ICEngineering Subjects

Thursday, June 13, 2013

Project Starlet: Drivetrain-Related Things

Somehow, there are only 2 posts about this car even though I feel like I've done a bunch of work to it. It turns out that I've started on a lot of different parts of the car, and since I haven't really done anything to completion, I don't feel ready to report on it. Well, too bad for me; I've done some stuff and if I don't write about it, I'll forget about what it was. On with the story.

Uh...where did I leave off...?

Engine and Transmission

I went through a lot of my trademark waffling when trying to pick a drivetrain for this car. My first thought was to do a 4AGE, since it would be kinda period correct and it's a solid motor, but it's pretty ancient by now. At the other end of the spectrum, it'd be cool to do a small block Chevy because they apparently go with everything. However, an LSx is pretty heavy. I know that's the cliché that people cite when they say that builders are "removing the soul" from some lightweight sports car, and then somebody points out that it's only a 50 lb weight gain over stock or something. Admittedly, those motors are light for what they are, but modern four-cylinder motors are still substantially lighter. In addition, the Chevy V8's need huge transmissions and the giant torque numbers will require something like an 8.8" rear axle (and if you've been following along, you've seen that I've already decided on a dinky little 7" thing).

So with these points considered, I ended up deciding on a Ford Duratec/Mazda MZR inline four cylinder. It's a very light all-aluminum engine with efficient head design and it's ridiculously common. This engine architecture is used in the Ford Focus, Fusion, Escape, Ranger and Transit Connect as well as the Mazda 3, 6, Tribute, B2300, and even the MX-5 Miata (there are probably a few I'm forgetting there too). It also comes in a whole bunch of different variants, ranging from a 2.0L in the Focus and MX-5 up to a 2.5L in later Mazdas. I decided on the 2.3L variant because it seemed like a good size for a turbo motor, and because it's readily available in a RWD configuration from the pickup trucks and those pickup motors don't have balance shafts, so they're a little lighter and more efficient. it wasn't super well thought out, but these engines are popular and frequently used in swaps and in motorsport applications...though mostly in Europe. So I bought an engine out of a 17K mile Ranger from a junkyard. I'd put a picture of the acquisition phase here if I was significantly better at documenting what I do, but I'm not so instead here's a picture of me trying to stuff it into the car!

I also needed a transmission, obviously to do transmission-y things, but also so I could determine fitment in the vehicle. For this, the only longitudinal manual transmissions that bolt right up to your average Duratec are the Ranger 5-speed and the MX-5 5-speed and 6-speed. I decided against the Ranger trans because it has truck-y gear ratios, and decided on the MX-5 6-speed because they're apparently a lot sturdier than the 5-speeds. Heavy though. So I got one of those too.

And even took a picture of it and the box that it arrived in on my doorstep

Eventually, I bolted those two things together, and tried positioning it the way I wanted it in the car. Unfortunately, that transmission is gigantic, so I had to do a lot of uh...clearancing to make it fit.

This gets less ugly later. Not much less though

I bought some polyurethane bushings from some off-road shop, machined a couple of billet mounts for the engine and fabricated a steel thingy for the back end of the transmission. Oh, another detail of this particular transmission is that it uses what Mazda calls a "powerplant frame" or PPF, so instead of attaching the transmission to the body, it runs a huge beam down the length of the tunnel to attach it to the diff nose. My RX-8 actually does this too. What that means is that the mounts on the transmission are weird, so the interface I made for it is weird too.

That tunnel brace will have to be a lot beefier. Also, these photos suck

That's cool. I have a different engine firmly bolted into this vehicle now! Somehow, I also did this in the middle of winter with this much space in the garage:

I suppose I could have turned on the lights for this photo op


Very quickly, oiling became a serious problem for this particular engine/chassis combination. The first problem is that the Ranger uses a rear-sump oil pan, while the Starlet uses a front sump. That means that the Starlet's front subframe (really just a crossmember in this case) exists in space where the oil pan would like to be. The other issue is that the MX-5 transmission demands that the engine be tilted ten degrees toward the passenger's side of the car, so the oil pan would be crooked anyway. The MX-5 pan would be oriented correctly, but the sump clearance problem is even worse. So those pictures of the engine in the car also show the engine with no oil pan. Clearly a problem.

