5.0 RV8 doent run smooth when (town) driving at low speed?

[leylandracer]

Just wondering if it's norm or not for the 5.0 NCK RV8 fitted to the Marcos to run smoothly at town driving speeds Funny enough my TR8 5.0 V8 had the similar trait, i.e. say driving at 30-40 mph with next to no throttle it wasnt happy, nothing major bad but it will pull and jerk, dab the throttle a bit and fine, with the TR i put that down to the Quad Webers/Cam etc but i was thinking the EFI whould/should be better at town driving? Any thoughts Norm or

5.0 NCK Eng spec;

Compression; 8.9 – 9.0 to 1.
Bore; 94m/m
Stroke; 90m/m
Cam; Kent Cams
295 degrees duration
Cam lift = 6.98mm
Hydraulic profile
Valve Springs; Duel
Heads; Gas Flowed, Ported and - polished c/w big valves
Inlet Valves; 1.700” dia
Exhaust Valves; 1.450” dia
Inlet Manifold; Gas flowed
Pistons; Cosworth
Piston Rings; Land Rover
Plugs B7 ECS
ECU; 500 Cat Chip
Tune Resistor White

[kiwicar]

Hi
Is this a modified/ re-chipped Rover ECU? if so it is the ECU, they react to slowley for a tuned rover V8, see Ian Andersons many posts on the subject.
Best regards
Mike

[leylandracer]

Yes its a Rover ecu with the de-cat chip

[kiwicar]

Aparently the ECU doesn't update from all the sensors rapidly enough to cope with low/ part throttle transitions and there isn't enough resolution to cope with a tuned engines requirments, hence the problems, cheepest fix would be an Extra efi ECU from Phil, He was going to do a plug and go kit, not sure if it is ready yet.
Best regards
Mike

[Ian Anderson]

Hi

I'm running a Lucas 14CUX Ecu (Hotwire)
Mine does as you say - great inder power or when over 2000 rpm
Low revs and low throttle = bucking bronco (Light car lightened flywheel and JE built engine and 102 cam (loadsa overlap and 0.5 lift/ cutouts skimmed to raise compression etc))

I did see Phil has now got a plug and play ECU out but have not bought one - yet


see
http://www.extraefi.co.uk/RV8_Kits.html

Ian

[daxtojeiro]

Hi,
the shunting has been put down to lots of issues, but basically the way around it is ignition and fuel control. The only way to achieve that is with an aftermarket ECU.

The Plug-n-Play Rover V8 ECUs are out, selling really well, V8D are marketing them, Im just building them
www.v8developments.co.uk
cheers,
Phil

[adamnreeves]

Nice spec engine. The shunting is probably down to too much timing advance. I am using Megasquirt. Any issues like this can be dialled out quite easily.

[leylandracer]

Thanks for the replys, I have spoke to V8D and tempted

A bit off topic What do you reckon with the spec of the Marcos NCK RV8 compaired with such as a TVR Grif (spec in the 1st post on this thread) it deffo isnt as quick as my TR 5.0 RV8
I think Marcos quoted 320 BHP but its been said that 280 max is more like it Maybe a aftermarket ecu such as Megasquirt would free up some extra horses?

[leylandracer]

Just toying with some plans/upgrages for the new year

I think the Extra efi ECU is on the cards.

What inlet would be the best to release a bit more power? Spec on first post:

Ideas are:
A/ ACT Tripple or Double CF plenum ect (Looks nice )
B/ JE engineering twin plenum (68mm throttles)
C/ John Eales Crossover inlet manifold, (not really sure if these will fit inder the Marcos bonnet & expensive )
D/ any other thoughts

As mentioned, The marcos prob as around 280 ish bhp, compared with the TR7V8 (Quad Webers) i had, it does feel slow

Any ideas welcome

[adamnreeves]

You running a standard plenum chamber? I using an ACT carbon fibre one with a jaguar/ford type throttle body with a 76mm throttle. Seems to go quite well. If you want a big hike then go for full throttle bodies conversion. Get the ExtraEFI ECU and run in alpha mode.

