Author Topic: Down on power....  (Read 22958 times)

Offline RedRobin

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Down on power....
« on: October 31, 2008, 11:39:10 PM »
....

Going on JKM's Dyno-Dynamics rollers when my Revo Stage1 was installed, plotted smooth healthy curves with 236 bhp and just under 300 ft lbs. In late September Revo HQ loaded Stage2 and we went out on the road and everything was fine and dandy - A subtle but strong power. So, in early October about 20 of us met up for a social rolling road session at JKM and I was very surprised to plot less than 230 bhp with Stage2.

My VW dealer had spotted that my Milltek cat was deteriorating and so Milltek kindly replaced the whole downpipe and sportscat but a diagnostic session on JKM's dyno still showed only 228 bhp. Keith at JKM thought it was likely to be a boost leak because of data logging the boost request levels.

So today we had another session and Jim took the car apart as follows : -

Oil blow by leak on seals by Turbo Discharge to Intercooler. Inlet seals removed and cleaned and all ok in that area now.

Forge DV removed and checked. Seals renewed anyway and no faults found.

DV vacuum lines checked with vacuum gauge and all ok.

PCV valve checked and all ok. PCV valve blank-off used for testing - No differences to performance/boost response.

Air box removed and car run - No changes to performance/boost response.

As there are no apparent boost leaks at this stage JKM would like to mechanically inspect the turbocharger for any internal damage or potential cracks on wastegate housing etc. They are fairly confident it's the turbo but of course can't be 100% sure yet.

So, my options are : -

1) -  Inspect the turbo but have to hire a car while it's either sent away to a specialist if no damage is obvious. This would have a cost and would also probably not be financially viable to repair. 

2) - Buy a new K03 turbo (about £650) with 2-year warranty. BUT....That warranty would be ineffective because VW would claim that my car is too modified by its remap and exhaust.

3) - Buy a hardly used K03 which has done less than 4,000 miles and which JKM know to be in top notch condition. It was taken off for a K04 conversion. Cost £400. Swop turbo's in the same day.

4) - Spend several thousand pounds (£4K) on the K04 conversion and end up with around 300 bhp but all the potential problems that could bring to a stock GTI engine internals (not Ed30).

So I'm going for option #3 and I bet lots of you will say go for option #4 the K04 conversion!!

Meanwhile, I'm running around in stock map and it does feel rather dull by comparison, though of course it's not!

Initially it's easy to think that none of this would have happened if I hadn't modded my car, but as she's only down on the power she should be (closer to 260 bhp instead of today's 236 bhp), without being modded and going on the rollers etc, I might not even suspect anything was wrong and the situation become worse.

Apart from the obvious benefit of the quasi-religious experience of driving a fast modified car, I am convinced that running a modded car responsibly encourages far better care and maintenance.
« Last Edit: November 01, 2008, 12:22:40 AM by RedRobin »


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Offline Top Cat

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Re: Down on power....
« Reply #1 on: October 31, 2008, 11:50:54 PM »
Thats not good news Red.  :sad: I would have a good think about how long your going to keep the car for i say this only in relation to the fact if you go for the KO3 but then get drawn into going for the KO4 at a later date you no you cant resist and if you keep the car for any length of time you will be pinning for the bigger turbo at some stage. plus i thought the K04 worked well with our engines and produce more torque due to better compression. either way its not good it goes with the territory i suppose.  :smiley:

Offline vRStu

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Re: Down on power....
« Reply #2 on: October 31, 2008, 11:59:19 PM »
Bit of a blow that Robin.

When have you got her booked in for then?
Stu...

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Offline RedRobin

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Re: Down on power....
« Reply #3 on: November 01, 2008, 12:21:27 AM »
....

Not booked in until Kate knows when JKM can get that 4k miles K03 from its owner.

