Has anyone had a 2.5 STi that hasn't crapped itself??
Discussion
There’s 4 in the group I used to be in that failed (all STi’s) and were completely standard and under 50k miles. If the cars were heavily modified or driven badly you could understand but they were all owned by guys who actually didn’t drive them very hard and are very mechanically sympathetic. All cars were completely standard, no air filter, exhaust or anything else.
There has also been tons on Scoobynet and Nasioc over the years that have failed although the numbers seem a lot lower than the 8-11 cars. I have no idea of the numbers but in my experience it’s happened far too many times. It’s worth pointing out though the cars on the forums may have been abused or mistreated, it’s the internet afterall.
It’s such a shame because otherwise it’s a good engine for the road.
There has also been tons on Scoobynet and Nasioc over the years that have failed although the numbers seem a lot lower than the 8-11 cars. I have no idea of the numbers but in my experience it’s happened far too many times. It’s worth pointing out though the cars on the forums may have been abused or mistreated, it’s the internet afterall.
It’s such a shame because otherwise it’s a good engine for the road.
Edited by Scobblelotcher on Saturday 13th January 14:16
It's also interesting that I've read that many of the failures in the USA were on n/a versions. Although I doubt they'd ever release the figures I'd love to see Subaru's stats on warranty claims year by year on this engine. They sell by the shed-load in the USA so it would hopefully have some statistical relevance. I doubt it's anywhere near 'most' or even 'many' engines failing.
Scobblelotcher said:
If the cars were heavily modified or driven badly you could understand but they were all owned by guys who actually didn’t drive them very hard and are very mechanically sympathetic.
That makes it even worse if these engines can pack in with such driving. How would these engines/cars fare with harder use such us the odd trackday or high speed runs on the autobahn?Edited by Scobblelotcher on Saturday 13th January 14:16
Olivera said:
Scobblelotcher said:
If the cars were heavily modified or driven badly you could understand but they were all owned by guys who actually didn’t drive them very hard and are very mechanically sympathetic.
That makes it even worse if these engines can pack in with such driving. How would these engines/cars fare with harder use such us the odd trackday or high speed runs on the autobahn?Edited by Scobblelotcher on Saturday 13th January 14:16
I was surprised to read the new Impreza used for the Isle of Man TT event still had the same problem and they had to use the fog light ducts and some piping to funnel air into the inter cooler. Whenever I modified mine and did track days I always switched to a front mount as not only could it keep the air cooler but it also supports more power.
Most Impreza’s however don’t experience prolonged high speed running so it’s not an issue for most.
Scobblelotcher said:
Olivera said:
Scobblelotcher said:
If the cars were heavily modified or driven badly you could understand but they were all owned by guys who actually didn’t drive them very hard and are very mechanically sympathetic.
That makes it even worse if these engines can pack in with such driving. How would these engines/cars fare with harder use such us the odd trackday or high speed runs on the autobahn?Edited by Scobblelotcher on Saturday 13th January 14:16
I was surprised to read the new Impreza used for the Isle of Man TT event still had the same problem and they had to use the fog light ducts and some piping to funnel air into the inter cooler. Whenever I modified mine and did track days I always switched to a front mount as not only could it keep the air cooler but it also supports more power.
Most Impreza’s however don’t experience prolonged high speed running so it’s not an issue for most.
And there are plenty of Subaru's that ran high speed for prolonged periods without issues, and classics probably had the worst air intakes of the lot, the new cars are much better and more aerodynamic than the previous models
and the new age coped very well with air flow over the intercoolers (they used a splitter in the scoop to divert more air onto the intercooler).As I said it takes a constant power run to do it so most never actually see it.
I was just surprised it still affected even the latest models which as you rightly pointed out are more aerodynamic, still Subaru probably view it as unlikely since most do not stay on the power for long enough to see it.
https://jalopnik.com/in-pursuit-of-a-perfect-lap-a...
I was just surprised it still affected even the latest models which as you rightly pointed out are more aerodynamic, still Subaru probably view it as unlikely since most do not stay on the power for long enough to see it.
https://jalopnik.com/in-pursuit-of-a-perfect-lap-a...
tonyb1968 said:
Scobblelotcher said:
Olivera said:
Scobblelotcher said:
If the cars were heavily modified or driven badly you could understand but they were all owned by guys who actually didn’t drive them very hard and are very mechanically sympathetic.
