Thanks Its not for art though there is a lot to be gained from working vw aircooled heads especially the autolinea castings I started off doing ford cvh heads for grasstrack and streetracers
Forget headwork for a while and remember the yank saying theres no replacment for cubic displacment Capacity = torque and thats what you need in a bus and torque from standstill to 5000 rpm is perfect for a heavy camper
Raising the gearing merely makes for a more comfortable drive IMO. A measureable amount of power is required to push a bus along at say 60mph. That power produces the same heat. Lowering the rpm and maintaining the speed doesn't make a difference to the heat produced. The 1600 fan/cooling fins we are stuck with and hence there is a point when the cooling system cannot keep up. T4's were designed with the pots further aparts and more room for cooling fins + they have a better cooling air fan and delivery system so you can go a "bit" faster. If you want increase your cruising speed I think a Subaru is the only real way forward. On the plus side you can make an air-cooled engine that will accelerate like stink and go 100mph- just not for more than 2 minutes.
I agree with Alex, if you are going to have the case machined you may as well increase the stroke as well as the bore. Various people have mentioned cooling on bigger cc engines, I have a different opinion. I think well thought out engine spec and build is the most crucial when it comes to cooling. If something isn't right then extra cooling won't fix it. 1. I ran a 1776cc engine for ages with no extra cooling and the only engine 'breathing' was an open tube pointing up from the oil filler. It ran great and i never found it running hot. After having some extra head work i did have an external oil filter added. Full spec below. @paradox i think this spec may be useful for you. 2. Then i had a different 1776 better spec on paper, with extra external cooling and a fancy pants oil breather system. It ran hot! Full spec below 3. Then i had a 2110cc with cooling and oil breathing, which runs fine temp wise, I think i could get away without the external cooling on it. Full spec below For the 2110cc I changed the gear box from a 1600 to equivalent ratios of a 6 rib. In an old post i noted the before and after temperatures, revs and speeds (below). Apologies for the length of this post, but some of this may be useful, it wasn't originally written for this post Engine Number 1: 1776cc Standard Forged VW crankshaft and stock conrods. Mild performance cam: Bugpack 4061 with 370 duration and 396" lift Oversized New Barrels (I think they were Mahle) & pistons. Pair stock valve VW twin port cylinder heads, cut for 90.5mm (1776cc) with mild port, Stainless steel valves, heavy duty springs & aluminium rocker covers Kadron carbs, with linkage, air cleaners etc. modified for use with vacuum distributor for improved acceleration and economy. So this engine was fairly standard except the heads and the cam. The van would 'fly' up hills and would cruise at 70mph with no problems at all. I knew very little about vans and engines, but everyone told me the engine was ace and I don't think I was ever overtaken by another bus. I drove wherever I wanted without even thinking about it. I loved my bus and enjoyed driving it. I changed it as I thought it was knackered, but I think it was just a faulty oil pressure switch! Engine Number 2. Off the Shelf 1776 Crankcase: Brand new extra strong Aluminium crankcase, drilled and tapped for full flow oil system using the top and bottom gallery method. Crankshaft: Original German forging re manufactured to OE spec. Drilled for 8 dowel holes and then dynamically balanced Flywheel: Brand new cast lightened flywheel with 8 dowel holes Connecting rods: Orig german forgings, remanufactured to OE Spec Oil pump: Melling cast iron Camshaft: Engle 110. Valve duration 284 degrees lift with stock rockers 0.430" Camfollowers: remanufactured to OE spec Barrels & pistons: new barrels fitted with forged 90.5mm pistons, manufactured by MAHLE. Pistons balanced to 1 gram of each other prior to assembly Pushrods: New heavy duty steel manufactured by EMPI Rockers: Stock 1.1:1. Re-manufactured Rockershafts: new bolt up units supplied by EMPI Tappet screws: Heavy duty elephant foot style swivel feet by EMPI Cylinder Heads: EMPI 044s which are stronger than stock style heads as they have extra material around the combustion chambers. They also have larger air intake & exhaust ports. Each is fitted with stainless 40mm x 35.5mm valves, heavy duty springs, steel retainers & long reach spark plugs. External oil cooler, fancy pants oil breathing So the spec of this engine was great on paper, but it never felt as good as the previous 1776 engine, it got hot, p i s s e d oil and was under powered! I tried this engine with the Kadrons and then changed to Dellortos, after being told my Kadrons were not powerful enough to fuel the engine. S h i t & massive waste of money. Steer clear of ‘off the shelf’ engines. This engine caused me 5 years+ of grief and i didn't feel confident driving anywhere in it. Engine number 3– 2110cc stroker. My current engine, which I love: Spec: Cylinder heads Mofoco 40x35.5 valves, 90.5 barrels & pistons, Web Cam Type 1 Camshaft, Grind 111, 1.1 Rockers, 00-602 is designed for 1.1 rockers, and it's specs are .476/476" Valve Lift with 1.1 Rockers, 272/272 degrees of advertised duration, and 238/238 degrees of duration at .050" checking clearance. Counterweight crank. Loads of machining on the case to fit the longer stroke crank. All relevant bits balanced & set up correctly. Total seal piston rings. Full spec available. Engine temp and gearing information from 2110cc engine: New Gearbox now fitted, so I thought i'd update this thread with the impact it has made. New box was built by Bears and is based on an 002 box with same gears as standard, except 4.57 ring & pinion (apparently it's only the final drive that alters the overall gearing). Tyres are 185/65 R15 New gearbox: 70mph @ 3,200 rpm. Doing 105 Miles on motorway & a roads at 70mph produces oil temp of 80c Old gearbox: 70mph @ 4,000rpm. Doing the same 105 mile journey as above produced oil temp of 90-95c Summary: Very pleased with gearbox so far. I would thoroughly recommend Bears. I'm glad I went this route rather than fitting a 2nd hand 009 gearbox or buying a freeway flyer from VW heritage. New box feels nice and tight. A gearbox with 4.57 final drive is better suited for a 2110cc engine than a 1600 box. Engine temperature has gone down as engine not working so hard for same driving speed - some thought it would run hotter as fan wouldn't turn as fast. Fuel economy has improved by approx 2.5l of fuel per 100miles. I've not done much driving around 'town' yet. I hope this info will be helpful for people with large engines who are considering a new gearbox. I obviously don't drive the van for fuel efficiency but I'm happy it is slightly more efficient now. If any of you need to justify the cost of a new gearbox to yourselves or your other halves then i roughly calculate that it will pay for itself in about 28,000 miles!
