Cosmo 20B Swap
11-29-10, 10:14 PM
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Cosmo 20B Swap
Alright so I own a 91 Rx7 Vert N/A and was considering doing the Cosmo 20B swap. I was wondering if anyone out there has done it and has some tips for what I want to do. I know everyone will say is really expensive but I found a JDM site that has the whole front clip for 4 grand.
One question I have is what motor mounts do you use?
Is there any custom fab I would need to do?
How hard is it to do?
Please send any info or sites that could help Thanks
One question I have is what motor mounts do you use?
Is there any custom fab I would need to do?
How hard is it to do?
Please send any info or sites that could help Thanks
11-29-10, 11:21 PM
#3
11-30-10, 09:11 PM
#5
search search search. You could read for days straight on that subject... Plan on at least $8000 to complete the swap though. You mentioned a JC cosmo front clip, keep in mind(as far as I know) no one has swapped them and ran them on the full JC cosmo electronics.
If your serious about it, you could make it work, but it'll take a lot of dedication.
If your serious about it, you could make it work, but it'll take a lot of dedication.
11-30-10, 10:36 PM
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same with mine lol
hope your pockets are deep OP... just sayin.
hell bent on a 20b swap... read this.
http://fc3spro.com/TECH/SWAP/COSMO/20b.html
hope your pockets are deep OP... just sayin.
hell bent on a 20b swap... read this.
http://fc3spro.com/TECH/SWAP/COSMO/20b.html
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12-07-10, 12:01 PM
#8
As the rotary elders have mentioned, you need to start with the Second Generation FAQ, conveniently stickied in the Second Generation section. After that, read up in the 20b section to get your feet wet. Attila the Fun's RXX-7 build is a good place to start with. And once you're confused by all the options and numbers being thrown out there, look at my thread "The 12 Days of Rotormas" in the second gen section.
I'm currently in the process of doing a 20B-REW conversion in my 87 GXL. Car was originally an automatic, converted to manual trans 6 months after I bought it in late 07. Engine is a Pre-A code, #352 originally built on Friday, April 13, 1990. Yup, Friday the 13th!
The 20B engine mounts are my own design, based loosely on the FC's stock engine mount brackets and with a little inspiration from Banzai's mounts, but made MUCH stronger thanks to being constructed from 1/4" flat iron and having a reinforcement rib between the stud side and bushing side so they can't bend out of shape from compression.
They were welded together by a race engineer/aircraft engineer buddy that's been into rotaries since the 1970s. He said the strengthening rib wasn't necessary, thanks to how strong the material and welds he put on them are, but I insisted in order to make them so beefy that they'd be scraping me off the pavement before they broke or bent out of shape. To illustrate it, he told me to stomp on one as hard as I could. I'm not a big guy (5'10, 165lbs), but I did so hard enough to leave a nasty bruise and the mounts didn't budge. I'm not knocking Banzai's mounts, but I just felt that the $210 pricetag seemed a bit steep for what is essentially bent 1/8" sheet metal with a couple tig welds on each piece.
Most guys use a TII hood, but I'm insisting on keeping the N/A Hood by cutting out a couple braces so it'll clear the UIM. The TII hood does require modding a couple of the braces though. Another option to clear the hood is to shorten the LIM as Defined Autoworks does with their 20B FCs and FDs. Christopher W's 1989 GTUs is getting that treatment right now.
Electronics are gonna give you the most nightmares if you try to re-use the Cosmo's NF01 ECU. Search and you'll see why. Most guys lean towards the Haltech E11v2 or Platinum Sport 2000 due to the ease of install, support and wide breadth of extra functions they can do. Plus, a standalone means having a fresh, unbaked harness in perfect condition. That in itself makes it worth the investment. I'm using the PS2K in my car.
All engine accessories are bolt-on, just re-use your s5 brackets. You'll have a little trouble getting the P/S pump on, but I assure you that it will go on by undoing one of the hose P-clamps. A/C is another story that I've yet to tackle though (hose from firewall is too short, condenser needs relocated, etc). Anyway, read up on my thread and you'll get a firsthand account of the challenges I'm facing with a first-time engine swap and how someone with little experience but a clever imagination can overcome these issues by being creative and re-using the stock parts in new and sometimes brilliant ways. And for the other stuff, I highly recommend reading Aaron Cake's build threads too.
Good luck and remember this tidbit: If it weren't for people dreaming up cool ideas and doing stuff 'that can't be done', the rotary community would have never come to be. As Felix Wankel said "Imagination costs nothing. We could build square locomotives or fly to the moon.".
I'm currently in the process of doing a 20B-REW conversion in my 87 GXL. Car was originally an automatic, converted to manual trans 6 months after I bought it in late 07. Engine is a Pre-A code, #352 originally built on Friday, April 13, 1990. Yup, Friday the 13th!
The 20B engine mounts are my own design, based loosely on the FC's stock engine mount brackets and with a little inspiration from Banzai's mounts, but made MUCH stronger thanks to being constructed from 1/4" flat iron and having a reinforcement rib between the stud side and bushing side so they can't bend out of shape from compression.
