3.5 to 3.9

[spannerboy]

whats the differences i.e ecu,air flow meter etc and what are the power gains?

[TVRleigh]

As far as I know its just the ECU. and the cc

[spannerboy]

thanks leigh,i have just bought a 3.9 engine and was just wondering what the benifits and differences were

[convert]

What compression ratio is the 3.9 you have?

[spannerboy]

not sure to be honest,what is the difference between the 3.9's,all i knowis it is a range rover classic engine so i'm guessing it#s the low compression one. what is the serpentine engine is it the high comp one?

[pwd95]

It'l probably benefit from a new hotter cam & a webber 500 carb.

[TVRleigh]

I think the clasic range rover had about 9 - 9.5/1 CR.

It could do with a better cam, and a re-maped ECU. then your get about 210-240 BHP.

[Wedg1e]

9.35:1 was the standard for a 3.9 (ie 3948cc).

The ECU on a flap injection system is non-mappable; it can be fine-tuned to some degree but usually an improvement in one area is offset by some degradation elsewhere.
Doesn't apply to a hotwire of course, which CAN be remapped.

[mr-scott]

spannerboy said:

not sure to be honest,what is the difference between the 3.9's,all i knowis it is a range rover classic engine so i'm guessing it#s the low compression one. what is the serpentine engine is it the high comp one?

On the Rover V8 3.9 if you look for the engine number (next to where the dipstick goes onto the block) above the engine number it is stamped with what compression ratio your engine is - simple as that!

[spannerboy]

thanks for the replies guys,so in essence is it worth putting it in a 350 if it is a low compression engine and does the 3.9 ecu plug straight in?

[TVRleigh]

If its a flapper system then it should just plug it, you need to use all you existing EFI set-up inc AFM, injectors Etc.

If it hot wire it may need a matching or re-maped ECU.

[spannerboy]

sorry leigh educate me here,how can i tell the difference?

[TVRleigh]

what does your AFM look like, and Does it have any numbers on it.

Do you have a resister pack next to the AFM.

[spannerboy]

it is the standard silver box with the corrugated top

[TVRleigh]

If it looks like


then its a flapper.

[spannerboy]

yes it looks like that,wish my engine bay looked like yours though

[TVRleigh]

Took a lot of work. plus kept the car of the road too long as ran out of time 1/2 way, so had to get put on hold.

Does the 3.9 your getting come with the EFI, if so you can fit the ECU and AFM that comes with it. it will be a hot wire if its a LR 3.9 and will look like



If not you can use your existing EFI set-up, but you will have to fit your Injectors and Plemum, as the new one has a stepper motor, but yours has a overrun valve.

[gwood]

TVRleigh said:

If it looks like


then its a flapper.

looks really good under there, please could you tell me where did you get the water hoses,i have been looking for some but never found any

[TVRleigh]

All the water hose is Samco from demon tweeks,
But ACT do kits.
I got mine before they did kits, so had to do me by trial and error, and ended having to buy a lot of stuff I could not use.

you may want to use stainless clips. but can work out expenise at £2-£4 each.

I fitted braided oil cooler hoses also, plus fitting a Twin fan Ali rad this weekend. and a carbon dash.

Pic of the other side.

[eesbad]

spannerboy said:

is it worth putting it in a 350 if it is a low compression engine

The 3.9 Rangey engine was only putting out 180 bhp, so you'd be down on the 350i Vitesse engine by 10-17 bhp to start with... But the potential is there - it just needs a few mods first!