Why is the V8 not faster?

S

SimonV8

New Member
Hi,

I've only had my car a couple of weeks, I really like the feeling of wafting along and I'm not complaining at all but I thought that with such a big V8 engine that it would be faster with quicker acceleration.

I don't know much about engine set up but I know the V8 is used on other faster cars. Is it because of the weight and the gearbox of the P6 or something else.

Which I suppose leads onto the question of how can it be made quicker?

Thanks
 
Is yours auto or an S?
Properly set up in stock form you should really be getting 10 second 0-60 times.
My auto can do it in that, now sometimes it feels like less but I haven't timed it for a couple of years. The only changes I had made at that stage were electronic ignition, which has subsequently been changed for a mallory dual point distributor and high quality leads which was a further improvement..
Electronic ignition kits are very cheap now so this is a quick and easy change to help get the most from your engine..
Your carbs could need a rebuild/service/balance?
No amount of tuning carbs etc will help if you've got a worn cam/timing gear though.
If yours is an auto, how is the kickdown? It should push you back in your seat to some extent, and the car will overtake at most road speeds with ease.
What fuel are you using? Have you tried high octane/super unleaded with the current timing and noticed any difference?
Jim
 
By faster are you referring to top speed or acceleration?
Top speed is mostly a function of RPM, gearing, diff ratios and aerodynamics.
Acceleration is mostly a function of breathing, fuelling, gearing and directly related
to how deep your pockets are.
 
If you have a smartphone you can download 'appdyno' (it's free) and stick it on the dash. It'll tell you a 0-60 time, then we can find out if the car is slow, or if it's a perception.

My 3500 auto will bellow and grunt itself to 60 in 9.3 seconds, which is relatively rapid considering it only uses 2 gears to do it. The 30 to 70 time is around 5 seconds, which looking at autocar is pretty respectable.
 
Hi,

Yes mine's an auto, I'll have to time my 0 to 60, that app sounds great, but there's certainly no pressing me back into the seat going on. I'm talking about acceleration really, I took it for it's first dual carriage way run today and got up to 80 and there felt like there was plenty left.

I've only filled it up once and pretty sure I put normal unleaded in, I'll try the posh stuff next time.

Other than the acceleration, everything else is spot on, engine is super smooth, perfect idle, no knocks or rattles, had a full service and I rebuilt the fuel pump the other night.

Thanks
 
SimonV8 said:
Hi,

Is it because of the weight and the gearbox of the P6 or something else.

Which I suppose leads onto the question of how can it be made quicker?

Thanks
Click to expand...

Groan....not again....always people say its a heavy car, a p6 is in fact quite a light car much lighter by a country mile than any modern contemporary cars ie sports sedan/ family car 1302 KG.

The speed killer is 2 simple items, SU carburators times 2! you can factor in your BW auto box also but that has some advantages in fast changing so long as you manipulate the stick manually.

Fit a Weber 500, you wont regret it


Graeme
 
My 3500s (OK not an auto) is rapid! That's all bog stock. Consensus on v8forum is that properly setup SUs are good for around 200hp? Should be fine on an ickle 3.5...

Get everything setup properly then see what you think. If you still not happy then splash some cash on a four barrel, or efi!
 
Hi Simon,

There are any number of reasons as to why your Rover may not be as fast as it could potentially be. Retarded ignition timing, blocked flame traps / adjoining hoses etc, worn camshaft and timing set, incorrect carburettor settings to name but a few.

The SU carburettors when properly set up work just fine, they have no problem in powering my 4.6, so they a certainly not a limiting factor in the performance of the 3.5 litre.

Ron.
 
SimonV8 said:
Hi,

I've only had my car a couple of weeks, I really like the feeling of wafting along and I'm not complaining at all but I thought that with such a big V8 engine that it would be faster with quicker acceleration.

I don't know much about engine set up but I know the V8 is used on other faster cars. Is it because of the weight and the gearbox of the P6 or something else.

Which I suppose leads onto the question of how can it be made quicker?

Thanks
Click to expand...

Shame Sparky isn't on the road, I could give you a blatt along the Dearne Valley Parkway :D

I have driven a few P6Bs in my time and some are quick even when stock, some aren't.

I was doing some tuning on Sparky and sent an email to clive@autotronixdevelopments.co.uk

"Hi all

I have a Rover P6 with a stage 1 4L V8 in it.

Included in the spec is a weber 500cfm, 4 barrel carb. Is this something you have experience with, and could set up for me?

Regards

Richard"

He replied

"Yes Richard , used to use these in the early nineties (P6 SD1 ??)

Sent from my iPhone

On Aug 17, 2013, at 11:57 PM, RCleal@aol.com wrote:"

He didn't answer the next email which went into more detail about the car, not being a stock vehicle, but he does seem to know what a stock one is, and may be able to set yours up for you.

You can take me for a spin of you like and I can tell you if its right or not.

Richard
 
Thanks all, good news then, now I know she's got it in her I'll spend some money getting it tuned and set up properly.

Cheers
 
It would be well worth checking the throttle linkage first as you might not be getting full throttle even though your foot's buried in the carpet. There are two bushes on the throttle rod under the air cleaner which may or may not be there, this can also affect the kickdown cable adjustment making the shift points wrong.
 
SimonV8 said:
Hi,

I've only had my car a couple of weeks, I really like the feeling of wafting along and I'm not complaining at all but I thought that with such a big V8 engine that it would be faster with quicker acceleration.

I don't know much about engine set up but I know the V8 is used on other faster cars. Is it because of the weight and the gearbox of the P6 or something else.

Which I suppose leads onto the question of how can it be made quicker?
Click to expand...

I think to the uninitiated, the old Rover, with it's low-revving slogging pushrod V-8 can be very different, to all intents and purposes, than smaller more high revving OHC motors. With peak torque at 2500rpm or so, is a very flat curve when compared to more modern engines peaking at 4-4500rpm.

Though I've never really found the Rover V-8 lacking power, perhaps nowadays it doesn't stack-up too well in the traffic light grand prix against cars that have a much better power-to-weight ratio etc. My last P6 (3500S) was anything but lacking in power, with great acceleration and performance all-round that matched the 0-60mph:9-sec, and 122mph top speed. So perhaps you may want to consider an "S" to fulfil your needs?

Of course it could be that your 3500 auto needs some attention with a good service and a tune-up, and a check of those throttle linkage bushes makes a big difference. And then there's the fact that the engine is old and probably down on compression too. Also, I'm sure with a performance camshaft and fuelling to suit would pep-up the motor. I have a performance cam' fitted to my SD1 automatic and I seldom need to go anywhere near the redline; probably up to 4000rpm if I wanted to "go for it", as the cam' gives superb mid-range performance I don't need to rev it excessively.
 
Thanks again, I'll definitely check the throttle linkages as when I did push it the other day my foot was literally to the floor.
 
Had a quick look (it's pouring down) and there is play at the pedal. I've had a look in the manual though and I can't find mention of bushes and can't see them listed as a spares, anyone help out.

Also I suppose I need to check at the carbs to check the butterfly's are opening fully.
 
The main one to look for is 44 in the pic below. It's behind the engine almost buried in the heater box

Richard
 

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On the auto cars it's part number 34 that takes a hammering too as it's right next to the kick down cable (under the air cleaner elbow on the nearside).
 
Definitely the same both ends.
They are very hard and can be quite a pain to push fully home on the car, so some people find it easier to remove the linkage and do it on the bench.
Also I was just thinking if your kickdown isn't set up right, the gearchanges won't happen at the correct road speeds and could adversely affect your acceleration..?
Jim
 
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