Combining two inline 4s to build a V8 ?

[woohoo]

HI

This is going around my head for a bit, and I cant really find an answer for it.

Is it possible to combine two 4 cylinder inline engines to create V8 ?
Like taking a real inline, make a new crankcase and crankshart, edit the timing and voila, a V8 on the cheap.

I know the Porsche 944 engine is half the 928 V8, but is it possible the other way around ?
Like gluing two Alfa twin sparks together ? (they sound good)

Or a boxer 8 to simplify timing... ?

[mpower]

theres one succesfull company that use suzuki hayabusa motorcycle 4cil heads to make v8

[747heavy]

Yes, depending on how you do it, it´s called a U-engine or Block 8 (google it), the you have two crankshafts which are then joint onto a common drive.



There are such engines around which are based on Hayabusa bike engines, to make a very ligth and compact V8 for self made sports cars.
http://www.holeshot-racing.co.uk/index. ... hartley-v8

If you make your own crankshaft you can build a "real" V8 out of two I4 engines.

[mpower]

they started using yamaha fzr1000 heads...first carbs later inj.

now busa

done some records in radical's

http://www.powertecracing.com/pdf_downl ... engine.pdf
http://thekneeslider.com/archives/2007/ ... er-455bhp/

[Tim.Wright]

Like taking a real inline, make a new crankcase and crankshart, edit the timing and voila, a V8 on the cheap.

How on earth is making a new crankcase and crankshaft considered on-the-cheap?? The crankshaft is probably one of the most expensive parts on the engine.

Not to mention, if you go down this road the only thingd you can use from the whole 4 cyl engine is the head, pistons and conrods. Everything else needs to be binned and redesigned from scratch.

Not that is a bad thing. Then you get porn like this.

[woohoo]

Like taking a real inline, make a new crankcase and crankshart, edit the timing and voila, a V8 on the cheap.

How on earth is making a new crankcase and crankshaft considered on-the-cheap?? The crankshaft is probably one of the most expensive parts on the engine.

Not to mention, if you go down this road the only thingd you can use from the whole 4 cyl engine is the head, pistons and conrods. Everything else needs to be binned and redesigned from scratch.

Not that is a bad thing. Then you get porn like this.
...

I did not know it was the most expensive.

It will save you the R&D money though...

Those Hayabusa V8 are awesome 450hp from 2.8 liters and a weight of less than 100kgs.. Me wantee [-o<

[Formula None]

Alternatively you could make V-8 from a V-twin, if your original idea does not provide enough of a challenge.

[youtube]http://www.youtube.com/watch?v=7E6KglXP ... r_embedded[/youtube]


http://thekneeslider.com/archives/2010/ ... v8-update/

[flynfrog]

inline 2 double crank

[Formula None]

I'll see your double crank twin and raise you a 12 rotor Wankel.

[flynfrog]

[youtube]http://www.youtube.com/watch?v=6ratfuML9QA[/youtube]

[Formula None]

I see.

142 L 42-cylinder Liquid cooled 6 row, 7 cylinder per row diesel radial engine. Backed up by the 500 cylinder German Traktorwaffe.



[youtube]http://www.youtube.com/watch?v=buLIk1IWcbk[/youtube]

Your avatar works great for this, btw.

[riff_raff]

woohoo,

"Is it possible?"

Yes.

Is it a good idea?

Not unless you have money to burn.

As an example, lets say you choose to combine two 2.1L Honda S-2000 I-4's to make a nifty 8,000 rpm, 480hp V8. The only things you could salvage from the donor engines would be the heads, valvetrain, pistons and rods. You would have to make a crank, block, front end cam drive with oil and coolant pumps, intake, exhaust, ignition system, and flywheel with starter. Making those parts, plus the donor engines, plus all of the dyno work to map the fuel and ignition systems, would easily cost in excess of $100K.

For about $95K less, you can buy a 500HP 350ci V8 Chevy crate motor. It will be about the same physical size, but will be a bit heavier. If you want its exhaust to sound as cool as the $100K Honda hybrid V8, you can always put a crossunder header on it.

The upside with the Chevy is that it will have a way fatter torque curve than the Honda.

riff_raff

[tok-tokkie]

It has been done several times with motorcycle engines. Drysdale do it http://home.mira.net/~iwd/

You do not need a new crankshaft. As in a rotary engine, one piston has a con rod with a big end. The big end has an eye (many eyes for a rotary). The second piston has a con rod connected to that eye. The load on the big end bearing is hardly affected since the firing strokes are separated.

[Martin Keene]

Like taking a real inline, make a new crankcase and crankshart, edit the timing and voila, a V8 on the cheap.

How on earth is making a new crankcase and crankshaft considered on-the-cheap?? The crankshaft is probably one of the most expensive parts on the engine.

Not to mention, if you go down this road the only thingd you can use from the whole 4 cyl engine is the head, pistons and conrods. Everything else needs to be binned and redesigned from scratch.

Not that is a bad thing. Then you get porn like this.
...

I did not know it was the most expensive.

It will save you the R&D money though...

Those Hayabusa V8 are awesome 450hp from 2.8 liters and a weight of less than 100kgs.. Me wantee [-o<

It won't save you the R&D money, because the crankshaft will have to fundamentally change (2 conrods per big end, not 1) and do not underestimate the work involved in getting crankshaft design right...

The one components in an engine you do not mess with is the crankshaft!

[autogyro]

Wankel Rotary doesnt actualy have one.