Dyno run leaning off ????

[Mattw]

Hi all, I had my car dyno'd a month ago and I got 171 bhp at the wheels but he had to stop at 6300 rpm due to it starting to lean off. any ideas why??:scratch:
It was running 11.2 all the way through until then??
Thanks

[mk5gtt]

Hi mine was the same 176 bhp and at 7250 revs started to lean off dont know if its the carb bowl emptying or just the jets not quite set right. Dont have the problem anymore as ive gone down the efi route and its alot better now.

[Mattw]

http://i1078.photobucket.com/albums/w494/badass138/3AE4083B-E5D1-439D-96F9-3423CCC75C87-185-000001887054A551_zpse2a1e9c9.jpg

http://i1078.photobucket.com/albums/w494/badass138/4A1331A2-4502-424B-91AD-D7CB2773F579-185-000001887E2096FE_zps0fb51d7b.jpg

[Mattw]

Hi mine was the same 176 bhp and at 7250 revs started to lean off dont know if its the carb bowl emptying or just the jets not quite set right. Dont have the problem anymore as ive gone down the efi route and its alot better now.

cheers for reply so not just me then be nice to find out what it could be tho :)

[mk5gtt]

Whats the spec of the carb and the condition of the fuel system?

[mk5gtt]

When you think of the size of the carb bowl on a good power run it could be emptying and if the fuel system is not in good service it might not be keeping up meaning you start to lean out at the top end

[Mattw]

1.25 second stage
0.9 ac
can remember the rest off top of my head doh!

[Mattw]

fuel filter was changed a couple of years ago but have only done prob 1000 miles in her.

[Brigsy]

Probably the bowl emptying, you need a bigger needle valve or an adjustable fpr

[Mattw]

Probably the bowl emptying, you need a bigger needle valve or an adjustable fpr
thanks for reply.
Ive bought a adjustable fpr but was a bit dubious to fit it with out getting a bit of info on them?
would I need to change both or not??
cheers

[Brigsy]

Providing its a malpassi reg just get it whacked on. Use the standard 1.7mm needle jet and set the base pressure at 6 psi.

[Mattw]

Providing its a malpassi reg just get it whacked on. Use the standard 1.7mm needle jet and set the base pressure at 6 psi.
Ok thanks.