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First, hello RX7 guys! Love your cars, especially love your motors!
Second, mods, if this thread is off base I apologize, I'm new here.
WHY IN A VANAGON???
Because the diesel motors are notoriously bad, unreliably producing 50 horsepower for a 4000 pound vehicle. Additionally, the gearing in diesel vanagons is insane to accommodate such an awful motor. With the factory 4 speed, 1st gear hits the diesel redline of 4800 rpm at 9 mph. 4th gear redlines at 68mph, but with 50hp a diesel vanagon will never get there anyway.
The transmissions aren't built to handle a lot of torque. But a van could certainly use the power to get up hills without causing traffic jams.
The engine bays are tiny and flat, so there aren't many engines that fit well in a vanagon.
Also, I think this swap would be absolutely hilarious, and there would be no better way to take advantage of my CA smog-free status.
WHAT ARE YOU DOING HERE???
I'm looking to start research into what this swap would take, and I need to know what to start looking for. I'd love some help from rotary experts that have put wankels in places where they don't belong.
Am I in the right place?? - if anybody has suggestions for build threads/sites/forums where I'd find good info on rotary swaps in general, I'd love to hear them. I've got the Vanagon side covered, but I'm about to dive headfirst into general rotary research.
Engine Models - I'm not looking for monster power (150 hp is plenty, 275 would be too much) and want to keep a bit of a tight budget. This engine will be living between 4-5k rpm. I'm expecting that my best bet will be either a Renesis from an RX-8 or a turbo S4 from an FC. I'd love to hear why I'm wrong.
DON'T FEED THE TROLL!!!
No, I'm serious, here's the van:
You wouldn't believe how long it took to get up this hill.
This van won't be ripped apart any time soon, but I want to start my research and Craigslisting so I can hit the ground when my diesel stops running. Any help is appreciated!
Welcome.
What year is your van?
IIRC, states like California have strict laws about engine swaps (engine must be same year or newer than the car, I believe.)
At least I know that I'm not the only guy doing a Rotary swap into a diesel VW..
But I need a refresher.
The older Vanagons. Were they longitudinal or a transverse setup?
I'm doing a MK2 golf, and have some ideas on how to do a FWD setup. But I'm not using the VW gearbox.
The only really practical reason is that diesel vanagons have very low range transmissions. As I said in my first post: 4800rpm at 68 mph. Throwing in a Subaru swap (or a normal vanagon waterboxer, which would be my flat-4 preference) would require either rebuilding my transmission with higher range gearing, buying a new 5 speed, or putting in a taller diff and throwing tons of stress on the transmission. I expect that a rotary would actually work pretty well with the stock gear range.
The bottom line, though, is that a decent flat-4 swap is totally doable and probably price-competitive with rotary engine, but sounds less fun.
OK I know where your at now.
I have seen a few, just never thought of it.. lol
That being said. If you want to run your factory transmission, your gonna have to open it up anyway. You'll need to have a custom pilot shaft made to run the mazda flywheel. You also have to be aware of the starter location in respect to the mazda flywheel.
I suggest the 12a if you proceed in this, as the 13b is just that much longer. It could cause fitment issues. (I tried, a 13b is to long for my application).
But it's all doable with some fab, and a welder.
That being said. If you want to run your factory transmission, your gonna have to open it up anyway. You'll need to have a custom pilot shaft made to run the mazda flywheel. You also have to be aware of the starter location in respect to the mazda flywheel.
I suggest the 12a if you proceed in this, as the 13b is just that much longer. It could cause fitment issues. (I tried, a 13b is to long for my application).
But it's all doable with some fab, and a welder.
Good point on the pilotshaft/flywheel/starter combo. I'm basically assuming that I'm gonna have to figure that out on my own for any rotary, given that this seems to be mostly uncharted territory. I'm curious what rotary bug builds have done; they should be relatively similar to my setup.
As for the block length, I'm fairly sure a 13b will fit ok. There's more space back there than you'd expect since the radiator is up front.