This is the best shot I have of the stock Ranger pan. It's maybe a little ominous

What do you do when nobody makes a pan that will allow you to do the engine swap you want? I don't really know for sure, but my guess is that you cut up the existing pan until it fits and then fix the problem with welding (the way I fix most of my problems). In the photo above, I needed to remove almost everything above that green tape line. Here's a view from the bottom of the car with the pan hacked up to fit:

 Note that you can see into the engine around the middle of the photo

I also had to cut off everything else that was left so I could put a sump up front. I then got to work reconstructing the whole thing.

Incidentally, the oil pickup also had to be relocated from the back to the front, so I left the bottom off the pan so I could see where it was going.

I finished off the bottom of the pan and filled it with water to determine how grossly short of my desired capacity it was. The sump is very small because it's a lot shallower than stock for ground clearance, and the crossmember eats up a lot of the volume I'd like to use. I ended up with something like 3.1 quart capacity, which is less than the 4 quarts that I'd like to see (based on no real science).

Looks nice, but sadly too small

The only option I had at this point to add volume was to add wings to the sides. Wings are a bit of a pain because they make it very difficult to access some of the bolts for attaching the pan to the engine block, so I tried to make sure that I left a decent amount of clearance for fishing bolts in and out. I simply cut some slots the sides of the pan with a plasma cutter (to let oil flow in and out of the wings), bent up some C-shaped things and welded them on.

I also needed a drain plug, and I rather liked the stock arrangement, so I cut that corner off the old sump and welded it on.

A dipstick is a nice thing to have too, and you may notice from two photos above that the dipstick hole in the side of the pan leads to an area that is not inside of the pan itself, so I turned a dipstick bung on the lathe and welded that in...

I then closed up all the holes, checked for leaks and checked capacity again to find that I was just a little over 4 quarts. I'll be running an oil cooler and maybe an Accusump too so I'll have a bit of extra capacity with those. The pan still needs some baffles and a windage tray, so it's not done, but it's at a point where it keeps crap out of the engine and tells me what I need to know about fitment.

Probably the most complicated fabricated aluminum thing I've made to date

On to the next oiling problem! You may or may not have noticed in this picture:

that there is a machined spot with some oily holes in it by the U-joint at the end of the steering column (that thing that looks like a rusty funnel on the right side of the photo). That's where the oil filter take-off used to be. It wants to be right where that steering shaft is, and the filter itself wants to be where the steering rack is. Obviously that won't work either, so a remote-mounted filter is in order. Unfortunately, most filter relocation kits still attach to the existing filter mount, so I would have to make something once again. I also didn't have a whole ton of clearance to the steering system, so it would have to be fairly low-profile. I did some measuring of the stock part, made a CAD model, stuck a chunk of aluminum in the big machine, bought some AN nipples, did some welding and made myself a cool filter take-off. I still need to buy some expensive hoses and a filter mount, but at least I know that the engine fits! Naturally, I have no photos of it installed...

I've done a bit of other stuff too, but this has gotten quite long, so I'll leave it here for now.

Wednesday, March 13, 2013

STX RX-8: Diffs and Dampers

As detailed in the last post, I bought a bunch of stuff. Of course, I don't like to make things too easy on myself, so it wasn't as simple as bolting on the Koni 2812's and sticking the OS Giken diff in the rear end. Let's start with the dampers.

The dampers were mostly good to go right out of the box, but I wanted some work to do. The first thing I did was have my friend Allen (who owns the turbo Miata discussed here) run them on a shock dyno along with my old Koni Yellows so that I could baseline them and determine how healthy they were. I got a bunch of cool charts like this:

This was also helpful because it told me that one of the dampers was a little low on gas pressure. For those who don't know, gas charged monotube dampers like the Koni 2812 have a floating piston inside of them that moves up and down to allow the fluid chamber volume to stay constant as the piston rod enters the shock body through the damper's stroke. The floating piston is pushed on by high pressure nitrogen gas so that when the piston rod leaves again, it doesn't induce vacuum in the fluid which would cause air bubbles to precipitate out and make the damping forces really unpredictable. That's all clear? Good.

I could get the whole set rebuilt at some crazy cost, but since I'm cheap and don't like shipping stuff, I decided to just leave the old fluid since it seems to be damping ok and simply refresh the nitrogen gas charge in all the dampers. That sounds pretty simple, except that to keep a low profile on the damper body, Koni's charge port is just a hole with a bolt in it, which unlike a schrader valve has nothing to to thread a fill tool onto and requires a bunch of rotation of a socket head screw to open and close the "valve."

So I went to Harbor Freight, bought some cheap locking pliers and made a tool!

