Throwing My IS-F On A Dyno Made Me Realize How Much Power I Want In My Next Car

"Torque Affair" (torqueaffair)
08/28/2016 at 08:52 • Filed to: None

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 !!!error: Indecipherable SUB-paragraph formatting!!! 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 odometer, 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 added 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 dumb 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.

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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 power must be considered along 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 my happiness is determined by a power to weight ratio of 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? That’s way too many pounds to a horse. No deal!!

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!!!error: Indecipherable SUB-paragraph formatting!!! is about exploring my fascination with cars. I’m always on the lookout for things that interest me in the car world.

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DISCUSSION (18)

LongbowMkII > Torque Affair
08/28/2016 at 09:09

+50hp? HAHAHAHAHAH

Maybe +15hp. With a tune. People way overestimate the power added by bolt ons, at least for n/a engines.

sounds good though :)

Tareim - V8 powered > Torque Affair
08/28/2016 at 09:10

this might be something to cheer you up, just because the manufacturer claims it had 416, doesn’t mean it actually did, for example the GT86 is meant to be 197hp from factory but I’ve yet to come across one that has been dyno’d (stock) that has reached that number they’re usually around 20 hp down on official figures

DipodomysDeserti > Torque Affair
08/28/2016 at 09:42

“Things wither away as they get older and I know my car is a tired, old IS-F that was forced to go faster”

Bro, it’s an 80k mile Toyota with an intake an headers. She’s not tired or old. If the PO didn’t spend any money on a tune then it probably wasn’t making any more power over stock. If they did tune it, then they maybe got another 15hp out of her.

DipodomysDeserti > LongbowMkII
08/28/2016 at 09:46

I thought the author was joking when I read that, then I realized he wasn’t. Fifty horsepower from intake and headers with no tune, huh? Maybe it's running those Lambo headers from Mopar...

Chasaboo > Torque Affair
08/28/2016 at 09:48

Your writing is tortured.

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > Torque Affair
08/28/2016 at 10:06

If a Lexus IS-F is tired and old at 80k, then I don’t even want to know what you’d call the pieces of shit I drive.

Frenchlicker > Torque Affair
08/28/2016 at 10:11

Tired and old at 8 years old and less than 100k miles. I think your tired and old is very different than most around here. That's kind of like when an 8 year old says a 20 something is old.

Torque Affair > Frenchlicker
08/28/2016 at 10:18

Tired and old in the sense that there are lots of rattles, squeaks etc. Still has a lot of life in it, but it’s a car that’s been driven and enjoyed.

Torque Affair > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms
08/28/2016 at 10:19

lol, it’s got a lot of life left in it still, just has a lot of rattles and squeaks and parts of it are falling apart, like interior paneling etc. Nothing terrible.

Torque Affair > DipodomysDeserti
08/28/2016 at 10:19

Well if stock rwhp is 350, then there’s atleast a 26 hp gain without a tune.

That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms > Torque Affair
08/28/2016 at 10:32

Really? That's kinda shocking for a Lexus.

LongbowMkII > Tareim - V8 powered
08/28/2016 at 11:01

Drivetrain losses. If it's only losing 10% from advertised, that'd suggest 197 is underrated.

Tareim - V8 powered > LongbowMkII
08/28/2016 at 11:34

no this was calculated with the drivetrain loss in mind IIRC, actual whp was down around 150 I remember seeing

DipodomysDeserti > Torque Affair
08/28/2016 at 11:44

Not at all. For one, Lexus doesn’t publish stock rwhp numbers, so you have no idea what it is according to them.

Secondly, the only way dynos are useful are directly before and directly after a modification. Using different dynos years apart tells you nothing about whether or not modifications added power because there is a huge variance between dynos.

The proper way to utilize a dyno is to put the car on the dyno to see where you’re at, add your modification and tune, then put your car back on the dyno to see If it added power and to adjust your tune.

That’s the only way to use a dyno in order to see if a modification added power. Adding bolt ons to cars without adjusting their tune is almost always going to net you zero gains. On cars that run speed density type EFI system you can gain some power without tuning, but the IS-F uses a MAF rather than a MAP, so adding mods without tuning isn’t going to do shit. Adding an intake and headers without tuning to an EFI system using MAF sensor can actually cause problems.

One of the benefits of learning to wrench on your own cars is that you actually know what they’re doing when you decide to mod them.

Dr. Zoidberg - RIP Oppo > Torque Affair
08/28/2016 at 11:55

Hopefully one day you’ll find happiness beyond numbers.

My DD has 27+ “pounds per horse,” and that’s assuming it has the same power as when it was new (it does not). Yet I would not trade it for anything.

Frenchlicker > Torque Affair
08/28/2016 at 13:02

I think that may be a sign that it's time to look into replacing bushings and such. Should freshen it up a bit.

sony1492 > That Bastard Kurtis - An Attempt to Standardize My Username Across Platforms
08/28/2016 at 14:02

No, Lexus interiors are fragile. Really the reliable parts of them are the drivetrain and suspension. As they age electrical and interior go to crap. That being said my experiances ar limited to 03 and older.

Manwich - now Keto-Friendly > Torque Affair
04/22/2019 at 16:25

Well actually, I’d say it told you more about the Power-to-weight ratio you want.