Still, 12a could be a good idea. I haven't looked much into those - were all but the Japanese turbos were carburated? Would a low-cost rebuild be able to raise the rev limit above the stock 7k (kinda critical on a 4 speed trans)?
Good point on the pilotshaft/flywheel/starter combo. I'm basically assuming that I'm gonna have to figure that out on my own for any rotary, given that this seems to be mostly uncharted territory. I'm curious what rotary bug builds have done; they should be relatively similar to my setup.
As for the block length, I'm fairly sure a 13b will fit ok. There's more space back there than you'd expect since the radiator is up front.
Still, 12a could be a good idea. I haven't looked much into those - were all but the Japanese turbos were carburated? Would a low-cost rebuild be able to raise the rev limit above the stock 7k (kinda critical on a 4 speed trans)?
7k... LMFAO!!
Even with an extended street port on a 12a you'll be singing south of 10k. Peripheral port motors can go past 12k.
They rev like crazy!!
But most of the 12a's are N/A carbureted engines. Some of the late ones were turbo fuel injected mills.
The 12a is cheaper to buy, and more readily available. (Though some parts are getting harder to find). I'm a big 12a fan.
13b's are going for big bucks these days. But can make big power if built right, with the right turbo.
It all depends on how deep your pockets are?
But as far as adapters, and stuff go. There are kits to mate Rotary's to the bug transaxle. Just Google it..
So, this 9k+ rpm 12a... What kind of reliability would you expect from something like that? Is that just burning through apex seals every 40k miles, or is that actually a durable setup with a rebuild using modern materials? To keep power up that high, am I heavily porting the intake/exhaust and costing myself low RPM performance? Could stock carbs supply the fuel+air for that (extrapolating from stock torque here) 170ish hp setup, or would that require a totally upgraded fuel system?
So, this 9k+ rpm 12a... What kind of reliability would you expect from something like that? Is that just burning through apex seals every 40k miles, or is that actually a durable setup with a rebuild using modern materials? To keep power up that high, am I heavily porting the intake/exhaust and costing myself low RPM performance? Could stock carbs supply the fuel+air for that (extrapolating from stock torque here) 170ish hp setup, or would that require a totally upgraded fuel system?
We'll in your situation, I'd consider the wieght to the gearing.
Your still going to want as much bottom end as it could muster.
I'd shy away from any heavy porting to keep a mid range powerband if your going to stay naturally aspirated.
With a good street port, you could easily hit the numbers your looking for with a 12a.
Add a bit of timing for a mild extended port, and you should be around 170-180hp with a good intake, carb, and header.
I suggest going with the Weber 48 IDA downdraft setup.
With that you would need an electric fuel pump around 5psi, easy to rig up.
Then as far as longevity... Well that's a Grey area IMO.
Even if you use carbon apex seals, and premix your fuel with a good 2 stroke oil. They don't last forever.
They like to rev, and you gotta give it to them. My buddies got a 78' RX7 with a bridge ported 12a. He's right around 7000 miles since the last rebuild, and it's starting to go. (But it gets the ever liven **** driven out of it). With a milder port, it will last longer!
Something you have to consider as well.
Here's my .02 A couple years ago I was playing with the idea of a Gen2 13B in a Samurai.
The Samurai comes with a 1.3 liter engine but slightly underpowered. I wanted the rev happy-over 100hp rotary for coolness and to continue my rotary love.
The turbo RX7s from the 80s used the stronger transmission, and it has a removable bellhousing. The Mazda b2600 pickup from (correct me here) 87-88? used the same strong transmission but set up for 4wd with the short tailshaft for the transfer case. And it also had the removable bellhousing. My plan was to take the 13B bellhousing off the turbo trans and bolt up to the 4wd transmission/transfer combo to have a lovely setup using only factory parts.
Life ended up changing and that project went to the way back burner, but the idea and knowledge didn't bleed out too far I don't think
Any of this may or may not be of help, but I hope its the former and can open up some ideas for you.
05-12-17, 11:27 PM
