So I’m considering the possibility of purchasing a Lexus IS-F in the next few months, and I’ve been doing a lot of research. (I guess I was just inspired by the Lexus RC-F I recently reviewed) In addition to looking into the car’s seemingly stellar long term quality and reliability, I’ve been checking out what sort of extra performance can be extracted from it with upgrades.
Now, the stock IS-F may well be enough for me, but it’s always nice to know how much more power I could have should I want it. So here’s what I’ve found…
When developing the IS-F, Lexus gave their 5.0L V8 to Yamaha for a high performance overhaul. With high-flow cylinder heads, titanium intake valves, and an 11.8:1 compression ratio, Yamaha got the engine to 416bhp @ 6600 RPM and 373ft/lbs of torque at 5200 RPM. That’s around 330-340hp (rwhp) and around 320-330 ft/lbs of torque (rwtq) at the rear wheels.
Now, 416bhp is nothing to sneeze at, especially at the time when a BMW M3 had 411bhp. That said, it’s reasonable to expect a highly-tuned engine to produce closer to the 100hp/Liter mark than that.
As it turns out, Lexus restricted the breathing of the IS-F’s V8 in the name of noise, emissions, or whatever. Remember, the IS-F was Lexus’ first high performance model, so we’ll just call it a learning curve. But restricted air and exhaust flow means there is power to be gained!
Note on the ECU and Tuning (UPDATED 2016)
In short, the Lexus ECU is was not “tunable” until just recently, after this post originally went up. Some companies have now cracked the ECU and are offering IS-F tunes for $600-$1,000.
Before the tuning was available, owners were able to get by because the ECU will automatically retune itself in a basic way, adjusting to changes from basic modifications. If you open up the airflow coming in and the exhaust flow going out, that will allow the ECU to inject more fuel and make more horsepower. The problem was that the untuned engine was subject to significant power loss in higher temperatures.
The IS-F’s newfound tuning solutions give the car more robust gains in various temperatures and a much smoother power curve. The ECU tune is said to really beef up the IS-F’s midrange performance in addition to the option of a higher rev limiter and a little more peak power. Tunes are available for stock as well as combinations of Intake, Header, Exhaust modified cars.
Intake / Header / Exhaust Upgrades
This is the basic upgrade package anyone wanting more fun from their Lexus IS-F should do because it can be done for around $3,000 or less.
An intake and exhaust should boost the IS-F to around 450bhp (350rwhp) while leaving peak torque around the same as stock, but adding more torque higher in the rev range.
As for headers and exhaust, I’d recommend doing them both at the same time because if you’re going to do one, you might as well just do both and really get your money’s worth.
With both the intake and the full exhaust system freed up to flow better, the Lexus ISF will make around 500bhp, give or take, depending on altitude and fuel quality. Chassis dyno results I’ve seen have been in the 380-400 rwhp range. Factor in around 20% drivetrain loss, and you wind up with around the 500hp mark at the crank. So with the intake / header /exhaust setup, the IS-F finally hits that 100hp/Liter mark, and you know it will sound damn good, too.
EDIT: Now that real ECU tuning is available for the Lexus IS-F, the numbers stated above might even be a little higher, by as much as 20-30 whp, with the car tuned properly.
For my own tastes, I/H/E + tune is where I will stop if I do wind up purchasing an IS-F. 500hp in a nice 3,700lb car is plenty of fun to keep me happy, and I generally like to keep things pretty simple so the car stays reliable. With these simple mods, an IS-F is a low 12, high 11 second 1/4 mile car, isn’t that enough for the street?
But what if 500hp isn’t enough?
Well, you have a cheap option and an expensive option…
Cheap Option: Nitrous
Lexus and Yamaha have built a really good motor here, and it seems to be able to take quite a beating. People have been running Nitrous with great success, running into the low 11 second range in the quarter mile.
Expensive Option: Forced Induction Kit
Obviously the next logical step to the horsepower heavens is a turbo or supercharger kit, but they’re pretty damn expensive, often hard to come by or even custom jobs. You will also need to ditch the stock ECU at this point for a standalone unit. Prices can reach up to around $20,000 for the kit alone, now add install costs, and then ask yourself why you haven’t just bought a Nissan GTR instead…
One cool aspect of many Lexus IS-F turbo setups that have been done is that they feature turbos mounted to each exhaust pipe at the rear of the car. It looks really cool at auto shows, but let’s be honest here, that’s a ton of piping and the lag must be ridiculous.
EDIT: Some of the companies who figured out the IS-F ECU tune are now working on a supercharger kit, so there are great things coming soon.
Handling and Braking
For street duty, the IS-F is already extremely well set up for handling and braking. If you plan to track the car, then you will probably want to get coilovers and beef up the brakes even more. If you’re really just going to be driving on the street, though, I’d recommend driving the car for a while and then seeing what you think needs to be adjusted.
Also, you definitely may want to fit some wider wheels and tires if you’re running your IS-F around 500bhp. Stock it has 225s in front and 255s in the rear. You don’t need to go full widebody kit, but you may want to go with 235s and 265s, or however wide you can without the wheels rubbing.
Limited Slip Differential Swap
Lexus din’t put a proper mechanical LSD into the IS-F until the 2010 model year. The 08-09 cars didn’t have just a straight open diff, but they had an “e-Diff”, which uses the brakes to act like a limited slip diff. How huge of a deal that is will be up to you as the driver, but some folks have swapped in the LSD from the 2010+ IS-Fs.
It’s an expensive job, though, surely a few grand. If you buy the diff from a Lexus dealer the part alone costs $5,000. So weigh your options.
That about sums things up for modding the Lexus IS-F. I think the ideal for most owners is the intake / headers /exhaust + tune setup, with a little nitrous if you really must have even more than 500hp.
The Lexus IS-F is a very solid option, one that will smoke your average “Stage 2” Evo, and will run with some very serious contenders…