter 2001, Pages 6~9.

Note that the photograph has been incorrectly printed, with the left & right-hand sides transposed, which to those knowledgeable about 1973~79 VW Type 2s, would be obvious, from the apparent shape of the engine-bay perimeter and the postions of the spare-wheel well and computer-diagnostics socket!

A corrected, mirror-image version of this, may be seen on Photobucket, at the following link:

http://i275.photobucket.com/albums/jj287/naskeet/CT-engine.jpg

 

[gas1man]

I’ve nearly hit the buy button (on reached out to view some) used second hand motors I’ve found. Most have 44mm exhaust and lumpy cams which I’m not interest in. Also would like a stock flywheel.

I’m spending money I don’t even have yet!

Nothing new there then.........

J & P

 

[naskeet]

I’ve nearly hit the buy button (on reached out to view some) used second hand motors I’ve found. Most have 44mm exhaust and lumpy cams which I’m not interest in. Also would like a stock flywheel.

I’m spending money I don’t even have yet!

Even the VW-Porsche 914's VW Type 4 style, 1970 cm³, 100 hp air-cooled engine, has relatively modest 42 mm inlet & 36 mm exhaust valves.

Apart from that, the largest factory-standard valves used on the VW Type 4 style, air-cooled engine, was 41 mm inlet & 34 mm exhaust valves, for the 1795 cm³ variant with either 68 hp or 85 hp. The 1976~79 VW 2000 Type 2's & 1980~83 VW Transporter T3's 70 hp 1970 cm³, air-cooled engine, actually had 39•3 mm inlet & 33 mm exhaust valves; except for the North American variant with Bosch L-Jetronic fuel injection, which had relatively small 37•5 mm inlet valves.

As many engine tuners will acknowledge, it's not just valve size which is important when trying to improve volumetric efficiency, but inlet & exhaust port configuration, surface finish and minimization of flow resistance, consistent with keeping the atomized fuel in suspension; which typically involves re-profiling the valve-head cross-sections.

Bill Fisher, "How To Hot Rod Volkswagen Engines", HP Books, 1970, ISBN 0-912656-03-4

The annotated image below shows used, factory-stock, VW 1800 Type 4, 41 mm inlet & 34 mm exhaust valves.

Note the ridges, around the periphery of the valve seating angles (30º & 45º, for the inlet & exhaust valves respectively), where it adjoins the valve head & valve stem. Note also, the square-edged valve-head margins, which air must flow around, to enter or leave the combustion chamber.

These ridges and square-edged margins, have the effect of creating turbulence, which causes air-flow resistance and reduces the engine's volumetric efficiency.

The annotated image below shows used, factory-stock, VW 1800 Type 4, 41 mm inlet & 34 mm exhaust valves, whose valve seating angles (30º & 45º, for the inlet & exhaust valves respectively), have been back-cut (21º & 30º, for the inlet & exhaust valves respectively), to improve air flow.

Note the slight residual ridges, around the periphery of the valve back-cut angles (21º & 30º, for the inlet & exhaust valves respectively), where it adjoins the valve head & valve stem.

Note also, the square-edged valve-head margins, which air must flow around, to enter or leave the combustion chamber.

These residual ridges and square-edged margins, have the effect of creating turbulence, which causes air-flow resistance and reduces the engine's volumetric efficiency.

The annotated image below shows new, factory-stock, VW 1800 Type 4, 41 mm inlet & 34 mm exhaust valves, whose valve seating angles (30º & 45º, for the inlet & exhaust valves respectively), have been back-cut (21º & 30º, for the inlet & exhaust valves respectively) using a valve grinder. Using a lathe to rotate the valve about its stem axis, the residual ridge was ground smooth and radiused into the valve stem to improve air flow, using a hand-held grindstone and varying grades of emery cloth.

Note that the formerly square-edged, valve-head margins, have also been similarly radiused using a hand-held grindstone and varying grades of emery cloth, to reduce turbulence when air flows around them, to enter or leave the combustion chamber.