[CastleMGBV8]

Steve,

Firstly get the Megasquirt, this gets rid of the air flow meter which cannot cope with the exhaust gas reversion which is a factor of using a big cam with large overlap.

Once set up properly it should run a lot better however with a plenum EFI system you will still get some negative effect at low RPM of the reversion pulses coming back into the plenum, but drivability will be vastly improved,
easpecially as you can fine tune the advance curve for the ignition.

In your engine spec you state only around 9/1 comp ratio which sounds a bit low, 10/1 would liven the engine up and possibly a bit more to offset the effect of the overlap, your dynamic compression ratio must be quite low at the moment.

Inlet manifold gasflowed does this include the trumpet base with larger trumpets and the throttle body opened up to 71mm, the 5.0 engine really needs better flow in this area to achieve full potential.

I also assume that the quoted cam lift is an error at 6.98mm. or not total valve lift when multiplied by the rocker ratio of 1.6/1 which would give a more normal figure of 11.168mm. but still quite low, I would expect something in the region of 12-14mm. with duration of cam.

What does NCK stand for?

Kevin.

[leylandracer]

You running a standard plenum chamber? I using an ACT carbon fibre one with a jaguar/ford type throttle body with a 76mm throttle. Seems to go quite well. If you want a big hike then go for full throttle bodies conversion. Get the ExtraEFI ECU and run in alpha mode.

As standard as Marcos put it together I dont reckon the John Eales set-up will fit, Space is limited on the drivers side?

[adamnreeves]

My 285 duration cam gives 12.11mm lift.

Steve,

Firstly get the Megasquirt, this gets rid of the air flow meter which cannot cope with the exhaust gas reversion which is a factor of using a big cam with large overlap.

Once set up properly it should run a lot better however with a plenum EFI system you will still get some negative effect at low RPM of the reversion pulses coming back into the plenum, but drivability will be vastly improved,
easpecially as you can fine tune the advance curve for the ignition.

In your engine spec you state only around 9/1 comp ratio which sounds a bit low, 10/1 would liven the engine up and possibly a bit more to offset the effect of the overlap, your dynamic compression ratio must be quite low at the moment.

Inlet manifold gasflowed does this include the trumpet base with larger trumpets and the throttle body opened up to 71mm, the 5.0 engine really needs better flow in this area to achieve full potential.

I also assume that the quoted cam lift is an error at 6.98mm. or not total valve lift when multiplied by the rocker ratio of 1.6/1 which would give a more normal figure of 11.168mm. but still quite low, I would expect something in the region of 12-14mm. with duration of cam.

What does NCK stand for?

Kevin.

[leylandracer]

I think NCK did a lot of GT racing and still do? below is a piece from the Marcos forum

Quote: The NCK engine can be identified by the lack of the advance retard (they have a different distributor) and the "Marcos" Rocker covers which were made to clear the highlift rockers and only made by NCK. In reality the NCK engines were made for 1995 fuel and the same engine today would use a cam with a very different profile. Graham Nash - formerly NCK - is still around and could refresh the engines with a new cam for todays poorer quality fuel to bring the power back towards the published figures and make them more friendly at low speed.

Just got this reply back from Kent Cams who supplied NCK:
Quote:
Hi again
I still stand by my lift figures. non of our profiles have 14.00 lift, even the full race



Spoilt for choice, lots of £££ though

[CastleMGBV8]

Steve,

The cam lift will always be substancially less than the valve lift because of the rocker ratio,usually 1.6/1 on Rovers but your ratio may be different if you have custom rockers if so what is the ratio?

For example my Crower 50232 has .488" lift at the valve, the lobe lift will only be .305 or approx 7.75mm and thats a fairly mild hydraulic cam.

What about the comp ratio?

Kevin.