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Lightweight engine for a 620


makya

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12 hours ago, Stoffregen Motorsports said:

Why only 35's? Cut the fenders and lower the shit out of it and still run 37's or even 40's. Lots of trail rigs are running 40's with 2-3 inches of up-travel these days.

 

I don't remember what the frame profile looks like on a 620, but you could always cut the frame off around the VIN and raise it. Move the motor back and push the axle forward so the crank pulley is behind the axle centerline. For gearing, use a 280ZX turbo T5 bellhousing, a Jeep T5 trans and a Dana 300 with 4:1 gears. I've never built this combo, but I have done the research and it seems like it should work. 

 

This guy sells adapter plates for KA24 to GM "manual/auto trans" - https://www.bobsautomotivemachine.com/products/

 

I don't think I have ever seen a 620 built into a serious trail rig, but I can picture it in my head.

I want to drive it on the road, and keep weight down. I have the "original" dealer converted '75 620 and think I'm just going to change out the shafts to the 297 ujoint shafts and 44 outers also, which also would limit me to 35s.

 

Part of the idea for an oddball motor like the boxer, is that its shorter in length and height, which would give me more room to drop the chassis lower over the axle.  The part I hadn't thought of until I started typing this out, is that it's a wide motor that could end up interfering with suspension links, being low. I need to measure this weekend and draw some of it out 

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12 hours ago, Lockleaf said:

Really it sounds like you are looking for entertainment as the primary goal, with the weight/power of the engine as secondary.  In that case, I ask what do you want to put in it?  What seems like a lot of fun to mess with?

 

TDI w/ Toyota Trans is small with good power that can be made.

Cummins makes 4 cylinder diesel crate motors just for powering small offroaders.

VQ35w/ obd1 vq30 engine controls

VH45 to D21 transmission

4 cylinder turbo Sky/Soltice motor w/ Colorado trans/tcase

 

Or really go down the rabbit hole.  "Home Built by Jeff" on youtube is building a 60s alfa romeo with  ferrari Modena V8 connected to a BRZ 6 Speed for front engine/ rear wheel drive fun.

I really want to build light, so a diesel is out, I also got a look at the 2.8d crate motor for the jeep, and its too tall.  I do like the aluminum Nissan/ infiniti motors, I'm not familiar with the turbo gm motor, ill look into it, thanks.

 

   

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11 hours ago, makya said:

I want to drive it on the road, and keep weight down. I have the "original" dealer converted '75 620 and think I'm just going to change out the shafts to the 297 ujoint shafts and 44 outers also, which also would limit me to 35s.

 

Part of the idea for an oddball motor like the boxer, is that its shorter in length and height, which would give me more room to drop the chassis lower over the axle.  The part I hadn't thought of until I started typing this out, is that it's a wide motor that could end up interfering with suspension links, being low. I need to measure this weekend and draw some of it out 

Another problem with a boxer is the exhaust. It would dump right onto the front driveshaft.

 

How big are the axle tubes on those dealer installed D30 axles? 2.5" probably, which is another weak link. And trussing one just takes up so much valuable space.

 

The Ford ecoboost 4cyl makes 250hp stock and is sold as a crate motor for about $6500.

 

You could really think outside the box and make it a mid engine rig.

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8 hours ago, Stoffregen Motorsports said:

Another problem with a boxer is the exhaust. It would dump right onto the front driveshaft.

 

How big are the axle tubes on those dealer installed D30 axles? 2.5" probably, which is another weak link. And trussing one just takes up so much valuable space.

 

The Ford ecoboost 4cyl makes 250hp stock and is sold as a crate motor for about $6500.

 

You could really think outside the box and make it a mid engine rig.

Good points. The boxer is probably out in that case. 

I'm not really worried about the axle, im going to be running at places like Mojave rd, not the rubicon.  I have an 81 toyota for rock crawling.

I did look up the ford 4 cylinder aluminum block already as a build option. Spec'ing it out, it could be built up as a nice engine for what I want, and I do have an m5od (don't really want to use that horrible slave cylinder though)

The dodge srt4 motor was also an option.

 

I dont want to go mid engine, i'm still planning on carrying gear with me.

 

I was planning on heading out tomorrow to go take some measurements and get some ideas after I finish up the heater core on my amigo.

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  • 1 month later...

A guy I know is building a 3/4 scale crawler from scratch. It looks like a mini flat fender Jeep and is going to be powered by a 1.0L Geo 3 cylinder. - https://www.instagram.com/brennanmetcalf/?hl=en

 

Another good friend of mine has a completely custom Geo Tracker with the stock engine, custom chassis, link suspension, custom axles and 37" sticky tires. I have driven that rig and power is just not an issue. Because it revs! -

 

Edited by Stoffregen Motorsports
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