spettinger

i would like to use this thread to discuss the idea of putting an engine in back.

i think this could be accomplished using a lot of stock parts, and a lot of fabrication.

my idea: stock lower control arms moved to the back, another pair of stock knuckles in back, with custom upper control arm brackets and a tie rod to hold the knuckle in place and adjust toe.
cut out the floor in back, up to the part of the unibody that the control arms bolt to. then drop the motor and transmission into the opening. put in the axles, and move the motor around until a good balance of ground clearance and axle straighteness found. then begin welding in brackets to hold the motor. radius arms would be fabricated so that the knuckle would not be able to flop excessively front to back.

shift linkage: picture the bottom of a shifter, with 4 cables attached to the bottom. 2 would be pointed side to side, and 2 going front to back. the side to side cables would twist the shift rod that goes into the transmission, and the front to back cables would pull the rod in or out. because there is a lot of versatility with mounting cables, i would want to place the shifter up high, in front of the middle air vent, closer to the steering wheel.

coolant lines: metal hardlines could be routed under the car where the exhaust tunnel is, up to the radiator in the stock location. an inline water pump would be able to help the stock pump keep the water pressure up.

heater core lines: similar routing. or bypass the heater core if you don't need heat.

wire harness: the harness would need to be lengthened by the mpfi box and the fuse box. the engine harness would stay on the motor, and the round white plug by the mpfi plug would be extended about 15 feet. on the fuse box side, i think the harness could be pulled back into the interior by the ecu, and extended about 10 feet.

fuel tank: the stock fuel tank looks like it will fit in the engine bay, mounted low to the ground. i would use the stock filler neck and leave it connected to the tank. the wire harness would need to be extended for the fuel pump and level sender. the fuel filter could stay in the same spot, and new lines would be run for the feed and the return off of the fuel pressure regulator.

battery: stock location would work, ideally, the battery would be lowered further in the engine bay to help with keeping a low center of gravity. the power wire to the starter would need to be extended to the back.

brake lines: stock front lines should work, if they don't because of length, custom braided lines will only cost about $100.

i think additional front bracing would be a good idea, without a motor in front, there is little to protect you from an oncoming crash. a decent roll cage would be in order as well.

exhaust: it would make sense to use a header that collected to one side, and run a big muffler to quiet the monster down. there should be a good deal of room to work with once the fuel tank area is removed.

i need to learn how to work my scanner, as i have diagrams on how i would lay out the shift cables and hoses.

opinions welcomed, i would like to hear some suggestions from others who have considered this possibility. thanks.


[Modified by 2ndhandCRX, 3:12 AM 1/27/2003]

spettinger

some disadvantages: no ebrake cables, possibility of poor balancing, exhaust might be uncomfortably loud. i can live with no ebrake cables, i do now anyway. the balancing could be adjusted with different springs. i think the front springs and shocks would line up in back with the front control arms.

turbohf

i see lots of thought into this, not some stupid newbie question. i have accually put lots of thought into this too. i have came up with the same basic idea as you. BUT i wouldnt try this as a street car (yours kinda sounds like that). you would need to make a firewall and **** too...

what engine/tranny setup are you thinking about?


[Modified by turbohf, 12:31 AM 1/27/2003]

uneek4dr

already been done more than once.
A shop in atlanta where i used to live did a CR-NSX
An acura NSX mounted in the rear. if you want pics ill try to find links. it was at nopi

spettinger

i have a b16 in the car now, and i have bought an ls block from a junkyard. i would do an ls vtec with b16 pistons. i have some other parts sitting around, i might get some crower2s for pretty cheap from a friend. a firewall would be put in once the motor was in the right spot and running well. i think i would weld tabs inside for the firewall to bolt to.

forgot one very important thing: earplugs.

spettinger

any and all pics are welcomed!! did they use custom trailing arms or relocated stock knuckles?

pfcfutrell

The shop is called Mahdavi Motorsports, i believe their website is mahdavimotorsports.com. I saw it at Hot Import Nights in Atlanta, pretty sick but it is a race car not a daily driver by any means.

