[Mk2] [Turbo] Confused. Can someone 'in the know' take a look at these figures?

[FreeFall]

Hey peeps,

I'm after some comments/advice/ideas on a mystery I have. It seems that by trying to get more power I usually end up with less! Here is my story, I hope you have the time to read it all and perhaps have some ideas on the way forward, 'cos it's baffling me...

When I first bought the car it had a 2.2 HKS stroker built by TDi in Essex but not many supporting mods (save for a small HKS GT turbo). So, my plan was to uprate the necessary to get the best possible out of this build, which cost the previous owner a fair whack of cash.

Here's my original thread way back in 2005, making:

245 bhp hubs @ 6500 RPM
221 lb-ft @ 5500 RPM

http://www.imoc.co.uk/forums/viewtopic.php?t=25741


So, then the plan was hatched and it went to 3S for the following mods:

T-67 kit
Radtech CC
Rogue Fans
850 injectors
Dual-feed rail
AFPR
Walbro pump

Then it went to Owen Developments for fitting and mapping of the Motec M4 and removal of the AFM. It was mapped on a very hot day in the summer (about 36 degrees centigrade IIRC) and pushed out:

395.9 bhp fly @ 6887
316.3 lb-ft @ 6005
1.5 Bar boost



So, I was quite happy with that. I figured it wouldn't take much to up the boost a little and tweak the map (Owens were in a hurry to get it finished as I needed the car for TOTB 2006) - then I would be at my goal of 450 BHP at the fly.

Time moved on, I had various small issues with the car and it again went to 3S to have these sorted and to get some gauges fitted so I could keep an eye on things. Ryan at 2-bar Tuning had to tweak the map to get it through emissions and richen it up at the top end as it was running very lean. I then thought I would go back to my old friends at TDi and get the boost turned up and mapped accordingly. I was however a little disappointed with the results:

322.6 bhp Hubs @ 6850
294.1 lb-ft @ 4710
1.7 Bar boost peak, tailing off to 1.3 Bar at 7000 rpm





It was thought at the time that the wastegate spring was not strong enough but I later found that the HKS EVC was plumbed in incorrectly. At this point I took some advice from a member on here and replaced the EVC with a simple 2-port valve and also installed a 4-bar MAP sensor. Dave Rowe from Motec UK then mapped it on the road to 1.9 bar (which was showing on the HKS EVC that I had left connected just to monitor boost). It felt a lot smoother in the power delivery, but slower - I then hooked up with the eight-six.co.uk crowd last weekend and the power was down again, boost peaked at 1.7 bar. I also had them graph the boost and AFR:

262.4 bhp wheels @ 6440
307 lb-ft @ 4647
Boost building to 24.4 psi (1.68 bar) by 6500 rpm












So, there is my dilemma. The most puzzling thing for me is why the peak torque has dropped from 316 @ 6005 to 307 @ 4647 - why does the peak come in so much lower in rpm? A couple of comments received so far suggest that the cam timing is out. I'm not really sure what this means so any pointers there are welcome (it has HKS 264 cams I believe).

I never wanted to 'chase figures' and am off to Santa Pod this weekend to see what the ar$e-dyno says. Just a bit confused as to why the different results (I know comparing wheel/hub/fly is not an exact science and that dynos differ). I'm just a bit miffed that throwing more cash at this (and upping the boost) seems to come up with worse results!

If you've read this far and studied the graphs then thanks! You might know what's going on here. If not, thanks for looking anyway

Nick

[FreeFall]

Sorry, meant to put this in 'Modifications'. Could a kindly mod please move it?

Thanks,
Nick

[AdDaMan]

it doesnt help that you have been to several different rolling roads and different tuners.

[RichardPON]

Different rolling roads with different operators will give wildly different figures.

The comparison is, unfortunately, absolutely worthless.

[Caribbean_Blue]

Moved to Mods as requested.

[FreeFall]

Thanks for the replies guys. I think this runs a little deeper than just different tuners/dynos as I can't see the figures being that much different - i.e. a loss of almost 100 bhp and the torque peak moving from 6000 to 4600 rpm.

I have a couple of things to try, will keep you posted on the outcome.

[Andy F]

Hi Nick, what a bummer!!
It does sound like the cams are out..
If you can take a log from the motec and look at the advance table
if the advance is getting less and less as the revs go higher, the cams
will be out.
Have you rung Dave to see what he thinks?

[Harry]

Hope you get It sorted Nick. Sounds like Andy might have found It.

[FreeFall]

Went back to the RR today and still no joy. I replaced dist. cap, leads, rotor and plugs yesterday - did an oil/filter change at the same time. Drives smoother on the road but still down on power.

