Very Disappointing Dyno Results, Help!

[Wacky Dee]

Please bear with me as I tell the whole story from the beginning .. it's not very long I promise!

I bought a stock standard R34 GTT a few weeks back with 62,000 Kms on the clock. The car seemed in very good nick, albeit no performance mods. So the next day (so to speak) I got a turbo back exhaust from justjap (front/dump pipe, highflow cat and 3" catback) and noticed a smoother drive and the boost was coming on earlier too (around 2500 rpm instead of 3000) and I was a VERY happy chap... until...

I took the car for a timing belt change since most of the drive/psteering belts were very worn and/or cracked (and who's to know the car's odometer hasn't been messed around with so it may have already done 100k).

One the timing belt was changed, I came to pick up the car and on my way back home I immediately noticed that the car didn't feel as if it had as much 'oomph' when the boost kicks in as it did before .. (to this day I'm not sure if this is just all my imagination). So I asked around and someone suggested that a timing belt off by one tooth could explain the perceived loss of power.

So I thought I might as well take it for a dyno power run and see what I get at the rear wheels. I took it to Bel's Garage (very pleasant and helpful peeps) and after 2 runs we noticed the car was doing only 143rwkw. The tuner thought that's probably about right and I said it sounds a bit too low as I was told that a stocker should get 150-160rwk and a full turbo back exhaust should probably add another 15kw as well so I was hoping to see something like 175-180rwkw but instead what we got was 143.

So he spoke to his mechanic who came over with a timing light and reckon the timing was right but then he noticed that the ingition timing wasn't reset to the default 15deg, instead it was set to 5deg only. He said whoever changed the timing belt, rushed the job as the ignition timing should be at 15 atleast so he cranked it up to 17. Both the mechanci and the tuner at this point seemed confident that this explains the low power output and that we can expect a lot more on the next run ...

So they do another dyno run and lose boost at 6psi and everyone's scratching their heads ... the mechanic says he reckons the actuator must have got stuck when open. Turns out he was right .. the actuator was stuck open apparently because the aftermarket dump pipe from justjap wasn't fitted properly .. So he fixes the actuator and we do another dyno run.

And this time we don't lose boost and the car does 145rwkw (2kw increase only since fixing the ingition timing!!!) and everyone's scratching their heads again "should be a LOT more than 2kw increase" they reckon.

At this point it's already getting late so they can't do any further diagnostics and put it all back together. The mechanic tells me he has no idea why it's making 145rwkw only, even after fixing the ingition timing.

So here I am now .. totally deflated and disappointed. I guess I probably should have gone in with lower expectations than 180rwkw, but 145rwkw with after-market turbo back exhaust just doesn't seem right. What do you guys reckon? What else could it be ?

Could it be the coilpacks? Maybe one of them is dead ? Anything else that could explain the lacklustre performance ? I will post the dyno graph (final one) as soon as I figure out how to work this damn scanner.. Cheers

Edited May 19, 2008 by Delta Force

[Yo-Yo]

just confirming the only modification is the exhaust?

If said exhaust is x-force brand I'd look at that more closely.

I currently run a hi-flow x-force 3" cat and can only manage about 192 rwkw on a dyno run at 12 psi, stock turbo so boost trickles down to 10 psi through the rev range.

Mechanic reckons It's due to the x-force cat and I can crack the magic 200kw mark if I change to a decent cat, so doing this fairly soon to see if it makes a difference

Edited May 19, 2008 by Yo-Yo

[paulr33]

because he advanced the timing ,it could be detonating (stock smic etc) and the ecu is backing off the timing

i would recommend the base time be set again and put in the correct 15deg spot

then do a stock ecu reset and try again

use some good fuel too and see how you go

[Wacky Dee]

yep, turbo back exhaust (and 18" rims) - other than that it's a stock car. The dump/front pipe is JJR, the cat is a highflow xforce cat (JJ guy reckoned he uses the same one in his GTR that makes 300rwkw) and the catback is an HKS Silent.

Edited May 19, 2008 by Delta Force

[jenkies]

hey mate dont fret.... dynos are a tuning tool and many read happy(too high) your figure sounds about right to me... to put things in perspective i have an rb26dett 80,000 (legit) after having a ecu remap (power fc) cat back and twin pods i made 147 on 9 psi.... thats with a gtr engine and aftermarket computer...... what matters is that it feels solid and boosts nicely...e.g. no missing and runs correctly.

[Wacky Dee]

because he advanced the timing ,it could be detonating (stock smic etc) and the ecu is backing off the timing

i would recommend the base time be set again and put in the correct 15deg spot

then do a stock ecu reset and try again

use some good fuel too and see how you go

The mechanic was listening for detonations and he said it wasn't making any ... actually both him and the tuner were both surprised that there was no detonations/pinging at the 17-18deg setting, they said most skylines would do it at those settings. In the end he reset it back to 15.

I am getting an O2 sensor installed hopefully sometime this week and they'll reset the ecu, I'll see how I go after that. Oh and I've only been filling up bp ultimate since I got the car (3 or 4 tanks now) Cheers

[Baconer]

sounds about right, skylines aren't the 500hp beasts people seem to perceive them as and dynos are tuning tools, not 100% accurate power reading machines

My 33 (RB25, same engine as your 34) made 142.2kw with the same minimal mods as yours (turbo back exhaust). 150kw may have been the as new, fresh off the assembly power figure but over time it will lose a bit of power.

Edited May 19, 2008 by Baconer

[Wacky Dee]

Here's the dyno graph...

