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Opeler
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Discussion Starter · #1 ·
Hello,

Since I am new to the board let me introduce myself: I am a 21 year old male college student from central Washington State. I am taking classes to become an IT guy and will be graduating June of 2006. I am currently the owner of a 1983 Mazda RX-7 that is slightly less than stock, it is still NA but just about everything shy of forced induction and porting has been done to it. I procured the car initially as a daily driver because I was moving out of town and needed a car. The price was right and at the time I really didn't care what type of engine was in the car nor did I really understand what a rotary engine was all about. I knew that it consisted of a number of rotors that went around and around and, well you get it, but that was about it. Long story short within these last eight months I have become obsessed with rotary engines and after being introduced to the Opel GT by a classic Toyota Celica owning friend of mine I have quickly become obsessed with the bodies of these cars simply by looking at pictures on the web (I have yet to see one in person, if you live near Wenatchee and would like to give me (and probably my Celica friend) a viewing or ride it would be most appreciated). After I graduate, get a good job, and buy myself a house I am planning on building my “dream car.”

Thus far my “dream car” is a 1972 Opel GT with a 13B-RE street-ported, fuel injected, turbocharged rotary engine with an all wheel drive and a six speed transmission conversion. I plan on using lightened rotors and replacing the engine side housings with aluminum ones. My goal is to keep the weight around or lower than what the stock GT’s are. There are various other ideas I have going around my head but I have the engine and the chassis pretty much nailed down.

This leads me to my question: Would it be possible to do an all wheel drive conversion on an Opel GT? Has it been done or attempted before, if it wouldn't be possible in your opinion please elaborate as to why not? I tend to not take to heart people’s ideas when they simply tell me my idea’s can’t be done while not providing any solid reason why.

Assume money is basically a non-issue. I am planning on spending 20-40k on this project as it will give me more bangs for the buck and pleasure than any overly priced new car ever would. The joy of creating and customizing alone will almost make doing this better than getting any new car, let alone the thrill of driving it after it is completed.

Thank you for your time,
Adam
 

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OPEL-LESS!!!
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2,116 Posts
making an all wheel drive GT surely would be no easy task, you'd probably be pretty much on your own trying to use stock opel chassis to make it a awd drivetrain. to make a 4x4 GT, the easiest most pheasable thing to do would probably be to drop it on a 4x4 truck frame, but then that pretty much prohibits the use of a rotary. theres not much room under a GT for the awd componets, just simply no room for much. bigger transmissions are a problem of fitment in the tunnell, where woudl the transfer case go? getting a look at a GT would be a real good thing before developing to many ideas as space will be your biggest issue/enemy.
 

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I assume by AWD you mean with a viscous center coupling (as opposed to 4wd)? This is more in line with 'sporting' driving intentions rather than mud-bog style 4wd.

The least expensive parts swap will probably be Subaru-based. The WRX driveline parts (tranny especially) are a bit fragile though when pushed hard. Knowing how low a WRX engine is normally mounted, the rotary wouldn't be a far reach to fit under a GT's hood. However, you would need to fabricate from scratch some new form of suspension...the WRX's long-travel struts would simply poke through the fender line of a GT by numerous inches. So perhaps a custom upper/lower a-frame suspension conversion with inboard-mounted coilovers would be appropriate.

Then there's the track width to attend to. Either narrow everything in the driveline and suspension (engine cradle, rack and pinion, a-arms, half-shafts, etc), or widen the track width of a GT by about a foot and add flares. I suspect the car could be pared down to 2300-2500 lbs if you forgo most of the creature comforts. The rotary is without a doubt lighter than a GT engine, but the AWD driveline, larger brakes, chassis reinforcements and larger/heavier tires and wheels will add weight to the car in general.

If you truly wanted a 6-speed transmission, then the WRX STI is the car you're after. I don't know of any other AWD 6-speed trannys that are non competition based being available in the US. A 5 speed should really be sufficient though....

Is it doable? Yes, given the time, money and knowlege, it is.

