Discussion
It must always be remembered that the figures from any 2 Rolling Roads will differ, they are primerily intended as a comparison indicator to show that tuning work has either worked or not during development and not as a fixed scale measurement of performance. TVR may well be quoting figures from what is known as an "optimistic dyno" it all depends on the manufacturer of the Rolling Road with some makes being well known as being "optimistic" and does not neccesarily indicate sinister doings on TVR's part (It is always best to quote the highest figures though and all manufacturers do it) and if they quote them you can gaurentee they've got the graphs to back them up !!!
I realise there is variation and experimental error on these things as I've had a couple of engines built for me before, my concern was the level of variations from the results I've seen.
The figures I've seen were mainly from AJP8 4.5 engines which are quoted at 420 Bhp.
The best was 71 bhp down, the worst 107 bhp down!
That's more than a bit of variation and must surely thow doubt over the production tolerances in the engines?
One possibility is that most manufacturers tend to quote the BHP at the flywheel, and when you measure on a rolling road it is measured at the real wheels (or front wheels if it's not a proper car)which will always give a lower reading due the power taken up by the drivetrain.
However you would expect that the drop would be consistent.
You can sompensate for drivetrain losses by doing a coast down run to measure the losses.
This was done and these figures are the calculated flywheel figures.
My point is that TVRs are always touted a "performance bargains so you have to forgive them a few rough edges", so if you don't have the performance / power you thought you'd got???
Clearly you wouldn't be fussed about a few BHP, but 25% down?
Over the last Three years I have been involved with rolling road testing on some 14 Griff 500 cars. I always use the same rolling road this rolling road is certified to ensure an accurate reading. I have done Griff 500 HC's and normal 500 both serpentine and not, some cars were brand new some had covered up to 50k. I have never seen a standard car read more than 285 bhp at the FLYWHEEL. My advice to anyone having his or her engine tuned is get it power tested first before any work is done then you know what you are paying for. There is a great deal of rubbish out there people will try to sell you which does not work.
Bertie, TVRs are indeed the performance bargain of the century. You've obviously never driven one, because if you had you'd be more interested in how they go than how many bhp you can or can't boast of down the pub. 
I love my Griff, it'll blow most things into the dust, it looks gourgeous, has a wonderfull V8 soundtrack and the cabin is a leather fanatics fantasy, and... it cost less than £40 grand. Remeber performance is not measured in bhp 
Rich...
I love my Griff, it'll blow most things into the dust, it looks gourgeous, has a wonderfull V8 soundtrack and the cabin is a leather fanatics fantasy, and... it cost less than £40 grand. Remeber performance is not measured in bhp Rich... Not that it's particularly relevant, but I've owned 5 TVRs over the last 12 years, and it's about to be 6 when my Tuscan arrives.
They have been, S2, 400SE, Chimaera 4.0, Griffith 500, Cerbera 4.2, 3 years with a Ferrari F355 and around October 8th a Tuscan. Also during the same time some track day cars (2 Caterhams and an Elise 160.)
So based on this I do consider myself qualified, maybe more than most, to talk about performance cars.
Rich... I do find it entertaining that TVRists will quote fantastic power figures when it suits and similarly ignore them if it suits. You're not that bothered if it doesn't have as much power as is claimed, or if it's rather heavier than claimed. Hmmm.
After spending 40-50 big ones I would be bothered, not based on a down-the-pub "mine's got more power" type row, but based on the fact that I'd just spent 40-50 grand. I think that's reason enough. Yes, I have driven a few of them (Trevs) and no, I couldn't tell the difference because they weren't driven on the same day, but surely it's the principal of the thing that counts?
I'm not starting a slanging match, it's just that the political manoeverings are very entertaining. Like arguments with Schumacher fans...
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