Dyno results in motec 6.9

[motec6.9]

Hi guys after to much time and money my 6.9 is now running and tuned i have the email from David at trg with the dyno results. I come home on the weekend so i will pick it up and take it to the paintshop at the start of the nextweek. after spending close to $4000 on exhaust and custom extractors fitting a $3500 motec m48pro computer another $7000 to fit and tune with fuel rails and injectors i must say i am disappointed last time the car was on the dyno it had a burnt exhaust valve and was down on compression on 2 cylinders and made 164kw at the rear wheels new workshop healthy motor good compression it made wait for it 218.9 hp at the rear wheels or 163.5kw  but this is the interesting part which will be seen when i get around to posting dyno result email it made that power over 1300rpm apparently the motor ran out of airflow due to the 75mm throttle body as dyno tune was done with standard throttle body due to me wanting to have it running i need to look at modifying intake and throttle body then seeing what happens apparently when a motor has that kind off flat responce it means there is a restriction somewhere so we wait and watch with interest

[TJ 450]

Wow, that's dissapointing. Are you sure there not a basic issue with valve timing etc?

Also, just thinking about it, there could be a considerable loss in the transmission and the rest of the driveline too.

Tim

[13B]

Check your timing chain for stretch and renew / adjust with offset keys as needed.

I.

[motec6.9]

hi guys i have spoken to David and he assures me that all specs on the motor have checked out to be with in specs as stated else where goldie 2 had reciets for a top end rebuild 5000km before a landcruiser hit it from behind and compresion is between 148 to 145 psi in all cylinders after freeing up the exhaust side and having greater control with fuel and ignition if nothing else i will have better fuel consumption figures as when it was last on the road after fitting motec fuel usage went down by 2ltr every 100km so that is a plus i will investergate fixing airflow problem as that is what the dyno is saying with a flat power curve there is a restriction somewhere if it was free flowing and getting all the air that the motor required it would build to a peak power output before dropping away but it holds the power curve for 1300 rpm so i will try to fix then hit dyno once more

[oscar]

Geez, there's a supercharged 280 on youtube that does 217rwhp with just an m90 bolted in.  That is disappointing motec I hope it is just an airflow issue.  I suppose it makes sense that none of those enhancements are going to make much difference if the air's not getting in but with custom extractors alone I would've expected an increase at least.  Other than bolting on a larger throttle body I wonder what else is possible.  I'm thinking custom twin log plenums similar to the 6.3 but with a throttle body for each side.

You wouldn't have seen this one motec but check this 450 for inspiration  http://forum.w116.org/test-drive/305hp-450se-0-100kmhr-in-5-4s/

[TJ 450]

Perhaps it has to do with the free flowing extractors/exhaust upsetting the system...

Anyhow, I'll be interested in the upcoming developments.

Tim

[motec6.9]

Hi oscar i have spoken on the phone to David and he tells me there is nothing wrong with the motor so when i see him on monday i will try to figure out how to find my missing stable from what i have been told it gets to 218hp and stays there for just under 1300rpm changing fuel tables and maps does not make any difference to power output so David is suggesting but i will know when i see him that the engine is running out of airflow

[motec6.9]

Hi TJ i dont think so but will investigate why and how when i speak to David on monday but i am determined to make a lot more power than what i have at the moment i need to find out were the problem is before good motor goes back into car later this year when finished on a briter note since the car was started it has not dropped in the suspension not bad for a car that has not moved in 5 years

[TJ 450]

Sounds good, motec6.9.

What I should have said, was that because the intake isn't able to keep up with the exhaust, it might be fair to assume that the engine would be down on power from stock. Just a thought anyway.

Maybe you need a custom intake manifold, but I'm sure you'll get it sorted either way.

Tim

[motec6.9]

Looking forward to seeing car on Monday and hearing slight problem off 106db exhaust noise but will fix that some how and looking into sorting tune so car can develope what it should be able to make should have repo aMg front spoiler arriving sometime this week will take photos and send to you TJ

[koan]

motec, a bit concerned about 145-148 psi compression test, my best cylinder was 165 dry and 175 wet, that was before head rebuild (worst was 80/95). I would now expect 165/175 as a minimum on all. Engine is 8.0:1 compression.

koan

[TJ 450]

Koan, it sounds like you might have an exceptional example (actually, I knew that from seeing your engine porn in the gallery and drooling over the keyboard ). As an aside, I haven't forgotten about the suspension pump... it's going on the M116 380 which is being rebuilt over the next few months.

Here's a quote from an old post of mine regarding the first compression test I did on the 6.9. I would imagine that it has improved with driving though.

"I performed a compression test today... 150psi +-5%, although I'm not sure what the specified pressure is for an ADR compliant motor."

FWIW, My 450SEL was around 160-165psi before the heads were replaced... probably more of a "wet" reading due to oil from the previously worn valve guides and shot seals.

I think the 6.9 is due for another compression test for curiosity's sake.

Tim

[koan]

Koan, it sounds like you might have an exceptional example

Not sure about that. If you recall a discussion a while back about how to keep  rubbish from getting down between and cylinder wall when scraping carbon off the pistons I said I smeared grease around the bore and wound the piston up into it.

When I got the engine back together and fired it up for the first time it sounded really good, a very strong and tight sounding idle. Hard to describe exactly what was different, it just sounded good, the grease in the bores was obviously creating a tight seal.

But after ten minutes of very smokey running as the grease burnt off it went back to the soft, soggy idle it had before.

I've wondered if a new set of rings would permanently restore the strong idle.

I should do a compression test with the rebuilt heads for future reference.

koan

[SELfor50]

motec, a bit concerned about 145-148 psi compression test, my best cylinder was 165 dry and 175 wet, that was before head rebuild (worst was 80/95). I would now expect 165/175 as a minimum on all. Engine is 8.0:1 compression.

koan

Very interesting.  We did a comp test on the NOS engine when installed, but it was before actually running the engine.  Just once we connected everything and had crank.  And it was bang on 150psi on every single cylinder.  The test tool was just one of the ones you push / hold in the plug socket (eg just rubber end)..  But it was identicle on all cylinders.  Maybe I'll get a different reading after running it in now (it actually feels like it's loosened up a bit and is a little more free revving).  I think it's time for another test for me too.


That sucks Motec, but I'm sure you got enough in the pipeline to sort the issue or find away to get a heap more HP.

TJ's comment about the extractors etc and manifold not keeping up sounds pretty pheasable too. 

[koan]

No reason to think this but my compression tester might be a bit optimistic with the readings.

koan