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Interesting possible engine swap? 3 cylinder Rotax

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clshore Carter Shore
Beverly Hills, FL, USA   USA
Rotax manufacture a line of 3 cylinder 4 stroke motors that are light, compact, and powerful (up to 300 HP).

https://www.rotax.com/en/products/rotax-powertrains/details/rotax-1630-ace.html
https://www.rotax.com/en/products/rotax-powertrains/engine/4-takt/cylinder/cylinder-3.html

These are used in jet-ski, snowmobile, aircraft, and quad applications worldwide.
Over 100,000 units have been delivered into service.
So parts & availability are excellent.

They are available new, but also used:

https://www.ebay.com/itm/2008-SeaDoo-GTX-215-Engine-Long-Block-4-Tec-Rotax-Motor-150hrs-FRESH-WATER/311814401833?hash=item4899962f29:g:pQQAAOSwCU1YuLGS&vxp=mtr

I know folks who have spent $8,000 having their street Spitfire motors rebuilt and hot-rodded.
They did NOT have 300 HP when the work was completed.

With 3 cylinders, the block is shorter than an inline 4 of similar displacement, should be easier to fit in the cramped Spitfire engine bay (no chassis surgery).

Yes, you will have to engineer the transmission, mounts, radiator, etc. solutions yourself.
Same as with most other high powered swap candidates.



Edited 2 time(s). Last edit at 2018-02-12 12:53 PM by clshore.

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spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Carter,
Interesting, but I figure the height of the swap candidate is the one that makes or breaks the swap. That is, of course, unless a big lump of engine sticking out of the bonnet is acceptable.
All the best,
Paul

Roy Avatar
Roy roy o
Marietta, GA, USA   USA
no torque

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513031 by spitfire50 Carter,
Interesting, but I figure the height of the swap candidate is the one that makes or breaks the swap. That is, of course, unless a big lump of engine sticking out of the bonnet is acceptable.
All the best,
Paul

Spitfire motor is approx. 25" high, from sump to top of the valve cover breather.
I've measured inside hood clearance about 27", from bottom of the frame rail to the inside surface of the hood at the center, right above the rack.

Rotax Bore = 100 mm, stroke = 65-75 mm depending on model

From the pictures posted of bare blocks, and using the bore dimension to scale, I estimate the Rotax height is is less 500 mm, about 20".

But the tape measure does not lie, and I'll try to cruise the nearby showrooms next weekend, and see for myself (I live near the gulf coast of Florida).

For me the first thing I look far is vertical clearance above the rack.
Hoods can be opened up, cross members can be relocated, but change the rack location and you change the steering geometry.
Not gonna happen.
A short motor may not even hang over the rack at all. (like a 3 cylinder!).

TheZster Avatar
TheZster Steven Z
SAINT LOUIS, MO, USA   USA
1978 Triumph 1500 "BLK-BRY"
Just sayin: I bought a spit cause I wanted a spit...... along with the trials and tribulations associated with it..... I'm a firm believer that - with care and judicious rebuilding - I can get her to the limits of her street capabilities (ie:: handling, reliability, looks) by working on what Triumph provided....

If I wanted a "frankenspit".... I would figure a way to slip a small supercharged V-8 into her, complete with needed hood bulges/scoops/etc.....

Guess that's why god created chocolate and vanilla.... different folks - different strokes.....

Ya'll have fun....

Z

Lizzard d id
san jose, CA, USA   USA
In reply to # 1513038 by TheZster by working on what Triumph provided....
So you went back to SU carbs and ditched that nasty old weber ?

dherr2 Avatar
dherr2 David Herr
Adamstown, MD, USA   USA
1972 Triumph Spitfire MkIV "Rat Rod"
Well that would be interesting..... supercharged, high tech and powerful. I agree that it would lack torque but if you geared it for RPM, it would just be a screamer, much like a Honda S2000. If course, the torque is probably much higher than a stock Spitfire,so that is probably a moot point. The only issues I see is you are on your own with a transmission adapter, as most automotive stuff would be pretty hard to mate up with this, plus a large flywheel might dampen the fun. The lack of torque would be good for the stock rear, but a rear end swap probably would be a good idea.

