Help - disappointing power after mods
22 November 2010, 10:05 AM
#1
Help - disappointing power after mods
I have a 2002 sti with the following mods:
Turbo back decat H & S exhaust, green panel filter, walbro pump, TD05 20g turbo, Harvey up pipe and ported headers, 3 port boost solenoid. Opinions on what these mods should produce range from 350 to a 400bhp.
Prior to the 3 port being fitted JGM mapped the car to 338bhp, saying the engine was refusing to accept the timing that would push the power levels up to where they ought to be. With the 3 port fitted a further remap made a miserable 318bhp and had everyone scratching their heads.
I can't be the only one (I hope!) who has had similar outcomes - any ideas? I want to sort it out but would like to start at the less expensive end of the investigation first. All help gratefully received!
Turbo back decat H & S exhaust, green panel filter, walbro pump, TD05 20g turbo, Harvey up pipe and ported headers, 3 port boost solenoid. Opinions on what these mods should produce range from 350 to a 400bhp.
Prior to the 3 port being fitted JGM mapped the car to 338bhp, saying the engine was refusing to accept the timing that would push the power levels up to where they ought to be. With the 3 port fitted a further remap made a miserable 318bhp and had everyone scratching their heads.
I can't be the only one (I hope!) who has had similar outcomes - any ideas? I want to sort it out but would like to start at the less expensive end of the investigation first. All help gratefully received!
22 November 2010, 10:28 AM
#2
Hi - guess we met on Friday...shared your disappointment at the time and it was very odd 
It was holding boost OK, so unlikely to be an inlet side air leak or anything, but the fact that the results got worse between the two dyno sessions does suggest something is failing.
Having heard the engine on the dyno, my first port of call would be to check the exhaust system for leaks as it didn't sound quite right to me. When my engine was putting out 460bhp, I went on a rolling road day and found power was struggling to hit 400bhp - turned out I had blowing manifold-to-head and uop-pipe gaskets.
If they check out OK, I would then check compression - easy enough to do yourself if you're handy with a spanner and have a compression tester (if not, they're about £20; or get Len to check it from you).
It was holding boost OK, so unlikely to be an inlet side air leak or anything, but the fact that the results got worse between the two dyno sessions does suggest something is failing.
Having heard the engine on the dyno, my first port of call would be to check the exhaust system for leaks as it didn't sound quite right to me. When my engine was putting out 460bhp, I went on a rolling road day and found power was struggling to hit 400bhp - turned out I had blowing manifold-to-head and uop-pipe gaskets.
If they check out OK, I would then check compression - easy enough to do yourself if you're handy with a spanner and have a compression tester (if not, they're about £20; or get Len to check it from you).
22 November 2010, 10:47 AM
#4
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i had issues with my car when i was running a md321T but i was on a 2004 WRX engine. so i knew i wouldnt make the magic power figs i was wanting.
Never the less i struggles to get any were past 400bhp. for the same reason, it just wouldnt take any more ignit timing, i replaced the plugs and coil packs and hey presto for soem reason it sorted its self out
Never the less i struggles to get any were past 400bhp. for the same reason, it just wouldnt take any more ignit timing, i replaced the plugs and coil packs and hey presto for soem reason it sorted its self out
22 November 2010, 01:29 PM
#7
Thanks for the responses guys; hi Tim, yes that was me on Friday, hope your car mapped ok? You're right about the sound of the car, since the ported headers and up pipe were fitted the car has not sounded quite right so maybe there's a leak somewhere. I'll get Len at S4U to do a compression check too.
Re the turbo I got that from Harvey along with the ported headers and up pipe so not an Ebay Chinese special.
Re the turbo I got that from Harvey along with the ported headers and up pipe so not an Ebay Chinese special.
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22 November 2010, 02:44 PM
#11
From TD05-20G just 338BHP?
That's shocking result,this power figure you can get from "good one" VF35.
This 338BHP is not WHP(at wheels)?
With your current setup my guess will be around 370 or 380BHP,not 338BHP.One guy from SurreyScoobies get from TD05-18G around 360BHP.
That's shocking result,this power figure you can get from "good one" VF35.
This 338BHP is not WHP(at wheels)?
With your current setup my guess will be around 370 or 380BHP,not 338BHP.One guy from SurreyScoobies get from TD05-18G around 360BHP.
22 November 2010, 07:28 PM
#12
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id defintley get the car up on some ramps and check for leaks on your uppipe gaskets and dwon pipe as well and even signs of the header were they join the heads and maybe chekc your tmic pipes for splits
22 November 2010, 08:15 PM
#14
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I had problem before as well, went through two turbos, and still no power.
But headgaskets went and swapped engine instead, and made good power.
Not sure why, just one of those things.
But headgaskets went and swapped engine instead, and made good power.
Not sure why, just one of those things.
09 December 2010, 11:58 PM
#19
Don't forget that he's still running the panel filter - so prob wouldn't make much past 350? So that'd be a potential bottleneck.
Or is the New Age OEM airbox setup much freer breathing, and therefore not a problem?
Or is the New Age OEM airbox setup much freer breathing, and therefore not a problem?
Last edited by joz8968; 09 December 2010 at 11:59 PM.
10 December 2010, 05:27 PM
#26
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LOL @ all of this, did people miss the part where he said it was not taking the timing needed to give decent results?
All i have seen is "ooooo check yer dustcaps they might be leaking" nonsense
All i have seen is "ooooo check yer dustcaps they might be leaking" nonsense
10 December 2010, 07:28 PM
#27
Micky: Spot on mate. Amazing how many people have a view but either can't read or are too lazy to read the thread but still have to have their 2p worth.
Simon has already told me the problems are not related to my turbo which holds boost nor my headers and I understand Paul accepts this from my last conversation with him.
I have made an offer to Paul to resolve the issues with his car or at the very least accurately identify the cause of the lack of power and if I fail to do either make no charge. I am always up for a challenge and await information requested from Paul and his feedback.
Simon has already told me the problems are not related to my turbo which holds boost nor my headers and I understand Paul accepts this from my last conversation with him.
I have made an offer to Paul to resolve the issues with his car or at the very least accurately identify the cause of the lack of power and if I fail to do either make no charge. I am always up for a challenge and await information requested from Paul and his feedback.
10 December 2010, 11:33 PM
#29
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Heavy oily deposits wouldn't help, such as might be found on a worn high mileage engine...
Mine has crisp'd a couple of valves but still goes like stink.
A bit of "history" would help any attempt at diagnosis.
IMHO.
dunx
Mine has crisp'd a couple of valves but still goes like stink.
A bit of "history" would help any attempt at diagnosis.
IMHO.
dunx
11 December 2010, 08:32 AM
#30
There won't be any logging if my offer is taken up, just common sense, systematic thorough investigation working through the car logically, carefully and progressively. The fault is probably not obvious or it may be a series of faults as both Simon and Subaru4U have spent time on this vehicle and I understand that it was already low on power before the current round of mods.