amirza786
Senior Member
- First Name
- A
- Joined
- Oct 4, 2018
- Threads
- 87
- Messages
- 3,854
- Reaction score
- 3,947
- Location
- Northern California
- Vehicle(s)
- 2022 Polestar 2, 2010 Lexus IS 350 Sport
That's pretty much what @gtman @PowerPerLiter and a few of us have been trying to say to the newcomers to this forum who just bought and joined or now after owning for a year or two have the urge for more power. Sometimes the car is not even off the dealer lot for an hour and posts start coming in like "What Bolt-on and mods should I do?" or "I want make 350 whp, what's the best way?" They watch some youtube videos and see people like Eman pushing 400 plus whp and they want to do that as well.I've been tuning cars, mostly turbo 4 cylinders, in the 30 years I've been driving (man, I feel old after that confession).
The true point on if it's wise to tune something or not is to examine the platform, because it's extremely variable.
The Si is a fantastic car, but I'd call it a handling platform. If you're shooting for reliable horsepower, the 1.5T is not the best way. From the dual mass flywheel, pitiful OEM clutch, higher ethanol mix causing injector issues, and fuel system headroom (this one plagues the FK8 too), there are lots of things that ramp the risk of failure up.
One guy above was mentioning what camps people are in regarding their risk:reward for tuning. I'd say that is completely dependent on the platform you're referencing. Comparing extreme cases of a very tune-friendly engine vs. one that is not, I would push a Mitsubishi 4B11 substantially harder than I would push a Subaru EJ257. The Mitsu will make 500whp reliably on stock internals. The Subaru will be a ticking time bomb at even 350whp.
Step down to FWD cars in the mid 25k range, the 10th gen Si is a great handler, but I've been in some that had slipping clutches off the dealer lot. In contrast, the VW GTI is not as handling focused, but a DSG version can make much more power than the Si reliably and without hiccup. The Si will be lots more fun on track. The GTI will be a lot faster on the highway tuned with no drama.
Bottom line, we always try to stress that first and foremost, this is an economy engine. If you want to push over 250 whp, you are going to need to build out the engine, clutch, ECU in some cases, fuel delivery, and I am even hearing of transmissions going boom so possibly that as well. My advice to people who buy this car and pay $25K, unless you are an experienced modder who has money to blow, find a used Focus ST or RS or a Type R. Or, wait 10 years when this is your weekend car. If you need a bit of extra power, just go with Ktuner's base tunes or TSP's stage 1 tune, but be aware that you may need to upgrade your clutch if you constantly use the maps that boost above 22 psi (like TSP's stage 1 map 3). Bolt-ons? I say stay away from them except maybe a good quality Performance Intercooler (Mishimoto, PRL etc).
I had the 2018 Si for 1 year (and 3 months ) and I drove it both with TSP's stage 1 tune and stock, and IMO it was fun stock
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