Feasible? Probably not. If you have to ask the question 'Is it doable?', then you're probably not capable yourself (at least not at the moment, with age comes experience). So otherwise, open your checkbook and be prepared to pay for about a year of someone's time to build it. $40 to $50k is not out of line if you have to pay someone to do the work. If you are a decent fabricator, and luck out with a donor vehicle at the junkyard, and can build your own engine....you could probably do the job for $10-$15k. But it will be labor-intensive and frustrating. Just ask those here who've attempted the 'simple' task of installing an engine from another non-Opel vehicle which was nowhere near as intense a job as what you are planning.

That being said, if you decide to go through with this project, please, keep us informed. I would start measuring GT's up, measure up the rotary, and measure up the AWD driveline of your choice. Then, start your plan of action. It might take 3-4 months of planning to figure everything just right, but better that than scrapping the project halfway through because of some oversight. If you get to this point, I have a GT in my barn, and a WRX in my driveway, so I could certainly take measurements if that would help you out any.

Good luck, and welcome to these forums!

Bob
 

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Member
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2,054 Posts
Welcome

Welcome Adam
I've got a question; When you said you're an IT student, is that Industrial Technology, or Information Technology?

Regarding the 4-wheel drive issue, I need to qualify that I have never performed a conversion of any sort on a car, so here goes: It seems that there have been a number of small automobiles with all wheel drive over the last two decades. If I remember right, one of the guys I used to commute with had a Honda with something called Real Time All Wheel Drive. And it was a small car with typical low clearance of a 2-wheel drive. Also, Audi produced several models I believe. If spending money doesn't scare you (you must not be married yet) salvaging entire drive trains from these and modifing them might be doable, especially if you're major is Industrial Technology and your emphasis or sub-major is on industrial process rather than safety or environmental or construction.

The Talon was 4-wheel drive wasn't it? But I think I remember it sits higher than the GT.

The choice of the 13B rotary is good. Doesn't this 1.3 liter 2 rotor engine in stock form produce approx 155 hp? I'm curious how much increase you can squeeze out of this engine.

And, I think another member here has already dropped a 13B in his Opel GT. It would be interesting to confirm that and find out how it worked. I suspect that if you're willing to move, or forego, air-conditioning, and if you can modify the engine management system so you can delete that air-pump hanging way out on the passenger side, that tiny engine would slide in pretty nicely.

You'll probably get a lot of questions as to why you want 4-wheel drive. Is it because the GT is light in the back and breaks loose too easily in snow? Or because you want to use it off-road? Or just 'cause it would be cool? Personally, if I was driving through the mountains of Central Washington, I would certainly feel more confident with 4-wheel drive.

Again, welcome.
 

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Adam, to add emphasis to what Rally Bob said, and to give you a bit of insight on what it takes to do a non-Opel engine/tranny installation, go to the articles section, engine swaps, and you'll see my 5 phases of a GM 3.4L V-6/T-5 tranny swap. Understand I am not done yet, just documenting as I go. As far as cost, that's still up in the air, reason, I use the same credit card for Opel expenses, Dog show expenses and other expenses as well, so far total is over $30K and I'm not done yet. Time wise, I stated over 2 years ago and am finally getting close to putting it all back together again, after a complete strip and restoration along with the engine/tranny swap. Is it do-able, for me yes, but as everyone will tell you, a lot of fabrication will be needed for more than a couple of reasons. One thing you cannot do is remove the body and put it on another frame, the GT is a unibody and it all needs to be together to work, although you could buy fiberglass parts and put them on a frame, but it just wouldn't be the same. Do us all a favor, please, if you do decide to get on with the project, do like RB said and do a lot of measuring and research. Then if you do wish to continue, finish it. None of us want to see an Opel torn apart then crunched because a project is left undone. HTH.
 

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1450 Seeker...
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AWD,13b turbo in a GT would qualify, as us New Englanders say, as wicked cool. Personally, I've mused about similar swaps, but ultimately reason that it's just too much work. If it seems as though the members of this board are down on such an aggressive swap, it's because we've seen far to many GT's sliced up with the best of intentions, then never finished. So as others have said, if you are going to undertake a project like this, please finish it.