That makes it even worse if these engines can pack in with such driving. How would these engines/cars fare with harder use such us the odd trackday or high speed runs on the autobahn?Edited by Scobblelotcher on Saturday 13th January 14:16
I was surprised to read the new Impreza used for the Isle of Man TT event still had the same problem and they had to use the fog light ducts and some piping to funnel air into the inter cooler. Whenever I modified mine and did track days I always switched to a front mount as not only could it keep the air cooler but it also supports more power.
Most Impreza’s however don’t experience prolonged high speed running so it’s not an issue for most.
And there are plenty of Subaru's that ran high speed for prolonged periods without issues, and classics probably had the worst air intakes of the lot, the new cars are much better and more aerodynamic than the previous models
and the new age coped very well with air flow over the intercoolers (they used a splitter in the scoop to divert more air onto the intercooler).Not sure how many miles i did around the ring, maybe 300 laps in the Impreza STi5 RA, all the time i had a charge temp gauge on the dash, never a problem even at over 150MPH. That was doing circa 8 minute laps on normal road tyres and stock 280BHP.
The Isle of Mann car driven by Mark Higgins uses a FMIC/Radiator combination similar to the WRC car, not the stock location TMIC. It uses the TMIC scoop to feed the inlet air filter assembly. If that wasn't working at speed they wouldn't use it.
Isle of man record car engine bay
Once you start pushing up the boost on the TMIC, the stock recirculating BOV starts to crack open and passes heated air back into the inlet of the turbo, this generates a viscous circle where the air inlet temp climbs, which means the turbo has to work harder to compress the air, turbo speed goes up as does heat generated, which heats the TMIC, then some of that hotter air gets passed the BOV and back to the turbo inlet..............The AIT sensor is in the MAF, so the ECU doesnt know the inlet air is getting hotter as the air that passes the BOV gets fed back in after the MAF sensor, so cant compensate for it. So when you up the power by anything worth talking about its worth fitting an uprated recirculating BOV with a higher spec to resist the higher pressure.
Its also worth bearing in mind if you replace the stock inlet system, it screws up the MAF sensor calibration because the airflow over the sensor changes, just rotating the MAF sensor housing will change the reading. Fitting a CAI or even just a cone filter to a stock car is dumb and will screw up the engine mapping and fuelling. If you do that dont cry when the engine fails, its your fault.
There was a problem with the MY99/00 MAF sensor, it is very susceptible to false reading if you use an oiled air filter even in the stock housing, always use a dry filter with these (the genuine STI GroupN panel filter is the best). Even stock the MY99/00 MAF should be treated as a service replacement item every 12K miles (just the sensor, the housing is retained, costs about £70). They tend to read lean as they age. The very early hot wire items and the later newage items onwards are fine.
Most problems with these engines are down to crappy modifying or maps, some stock 2.5's have been known to fail, its usually the piston ring land that collapses when that happens. The early 2.5's had issues with the heads lifting causing the gaskets to leak, as stock they had a bottle of radweld poured in as part of the service.
Someone mentioned earlier in the thread the 2.0 and early 2.5 use the same block, they don't, all the 2.5's use a larger bore block than the 2.0. The wall casting thickness of the bore is thinner on the 2.5 than the 2.0, which is why they tend to give up sooner when pushed hard as the bore changes shape. Even the 2.0 was improved later on, the hatchback onwards 2.0 uses a thicker wall casting than the earlier 2.0.
Imteresting post however Higgins was having heat problems with the road spec STi not the later Prodrive beast you mention and have pictured which is a purpose built race car.
Higgins is the one who mentioned the road car was over heating at speed and had secondary ducts fitted, this isn’t my opinion it’s a statement from a very well respected race driver.
Higgins is the one who mentioned the road car was over heating at speed and had secondary ducts fitted, this isn’t my opinion it’s a statement from a very well respected race driver.
Scobblelotcher said:
Imteresting post however Higgins was having heat problems with the road spec STi not the later Prodrive beast you mention and have pictured which is a purpose built race car.
Higgins is the one who mentioned the road car was over heating at speed and had secondary ducts fitted, this isn’t my opinion it’s a statement from a very well respected race driver.