JKM's basic K04 conversion (taking into account my existing mods) would be £4,000 incl vat and that doesn't match what I want - I actually don't want 300 neddies at my front wheels, even though I have a Quaife. I don't want the insurance hike either. I prefer my power lower down in the more legal speed range - I don't drive the German autobahns that often.

But isn't the Ed30 engine stronger and different from the GTI? Or doesn't it matter regarding a larger turbocharger?
 
:happy2:

« Last Edit: November 01, 2008, 12:24:15 AM by RedRobin »


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Offline Top Cat

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Re: Down on power....
« Reply #4 on: November 01, 2008, 12:24:31 AM »
yes the ED30 does have stronger internals but the compression is better on ours. i believe.

Offline RedRobin

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Re: Down on power....
« Reply #5 on: November 01, 2008, 12:25:34 AM »
....

But why is higher compression better?


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Offline Top Cat

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Re: Down on power....
« Reply #6 on: November 01, 2008, 12:32:04 AM »
TT will have to answer that one all i can remember is on a recent rolling road a standard gti engine out performed the ed 30 engine on torque or had a flatter curve than the ed 30 engine when they both had the same K04.
At the end of the day though Red its getting them on the floor in my opinion 250 BHP is about the limit for front wheel drive motors.

Offline RedRobin

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Re: Down on power....
« Reply #7 on: November 01, 2008, 12:36:57 AM »
....

That's exactly what I think - Driveability, getting the power down without traction issues and eating tyres.

I must go to bed - Gotta get up early to get to Weston's dyno session......... :happy2:


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Offline WhiteGTI

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Re: Down on power....
« Reply #8 on: November 01, 2008, 08:14:32 AM »
Now your making me nervous with my Stage 2 !!!!
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Offline vRStu

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Re: Down on power....
« Reply #9 on: November 01, 2008, 08:39:43 AM »
In fairness the TFSi turbo's have been pretty reliable especially when compared to the TDi counterparts.

I think, assuming it emerges that this is the problem, this would be the first case I have heard of.
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Offline Teutonic_Tamer

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Re: Down on power....
« Reply #10 on: November 01, 2008, 09:44:55 AM »
Robin, have you ever been on any other rollers?  Maybe JKM have had theirs recalibrated since your first run way back when.  I am aware that DD rollers are supposed to be the most tightly regulated, by the manufacturer - and if JKMs were being "over generous" when initially installed - a subsequent recalibration might have down-corrected their readings.  I simply mention this because you seem to be saying that the stage 2 "seems better" - so your butt-dyno is telling you the stage 2 is better, but the RR is telling you the opposite.

Engine oil - what brand, type and spec oil do you use?  And what is your oil consumption like?  Do you religiously keep it topped up to the max by adding small amounts frequently, or do you let the oil get fairly low and then add quite a lot?

Onto the specifics of oil in the turbo discharge pipe.  Firstly, you stated "Inlet seals removed and cleaned and all ok in that area now" - but do you mean the seals on the pipework, the seals on the turbine shaft, or do you mean the valve stem oil seals for the "poppet valves" in the cylinder head?

Regarding actually finding oil in the turbo discharge pipe, I think this is fairly common.  I found oil in mine, and inside the standard intercooler - but it wasnt much.  Maybe one or two tablespoons, which is fairly reasonable.  However, I wonder if the stock GTI intercooler has something to do with this?  I personally reckon the stock i/c is slightly restrictive, which can cause a slight backpressure on the inlet side of the turbo.  Since upgrading mine to the S3 cooler and twintercooler, I do notice a much more rapid rise in turbo boost - which prooves that the airflow through the inlet tract is much freer and less restrictive.  Maybe this is also having an effect on the way that the oil vapours from the crankcase ventilation system are not getting to the combustion chambers quick enough.  Think of having a hot shower in a closed bathroom - the shower will steam away, but if you have a mega powerful extractor fan immediately above the shower head, it will suck out all the steam.  However, if you have a clogged, weedy fan, the steam wont get sucked out, but will condense on your bathroom mirror, and then dribble off the bottom edge.

