Fuel additive recommendation

[Kansas]

Highest grade of fuel we have around here is 91. Can anyone recommend a good fuel additive or octane booster for my 993?

[Dmitry at Pelican Parts]

Hello - take a look at the link below to a great additive that Liqui Moly makes. Please let us know if you have any other questions.

https://www.pelicanparts.com/catalog/shopcart/CARE/POR_CARE_LIQUI1_pg15.htm

[EMBPilot]

Techron available locally is also very popular option for 993

[Nine9six]

Originally Posted by EMBPilot

Techron available locally is also very popular option for 993

I believe Techron to be a fuel additive that cleans engine deposits and not so much (at all) an octane booster.

[914986]

I'd suggest Torco, Lucas, or 104+ octane booster (in that order), as it you can probably find one of those locally.

[997991992]

torco works well

[ChrisHart]

Originally Posted by Kansas

Highest grade of fuel we have around here is 91. Can anyone recommend a good fuel additive or octane booster for my 993?

Hi, I often wonder how owners can state that their cars produce, say, 272HP or 285 HP if they are only using 91 octane fuel? Surely these figures are predicated on the car being driven with 98 octane, or would that mean our Australian/English cars produce more power, or conversely , USA vehicles produce less?

[nickd]

Octane ratings use a different calculation in US vs RoW. Germany’s 98 equals US 93. Similarly, RoW 95 equals US 91. 993 calls for RoW 95, so US 91 is just fine. If you have a very hot track day planned, then dump in some octane booster (better yet, use the track fuel pump).

[Mahler9th]

Octane boosters are a complete waste of money for stock 964 and 993 cars.

[ian c2]

I’ve used them as a cleaner in the past .
Worked especially well on a supercharged Range Rover .
No noticeable performance gain whilst in the tank , but ran MUCH better on the following tank and thereafter for the next few 000 miles .

I’ve never tried them on a 64 or 93 , but suspect Better performance will be had by disconnecting the battery for 30 minutes ...

I was just thinking today about adding one to my tank , before it first fires after 7 years idle .
But I allready have a dedicated cleaner in the tank as a flush .
I was thinking I’ll let it fire in the garage , then once I know it will start push it onto my inclined driveway to smoke the neighbors out instead of smoking my garage out

[KNS]

Originally Posted by Mahler9th

Octane boosters are a complete waste of money for stock 964 and 993 cars.

If you can only get 91 gasoline (rather than 93) and you live in the desert Southwest, you need to bump up your octane to match 93 for summer driving (or go easy on the throttle). Steve Weiner will tell you the same thing. Driving my 993 along side a high wall and with the window open, I could hear the “Clackity, clackity” of detonation under hard accerleration. This was while I was living in Phoenix and on a hot day with 91 pump gas.

Had I not had the window down and the wall next to me I wouldn’t have heard it. The car is stock. Same goes for climbing a long incline or mountain pass on a hot day. These cars were designed for 93 but you can’t get that in every state.

[Mike964_61]

Try Torco fuels website, the sell race additives that will give you the bump you need. Not cheap, but def cheaper than a new motor.

[Amethyst]

I use Archoil AR6200 fuel treatment on my stock 964/993. I use it to counteract the harmful effects of ethanol to the fuel system. The advertising claims it combats knocking/pinging and improves gasoline's resistance to pre-ignition. I believe that is what all the competing products claim as well. You will have to decide which one you want to believe. I don't hear any knocking/pinging from the engine during the hot summer drives. https://www.archoil.com/products/ar6200-fuel-treatment

[Mahler9th]

What is the purpose of octane booster for this application? As all of you likely know, these engines use DME and that comes along with knock sensing and subsequent dynamic changes. So it is an adaptive system.

There are of course design limits, and I am sure PAG would say, for example in a warranty situation, that if you used fuel with an octane rating of 70 R+M/2 and they specified a minimum of 91, then you might be denied a claim if there was some kind of engine problem or damage.

I am pretty sure that there are error bars in the government's regs related to stated octane numbers, and undoubtedly PAG factored these in (with headroom) when the DME systems were designed back in the 90's.

I owned a 993 for a few years here in CA, and I think when I had the car all you could get was 91 r+m/2 (with whatever error bars existed at the time).

The car could deal with it. I never tracked the car, but if I recall correctly it was not common to worry about 91 in track use with these cars when they were active in track events.

There are always "corner cases" with these things. I can envision intake air temperature and fuel quality/consistency in places like the desert SW and high loads could push the system beyond its adaptive range. But in those cases I would worry more about thermal stresses on cylinder heads than knock (I have cracked a couple of 993 heads in high ambient temp racing conditions-- I would hate to have that happen on a street car).

But I don't think it makes sense to use a booster if the system is stock and the fuel is in the legal part of the quality curve in most places. That assumes of course that the rating system and general fuel composition today is close to what it was when the cars were designed.

If I had a stock car and I had issues with knock because of the fuel available in my area, I would try to come up with a different solution than octane booster.

[996AE]

Based on Steve Wiener. recommendations I went with lower US Spec 3.2 Mahle P&Cs over the Euro highrer compression on my recent build. I really wanted to go 10 3 1 euro but without twin plug or 95 min octane no joy.

In speaking with Steve Wong he comfirmed same thing. His chip would have to detune the Euro spec for CA 91 octane eliminating he higher compression.

Went with US spec, test pipe and Steve Wong chip.

Stoked

[sandiego]

I talked to VP at Rennsport about using their octane booster to avoid paying $10/gal. at the track. They said don't do it for a track car.