There is an almost direct relationship between torque and capacity and engines of the same capacity but different bore/stroke ratios will produce very similar torque. If we say an engine develops about 70ft/lb per litre, a 2110cc will make about 150ft/lb and a 1910cc about 135ft/lbs. These numbers are a comparison rather than absolute values, but they’re not far off. Bottom line is you’ll feel the 200cc difference, and a big difference from a standard 1584cc. The bigger you make the engine the more heat there will be, or rather potentially more heat because you can keep up with traffic on motorways and accelerate up hills. Be wary when someone says they’ll adjust the compression ratio so that the engine runs cooler. A cam has an optimum CR range where it will work efficiently, so if they simply lower the CR the engine loses efficiency. If the CR is lowered the cam should also be changed. A cam moves the torque up or down the performance curve. Low lift short duration cams make maximum torque at low revs, high lift long duration cams develop maximum torque at high revs. And because bhp is torque x revs it makes more bhp with the same torque, but it makes less torque at low revs. If only we could have good low rev torque and good high rev bhp - somebody should think of variable valve timing… For what it’s worth I choose a cam with the power band where I wanted it and used the highest static CR without the engine pinking. But it’s a 2316cc Type 4, Scat C25 cam, 9.0:1 CR.
The ‘ no replacement for displacement’ is a good argument but I’m not completely sold into it .. FI and Turbo the Marmite out of it ..
You can FI the hell out of it but make it bigger and it’ll make more torque, a turbo just makes the engine think it’s bigger, like supercharging or NOS injection.
In practical terms in a bus, and engine that makes it's peak torque lower down the revs like all stock engines, do not make much peak power for their potential, but because power is torque x revs, having high torque at lower revs means more power at lower revs and a more pleasant driving experience. I'll put up my extreme example to make a point - it's 2.4L stock cam Type-4. It makes just 100HP peak. It could quite easily have had a big cam in it, saved a CR headache, had a more efficient engine and 150HP, but I wouldn't have more than a 1600's peak power at 17-1800rpm - I'd have had to go down a gear to get the revs up to where the engine worked better. Having had a 2l size type 1 with a C35 cam (peak 135HP - similar cam to the one you are proposing) and now this engine, while the other was better for racing around the roundabouts in Milton Keynes, this one wins hands down for an easy drive. Yours wouldn't even be any good at high revs because it would self destruct if it managed it due to the crank and case. Mine had a superior crank, flywheel and clutch from a wasserboxer and an aluminium case, big valve heads twin Dellorto DRLA40 carbs, a fat exhaust system and revved smoothly off the 6,500rpm scale - yours would be limited to 4,500rpm (on occasion) so you wouldn't get the good out of the cam but you'd be giving up lower rev power.
If I were going again I'd give serious consideration to a stock 1700 type-4 with a turbo. My favourite engine with the power it deserves, what's not to like?
What puts me off (as well as tuning for a turbo) is the the exhaust for type-4 turbo, there's not a lot of space. I suspect this steered LHU1281.
that and it’s something out of the norm .. my 1700 with twin Dell 36’s in the bus is a sweet combo .. 1700 gives the best sealing ... A lot is to do with component choice and quality / blueprinting etc . What makes a Raby camper special @ nearly $20k ? Fuel injection fuel injection fuel injection fuel injection
Not for me. Thanks to the internet he can be found far too many times saying one thing one day and the opposite 5 years later, always with unquestionable authority. Now he might be good at it, might be full of bull or a bit of both. His engines are not impervious to going wrong, but he'd only let you have an engine if you butt kissed him, held out your wallet and said " please, take it all" so I doubt one ever hears about it.
I thought a Raby Special was more like $25K. He charged a high price for the work done, and the parts supplied, plus an extreme premium because he has a good reputation. I believe reading his postings over on the Samba he has stopped making them because he cannot source quality T4 engine blocks any more. So he does Subaru work now. It is strange though that in the USA , they consider a turbocharger a cheap option to more power... And turbocharging a solid engine like the 1700T4 or the 1776T1 (sort of similar ) is more likely to last than building an extremely large engine and then adding a turbo.
Nobody has actually stated the obvious... Forget all this machining malarkey, just buy a 6 rib box and a boggo 2 litre t4 engine - job done There's at least two people I know who've gone Subaru and are selling their good 2 litre engines. Sent from my SM-G960F using Tapatalk
Raby stopped working on Type 4 engines when he ran out of customers prepared to pay for an engine what most of us would pay for a good Westy - with a Type 4 engine. And there is nothing special about a Camper Special engine.
He's been building a few of late, just posted on Facebook, he's built a 2563 for a Porsche 914, I dont much about the components, he hasn't said much else.
I noticed that he’d recently made a VW/Porsche engine or two; has he exhausted the supply of rich Scooby owners? He’s also working on new cylinders as an alternative to the Nickies that are/were the best. His engines are built with meticulous care with the best components (the US can supply).
He doesn't post scooby conversions from what Ive seen, Skills has taken over with quality conversions in the US.
Reading thesamba you get mixed messages, it talks of him developing them and that's about it. Maybe it is supply only? It'll be top dollar either way!
Where are you based, when you decide which way to go you could do worse than visit me mate John Gurney here in Shrewsbury, run your specs by him. he is a good engine builder with a lot of experience with fast VW [or stock] engines and you wont have to spend the earth. While your here John Walklett can sort your box. Google them both if you need any references, As far as I am concerned both great blokes who tell it how it is and wont rip you off.
When you mean ..not a lot of space in the exhaust ,as in a backing up and not getting the hungry engines exhaust gasses out quick enough, and disabling power out put ?