TimsLS1

At last after 9 months I have my M6 LS1 Commodore running, it was my first engine rebuild so I am pretty happy with myself, but wondering what now?
I don't like the way it drives I have to keep revs over 2000 rpm or it bucks, it's only a mild cam at 217/228 110 LSA. A few weeks ago I took my PCM to my tuner to make a few adjustments because I told him I want to run the new engine in for 500 miles before tuning on his dyno (had used him before with another cam of similar duration), but now Im not so sure I want to run it in before putting on dyno as it's next to impossible to drive in traffic despite idling very well. I have a stiff five puck ceramic clutch to make matters worse.
​​​​​​ Power curve is weird a lot of power between 3 and 4000 rpm is quite sudden and lots of backfiring on deceleration downchanging.
I did a scan with my torque pro play store app and have no fault codes.

Darth_V8r

iTrader: (4)

Dyno tune will not fix street tuning issues. Very likely need to spend time dialing in fuel and spark timing. That can can be made to drive very smooth.

Mavn

iTrader: (3)

You cammed an ls. Needs drivability tuning .

stockA4

Congrats on getting it going Tim! I'm sure you will find a tuner that will get it right!

TimsLS1

Thanks all
Darth_V8R I did not know dyno tune would not fix street drivability issues, my old cam was so smooth compaired to this one it was 219/224 on 113 LSA. I'm sure I'll ruin the drivetrain quick due to all the bucking if I drive it like it is in traffic. Might take it for a few runs on the freeway today.
Regards Tim

HappySalesman

iTrader: (3)

"Dyno tuning" at it's most basic is just WOT tuning. Driveability tuning takes a lot more work and time. Some good tuners can take care of driveability stuff pretty quickly based on their experience and knowledge, other it takes a lot of time (and unfortunately, money).

Is the car still running on a factory tune? Or did you have your tuner make adjustments based on your setup before you started driving it around, etc?

TimsLS1

The PCM had my old tune from previous dynoed cam done with with same tuner with near identical duration, so I asked him to look at same PCM he tuned for old cam for the new cam I'm running as I had also upgraded to LS2 injectors and he said it would flood if I tried to use it without allowing for that, so he made some adjustments to my PCM.

I booked the car in with him today to have it tuned properly on his dyno in a few weeks, until then I'll try and run it in a little, probably on the freeway as its hard to manage on the street with all the jerking.

New cam has significantly more overlap despite duration being near the same so I'm not surprised it needs a re tune just did not expect to be unable to sit at 1750 rpm in 3rd without bucking.

When it bucks I often take it out of gear stop and try and take off again reving it higher, that seems to work. If I let it continue with all the jerking it gets progressively worse, feels like the engine could rip my car in half if I let it.

HappySalesman

iTrader: (3)

So the only change you made was the camshaft and the new injectors? What were the specs of the old cam vs the new one?

TimsLS1

Yes that is the only change with exception of rebuilt engine mild porting on heads 10.5.1 comp 91 to 93 octane fuel

old was 219/224 113 LSA +3 .551 lift, = minus 4.5 overlap
new is 217/228 110 LSA +2 .590 lift, = plus 2.7 overlap

equals 7.2 more overlap despite less intake duration.

Part of my goal was to keep duration close to same and change all other parameters as bit of experiment to see what difference it made, but thinking about it perhaps too much has changed to get any sort of apples to apples comparison.
​​​​​​

Mickyinks

Id say dont drive it and let your tuner sort it out. If you have new injectors you dont want to have it pumping to much fuel in and wash the bores..
He can run it in on the dyno, then tune on dyno and he will also test drive and final tune for street .

TimsLS1

Thanks I would have thought at cruise the oil would be constantly replenished too quickly for that to be a problem but at idle that is another matter.

Mavn

iTrader: (3)

No. Just no . 😅

omc8

iTrader: (7)

Hey thats great you finally got your build done . Like to see results comparison of them too , my guess is the new can will come in earlier in torque and power have a broader curve and carry out longer up top too .. I know you guys express power in kw , but we will get the idea of changes have made . Cheers

TimsLS1

Thanks much appreciated,
Engineering Explained on youtube says not to idle to warm up modern cars before driving becuase it can wash the oil off the bores, he says just drive gently till its warmed up, I guess it could be washed off at any speed as with my case largely unturned.

Im running motorcycle oil in it to help run it in as it was the only non friction modified oil I could find locally that was correct 5w rating. Motorcycle oils are generally non friction modified as the wet clutch shares the same oil as the engine.

.boB

iTrader: (1)

When you installed the 5 puck clutch, did you also install a light weight aluminum flywheel? If so, that could be your problem.

Motorcycle oil? Never heard of that one.

When they say not to warm up the engine by idling, that means don't let it sit and idle for 15-20 minutes. Not good for most gas engines. Letting it idle 1-2 minutes after starting is actually good for every engine, gas and diesel. You're making sure all parts are getting oil, and getting some heat in the oil before driving.

TimsLS1

Thanks boB, no it's a 10 kg Chro Mo flywheel, I'm getting a lot more used to the 5 puck clutch and I don't feel the extra weight in it anymore.

After seeing this video I no longer warm up my engine idling for more than 10 seconds. Although today was an exception with my car untuned I have to keep it at 3000 rpm crusing on the highway in 4 th gear at 60 mph (manual) to keep it completely smooth otherwise it hesitates. I don't like driving at that rpm till its warmed up, After todays driving Im thinking of not driving it anymore until Friday after next when it's booked to be dyno tuned.

HappySalesman

iTrader: (3)

The only real issue I can see with letting your car idle is the fueling is probably very incorrect and it could be running so rich that it's excessively washing the bores... but once your car is tuned properly I can tell you that 30sec-2min of idling isn't going to damage your motor. If it did, why would manufacturers install remote starts with 12+ minute runtimes from the factory?

TimsLS1

Thanks that's a good point to make.

Ls7colorado

iTrader: (3)

Modern engines can idle for YEARS.... cop cars get beat to death and spend over half there run hours at idle.
The diesel AND gas trucks at my work NEVER shut off all day long, they idle at every stop throught the day... cold hot whatever.... they all go to 300-400K miles and the engines are still fine when the truck falls apart.
Heck we have some red lights that are 2mins long here lol

G Atsma

I fully agree with this, but I think the main point above is not to let it idle much while breaking it in, especially with a bad tune where over-rich conditions are bad for engine health.