after watching topgear - got me wondering
 

about my 111k Uk Turbo impreza wagon - its a 9year old car now, and pretty much standard apart from centre decat and prodrive rear box - how badly do subarus loose power from say there original 215/218bhp in your experience? Im not sure it it feels slower now because Im just so used to it now or shes in need of some tlc - I like to think I keep it well up together

I did the Oil + filter 1500 miles ago - the plugs have never been replaced since feb07, I'll do these for sure - did the panel air filter last month, what have I missed that I can do relatively easily myself, Im fairly handy with a spanner! - do fuel filters need to be done?

Any experiences or opinions on the above greatly appreciated! :thumb:

I would say depending on how its been driven and looked after over the years - Even so, I'd imagine at least a 30bhp loss over 9 years is to be expected.

thanks, would that be say due to internal wear would you think? and not really an option to claw back that power somehow?

im curious too. Im about to buy a old scoob. Would be interesting what ways people use to get the power back.

Some injector clearner/sonic clean, oil clean, good service new plugs air filter etc?

30bhp? How exactly did you come to that spurious conclusion?

Yeah, just general wear mate. I would imagine the pistons will be nothing like when they were new, plus various other parts after 110k are gonna be worn no matter what oils etc you use!

So, come on then what would you think?

it would have been interesting to know how many miles the top gear project car had on it. I was quite amazed how they found c50bhp from a simple service. Do you remember the 10k supercar challenge, dont think they would have found the lost power then from a simple service !!

Still waiting for the great words of wisdom from gc8.............

this is exactly what I was getting at :thumb: :D

Did he replace the injectors? I thought I heard them saying that was something James was doing.

Would changing 100k mile old injectors for new ones help with BHP?

Maybe it had been really neglected, I mean not serviced for years! It must be an extreme case though espeicially on such a recent car.

Top Gear didn't gain 50 bhp so much as re-found what it should have had in the first place. My 1995 WRX 105,000 miles on it, had lost about 10bhp from when it had left the factory (had 251 bhp when RR'd). Some bhp would have been slightly clawed back because of exhaust and filter mod's, apart from that its standard. Going to have it run again in Dec, this time with full de-cat and FMIC. Early next year I'll be going for a daughter board and re-map to raise the boost a bit - then thats it! Not going any further with this car. Though the missus may end up driving a shiny STI Ver6 if I have my way :lol1: :lol1: :lol1: :lol1:

some valid points there thanks guys, so really you cant get back the lost power just recoup lost power by doing mods, decat remap etc

which service items will up bhp again do you think, is there anything at all in the plugs being old and replaced with new?

I am sure they changed the inlet manifold as well as the injectors

Anything more than 10bhp on a properly maintained 100k UK car and Id be very, very unhappy.

What, even on a 9 year old car?? Engine components wear no matter what oil you use - You can't buy a car of this age and expect it to be 10bhp shy from when it rolled out of the factory! Maybe 30bhp is a bit ott, but would think at least a loss of 20 wouldn't be out of the question.

Are new plugs going to make any difference at all? ie: with initial starting etc - it doesnt run or start badly, is it best course to change them before a problem does occur?

I imagine that the most critical parts that wear are probably the piston rings and bores - after all, this is where the combustion and power comes from. These parts are designed to allow for wear throughout their life, and unless a ring has broken, these should still form a good seal in the cylinder.
Wear to bearings will probably have a negligible affect on power output.
I suppose the biggest areas for improvement are in engine breathing. Gunk in the inlet, matted-up inlet filters and holes in the exhaust would all have an effect. The valves could also get coked up, which would again lead to poor compression.
Finally, the fuel pump and injectors could get tired, but these are also desgined to be able to over-fuel, so should never be maxed-out.

Basically, wear and tear should cause a negligible change in performace - it's all the crap that gets stuck to various bits that causes power loss!

The biggest bonus for most Impreza owners is that we have a turbo. A quick tweek of boost, and magically, ex-factory performance is restored! :)

Well my MY00 with 104k produced 230bhp with:

ninja sports cat downpipe
JR panel filter
Magnex centre & backbox.

So thats about right?

After the remap it was producing 273bhp/273lbft.

So yes, it may have lost a few bhp and the exhaust/filter swap counteracted it - but it can't have lost much surely?

Oh, on Powerstations rollers which are generally considered slightly conservative.

I only have the centre cat removed and a Blitz Filter on MY99 UK turbo and was RR'd at 214.9BHP, can't grumble at all.

Cam lobes also wear and valve springs loose strength.

New plugs will help with a cleaner burn, how much bhp you recover by changing them depends how fubared they are but definately best to keep on top of them. Even if they look ok they break down internally over time as do HT leads.

Like me, mines keeps on piling on the lb's each year.

I've got a JDM my93 81,000 miles, only mod was a Z4 ecu rated at 260ps (256.4hp) and when it was dyno'ed it made 250.1hp so I was really happy with that for a 14yr old car.

on top gear they changed the manifold, full exhaust system and also newer injectors

There were a couple of standard RB5's at a rolling road meet last year that made close to book figures, I think they had about 90K on the clock.

70,000 miles MY99, pro drive B/Box, K+N pannel filter, running 239bhp

What car?

Over the years I have been to many rolling road days and not really noticed any scoob not making the power. If they have it has been something obvious preventing it from doing so.

Provided they are properly maintained they should not lose much power if at all IMO.