You cant put more air through the intercooler on a TMIC equipped car via secondary ducting.Higgins is the one who mentioned the road car was over heating at speed and had secondary ducts fitted, this isn’t my opinion it’s a statement from a very well respected race driver.
The most likely issue was actually oil cooling on the early attempt cars, which were more based on the production car, IC temps it would not have been, air is seriously ramming through there. That's why even on the 2016 car they used that scoop for feeding the inlet air to the turbo, it works even at 180MPH.
Quite often its the journalists who don't understand the subject or the teams giving false information that you see in public domain, rarely do you find out what the truth is from a motorsport press release or article.
The reason they stopped running short in 2016 was down to oil pressure issues, they knew they had problems, hence the acusump unit on the engine bay side (that blue cylinder), after that they fitted a dry sump system onto the engine for the 2017 nurburgring record attempt car.
Well I guess the statements weren’t fully specific other than running at sustained speed caused power loss although I do recall reading at the time air flow at speed was the (reported) issue however I suppose the articles could be incorrect?
Separately I used to lurk on Scoobynet a lot and I presume this is you discussing with Andy Stevens of ESL fame the subject?
https://www.scoobynet.com/954531-bhp-difference-tm...
www.enduringsolutions.com/fmic-vs-tmic/
Separately I used to lurk on Scoobynet a lot and I presume this is you discussing with Andy Stevens of ESL fame the subject?
https://www.scoobynet.com/954531-bhp-difference-tm...
www.enduringsolutions.com/fmic-vs-tmic/
indeed.
Andy's theory on his FMIC v TMIC is flawed.
All heat exchangers rely on airflow through the core and the efficiency of that core to transfer heat energy into airflow. It doesn't matter where that heat exchanger is located.
The issues revolve around the correct sizing of the core for the efficiency of that core material to manage the amount of heat generated in the air which is compressed by the turbo, all you are doing is cooling down that charge air. The limit of what a TMIC can do is not based on its location, its based on its size and efficiency for the amount of work it is being asked to do. If you maintain the airflow, you maintain the efficiency, there is no airflow issue with the TMIC, air continues to flow through the core at high speed.
The problem with the stock TMIC is that you can ask it to do more work than it was designed to do, its not that the air flow to it stops working. Once you get to the point that the stock TMIC isn't good enough, you then have to improve that by increasing the size of the core or change it for a more efficient design. Most people opt for a FMIC because its cheaper to put a big core up front than building a highly efficient core TMIC. The core design in my TMIC is very expensive but its highly efficient. Most FMIC cores are garbage, they are relying on using a much larger surface area to make up for the crappy cores they use. The stock TMIC is using a cheap production core material, designed to cater for the load it will see in the environment the car was designed for. The problem isn't the scoop aerodynamics.
Both TMIC and FMIC suffer from heat soak when no air is flowing through them. With a TMIC you get heat from the engine and turbo rising which increases its core temperature whilst stationary, for example queuing for the start of a sprint. You get the same problem with a FMIC, but with that the heat is radiated by the water radiator. I've found from dataloging that the FMIC is worse than the TMIC in this situation.
For example at the sprint i did at Teeside where i logged both my car and a friends, my TMIC heat soak from queuing for 20 minutes rose the initial ACT to 44 degrees C on the start line, my friend with one of the best FMIC on the market saw his rise to 57 degrees.
Sprinting is as bad as it gets for intercoolers, because of the heat soak issues as you queue for the start, on the road is more representative of the environment they operate in the majority of the time. Circuit work in Time Attack, racing or trackdays is the next most representative. In those environments you get the opportunity to remove the heat soak from the core before asking them to do the work of cooling the charge air.
So long as the core is sized correctly for the work it needs to do, it doesn't matter where that is located so long as the airflow through it is maintained. This is why on the F1 cars i race prep, the radiators can be anywhere, some early cars have them in the front (very draggy and inefficient), some are in the back at 90 degrees to the airflow, parallel to the engine, (very low drag but inefficient) most are in ducted sidepods as flat to the floor as possible to maintain airflow whilst lowering CofG. (low drag and highly efficient)
The FMIC that work best are not installed as most road cars do, they sit in their own airflow with ducting on the exit to speed up the exit airflow, the water radiator is mounted either below or to the side of the intercooler. You dont stack them on top of each other with the air having to pass through both cores, that's crap for drag and airflow efficiency. Stick an aircon rad in there too and it gets even worse. You often see back to back tests on rolling roads, but the airflow to the TMIC is usually appalling compared to the real world.
