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AMC Spirit Rally Car

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73Gremlin401 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/06/2017 at 8:47pm
i think it's pretty nifty to build a Spirit rally car - the sedan/ex Gremlin shell is a bit more rigid than the SX/4 Spirit/AMX shell, and weighs a bit less too.

i agree with some of the other posts about going with the IronDuke, even though your particular car has the Audi motor, as the GM motor does have some longevity under abuse characteristics that the 2.0 doesn't have.

That said, the Audi motor weighs less, and potentially could wind a bit tighter, with a wider powerband, which as you posted is a necessity for rally use.  and your car is set up for it with the proper crossmember, etc.

back in the day, before AMC pulled the plug on motorsports, Team Highball was experimenting with the 2.0 motor for their Gremlins and Spirits, which i did get to drive some when i was down there, and they were every bit as strong power wise as the 3.8 6 cyls they were running at the time. granted, part of that was the weight advantage of the Audi motor.  The big deal was the improvement in handling balance - it totally transformed the car.

As for being allowed to run the GM motor in rallys, it is a bit weird in this particular instance since your specific year model shell didnt come with it.  on the other hand, who's really going to care.  Rally America probably won't, NASA Rallysport for sure wont, and ARA might not.  so build what you want and have fun.  I'm happy to contact my folks at any of them for you.

on the suspension thing, Nickleone knows what hes talking about.  the big wear advantage you'll have running the 2.0 is you wont have a 700# lump of iron crashing down of the front suspension over every crest.  While i do very much like the Control Freak setup, i dont think that they have engineered it for the kind of suspension travel you need from a droop standpoint.  Id definitely call Al down there and ask.  Also, I don't know if they've ever adapted their setup  to either of the 4cyl motors. On my Gremlin, which is a combo road/tarmac rally/hillclimb car, i'm running boxed stock control arms like Nick, urethane bushings in most locations, and inverted coil-over dampers with adjustable ride height spring perches up front, and stock leafs in the rear with nylon bushings and coil-over adjustable dampers. its not high tech, but it works.

Good luck!  very glad to see an AMC back in any form of rally.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 9:52am
The higher revving potential of the four isn't really a plus. With the six, you have more low speed grunt (torque) than the four -- NO NEED TO WIND IT UP! One of the guys in Atlanta was having a bit of trouble being competitive with his 258 powered Spirit in SCCA class racing. He had driven an little Austin-Healey Sprite before building the Spirit and was used to winding the engine up. Solution was simple -- don't wind the engine so much, and go with a five speed and lower rear axle -- use the engine's inherent torque  to pull out of the curves. A change in driving style (from high revving to using grunt) pushed him from the last 25% of the pack to the first 25%, even got a couple class wins. Before the higher revving cars were pulling away in curves -- all due to driving style! After some "retraining" he was pulling out of the curves quicker. While the higher revving cars were catching up on the straights, he was still out pulling them from the curves.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 12:11pm
Originally posted by farna farna wrote:

The higher revving potential of the four isn't really a plus. With the six, you have more low speed grunt (torque) than the four -- NO NEED TO WIND IT UP! One of the guys in Atlanta was having a bit of trouble being competitive with his 258 powered Spirit in SCCA class racing. He had driven an little Austin-Healey Sprite before building the Spirit and was used to winding the engine up. Solution was simple -- don't wind the engine so much, and go with a five speed and lower rear axle -- use the engine's inherent torque  to pull out of the curves. A change in driving style (from high revving to using grunt) pushed him from the last 25% of the pack to the first 25%, even got a couple class wins. Before the higher revving cars were pulling away in curves -- all due to driving style! After some "retraining" he was pulling out of the curves quicker. While the higher revving cars were catching up on the straights, he was still out pulling them from the curves.


yes.....but.  Rally is a much different motor situation than road or oval racing. i absolutely agree, especially with all the time i have in both my 6 and v8 Gremlins at road racing venues, that i rarely had a need to zing the motors over 5k, as i could just use the grunt down low.

in rally, which is done 95% of the time on low traction surfaces, with constant small and large elevation changes, powerband flexibility and range are everything.

