Random thoughts

Okay so this may be kind of a dumb question but figured I'd see other legacy owners inputs. I have a 08 spec b, tuned by cryotuning, catted downpipe, and turbo back exhuast. Everything else about it is stock

 

I've noticed lately on my butt dyno the the car feels so sluggish and just not it's normal pull. I'm still building 18.5 to 19 psi sometimes and holding boost properly but the thing feels like a turd. It has been hot outside lately as well, like 95° out. It's a stock intercooler and stock uppipe but the up pipe no longer has the heat shields as that came off in pieces. Does changing to a better intercooler lessen the difference between hot and cold weather? I know the hot weather definitely effects perfomance but is it really that bad?

 

I don't know if this is actually what's going on but no cel and everything is working well, just seems slower than usual lately, pretty consistently with the hot weather too.

Also not sure if this is your problem but heatsoak on these is killer. My outback is a bit more boring but on my 05 sti with plenty of mods it was HUGELY noticeable how much less power it made when it was hot out. The hotter the intake temps the more timing is pulled. There were a few days where it was so bad I thought the motor might be hurt. But at the same time, that thing felt like it made a TON more power when it was 20-30° out.

Have you checked your learning view tables? Mine was sort of feeling like that and it turned out I had a ton of false knock and was pulling like 5 degrees through the main power section.

 

Fixing the false knock and an ecu reset and it felt back to normal again.

 

 

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I'll have to take a look at that and see what it changes. The car has always given me issues with feedback knock and I've searched pretty much all there is to search on this engine. I work at a subaru specialty shop and we've gone over the engine multiple times and cant find anything out of the ordinary. I also worked with dave at cryotune while I was getting my pro tune and the feedback knock was always there and evident. Significantly less after the pro tune but I still see about -4 20 quite regularly. It's been boiled down to the engine just being super worn, previous owners haven't cared for this thing as much as I would have liked so 4th gear synchro is pretty much shot and the engine always gives me feedback knock and knock learning but never shows any issues. The car is on a loan so I actually have a warranty on it so I'm really just waiting for something to FINALLY pop so I can get some of these things fixed.

 

I know it's always had its knock issues but it does that even mid winter so I was curious if heat soaking was what I've been feeling. Or maybe its all just in my head lol

Here’s a good explanation of hot weathers effect on performance.

 

https://www.aet-turbos.co.uk/turbos-and-temperature-summer-weather-and-turbocharger-performance/

Edited July 13, 2020 by DaveWaters

That does do a good job at explaining part of it.

Timing is effected by coolant temp and intake temps. The computer pulls timing when these temps get high to prevent detonation which it’s more susceptible to with the increased temps. You can get away with decreasing the amount of timing lost with fuels like e85 but it will always be there. I’m pretty curious and hopefully someone will chime in but does anyone know exactly what the rate of decay for timing is on the stock tunes? In stop and go traffic I’ve seen the intake temps as high as 220° here and Phoenix and until you get some airflow across that intercooler the car feels like an absolute slug.

That actually did sum it up pretty well. Pretty much exactly what I was thinking but just wasnt sure if it was factual. Hot air expands so everything has to work harder to get the same bang for your buck as cold air. I suppose that does explain how your average person wont notice too much due to tech advancements and it makes you wonder if subaru is just behind in the cooling department lol

I haven’t looked into it so much on these, but I’d really like to see how they perform and are tuned and respond to heat soak with direct injection. I would think it’d be noticeably better since the fuel being sprayed directly into the combustion chamber provides a cooler more controlled combustion which should result in less timing being pulled at higher intake temps. Now I’m going to lose sleep tonight thinking about this.

There actually is credibility to that at least from what I've seen. We work with a lot of different subarus and the direct injection really does help keep things cooler. Newer wrxs can build power a lot easier compared to the older ones simply because direct injection over mpfi. I've seen people with just a downpipe and a tune making sti numbers or more. That's why I'm excited for the new 2022 sti that they hinted at. Claiming 400whp stock from a new fb24 dit engine with every original weak point on the sti (ringlands, connecting rods, etc.) being completely revised for this engine with much beefier components. REALLY hope its actually true