Mobile RR conundrum

[DangerousDerek]

I know for a fact my car is faster than it was when I first had it mapped at Bailey Performance. That day it made 330 bhp at the Rev limit of 6300 rpm. The next day it ran 108 mph terminal speed at York. Since then the engine has fully bed in, freed up and now runs nearly 116 mph terminal. That's quite a difference.
So I was at Total Retro this weekend and there was a mobile RR so I thought a great opportunity to see if my theory was correct and I had a fair bit more hp.

The man told me the RR was good for 1200 bhp and had been used up and down the country at all sorts of events etc.
The car was strapped on, I told him it was good for 6200 rpm. He had some problems with the electric supply and claimed he was getting static shocks off my roll cage so we used my jump leads to earth the car to the rollers.

Then the power run gave this



I was happy to see the power get to 292 at under 5300 rpm but can not figure out why the sudden drop from there.

Any theories?

[DangerousDerek]

Here is the run from Dales for comparison. Climbing all the way to 6300

[DangerousDerek]

I am not in the slightest worried and know the car will perform on the drag strip next time as it has all this year. Low 12's are easy now and I can push it into the 11's at 115 when needed.
It's just this graph that confused me. The sudden drop off in torque and power at such a low rpm.

I want to just get through to September with enough reliability and to give me the biggest chance of winning the NSCC after competing in the series for a good few years now.
Then I will go see Dale and get a fresh mapping and check over and head to Surrey Rolling Road for a shootout with the usual suspects. Then we will see

[DangerousDerek]

Had a chat with Dale last night and I need to check the breathing on my petrol tank. We have a theory that the tank is suffering vac and possibly affecting fuel pressure. I have rich ended the map top end as I was seeing over 13:1 on the strip flat out. But I know the cap was loose on the rolling road so maybe it was very rich top end. I will do a compression check also as Alun suggests. Be intereresting to see at this stage anyway.

Watch this space.

[DangerousDerek]

Hoofa said:

What cam have you got in it ?? Think I would be inclined to get another run done on another dyno, doubt it's wheel spin ,

Edited by Hoofa on Tuesday 26th July 23:33

It's a mech Crower 50304 and went to 6300 easy first time round. Something strange happened on this rr on Saturday. I have some ideas after chatting with Dale.
I will also be doing a compression test on Friday