warmfuzzies

Yes, BP 102 is around, but at £2.50/litre.....($20/gallon??) not for mere mortals like me, and to boot, it only shows gains with re-mapping, so not for me again then......

NineMeister

UK fuel octane rating is (RON+MON)/2, whereas US fuel is RON, thus a UK super unleaded 97(R+M)/2 fuel is roughly equivalent to a US Super 93RON.

We are lucky to have Shell Optimax 98 and BP Ultimate & Tesco 99 commonly available, which does explain some of the significant improvements that we have seen, but keep in mind that Porsche specify 98 Octane for the 964 & 993 in the handbook (and usually on the sticker inside the petrol flap), there's no "cheating" by using a better fuel than Porsche recommend!.

RON = Research Octane Number
MON = Motor Octane Number

SimonExtreme

Wow. So much written and so much sceptisim or wrong! So here I am, a bit of a newbie, about to upset some people! And it's not the pro tuners I am having a go at, either! Here are some facts.

I have seen various (964's) cars in different states of tune on the same RR on the same day. Here are some facts.

It is possible to get 308 bhp (ATW) from a 964RS without MOTEC. You need a well mapped chip, right exhaust and inlet mods and a good engine! I think Colin is fairly modest when he says his chip gets 295 bhp but mine (308) was done by somebody else.

I have also seen MOTEC at the same time and it does make the figures suggested.

And at the same time, I have seen standard cars make standard figures.

Now, I am lucky enough to know enough about RR's to know that the runs were consistant and weren't fiddled, although I have seen a tuner deliberately fiddling RR figures to make himself look good (nobody on here!!).

So, what is going on. Firstly, the limit without MOTEC is just over 300 bhp. The issue above that level is fueling. The limit is reached when the injectors run at 100% duty cycle and its pretty hard to get around that! Once you have reached that point no amount of MOTEC etc will give you any worthwhile extra power. OK, there may be a few gains somewhere in the curve due to the ability to get a "perfect" map, but its just not worth it.

Why can you get these gains. Well, as already said, Porsche map for safety, for reliabilty, for fuel consumption and all round drivablity. They need to worry about warranty, vastly differing fuels, average quality of maintainance etc. Now, I am not saying that my map is taking a great risk but if we say that it has a 1 in 500 chance of a problem (hypethetical number), me as an individual would say that's good odds. Somebody building 50,000 cars would say that's bad odds!

Now, there doesn't seem to be an easy way of managing larger injectors with the Motronic standard set up so the option easiest option is MOTEC. There are other ECU's that can do the job and if you can find a tuner ion your area who knows another ECU but not MOTEC, there is no reason not to go there. However, you need to trust the tuner because there is a lot of rubbish out there.

As for whether MOTEC is any good etc, comments like that make my blood boil. So many race teams use it and most WRC rally teams are using either that or GEMS. So why doesn't Bosch buy them? Because it is a very small specialist market that isn't worth their trouble. There are probably less MOTEC units (of all sorts) sold each year than any single Bosch system for any car. MOTEC is not "plug and play" and needs real skill to set up. Why would Bosch want to be in that market?

So, to sum up. 295-300bhp (ATW) is achievable without MOTEC and 325 is achievable with MOTEC, both without stripping the engine down at all. However, to achieve the best figures your engine needs to be in good nick as you cannot make a slik purse out of a Sow's ear! When you are talking about cars that are 15-16 years old, there are more Sow's ears out there than silk purses!!

So, why is there so much scepisism and is it reasonable. The answer is both yes and no! It is reasonable because there are so many cowboys out there who offer chips and other tuning parts that make little to no difference and therefore we should all be sceptical. However, fortunatley, there are true professionals out there and non professionals who know what they are talking about and they can achieve the results.

So, unless you have hard evidence, it seems pointless to post a "point of view". Tuning 964's isn't something new and even then, an engine is just an engine and obeys the laws of physics. Get more air in with a more optimised fuel charge, and you will get more power. There is no reward for a manufacturer to push the limits which leaves lots of room for tuners to exploit.

