Anyone got any good / bad stories about octane booster usage? In the UK I can get 97 octane fuel, but wondered if it would be worth boosting this to 99-ish using Nulon or Millers. Would it make a big difference, or are the European turbo motors optimised for 98-ish octane?

Hi guys

OK, here goes. Being from the "third world of South Africa" where we only get 97 leaded and 93 unleaded, I have found Nulon to work best. It is actually amazing what it does to the performance of the T4. Unfortunately it is not available here anymore, and my "Volvo" contact has advised me that a person should not use Octane boosters as some of these "melt" the plastic petrol tanks and pipes and parts in the engine. Hence, with my new T4, I have and will not add any aditives. I now have a SLOW T4 and have to live with it.

By the way, another friend of mine says, that 20% Toluene added to fuel also gives a great boost, and is Cat friendly. Like I said, I don't want to find out if its any good or bad.

Hope this helps

Regards

Michél

(Darkest Africa) Only joking, there is light yet!

Yup. Toluene is used in unleaded fuel here in europe as an anti-knock or TEL-replacement substance.

There was a big problem here in europe when they first introduced unleaded because it turned out that some types of plastic fuel tanks in cars which used to use leaded fuel were porous to the toluene and benzene compounds

There was a high level of these (carcinogenic) compounds getting into the passenger cabin.. Not nice :-(

But that's no longer a problem now.

Bye, Arno.

Can't tell you if they work or not as I haven't used them, but up to the 2.0T you should be fine with 95RON octane. The T4 likes to be fed 98RON octane for peak performance. A 2.0T should never need more than 98RON octane though.

If you really push A T4 (eg. screaming along the autobahn) at constant high boost levels (0.8 to 1.0bar or higher when chipped/tuned) for extended periods then it could use a few more octane points as the ECU will start to reduce the boost level after a while (to about 0.6/0.7 bar) as it detects some light pinging, especially during hot summer days.

I have been wondering myself if adding some octane booster would help, or if I should get some 'real' 100+RON octane race-fuel (expensive though!)

Bye, Arno.

Could you tell me where it's fitted? I've had a look on the manifold but there doesn't seem to be any plugs or anything to tap into. I'd be interested in fitting one myself.

Yup. I have a boost gague. Mounted it below the radio (removed the storage box) in a DIN-sized cutout.

Less than optimal for good visibility (mounted pretty low, so odd viewing angle ruins the exact readout), but it's about the only spot I could find where I could mount one. No A-pillar pods for the S/V40's yet AFAIK.

But still very useful to me. It's fun to feel how (on my T4) it's pretty gentle as long as you keep the boost to about 0.5 bar, but once you get over that and the revs climb to 3500/4000rpm then all hell breaks loose and the monster comes out.. :-)

To install you have to remove the tube going from the throttle housing to the fuel pressure regulator and insert a 'T' piece. Then run a tube from there to the driver's side (passenger side has all the ventilation stuff under the dash, which makes access difficult). There's a rubber insert in the firewall (may be hidden behind sound-deadening material, but which has a pre-cut opening) which you can use to feed the tube through.

Unless you have an electronic gague, then you just hook up the pressure sensor to the 'T' piece and run a few wires to the inside.

On my car the tubes on the throttle housing were secured using 'clamp-on' hose clamps, which I replaced with regular (small) 'screw on' types.

Hope this helps..

Bye, Arno.

Thanks for that, I know the hose you mean. I'll have a look at what gauges are available ... I've often thought it's a bit irritating that we don't have them as standard ... I know that Saab gauges aren't very accurate but it would be fun to know what the boost pressure's doing from time to time, and how different conditions affect boost.

VDO is a prime candidate of course, but brands like APEXi, Blitz and a few more should all have gagues (mechanical or electronical).

Bye, Arno.

I suppose I'm interested to see if the ECU will respond to and optimise the motor for higher than 98 octane, or if it will make no difference.

With the 2.0T I've experimented with 98 and 95 octane ... after running 3-4 tanks of 98 the car feels a little quicker to pick-up, and using a stopwatch I can get 4th gear acceleration from 40-60mph to be consistently 0.2 - 0.3 seconds quicker than with 95. In other words, about 4% improvement in acceleration for an 8% extra cost per litre. Worth it when the company's paying for the petrol :-)

Nulon is made in Denmark, I would have thought they have a distie in Sverige. I've seen an "independent" test done in an Australian mag where Nulon gave best results in an octane engine against STP, Wynn's, 104+ and Millers', with an increase of 4.7 RON over the base 97 octane. The product is Pro Strength Octane Booster, website www.nulon.dk. Might be worth a try!

The problem is not to get you car to run optimally, but to keep it in that

mode.

A brand new engine needs no octane boosters. Then after it ages and gets

crapped up inside, it's octane requirement increases... Adding octane

boosters is like a fix for an addict. And, naturally, since such products

are intended to boost octane with little/no regard for long-term engine

cleanliness (nor the health of those who come in contact with it), your

engine will quickly become addicted to the octane booster, often to the

point that using it no longer produces any benefit but failure to use it

will result in degraded performance.

I've been down that road...

FAR better to keep your engine new-like clean and its octane requirement

new-like low.

The one product that can do this for my engine is DurAlt Fuel Conditioner.

Among its many talents is the ability to let '60s-era muscle cars that

'require' leaded high-octane gasoline to run safely and well on modern

unleaded fuel.

What matters is the difference between a fuel's octane and an engine's

requirement. Keeping the requirement minimized and the engine cleaner

is the way to go, for multiple reasons...

- Dave; '95 854T, 110K mi