[jenkies]

looks very healthy to me

[Wacky Dee]

sounds about right, skylines aren't the 500hp beasts people seem to perceive them as and dynos are tuning tools, not 100% accurate power reading machines

My 33 (RB25, same engine as your 34) made 142.2kw with the same minimal mods as yours (turbo back exhaust). 150kw may have been the as new, fresh off the assembly power figure but over time it will lose a bit of power.

See the thing is i wasn't expecting a beast but everything I've read before on SAU points to the 160-170rwkw figure for a stocker and additional 10-15kw with a turbo back. Are all those people just full of shit ? If so, why do so many make that much with the same mods and have it in their signatures?? Different dyno ??

Oh and another thing .. the tuner quickly looked up their database of previous customers and found another STOCK r34 GTT that put out 184rwkw. This was when he said 'hmm.. you're right' and called the mechanic to take a look.

I'm not trying to achieve the impossible but to me it seems 25% less power than a lot of other people with the same setup points to something not being quite right. Couple that together with the fact that I am pretty sure the car had a lot more 'oomph' before the timing belt change ..

Edited May 19, 2008 by Delta Force

[The Mafia]

lol at 180rwkw - 200rwkw on the factory ECU and stock turbo...

150rwkw is about the most you'll get with a factory ECU until you get something you can tweak

[monga]

208kw stock at the motor is around 200-210rwhp, with is around 140-150od rwkw on a new motor. Seems reasonable to me, depending on the dyno ect

[The Dan]

145rwkw is low but still correct for exhaust only mod.

They are 145rwkw stock but if you allow a small variance for dyno accuracy then you could be making 150-155

Most of the 34's I have done make 180-190rwkw after boost increase to 12psi, full exhaust and a remap on the factory ECU.

[Wacky Dee]

Hm ok I just quickly searched for dyno results and found this r34 gtt auto (8psi boost) and he made almost 20rwkw more than my car and with the same mods .. just a different dyno?

What's this about remapping stock ecu .. i thought you needed a pfc to remap/tune the ecu?? please do tell me more!

I might take it to CRD for another dyno run as I heard they use a different brand ..just to see if I get similar results

Edited May 19, 2008 by Delta Force

[R33Turbo]

I don't understand why everyones saying 145 seems like a reasonable dyno output for GTT R34, surely dyno is not an accurate tool to measure the cars power output but it must be pretty close to the kw its supposed to pull.

To be honest, the power ur pulling 145kwrw is bloody low cuz from my research and knowledge:

R33 GTS-T = 130-140 kwrw @ stock

R34 GTT = 150-160 kwrw@ stock

The results are for manual cars so if yours (Deltaforce) ain't manual that may be the partial reason why its low.

So you cannot compare the R33 RB25 with R34 RB25 Neo ok? its not supposed to make the same power. With an exhaust it could possibly push it up atleast 10kw without tune.

My recommendation for you is to go to a different mechanic shop to dyno run and compare the results if it makes any difference cuz if it doesn't and still stays around the 145kw mark, then definitely something is wrong.

Edited May 19, 2008 by R33Turbo

[R33Turbo]

lol at 180rwkw - 200rwkw on the factory ECU and stock turbo...

150rwkw is about the most you'll get with a factory ECU until you get something you can tweak

So why am i getting 184kwrw with just cat back and 11psi boost? (stock turbo, stock ECU)

Maybe my dyno run was just inaccurate and is showing 34kw more than its supposed to.

[Wacky Dee]

I don't understand why everyones saying 145 seems like a reasonable dyno output for GTT R34, surely dyno is not an accurate tool to measure the cars power output but it must be pretty close to the kw its supposed to pull.

To be honest, the power ur pulling 145kwrw is bloody low cuz from my research and knowledge:

R33 GTS-T = 130-140 kwrw @ stock

R34 GTT = 150-160 kwrw@ stock

The results are for manual cars so if yours (Deltaforce) ain't manual that may be the partial reason why its low.

So you cannot compare the R33 RB25 with R34 RB25 Neo ok? its not supposed to make the same power. With an exhaust it could possibly push it up atleast 10kw without tune.

My recommendation for you is to go to a different mechanic shop to dyno run and compare the results if it makes any difference cuz if it doesn't and still stays around the 145kw mark, then definitely something is wrong.

Finally someone with proof to back up what I was saying all along .. thanks mate! Got a couple of q's for ya if you don't mind .. did you have your ecu remapped by any chance and if so by who? Any chance you did a dyno run before upping the boost to 11 ? Where'd you go for your dyno run? Cheers

Edit: yep it's a manual.

Edited May 19, 2008 by Delta Force

[R33Turbo]

I never touched the ECU part of my car, i haven't remaped or used piggybacks so its still stock.

And yeah i did do a dyno run before boosting it to 11psi and made 161kwrw (bear in mind everything was stock including the exhaust). I dynoed it at Unique Auto Sports.

Edited May 19, 2008 by R33Turbo

[Wacky Dee]

I never touched the ECU part of my car, i haven't remaped or used piggybacks so its still stock.

And yeah i did do a dyno run before boosting it to 11psi and made 161kwrw (bear in mind everything was stock including the exhaust). I dynoed it at Unique Auto Sports.

Cheers mate, I'll try and get a dyno run at UAS asap and will report on the results.

[R31Nismoid]

The mechanic was listening for detonations and he said it wasn't making any ... actually both him and the tuner were both surprised that there was no detonations/pinging at the 17-18deg setting, they said most skylines would do it at those settings. In the end he reset it back to 15.

I am getting an O2 sensor installed hopefully sometime this week and they'll reset the ecu, I'll see how I go after that. Oh and I've only been filling up bp ultimate since I got the car (3 or 4 tanks now) Cheers

O2 has no effect on power

Also that dyno graph - useless without the AFR plots.