posted on October 12, 2011 21:00
Project Miatabusa Part 10:
Tubular Subframes and Engine Mounts, Oh my!
by Dave Coleman
In July, 2010, we posted Part 2 of Project Miatabusa and proclaimed, in a very carefully worded headline, "The engine is in!" "In" was the operative word. Not "installed", or "mounted" or anything nearly as accomplished as that. In fact, we had kinda faked it, hacking away with a plasma cutter to see just what the engine wasn't going to get along with. Let's recap just a bit:
Here's the stock 300-pound cast iron lump wedged in its cozy cradle of steel. Our initial dimensional study was done with a camera and a few IKEA tape measures. This was enough to convince us it would fit.
Our initial test fit started by removing the subframe, aligning the engine with the trans, and then trying to see if the subframe woud fit back in. It wasn't even close. In this picture, the subframe is hitting the engine, and the tape measure shows a massive 4-inch gap between the subframe and its mounting point on the frame rail.
So we did this. Plasma cutters are so much fun. Note that the passenger's side engine mount pad is now gone. There is zero chance of using Miata engine mounts on this thing.
Even though we were just putting the subframe in for a test fit, we still boxed in all the suff we'd cut out, because that's how we roll... At least when we're in Tim's giant fab garden of a shop.
The first problem revealed itself immediately. With the engine and subframe in place, the lowest point on the engine was cozy with (but not quite touching) the back of the rack. The power steering fittings on the rack, though, were in hard contact. When I originally de-powered the rack, I had planned just to plug the hydraulic fittings. With this hard contact, there was no choice but to hack them off and weld up the holes. No big deal, really.
Tuesday, October 11, 2011 10:43 PM
This project is overflowing with awesome. Love your work Dave, can't wait to see video of this getting its first shake-down.
Wednesday, October 12, 2011 1:28 AM
The attention to detail with this project, as is usual with motoIQ, is amazing.
As fun as the early shake-downs are gonna be, I'm really looking forward to a bit later in this car's life. Once all the kinks are worked out you guys will be able to go back to the engine. Those big Suzuki 4 pot bike engines are incredibly well-developed platforms with a frankly ludicrous potential for horsepower with forced induction. 400+ horsepower is a pretty normal figure (ghostrider had himself a turbo hyabusa built that made 499 bhp on euro pump gas).
The thing is, bikes with that much power are pretty much unusable. You can't actually unleash 500 horse on a bike whenever the hell you want. I beleive that with MotoIQ's extra-robust Miatabusa platform this kind of turbocharged performance from the 'busa engine will actually be usable. At least you can get sick burn-outs instead of mega-wheelies that slam you off the back of the bike.
I can't freaking wait to see the Miatabusa roar! I've seen and heard of many, many big-bike-engine-in-a-little-car projects, but none of them ever seemed worth the effort. However I think that this is one instance where the dream really will come to be.
Wednesday, October 12, 2011 3:26 AM
Hey Dave, awesome build. I had been looking at the V8Roadsters subframe for quite a while to do a engine swap into a Miata. I was wondering, if a regular car engine was swapped in utilizing the V8R subframe, wouldn't the oil pan be in the way of the x-brace that you fabricated? A dry sump would remedy this?
Wednesday, October 12, 2011 3:44 AM
You are planning on turbocharging this thing, right?
Wednesday, October 12, 2011 3:54 AM
Still drooling over this. It really is nerds gone wild over there isn't it. On the last page, the top photo with the engine in the engine bay, what's the ratchet strap for?
Wednesday, October 12, 2011 5:51 AM
8695Beaters -> likely that picture was taken when they just had the middle bolt captured on the mount and they were trying to set the final tilt on the engine by measuring the clearances.
the whole thing looks awesome. can't wait to see it in action.
Wednesday, October 12, 2011 6:10 AM
I see merge collector in the hood clearance shot. Please tell me that is leading to turbo in the future!
Wednesday, October 12, 2011 6:10 AM
Yes, it's likely the oil pan would block you from doing the exact same X-brace we did, but you may be able to do something structurally similar either forward of or behind your oil pan. All depends on the shape of your pan.
Marc is right, that was before the mount fabrication was finished. The engine was balanced on a stack of shims and held in position by the strap. The final position on the mounts is basically the same, though.
Wednesday, October 12, 2011 6:16 AM
No turbo yet, but that header was positioned exactly where we eventually want the turbo to go. The plan is probably to slip off the 4-1 collector and replace with a 4-2 collector that feeds a twin scroll turbo salvaged from an EVO.
Exhaust story is coming up, once we finish the back half of the exhaust.
Wednesday, October 12, 2011 7:08 AM
"It really is nerds gone wild over there isn't it" - @ 8695Beaters
Wednesday, October 12, 2011 7:29 AM
When I initially did my particular swap into the miata, I used a modified/notched subframe to BARELY clear the 3" downpipe...