Onto a couple of other issues.  Did JKM plug in a VAG-COM to check for fault codes?  And did they carefully monitor the N75 cycle?

Regarding the actual replacement of the turbo - only you can decide which is the best way.  However, I would personally never recommend any second hand turbo, no matter how well the previous owner claimed to have looked after it.  You only need to recall some of the threads on the other GTI fourm (revving engines whilst stationary, "blipping" throttles, correct turbo cool down - I even think that you mis-understood about the cool-down procedure), and it simply showed a fundamental lack of knowledge on how to car for an engine in general, let alone the specific requirements of a turbo.  If I were forced to only take a 2nd hand turbo, then I would send it to a specialist turbo re-builder for a complete overhall and warranty.

If your original turbo is knackered, I would personally seek a specialist recon, or go for the genuine new VW part.  Yes, I understand your POV that the official VW 2 year warranty will probably be void - but it is the "peace of mind" from getting an OEM supplied part - you can pretty much expect an OEM new turbo to last a long while, but how long will a slightly cheaper second hand one last.  The labour charges will be the same, but if the 2nd hand one doesn't last, then someone will be paying the labour charges all over again.
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Offline Teutonic_Tamer

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Re: Down on power....
« Reply #11 on: November 01, 2008, 09:51:27 AM »
yes the ED30 does have stronger internals but the compression is better on ours. i believe.

No, no, no, NOOOOO.  :scared:  :party:  :nerd:  :P  :sad:  :fighting:

The Edition 30 engine does NOT have stronger internals.  It has different internals, and only some.  The durability of the Ed30 engine is exactly the same as the standard GTI engine.

Only the Audi S3 engine has stronger, reinforced internals, along with a stronger cylinder block/crankcase.  :rolleye:

Yes, compression ratios are different, but that is for a specific reason, and nowt to do with any durability allowances.
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Offline Teutonic_Tamer

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Re: Down on power....
« Reply #12 on: November 01, 2008, 10:00:45 AM »
....

But why is higher compression better?

The compression on the standard GTI is higher than the Ed30, and the simple reason is down to peak pressures in the combustion chamber - which will be nigh-on identical in both engines.

The reason the standard engine has a higher compression is because the turbo is smaller.  Smaller turbos simply mean better "low-down" power.  But the small turbo tends to make the engine run out of steam at higher revs - due to the fact that smaller turbos can flow a smaller volume of air - so the higher compression ratio compensates.

The Ed30 engine has a lower compression ratio, simply as a reverse reason over the standard engine.  The Ed30 has larger turbo.  This can flow a larger volume of air at higher revs, hence the lower compression is required as a kind of "safety net".  You could argue that VW should have kept the higher compression ratio of the standard GTI engine, and simply lowered the turbo boost - however, they know very well of a very simple word - "remap".  High turbo boost + big turbo + high compression ratio = much shorter engine life.
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Offline T88OMM

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Re: Down on power....
« Reply #13 on: November 01, 2008, 11:10:49 AM »
KO4 KO4 KO4  :mad: :jumpmove: That would be my decision but then again I can never get enough POWER!  :jumping: The second hand KO3 sounds like a viable option and a relatively inexpensive one at the same time. As you say you dont want 300 neddies going through your front wheels so this has gotta be the route to go down!  :happy2:
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Offline RedRobin

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Re: Down on power....
« Reply #14 on: November 01, 2008, 07:49:34 PM »
Now your making me nervous with my Stage 2 !!!!

....I'm very confident it isn't down to Revo Stage2. Boost is set at 7, which isn't at all excessive. Also there are plenty people running Revo's Stage2 on the 2.0T FSI with very similar mods to mine (you for example!).

The boost graph shows that it's spiking at 1.2 bar and then dropping off badly from 2,400 revs.


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