Remember that AWD and 4WD are two totally different animals, both mechanically and performance-wise. About the only thing AWD and 4WD have in common is the fact that power is pushed to all 4 wheels... sort of. AWD insuates that the drive line has a viscous coupling which allows a fair amount of slip between the front and rear wheels. A lot of the newer systems, Caddy, Mitsu, Mercedes, Audi, BMW, Porsche, Subaru (the list goes on) have a power bias to the front or rear wheels, which direct power to the opposite end on wheel slip. This aids in economy and to avoid bogging the motor on tricky launches. Some cars control this process electronically, others do it via fluid pressures. Another added bonus is that almost every AWD car that I know of uses independent front and rear suspension for much better handling.

Now, how does all this apply to swapping into a GT? AWD systems are pretty gosh dern complicated. Factors to consider, locating donor cars (you need a GT, an RX-x, and a AWD donor). Don't forget you need to get all the electronics to play nice with each other. Also, a turbo 13b can huff a surprising amount of power with proper mods. Consider again that AWD is going to stress and twist the car in ways that the GT never anticipated, so some serious stiffening is in order. Might as well go with a tube frame, cut the floor out of the GT and... well you'll be a little closer anyways.
 

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Opeler
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Discussion Starter · #7 ·
I can already tell I’m going to enjoy this board much more than I do RX7club!

First off thank you all for your replies, for the sake of clarity I will reply to each person as necessary separately (if I don't respond directly to you on a point it is probably because I feel I covered it through replying to someone else):

@RallyBob:
Yes, I was interested in an AWD swap (viscous center coupling) and had no interest in doing a 4WD swap.

Would none of the older, smaller AWD cars be a better option? For example the Plymouth Talon TSI, Mitsubishi Eclipse (I forget the letters Talon TSI clone), or a Chrysler Laser (if they made an AWD version)? There's another car one of my professors just have the car's name escapes me at the moment; I'll post it on Monday.

I would be more than happy with a 5-speed but if it turns out to be feasible I will go with a 6-speed. I prefer to start with ideas that most will consider "out there" so that if I work my way back towards the earth I will still have a nifty little car.

I know full well I am not capable at doing a project like this by myself (at present anyway). I honestly would rather not do it by myself. Right now the idea I have is to do a large part with my friend and my uncle and then to have a professional (Pineapple Racing) do all the "scary" porting, tuning, and anything else that I don't feel secure doing. Both my uncle and my friend can fabricate anything for me (it's a "if my friend can't do it my uncle can" sort of deal) so I'm covered on the custom fabrication front and my uncle has been working on hotrods since he was sixteen and has custom built racing boats so a large part of the experience I will be pooling is his.

Thank you for offering to help me with the measurements. I will definitely keep it in mind and I will defiantly keep forum members informed with my projects progress. I assure you if I start this project I will complete it, as I am familiar with the disgust that comes from people destroying these classic cars.

@West Coast GT:
I apologize I didn't realize "IT" was used in reference to any other industry. I am an Information Technology student. No I am thankfully not yet married : ).

The Talon TSI was AWD and was turbocharged.

The naturally aspirated 13B found in anything other than the RX-8 produces somewhere between 135-160HP (HP varied through the years). The RX-8 13B entitled the "RENESIS" produces 238HP out of a 1.3 liter NA engine. The 13b engines I'm leaning towards are the 13B-RE and the 13B-REW both are stock with a sequential twin turbo setup and make 230-235HP and 255HP respectively. The RE comes from the Eurnos Cosmo and has a little more low down torque while the REW comes from the 3rd generation RX-7's and has a little more stock HP. With a mild to moderate street port and a single turbo 300-400+HP would most definitely be achievable I’ve read (weak statement I know if anyone wishes I’ll do some research and post documented cases only) of people with numbers as high as 800HP (though anything past 600HP is pretty rare from my understanding).

AC is nothing to me and so long as I stay out of areas that require emissions testing, or if I find a way around said testing I will be loosing the air pump.