Andy's theory on his FMIC v TMIC is flawed.
All heat exchangers rely on airflow through the core and the efficiency of that core to transfer heat energy into airflow. It doesn't matter where that heat exchanger is located.
The issues revolve around the correct sizing of the core for the efficiency of that core material to manage the amount of heat generated in the air which is compressed by the turbo, all you are doing is cooling down that charge air. The limit of what a TMIC can do is not based on its location, its based on its size and efficiency for the amount of work it is being asked to do. If you maintain the airflow, you maintain the efficiency, there is no airflow issue with the TMIC, air continues to flow through the core at high speed.
The problem with the stock TMIC is that you can ask it to do more work than it was designed to do, its not that the air flow to it stops working. Once you get to the point that the stock TMIC isn't good enough, you then have to improve that by increasing the size of the core or change it for a more efficient design. Most people opt for a FMIC because its cheaper to put a big core up front than building a highly efficient core TMIC. The core design in my TMIC is very expensive but its highly efficient. Most FMIC cores are garbage, they are relying on using a much larger surface area to make up for the crappy cores they use. The stock TMIC is using a cheap production core material, designed to cater for the load it will see in the environment the car was designed for. The problem isn't the scoop aerodynamics.
Both TMIC and FMIC suffer from heat soak when no air is flowing through them. With a TMIC you get heat from the engine and turbo rising which increases its core temperature whilst stationary, for example queuing for the start of a sprint. You get the same problem with a FMIC, but with that the heat is radiated by the water radiator. I've found from dataloging that the FMIC is worse than the TMIC in this situation.
For example at the sprint i did at Teeside where i logged both my car and a friends, my TMIC heat soak from queuing for 20 minutes rose the initial ACT to 44 degrees C on the start line, my friend with one of the best FMIC on the market saw his rise to 57 degrees.
Sprinting is as bad as it gets for intercoolers, because of the heat soak issues as you queue for the start, on the road is more representative of the environment they operate in the majority of the time. Circuit work in Time Attack, racing or trackdays is the next most representative. In those environments you get the opportunity to remove the heat soak from the core before asking them to do the work of cooling the charge air.
So long as the core is sized correctly for the work it needs to do, it doesn't matter where that is located so long as the airflow through it is maintained. This is why on the F1 cars i race prep, the radiators can be anywhere, some early cars have them in the front (very draggy and inefficient), some are in the back at 90 degrees to the airflow, parallel to the engine, (very low drag but inefficient) most are in ducted sidepods as flat to the floor as possible to maintain airflow whilst lowering CofG. (low drag and highly efficient)
The FMIC that work best are not installed as most road cars do, they sit in their own airflow with ducting on the exit to speed up the exit airflow, the water radiator is mounted either below or to the side of the intercooler. You dont stack them on top of each other with the air having to pass through both cores, that's crap for drag and airflow efficiency. Stick an aircon rad in there too and it gets even worse. You often see back to back tests on rolling roads, but the airflow to the TMIC is usually appalling compared to the real world.
I’ve had 2, probably not the best to comment as they were fully built but imho if you’re planning on keeping them standard then t probably boils down to how you drive and how well you look after them.
Personally though, it’s better having them built or purchase one that’s already built.
My hatch was fully built running 361/400 on the std turbo, no issues whatsoever, regularly serviced and the oil level checked religiously. Perfect for a daily with the grunt of the 2.5, far better than the ej20 in that respect.
On my track/sprint car (bugeye) I’m running a ej25 with 20 heads, fully built and again, it’s frest. It gets abused and it’s still going strong - touch wood 👀
Personally though, it’s better having them built or purchase one that’s already built.
My hatch was fully built running 361/400 on the std turbo, no issues whatsoever, regularly serviced and the oil level checked religiously. Perfect for a daily with the grunt of the 2.5, far better than the ej20 in that respect.
On my track/sprint car (bugeye) I’m running a ej25 with 20 heads, fully built and again, it’s frest. It gets abused and it’s still going strong - touch wood 👀
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