[JBLasVegas]

This should be in the engine change forum, but... Whatever!!
Last weekend I got a ride in an old 240 with a Mazda Rotary engine change.
Here in Las Vegas, there is a lot where there is an impromptu car show.
There was this dilapidated looking two door Volvo there with the hood up, and I couldn't resist taking a look.
Well, to make a long story short... the dilapidated part took a back seat once I coerced the owner to take me for a ride... East on Sahara to Maryland Parkway.
The inside of this old Volvo was flawless, and the owner said that he wanted to get it all put together before the paint.
He said that he spent two years putting this Mazda Rotary conversion together... and you couldn't believe the acceleration.
My God!!! It was phenominal!
I still can't believe it.
Forget the Ford engine conversions... this conversion was just "In(blanking) credible!!!

Sorry, George if I posted in the wrong place... but I couldn't believe the workmanship of the conversion.
He said that the actual big problem was the linkage between the transmission and the original placement of the Volvo shifter.

Converse... eat your heart out.

This is a really SWEET conversion.

I actually got to drive this machine, and I love it.
No two ways around it... this is the engine conversion for the 21st. Century.

 

[gdill2]

Re: I Meant To Post This Yesterday, But... Whatever... It Might Be In The Wrong Forum (JBLasVegas)

Get the guy to sign up on Swedespeed so we can see some pics and pick his mind.

George Dill

 

[John2x240]

Re: I Meant To Post This Yesterday, But... Whatever... It Might Be In The Wrong Forum (gdill2)

It would be a good swap. Lighter and shorter engine, and sits low for better weight distribution, no valves or connecting rods to give trouble, easy to mod, and smooth in any rev range. The main point to watch is the oil injector pump and lines to lubricate the rotor seals, but that can be resolved by using mixed gas. The other drawback is weak torque at low revs, but hey, those suckers just love to run at higher revs anyway. It would be nice to know which engine he used and what mods if any.

 

[RearWheelPaul]

Re: I Meant To Post This Yesterday, But... Whatever... It Might Be In The Wrong Forum (JBLasVegas)

Rotaries don't have enough torque.

I'm not sure about the superlatives concerning acceleration. Folks frequently (and incorrectly) equate noise and speed. So I'd want to see some numbers before believing such claims.

As for the low center of gravity potential, it's a bit absurd given the chassis that such an engine is going into (240).

Thanks, but I'll stick to B6304F (which is a very sweet set-up) or a V8 (a bit agricultural but it gets the job done) conversions.

 

[JBLasVegas]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (RearWheelPaul)

Noise?
Have you ever heard the pistons wanting to change bores at 20 MPH in first gear on a stock four banger Volvo? Talk about noise. My 1 - 2 shift usually comes at around 12 MPH just for that reason.
Actually, there was far less noise than I'm accustomed to... and reaching 50 MPH in second gear without any fanfare was something that I definitely wasn't expecting.
The engine came out of a 2008 RX-8 that was stolen and then mostly torched.

 

[RearWheelPaul]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (RearWheelPaul)

I did some basic research and calculations concerning this mod:

The engine in a 2008 RX8 produces 159 lb-ft of torque @ 5500 rpm. A stock B230F produces 136 lb-ft @ 2700 rpm. Analysis: You probably won't notice any difference in engine torque until the B230F starts to run out of cam and the RX8 finds it's equivalent power band. The crossover point will be at about 4000 rpm +.

The total engine weight of a Mazda 13B rotary is 278 lbs. According to factory figures, a spec B230F weighs between 308 and 330 lbs. A 30- 50 lb weight savings is nothing to sneeze at. But as the figures below show, the impact on weight distribution is pretty small:

Stock Weight - 2960 lbs (1991 244 w/B230F engine and M47II transmission + aircon)
Stock Weight Distribution - 53/47
Stock Front Axle Weight - 1563.5 lbs
Stock Rear Axle Weight - 1386.5 lbs

New Weight - 2910 lbs (I'm assuming a 50 lb weight loss, thereby giving the Mazda the benefit of the doubt)
New Weight Distribution - 52/48
New Front Axle Weight - 1513.5 lbs
Rear Axle Weight - 1386.5 lbs

These figures assume that there is no additional weight gain from the Mazda 6-speed over the Volvo 5 speed. As both units are made from aluminum, I'm clearly giving the Mazda transmission the benefit of the doubt here.

There is the issue of mounting. Rotaries are dimensionally smaller, so there's going to be a C of G advantage. Given the layout of the 240, this advantage will be very minor overall.

Without going into a lot of details on gear ratios, I will say that the 1-5 cogs on an RX8 tranny are quite similar to that of a Volvo M47 box. So unless the Volvo's Dana rear axle ratio was changed from a 3.31:1 to something like a 3.73:1, the Mazda rotary engine would have quite a time using its 159 lb-ft of torque to move this 3000 lb sedan.

I have no doubt that this mod was well done. I have no doubt that the OP really liked the feel of the car.

I do, however, doubt that this mod transformed a 240 into something really special. You normally need two things to do that: cubes (big motor) or psi (turbo).

FWIW...

 

[Taleof2Bricks2]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (JBLasVegas)

Quote, originally posted by JBLasVegas »

...The engine came out of a 2008 RX-8 ...

Even in the 'turn-key, performance car' it was intended for, this is an underpowered engine, and disappointing, at best (don't ask me how I know).

I initially considered a V8 swap (down the road) for my 244, but I have my eyes on IPd Cameron's turbo conversion project as a more likely scenario, if this ever happens.

