Discussion in 'Modified Shizzle' started by zedders, Oct 3, 2015.
When it's finished? I'll put the kettle on if I get there first.
It's not about squeezing the most out of the engine, it's making the most of modern grade fuels and allowing the chambers to fill properly
I've been forgetting to update this thread.
The engine is built.
The mega all whistles shiney bits spec is:
Standard case I got lucky with, I don't think it even needed a bore.
Standard 2L crank from same engine - again std size journals, not ground
Standard 2l cam (or was it the 1700 one @Robert Parry ?) if indeed they are different which IIRC they weren't noticeably. Again used.
Standard refaced solid followers.
Standard ali solid lifter pushrods.
Standard 1700 rockers - they aren't so chunky and heavy as the 2l ones.
Standard T4 oil pump, again probably from this engine.
Standard oil pressure spring.
Standard oil cooler
So it's all made from the VW engine's I like most so far - T4 2L and 1700. I like 1700 because it's a whizzy engine with quite big valves for it's size (as they go) and I like 2L for it's torque. Something inbetween but with more guts was the aim.
1700 heads. When you are used to looking at the convoluted inlet port on a T1 head, the T4 one is literally half a smartie tube. Even I could see the advantage of that. Looking good. I struggled and failed to get a useable pair of 41mm 1800 heads. 39.3mm 1700 heads were settled on. They have their advantages too. The valve seats were heavily worked to get the most from 42mm stainless valves and, er lots of other stuff. Rob might contribute if he sees this. They were also machined to fit the 104mm barrels and the combustion chambers reshaped to cope with the huge piston diameter and lower the compression.
104mm barrels and pistons made by AA. These appear to be quality items, rob had to grind slightly to accomodate the studs here and there and reports they are very hard steel. As they should be. the top ring is chrome - hard wearing but takes longer to run in.
H-Beam rods as "demanded" quite rightly by @Paul Weeding. These are 1/2 the weight of the standard ones. My one avoidable expense I'd say, but no regrets.
I've behaved for 500 miles. First 350 miles I had less than 1/2 throttle by design but it still went 70 no problem. Not that I did. Just the once then.
I only have my last engine to compare it to which was in a very noticeably lighter 68 tintop and I'd say both buses go about the same, but this one does it 2,000rpm slower and the bus is heavier. Therefore as far as HP goes I'm going to guess around 150. I wish I had the torque graph for the last one because this will pee on it. I've been overtaking today.
I have original heat exchangers and a standard second hand Ernst silencer I had to weld a tailpipe onto. Think Tailpipe is T25.
Carbs are DRLA40's with 32 vents. That's the biggest I have, I will probably get some 34's to try just because...
6 rib box
228mm flywheel and standard clutch.
It's quiet, I can hardly hear it! When I put my foot down it growls, but you'd hardly notice, nobody will stare at the old fool.
I can see an advantage of building a big T4 engine, the parts might be more expensive, but if you try and build a big T1 the first thing you discover is that everything pre-used is knackered and/or too small. Everything on the T1 was new apart from the distributor drive and the crank and that was from a wasserboxer because the T1 cranks are too small.
Getting 42mm inlet valves into a 1.7 head just takes time, I have done the same using 1.8 valves although they are smaller. I open the inlet ports approx 4mm at the manifold end and shorten the guides by 10mm and taper them slightly. The inlet port is opened to fit the 42mm valves and the seats have a 3 angle cut. This forms a taper all the way beyond the bottom of the valve seat, the result is a venturi below the valve, faster air speed. The port is them flowed and finished with a slight polish. The exhaust was done the same way except for the guide. I do not remove all of the valve guide boss in the port, However I do reduce it and shape it so as to encourage flow around the valve and boss, the guide was shortened again by 10mm and a taper left on the guide. The guides where not fully pressed home into the head but fitted as per type 1 heads, this gives more support. The engine performs just how I expected it to.
And just how I wanted it to.
I've been to Lincoln and back today for a cuppa with my dad and say hi to @Purplepantyman. 870 miles since Christmas day.
How would that lend itself to an otherwise standard 2 litre running with dell carbs and standard exhaust set up do you think.
@zed forgot to say. I have some 34 vents if you want to play. They are brand new! Im not gonna use em any time soon or possibly at all!
Have been following your engine build Zed with great interest, love the ethos of a great increase in torque coupled with enough usable revs to make motorway cruising easy. I guess this motor must push the bus out of roundabouts & uphill at a rate that brings a big smile to your face Have you any idea on what it's like on fuel yet ?
It works really well on all the type 4 engines. I have done this many times using the 1.8 inlet valves. On a 2ltr I would not use 42mm valves as you would lose power at lower revs with a std cam fitted.
Not yet but I did brim the tank and take a mileage reading yesterday. Must do something with the gauge which read just above the red but only had 3l of fuel left in the tank, or at least I got 52l in when I filled up. That's as near to running out as I've been since i was 19 and learned a hard lesson.
OK I am curious to hear what the consumption is like, my guess is it won't be much different to the normal 23 - 27 mpg as with all the torque you won't have to drive the wheels off it to make decent progress. Last time I ran out of fuel I was 21 & it was in a Capri funny how you learn quick ! Just thinking the Capri was on an X plate & about 3 yrs old at the time - how old do I feel now
I wrote the mileage on the receipt and promply threw it away.
I know the route I took and miles and guesswork for some extra miles TBH but it came out as 20mpg - that's very rough! After my blocked oil cooler pipe fiasco, an even cruder (I couldn't bear it) calc put it at 16 - that oil pump must have been fighting so hard it sapped 4mpg.
My 20mpg did involve 10-20 miles at 70mph and some sprightly over-taking from time to time. It shouldn't be any different until I ask it to do more than a standard engine. I read somewher that it takes 30HP to drive a bus at 50mph and assuming similar effeciency it must take the same fuel whatever the engine size? If it's more efficient which I suspect it jolly well is, and I drove it gently I think I'd be pleasantly surprised.
Broadly speaking, the specific efficiency (fuel used per kW produced) of a petrol engine is greater at full throttle than at part throttle (throttling losses). With a bigger engine, your cruising power is generated at a lesser throttle position so the relative efficiency of the engine is lower, needing more petrol to produce the same power. That's why smaller engines are more economical in day-to-day use than larger engines.
You had it on the Dyno yet sounds intresting
For the sake of completeness, I did go to a bit of a rubbish rolling road and came home with this.
Great torque curve!
I have a 2.9L itch that might need scratching at some point, the only thing stopping me is that this one is going to be hard to beat for a camper.
Your CR is quite low, isn't it? Might take a bit of turbo boost?
All vw a/c engines standard, run 7.4, 7.5 CR. Mine is under 8. It runs cool. Say no more.
2.9i turbo? Hmm, probably not. Far too much fiddling and worry. Camping remember?
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