rolling road today

wrighty · 02-17-2010, 05:06 PM

Found out what the rumbling was today it looks like the propshaft joint or diff input vibrating. The lads had it on the rollers but would not give it full beans in case it bust the joint. However on part throttle it showed 250 bhp at the back wheels which is hell of a lot no wonder the prop is giving up. Will get job sorted next week then back on the rollers.
Standard is 230 at the flywheel so 250 at the back wheels must be around 300 at the flywheel , maybe one of you guys can give an approx % loss fromflywheel to wheels. Looks feckin good though I thought it pulls well

Captain Chaos · 02-17-2010, 07:22 PM

Loss depends a lot on the type and often make of dyno, but anything between 15-20% is typical, so yeah your estimate is probably ballpark.

Disappointing that the prop is finding that hard to live with though, it's not like you're putting 75bhp onto something that didn't already have almost 3 times that as standard.

Are they sure it isn't the diff? Those sodding things always seem to give way sooner rather than later when you start turning the wick up... (I hope it isn't, though it'd be a good excuse to go for an LSD!)

02-17-2010, 05:06 PM	#1
wrighty First Lieutenant 52 Rep 395 Posts Drives: BMW 1M Join Date: Mar 2009 Location: Blackpool iTrader: (0)	rolling road today Found out what the rumbling was today it looks like the propshaft joint or diff input vibrating. The lads had it on the rollers but would not give it full beans in case it bust the joint. However on part throttle it showed 250 bhp at the back wheels which is hell of a lot no wonder the prop is giving up. Will get job sorted next week then back on the rollers. Standard is 230 at the flywheel so 250 at the back wheels must be around 300 at the flywheel , maybe one of you guys can give an approx % loss fromflywheel to wheels. Looks feckin good though I thought it pulls well
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02-17-2010, 07:22 PM	#2
Captain Chaos Lieutenant 6 Rep 473 Posts Drives: cars n stuff Join Date: Jan 2008 Location: UK iTrader: (2)	Loss depends a lot on the type and often make of dyno, but anything between 15-20% is typical, so yeah your estimate is probably ballpark. Disappointing that the prop is finding that hard to live with though, it's not like you're putting 75bhp onto something that didn't already have almost 3 times that as standard. Are they sure it isn't the diff? Those sodding things always seem to give way sooner rather than later when you start turning the wick up... (I hope it isn't, though it'd be a good excuse to go for an LSD!)
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