The reason I want to put AWD on the car is to get the power to the ground as well as to improve the handling in under all conditions.

@namba209:
Thanks for the article I will read it this weekend (it's 1:30AM an I'm not quite up to the task right now : ).

@madhatterpdc:
I'm not sure where people got the idea that I was even interested in doing a 4WD swap. If AWD and 4WD are commonly misused out of ignorance or if they can be used interchangeably I was unaware of that.

For donor cars I will hopefully not need a full 3rd Gen. RX-7 or Eunos Cosmo as I plan on getting a j-spec engine and if other parts are needed for the swap if possible I plan on ordering those with the engine or by themselves.

As for the chassis reinforcement, would this not be needed if I kept the car rear-wheel drive, or is this going to be a necessity with any route that involves a relatively large amount of HP/Torque? What is the max HP/Torque the GT's chassis can take in stock form? Can you point me to any examples of GT with a reinforced chassis?

@everyone:
My reasoning behind wanting to go with AWD is to improve my ability to get the power to the ground and to improve my handling abilities. From my understanding thus far I will most-likely have to reinforce the chassis to deal with the power the rotary engine will be putting out so if I can find a feasible way to convert the car to AWD I will do it as the added weight (and please correct me if I'm wrong) will be offset by the front wheels being able to pull me around the corners.

With this car I am looking for an ungodly fast car that will be able to make up for any lack in straight line speed with it's ability to take corners, if I can have just as much fun rain, sun, or snow all the better, if any weight gain can be offset with other features such as AWD that would be excellent.

I apologize for being less than succinct and for jumping around quite a bit; I’m going to blame it on the time (2:10 now). Oh, and apologies to the Moderators for my misplaced post.

Thanks again,
Adam
 

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boomerang opeler
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5,636 Posts
adam if you have access to fau (friend and uncle ) fabricators then why not rebody the RX7 doner with the gt
its how im doing my change to a V12 jag gt
im cutting out the gt next to the inner sill plate and taking off thebody on the jag xjs @ the right width to match the gt [about 2" in from each sill], take 5" out of the floor and prop to get the right lenth and weld all back together
there dont sound any were near as scary if you say it fast :eek:
that way i get all wiring inplace and just have to adapt it to a gt dash
or maybe go right hand drive so i can see to overtake hear :)
 

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boomerang opeler
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5,636 Posts
at last a gt you can do the oil filter change on without a trolly jack:)
 

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Old Opeler
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5,564 Posts
deimox said:
As for the chassis reinforcement, would this not be needed if I kept the car rear-wheel drive, or is this going to be a necessity with any route that involves a relatively large amount of HP/Torque? What is the max HP/Torque the GT's chassis can take in stock form? Can you point me to any examples of GT with a reinforced chassis? Adam
Adam, The reinforcement is necessary because the GT body shell is very light and welded together in one piece - the doors, hood and headlight buckets are the only really seperate pieces. The panel metal is very thin and the chasis sections small by comparison to full-size US cars - made that way deliberately to conserve weight and add performance due to lightness.
This leads to a flexible body shell - so much so that with above about 150 horsepower, rumour has it, that the front and/or rear screens can pop out!

As for examples of strengthened chasis - have a look for "Aero GT" which is a convertible conversion which requires lots of chasis strengthening due to the removal of the roof.
 

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Break the project into Stages

Adam,

Everyone is going to give you an option on how to put a AWD GT on the road. This is mine....

It sounds like you are trying to eat an elephant!! With this in mind, I would break it down into little bites and in stages. This is what I mean.

1st. I would get a donor GT (preferably one with little rust)

2nd. Make the GT strong (Get rid of the rust, clean out all the dirt, fix any wiring trouble) get it to run at stock (or as close to stock as you get it).

3rd. Do the eng. swap to the 13b

4th. Do the AWD swap.

The way I look at it you have 3 major projects. First getting a GT, second swapping the eng, and third AWD swap.

If you break the project down you will be able to enjoy your GT at various different stages and drive it. Then you may decide that you do not need to go on to the next stage because you are happy with what you have been able to do. That way you do not get frustrated with it and leave the GT in mid project.

