The Hyabusa V8... directional conflict?

[Kozy]

Having a look at the CAD model of the Hartley Enterprises Hyabusa dervied V8, I struck me that one of the engines must essentially be spinning the wrong way in order for it to work. What is involved in getting the engine to turn backwards like this?

[LeonOfTheDead]

uhm...nothing?!

I mean, a lot of engines are used in different positions in different cars, so the problem is more likely this: hot to be sure it is lubricated correctly, so something that involve the oil pump more than the engine it self, I would say at first glance.

[Bob]

uhm...nothing?!

I mean, a lot of engines are used in different positions in different cars, so the problem is more likely this: hot to be sure it is lubricated correctly, so something that involve the oil pump more than the engine it self, I would say at first glance.

I think you misunderstood the question, but your answer was still correct. Excuse me if I'm wrong but I think Kozy was asking about the "two" straight fours rotating the crankshaft in different directions. It really isn't problem since piston motion is determined by the crankshaft and obviously the crankshaft for the V8 is very very different from the 4's which comprise it. Leon is right- the issues with such an engine is that each bank of cylinders was designed for an individual oiling and cooling system, etc.

[Matra et Alpine]

Can confirm, all the V8s based around the 'busa block have their own single crank.
If you look closely at any of them you see that the blocks are slightly offset to ease the crank design.
Matra created a "V8" by physically tying two I4 engines together. It had a horrendous gear/chain "contraption" to combine the power Look for Matra U2 for info on your favourite site ! Was intedned to be a low cost sports car with the performance of a Ferrari. Unfortunately they realised they woudl have to uprate the brakes, suspension, 'box and the added cost took them into Ferrari prices .... adn then the first oil crisis hit

[moparbee]

Actually, reversing the direction the engine turns is pretty sinple, really. The biggest issue, and the one that defines the direction and timing of the rotating parts is the camshaft(s). Have camshafts machined to the same specification as the "normal" direction motor, but all the lobes going the oposite direction. Not really that hard, people have for years gotten custom camshafts made to change the firing order on motors, and even to reverse the direction for specific applications (like installing different engines in a VW Beetle, or a Corvair or other such thing).
Oiling, cooling, and timing chain running is really just part of engineering the new "siamese" block in the first place, and make a crankshaft that will space all the cylinder firings out evenly.
All this is easier said that done, obviously, but still...not exactly brain surgery.

[henk4]

Can confirm, all the V8s based around the 'busa block have their own single crank.
If you look closely at any of them you see that the blocks are slightly offset to ease the crank design.
Matra created a "V8" by physically tying two I4 engines together. It had a horrendous gear/chain "contraption" to combine the power Look for Matra U2 for info on your favourite site ! Was intedned to be a low cost sports car with the performance of a Ferrari. Unfortunately they realised they woudl have to uprate the brakes, suspension, 'box and the added cost took them into Ferrari prices .... adn then the first oil crisis hit

If you take a good look at the glorious Cosworth DFV engines, you will not the the blocks are slightly off-set too. Anybody who ever built a Tamiya F1 kit will have noticed

[Matra et Alpine]

Actually, reversing the direction the engine turns is pretty sinple, really. The biggest issue, and the one that defines the direction and timing of the rotating parts is the camshaft(s)

Also balancers and potentially larger than the cam issue as it's not jsut a profile, the whole dynamics of longtituduinal resonance alter.

[Matra et Alpine]

If you take a good look at the glorious Cosworth DFV engines, you will not the the blocks are slightly off-set too. Anybody who ever built a Tamiya F1 kit will have noticed

All V8s who share a block casting have to offset.
Yes, built the Lotus 72 and the Tyrrell .... did make F1 kits a bit boring back then as the engine was the same for most
STILL not built my flat-12 Ferrari kit !!!

[henk4]

All V8s who share a block casting have to offset.
Yes, built the Lotus 72 and the Tyrrell .... did make F1 kits a bit boring back then as the engine was the same for most
STILL not built my flat-12 Ferrari kit !!!

try the Matra for a change

[IamPopeye]

Hi all,

First post for a noob, why not jump in with both feet!

Like others have pointed out, single crankshaft so the only things really spinning the wrong way are the camshafts. No problem there, again as pointed out, just get a pair of essentially mirror image bump sticks made.

The thing that I've always found curious is the camshaft drive. But it's never made me sufficiently curious, since I'm not planning on building one - yet! I'm thinking out loud here, so please don't shout at me too loud if I'm lost in the woods and missing something obvious to others!

Are the cams driven by a center chain between 2 and 3 on the 'Busa? Offsetting the bores for the width of the big end of the rod is obvious. Unfortunately, that would also offset the cam drive chain for the one bank of cylinders. Maybe I'm missing something here, but if you added an extra camshaft drive sprocket to the crankshaft for the offset bank, this would throw off the required spacing between the crank pins for the middle pairs of cylinders...am I missing something here...need to go find that 'Busa illustrated part book and manual!

I guess you could set up the two banks of cylinders with one as master and one as slave, at least as far as camshaft drive. The master camshaft chain would drive off the single crankshaft sprocket. The slave bank's camshafts could then be driven by a secondary which was driven by the master bank's chain. Did that description make sense? Only issue I see here is reliability and strength since I'd make the assumption that the OEM 'Busa cam drive was sized to support one set of cams/springs/valves. Doubling the load by having the secondary drive pulled off the master chain would likely lead to premature failure.

Does anyone know how Radical, Powertec or Hartley handle the camshaft drive?

Regards,
Tom

[Matra et Alpine]

The heads are based on stock Hayabusa units and so the cam drives are at differing ends. So the crank has a chain drive sprocket on both ends of the crank.

These ... Boardroom Power Struggle .. can help see it.
Sure I had a pic of the crank somewhere, but can't find it

[IamPopeye]

Thanks Matra!

I just found a pic of the Hartley with the valve cover off and figure the same thing! Was going to post my own answer but you beat me to it!

Cheers!
Tom

[Matra et Alpine]

snap Iam ..... I had been looking for Powertec RPA stuff and only now realised it was Hartley's version.
This video makes it very clearl and will ikely answer all the questions anyone else might have
V8 SIMULATION PAGE...
http://www.hartleyenterprises.cityma...mpressed2a.mpg

[roosterjuicer]

how much horsepower does that motor make? does it rev as high the 4's in the motor cycles do?

i've always wondered why honda never tried slapping two s-2000 4 cylinders together and making a 480hp v8 that screams at around 9000 rpms, i think that would be sweet...super sweet.

[Matra et Alpine]

All the specs for the options are on the Hartley page and you can find the Powertec RPA either at Radical or Wiki.
The Honda block is larger and heavier than the basis for these guys.