Introducing Colin - a Mini-ature WRX

Pete. (l33t FS) said:

There's.... methods.  Never exceed 65mph unless you can do it at manifold pressure under 15 inches of vacuum.  Never let manifold pressure go over 8 inches of vacuum going uphill.  If you slow down, you slow down.  Basically drive off of the manifold pressure gauge, not the speedometer.

I know, but I can't do it.  If I were to try to keep manifold vacuum that high while climbing hills, I would be in danger and a danger to those around me on the road.  On the up-slopes on I71 that you are well familiar with, I would be down to 45MPH.  In terms of power-to-weight ratio, or at least acceleration, this Matrix is every bit as bad as my Dasher diesel was.  But at least with the Dasher, I could hit 58MPG.  

This thread kinda makes me miss my old Mini coupe.  The Coupe was a two-seater, so it's out of the questtion now--and installing a baby into the back seat of a regular Mini would be unpleasant.  On the subject of MPG, the Mini was hilarious.  I could push into the 37MPG range with very gentle driving, but holy cow watch out if you need to get somewhere.  On my 50 mile commutes from Columbus to Springfield, I could hit that 37MPG if I were on time for work and could drive at 65 (getting positively rattled by traffic moving at least 75.  If I could keep it to 70, I could still manage 32.  If I drove 80, I was 26-28MPG.  It was a steep drop.  I think that's the BMW engine management tuning.  "Oh, you want power, do you? That's gonna cost."

Oh, and air temperature had a disproportionate effect also.  I easily lost 5MPG in cold air compared to hot air.  

Ok, I clearly need to spend more time in the builds forum...

Meanwhile, at the Batcave...

What an unholy pain in the butt to saw up.

The thing about this thread is it makes my Mini build less cool.

I don't know what I can offer to help, but if there is anything let me know. This is pretty awesome.

Srsly guys, I really hope this turns out as awesome as my Vision is.  My Vision went from watching too much Group B footage to watching too much Group A footage   Colin is going to have some pretty cool features that they didn't get in the Group A era, though.

Pete. (l33t FS) said:

Colin is going to have some pretty cool features that they didn't get in the Group A era, though.

 

Anti-lag! Anti-lag! Anti-lag!

And also maybe seat warmers. 

In reply to barefootcyborg5000 :

Antilag was a Group A thing   I am hoping that being an automatic will help a lot, actually.  All that cool noise is very expensive maintenance wise.  Ford had a way to change a turbocharger in under 5 minutes because they NEEDED to!  WRC had a rule that a team may only have one spare turbocharger per car and it had to be carried in the car.

But yes, the computer for the car was one of the first things I bought, even before I had the WRX, because come on. We're going to have FUN with this.  Probably not as explodey as Group A because they were subjected to homologation limitations that we are not, and they had service budgets that we do not.  Practically speaking it will probably be a lot more like a Carberry tune (which uses Subaru's Group N code) than orange turbo post-engine combustion antilag.

F seat warmers.  If anything, I wish there was room for air conditioning.  Or any HVAC at all really.  Fortunately we never run when it is raining, just when it is like 104.

You going to change the torque converter at all?  Get the stall point up into the boost?

What about head gaskets?  I'm sure you have plans to make sure they continue doing head-gaskety things.

In reply to TVR Scott :

All in good time.

Budgetary constraints point to "no" for the torque converter.   I am hoping to be able to use launch control to build adequate boost at the starting line.  It's amazing what a little directed timing retard can do for turbo spool   It should be noted that Ohio regions are strict about no tirespin at the starting line, as it is the biggest site wrecker.  So it isn't absolutely necessary to have 20 pounds when launching because you can't launch.

Besides, if this engine E36 M3s the bottom end, an EJ253 block is going in its place, and a 2.5 has zero problems building boost against the brake compared to a 2 liter.  The difference is dramatic.

If I sat there and waited another five or six seconds, it would have got up to two, maybe even three pounds of boost!  An EJ255 equipped WRX or Forester will happily build 7-8 pounds right away.

When I mentioned to a local that I acquired an automatic WRX for rallycross purposes, he texted back "Are you going to sit at the starting line for twenty seconds like Ed?" 

The other issue with a looser converter, besides the expense, is that higher stall speeds really cook the fluid.  Thermal management is huge in rallycross, so anything that reduces heat is ultimately good.

Berk it.

In reply to Pete. (l33t FS) :

Passenger side seat heater

Weekend 12 day 1 (March 12)

Made a bracket. A big one, and a milestone.

You can almost see it.

I took the Mini subframe home to cut the middle out of the legs because I want to build the control arm mounting points off of them.  So today, those got bolted in.  I then stretched the downpipe out with an expander to fit my S bend in because I am not quite ready to weld it in place yet, but it needed to sit in place while I figured out how to support the transmission.  I wanted to do it in such a way that it also tied the floor together, since I was going to cut the middle out.

A lot of drilling, grinding, cutting, and welding later, I have a combination floorpan brace and trans crossmember.

It clears what is left of the tunnel and the exhaust just peachy.

It attaches with three of the five remaining Mini subframe mounting points.  Will add a second one on the right side later.

Now, 100% of the Subaru drivetrain is supported by bolts and not jacks and hoists.

