Should it do what is says on the tin??

[davidd]

Morning, I've been pondering this one for some time, and my recent investigations in Cerberas have furthered my ponderings to the point where I thought I'd ask you lot for some input.
BHP, my Griffith is supposedly 340, I am very happy with the way it goes and have never had it on a rolling road or dyno, however I suspect if I did I'd see somewhere between 250 and 270bhp. 4.5 Cerberas, according to the factory..420bhp, but as the rolling road shootout showed that is not the case.
Now as I said, in real work driving I'm very, very happy with the performance of my car but if I had the engine out, stuck on a dyno and it came out at 260bhp would I have a case to go back to TVR and ask them for the other 80bhp?
After all if I bought a case of beers which said there were 24 inside and got home to find there was only 18 I'd be very upset and would do something about it.
Any experts on the sale of goods act care to comment?

[fish]

Speed 6 engines normaly produce what they say I gather - 360bhp

[davidd]

quote:
Speed 6 engines normaly produce what they say I gather - 360bhp

Indeed, as does the 4.2 Speed 8

[nubbin]

I spoke to Jools at Joospeed about this, and he said the Rover V8's were producing 20-30% less than specified, but the AJP engines, inc. S6 are very close to specification - say 10-20 bhp less. Where's the best rolling road in the South Yorkshire area for testing?

[squirrelz]

I think Joolz said he uses one just up the road. John someone-or-other motorsports. Can't remember exactly.

[gadgit]

When they test on a rolling road, sometimes you get the horse power produced at the back wheels and not what the engine produces. This will allways be considerably less than the power of the engine, so be sure they give you the right figure, some, or most of you will of course be allready aware that this is the case.

gadgit.

[davidd]

quote:
When they test on a rolling road, sometimes you get the horse power produced at the back wheels and not what the engine produces. This will allways be considerably less than the power of the engine, so be sure they give you the right figure, some, or most of you will of course be allready aware that this is the case.

gadgit.

Indeed, which is why I'd like a dyno test instead of a rolling road one. However most rolling roads will try to work out power losses for you (not sure how I think they take readings when the car is freewheeling) to then try to provide a more accurate end figure (if you see what I mean).

David

[Graham]

Erm wouldnt a Dyno Test involve taking the engine out of the car??... seems excessive just to see how much power its got ....

G

[zubi]

tstststs as I'm still saving for a 4,5LW ... If I pay for 420 horses I WANT 420 horses!

[davidd]

Yes a dyno test does involve taking the engine out, and yes if I'm paying for 420 horses I do want them.
TVR should come clean on it, if they are not putting out the power they are supposed to be then fair enough, change the specification sheets.

[kevinday]

Most manufacturers will quote the best they have seen for that type of engine. No two engines will give the exactly the same figure. Atmospheric variations can cause huge variances as well, cool and damp air will give much better results than hot dry air. Rolling road tests will be 'unfair' in that the atmospheric conditions are not usually ideal because the car is stationary and all the heat produced stays somewhat in the vicinity creating high temperature air going into the engine. Rolling roads should be used for before and after comparisons, not outright measurements. A dyno test is the only way to get an accurate power output figure.

[RUF 3]

I think it may take more than ideal atmospherics on a good dyno day to see 340bhp out of a 500 Griffith. In fact could anybody even prove an honest 300 ? OK, so advertising needs optimism but to overstate reality by about 20% ?

>> Edited by RUF 3 on Tuesday 7th May 16:23

[buzzsaw]

There must be some Piston Headers out there who have had their cars on rolling roads....lets hear the results.

[JonRB]

Maybe these engines need a good stream of nice dense air to make 320bhp. Very dense. Almost forced induction, in fact?

Anyway, what does it matter so long as the performance is as advertised? (Which it appears to be)

[davidd]

quote:

Anyway, what does it matter so long as the performance is as advertised? (Which it appears to be)

Indeed a very fair point, but just think what it would be with all the horses.

[david beer]

I put my griff 500 on a rolling road, felt really miffed(polite version) until the drive home and thought its still bloody quick. Maybe the adverts should go something like "goes like a 340 bhp car".
The guy after my session was in a Scooby, he was most interested and suggested i had a dog!

[2 Sheds]

TVR figures are for bench dyno, (with no ancillaries)The Griff 500 on a bench dyno should make about 285 bhp this would equate to about 265 at the flywheel, 210 @ wheels on a rolling road. as TVR more recently claimed 320 they are only 12% out, the earlier cars (340bhp) make slightly more (275 on a rolling road)
Torque figures are around 300 and its these that count !
I have taken these figures from many dyno sessions.
Tim Lamont.

[johnmckenzie]

quote:
I spoke to Jools at Joospeed about this, and he said the Rover V8's were producing 20-30% less than specified

Back in 1993, I had a 450 SE wedge which was quoted by TVR as producing 319 BHP. Due to excessive wear on the cylinder liners at 26,000 miles, it had to go back to TVR for a full rebuild. The 450SE's were always prone to pinking as the engine was in a fairly radical state of tune and following TVR Power's advice the camshaft was changed to a slightly less wild version and the compression ratio reduced a tad by skimming a couple of thou off the pistons. Following rebuild, it was then broken in on TVR's engine dyno and then run up to power - the result was 299BHP peak power (I still have the dyno sheet). Bearing in mind that the engine had just been detuned a tad to overcome pinking problems the original 319 BHP claim would have been accurate. Of course, it could have been a bent dyno but I'm sure that would never be the case

Regards

John McKenzie

[dannylt]

quote:
tstststs as I'm still saving for a 4,5LW ... If I pay for 420 horses I WANT 420 horses!

Well, you most definitely won't get it. Not even for the Red Rose engine option.

[Roadrunner]

According to mag reviews, TVR are also dishonest about the vehicle weights too. Measurements confirm they actually weigh 100kg more than official specs.

If you take Joo's comments on board about engine specs being 20-30% exaggerated, then add on the real 10% extra weight, the power to weight ratio's work out totally different: 30-40% less than advertised.

This is plain dishonesty. Doubt it will stop some TVR fans quoting imaginary figures though.

>> Edited by Roadrunner on Sunday 16th June 17:29