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Discussion Starter · #1 ·
Hey, does anybody know what the BHP is for a stock 1.6 SE mk4 golf is? or even better, know where i can find a rolling road graph for one? And another random question for the brainiacs out there! By paying more for say shell optimax or something simular i know it's more responsive and slightly more powerful but would i get better MPG and if so would it be enough to make up for the price difference between normal unleaded and optimax? If that didnt make any sense let me know! Cheers guys. peace
 

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Shroomo, you already know, it says on the left hand side underneath your name 105ps!

Optimax will probably make no difference what-so-ever. Get the normal shell stuff, something like that would probably be best.

Optimax might be slightly more refined but you are unlikely to see any difference to performance or economy and it definitely wouldn't make up the difference in price.

Optimax is 98 RON (Research Octane Number) Which means it combusts at a higher temperature than 95 RON.

Fuel with a higher octane rating is recommended for cars where either the compression ratio is high (over about 10.5:1) or for forced induction cars. Even most turbo charged cars are designed to run on 95 RON these days as it's more readily available.

Not sure about the mk 5 Golf Gti, that has a high compression ratio and is turbo charged so I personally would use optimax whether it says to or not in the handbook. Other examples include Civic Type R, my last car Smart Roadster (this had a relatively high compression ratio and high turbo boost pressure so it was essential).

The reason for requiring the higher octane fuel is to avoid detonation (also known as pre-ignition, or pinking). This is where the fuel heats up too much (beyond its flash point) and ignites before it is supposed to. i.e. before there is a spark at the spark plug. This has the effect of trying to push the piston back down when it's supposed to be on it's way up. Obviously this can damage a lot of engine internals. It gives a sort of knocking sound.

Modern engines also have knock sensors which listen for a knock and retard the igniton, however this only works to a certain extent.

Some highly tuned cars turbo charged cars use water injection to cool things down as well as octane boosters to avoid detonation.

I know I tried optimax in my MG ZS 180, i thought i had a case as it was quite a powerful engine but it made no noticable difference to performance or fuel economy in my experience. In the Smart Roadster it definitely did, the 98 RON was necessary.

What ever you do, do not buy BP super unleaded, it is only 97 RON and about 5 pence more per litre than optimax. Apparently Tesco have brought out a 99 RON now but never tried that as changed the Smart Roadster for my Diesel Golf!

Sorry to waffle on but those are my thoughts on high octane fuels. Anyone agree / disagree.

Nick
 

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Fuel with a higher octane rating is recommended for cars where either the compression ratio is high (over about 10.5:1)
11.5:1 on the 1.6 16V (105bhp) - mine doesn't drink anything but Optimax and it definitely runs smoother and pulls better. The fuel cap does state 95-98 RON and for the first year I knew nothing about cars so just fed it the cheapest stuff.

internals. It gives a sort of knocking sound.
That knocking sound happens a lot on the 1.6 16V on 95 RON, doesn't happen with Optimax unless I do something silly like using too high a gear at too low a speed or don't have enough revs for the load.
 

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1.6 8v = 100
1.6 16v = 105

I am un-educated when it comes the technical side of High Octane vs Standard fuel but thanks NickG for stating some of the facts. I always use Optimax for no other reason that I think it is healthier for my car. Have never noticed a great difference in performane or fuel consumption but am happy to pay the little extra if its doing my car good.
 

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Oh sorry, I wasn't aware that the 1.6 would have such a high CR. Is that not only on the FSI?

They must have done that to improve the efficiency and bottom end torque. Quite right, I personally would use optimax in an engine like that. I have seen the catastrophic effects detonation can cause and don't want it to happen to any of my cars!

If you believe what they tell you optimax must be slightly better for any cars health, it may cause less wear on things like valve stems, seats, cylinder bores etc, and if it makes you feel better who can argue with that.

Having said that, I still think you'd be hard pushed to tell the difference, even over a great amount of miles.

I wonder how many owners are aware of what their cars should run on? I often see cars filling up on 95RON and think, they shouldn't be putting that fuel in there.

The stealer didn't tell me when I bought my Smart Roadster it was 98RON minimum, and I know they didn't put it in when I took the car in for repair etc as there wasn't a garage that sold Optimax or even a BP for miles around!

Nick
 

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hi i agree that optimax and higher ron does make the 1.6 run better and smoother and i always been filling up with either 97 or 98 ron!

i also read from somewhere that if you run a 1.6 on 95 ron it will gradually burn your valves out! but am not totally sure on that.

but i guess theres no harm paying the extra ?? if it does help the engine

will
 

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Oh sorry, I wasn't aware that the 1.6 would have such a high CR. Is that not only on the FSI?
I don't know about the FSI, I think that was only made in very limited numbers on the MkIV - don't think I've even seen a MkIV FSI in the UK but I've certainly read a review of it and the car was clearly a MkIV, the review said it lacked refinement but the technology defo worked.

The non-FSI 1.6 16V MkIVs are definitely 11.5:1, I've got the spec sheet at home, and besides, the knocking sound with 95 RON happens so much it's not funny.
 

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i've got a 1.6 8v and i run it on BP ultimate (no shell round here)

i do prefer it to normal petrol however i get terrible economy whatever fuel i use...must be the way i drive
 

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Discussion Starter · #13 ·
Cheers everyone, i didn't expect such a response! When i had my VW camper i was a member of several forums and everyone there was really helpful. It just prooves that VeeDub lovers are the best people in the world! Maybee together we can rid the world of nova's and pug 106's! [6] Take care! Kris
 

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As has already been said, 8valve's have 100 bhp and 16 valve's have 105 bhp. In my experience the 8 valve feels slightly quicker as the peak torque is reached at a lower r.p.m and also it seems to revs free-er ( if there is such a word ).

Also when i filled up last week i used optimax and it felt much quicker. This week i filled up with 'normal' unleaded and it seems a little different. Economy is not brilliant on either.

They can be made to go quicker by fitting a chip that Oetinger do, when i ordered my car from Germany in 1999 they offered it to me, but my insurance company was already confused that i was insisting my car was a Trendline and not an S spec so i declined the offer !
 

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I've looked at the Oettinger offering, it's not cheap [:|] Similar gains for much less ??? from Custom Code and Revo. Of course I can't really compare them in depth. Would you believe you can get a Schrick performance cam for the 1.6 16V, that's nuts (and I think the Oettinger package includes a cam if I remember right).
 
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