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Old 07-30-2009, 08:04 PM   #1
SoFresh1189
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RWD civic with rotary motor

Whats up everyone, im brainstorming a project right now and im looking for some insight/advice. Ive got a spare 97 Honda Civic Dx coupe in my backyard with no motor and im completely stripping it out to build up something monstrous . i started out researching fwd motors to build up considering it would be a somewhat easy swap because a lot of honda motors will drop right in with little modifications. During my 4bangin' studies a buddy of mine, who is into the older muscle cars, said i should just get a 350 v8 for it and he would help me put it all in. So i started researching that. ive found that a f$&@load of custom fabricating is required including frame rails, differential installation and so forth. Now, considering im only 19 i was born and raised in the tuner era (i shouldnt say raised because my parents were not mechanics but w/e i do my research) so i dont know the first thing about a v8. Still exploring my options, i started to look into rotary motors because ive always admired the rx7. i found theyre much lighter than a v8 and can produce similar power with little modification to the motor, on the downside tho they dont usually last more than 100k miles but who cares its a race car not a daily driver. Shit, if you do the math thats roughly 400,000 quarter mile runs, which is plenty. To get to the point im not afraid of the time, work, and money this will cost but just for arguements sake lets assume the money part isnt an issue. My question(s): to drop a rotary motor into my civic shell would i need to do something with the firewall? and if so how would i go about keeping the heat away from the driver? As far as the rwd conversion, is the differential different for every motor or could i hook up any drivetrain/differential to any rotary motor + transmission? Ive also read the gas tank may have to be relocated, where to? Or, if possible would it be easier to drop the shell onto the whole chassis setup off an rx7? I know i still have to buy an rx7 im looking into getting a salvaged one

Ive only seen pictures of 1 person who put a rotary in a civic and i think its a great idea, considering that a honda shell with an rx7 motor would weigh almost 200lbs less than an rx7 with an rx7 motor, and also the civic has a wider wheelbase which if im correct would handle better (especially lowered)

What do you think?
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Old 07-30-2009, 11:43 PM   #2
fudge
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It would be easier dropping the Civic shell onto an RX7 chassis but given the choice I would drive the RX7 and do something else to the civic. There was a writeup on a Honda forum which someone dropped a Civic shell onto a Corvette chassis which was cool.

And if you managed to put a rotary in the Civic it wouldn't necessarily out-handle an RX7 - it all depends on the tuner as the balance and suspension geometry of the car might have been compromised in the build. If you do it right then yeah but in a one off DIY project that is not likely to happen straight away - there will be allot of little problems you'll encounter. Heck I'm having problems building up my Megasquirt system

Get your research in with the parts you'll be hoping to use. And you can use any differential/transmission with the rotary as long as you can fabricate it to make it fit(Bellhousing, propshaft etc). I think you're biting off more than you can chew - cars like this can takes pro's many months to build. I recently visited a local Motorsport engineering place where they were building a K20A powered AWD Mini which suits the super 2000 specs It takes shit loads of work and effort even for those guys with years of experience as well as modern machining equipment(3 axis CNC machine in workshop!).
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Old 08-02-2009, 04:59 PM   #3
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Honestly...I think you're dreaming. However I'd like nothing more than for you to prove me wrong.

Past that, don't be so quick to think the Wankel rotaries are super-lightweight. With all the turbo and manifold stuff the engine weighs about as much as an LS1 (Alumunim block 5.7 liter V8 GM produced from about 1997-2004). So much so that is is very common to see people swap out the 1.3 rotaries for the LSX motors. My understanding is that the 13BT with tranny is about as heavy as an LS1 with tranny, and the 20B is heavier than that. Now factor in the reliability issue, the cost of modding issue (LS1s are easy and relatively cheap to mod) AND the fact that the RX7s with this big 5.7 liter engine handle better due to the flat torque curve of the V8, and well, the rotary engine is cool, but not always they best choice for performance. Not to mention a rotary has what, 250hp and probably very little torque while an LS1 has 350hp and 350+ ft-lbs of torque stock.

Next: A motor that tends to last 100,000 miles does not = 400,000 dragstrip passes. The stresses a dragstrip puts on the motor/drivetrain is incomparable to 100,000 street miles. If this is going to be a dragracer be prepared to do some rebuilds.

Yes, I'd say it's going to be a hell of a lot easier to but a Civic body onto an RX7 frame. Compared to making a Civic a RWD car that needs to handle a good deal of power, dropping a rotary or 350 into a Civic is childs play. There is a reason you see very few RWD swaps; it is a shitload of work and if not done properly it's going to get ugly at the dragstrip.

You're planning on doing a RWD swap on a Civic and your primary concern is about not knowing what to do with the firewall? You're in over your head. What work have you done on cars in the past?
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Last edited by giant016 : 08-02-2009 at 05:02 PM.
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Old 08-03-2009, 04:40 PM   #4
SoFresh1189
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actually i havent done a whole lot of work on cars im no pro but ive got a pretty good idea what im doing. the rwd conversion is a definite i bought the rear subframe from an s2000, which i presume will answer my gas tank question. and the whole rear suspension will probably be from an s2000 as well. now, im not expecting this to plug and play in the least but i know my way around a welder and i know enough people with the proper equipment and professional know-how that i need. the rwd conversion has been done before so ill have somewhere to reference that from to get it right. the only thing im debating now is which motor to put in it. ive done extensive research on rotary motors but not nearly enough but ive got until i finish the rwd conversion to figure that out. as for the firewall issue that will probably all have to be figured out after i decide what motor to drop in it
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Old 12-13-2009, 12:06 AM   #5
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Quote:
Originally Posted by SoFresh1189
actually i havent done a whole lot of work on cars im no pro but ive got a pretty good idea what im doing. the rwd conversion is a definite i bought the rear subframe from an s2000, which i presume will answer my gas tank question. and the whole rear suspension will probably be from an s2000 as well. now, im not expecting this to plug and play in the least but i know my way around a welder and i know enough people with the proper equipment and professional know-how that i need. the rwd conversion has been done before so ill have somewhere to reference that from to get it right. the only thing im debating now is which motor to put in it. ive done extensive research on rotary motors but not nearly enough but ive got until i finish the rwd conversion to figure that out. as for the firewall issue that will probably all have to be figured out after i decide what motor to drop in it

Period.
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