e10,91,95,98 for d2 v8

[mate]

didn't want to hijack the other refueling post so started this one.

has anyone worked out what the d2 v8 motor runs best on? just thought i would ask

i see on the cap it says premium fuel only however my thought is back in the late 90's to early 2000's technology wasn't as refined as it is now so what was 98 octane back then could possibly compare to a good 95 these days..

i filled the tank up last week with 91 and reset the trip meter to be able to see how far i get on that octane. it is still going to be a while before i finish off the tank as i only travel 2.3km to work and back each day. what i was planning on doing is refueling when the gauge reads the same position as last time i refueled and throw in the same amount of fuel then reset the trip meter again each time and record the results for each octane to see which is the more economical.

but it will take forever and would like to know if anyone else has worked this out with other d2 owners and averaged the results out to get the answer?

[discorevy]

Don't think 98ron was widely available back then but 98is 98 and 95 is 95 Ron , (research octane number) . d2 v8s don't have high enough compression to take advantage of 98 in standard guise
Regarding measuring differences with gauge.... You wouldn't get even close to accurate
Cheers

[Eevo]

personally i find i get further on a tank of 98.
it may cost more, but i feel its worthwhile.

[CaptainJack]

ive done three tankfulls since aquiring my D2 V8 and decided right off the batt to work out if there is any differnce between 95 and 98

Both tanks have been similar routes - about 180 km a day back and forth to work, combination of a little city traffic and mostly highway diriving.

First tank was 95 ron and avg 16.3l/100
Second refill was on 98 ron, and came in at 16.2L/100
On my second refill i put 87 litres in - so not much 95 left in the tank to water the 98 down.

taking what could be traffic variables into account, i dont think theres any economy benefit to runnig 98

[PhilipA]

There is no way you will see an economy benefit % which exceeds the price difference % in a Low compression RV8 even with Motronic as it will be tuned to run on 91.

If you are lucky enough to have one of the last D2As with a High compression v8, you may see a benefit as the timing will be optimized for 98 and using 95 will knock back the advance, but it is doubtful that the % increase in economy will exceed the % difference in price.

An extremely dirty carboned up V8 will see a better increase, but probably an Italian tune up will do the same thing.

Regards Philip A

[Eevo]

If you are lucky enough to have one of the last D2As with a High compression v8, you may see a benefit as the timing will be optimized for 98 and using 95 will knock back the advance, but it is doubtful that the % increase in economy will exceed the % difference in price.

actually my D2 (not D2A), is a high compression v8.

[discorevy]

High compression v8 in d2 is relative, cars that can use the 98ron are usually running 11.5 or higher compression ratio, the knock sensors (piezo electric microphones)on d2 won't tell the ecu to advance the timing any further from 95ron to 98ron therefore any benefit is less than negligible, but if your happy paying the extra for the placebo effect then you won't do any damage

[Eevo]

that would be true if timing advance was the only thing 98 was good for.

[Tombie]

that would be true if timing advance was the only thing 98 was good for.

It is a scary day when I find myself in total agreement with you Eevo :cool:

[mate]

actually my D2 (not D2A), is a high compression v8.

Is there any way I can check if I have a high or low compression v8?

[pop058]

Is there any way I can check if I have a high or low compression v8?

Is it stamped near the engine number ??

[PhilipA]

Yes.

And re the CR using 98. The compression ratio where 98 is required depends on many things , including most importantly the combustion chamber shape.

In an RV8 the combustion chamber shape is 1961 high tech so needs a much higher octane at a given compression ratio than engines designed in say 2000s eg GM Gen IV which runs 10.5 to 11.2 :1 on 98.

The camshaft design and duration also affects this, as do the installation of knock sensors , and sequential injection.

But from the many posts on here complaining of excessive pinging over time, the 9.34:1 Vs 8.313:1 low comp, the 9.34:1 should use 98.

Although I must admit that LR compression ratios seem to be about as factual as Game of Thrones.
Regards Philip A

[Tombie]

You mean GOT isn't real?

[mate]

Yes.

And re the CR using 98. The compression ratio where 98 is required depends on many things , including most importantly the combustion chamber shape.

In an RV8 the combustion chamber shape is 1961 high tech so needs a much higher octane at a given compression ratio than engines designed in say 2000s eg GM Gen IV which runs 10.5 to 11.2 :1 on 98.

The camshaft design and duration also affects this, as do the installation of knock sensors , and sequential injection.

But from the many posts on here complaining of excessive pinging over time, the 9.34:1 Vs 8.313:1 low comp, the 9.34:1 should use 98.

Although I must admit that LR compression ratios seem to be about as factual as Game of Thrones.
Regards Philip A


Mine reads 9.35:1 and the other guy mentioned earlier that his reads 9.38:1 and now your saying there's a 9.34:1 how many high compression motors are there???

[PhilipA]

There is only one spec AFAIK.
I had a Google of Thor and the only reference I could find was 9.34.

Now you or the other poster may have read the last digit incorrectly so your two may be the same and my UK forum reference incorrect.

BUT do you realize how small a difference of 0.01 to one is?

It is maybe a tiny sliver of material, and in any case the chamber are cast so they are all over the place anyway and may vary by lots more than 0.01 to one, more like 0.1 to one.

Darn I knew there would be a bush lawyer somewhere who would quibble over 0.01 to one CR , so I looked it up over several sites including the RAVE page.

To find your actual CR to probably about 0.1 you will have to get a burette and measure the combustion chamber, calculate the thickness of the head gasket, and work out the volume from the bore ( and you will be wrong because the gasket may not come exactly to the bore), and somehow calculate the bowl volume including the area above the piston and down to the ring land.
I have had a go at it and obtained a result using Kero, a sheet of Perspex, and some plasticine but it was probably only accurate to about 0.5 or so.
Regards Philip A

[mate]

There is only one spec AFAIK.
I had a Google of Thor and the only reference I could find was 9.34.

Now you or the other poster may have read the last digit incorrectly so your two may be the same and my UK forum reference incorrect.

BUT do you realize how small a difference of 0.01 to one is?

It is maybe a tiny sliver of material, and in any case the chamber are cast so they are all over the place anyway and may vary by lots more than 0.01 to one, more like 0.1 to one.

Darn I knew there would be a bush lawyer somewhere who would quibble over 0.01 to one CR , so I looked it up over several sites including the RAVE page.

To find your actual CR to probably about 0.1 you will have to get a burette and measure the combustion chamber, calculate the thickness of the head gasket, and work out the volume from the bore ( and you will be wrong because the gasket may not come exactly to the bore), and somehow calculate the bowl volume including the area above the piston and down to the ring land.
I have had a go at it and obtained a result using Kero, a sheet of Perspex, and some plasticine but it was probably only accurate to about 0.5 or so.
Regards Philip A

Hahaha :) all good man im not having a go at ya I was just thinking well I dont know these engines and as unlikely as it sounds I had to ask how many varients there were in high cr

[Pedro_The_Swift]

one.;)

[ozscott]

Mine from new...last of the d2 before the d2a pinged like a mad thing on 91 when i had to use by necessity once. The fuel flap says 95 min and 98 recommended. Mine is a HC motor. It definitely runs better on 98. Dont forget too that 98 usually is a cleaner fuel and better for your engine. Mine has run 98 ron 99% of its life when im running on petrol. Most of the time she ran LPG so much cleaner again. None of this helps a situation where you never get your injectors serviced and a dribbling one takes out a pot by dribbling away and washing the (Penrite) oil off the bore. Still 260,000 is well under what these motors can do but also its always got me home and i dont spare the rod.

Cheers