3.5 high or low comp?

[fonfe]

If I remember correctly the 3.5 range rover classic came out with a high compression engine and a low,
How do you know which is which?
what is the CR of both ?

Thanks :)

[djam1]

The pollution engines were 8.13:1
The high compression engine was 9.35:1

Some of the early pre pollution engines were some where between the 2

The Rover Saloon had 10.25 or 10.5 : 1

Have a look at this it might help you http://www.roversd1.nl/sd1web/ (http://www.roversd1.nl/sd1web/basictuning.html)

[bee utey]

CR is generally stamped next to the engine number, by the dip stick. I have a 9.35:1 engine out of a 3500 saloon in the ol RR ute.

[101RRS]

I have a 9.35:1 engine out of a 3500 saloon in the ol RR ute.

I assume you mainly run it on gas but what is the min octane petrol you can run in it and at what timing.

Cheers

Garry

[bee utey]

I assume you mainly run it on gas but what is the min octane petrol you can run in it and at what timing.

Cheers

Garry

I don't use it enough to put petrol in it but it runs well on gas at 10 degrees BTDC just like the old P76 9:1 engines did. To run petrol over 9:1 I would get a dual curve ignition* or a manual (eg choke cable) distributor adjuster set with limits at 5 and 10 degrees.

*https://docs.google.com/viewer?a=v&q=cache:gs7vwpJO-eoJ:www.dualcurve.com/pdf/8795_frm15995.pdf+&hl=en&gl=au&pid=bl&srcid=ADGEESgacZixAtG2raWe3rjyxBv6AnHpmkMeZPrEOZ6x tQqX5FAyNp62csPLLl3EJsOgr6WcYe-OxA7aBhiEPWPEdmBxKpdF66VHl2eT3NGQANl5X5IMIcCQJ3tCZ I6XhqbXPREGGVLU&sig=AHIEtbQI336vby_1T2U3sEfvKG1bFUeSyQ

[101RRS]

Ok thanks - seems a bit complicated - I will stay with lower compression then for my engine rebuild.

Cheers

Garry

[fonfe]

Ok next question:
How much boost can you safely run on the low cr engine?
What's the biggest weak point in the engine? The rods?

[jakeslouw]

The weak point is the block and the crank caps AFAIK. That's why the 4.0 onwards engines were side bolted caps.

The con-rods and crank itself shouldn't have a problem with turbo and mild boost to about 8PSI (half a bar).

But a supercharger would be a better idea.

[loanrangie]

If I remember correctly the 3.5 range rover classic came out with a high compression engine and a low,
How do you know which is which?
what is the CR of both ?

Thanks :)

RRC were all low comp up to 83 when the auto was introduced and up to 85 in carby version just before the EFI came out. The 9.35's run fine on 91/93 RON and good on lpg- better than the low comps at least.