Buying anything from Craigslist is a roll of the dice. You’re never really 100% sure what you’re getting. A brand new couch, is it? Hardly. The “new” couch has been used by three different families, re-upholstered five times and contains buried secrets and stains that put all other secrets and stains to shame.
When it comes to cars, Craigslist becomes a much more expensive roll of the dice. What kind of secrets do Craigslist cars come with? Am I really buying the original car in mint condition or was it in a gigantic crash and then brought back to life with nothing but used, dollar store parts? I’m hoping that the IS-F I bought from Craigslist a few months ago wasn’t pieced back together and is actually the worn out yet accident-free car I think it is.
The IS-F I now own was built in 2008 and came from the factory with 416 hp and 371 lb-ft of torque. But after 8 years, with 82,000 miles on the clock, and a handful of modifications, who knows how much power it really has. I have no idea how much faster it is with the modifications given its age. Things wither away as they get older and I know my car is a tired, old IS-F that was forced to go faster, but maybe doesn’t really want to anymore.
The previous owner outfitted the IS-F with an aftermarket exhaust, intake and racing headers. According to him, these bolt-ons add around 50 horsepower bringing the total output to around 460-470 hp. That’s a lot…but the power is at the crank. Typically there’s a loss in horsepower when it gets to the actual thing that moves the car, so the rear wheel horsepower could be around 400 hp if you factor in a 15% drivetrain loss. Some people think there’s a 20% reduction, some think it’s 12%, but 15% appeared more times in my google searches for “what percentage of people stare at squirrels every day”–and so that’s the number I’m going with.
Using the same logic and formula, a stock IS-F would have about 350 horsepower at the wheel which doesn’t seem like much does it?
I didn’t ask the previous owner too many questions about the modifications aside from the basics. In retrospect, I probably should’ve gotten a more detailed overview of what exactly was done to the car. But I just relied on my expensive pre-purchase inspection to tell me if anything was wrong with the Lexus. If I pay lots of money, I expect to get the right information. In other words, I’m sure I got screwed.
Now that I think about it, I probably should never have purchased a modified car, because if any owner makes their car faster, you can be sure that the car was not “gently driven”. My car probably only had two states of existence: parked or being redlined. Uh oh. The engine and transmission appear to be solid for now, but maybe a blown piston ring is in my future.
But it’s too late now to regret my stupid decision since I already own the car, so I figured I might as well satisfy my curiosity about the IS-F’s true power output by wasting some hard-earned dollars on a dyno session at Eurocharged ATX.
When I showed up to the facility, I saw an S55 AMG, C63 AMG, S63 AMG, a brand new 2017 R8, a modified CTS-V and an Aston Martin. If my car had a soul (he might, I don’t know) and was named Jose, then he may have felt like an outcast and intimidated in the presence of all these high performance, ultra unreliable, over-engineered yet awesome machines. Don’t worry Jose: you can still hang with them because you’re one of the fastest and most reliable 4-door coffeeshop parking lot-sitter around!
Soon after I got there, the IS-F was carefully rolled onto the dyno ramp where it was strapped down like it was going to be tortured. I can’t even imagine the consequences of not securing a car correctly on that machine–surely it would involve a death of some sort. Once the highly capable Eurocharged team made sure no one was going to die, it was time for the torture session to begin.
As the car was floored, it got incredibly loud. I knew the IS-F was loud, but not this loud! The V8 started screaming and there was a second where I thought that the engine might indeed blow. I had to look away in extreme apprehension, hoping that the weary 8 year old, 82,000 miles engine would live through this. But then I realized that I usually push the car much harder than what was going on with the dyno, so there was nothing for me to worry about. Sorry, Jose, for putting you through all that.
After the IS-F howling sessions ended, I waited for the results. It was like waiting to see what you got on a 10th grade history test. “OMG, what did I get? Did I fail? Mom’s gonna kill me!” To me, seeing 400 rwhp on the dyno report would have been an A. Anything less would be a crushing below.
Then I saw the chart.
Noooo! I got a B+! Seeing 376 hp on that piece of paper was disappointing. I was convinced that I had at least 400 hp at the wheels, but that wasn’t the case. But 376 hp wasn’t bad because that means at the crank, the car was generating 442 hp and 412 lb-ft of torque. Those numbers are very close to the specs of a stock 2010 C63 AMG rated at 451 hp and 443 lb-ft of torque, so maybe a B+ wasn’t terrible.
I did learn one thing though. I know that I really enjoy the IS-F’s power driving around town. More could be slightly better, but there is a point where having more power doesn’t mean you can actually use it. My modified IS-F almost hits the mark in that regard. 500 hp is probably too much, 300 is definitely not enough. 400 is just right.
But the power must considered along with with the weight of the car. You could have a 1,000 horsepower but if your vehicle weighs 100,000 lbs then the 1000 horsepower is meaningless. The IS-F weighs about 3800 lbs which means that each horse has to take care of 10 lbs (3800 / ~380 with a bit of rounding up). Therefore, it turns out that the power to weight ratio that makes me happy is 1:10.
Now I know what I need to do. The next time I buy a car, whatever that happens to be, I’ll have to add a dyno test to the pre-purchase inspection. The checklist will contain a line item stating the power to weight ratio.
What’s that? 10.25 pounds to a horse? Ugh, that’s too many pounds to a horse. No deal!