ghetto 4 rotor build
Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
ghetto 4 rotor build
That's right. Doing a 4 rotor on the cheap.
It's going into a GSL-SE. The car will be CYM (competition yellow mica; 3rd gen color) so we already painted the engine bay. The rest of the car will be done after the engine is installed.
The stripping of the old engine and painting the bay was the first step. The second was to put together a mock up engine. Third to test fit it. Fourth build motor mounts. Fifth... well, I'll let this first group of pictures speak for themselves.
It's going into a GSL-SE. The car will be CYM (competition yellow mica; 3rd gen color) so we already painted the engine bay. The rest of the car will be done after the engine is installed.
The stripping of the old engine and painting the bay was the first step. The second was to put together a mock up engine. Third to test fit it. Fourth build motor mounts. Fifth... well, I'll let this first group of pictures speak for themselves.
Jeff, you've been on a roll lately, i know know you've been making me think much harder of enginge builds, combinations of parts and porting/air flow dynamics. This is by far the wildest one yet. Very interested in how you plan on constructing the e-shaft. That should be an adventure initself.
Are you going to need to cut into the firewall or install the rad at slat or even flat to get the clearence needed?
Are you going to need to cut into the firewall or install the rad at slat or even flat to get the clearence needed?
Yah right...
4 rotor 12a.... this is the one we all dream about....
Now thats a project...
What intermediate plates are those?
What are you gonna do about stat. gears for the middle rotors?
heck... are you using tension bolts from either end of the block, or are those just mammoth???????? Going for any bracing on that big daddy, I forsee a bit of torsion there!
Tell us more!!!
4 rotor 12a.... this is the one we all dream about....
Now thats a project...
What intermediate plates are those?
What are you gonna do about stat. gears for the middle rotors?
heck... are you using tension bolts from either end of the block, or are those just mammoth???????? Going for any bracing on that big daddy, I forsee a bit of torsion there!
Tell us more!!!
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Joined: May 2006
Posts: 715
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From: Holland, Michigan/ Afganistan/ Iraq/ Itatly
Here is another idea!
Oil pump and water pump, do you think the stock pumps can put out enough to lube that beast????
But if you get the e shaft to work i have an extra 5sp Titanium internals tranny. Youll need it.
Oil pump and water pump, do you think the stock pumps can put out enough to lube that beast????
But if you get the e shaft to work i have an extra 5sp Titanium internals tranny. Youll need it.
Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
Jerry, the ghetto e-shaft should be actually pretty easy to build. I already know that in order to get the awesome 4 rotor exhaust note, you need a rotor to fire every 90°. The prefered firing order is 1324 where:
L1 0° (TDC)
L3 90°
L2 180°
L4 270°
I even figured out a ghetto direct fire ignition system (currently leading only*) that will not only fire each plug at the correct time, it will also provide the cool late leading or 'wasted' spark like DLIDFIS and 2GCDFIS that we all know and love.
Very simple, very little to go wrong, based on parts that are easy to get, totally ghetto. I'll get more pictures after I've built it and my camera is working again.
*plans to add trailing are for possible future MegaSquirt project. For now though it will be NA carbed with a dizzy. No real need for trailing right now since it doesn't really do much if you're NA with a direct fire (late) leading ignition. Test it yourself on the dyno some day. You'll see what I mean.
One more picture of the engine bay showing tilt of engine. I think I got it level before constructing the motor mounts.
L1 0° (TDC)
L3 90°
L2 180°
L4 270°
I even figured out a ghetto direct fire ignition system (currently leading only*) that will not only fire each plug at the correct time, it will also provide the cool late leading or 'wasted' spark like DLIDFIS and 2GCDFIS that we all know and love.
Very simple, very little to go wrong, based on parts that are easy to get, totally ghetto. I'll get more pictures after I've built it and my camera is working again.*plans to add trailing are for possible future MegaSquirt project. For now though it will be NA carbed with a dizzy. No real need for trailing right now since it doesn't really do much if you're NA with a direct fire (late) leading ignition. Test it yourself on the dyno some day. You'll see what I mean.
