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[Andy89]

Ran my omega on a dyno today on the Wheel hubs

Got 195,5 hp @6300 and 254,6 nm @3598

Noticed that it fell at 4300, is there any way to improve this fall? (I'm porting a reconditioned engine, witch i will put in by spring, and then take a dyno run again)
Is there anything i can do to that engine to improve the curve?

Anyone here who has had a dyno run on their omega?

[albitz]

Very respectable figures for a 15 year old car.Not many ponies escaped from your paddock over the years.

[feeutfo]

Hmmm, wonder if there's a multi ram issue?

[Andy89]

Very respectable figures for a 15 year old car.Not many ponies escaped from your paddock over the years.

I may have put some extra horses back in the stable 
(The engine itself has low compression on one cylinder, it uses oil and it throws up much oil into the inlet if i'm sideways driving) witch is why i have a reconditioned engine im working on
But the engine has been chipped, fitted headers, removed the cats and fitted 4 bar fuel pressure

Hmmm, wonder if there's a multi ram issue?

I'm not sure, but it looses power at 4300 rpm and shoots off at 4500

[Kevin Wood]

I'd try it again with the original fuel pressure regulator. It might well be bogging down due to running rich. In fact, did they monitor the AFR during the dyno run?

[feeutfo]

Ah, so if it's been fiddled with, it'll need sorting to the new set up/headers etc.

Proper set up session on the Dyno then. Run it up, check the data, adjust, and do on until happy

A good Dyno man can often tell an issue just looking at the graph, ime.

[TheBoy]

I've seen chips that seem to bog down, then take off.

I'd shove the std FPR on, as Kevin Wood suggests, a higher pressure in the fuel rail won't improve performance on the Omega, as the injectors are pretty free flowing.  All what happens is the engine trims back the injection duration, following feedback from the lamdas, so any performance boost you feel when fitting is very short lived.

When you change it back, if you have the facilities, reset the trims.

[Andy89]

It was worse before the tuning, it's been this way since i bought it. (straight after i fitted the headers, the boost at 4500 disappeared, and felt like a good pull all the way, don't know if i did something, or the ecu did something, but the boost is back)
Don't you guys feel a boost in power at 4500? (x30xe that is)

[TheBoy]

It was worse before the tuning, it's been this way since i bought it. (straight after i fitted the headers, the boost at 4500 disappeared, and felt like a good pull all the way, don't know if i did something, or the ecu did something, but the boost is back)
Don't you guys feel a boost in power at 4500? (x30xe that is)

Check the operation of both multirams, esp if the lag was there with the standard map. In fact, might be worth slapping in the original map for testing, as that should give a pretty flat torque curve.

All chipped Omegas seem to have a burst of power in the top couple of k or rpm.

[Andy89]

I have had 2 engines, so that means everything was changed once, i have even testet a new ECU (this was not done because of the lag)
I have seen that the multirams are working.

But the lag was worse before my tuning (atleast it feels like it)

So what you are telling me is that you don't have sudden boost in power at around 4500?

[feeutfo]

Your description, prior to fiddling "sounds" like a multiram issue ime.

Further than that check cam timing..? Was it done with locking kit to the gauge marks etc.

[Andy89]

A bit odd if both engines would have wrong timing.

Here is the graph, the upper line (yellow numbers) is with the lights and fan turned off, the lower line (green numbers) are with lights and fan on.

[Kevin Wood]

Without seeing the AFR it's difficult to say what that dip is. ISTR that the standard plots for the engine had a similar shaped curve, with a bit of a dip around there, but that must be quite noticeable on the road.

Looking at the curves, you can see a smaller dip at around 2600, and another at 3300. These are probably resonances in the intake and exhaust system, and it makes me wonder if the one at 4500 is a particularly bad example of this. Perhaps a combination of intake and exhaust resonance.  The spacing almost fits.

It might be possible to tune some of this out with a mappable ECU or tweaking the cam timing, but then again, it may be that the intake / exhaust system has a length that's not working well at that speed. Often you've got to put up with this sort of issue on a tuned engine, but given that it's not running more than standard power, I'd be inclined to put it back to the standard setup and see what happens, as something you've changed has made matters worse IMHO.

[Kevin Wood]

It's also interesting to see how much difference loading the alternator has made, especially at high RPM. Guessing it's really inefficient at high speeds, or that engine was still hot from the previous run and didn't quite make as much power.

[2woody]

I'd say there is something not working in the multiram department there.

They do have a "take-off" at 4500 rpm, but it's only really noticeable if you go looking for it. It's so small that it isn't really there if you don't.

the exhaust manifolds could cost you something if they're poorly designed. The standard ones are non-interference, which means that they're specifically designed not to give any shock-wave tuning at all. After-market manifolds could give some tuning at some revs, but equally less at others.

What about WOT lambda ? could your high-rev performance be due to lambda inactivity, whilst the low-rev performance is hampered by the fuel pressure regulator - I think we all agree that that's a dreadful idea and should be thrown over the nearest hedge.