BTW, I remember that guy at RdAtl, you and i both talked with him....1996 or so i believe?


Edited by 73Gremlin401 - Oct/07/2017 at 12:14pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aljav Quote  Post ReplyReply Direct Link To This Post Posted: Oct/07/2017 at 10:05pm
Why not use a jeep 2.5? Good HP and Torque. and fuel injected. Just a thought.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2017 at 9:59am
Originally posted by Aljav Aljav wrote:

Why not use a jeep 2.5? Good HP and Torque. and fuel injected. Just a thought.


Stout, reliable, torquey motor for sure but zero RPM potential with very narrow power band.  well suited as a mild jeep motor, not the ticket for rallying.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2017 at 10:08am
That's why the five speed with the AMC six -- keep it geared down. A six speed would even be better, but then you're talking a lot more money even if the rules allowed it. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2017 at 10:30am
Originally posted by farna farna wrote:

That's why the five speed with the AMC six -- keep it geared down. A six speed would even be better, but then you're talking a lot more money even if the rules allowed it. 


SFAIK, transmission choice is quite open in most rally classes, so that's not a problem.  the problem with more gears, is that a rally driver has better things to do with his right arm than be constantly swapping gears trying to keep the motor on full boil.  wide powerband and large RPM flexibility is everything in rally.  very different than in most any tarmac based motorsport other than perhaps autocross.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2017 at 10:58am
Originally posted by 73Gremlin401 73Gremlin401 wrote:


Originally posted by farna farna wrote:

That's why the five speed with the AMC six -- keep it geared down. A six speed would even be better, but then you're talking a lot more money even if the rules allowed it. 



SFAIK, transmission choice is quite open in most rally classes, so that's not a problem.  the problem with more gears, is that a rally driver has better things to do with his right arm than be constantly swapping gears trying to keep the motor on full boil.  wide powerband and large RPM flexibility is everything in rally.  very different than in most any tarmac based motorsport other than perhaps autocross.


That is what was thinking, almost keeping the engine at top RPM range all the time. I think the turbo 4 will do better for weight and balance even if it may not have the torque the 6 cyl has. Having the proper gears setup should make such comparison a wash once the turbo kicks in.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 73Gremlin401 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/08/2017 at 1:48pm
Originally posted by 304-dude 304-dude wrote:

Originally posted by 73Gremlin401 73Gremlin401 wrote:


Originally posted by farna farna wrote:

That's why the five speed with the AMC six -- keep it geared down. A six speed would even be better, but then you're talking a lot more money even if the rules allowed it. 



SFAIK, transmission choice is quite open in most rally classes, so that's not a problem.  the problem with more gears, is that a rally driver has better things to do with his right arm than be constantly swapping gears trying to keep the motor on full boil.  wide powerband and large RPM flexibility is everything in rally.  very different than in most any tarmac based motorsport other than perhaps autocross.


That is what was thinking, almost keeping the engine at top RPM range all the time. I think the turbo 4 will do better for weight and balance even if it may not have the torque the 6 cyl has. Having the proper gears setup should make such comparison a wash once the turbo kicks in.



This.  the downside is that if i read the OPs post correctly, he's looking at running in the small bore 2WD class, which here in the states generally does not allow forced induction, but does allow a fairly wide range of engine/transmission modifications, short of a dog box, depending on the sanctioning body.

my memories of driving the Highball 2.0 Spirit, while many moons ago, were that the motor's potential was there, but the real benefit was the massive improvement in front/rear weight balance on that short 96" wheelbase.

My gut feeling is that the OP could have a fun, mid-pack Rallycross and stage rally car with relatively little development of the 2.0, and something that could give the front of pack cars a few raised eyebrows with a bit more development of suspension and drivetrain.  I'd love to see it happen.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jebidia24 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/30/2017 at 1:56pm
It took awhile but I got some quick pics of the engine out of the car with most of it's accessories removed. I am a little concerned over the natural angle the engine sits in the spirit vs the 924 in terms of intake manifold and exhaust, they may need to be modified.
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