Saturday, September 1, 2012

Adding lightness intelligently

"Gotta make it light. Gotta make it light. Gotta make it light." has been my mantra through three grueling days of sweaty, grit-filled, ear-splitting metal removal. I've moved methodically from nose to tail of the stripped-down car removing EVERY. LITTLE. PIECE. ...that isn't absolutely necessary to a race car effort.

This is a truly crap representation of the hundreds of little tabs, brackets, mounting points and reinforcement plates (for things that no longer existed, of course) that were removed. In the end, JUST with the palm-sized and smaller stuff, I filled two and a half 5-gallon buckets weighing a total of 33.5 lb. Yes, three days for 33.5 lb. This may seem insignificant and a waste of time, and it TOTALLY WAS. Though, in a few paragraphs, we'll see that maybe it wasn't. Either way, I"ll never, ever, ever do it again.

Taking all that stuff off took effort. I tried many ways to do it. I found a 100% best way. Let me share. In olden days I grabbed a grinder and wailed away on the spot weld until all metal within 2" was badly mangled and what was left of the bracket fell off.

I have also used a cutoff wheel on an air grinder, which remedied the 'destroy everything' of the grinder and simply cut a huge gash in whatever I was working on. I also universally failed to remove spot welds
For the start of this adventure I bought a spot-weld cutter, direct from the highest quality tool merchant available.
This worked admirably the first time. Then the tip thing snapped off a bit. So I started pre-drilling the center so the centering pin had somewhere to go. This was a lot of effort, as I had to completely drill through whatever I wanted to cut. Using this technique, the spot weld cutter lasted about an hour, or 4% of the car. Eventually, I had broken all the teeth off both sides of the saw portion and replaced the center pin with about four different nails. Conclusion: if you only need to remove a few spot welds, this will work, but you can't take 33 lb of .05 oz brackets off a car with it.

In desperation, I grabbed my box of random drill bits.
Mulling through it, I found these odd drill bits I've had forever.
Whatever they are, they work. No center drilling, fast, last for ever. I only used two for the whole rest of the car, and the first simply broke the little tip drill and I kept using it later on by pre-drilling the center just a little bit. USE THIS! Here is the finished result once the spot weld is removed:
I also admit to grabbing some of the brackets with a pair of pliers and just bending it back and forth until the metal fatigued and the bracket ripped out. Sometimes I did it just to make myself feel better.

Anyway, back to our story. While I was adding all of this massive lightness I was also keeping an eye out for improvements to the car. There are many ways an MR2 can be improved as a track car, because there are many compromises made so a mid-engine car can be a street car.

One of the great things about an MR2 is the absolute lack of storage space anywhere. In an attempt to remedy this, Toyota created the 'frunk', or front trunk, where the engine in a normal car would be. It's exactly large enough to store nothing. The effect of the frunk, however, is that all that cool air passing through the radiator slams directly in a wall. This wall, to be exact:
See the radiator, and the fans? Blowing all that hot air ABSOLUTELY NOWHERE! So, I removed it. It is 100% non-structural, and I won't be hauling any suitcases.
Great, so now we've got all that hot air away from the radiator and into the frunk. Of course, the frunk was sealed to keep said suitcases warm and dry. Our primay means of venting the hot air will be to louver the hood and bend the louvered pieces down into the frunk (coming soon). In addition, I removed large portions of the upper-firewall allowing the air to escape out the back of the hood at the base of the windshield.
The only purpose of this metal was to hide the windshield wiper arms and allow the heater/vent somewhere to pull air from. We'll block off the vent hole into the cabin, and now have lots of room for the hot air to escape at the low pressure zones.

For those of you paying attention, this has the added benenfit of having all the cooling air exiting over the car, as opposed to under it like most front-engined cars. We have effectively increased our down-force and made the entire front of the car act like a wing. I think.

Moving rearward, we have a similar problem in the cockpit. All the oil smoke and gas fumes and oil smoke and tire smoke and brake smoke and oil smoke that wafts past our car collects in the cabin. Being a two-seater, there is really nowhere rearward for the smoke to go and it just billows around, making the driver nauseous and nostalgic for catalytic converters. My solution was to block the rear windows with a sheet of aluminum (not yet done) and vent the very rear-most part of the cabin rearward. The end result is some very cool vent wings at the c-pillar. Note the 'not yet done' part and visualize with me...
The last little problem the MR2 faces is the engine location, you know - behind the seats and in front of the trunk. In a little pocket, all mid-like. Where it gets very, very hot. Toyota tried to battle this with a side scoop and fan, vented engine lid, and complicated cooling routing. In the end, many MR2 teams battle chronic overheating in racing situations. What with our bigger motor leaving less space, this was going to be an even bigger problem. The solution? Get more air to the engine.

This starts with the wide-body concept. We will be pushing the rear fenders outboard approximately 3", leaving us a nice HUGE scoop facing forward. This scoop will collect air and direct it into the engine via these nice new holes in the side of the engine bay:
What was there (yes, pics from the first car)
One side held the stock vent/fan, the other was the fuel fill pass-though. I removed both sides to the corresponding spot welds, and will create curved sheetmetal ducting to send all that nice cool air directly onto the motor.

Once that air has hit the motor, it has to have somewhere to go! Just like in the front, removal of the sheetmetal wall between the engine bay and the trunk is called for. not only won't we be hauling any golf clubs in the trunk, but we really need to remove this to make the giant V6 fit anyway.
Now that we've gotten that hot air into the trunk, it has to have somewhere to go. OUT OUT!!!!
All in all, a well thought out plan to cooling, and structurally non-impacting too. I know there will be naysayers about that, so I will be adding cross-bracing where the old firewalls used to be. To facilitate all this and in preparation for the wide-body work, we removed the rear fenders too:
All the sunroof structure also came out in preparation for skinning over the hole
So, that was adding lightness. All removed items counted (give or take) I removed 53lb from the tub. Compared to the stock curb weight of approximately 2600lb this seems pathetic and a horrible use of three full days work. BUT...

Get this.

I weighed the tub, in this condition. Windshield, back glass and all.. 366 lb!!!!! In the end I removed 12.6% of the weight from the tub. THAT, ladies and gentlemen, is HUGE. Plus, our weight goal is 1500 lb, so it's 3.5% of that weight, not bad. If we can keep that up with every piece of the car, it will be amazing!

If I can keep any of this up it will be amazing.


Bender said...

I am glad to see your going to cross brace the strut towers. Much needed.
You also forgot to include the 5 lbs of grinding matter that you breathed in while do this project.

Leo said...

Don't forget some of the weight you saved, you will be adding back when you add your braces, and ducts, and fenders. ;)

Leo said...

Don't forget some of the weight you saved, you will be adding back when you add your braces, and ducts, and fenders. ;)

Matthew said...

Thanks for offsetting the 30 lbs I've gained since last driving the MR2!

J F S said...

I'll be looking forward to my two 2.5hr driving stints during OUR first race with this MONSTER!