It's not that clever, since it's just copied from pictures I found of the actual Koni tool.

That upper part with the valve and knob sticking out of it creates a sealed chamber around the fill screw once it's clamped around the shock body, and then the knob is attached to an allen key sealed to the chamber for opening and closing. The idea is sound, except even with the smallest chamber that I could reasonably make, it still required 30+ pounds of pushing against the gas pressure to get the allen key seated in the screw and was also a little bit finicky about sealing against the shock body. So thanks to Allen for dealing with that for me!

So now the shocks are good as almost-new (which is different from almost good as new). Another annoying thing is that the adjusters for the front dampers are pretty hokey looking for super high end shocks. As far as I can tell, damping adjuster knobs are like the pride and joy of many damper manufacturers. They're usually really pretty machined and brightly anodized things. The Koni adjusters are basically nuts.

They're so tiny, I couldn't even turn them by hand!

Given how lazy I normally am, I probably would have just left them. However, one of them was lost in shipping and Koni wants $12 for these things! Really not so bad, but it was an excuse to make something cool. A little bit of machine time later, I had some nice knurled aluminum knobs that I didn't need tools to operate (picture later).

The last thing is actually something that I had put off from last season. I had installed spherical bearings in the rear shock tops, but that was easy stuff because it only needed very basic manual machine operations and a little bit of welding. The fronts would need new top hats made from scratch, so I actually got through about 1/3 of the fabrication on those and then set it aside for some reason. I decided to pick that back up and finish it. I first tried the lazy approach which was to finish them up with only a lathe operation.


But it turns out that shock tops are shaped like almost-triangles for a reason, and the reason is that circles don't fit. So I fired up the big machine and made them nice looking.

With those all done plus the fancy new adjusters, I assembled everything together for a nice photo.

Now on to the diff. This was pretty much just a bunch of wrenching. Step 1 was to take apart everything out back.

I actually disassembled more than you'd need to for just the diff, but I also wanted to change out my wheel studs, which for some stupid reason requires dismantling the rear upright and ruining a perfectly good set of wheel bearings. So Rob and I spent a couple of quality hours with a press doing that...

 This is what happens when you try to remove the hub. The bearing is wrecked.
 But it's nice enough to leave the race stuck on the hub...
 Which needs to be carefully ground off
 Just so I can put in some studs
 Installation is the reverse of removal... 

With that taken care of, we pulled out the diff and swapped it for the OS Giken unit. I really really didn't want to mess with setting lash because the RX-8 uses swappable shims to set both lash and bearing preload, and I didn't want to buy any, so I was just hoping that the carrier-bearing-to-ring-gear-mounting-distance would be exactly the same as stock...

OS Giken on the left, stock Torsen on the right. Height gauge in the back.

Turns out it was! So that was easy enough. We checked the lash just in case, but it of course required no adjustment.

A few hours in the garage later, and we got the rear end all buttoned up again.

That's Rob. People have trouble telling us apart because we're both Chinese.


Now it pretty much just needs an alignment and a wash, and it'll be ready to go a Test-n-Tune in April.

Tuesday, February 12, 2013

STX RX-8: Ramping Up For 2013

The 2013 Solo season is fast approaching, with the first event of the year being a Match Tour in Wilmington, OH on April 6th. That's a national level event at a new highly anticipated site, so it should be very popular and a potentially very demoralizing way to shake off the cobwebs.

In anticipation for things to get going again, I've been buying/making a lot of stuff so hopefully the car will be even better than it was last year. It's costing me a lot of money, so it had better be worth something!

#1: Dampers

I detailed a little bit of the build-out of my single adjustable Koni Sport dampers in an earlier post. That was pretty much the cheapest way that I could come up with to get a decent set of coilovers on the car, and those shocks have served me very well over the past 5 years. They definitely have some issues, like needing to be removed from the rear of the car to adjust rebound (so I pretty much never do it) and not having enough damping to control wheel hop on launch. They are also the same length as stock, though my car is nearly 2" lower than stock, so usable travel is pretty small, and it turns out that there's a reason why the stock spring is so huge in diameter, because the small-diameter race springs rub the shock bodies over bumps. I've dealt with these things for 3 years, so it's not like it's killing me, but my expectations for results have been raised significantly due to the car's performance last year so I was pretty set on a damper upgrade.

