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Interesting possible engine swap? 3 cylinder Rotax

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carChips Avatar
carChips Victor Harnish
Kelowna, BC, Canada   CAN
1933 MG Magnette
1973 Triumph Spitfire 1500 "Chip"
1989 GMC Sierra 1500 "Bush Truck"
I know a few sledders, and they are already planning their spring rebuilds and there is 20 feet of snow in the hills.



'S all for now
Vic

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Peter-K Peter K
Central, ME, USA   USA
F500-Rotax and AMW, Older F440 class was Kawasaki powered. I used to run a Zink Z22 with an AMW 2-Stroke-International purpose built 500 for FMod autocross. It was a bullet and a blast!

Greg1835 Avatar
Greg1835 Greg S
Rudolph, WI, USA   USA
In the watercraft, that 300 h.p. 1630 get about 6 mpg. Better plan on a bigger gas tank as well.winking smiley

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513306 by Greg1835 In the watercraft, that 300 h.p. 1630 get about 6 mpg. Better plan on a bigger gas tank as well.winking smiley

That, or a lighter right foot ...

A hull going through water requires far more power than a vehicle rolling on tires and passing through air.

The watercraft is direct drive, has no gearbox and at steady 50 MPH is WOT at max RPM.
The car at steady 50 MPH will be in top gear, perhaps 2000 RPM, at part throttle.

Voda2000 Avatar
Voda2000 Andrew McMillan
Winnipeg, MB, Canada   CAN
In reply to # 1513340 by clshore
In reply to # 1513306 by Greg1835 In the watercraft, that 300 h.p. 1630 get about 6 mpg. Better plan on a bigger gas tank as well.winking smiley

That, or a lighter right foot ...

A hull going through water requires far more power than a vehicle rolling on tires and passing through air.

The watercraft is direct drive, has no gearbox and at steady 50 MPH is WOT at max RPM.
The car at steady 50 MPH will be in top gear, perhaps 2000 RPM, at part throttle.

Have you been able to see a graph of the torque curve? I’m wondering how much it would actually produce at the lower end. You wouldn’t want to have dump the clutch at 4000 rpm just to get rolling.

I know the scenario is a little different because of the CTV but the Yamaha engine I referred to in an earlier post doesn’t start to produce enough power to move the snowmobile until 3500ish rpm and my setup is at 4200rmp before the clutch closes. Ok for a race car but would be not too streetable.



1978 Triumph Spitfire

clshore Carter Shore
Beverly Hills, FL, USA   USA
Rotax sells different versions of these motors tailored for different markets and applications.
Watercraft, aircraft, snowmobiles, ATV quads, etc.

Different horses for different courses ...

joppamoto Mark R
Crestwood, KY, USA   USA
I should have looked at the engine that you referenced. I was thinking that you were considering a Rotax 2 stroke. That 4 has much better possibilities. Someone needs to try this.



Edited 1 time(s). Last edit at 2018-02-14 07:33 PM by joppamoto.

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dherr2 Avatar
dherr2 David Herr
Adamstown, MD, USA   USA
1972 Triumph Spitfire MkIV "Rat Rod"
They are a neat engine and quite powerful but probably not a good choice for our cars.... the best engine swaps already include a transmission and are set up for RWD from the factory and are compact enough to fit the limited space. Mine has taken some time to figure out, but will check all the boxes and make more than enough power for my needs. It also helps to have an engine set up for automotive use, since as already been mentioned, the torque curve is better suited for driving, verse a snowmobile or watercraft engine that can scream at 8,000 or more driving a CVT or waterpump. I had considered the Honda S2000 for my car, but the combination of low torque, and twice the cost of my Miata drive train sealed the deal. The S2000 drivetrain promises 240 HP, but that is 8,300 RPM with a torque peak of 155 at 7,500. While that sounds fun, the reality is the engine is not that strong unless you rev it hard all the time. For less than 1/2 the price, I will have a Turbo Miata 1.8 with a 6 speed with 225 HP and almost 200 torque, which will be much more drivable as the power will start right at 2,000 and go all the way to 7,300 rpm.

With that said, anything can be made to work with enough time and money, but most of us on this board that would consider an engine swap (and have the skills to do most of it themselves) are looking for solutions that can be reasonably made to work, so the proven Toyota 4AGE, Honda F20C, Mazda BP (Miata), 12 and 13B rotary, Ford 2.3 and a few others all offer an upgrade that can be done in the home garage with reasonable skills. You still have to figure out the rear diff question or you will forever drive around wondering when it will fail.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1513397 by joppamoto Keep in mind these engines have a pressed multiple component crankshaft. These do not like shock loads (dumping the clutch) because of the risk of slip, and going out of phase, or balance. They are generally used with a CVT, propeller, or Impeller which have limited shock loads. Also because of being made up of many pressed pieces, they must be sent out to a specialist with the proper equipment to press, and align the assy instead of just replacing inserts. I have had this done on two occasions for bad rod roller bearings. Not cheap. Also being a 2 stroke they make most of their power in a limited range. The power valves used on some help with this, and of course porting and pipe type can change the power delivery. I would love to see someone try this in a Spitfire, but have my doubts that it will work to their long term satisfaction.

The Rotax big triples are SOHC 4 strokes with 4 valves/cylinder, and use conventional crankshafts, bearings and rods:

https://www.ebay.com/itm/Sea-Doo-4-TEC-185-Crank-Shaft-OEM-GTX-Wake-Limited-SC-RXP-RXT-155-215/122512675246?hash=item1c865311ae:g:LdEAAOSwH09ZJJz3&vxp=mtr
Z4AAOSwZQxW4MZC&vxp=mtr" target="_blank" >https://www.ebay.com/itm/SEADOO-4-TEC-FULLY-rebuilt-CRANKSHAFT-and-RODS-with-NEW-rod-bearings-ROTAX-1503/201790909875?hash=item2efbacedb3:ggrinning smileyZ4AAOSwZQxW4MZC&vxp=mtr

With 3 cylinders, they can use 3 mains, with rod throws at 120 degree spacing.