Well, the new setup with its 4" downpipe required a tubular subframe all together. I was thinking of building a one-off, but following similar line of thought as you guys, the V8R subframe was THE way to go. 4" turbo-back exhaust clears real nice now!
Wednesday, October 12, 2011 10:56 AM
Back half of the exhaust?? What, you're not going to use a busa muffler sticking out next to the fender? =)
Wednesday, October 12, 2011 12:21 PM
You mean the exhaust isn't going to end in a Yoshimura? Proven Japanese performance bliss :)
I'm SO excited to see the results of this project and all this talk of a turbo adds a whole new dimension of crazy to the project!
Wednesday, October 12, 2011 2:17 PM
Could you get V8R to build you a custom subframe instead of having to modify them?
Thursday, October 13, 2011 4:54 AM
Holy hell that is a tight fit, awesome work.
Are you guys doing anything with the oiling system, you desperately need to fit at the very least a swinging pickup wet-sump system if not a dry-sump.
If you keep the stock system, I can guarantee you that the engine will munch on itself.
Would also aid with the fitting issues.
Thursday, October 13, 2011 5:42 AM
Any detail paid to the oil pan for baffles? As many forget in FSAE, these engines are made for the engine to lean into the corner with the bike. I know of too many spun bearings from newer teams who overlooked this issue.
Keep up the good work!
Thursday, October 13, 2011 8:01 AM
This is a pretty decent write-up on it:
I'm sure Dave will come up with something...
Thursday, October 13, 2011 12:15 PM
I have no idea if this will be useful, but we utilize Lord mounts on most of our electronics equipment to fight the harsh vibrations of racing applications. When I was clicking around on the site last time, i started seeing mounts and vibe mounts for all sorts of things.
Below is just a link that you can explore the rest of their site. They have a handful of things that may help with this or OTHER people's builds too.
Thursday, October 13, 2011 4:51 PM
Regarding the oil slosh issue, look closely at the third photo on page 1 (the one with the tape measure). We have mounted the cylinders straight up and down, which actually means we've rotated the engine into what would be a wheelie position in the bike. The bottom of the pan is now a deep vee shape, and the oil pickup is down in the bottom of that vee.
Because of this orientation, the crankshaft is farther from the bottom of the sump than it normally would be. We've got roughly 10 inches from the bottom of the crank to the bottom of the vee. We don't want to fill all 10 of those inches with oil, but we can fill a lot of it. The factory fill on a Hayabusa is 3.5 quarts and I've already got 5 quarts in here and still can't see the oil when I pull the stator cover off the front of the engine (the botom of the cover is roughly even with the bottom of the crank).
With this deep Vee sump, I think we're pretty safe from oil slosh, though we do have to be careful not to be overconfident about this, since the empty transmission case does leave a lot of room for the oil to slosh to in right turns.
Friday, October 14, 2011 6:58 PM
The oem Busa trans is pressure fed. With most of that stuff gone, did you block off the un needed sections or just let the oil squirt? I would guess that you have some still feeding the bearings/gears that are still left inside. Maybe this aextra oil provisions can be used for some other useful lubin job like lubin the turbo when it's added?
As for level, with much of the gears/clutch assy gone, I bet there is more empty space to fill with oil. I know some stunt riders who have oil pick up issues with some motors (strange angles/attitudes when wheelie/endoing). Part of the solution is simply higher oil levels and then use a better oil breather. They also have made some better oil pickups depending on bike models. They also aren't looking for max HP like you are.
Saturday, October 15, 2011 9:54 AM
Hey Dave, I was wondering what in your opinion would be the best way to modify/shorten the PPF? In the case of mounting an engine even further back with Miata stock tranny and shorter driveshaft.
Saturday, October 15, 2011 6:04 PM
I say add some simple baffles since you're already stating some concern for 'right hand turns'. It's simple to do and a hell of a lot cheaper than rebuilding an engine and less time consuming than trashing a motor during a track day...
Still loving the project. A lady friend of mine actually just gave up on her VERY clean Miata and wanted to scrap it. Of course I stopped that but am not sure if I need another project.
Keep up the good work!
Saturday, October 15, 2011 7:37 PM
You DO need another project.
Saturday, October 15, 2011 7:54 PM
I doooon't know. Between two GTA cars, several production parts in development and an EG33 powered 93 Impreza LeMons car; I think i'm pretty booked. However I'll probably get it running for her. She grew up with motocross and all. I'l just make another track junky! ;)
Saturday, October 15, 2011 8:00 PM
..as she looks at me across a beer wondering who the hell I'm texting hahaha
Sunday, October 16, 2011 5:39 PM
Scrap a miata?? how sad! What went wrong with it? What's she want to sell it for? =)
Tuesday, October 18, 2011 5:52 AM
Not scrapped, I saved it. It apparently stopped running, so now I get to see what's wrong with it. I'm willing to bet it's something simple.