They were welded together by a race engineer/aircraft engineer buddy that's been into rotaries since the 1970s. He said the strengthening rib wasn't necessary, thanks to how strong the material and welds he put on them are, but I insisted in order to make them so beefy that they'd be scraping me off the pavement before they broke or bent out of shape. To illustrate it, he told me to stomp on one as hard as I could. I'm not a big guy (5'10, 165lbs), but I did so hard enough to leave a nasty bruise and the mounts didn't budge. I'm not knocking Banzai's mounts, but I just felt that the $210 pricetag seemed a bit steep for what is essentially bent 1/8" sheet metal with a couple tig welds on each piece.
Most guys use a TII hood, but I'm insisting on keeping the N/A Hood by cutting out a couple braces so it'll clear the UIM. The TII hood does require modding a couple of the braces though. Another option to clear the hood is to shorten the LIM as Defined Autoworks does with their 20B FCs and FDs. Christopher W's 1989 GTUs is getting that treatment right now.
Electronics are gonna give you the most nightmares if you try to re-use the Cosmo's NF01 ECU. Search and you'll see why. Most guys lean towards the Haltech E11v2 or Platinum Sport 2000 due to the ease of install, support and wide breadth of extra functions they can do. Plus, a standalone means having a fresh, unbaked harness in perfect condition. That in itself makes it worth the investment. I'm using the PS2K in my car.
All engine accessories are bolt-on, just re-use your s5 brackets. You'll have a little trouble getting the P/S pump on, but I assure you that it will go on by undoing one of the hose P-clamps. A/C is another story that I've yet to tackle though (hose from firewall is too short, condenser needs relocated, etc). Anyway, read up on my thread and you'll get a firsthand account of the challenges I'm facing with a first-time engine swap and how someone with little experience but a clever imagination can overcome these issues by being creative and re-using the stock parts in new and sometimes brilliant ways. And for the other stuff, I highly recommend reading Aaron Cake's build threads too.
Good luck and remember this tidbit: If it weren't for people dreaming up cool ideas and doing stuff 'that can't be done', the rotary community would have never come to be. As Felix Wankel said "Imagination costs nothing. We could build square locomotives or fly to the moon.".
12-07-10, 06:54 PM
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building the dash harness, even with the wiring diagrams is actually a pretty big task, and then the ECU is still tuned for a bone stock engine, oh and its also looking for a TON of parts, like solenoids, and sensors and it gets an ignition feedback signal, etc etc etc etc etc
the standalone is in this case, much easier.
12-12-10, 07:17 PM
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12-12-10, 07:20 PM
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Did I mention that mine is for sale? $19,900--much less than the cost of doing the conversion.
12-13-10, 05:39 PM
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No, it's only about $5,000 to get a 20B in an FC if you do the work yourself. It's another $5,000 or so to make it run properly. At that point you are finished if you are happy with a basically stock RX-7 with an overpriced yet neat-looking 300hp engine. Most people who go through the trouble of a 20B swap will want to add a lot of go-fast goodies, which will obviously add a lot more time and money. A typical professional 20B conversion will run about $35,000, as explained earlier. The RXX-7 car linked in this thread has additional mods, such as a body kit, custom roll bar, etched glass, powder-coated parts, etc., which will of course add to the cost. The car is definitely fast, and by that I mean well-balanced and well-engineered by a race shop as opposed to simply being overpowered because some noob wedged a bigger engine under the hood of his rust bucket.
https://www.rx7club.com/forum/showthread.php?t=886208
https://www.rx7club.com/forum/showthread.php?t=886208
12-14-10, 12:41 PM
#20
No, it's only about $5,000 to get a 20B in an FC if you do the work yourself. It's another $5,000 or so to make it run properly. At that point you are finished if you are happy with a basically stock RX-7 with an overpriced yet neat-looking 300hp engine. Most people who go through the trouble of a 20B swap will want to add a lot of go-fast goodies, which will obviously add a lot more time and money. A typical professional 20B conversion will run about $35,000, as explained earlier. The RXX-7 car linked in this thread has additional mods, such as a body kit, custom roll bar, etched glass, powder-coated parts, etc., which will of course add to the cost. The car is definitely fast, and by that I mean well-balanced and well-engineered by a race shop as opposed to simply being overpowered because some noob wedged a bigger engine under the hood of his rust bucket.
https://www.rx7club.com/forum/showthread.php?t=886208
https://www.rx7club.com/forum/showthread.php?t=886208
I like my rusty FC and the uber-cheap 20b build, using proven recycled parts found on the cheap. Sure, a single turbo 20b has more top end power, but you have to wait till 3000 or so rpm to see any boost. And then there's the cost of going single turbo too. Or if you go N/A, you'll still be spending $1700 on a properly made exhaust manifold such as the one from Defined Autoworks. Nothing against them, as their fab work is top notch. In my mind, putting that coin towards a Haltech just makes more sense.
My car uses very few custom fabricated parts and will spool at idle once the IC plumbing is finished. Every piece I've had to make is durable, definitely no-frills and is simple to understand and build. Plus, it's a 300hp stock FC that has 300ft.lbs of torque starting at idle. Once I get it finished, dyno graphs will be posted for all to see. Besides, innovation comes from not having the 'right' parts to work with.
12-14-10, 12:46 PM
#21
20B is more for those with a full shop at their disposal. when i get this one going it's going to start out n/a HBP. $1700 for a manifold? you know you can buy a used tig welder and the materials for that price right? but they apparently price it for those who can't be bothered and have extremely fat wallets to do the swap anyways and mainly why so many of these builds do wind up costing $20-35k+, because those people are being taken advantage of.
Last edited by RotaryEvolution; 12-14-10 at 12:48 PM.
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