With that said, my turbo Miata swap will cost me around $4,000 all in and make 210 HP and 200 ft/ pounds of torque and overall is much easier of a swap.

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spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
In reply to # 1513034 by Roy no torque

Roy,
It doesn't look that way to me. The 1330 at 115 hp has about 100 lbft torque. Though the engine is only slightly larger than a 1296 it has about 1/3 more torque. You do have to spin it faster to get it though, revs are how the power is produced. With around 100 hp at 5000 rpm and 115 at 7250 it isn't "peaky".
All the best,
Paul

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513038 by TheZster Just sayin: I bought a spit cause I wanted a spit...... along with the trials and tribulations associated with it..... I'm a firm believer that - with care and judicious rebuilding - I can get her to the limits of her street capabilities (ie:: handling, reliability, looks) by working on what Triumph provided....

If I wanted a "frankenspit".... I would figure a way to slip a small supercharged V-8 into her, complete with needed hood bulges/scoops/etc.....

Guess that's why god created chocolate and vanilla.... different folks - different strokes.....

Ya'll have fun....

Z

I've been a Spitfire owner, mechanic, builder, racer, etc. since 1968.
I've owned at least 25 of them, from Mk I to 1500, and still have 6.
As a young man, Spitfires were my daily drivers.
I have suffered just about every failure and mishap you can have, and have fixed them all too.

Fact is, there are no 'small supercharged V-8' that can just be 'slipped in' to a Spitfire.
The Spitfire is like a Lotus Elan for the masses, with a similar basic philosophy of minimalism.

I can relive those simple early days of driving my Spitfire any time I want to, .. I still have one Mk II purchased in 1971.
But having driven a Spitfire in competition, I also know that there other driving experiences that a Spitfire is capable of.
I have the luxury of several choices that are not mutually exclusive.

So yes, I understand and cherish that purity of the original machine.
But I will have my cake, and eat it too, thanks.

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Voda2000 Avatar
Voda2000 Andrew McMillan
Winnipeg, MB, Canada   CAN
There are is pretty interesting engines out there for sure. I’ve got a 500cc Yamaha motor that makes 80hp. The problem is it does it at 11500 RPM. Not exactly great for in a car.

Since this motor is for a marine application I’d be worried about the cooling for a car application. It might also have a really narrow power band.

I’m more familiar with Rotax engines in snowmobiles but their power band can be very narrow as the use a CVT to keep it happy.



1978 Triumph Spitfire

racer490 Jerry Bryant
Palm Harbor, USA   USA
They use Rotax engine in SCCA racing for the Formula 500 class. Got my SCCA license in one. They used to use Kawasaki's.

Greg1835 Avatar
Greg1835 Greg S
Rudolph, WI, USA   USA
Rotax 4-cycle AC engines have something like a 1200 hr. TBO. Plus their parts aren't cheap. May as well just buy a Scorpion - although for the price of 1 of those, I could have 3 or 4 pristine Spits.

ExPatBrit Avatar
ExPatBrit Mike W
Redmond, WA, USA   USA
1200 hours is not so bad translates to 30000 miles that would be about 10 years driving for my car.

Roy Avatar
Roy roy o
Marietta, GA, USA   USA
Paul - your right ! Those numbers look good for our cars . I was thinking of the 440 & 500 cc 3cyl engines you had to rev like crazy to get power . Now I want one ! Lets make a group buy for $1 k each . Roy

clshore Carter Shore
Beverly Hills, FL, USA   USA
Plus the Rotax motors are remarkably light in weight.
Most high performance motors are very maintenance intensive.
I kept a G PROD Spitfire in good nick for nearly 10 years, so I speak from experience.
I don't think a hot rodded Spitfire making 100 HP would come even close to 1200 hours TBO.
And many of the parts required are neither cheap nor common, often being hand made or hand fitted.
Price fully ported/polished Spitfire head, a lightened, balanced, nitrided crankshaft, or a set of lightweight rods or pistons.

There are however some inexpensive, reliable, and commonly available alternatives, if you are willing to settle for 'only' 170 HP.
More on that at a later date.

Carter

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