At Nationals, I had poked around the paddock a bit to see what kinds of dampers people were running so I could get an idea of what the fast guys did. I decided that I wanted something double adjustable (rebound and compression) and preferably a monotube so I could run the rears inverted and not have to deal with the springs rubbing. Those two requirements immediately put me up in the Moton/Ohlins territory that was greater than $5000 for a set of dampers.

Instead, I decided to take advantage of the modular construction of my existing dampers and I would have them revalved with higher damping rates and converted to double adjustable or at the very least, have the rear rebound adjustment be made external. This would run me about $1200 and wouldn't fix all of my problems, but it captures 90% of the improvement that I was looking for at about 20% of the cost.

This all changed when at the end of October 2012, I stumbled upon somebody on selling a set of Koni 2812's. These are Koni's top-of-the-line double adjustable aluminum bodied monotubes with some extra-fancy proprietary valving arrangement. They weren't cheap, but they also weren't $5000, so I waffled over it for a while like I always do about big purchases and then bought them.

Old vs New
So that's a big deal. I've done a little bit of stuff with these, and that'll be detailed later, but I'm pretty excited to see how this will affect performance.

#2: Limited Slip Differential

Another gigantic purchase that I had been seriously on the fence about is an upgraded differential. The RX-8 comes with a helical-gear Torsen-style differential which is theoretically great and it works pretty well, but it's totally untunable and I don't think that it's quite right for what I need the car to do. This is a tough decision similar to what I went through with the dampers because I know that the existing solution works, but there are better solutions out there. Unfortunately, it's nearly impossible to quantify the benefit of those better solutions, making the cost/benefit ratio indeterminate.

So...I decided to just bite the bullet and get the best/most expensive diff available for the RX-8; the OS Giken Super Lock LSD.

It took me a while to figure out what was going on inside the OS Giken diff that was not happening in other clutch type diffs like Kaaz and Carbonetic, but when I finally got it, I deemed that it was enough difference to warrant the $500 cost difference. I hope that's true. And I'll never know if it is, so it doesn't matter.

In preparation for this, a good friend Rob and I pulled the car out of winter storage (wherein it is nearly touching the south wall of my garage to make room for the Starlet) and stood it up on stands to begin the brutal dismemberment of the rear end of my car (again) so that we can get the diff out.

The car is unbelievably dusty

Again, there will be more on that later.

#3: Wheels and Tires

I've been running on these cheap but heavy 5Zigen FN01-RC wheels in a 17x9 +43 wheels for a few years now. I got them because they are crazy cheap at around $800 for the set. They also look pretty cool, and I got them at the same time that I got wheels for our white Fit so both cars that we had at the time would match.

Somehow I don't have a picture of the two cars together

However, without exception, anyone who has been nice enough to help me change wheels at an autocross has commented on how obscenely heavy my wheel/tire package is. I've been tempted to buy some lighter wheels for a while but just like with the other upgrades, it was difficult to justify the cost when I already had a workable solution. I got lucky when fellow SE Michigan STX RX-8 driver Brandon decided to sell his Enkei RPF-1's at the end of last season so that he could fit a big brake kit. So now I finally have light wheels. Plus they're gold which is super sweet.

And they've been stored in the car since October

As for tires, there is currently a street tire arms race going on with Dunlop and BFGoodrich having already released their latest and greatest ST-legal tires and there have been talks of an entry from Bridgestone and possibly Kumho. I'm not sure what to do about that yet, so I'm going to wait and see if anybody gets some good testing in before I need to buy tires.

So that's a quick overview of what's happening with the RX-8. I'll get more in depth into some of this stuff when projects start getting completed. I really hope the car will be faster!

Monday, February 11, 2013

Two-Strokes and Electrics

Last kart day of the year, Oct 27 2012!

I'm finally getting around to rebuilding the kart, which has been a spectacular autocross and level-1 fun (fun the whole time) success.  The thing's a blast and a workout - driving it helps slow down the other racing, and the physical requirements helps motivate to get stronger.  True, I haven't gone wheel-to-wheel in the kart yet, so I'm certainly no real karter...

My kart reflects that a little.  I got it used, great deal, great working condition, but it's well-worn.  The frame is Trackmagic, a brand known for it's complete lack of support with some odd-sized parts (need to machine a new lower steering column spacer for next season...), and has mismatched knuckles, some welding on it, etc.  The engine fires on the first couple compressions but the inside of it was otherwise a mystery on purchase. 

So rebuilding the engine was interesting, it was the first time I'd seen what modifications are done to it.  The answer is not many...the ports are smoothed, but stock shape and size, transfers are all stock, compression is stock.