tylerdurden

It is definitely not for a daily driver, but don't let that stop you. The only possible problem I see is the cooling system. I don't know how much I trust 10 feet of coolant lines (it might not be a problem, just seems like a vulnerability). I would also be kind of leery of the custom fabbed suspension pieces. Suspension geometry is a complicated thing. The balance of the car overall could pretty easily be adjusted with custom rate coilovers. You could pretty easily fabricate a stainless steel firewall with some insulation to quiet it down and keep heat out. Someone did just this with the ford focus (I believe the company is called Phase-X or something like that. try focaljet.com) and it seems to have worked out very well for them. Maybe give them a call and see what they can tell you. I for one would be very interested in a rear mounted b20. Keep us updated.

spettinger

as for the coolant lines, the MR2 has a front mounted radiator. i would definitely trust metal lines under the car in the exhaust tunnel. the unibody would bottom out before the lines would hit. i do agree that suspension geometry is complex, but it is not supposed to be intimidating. i am currently reading Chassis Engineering by Herb Adams. it is a great book to introduce the novice engineer to the art. the only suspension component i would need to fabricate would be the upper control arm mounting points, and i trust my welding skills. as for the radius arms, those would be another no brainer, just some tabs to some reinforced plates under the unibody. thanks for your interest, i would love to get a donor shell to attempt this on, otherwise i need to buy another beater to cruise around in while my car goes under the knife.

spettinger

oh, and i don't see what would stop it from being a daily driver? i don't see how the reliability would be changed much, it would stay naturally aspirated so the ecu and control the car without any problems, and all of the relays will remain where they are. there are not too many wiring changes, just extensions. and because none of the sensors depend on a certain length of wire for accuracy, it makes no difference how long the harness is.

philly-O

i think that you are on to something here and that it is definately possible. instead of using the stock filler for the gas tank & relocating the stock tank just make a floor for the now open engine bay and mount a fuel cell under the hood and fill it that way. i also think by closing off the underside of the open engine bay will help aerodynamics alot as well as giving it much added strength. i am not sure of the name of the shop, but there is a streetrod builder in northern illinois that is a master in building custom rollcages if interested. plus it would be cool to see the enging through the rear hatch! i think that you can do it and wish you luck. keep me updated if you go ahead with the project

philly-O

yeah i forgot to mention that you would have to fab some type of rear frame for the crx not only for strength but to mount the motor to.

spettinger

the rear end would be as close to tube frame as unibody gets. as for aerodynamics, i would need all the help i could get to keep the front wheels on the ground under power. not to say that an ls vtev would pick the front wheels up, just that the car would squat very hard and transfer almost all the weight through the back. perhaps the fuel cell could go behind the seats in front of the fire wall, and i could run a duct from the front grill, through the radiator, and out of the hood? mugen's nsx has it, why shouldn't i?!

spettinger

i think the rollcage/ fabrication shop is off of 64 by 47, out past Elburn, by northern illinois university. i went past his place one time, and they were closed. in their front showroom was a piston and rod combo that were as big around as my leg, not to mention a bunch of tube frame hot rods being built in back! it was big block heaven! i would love to volunteer there, just to sweep the floors near those monsters.

model x

I've also been thinking about this for a little while.
I thought about removing the lower rear window and a rear side window for a radiator or intercooler setup and the intake air supply.
This is definitly a project I'd like to try in the distant future.

Do you remember the guy on HorsePower TV that had the chrysler turbo engine in the back of a first gen rex, it was the same episode they put the Xenon kit, ST lowering springs and 17s on the second gen.

uneek4dr

yeah mahdavi is the place that did the CR-NSX
I'm not sure if they ran it at the track yet or not. Try the site http://www.mahdavimotorsports.com

shortyz

u could hook the shifter up stock location except everything would be switched upside down.

