Power figures

Author
Discussion

bertie

Original Poster:

8,368 posts

257 months

Thursday 6th September 2001
quotequote all
Has anyone had their car, Tuscan or other TVR, on a rolling road to test the power output. I hear rather frightening stories of the outputs being nowhere close to the specifications given by TVR.

RichB

46,547 posts

257 months

Friday 7th September 2001
quotequote all
Yes, plenty of people put their TVRs on rolling roads and particularly on the V8 cars bhp. is not as high as TVR quote. However (or perhaps I should say frighteningly) performace commonly is Rich...

mel

10,168 posts

248 months

Friday 7th September 2001
quotequote all
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 !!!

bertie

Original Poster:

8,368 posts

257 months

Friday 7th September 2001
quotequote all
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?

.mark

11,104 posts

249 months

Friday 7th September 2001
quotequote all
Whilst I agree that what the manufacturer states should actually/hopefully be near the mark, if my car continues to give the instant grin factor everytime I drive it I really couldn't care less if TVR said it had 250BHP or 2500!!

mel

10,168 posts

248 months

Friday 7th September 2001
quotequote all
bertie. fair one !

JSG

2,238 posts

256 months

Friday 7th September 2001
quotequote all
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.

bertie

Original Poster:

8,368 posts

257 months

Friday 7th September 2001
quotequote all
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?

hawhaw

11 posts

251 months

Friday 7th September 2001
quotequote all
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.

RichB

46,547 posts

257 months

Friday 7th September 2001
quotequote all
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...

Jason F

1,183 posts

257 months

Friday 7th September 2001
quotequote all
Who gives a t**s what the BHP Figure is anyway ? It is 0-60 time that is important to me ( less than 5 secs is fun fun fun ) .. Plenty of cars with far higher BHP go a LOT slower all through the range..

bertie

Original Poster:

8,368 posts

257 months

Friday 7th September 2001
quotequote all
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.

RichB

46,547 posts

257 months

Friday 7th September 2001
quotequote all
You should know better then Rich...

mel

10,168 posts

248 months

Friday 7th September 2001
quotequote all
well saved !!

ahonen

4,860 posts

252 months

Friday 7th September 2001
quotequote all
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...

Stu H

5 posts

245 months

Saturday 8th September 2001
quotequote all
hawhaw I would be interested to know what the percentage power loss was measured at due to transmission losses etc. on a Griffith 500. i.e. what % of the BHP at the flywheel is lost compared to rear-wheel BHP. 18 - 23%ish ?? thanks in advance ---- regds Stu

hawhaw

11 posts

251 months

Sunday 9th September 2001
quotequote all
I would say usually about the 25% mark. Most I have ever seen was 30% but that was on a S series car.