One more picture of the engine bay showing tilt of engine. I think I got it level before constructing the motor mounts.
Joined: May 2006
Posts: 715
Likes: 0
From: Holland, Michigan/ Afganistan/ Iraq/ Itatly
You will have to have a shaft made, you can not weld two togather and balance it.
The centerplates will not wiggle on, you almost need to have a key in lobe something you use some high strenght set screw on.
But if you can work it out more power to you i know you can buy the 4 rotor 4 piece shaft for about 4-5,000.00 dollars.
The centerplates will not wiggle on, you almost need to have a key in lobe something you use some high strenght set screw on.
But if you can work it out more power to you i know you can buy the 4 rotor 4 piece shaft for about 4-5,000.00 dollars.
Thread Starter
Joined: Aug 2001
Posts: 15,725
Likes: 91
From: Near Seattle
openshot, gonna be NA for now with no plans to go turbo. The future is open though.
Nick, that would be too easy. You gotta be able to assemble and tear down the engine.
trochoid, yes I've been doing quite a few projects lately now that the weather is getting better. I always try to do something new if I can, and learn from it. The latest is an '84 automatic 12A car that needed some TLC. The Nikki and mani thread showed the carb and intake that I modded for it. I got some more done yesterday but my camera's battery gave out when I was shooting the progress last night.
No need to cut the firewall. Using 12A rotors, the whole engine is just short enough that no mods are required. Infact even the stock front sway bar is still in place. Can any 2nd gen guys say that with a shorter 20B?
It'll get an RB bar and probably Eibach springs (to help handle the extra weight) after the engine is done.
Gen1onr, GSL-SE intermediate plates because they have motor mount studs on both sides. This project would be more difficult if I was using 2nd gen intermediates because they only have horizontal studs on one side and vertical on the other. Plus the extra length of the 13B rotor housings would complicate things.
The gears can be machined down and the intemediate hole can be machined out a little. That is to say the section of the gear that bolts to the plate can be machined down, not the gear itself. lol SLots must also be added to allow the oil to drain back down into the pan.
Tension bolts, long threaded studs, I'm not sure yet. I've already fabbed a couple to keep the mockup together. Dowel pins too. They only go through the rear plate and thread into the front plate.
The motor mounts will add a bit of strength. I overbuilt them.
13b4me, the distributor will be direct fire only. It'll have a cap but that's just to keep the dust out. I'll mod an '81-'85 and take advantage of the 4 rotor's natural 90° firing interval. I won't spill the secret of just how to do it yet. 
Jeezus, yeah, that's the only way. Those tiny GSL-SE intake ports are too small.
Nick, waterpump, yes. Oil pump, maybe.
We'll use the tranny until it breaks. Same for the rear end. No sense fixing something that ain't broke. Breaking something is half the fun sometimes. It means you had a good day.
twinkletoes, yeah. I bet this thread will get updated fairly often as things progress. I can't post any new info at this time because A: the car isn't here and B: my camera isn't working any more.
I can post one more picture. This is from when I pulled the mockup and tore it back down. It's sitting next to another mockup.
I'll get a picture or two of the motor mounts when my camera is working again.
Ah, some new posts.
Nick, I've got two shafts here to look at. One is the early type with a removeable blind plug. The other is the later type with a staked-in brass plug. If I use them the brass one will be for the rear rotors.
I'm thinking cut a slot to accept a key, machine the opposite ends of two shafts for one to slip into the other, then add a set screw like you said. As long as it's true and can be balanced with four letter C rotors (because C was in the middle of the production weights from A through E) I don't see why it wouldn't work.
Actually with the NZ exchange rate, it costs less to buy a shaft from there.
dubulup, thank you.
Nick, that would be too easy. You gotta be able to assemble and tear down the engine.
trochoid, yes I've been doing quite a few projects lately now that the weather is getting better. I always try to do something new if I can, and learn from it. The latest is an '84 automatic 12A car that needed some TLC. The Nikki and mani thread showed the carb and intake that I modded for it. I got some more done yesterday but my camera's battery gave out when I was shooting the progress last night.