And now that the floor is held together from underneath, and the transmission position is fixed, next up: Cutting the tunnel apart to figure out how the heck the driveshaft bearing will be attached. The Subaru bracket is wider than the tunnel. Because of the way the Subaru floor is built, I can't just graft the Subaru tunnel in place, too.  And the Mini is narrow enough that there will not be room for seats if the tunnel is widened...

In reply to Pete. (l33t FS) :

Hang it from the roof?

Change to a 1 piece driveshaft?

In reply to maschinenbau :

Absolutely not... the T brace for the diff defines how high the driveshaft can be for clearance reasons.  Subaru has a CV joint in the middle because they run the front half of the driveshaft at almost the same 8 degrees as the engine/trans and they run the rear half at close to horizontal like the rearend, to clear the T brace (which has to clear the fuel tank, which has to clear the floor).

Upshot being, a 1 piece driveshaft will have a lot of clearance issues.

"But you are building the car, you can MOVE the T brace!"  Yeah, I could... but it would require raising the fuel tank even higher, and modifying the floor even more, because the inside height of the T brace actually perfectly matches the rear of the center tunnel in the Mini.  And modifying that part of the shell is not something I am looking forward to because Chrysler/BMW/Rover/whoever is at fault decided to stamp that part of the kickup out of like 30 gauge steel instead of the 22 gauge everywhere else.  It welds like suturing a butterfly wing.

Other factors: I have had a lot of bad experiences with long thin driveshafts in the RX-7.  Even Mazda used to convert them to 2 piece units for harmonics reasons.

Also, a one piece driveshaft will run about $600-700.  Even if it would work, I am NOT spending that kind of money on a driveshaft, period.  I'm fretting over how much the front struts will cost and that is looking like about $360...

This build excites me waaay more than it should....

Weekend 12 day 2 (March 13)

Removed the driver seat, half mounted the fuel tank, removed the airbag module bracket (lots of spot welds!) to make tunnel mods easier.

Then set about the elephant in the room... the driveshaft.  It is next.

I thought I wanted to make it 4 1/4" shorter.  First, grind through the weld...

Mark a straight line so it gets clocked correctly...

Finish grinding the weld, realize you ground through in the wrong spot, and you did not find the shoulder that the tube sits against, realize you should have done this on the lathe, spend a ton of time trying to get the yoke centered in the lathe after reconfiguring the three jaw chuck, wish you had a four jaw chuck, scratch head at trying to convert the drill chuck to a live center, start cutting metal, wish the lathe had a way to lock down all unused axes...

Go back to garage, measure 4 1/4", start cutting with the exhaust chain-cutter that you went to every store in Cleveland to find, find that it could not cut a wet fart, switch to angle grinder and use the chain cutter's groove as a guide...

Press yoke into driveshaft...

Offer up to car, find that it is a half inch shorter than you'd wanted but it'll work okay, pray to the gods of Lincoln and Miller that you don't berk up the weld...

If this fails, I'll have Henderson do the next one.

Dang, I'm not ballsy enough to weld my own driveshafts...yet. For Datsaniti, I changed from a 2-piece to 1-piece since I removed so much wheelbase and didn't want to figure out the center bearing problem you are facing. Shop did it for $250. I probably would have spaced the front subframe down to flatten out the engine angle, and spaced the rear subframe down to match, which would have raised ride height though (or done funky things to axle angles). But looks like you're getting it done, and without making those compromises. I love watching this progress. The exhaust reminds me of my Miata's "passenger floor bump" where the cat is.

It's for a wrx drivetrain, so it's not like it'll really be doing much most of the time.

maschinenbau said:

In reply to Pete. (l33t FS) :

You talking about flipping the transfer case so the rear output points forward? That's... just crazy enough to work... The bolt pattern looks rectangular (therefore flippable), only problems would be clearance to the oil pan and running the rear diff up front, which means it would be upside down. 

Anyway, awesome progress, looking forward to more

If you found an Audi rear diff with the right ratio, apparently they are usually spun the other way, so wouldn't have to be upside down.

In reply to Gammaboy :

They don't have Haldex type couplers, though.

In reply to maschinenbau :

The subframe IMO is already too low.  Lowering the roll center in the front kills the handling, something I painfully learned with the black RX-7.  So a lot of time has been spent trying to ensure that the suspension is as similar as possible to its location in a Subaru.

Keeping the drivetrain at its design angle is also important to ensure oil and coolant work as designed.

Besides, a one piece driveshaft would be far too long unless it was made out of 3" tube.  Expense, expense, expense.

Pete. (l33t FS) said:

In reply to Gammaboy :

They don't have Haldex type couplers, though.

Does the Honda? 

Haldex is a pain in the arse on Audi TT/Golf R32s. If the Honda trans used a conventional centre diff, and the pto could be re-clocked, then the Audi diff would work for a group B style layout...

Gammaboy said:

Pete. (l33t FS) said:

In reply to Gammaboy :

They don't have Haldex type couplers, though.

Does the Honda? 

Haldex is a pain in the arse on Audi TT/Golf R32s. If the Honda trans used a conventional centre diff, and the pto could be re-clocked, then the Audi diff would work for a group B style layout...

Honda does not have a center diff in anything.

I actually prefer that setup, but this is neither here nor there...

TIL how to successfully use a spot weld drill bit.

This would have been good to know TWO MONTHS AGO.

Now. How the heck am I gonna do this.