I want to just share something I've noticed, I'm by no way an expert or know for sure what's going on fwiw. This might be specific to British Columbia as I think eastern canada has a bit better gas but if you're in the car community here you know our fuel is HORRIBLE. We only have 91 other than Chevron claims to have a 94 but it typically runs around the same or worse as Shell 91, which is what most tuners, car guys, forums, enthusiasts, etc, all generally know. Our 91 is worse than 91 in the states and lots of our car guys head down to Washington to get their 92 as it's night and day difference, since Vancouver and surrounding areas are pretty close to the border.


Knowing this, I figured I'd baseline dyno my car on a dynojet and compare it to the vast number of stock dyno jet threads and posts on this board and others. Most cars seem to make 460-475rwhp on a dyno jet on the forum, I suspect most are running 93 but if someone can chime in with 91 stock numbers I'd like to see them. So I figured knowing the difference in power I made when I owned a 2012 c63, I figured on my 2017 I'd be making an easy 440-450 on our fuel. I got on the dyno 3 days ago to get baselines numbers before installing dp and tune, at a place that I have used before and compared to a second local dyno jet (with my old car), both read within a few hp on different days, likely the difference in temperature. There isn't much to manipulate on a dyno jet so no surprise there. We'll call this dyno A. On dyno A earlier this week my bone stock (other than second cat delete) 2017 c63s with 30k km (18k miles) made 410rwhp. We are at sea level here, temperature in the shop was 80F. Thinking either something was wrong with my car or the dyno(since i hadn't visited there since over a year prior with the old car) I decided to book an appointment yesterday at a friends shop that we will call shop C. On shop C dyno yesterday I made 411rwhp and it was like 82F in the shop. At this point I know dyno A an C read comparable and likely dyno B since I used it a year prior. So i'm ruling out the dyno and now thinking my car is hurt. We are discussing maybe it just needs plugs or maybe compression is down in a cylinder, could be anything. The interesting thing is I picked up the car from a service yesterday before the dyno runs and they didn't report any weird stored codes. Not that there would be a stored code for a low compression cylinder or issue like that. Furthermore, when on dyno A earlier in the week we examined the runs and the hp/trq curves look pretty good.

So today I had another local car, a 2015 c63s with 60k km (37k miles) and second cat delete meet me at one of the dyno's. I figured either he makes similar power but that seems awfully odd compared to the numbers I see from the states, or he makes up towards ~450 or more and there is clearly and issue I need to address. After 3 runs he makes within 3 hp of my car on that same dyno. I'll attach the overlay of both our runs below, keep in mid they are on different days from the same week but similar weather (about 3 degrees difference recorded on the days).

There is a possibility our gas is really that bad but I highly doubt it'd be the difference of 60ish wheel hp, especially when my 2012 only made slightly less than the americans cars. Another theory, which myself and a couple of the shops figure could be the case, is that MB knows we have bad gas in this region and we actually see a different tune than other regions. Whether it's a pound or two less boost or a lower timing target, not really sure. Interesting, none the less.

I should mention all the pulls were done in fourth. We did one pull in fifth on my car at first and it didn't make much of a difference in power, so from there forward all pulls on both dynos on the 3 separate days were all done on fourth, just to save from beating on the cars too much.

I'm blue, he's red. Same car, same fuel, same dyno, roughly same temp. Vancouver cars:















Here is two runs back to back on my car from the first day. The second run obviously heat soaked a bit:

 

Thats really weird . I made 367 on the dyno in limp mode last year w/ a tune lol ......... forgot to turn off the traction control and the dash lit up with multiple failures right away . I have yet to retest

 

Wasn't on racing greed dyno was it?

I'd like to see another stock car test, if you loaded the stock tune it would be interesting. The only thing about mine and the car from today is we both have second cat delete and mufflers deleted for straight pipes with AWE valve simulators to trick the car, so no soft limp mode from the stock mufflers wiring (my exhaust was a custom build replicating the AWE Track exhaust). But if there is some sort of back pressure sensor or something messing with the car, that the only other theory I could think of. I high doubt it though. The valve sims take care of the wiring and lots of people run second cat delete.

 

On what mountain is this dyno? 5200 ft elevation?

I often see DA >5000 where we live , elevation of 2100 feet.

 

Obviously the next step would be to get some decent91- 93 oct gas in the car and re-pull at same dyno(s).

Turbocharged engines in general are more sensitive to octane than NA cars, as is commonly known, so not too surpsing bad gas would show more of a difference on a m177 than the m156.