No need to cut the firewall. Using 12A rotors, the whole engine is just short enough that no mods are required. Infact even the stock front sway bar is still in place. Can any 2nd gen guys say that with a shorter 20B?
It'll get an RB bar and probably Eibach springs (to help handle the extra weight) after the engine is done.Gen1onr, GSL-SE intermediate plates because they have motor mount studs on both sides. This project would be more difficult if I was using 2nd gen intermediates because they only have horizontal studs on one side and vertical on the other. Plus the extra length of the 13B rotor housings would complicate things.
The gears can be machined down and the intemediate hole can be machined out a little. That is to say the section of the gear that bolts to the plate can be machined down, not the gear itself. lol SLots must also be added to allow the oil to drain back down into the pan.
Tension bolts, long threaded studs, I'm not sure yet. I've already fabbed a couple to keep the mockup together. Dowel pins too. They only go through the rear plate and thread into the front plate.
The motor mounts will add a bit of strength. I overbuilt them.
13b4me, the distributor will be direct fire only. It'll have a cap but that's just to keep the dust out.
I'll mod an '81-'85 and take advantage of the 4 rotor's natural 90° firing interval. I won't spill the secret of just how to do it yet. Jeezus, yeah, that's the only way. Those tiny GSL-SE intake ports are too small.
Nick, waterpump, yes. Oil pump, maybe.
We'll use the tranny until it breaks. Same for the rear end. No sense fixing something that ain't broke. Breaking something is half the fun sometimes. It means you had a good day.
twinkletoes, yeah. I bet this thread will get updated fairly often as things progress. I can't post any new info at this time because A: the car isn't here and B: my camera isn't working any more.
I can post one more picture. This is from when I pulled the mockup and tore it back down. It's sitting next to another mockup.
I'll get a picture or two of the motor mounts when my camera is working again.
Ah, some new posts.
Nick, I've got two shafts here to look at. One is the early type with a removeable blind plug. The other is the later type with a staked-in brass plug. If I use them the brass one will be for the rear rotors.
I'm thinking cut a slot to accept a key, machine the opposite ends of two shafts for one to slip into the other, then add a set screw like you said. As long as it's true and can be balanced with four letter C rotors (because C was in the middle of the production weights from A through E) I don't see why it wouldn't work.
Actually with the NZ exchange rate, it costs less to buy a shaft from there.
dubulup, thank you.
Last edited by Jeff20B; Apr 1, 2007 at 12:38 PM.
Impressive project! I'm definatly subscribing to this one. I have so many 12a's sitting around I was thinking about trying to make some kind of killer engine out of them, this is good inspiration....
Wow. Words can't describe what a 4 rotor engine sounds like. I have only heard two in my life running. Sounds like a swarm of pissed off bubble bees! Turbo? Holy hell. With a 4 rotor? That would be like puting nitrous on a jet engine!
Newbie
Joined: Jan 2005
Posts: 4
Likes: 0
From: TheNetherlands
Hmmm
Hmm nice build.I do give u hands up for thinking outside the box.No flaming here but alot of people bitch and complain about some one putting a v8 in there and over weighing the front end.Did u stop and think how heavy this thing will be,thats alot of cast iron and Alum there,and u haven't even have the intake and exhaust and other components on.Pls Quote me wrong but a 20b 3 rotor weighs in at around 300kg or700lbs loaded what do u think this 1 will weigh?
Remember no flaming just asking and again nice build
Remember no flaming just asking and again nice build
Newbie
Joined: Jan 2005
Posts: 4
Likes: 0
From: TheNetherlands
Hmmm
Hmm nice build.I do give u hands up for thinking outside the box.No flaming here but alot of people bitch and complain about some one putting a v8 in there and over weighing the front end.Did u stop and think how heavy this thing will be,thats alot of cast iron and Alum there,and u haven't even have the intake and exhaust and other components on.Pls Quote me wrong but a 20b 3 rotor weighs in at around 300kg or700lbs loaded what do u think this 1 will weigh?
Remember no flaming just asking and again nice build
Remember no flaming just asking and again nice build