How fast or not should a V8S be?

[Andy Lynch]

Hi

I am unsure if my 4L V8S is running as it should? I have timed if from 30 - 80 in 3rd, on the flat and it takes just under 10 seconds.

My car has a standard 4L engine with no modifications, I would appreciate anyone with a standard 4L V8S to give theirs a blast and let me know if mine is ok or a bit slow.

Or if anyone has some more information of times between certain speeds in certain gears, I know it should do 60 in 5 secs or so, but that I guess was with a new car a new engine someone who can change gears and some one who doesnt mind killing their car.

Thanks

Andy

[Barkychoc]

I have had my engine rebuilt and now its fk me fast.
It is far far quicker than it was before - mainly due to a worn cam I think.

I haven't done any timings - I intend to soon - another member asked me to do this and I just haven't got round to it.

Welcome by the way

[zombeh]

I have a totally different ECU on mine now with modern ignition (though the ignition map is currently set to "extremely safe". I'll try and find enough empty road to do that tomorrow though.

Are those speeds according to TVR's random number generator, or something more accurate?

[Andy Lynch]

no, mumbers generated by me looking at the speedo and shouting start and stop to my daughter operating the stopwatch, If some one is reporting major diferences with another standard engine car I will know I have some spending to do!

[GreenV8S]

I went through a very similar exercise with my V8S when I got it. It's very hard to get consistent measurements so I did a couple of dozen runs measuring the time to cover 10 mph increments from 30 - 80 and then plotted them all together. The average seemed to be about 8 seconds, although I measured under 7 seconds on one run and nearly 10 seconds on another one. But I suspect these were simply experimental error. You might be tempted to conclude that your car is about 25% down on power if it's taking 10 seconds. But bear in mind that the speedo isn't particularly accurate. Some years later I found that mine was reading about 10% high. So really I was measuring something line 30 - 73 mph not 30-80. You need to know what your speedo error is before you can compare the figures. Also, measuring intervals as small as this means that small delays starting or stopping the timer can have a big effect. So make sure you start below 30 mph and use the same technique to start and stop the timer. My measurements were taken one-up with half a tank of fuel. The weight of a passenger and an extra half tank of fuel might make more difference than you expect.

[Andy Lynch]

Thanks GreenV8S

I suppose, as I dont have anything to compare my car against, I dont know if its right or down on power. Most of the reports I have read suggest that the car should be fast, and to be fair it is, but perhaps not as fast as the reports suggest. So before I go and spend a shed load of money trying to solv a problem that might not be there I am trying to decide if there is a problem. If you get my drift. So all advise / speed times are geatly apreciated

Thanks

Andy

[Andy Lynch]

How did you manage that? I hope it was someone elses fault, and I hope its fixable, judging by your last post I assume you are going to, good luck

Andy

[mycroft]

A friend that has a timing company tells me iphone has a timing app ( 0-60 i think ) that might be a way to go to get a comparison with other owners .

[GreenV8S]

If you want to get an accurate comparison, an accelerometer based logger is the way to do it. G-Tech do some inexpensive ones, although I can't say I was impressed with the one I bought. Race Tech do some much much nicer ones that do clever GPS integration to take out accelerometer drift, but they have a much nicer price tag.

A hand-held stopwatch based on the speedo is pretty hard to beat for value-for-money, but you need to know the speedo calibration first and also be careful how you start/stop the stopwatch. Calibrating the speedo is also easy and cheap. You don't *need* to spend a lot of money on this, but it's much quicker/easier to do with the right equipment.

[phillpot]

......Or perhaps we should all have a day out at a "Run what you brung" day and compare quarter mile times !

Accurate timing and great fun

[dbv8]

phillpot said:

......Or perhaps we should all have a day out at a "Run what you brung" day and compare quarter mile times !

Accurate timing and great fun

The only true way to test your power and performance.
Hopefully i will be at Shakey this Saturday and York on Sunday. Then a couple more RWYB before the Ultimate TVR Shootout at the pod on 9th July. We need to see more of you 'S' guys there.

[Ragtop]

dbv8 said:

phillpot said:

......Or perhaps we should all have a day out at a "Run what you brung" day and compare quarter mile times !

Accurate timing and great fun

The only true way to test your power and performance.

No - it's the only true way to test how brutal you can be with the clutch and tyres!

Seriously though, in gear acceleration times take the driver pretty much out of the equation, make reasonably accurate comparisons over different parts of the rev range, and are probably more relevant to road use, so they do have something to offer.

All IMHO, of course!
Graham

[dbv8]

Of course I agree. I am just a drag strip junky. Terminal speeds are an excellent power indicator at the strip however

[jimed]

I'm a bit late on here Andy but it might be worth getting the engine set up checked (eg timing, etc) to ensure that it is as it should be before going too much further with it. As the car gets older things like ignition leads get tired and need replacing and with some of the V8s the cam can wear which causes a drop off in performance. This wear can happen after maybe 30k miles but often much higher mileages are achieved with no problems so it might not be an issue for you - and even if there is some wear if you are happy with the performance leave it for now and enjoy. One other thing that I was told about by X Works was that the factory did on occasion fit cheap coils which can have a problem with the plastic round the HT lead getting soft and porous which can have obvious issues - they quite gently scraped away some of the bakelite on the coil on my Griff with fingernails so it was quickly replaced even though I hadn't had any (known) problems with it at that stage. In the meantime enjoy!
Jim

[Ragtop]

Okay, here you go:

30 - 80mph (on speedo) in 3rd gear from a steady 30mph, mean
of two timed runs in opposite directions...

8.9 seconds.

Autocar got the road test car to 80mph FROM REST in under this time, so either we've got tired examples, or the road test car was 'a bit special'.

Regards,
Graham

[Podie]

A rolling road will give you an idea..

[GreenV8S]

Ragtop said:

8.9 seconds.

Autocar got the road test car to 80mph FROM REST in under this time, so either we've got tired examples, or the road test car was 'a bit special'.

Regards,
Graham

You have to remember that on a 0-80 test you would be going up through the gears and the engine would be in the power band the whole time. Doing an in-gear acceleration test you spend a long time at low revs and only hit peak power towards the end of the run. You can't really compare the two figures. I think the in-gear acceleration run is the more useful measure, actually.

The press car probably did have considerably more power than the ones off the production line. TVR had some very nice 4.3s around at the time.