Still, nice to hear when someone takes the road less travelled http://********************/smile/emthup.gif . At the SCVCOA show last November, there was a 242 with an S60R motor in it. There were a few V8 conversions, but it was nice to see a 'Volvo on Volvo conversion'.

Modified by Taleof2Bricks2 at 11:58 AM 4-5-2009

 

[John2x240]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (JBLasVegas)

Quote, originally posted by JBLasVegas »

Noise? Have you ever heard the pistons wanting to change bores at 20 MPH in first gear on a stock four banger Volvo? Talk about noise. My 1 - 2 shift usually comes at around 12 MPH just for that reason. Actually, there was far less noise than I'm accustomed to... and reaching 50 MPH in second gear without any fanfare was something that I definitely wasn't expecting. The engine came out of a 2008 RX-8 that was stolen and then mostly torched.

I'm not sure that the Renesis engine was the best choice unless it was really cheap. From what I hear Mazda leaned out the fuel/oil mixture to get better emissions numbers, but that had a negative effect on the life of the apex seals, although I think that the ECU can be tweaked to get a richer mixture. Without going searching for numbers, I'd think that a 13B even without a turbo would be a good choice; a street port job with RB headers and exhaust and something like a Weber DCOE 45 should give somewhere in the region of 160(+) hp without a loss of driveability. Also, to get the best out of the engine, seeing as how the red line would be up around 7000+ RPM, you'd need rear end ratio of around 4.10(+):1, but I don't know if this could be had from stock 240 crown wheel & pinion sets.

 

[RearWheelPaul]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (John2x240)

Quote, originally posted by John2x240 »

a street port job with RB headers and exhaust and something like a Weber DCOE 45 should give somewhere in the region of 160(+) hp without a loss of driveability.

You can get that pretty easily from a B230F. Change the cam, port and polish the head, remove the MAF screens, and clean-up the throttle body will get you 150 bhp. Add a good set of custom headers and a free flowing exhaust, and you should see 155-160 bhp.

The torque curve on such modified B230F engines remain very flat. Peak torque (140 lb-ft) comes in at 2900 and remains until 5700 rpm.

Quote, originally posted by John2x240 »

Also, to get the best out of the engine, seeing as how the red line would be up around 7000+ RPM, you'd need rear end ratio of around 4.10(+):1, but I don't know if this could be had from stock 240 crown wheel & pinion sets.

IIRC the Dana 1031 fitted to 240s can be fitted with any of the ring and pinions from the following applications:

3.31:1 (stock on 240 late model 5 speeds)
3.54:1 (stock on 240 late model automatics and some early model turbos)
3.73:1 (stock on 240, 740 late model automatics and some early model turbos)
3.91:1 (stock on some 240, 740 late model automatics)
4.10:1 (stock on some late model 700s fitted a B2304F with AW72 automatics)

 

[John2x240]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (RearWheelPaul)

I found some HP numbers for 12As and 13Bs with various Weber and Holley carbs here: http://www.racingbeat.com/FRmazda1.htm . A street port on a rotary is a very mild porting job, and for the equivalent of a similar port and polish and a performance cam on a piston engine you'd be looking at a half-bridge port, so the HP numbers would be in between a street and full bridge port, and street driveability would still be OK. So, then, for a 4-port 13B with a Weber 51 IDA you'd be looking at around 215HP, and for just a street port with a 48 IDA you'd get around 185HP, so I guess I was a little low for my first estimate. My 12A bridge port with just a cleaned up and re-jetted Nikki gets close to 200 HP with a fresh engine, but the idle's a bit lumpy for street use and it needs to idle at about 1200 RPM or it could stall with a cold engine. I still think a rotary could be a good swap except for having to adapt the driveline.

 

[RearWheelPaul]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (John2x240)

That sounds pretty good. What sort of torque figures are we looking at for these mods?

 

[John2x240]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (RearWheelPaul)

I don't have the torque specs, but they'd be pretty close to the HP numbers, and higher up the rev band too. I'll see if I can find any torque specs when I get time.

 

[RearWheelPaul]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (John2x240)

Quote, originally posted by John2x240 »

I don't have the torque specs, but they'd be pretty close to the HP numbers, and higher up the rev band too.

They're likely to be somewhat lower, as pumping losses will grow with revs. But you're right in saying that peak torque will be achieved at higher revs.

The bottom line is that you'd have to rev the living $hit out of the engine in order for it to do anything.

Engines such as these do very well on the track where there are few starts and stops. Driving them around town is frequently a chore. Ditto on the highway where the combination of low torque and low (numerically high) final drives requires one to keep the revs very high.

 

[John2x240]

Re: I Meant To Post This Yesterday, But... Whatever... It Mig ... (RearWheelPaul)

The beauty of a rotary is that it's designed for high RPMs; there are no reciprocating masses so there are fewer internal stresses, and at higher revs the apex seals work better through centripetal forces forcing them out against the rotor housings, thus giving better sealing in the combustion chamber. The only issue with continually running higher revs is that the apex and side seals wear a little quicker, which will eventually lower the compression. And this becomes readily apparent on start-up as at the lower cranking speeds the engine will get gradually harder and harder to start, so unless one is a complete idiot, the engine is not operated up to the point where an apex seal could fail completely and cause internal damage ... no dropped valves or wrist pin, rod, or bearing failures here, and therefore no holed engine blocks. The downside is lower fuel economy and more emissions junk on the intake and exhaust systems to control NOX and particulate emissions.