The cases are split at the crank, so there's no separate oil pan

http://www.ebay.com/bhp/seadoo-4-tec-engine

You can see the balance shaft that runs parallel to the crank, driven at engine speed by gears at the front.



Edited 2 time(s). Last edit at 2018-02-14 06:13 PM by clshore.

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GeorgeOhr Nonya Business
Yes, confused, USA   USA
In reply to # 1513037 by clshore (I live near the gulf coast of Florida).

Interesting. My sis lives in Tampa and I may be heading that way in the future. No idea when that trip is going to happen yet; she just left here.



Edited 1 time(s). Last edit at 2018-02-14 08:40 PM by GeorgeOhr.

clshore Carter Shore
Beverly Hills, FL, USA   USA
Sure, I'm about 80 miles north of Tampa.

GeorgeOhr Nonya Business
Yes, confused, USA   USA
I'll keep you posted wen i head that way.

2190 Dan Smith
Santa Fe, NM, USA   USA
The Rotax sounds interesting. Wondering about how/what transmission would work. I am going to swap the drivetrain in a Spitfire I picked up recently. Would like to try Chevy 3.4 V6 and T5 trans. like I did in my TR250. Works great and looks like it will fit without too much alteration, Only problem is finding a high gear ratio differential. Would like to try a Ford IRS like around a '90 Thunderbird but I am totally blind as I can't find anyone who has attempted this and don't know where to begin. I see a lot of info on Subaru 160 swaps but there doesn't seem to be any gear ratios that are high enough. I don't race but like to cruise highways and also like quick jaunts on mountain roads so a tall highway gear is best.

Maybe I should consider a total Miata swap. I would prefer to not alter my bonnet. Curious- How are the Miata swaps on the highway? The 180 hp Turbo 6 speed sounds tempting. May be hard to find a turbo in NM though.

Thanks.

Manana Avatar
Manana Steve Wten
Thornhill, ON, Canada   CAN
I too wonder the drive-ability off-the-line of one of those engines. Getting 1700 pounds rolling is different than what about 1/4 that? I’m guessing it’d be fine once moving, but not sure about the start.

Dan, I think one of the reasons you don’t see much about the T-bird rear end is that I believe it is quite large, 8.8” if I’m not mistaken, or 223mm. I don’t think with a 1700/1800 lb car one could ever get enough traction for that to be required. And for the wider track of the suspension, components would need to be greatly modified, so, might as well start from scratch there.

Considering the R160 is 60mm smaller and pretty robust, it really is a great candidate.
Because I want, think I need, a short nose diff, I’m looking at the R200 for now. But also considering a BMW version – Allan emailed me lately about my website and put that bug back in my mind. The older Small Case Diffs were 168, Later Medium Case Diffs were 188, and the Big Cases were 210. He specifically mentioned the 188 and I think it is a good candidate, looks like 3.46 gears are not uncommon.

As for the Miata swap on the highway, depending on the diff it would be much like the factory Miata. Although it may rev similarly, or a touch lower, at least the engine doesn’t sound like it’s going to blow up. In my case though, I’m running 3.27 gears right now (GT6 diff) and it is fabulous on the highway, I think I’m turning about 2800 at 115 kmph (71.5 mph). With the slightly lighter weight of the Spit it’s super.
Although still a blast at AutoCross I am looking to move to the 3.5 range in the diff as possibly the best overall ratio in my car.

A number of us have done Miata swaps without altering the bonnet, that was a big priority for me.
Check out Dave’s thread, really nice work….https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/rat-rod-1972-mk4-triumph-spitfire-project/132550/page1/

Or my site for how I got mine on the road in 3 months….http://stevew10.wixsite.com/spit16/blank-d4a4m
I also have a links page with a number of other swaps.



Steve
http://stevew10.wix.com/spit16

dherr2 Avatar
dherr2 David Herr
Adamstown, MD, USA   USA
1972 Triumph Spitfire MkIV "Rat Rod"
Dan, while GM V6 swaps have been done in Spitfires, there is less room for a T5 in the frame and exhaust routing will be an issue as well. There is more room in the TR cars for a V6-V8 engine (I have a Rover V8 in my TR4A). For that reason, I would recommend looking at a Miata engine and transmission as it can be made to fit under the bonnet and if you swap the diff, you can handle the power. As far as finding a turbo Miata, just build one, there are tons of info on the subject, I have built mine up from scratch, not that hard to do. The big issue with a turbo is that you will need to get rid of the stock ECU and go with an aftermarket ECU so you have full control over the fuel and ignition maps. Again, not that hard and lots on the internet on the subject.

In regards to the R160, it is a clean solution, but there are many little pieces that all have to be there to make it work correctly. Some of the parts I used (Rotoflex suspension, MGF/Rover/Subaru custom CV axles, Cast aluminum rear diff cover, etc... ) are difficult to get here in the States and since Cantley is no longer selling the CV axles for the GT6, you need to become friends with a good machinist to go this route.

It may be easier to look for alternative solutions such as the BMW units Steve is considering, but you will still be creating your own CV axles and/or creating your own rear suspension.

I have not driven my car yet (unlike Steve), but will be reporting on it later this Spring. Since you have already done a engine swapped TR250, you know what is involved, so go for it!

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