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Post by Zed on Sept 22, 2019 14:50:23 GMT
My max HP is at 70mph.
Below that speed my torque/HP crossover is at approx 60mph.
Below that I have bags of torque to increase the lower rev HP.
It's great for all speeds normal driving at the expense of 3rd gear razzing - I'm happy with that.
I will admit I wonder what a little bit more cam would be like... but not enough to try it - if I didn't like it as much I'd have to do it all over again or live with it knowing it was better before, plus it would be difficult to undo after also altering the CR for a cam like a C25. It took enormous willpower and months of hand wringing to resist changing the cam when the engine was built but I kept on telling myself that I like the nature of a stock 2L but wanted a bit more of the same which is pretty well what I got.
Presently I'm experimenting with timing again and finding it likes more advance and more advance lets it rev higher. When I'm done I'll find a RR and go again just to see, I have a suspicion that lack of timing caused some of the torque drop off at 4,000 rpm. Not that I want it to rev higher, I like the peace and quiet.
And lastly - 5 years ago if anyone was planning to build an engine with a stock cam my opinion would have been that they were completely insane to leave that power possibility "on the shelf". The reason being that a 2L isn't big enough for a van IMO and power anywhere you could get it was a good thing. Now I think it's easier to increase the capacity instead and get that gain throughout the rev range. So, maybe if I were limiting myself to 2L I'd put a mild cam in it...maybe. But definitely not with large valves and a fat header too.
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Post by deefer66 on Sept 24, 2019 6:08:53 GMT
After a quick re-confirm with Coolair, their web cam 'stock' is the stock hydraulic, 223° duration, the 140 grind "stock" I.e 914 is 247° but they don't sell this one.., the web cam 73 takes it up to 262° but it's out of stock. C25 is 270° for reference.
What I'm unsure of is without the increase in displacement I'd not be making up the difference in torque at lower revs.... perhaps sourcing a 914 cam is a reasonable compromise of increasing breathing without pushing curve too far on a "smaller" engine....
.....Or just going to aircooled.net and get a 73/86 ordered ! Cost wouldn't be that much be spread out over the life of the engine...🙄😁
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Post by Zed on Sept 24, 2019 8:15:53 GMT
I thought the 73/86 one might be a good compromise when I was last looking.
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Post by 77westy on Sept 25, 2019 12:31:13 GMT
What capacity are you aiming for? I had a C25, 1800 heads, dished pistons and low CR on my 1971cc (standard 2.0l) engine for 8 years, plenty of torque at low revs for town traffic and climbing cols – even with 500 kg of wood pellets in the Westy. Web cams are far better than Scat and just about all the other manufactures and a 73/86 would be an excellent choice but get the SCR at the top end and the deck tight.
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Post by deefer66 on Sept 25, 2019 13:52:28 GMT
So in answer to the question.. I choose 73/86..
Still weighing up engine size options now...temped to go 2056.
Just need to find a way to get SCR high enough to let DCR cope at 8% less... with those big old 1800 chamber volumes. At least a tight deck shouldn't be a problem..
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Post by 77westy on Sept 25, 2019 14:49:18 GMT
If you go for 96mm B&P I can recommend AA double cast Biral cylinders to keep the temperature down, the quality is spot on these days and the price is not much more than iron cylinders. Ideally get shallow dished pistons or use flat tops and open up the combustion chambers slightly – it doesn’t need much and you can unshroud the valves by taking the chamber out to the edge of the cylinder. This kit looks good aapistons.com/products/vw-porsche-type-4-96mm-piston-and-biral-cylinder-set
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Post by deefer66 on Sept 25, 2019 15:02:04 GMT
That's the set I was looking at.. Doesn't need chamber opening, with a deck height at 1.2, the 58cc chamber in the 1800 heads would give a static at 7.97, dcr at 7.36 at an optimistic 40 ABDC close!
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Post by 77westy on Sept 25, 2019 17:27:45 GMT
7.36:1 DCR is far too low - I suppose I should say in my opinion (and experience). The DCR needs to be 8.0:1 or slightly higher but not lower, you’re almost a point too low for the engine to be efficient and take advantage of a decent cam. Are you using numbers from bus dished pistons? Flat tops should make the SCR too high.
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Post by deefer66 on Sept 25, 2019 17:35:23 GMT
That's with the 7cc cut out for the AA pistons.. recon a quick 1mm skim of the heads to tidy them up while getting k-lined should knock 5cc off the combustion chamber and get me 8 dynamic and 8.5 static...👍
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Post by Zed on Sept 25, 2019 17:48:16 GMT
Contact AA and ask what the effective (case to head) length of the cylinders is and compare to yours. As they are advertised for 71-78 stroke they either expect you to use 3.5mm shims for the 78 or turn down long cylinders for 71. Just pointing this out because my AA 104 cylinders were advertised similarly and were extra long.
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Post by 77westy on Sept 25, 2019 18:17:42 GMT
Pistons with a shorter compression height are used for 78mm (and longer) strokes; I only had to use just over 2mm shims for the 80mm stroke and the AA cylinders were the same length as the VW ones I took off – 91.79mm.
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Post by Zed on Sept 25, 2019 18:36:56 GMT
Pistons with a shorter compression height are used for 78mm (and longer) strokes; I only had to use just over 2mm shims for the 80mm stroke and the AA cylinders were the same length as the VW ones I took off – 91.79mm. I'm sure you're right. The kit you linked to says 71-78mm, so did my 104's. There is no choice of pistons in these kits. I'm just trying to avoid deefer suddenly finding out his cylinders are 3.5mm too long, it's worth an email? Them there yanks will be up so probably get a quick answer.
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Post by 77westy on Sept 25, 2019 20:44:41 GMT
Pistons with a shorter compression height are used for 78mm (and longer) strokes; I only had to use just over 2mm shims for the 80mm stroke and the AA cylinders were the same length as the VW ones I took off – 91.79mm. I'm sure you're right. The kit you linked to says 71-78mm, so did my 104's. There is no choice of pistons in these kits. I'm just trying to avoid deefer suddenly finding out his cylinders are 3.5mm too long, it's worth an email? Them there yanks will be up so probably get a quick answer. Definitely worth an email but he’d need to know the compression height of the pistons as well as the cylinder length.
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Post by Zed on Sept 25, 2019 21:53:03 GMT
I'm sure you're right. The kit you linked to says 71-78mm, so did my 104's. There is no choice of pistons in these kits. I'm just trying to avoid deefer suddenly finding out his cylinders are 3.5mm too long, it's worth an email? Them there yanks will be up so probably get a quick answer. Definitely worth an email but he’d need to know the compression height of the pistons as well as the cylinder length. It's all on the link you put up. But there is/was no mention of the barrels being extra long when I bought mine, it was a bit of a surprise to say the least though it all sort of worked out in the end. As you know, I didn't plan my engine in any detail deeper than as many original VW parts as possible/ big pistons/stock cam/behaves like a mild turbo diesel.
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Post by 77westy on Sept 26, 2019 6:53:17 GMT
Definitely worth an email but he’d need to know the compression height of the pistons as well as the cylinder length. It's all on the link you put up. But there is/was no mention of the barrels being extra long when I bought mine, it was a bit of a surprise to say the least though it all sort of worked out in the end. Ha-ha, so it is, it wasn’t the kit I used and I didn’t notice the detail. A few years ago, AA barrels were often longer than standard by around 3mm but mine bought 3 years ago were normal length. The supplier (DRD, now sold to EMPI) anticipated cylinder shims between 0.075” and 0.100” being required and I ended up with 0.090” to get the deck height and CR I wanted.
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