Patrick @ Rogue suggested that the exhaust baffles might have collapsed, resulting in back pressure, so we did a run with the end cans off - no difference except the torque peak shifted a little and picked up very slightly.

The RR guy then advanced the timing (via the distributor) about 5 degrees, ran a lot worse.

The AFR was very rich still - less than 10:1 at some points. he turned down the fuel pressure from 38 psi to 30 psi and while the AFR improved to around 10.8:1 the power was the same.

Then, on the way home, a weird thing happened. I was cruising along at 60 mph in 5th when the car just cut out. There were no dash lights or hesitation - it just seemed to coast for about 3 seconds with no power (the rev gauge was showing zero) and then came back to life I don't recall if any other electrics were down at the time as I was looking for somewhere to pull over. It did this twice the other day as well, before I had changed all the ignition components. Could it be something as simple as an earth? Any ideas of anything else that could cause this that might be linked to the power drop?

Turbo is performing OK with 11.7 psi by 3500 rpm and 24.4 psi by 6500 rpm.

At this rate I may as well break the engine for all the goodies and stick a stock lump in there - I'd be getting about the same power and using a lot less fuel!

I'm stumped. Time to take it to a specialist and throw more money in the pit I guess

Nick

[FreeFall]

It does sound like the cams are out..
If you can take a log from the motec and look at the advance table
if the advance is getting less and less as the revs go higher, the cams
will be out.

Sorry mate - forgot about this. Is this what you mean? Here is the map for the top end of the rev range.

[Harry]

No! this Is bull$h1t now! Your MR should be putting out much larger power! Stevo-O spitelli's Is about your spec. and at about the same boost Is putting out heaps.What exhaust and manifold are you using Nick? Do not give up yet!

[Marf]

Is the engine down on compression? That could explain the power loss.

[Harry]

One would have thought a leak and compression test would have been looked at upfront a good call too!

[FreeFall]

No! this Is bull$h1t now! Your MR should be putting out much larger power! Stevo-O spitelli's Is about your spec. and at about the same boost Is putting out heaps.What exhaust and manifold are you using Nick? Do not give up yet!

Cheers Harry - manifold is a SS jobbie that came with the T-67 kit I got from GTSChris (so a GReddy maybe? ). The exhaust is the HKS Super Drager that we spoke about recently.

Is the engine down on compression? That could explain the power loss.

Hi mate, I did a compression test a couple of months ago as I was getting oil in the intake pipe. Results were 175/172/175/175 [ http://www.imoc.co.uk/forums/viewtopic.php?t=91349 ]. Always worth another test this weekend I guess. I changed the oil yesterday, there is no mayo anywhere and the oil looked good.

Nick

[Marf]

sounds like compression wont be the issue then

[Harry]

Steve also has the HKS exhaust and flows very well with large power. No harm fitting a single exit say Border or say Apexi GT just to see? I am probably going to be fitting my HKS superdrager back on once the new flexi Is fitted. The 5Zigen Border Fireball exaust Is the one Chris Improved with 3.25" front pipe and the same massive flexi.Incidentally this exhaust flows more than his current Apexi GT and lost boost plus power on the GT! Sorry Chris!

[Steve Horrocks]

May be out, but are you still using the Rogue/Radtec CC? Wasn't there a flow issue when used over 1.4/1.5 bar or was that a different one?
Is your spec still as per your garage?

Interested as there aint many of us T67 users about! lol

[Harry]

Steve also has the Radtec and T67 Greddy If memory serves and gets around the 450-500 power mark at 1.7 bar. Incidentally he has Mark's previous:-Nightspirit engine fully sorted It Is smooth as silk and tight pulls beautifully. http://s267.photobucket.com/albums/ii30 ... 9cba09.pbr

[FreeFall]

May be out, but are you still using the Rogue/Radtec CC? Wasn't there a flow issue when used over 1.4/1.5 bar or was that a different one?
Is your spec still as per your garage?

Interested as there aint many of us T67 users about! lol

Hmm... I was wondering whether I should take off the turbo -> CC pipe and see if there is any oil in there which might suggest that the core is contaminated, as I do get some oil in the intake pipe [ see http://www.imoc.co.uk/forums/viewtopic.php?t=91349 ] - but then I got to thinking that if the boost is around 25 psi measured at the intake manifold then there is no restriction there .

I'm still baffled as to why the car cuts out every now and again (rarely). if I go for a drive and then switch off, it will also stall 3 or 4 times when I restart it sometimes, once I get it running and come off the throttle it's fine until I switch off and restart again. Probably a red herring though.

Nick

[FreeFall]

sounds like compression wont be the issue then

No but I appreciate your response. I've seen your recent posts and you should post more often!

Joined: 17 Jan 2006
Posts: 32

You lurker,

Nick