You have a more sensible cam than me Paul. I'm starting to regret mine which is similar to the one you had in engine number 2 - too much duration for a torquey engine. I'd win a race though I reckon. And I'd love to know what your CR is. Maybe I went a bit mad and that's my extra heat.
I don't even understand duration! I'm sure you would win a race. You can test my compression at the next techenders if you like, or i could try asking the engine builder
It's the compression ratio your builder designed it to have I'd like to know. Where is your oil temp measured? Mine is as it's pumped OUT of the engine. Perhaps I should be measuring the temp going back in and on to the bearings via the standard cooler. Maybe mine isn't hot at all?
Indeed the cost does raise a fair bit when you move to a stroker crank Different pistons The crank its self Cut to length push rods getting the flywheel drilled for 8 dowels etc etc If i can raise the extra cash needed at the time i come to build my engine i would like to increase the stroke as much as the pistons i have will allow Ill still be keeping the stock carb and inlet though
Valve overlap - the more overlap, the higher the revs needed for the gains, something to do with the flow of exhaust gasses helping to pull the next charge of mixture in. The problem is at lower revs that flow isn't happening and so you are left with some exhaust gasses in the mixture instead.
I'll ask him. My temp is measured with dipstick sender it reads 5c lower than true temp - I put the sender and a normal thermometer in boiling water to test.
Yeah i read that dude Ive got my spec more or less nailed down cost dependant It will give up the ghost just about 5000 rpm but will have enough torque to drag a trailer full of logs down a dirt track Living up here i wont be making the journey to many shows using the motorway But i have all of the dales the north york moors and the lakes to go camp in and explore Also the paravan will be used to earn its keep So a grunty low end power practical and simplistic build is the way forward
My 1600cc engine had cam lifter failure shortly after i bought the van last year & needed sorting. I set about rebuilding the engine myself and was keen to add some upgrades, but I didn't want to go mad with the £££. I eventually ruled out machining to increase cc - turns out it is quite a specialist job (not something my local experienced machinist would touch which i was surprised about) and the costs (and time) do seem a bit hefty IMHO.... In the end I just went for 1641cc p&b which are a straight swap and a scat c25 cam & new lifters with new (better?) valve springs. I also replaced my oil coiler - mine looked dodgy. All this cost me about £400 ish with gaskets and bits and i was done in approx two weeks with basic tools and haynes manual. I spent alot of time cleaning the case. My bearings all looked ok and were carefully cleaned but it would have been sensible to do these too... But i didn't have a pully to hand & i didn't want to open up prospect of stuff needing to be reground etc.... Probably should have replaced my exhaust valves too whilst in there. But anyway, once back together it definitely ran alot 'better'... I then added a £40ish accuspark dizzy with vacum advance which really was transformational. 6 months on and all dialed in now and i'm very pleased wth how it goes. It seems v happy to cruise at up to 70, goes up most hills i encounter in 3rd and every now and then pulls a one ton trailer full of logs home! We'll see how it goes with family campin trips this summer.... But in terms of bang for buck, i'm pleased with what i got for my £600ish
For me, if i want to splash more cash for more performance i'd next go: 1. Twin carbs and exhaust 2. Having heads worked on 3. Then think about increased cc....
@zed I asked my engine builder about my compression ratio, mentioned yours was 9:1 and heat etc. I've posted his reply as it may be useful for others as well ---------- Forwarded message ---------- From: Harry Harpics<harryharpics@btconnect.com> Date: 3 June 2015 at 14:58 Subject: Re: Compression Ratio - NOT URGENT To: Paul Hi, that high compression will be his problem. Tell him to Google Gene Bergs findings on compression versus fuel octane rating, it was done many years back, but he was and his findings still make him the “main man” for all things air-cooled VW. I rarely go over 7.9 – 1 as this allows the use of normal 95 octane unleaded. For 9.1 he will need over 100 octane fuel. Regards Paul