As usual, first step is turning working things into piles of gears
Look at all the 2strokes...
Tray 1 of 2. So many parts for such a simple engine!

What's most interesting is the damage found, there's been some fairly impressive detonation history.

Interesting piston damage

I'm still learning what is normal and what is not for this kind of engine and use.  For instance, in the head, I think the damage below is actually normal-ish for extended use!  Comparing the detonation on the head to the piston, I actually think the piston has been swapped after most of that head damage was done, but the previous owner just kept using the old head... let me know if you think otherwise.

Detonation never looked so evenly distributed
Also detonation around top of cylinder, apparently normal (and some lower in the cylinder?...strange)

I ordered a new piston (fancy Wiseco GP, forged) with rings, and I have a new head...that's it for the cranktrain!  It'll go back together with the old cylinder, and the bottom end is good.  Looking for a stock ignition now to get rid of some ballast, and maybe will increase compression ratio by machining the cylinder in the summer if I'm feeling comfortable.  Only thing keeping the kart engine from reassembly is some transmission small parts still on order...about $100 worth of tiny overpriced washers and bushing which I had damaged the first time I ran the kart...without trans fluid...

I'm slapping it back together because again, the purpose of this thing isn't top-level karting, still just practice and experience.  I'd decided to keep this kart and engine going until 4-strokes were legal (expecting 1-2 more years for autocross) and then go in for some nicer stuff.  I am looking forward to racing a kart with less oil burning and noxious pollution.  It would be nice for my interests in car racing and mountain biking to be less opposed, not to mention becoming less of a giant tool who selfishly contributes to ruining the world by purposely running unbelievably polluting things for fun...

However, now I don't think I'll ever go 4stroke.  I think my next kart will be electric. (And yes, I am concerned about battery manufacturing and disposal, jury is still out)

The 86g soft LiPo battery in this costs $7 and is rated to 30amps at 8.4V!  Battery technology is truly improving

After taking custody of one of Kenneth's older RC cars needing only a once-over and a battery, I have been impressed by the capability now so easily available.  The above battery is essentially rated to 1/3 hp, costs $7, and weighs less than 1/5th of a pound.  It's what's called a lithium-polymer battery, a simplified description of its chemistry.  These have disadvantages in their volatility though.  For application in larger packs, a different chemistry is introduced, LiFe.  I don't really know my history, but I understand A123, the highly-government funded company which has gone bankrupt and just been sold to Chinese investors, is primarily responsible for them.  Among many different characteristics, they are also very resistant to becoming...overactive after being damaged.  You could drive a nail through a LiFe battery pack, and wouldn't expect it to react violently.  A LiPo cell would violently burn and burst, and the chemistry we're used to in cell phones and laptops, lithium-ion, would do similar.  The LiFe cells are what's used for the current generation electric cars.  These are the cells in the Chevy Volt, the Tesla Model S (not the old Elise-based roadster, those were the laptop-type) and also in Zero Motorcycles.  Compared to lithium-ion, LiFe also allow for higher discharge rates, similar to LiPoly.  This is good for Zero Motorcycles, and good for aftermarket, because it allows power to be achieved through amperage instead of voltage.  This is a lot safer to people if anything goes wrong and the electricity tries to short though the user.

Power, Watts, is (volts)x(amps): 1hp is 746W, and that can be achieved with any combination of amps and volts.  It's just that with dry clean hands (which have great electrical resistance) under 100V is generally not enough motivation to hurt a person.  300V on the other hand could be much more...fatal.

So we now have the technology in the battery, and the voltage isn't scary.  The hardware is available.  Additionally, the hardware is available assembled, wired, programmed, and even warrantied!  Motorcycles have donated the 2strokes we use in the karts, and now Zero Motorcycles make their electric drivetrains available to anyone.

This is the 2012 stuff.  2013 has much improved battery packaging

After heavily flirting with the idea, I won't be going electric this year.  Maybe in another 2.  The required components currently cost ~$8800 and the battery to power the 44hp 35lb motor still weighs 85lbs.  I'm excited though.  I am lucky enough to know electric cars can be seriously fast, and now with the market moving as it is, I expect batteries will rapidly improve in both discharge rate and cost.

Lucky me, I know electric can be seriously fast.  And this one is ancient compared to the Volt.

For all the bad press, this one is great to drive.  And I partly love it for the battery progress it's driven.