Supercharging RV8 flapper

[V8 Fettler]

I have a Range Rover Classic 3.5 EFi with flapper and Sprintex supercharger. The previous owner told me that it had never run with the supercharger. There is life in the old thing, but I'm confused re: engine breathers. The pipes are run into the plenum/throttle body similar to an NA car, my understanding is that this causes problems with breathing.

I'll get to the point (please!): where do the engine breather pipes for supercharged RV8 Wedges run to? Oil catch can? Atmosphere side of supercharger?

[V8 Fettler]

2 adjustable pots on the outside of the ECU, although how these operate in conjunction with the mixture adjustment on the AFM I'm not certain.

[V8 Fettler]

Thanks Adam, been a long slog with this.

Have re-jigged to something like your arrangement, engine runs but issues with CO or HC for MOT.

Could you please check the pipes marked on your photo.

Yellow (atmospheric) goes to a solid pipe that runs under the plenum but no connection to the plenum, then onto the idle air valve.

Red (atmospheric) appears to go to your flame trap on the passenger side rocker box cover?

Just out of view on the edited photo below (white arrow) is the other side of the idle air valve, connects to the vacuum side of the throttle body?

The engine breather circuit on mine doesn't appear to be complete: flame trap on the pass side rocker cover, pipe now leading to atmospheric side of throttle body, but no visible breather on the driver's side rocker box cover. Do you have a breather on the driver's side rocker cover?

[V8 Fettler]

Thanks Adam, poor description on my part, extra air valve for use when starting from cold.

Pipe marked white is the other side of the extra air valve to vacuum side of throttle body?



3.5% CO but 2000HC and climbing, can trade lower HC for higher CO.

Edit: I'll recheck, but I can't find any breather on the driver's side rocker box cover, there is a breather on both rocker box covers on my flapper TVR.

[V8 Fettler]

Thanks Adam. Oil is fresh, compression unknown but no blue exhaust smoke, heavy breathing or clanking noises. Idle is about 750rpm, will increase to 1100. Was your CO checked at 1100 and HC checked at 2000?

I'll need to create a breather for the driver's side rocker box cover. The oil filler is fitted on that side so might be able to do something with that. Any thoughts on the diameter of hole required?

[V8 Fettler]

Thanks AdamOZ2, does your oil filler cap have a breather?

[V8 Fettler]

Ta, RR is an auto hence idle speed 750 to 850

Edit: but you have the OEM breather fitted to the driver's side rocker box cover to allow air to be drawn into the engine and then out via the throttle body?

[V8 Fettler]

Thanks AdamOz, my engine doesn't have the protruding tube with the 0.5mm hole (that is small!), your engine has a breather circuit, mine doesn't.

I'll look at modifying the filler cap to accept a breather. Failing that, it will be off with the rocker cover and out with the drill.

[V8 Fettler]

Thanks for the offer Adam, but I just want it finished, it's been a "challenge" in many ways. Previous owner installed engine and supercharger but vehicle never ran in that configuration. Should be able to increase idle speed when on MOT ramp

[V8 Fettler]

Thanks for all the replies, I used a combination of British Standard Pipe thread fittings screwed into the oil filler to complete the breather circuit, I thought of drilling the cap but didn't think laterally enough for the "tape sponge to it" as a filter. Will revisit at some stage.

RR was bought as a non-runner. To my (almost certain) knowledge, it has never run with this engine, not certain if the engine has ever run with the supercharger, not certain if the EFi has been fettled for use with a supercharger. Now passed MOT using the ECU from the TVR, but engine not happy above 2k rpm so more work needed.

[V8 Fettler]

adam quantrill said:

Yeah I wouldn't push it then - it's probably running too lean with a stock 4CU and you could end up melting a hole in a piston when the revs rise.

You might need an ECU with adjustable "map" - these commonly have a knob on the side and a piggyback circuit inside.

Also quite possibly higher flow injectors, and adjustable FPR and a fuel pump that won't peter out at max revs leading to fuel pressure drop and running too lean.

Good progress so far though!

I would start by getting a wideband lambda on there and observing the AFR while you drive it about. It will be much cheaper than a rolling road session to start with.

Rangie had an adjustable ECU fitted, but even on leanest settings the emissions were too high. Fitted the ECU from a flapper TVR that happens to lurk in the lock-up and emissions OK for MOT (important milestone that). Following extended fettling, including adjusting the spring in the AFM ... run away!! , emissions now OK with adjustable ECU, also doesn't lean off at 3k rpm when stationary. I have acquired a wideband AFR sensor and clever box for £100, no gauge though (couldn't face spending £150), will rig something up to read voltage output (who said skinflint?)

I have a self-imposed rev limit of 2k rpm at the moment, will try 3k rpm when out and about tomorrow. Injectors are currently an unknown, as are so many things.

Mature Rangies that have been resting for a while are wonderful things but the pain to wallet is exceptional, at least TVR rust is restricted to the chassis and can generally be seen at a glance.

[V8 Fettler]

mrzigazaga said:

Hi mate...Was the supercharger originally fitted to this engine and removed or NEVER fitted..I only ask as if it was bought as an aftermarket install then you would need to change the head gaskets..In fact i would change All gaskets and water hoses/Clips ..Possibly lower compression to eliminate or lessen the chances of detonation..Use different temperature plugs?...Have good crank seals..A good clutch, UJ'S..Prop..Brakes..And then i think you might need a larger boost diaphragm on the dizzy?...And finally a slightly modified ECU..

I learnt that supercharging an engine is not a cheap project..Yeah you can bolt it on and hope for the best...Mmmm...The "Best" way to destroy an engine in seconds more like!...I wouldn't risk putting a blower on a worn engine..Any weaknesses and it WILL find it!..I had a totally rebuilt engine which had all the seals, Bearings ..Pistons and rings changed..The compression was lowered slightly but still the engine got trashed by a ring sticking to a cylinder due to heat build up..Cooling of the water system was inadequate which then caused valve problems.

Personally....I wouldn't drive it until all of the issues were addressed...

Thanks Zig, RR has several unknowns. Was built as a flapper EFi but current engine was - apparently - built as a carb engine, so lower compression ratio (although who knows what's happened during the intervening years). Car arrived in my ownership with S/C fitted, but had never ran in that configuration, as I understand it.

BHP is probably not much more than a flapper EFi, so brakes etc should be OK.

I don't intend to thrash the thing, 4k rpm max will be fine (not thrash it? That will be a first!) general trundling will also be fine, which begs the question "Why buy an S/C RR for trundling?", but that's not the point