Petrol additives

[Donald Carmichael]

I Have an MGB V8 conversion. It had a Rover SD1 engine, number 10A20783, fitted in 1990.
Will this run on unleaded or do I need an additive?
Donald Carmichael

[Peter Cresswell]

Hi Donald,
I think there is a good chance you can use unleaded without additives. The heads were aluminium so they will have had hardened valve seats anyway and in 1990 there is a good chance the engines had unleaded compatibility. You will probably have to use a good quality super unleaded, and if it pinks then you might need to use an octane booster as I think the Rover V8 needed 101 octane. Ethanol in the fuel is another issue and a 1990 engine and fuel system will not be ethanol compatible. anything rubber, or steel is likely to be a problem, so fuel lines and fuel pump diaphragms and if you are using carbs, the seals all need checking and changing.

[Donald Carmichael]

Thanks Peter. The conversion was in 1990 so the engine was probably older than that. I think that I will continue using an additive although the previous owner said it did not need one.
Donald

[David Heaton]

Hello Donald

I have a 1974 GT V8 (factory built) and I use normal petrol but add Millers VSPe Power Plus. This what Millers ay about it:

"VSPE POWER PLUS MULTISHOT
Description
An ALL IN ONE petrol fuel treatment providing ethanol protection, lead replacement and an octane improver dependent on selected fuel quality.
Application
Recommended for all classic engines previously requiring leaded fuel and now running on unleaded fuel. One bottle treats 500 litres, dilution 1 ml per litre. One full measure (50ml) using the multi-shot bottle treats one 50 ltr tank of petrol.
User Benefits
Endorced by the FBHVC A rating.
Octane enhancement of up to 2 octane numbers (20 points) dependent on fuel quality and combats the adverse effects of ethanol in fuel up to E10.
Prevents valve seat recession on engines with unhardened valve seats. Prevents detonation, hot spots and over run.
Prevents fuel system corrosion and helps protect components. The formulation is carburettor anti-icing and contains anti-oxidant to improve fuel life."

I have no connection with Millers but have used this for years and my car runs very well on it. The cost probably works out the same as using super unleaded but has added benefits.

Hope this helps

David

[Peter Cresswell]

This from the V8 Register:
http://www.v8register.net/subpages/V8NOTE216updated.htm There is a lot of information about V8 MGBs on this site.

This seems to suggest that all V8s built by Rover after 1970 are unleaded compatible. Since the SD1 was introduced in 1976 any SD1 engine should be unleaded compatible. However it is worth remembering few caveats:

1. The version in the MG GTV8 was a low compression engine (8.25:1) not the high compression (9.25:1) engines fitted to the Rover P5, P6 or SD1
2. Although the engine may have come out of an SD1 it may have been changed in a previous life for a pre 1970 one.
3. If it has come from one of the Rover saloon cars the use of Super Unleaded and possibly an Octane Booster should prevent detonation - much worse than pinking and a real engine destroyer.
4. Using a lead replacement additive is no guarantee to the life of the valves. I have used Castrol Valvemaster for 6 years and suffered valve recession last year after a steady 70 -75 mph on the French Autoroutes. I seem to remember reading that a speed cruise is not good!

[Peter Cresswell]

The engine 10A20783 is from a 1976 to 87 SD1 Manual with 9.35 Compression Ratio with carbs. Likely to need Super Unleaded these days and the later it is the more likely it is to have modern unleaded valve seats. A friend of mine who knows a fair bit about Rover V8s reckons the early cars had valve seat inserts made from piston ring cast iron, but this is much better than cylinder head cast iron, and they should run for many thousands of miles on unleaded without a problem. If the engine had come out of any Land Rover they all were capable of running on unleaded (unless of course someone had swapped the engine!).
See here for Rover V8 engine numbers: http://www.capriracing.co.uk/RoverV8EngineNumbers.htm

[Donald Carmichael]

Thank you all. It appears that the vendor was correct in telling me that it was ok to use unleaded.
Donald