Alright here's the deal, my old setup was a MS3 cam, PRC LS6 nonmilled heads, 90/90 fast and was tuned for that setup. Roll forward 3 years or so after a spun rod bearing to my new setup. Currently going into my car is a forged 347 with a 235/243 cam from Pat G, the old PRC LS6 heads milled to 60cc, every bolt on and accessory you can think of with my PCM on the old tune. So now I have higher compression, I think around 11.3 or 11.4:1, different cam, and I need to break the motor in.

Question is really, what do I do? There's no speedshop close to me that I trust, I live in Kansas City MO, but I do have a tuner with a good rep pretty close by. Do I rent a dyno to break in the motor and have the tuner there monitoring? Or can I risk just breaking in the motor without a tuner and getting a hold of him later when it's feasible for him. I just don't know how to juggle all this with winter, not having weekends because of drill, and everyone all together. So what's everyone's opinion lol?

 

I would talk to Patrick G about doing a mail order tune to get you safe to drive the car before you get it tuned.

 

The tune thats in it should be fine to baby the car to the dyno and get it tuned. As far as break in just warm it up to operating temp take a couple laps around the neighborhood then change the oil.

 

Here's what I see

MS3: 237/242 .603/.609 112-114LSA
New Cam: 235/242 ???

I know you added some compression, but the airflow for your setup does not appear to have significantly changed. Without some additional detail, I think you might be splitting hairs on the differences between the two.

If you had a razor sharp tune before, or if you made a significant change in LSA between the two cams, you may notice some low end and drivability variance. That said, I think if you start the car and it idles well, you should have adequate fuel in the existing tune go out and flog it on the street to seat your rings. It would be nice to have a wideband O2 and/or log data to see where the AFR falls and whether you have any KR.

The LS6 heads should not have required a lot of spark advance as it was, so the change in compression from ~ 10.5:1 up to 11:1 may not change the timing much at all.

Above all, do what you can to get it to operating temp, then quickly start loading the rings to break them in! You can always baby a car on a bad tune, but you generally can't put enough of a load on a new setup without some baseline tuning. I think you have that in place.

Good luck!

 

Thanks for all the good info. The cam is a 235/243 .621/.624 with 111 +4 advance. I think I might rent a dyno and break it in, thanks for your advice Hammertime.


Rusty

 

As long as you are still running the same injectors from the previous tune you should be fine to break it in with that. There should not be a huge difference in fuel and spark requirements between the new and old setup.

 

I'm running the same injectors as last time. The only thing I'm changing fuel wise is I'm changing my stock fuel pump for a single pump Racetronix.