Petroleum already is bio fuel. It's just really well aged. Using valuable farm land to grow a crop to make fuel like we're doing here in the USA is beyond dumb. There have been studies showing it actually is a backwards step when you factor everything in that's required to produce the fuel. We'll find something eventually but burning down the Amazon rain forest in Brazil to grow sugar cane to make ethanol so that you can drive your car doesn't seem like a good idea to me.

Bob S.

 

Not sure the relevance of "bio", but yes existing petrol is. But I don't care if it's bio or non-bio (say someone invented a chemical synthesis process). I care whether it's OK to burn in my STR. AFAIK (and to a fair extent I don't!), ethanol is a different molecule with different burning and other properties than the mix of molecules in petrol.

You may or may not be right about land. A tough, complicated issue. Regardless we need to get the planet's biosphere in a better balance or it will do something that may not suit human life.

 

OK, I'll buy that.

Although I don't know of anyone that's tried E85 in their Jag, I do know first hand of several people that have inadvertently fueled other cars with it. Our national Corvette club had a road tour pull into a station that sold E85 and several cars unwittingly filled up with it. Suffice to say that they didn't get too far. Putting aside the long term effect on component deterioration, the fuel management system whether EFI or carburetor cannot cope with the vastly different characteristics of E85 without major modifications.

If a person were to fuel their car with diesel, there would be no surprise if it didn't run properly, why would there be a surprise with E85? Neither diesel nor E85 is 'gasoline' or 'petrol', where's the mystery?

 

Actually there is only minor modifications needed to run E85. That's why so many American cars are Flex-Fuel. The sensors automatically detect what fuel or mixture of fuel is going to the engine and adjust for that. So it would have been pretty easy for Jaguar to add this when the car was built. Especially when Ford still owned them. Ford has many Flex-Fuel cars on the road and it is common.
For us to do it after the fact may require too many modifications and changes to the cars programming.
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The STR will pull back the timing and fuel on midgrade gasoline under high-mid to heavy acceleration too. At approx. 5000 rpm while under a load, the compression ratio is approaching 11:1. At 6200 it's higher. Worse on days when outside temperatures exceeds 80 degrees. 91 octane or better is not only what Jag strongly suggests, you'll certainly notice the loss of power and potential damage to your engine if you don't adhere to the reality of detonation.

 

Why would there be detonation if the timing is retarded enough to prevent it? What engine damage?

 

Simple: Though provided with is a nock sensor, causing a pull back in timing, a supercharged engine can still undergo pre-detonation while operating at high engine temperatures and boost. Nuff said! Ask around...they'll tell ya.

 

This would be true for a Top Fuel drag car, not a mildly supercharged R. Let's not make the car out to be something it's not.

 

You guys are still arguing about this?

Well this weekend I had the perfect opportunity to test this out as I flew into Atlanta to pick up my new car and drive it back to NJ. But I just completely forgot about trying this out and I started this thread!

So I gobbled up 4 tanks of premium instead. The fuel economy meter "says" I got 21.6 mpg but I haven't done the calculations yet. I'm dubious about what it's telling me.

I should have run this one by the Jag tech guys who were at that 2011 MY introduction I went to at the Monticello Motor Club a couple of weeks ago. That's a bit different engine now. It's 5L with direct injection and they're producing the same kind of HP with no supercharging now.

Bob S.

 

I bought an 04 STR with 26.000kms on it (real!) two weeks ago.

I believe that the manual said 95 RON as recommended, which in Spain is the "regular" petrol. The "special" is 98 RON which is the one that the previous owner apparently used (or so he told me).

Which one should I use?

Another question:
If on "P" and engine at normal running temperature I accelerate to approx 3000 a few times (like 1 each 2-3 seconds) on deceleration I hear like some small "explosions" like if unburned petrol were ingniting. Is like when race cars make "reductions" (some times with flames on the exaust pipes, the STR without obviously ).

Is that "normal"?

Many thanks, and I hope to learn a lot about this car from this forum!

Jorge
'04 Stype R - '91 Porsche 964 - '99 Stype 3.0 - '59 Mercedes 220 - '02 Suzuki Wagon R+ 1.0

 

95RON is roughly equivalent to 91AKI which is what N.Am S-types are tuned for. 98RON is equivalent to 93-93AKI. No need for it.

The exhaust popping is normal.

 

I've noticed a difference in using 91 vs 93 octaine. As a result of this, I only use 93. Costs more out of pocket initially, but ultimately, costs less in experience.

 

What difference have you noticed, specifically.

 

I do not have the technical means to quantify it, but I will say this. My travelling is about the same each day. On 91 oct, I'd fill up on Sunday evening and last till about Wednesday evening. When filling up on 93, I'd fill up on Sunday and wouldn't be required to fill up again until Thursday evening.

It's like the 93 OC burns more efficiently in the STR than the 91 so it lasts longer. Most travels for me include a colleague or two and those who travel with me noticed also that I began fueling a whole day later. (Looking at the prices we pay for fuel draws that whole issue to everyone's attention.

 

Wow necro thread! I always use 93, will be using 93 with a 50/50 water meth mix soon to add a few points of octane since I like to remain sprited with the right foot in the heat

 

If you can't agree, then to each their own. Do what you believe to be fact, and accept the consequences as such, albeit good or bad.

 

Welcome to the forum!

That's scarily low mileage.

95RON is what is specified here and likely the rest of the EU. No need for 98.

What you describe on deceleration should not happen. Please start a new thread and let's explore it.

 

Unfortunately, this topic is bound to come up over and over much like the K&N filter and synthetic oil (equally) thrashed horses.

I congratulate Jorge from Spain for searching the archives for info rather than starting a new thrash.

 

Gas prices are dropping quite a lot in this area recently. Premium is wayyyy down to $4.01 (was ~$4.50) and regular is $3.81. Since I was next door to that gas station, I dropped in 5 + gallons of regular. I usually don't do that, but since I had almost 3/4 tank of premium in it, thought I'd try it. The weather has been cool and overcast this past week...temps in the upper 60's and mid 70's..so off I went.