Sunday, February 6, 2011

Thank You Skunk2

I have a land speed race car. A couple of years ago Tim Kelly from Xact Dyno and I went to the Bonneville Salt Flats to set a land speed record. There are a hundred different classes, the one I compete in is G/GT. The G before the slash is for 1.51 liter to 2.0 liter engine and the GT stands for 2 seat production car with stock exterior. The class divisions are a little more complicated than that, but that's my class rules in a nutshell. There's more information on how the classes break down on the Southern California Timing Association and Bonneville Nationals Inc website if you're curious. 

The existing G/GT record I was running against is 157.805MPH, and was set over 20 years ago by a 1987 Ford EXP. The Ford EXP was a brick so I figured this record was ripe for the picking and I had the perfect combo, A K20Z3 and an Insight. The best 2.0 production motor made in the most aerodynamic 2 seater in production. This wasn't the first time a Honda tried to break that record, In 2002 Car and Driver Magazine made n attempt in a modified S2000. There is an interesting article on the Car and Driver website chronicling their assault on the record. This wasn't my first time either. A year earlier I seized a modified K20A2 engine at around 130MPH. I say seized, but actually only one piston seized. Kinda of funny, it felt like I had hit a really strong headwind. Upon inspection of the engine it appeared the no. 1 piston seized and the crank pulled the wrist pin out the bottom of the piston and then pounded it into shrapnel. This story probably deserves it's own post.

This year would be different though. Tim had tuned the car with some long pulls to simulate what the engine would go through. Bonneville it tough on engines. We broke the record by .064 MPH. I had expected better honestly. I mean I had an Insight with a K20?!?  Thats when I found out the car that held the record had over 400 HP. It was powered by powered by an exotic DOHC "Ford" engine sourced from a race car in England. The Insight only had 200 HP. OK, not so bad after all. 

Here's a video of the record breaking run. It looks boring on video, but driving the car is unnerving. You don't steer a car at that speed on the  salt, you just make suggestions. When the car feels like it, it starts heading in the direction you want. I'm not particularly worried about spinning at high speed, but I do worry about rolling. That would suck.

I'm going back this year to bump the record up a little, but I needed more horsepower. I called my good friends at Skunk2 and talked to Dr. Charles and Aaron Bonk to see what they could do. They were nice enough to suggest some parts to help the stock K20Z3 breath a little better. The first parts I installed were some Skunk2 stage 2 cams, valves and valve springs. A trip back to the dyno revealed a solid gain of almost 20 HP. Sweet. I was still waiting to install two other parts though, the new 06 Civic intake manifold and a 74mm throttlebody. 

We finally had a some time and installed the manifold and throttlebody  a couple of weeks ago. The parts had to be modified a little, the 06 Civic manifold is made for the drive by wire t-body which has a slightly different bolt pattern. Once modified and installed the car went back to Xact Dyno for some Tim-tuning. Here are the results. Click on the image for a larger picture.

The dyno shows three plots, 1) the baseline before modifications, 2) after the cams, valves and springs and 3) after the intake manifold and throttlebody.  The intake and throttlebody netted another 22 horsepower. Whoa, impressive. I was expecting about 10 HP. Granted the actual number has probably  been effected by the weather. By Arizona standards it was cold last week. But seriously, the software is supposed to compensate for that and I've never seen the weather effect one of our cars by more than 4 or 5 horsepower. Well, we'll know better this spring; when the weather gets warm again I'll retest to check the gains. 

But whatever the results, thank you Skunk2. 175 MPH, here I come!

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