This is just my $0.02 worth.

Good luck!!! :D
 

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Super Moderator
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deimox said:
Would none of the older, smaller AWD cars be a better option? For example the Plymouth Talon TSI, Mitsubishi Eclipse (I forget the letters Talon TSI clone), or a Chrysler Laser (if they made an AWD version)? There's another car one of my professors just have the car's name escapes me at the moment; I'll post it on Monday.
Adam, the only reason I did not mention the AWD Chryslers/Mitsubishis is the fact that the engines are transversely mounted, and this may create difficulty adapting the rotary engine. That, and those AWD systems are a bit more primitive and as a result the cars are know to be fairly dedicated understeerers.

HTH,
Bob
 

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4ZUA787
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665 Posts
the sweetest thing would be to take a mini cooper s withe the cooper works edition and transplant that powerplant into a gt, that would be killer dude, i mean killer, u would probally require alot of modifactaion to the shifter to locate it properlly but if u could design the front end correctly u would have a light fast little gt, just a dream though just a dream.
 

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boomerang opeler
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5,636 Posts
fwd in an opel aaaaaaararrrrrrrgggggghhhhhhh you will end up wanting a modern euro opel like an astra or vectra and its a cruel thing to do to a country that has still only got rwd opels
they are souless abomanations that put you to sleep
pass the dried frog pills burser
they only make fwd because its cheap its not for your pleasure :(

sorry about the rant and i've got to stop reading pratchett
 

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Detritus Maximus
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2,839 Posts
Adam-

Speaking as a fellow rotary owner, 2nd gens, I offer my congratulations and condolences.

Are you familiar with Rod Millen's awd 1st gen RX7? If not, do a search and see what he did and used.
Although it is not up-to-date technology, it may provide some insight. Since the cars are closer in size than just about any of the others suggested, it may help with thoughts on 'packaging'.

Given the clearance needed, I'd almost say a Manta/Ascona would be a more likely candidate. More room underneath from the longer chassis and the front frame rails cut up fairly high for the front subframe (which also makes fabricating a front subframe and mounting it potentially easier).



Here is a question Bob, or anyone else that might know....
Too much power in a GT will twist the body, that much is a given, but that is when putting all the power thru the rear axle. Does this scenario change if you split the power front and back? If 200 hp (or ft/lbs) going thru the rear axle will twist the body, what happens if you have 100 hp (or ft/lbs) going thru a front axle and the same amount thru the rear?
Or does it ghet worse?
 

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Member
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One more thought

Just another consideration on hp/tq twisting the body. What effect will the switch to a independant four wheel suspension instead of a live axle have on the body?

Darrin
 

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boomerang opeler
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5,636 Posts
little on the body but big on handling
the irs helps keep both rear wheels on the ground and flat so giving much better grip
you can also lose the weak point in the opel packege
the rear diff/ torque tube
 

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Senior Contributor
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903 Posts
opelbits said:
Here is a question Bob, or anyone else that might know....
Too much power in a GT will twist the body, that much is a given, but that is when putting all the power thru the rear axle. Does this scenario change if you split the power front and back? If 200 hp (or ft/lbs) going thru the rear axle will twist the body, what happens if you have 100 hp (or ft/lbs) going thru a front axle and the same amount thru the rear?
Or does it ghet worse?
Opelbits,

I wouldn't be too worried about the twisting of the body. The torque(same torque as measured on a torque wrench) that people are concerned with is applied across the body between the engine mounts in the front and the springs, trailing arms and torque tube in the rear. If you twist the body too much, you risk cracking or even potentially popping the glass out of the body. Rather than what would seem to be the obvious question(how much torque is too much) I prefer to go about this a slightly different way

There is a big difference between how much torque we can supply from the motor and how much we can actually apply across the body. This difference comes from the traction of the rear wheels. If we pick the rear wheels off the ground we'll have nearly no torque across the body. If we attach the wheels to the ground we'll have all the torque that can supplied by the motor. The truth obviously is somewhere in between.