Red rooster

UK fuel octane rating is (RON+MON)/2, whereas US fuel is RON, thus a UK super unleaded 97(R+M)/2 fuel is roughly equivalent to a US Super 93RON.

We are lucky to have Shell Optimax 98 and BP Ultimate & Tesco 99 commonly available, which does explain some of the significant improvements that we have seen, but keep in mind that Porsche specify 98 Octane for the 964 & 993 in the handbook (and usually on the sticker inside the petrol flap), there's no "cheating" by using a better fuel than Porsche recommend!.

RON = Research Octane Number
MON = Motor Octane Number
----------------------------------------------------------------------------------
Colin,
I think you have that the wrong way round ? UK =RON , US =PON .
PON =RON + MON /2 .

My owners manual says the minimum fuel quality is 95 RON ,85 MON ,the only unleaded available in Europe, back in 1989 !
The 993 is 97 RON.

This is not an attack on you and I hope isnt seen as knitpicking !!!

All the very best

Geoff

Geoffrey

The octane rating for US fuel sold for use on the street is based on the R+M/2 formula. Racing fuels use a mix of formulas, some R+M/2, some MON. Of course, there are many more variables to fuel than octane such as the distillation rate and specific gravity.

I'm not sure I whould even comment about the 104 octane booster stuff. Best left on the shelf at Wal-Mart.

Red rooster

Simonextreme,
Coping with larger injectors is not an issue for Motronic mapping.
Bosch have no need to buy Motec ( an excellent system ) as they have fully directly mappable systems available through the Motorsport programme !

All the best

Geoff

KirkF

How about 10% ethanol blend gas? They have a higher octane, but I think you pay for it in power don't you?

Kirk

108.5dba-static

Very interesting read. However I got to believe that 300+ bhp is possible without major engine changes or additions. My C2 produces 280bhp (at 6,200 rpm) and all it has a K&N filter, Cup pipe, Cat-by pass (one from 9M) and a off the shelf Ruf Chip.The engine has 70K miles on it and has never been rebuilt. Petrol used was standard 95RON.

I am sure that custom mapping (done by someone like colin) and some Optimax would enable me to get very close 300bhp without MoTec. With Motec who knows, although I would love to find out.

Andy

Heirsh

I think so Kirk, but if you tune the engine for it maybe not... (ethanol requires a diff mixture than gas)

check this read. http://en.wikipedia.org/wiki/E85

TR6

Please bear with me since I freely admit to being the slowest to catch up, but this question is still unclear to me: Is my US spec 964 stock engine with stock chip already mapped to require USA 93 octance (R+M/2) or if I were to invest in "tweaking" it with remapping or a replacement chip, is there more power headroom left to gain while still burning US 93 octane fuel without pinging/knocking?

Geoffrey

Your stock 964 requires 91 octane (R+M/2) AND is in a conservative state of tune. eg not all 91 octane fuels have the same properties. There IS performance to be gained by using 93 octane AND remapping the ECU. The IS NOT performance to be gained by using 93 octane and the stock chip. eg, the ECU does not advance and optimize ignition timing for various fuels above 91 octane.

kgorman

Geoffrey,

Do you mean an off the shelf chip or do you mean a 'live remap'? Is there any benefit above 93 octane? What about 100 octane?

Geoffrey

I don't know anything about off the shelf chips without listing them, reading the tables, and testing on a dyno. Are there some good chips out there? Probably. Do I know which ones they are? NO. Obviously a live remap is the most reliable way to tune your particular engine. So my advice has always been that the easiest, most reliable way to "chip" your C2/4 is to buy a copy of a 964 Cup chip which will give you 10rwhp but require 93 octane.

"Is there any benefit above 93 octane?" - YES, 10rwhp via CUP chip

"What about 100 octane?" - YES, but why?

Marc Shaw

From where (legally)?

Marc

JasonAndreas

The only legal source would be from the owner of a cup car or the actual ECU. They are NLA from PMNA or PM in Germany. Technically selling third-party copies is just as legal as what any of the aftermarket chip suppliers are doing (i.e. its not). If you can locate one, my time is free (i've never charged anyone for duping originals) and I'll post the contents (maps, rev-limiter, everything).