1st to second would be UP instead of down
ahha

ThatRicerDaniel

theres also that turbo h22 from hawwaii .. some one here showed me . or for fun you could mount the motor in the rear backwards and have the fastest honda in reverse .. make all the mags .. hahaha ..


[Modified by NitrousDreamz, 2:31 AM 1/27/2003]

Wes V

You may want to do a web search on "Porsche V8" and read through conversions to Porsche 911 and 914's to Chevy V8 power. That could answer a lot of questions.

As for water pump, I'd think about using one of the Maesire (spelled wrong) electrical ones as a supplement to the engines pump.

It shouldn't be all that difficult. Think about this; when G.M. made up the Fiero, all they did was take a complete Citation front engine, transmission, and suspension package and put in in the rear. (that's part of the reason that the early ones didn't handle well) They just used a linkage arm attached to the spindles to prevent the rear from "steering".

I think that if I was to do it, I'd try designing the suspension after one of the Toyota MR2's. A little known fact is that the original design of the MR2 was done by Lotus and they were going to produce it. They lost interest and sold the design to Toyota. Heck, I wonder if it would be possible to get custom axles made up to use the MR2's spindle and hub?!?!

Wes.

spettinger

some of you guys haven't realized that a solid shift linkage would be next to impossible. normally, with the engine in front, the shift linkage would run directly to it. in this situation, the transmission will be behind the shifter, so the linkage would need to run underneath the trans to some sort of leverage arm that could twist and pull the transmission shaft into the proper gear. my idea is to run cables that would pull side to side and front to back to imitate the solid shift linkage. i would try this on my car with the current B16 setup in the traditional location, and move the shifter up next to the wheel, where most rally cars have their sequential shifter.

shortyz

lol forgot about that!
hahah

ComposiMo

If you want the answer to most any question you have about this conversion, there is a resource available to you... i've thought looooooooong and hard about this swap, and done a ton of drawings, brainstorming, etc.... basically everything but actually doing the car...

Have a look at the Spec Racer Ford SCCA cars. They use(d) a Renault/Ford engine setup that is from a front wheel drive car, and is configured MUCH the same way as our honda engine/tranny. The shifter input comes out of the back, and operates almost identically, and the suspension arms/hubs are fairly close as well. The shifter used on the spec racer car is really quite ingenious, and it is solid (no dinky cables to worry about). Baically, it goes straight back under the tranny, and there is nothing more than a short rod that goes straight up, and connects to the shifter input. When you push the shifter to the right, it still twists the shifter input in the proper direction, and when you move the shifter forwards and backwards, it sstill moves it in those directions as well.... basically, it still shifts the car like stock. The only thing about it, is because it essentially moves the fulcrum point (because of the extension), you have to use a long-throw shifter so that you can still have a usable short-shifter... if you use a short shifter, it would wind up too short, and hard to shift.

Anyway, just a thought for you guys... i know that this would be an awesome swap to do, and i'd love to do it... but time/money say that i have other things i need to do before tackling this one... heh. By the way, once you see the setup in a Spec Racer Ford car, you'll practically slap yourself in the head when you realize how simple everything really is. The hardest part about all of it, is mountingthe front suspension in the rear... But of course i guess if someone was inventive/creative enough, they could figure out a way to use the rear trailing arm from a CRV Then all you'd have to do is get a custom axle, and mount the engine in the car.

speedy-crx

yea i posted pics of the cr-nsx on here befor but everyone hated it and said it was a waste of money and that sam mahdavi was crazy but i think it was one of the coolest things i have ever seen they ran it at commerce last year it ran 11.3ish on its first run with zero tuning and that was the only run they got a good time the other times it got fuel cut off or something and only ran 12ish but you have to remember that they built that whole car for less than 10k and it ran that with zero mods just imagine with basic bolt ons or something major like turbo it would be unstopable

Crxer

If you're going to put the engine in the back, you might as well spend some extra time on making it RWD

Harrytallywacker

I disagree with your proposal, if I had it my way, I would take the shaft and rub it against my rod...........but the only problem is that there may be some valve lash, from stroking it too hard.