From basic mechanics we learn that torque(unlike power) will increase/decrease though a gearbox. Ignoring the inefficencies of the rear axle, the max torque applied across the body will be equal to the max rear wheel torque divided by the rear gear ratio. No matter how much torque or hp we are making, this will always be true. So, if you can break your rear wheels free under acceleration, you've already experienced the max torque that your setup can apply across the body, no matter how much HP you have. Obviously, wider stickier tires, limited slips and lower gear ratios will increase the torque you will actually be able to apply.

The one thing I have left out is transient torques. If you rev the motor up and dump the clutch you could create a spike in the applied torque for a very brief period of time. However, these transients will largely be absorbed by the engine mounts, rear springs, rear suspension bushings and so on.

Except under very extreme cases, I think it's safe to assume that the rear tires on a street car will prevent anyone from having any problems. I can personally attest that my GT with 9.5" wide racing slicks, torsen style LSD and 4.88 gears will NOT cause any problems even under the hardest racing launches (that one shouldn't be doing on the street). The 4.88s will reduce the torque on the body over the stock 3.44's but the sticky tires and LSD will more than make up for it. I also had no problems with the same tires as above with 4.10s and no LSD. And yes, I can easily break the rear wheels free.

Just my 2 cents worth.

-Travis
 

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Opeler
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Discussion Starter · #20 ·
Hello again, I apologize for the delay in my response; I became busy with end of quarter class work and was waiting for an opportune time to sit down and answer the abundant responses that my thread has received thus far.

@baz
Would re-bodying the donor car still be an ideal way to go about things since I will have do either do a custom engine swap or AWD swap no matter what car I swap the body onto? It looks like I would just be replacing one job for another, so unless that saved me from body reinforcement would there be a good reason to go that route?

@GTJIM
Thanks for the clarification and the point in the right direction.

@benncojr
A big thanks to you sir, I was going to end up trying to do this project in one setting, I will now definitely be taking your advice and breaking it up into more manageable pieces.

@RalleyBob
I have read that when doing odd ball rotary swaps, such as into Subaru RX's that vehicles with transversely mounted engines actually help facilitate the rotary swap. Would this not be true for swapping both the AWD and the rotary or am I creating a whole new type of beast? Or am I just totally mistaken?

I guess I was trying to cut corners with the AWD system, but you helped me to see that if I'm going to go this far I should be putting the top of the line AWD system in not some cheaper alternative: modern Acura or WRX AWD system it is.

@pvcar
While I'm not denying that that swap wouldn't be very nice in it's own right if I wanted to make the same amount of power out of a 1.3 liter rotary I would need to do little more than street port it. Even in stock form the engine would weigh less (180lbs stock core engine weight) and with the supercharger and related hardware the comparison would be, well, even less favorable for the supercharged in-line 4.

I'm sorry but I must admit to being a 'rotard' anyone wanting to attempt to convince me that piston engines are superior or even, I dare say, on par with rotaries has a wee bit of work cut out for themselves.

In no way do I want everyone to abandon their pistons in favor of the Wankel and any rotary owner that says they want that is either ignorant or just plain stupid. One of the many great things about being a rotary owner is the minority mentality and the fringe status that comes with our cars and engines.

@opelbits
I am familiar with Rob Millen's 4WD 1st Gen though I have yet to find any detailed specifications on his drive train.

If I was to go with a car other than the GT I would probably just go with a car that already had an AWD system in place. My interest in going with the GT is its unique look that I cannot find else where, at least not in stock form anyway.

@Travis
So would it be possible to forgo the structural reinforcement if I increased the gear ratio, or would the AWD change that? If so what would you recommend?

@everyone
Thanks again for the replies. Here are some links to some high powered rotaries if anyone that is interested:

http://cp_www.tripod.com/rotary/pg32.htm - (estimated) 700hp 13b street legal 3rd gen

http://cp_www.tripod.com/rotary/pg04.htm - stock 13b swap into an 1989 Subaru RX

http://cp_www.tripod.com/rotary/pg22.htm - Worlds fastest rotaries

Adam
 
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