Surrey RR result

[andyoleary]

Hi all,

Ok, taken me some courage to post this but I would appreciate some CONSTRUCTIVE comments....

Myself and Mike Gaut had our RR power run (LT auction) with Charlie on Weds this week. It was the first time for me and my Tusc so I was quite literally bricking it but the car has just been serviced and I had seen the top end myself - no cam lobe or follower wear so I thought "why not....let's see what happens" although I have never taken the engine about 5.5Krpms myself in my short 5months of ownership...

First run and there was a small bit of black/grey smoke emmitted from the exhaust towards the top end of the run - not white/blue mind you. This seemed to burn off and the 2nd run was clean.

The power results were ok and the max torque was reasonable but there did seem to be a couple of areas of concern in the min-range rev's and towards 6.3Krpms. Charlie reckoned there was a knock or two and a possible mis-fire and wondered if a mapping session with the likes of Austec might be worth a look. The oil usage is pretty low (approx half litre every 200/300 miles) and, to my knowledge, there are no issues with the valves etc, etc.

Check out the graphs below


This second graph shows the AFR readings as being quite erratic and quite lean.

Cheers!
Andy

[Steve_T]

Good power and torque, but she's running quite lean in places.

Steve.

[andyoleary]

Thanks Steve, that's the thing - would the lean running be indicative of a mechanical issue (valves perhaps..) or a fuel-control/mapping issue? The engine is a RR by the factory and, to my knowledge, has the original map/chip from day one.

Andy

[Steve_T]

Lean running seems quite common with the S6s I've seen on the rollers. It's a fueling issue, so you would have to correct it in the map. In the south only Austec have the necessary kit to map the S6. I've seen comments on other threads that say there's not much power to be gained through mapping S6s, given your motors power output ~25bhp up on most, that's even more likely to be the case. However running an engine lean is not a desirable thing, so it might be worth doing just for that reason.

Steve.

Edited by Steve_T on Friday 15th December 11:57

[andyoleary]

Thanks again Steve, I was hoping this was the case. How about the knocking? Could this be attributed to the lean-running too?

Andy

[Steve_T]

Best to get Paul to have a look at what's happening with a full range of diagnostics hooked up to her.

Steve.

[andyoleary]

Yeah - agreed. I have mailed Paul/Mark and will call them later today to chat hopefully,

Cheers Steve,

Andy

[whitey]

Here is mine for comparison from last week on the same rollers. I have 2500 miles on a fresh full factory rebuild to S/Saggy spec, so should get a few more bhp as the engine loosens up. I also have a higher rpm slight possible misfire that needs investigated, but otherwise perfect fuelling.

Let me know how you get on at Austec.

[andyoleary]

Thanks Whitey, very interesting. You have a smoother power curve than mine and the AFR readout is a lot better. Still notice a very slight dip mid-range - curious that, was your chip changed/mapped already following the re-build?

Cheers

Andy

[whitey]

I had a new chip from the factory to latest S/Saggy spec, but my previous Red Rose chip also had perfect fuelling. My engine is showing 312 lb/ft torque so hopefully a sign of a good engine build!

[andyoleary]

Sounds good! Long may it continue mate,

Cheers

Andy

[GingerNinja]

Would be quite handy if anyone with photoshopping/image editing skills could overlay the two graphs from both cars aboce for a more direct comparison.....?