I got a 93 wrx and run it on BP Ultimate with no octane booster.

I've been reading around about 97ron fuel and optimax etc etc and hear about this knocklink all the time, can someone tell me what a knocklink is and what it does, and also how much it costs?

 

It's a sensor that detects pre-detenation, a common fault on scoobs that are not mapped for UK fuel. Pre-det is where the fuel\air mixture detonates before the piston has completed its up-stroke. You can imagine how bad that is for an engine. The knocklink will advise you when your car is doing thsi so you can do something about it, like back off the throttle

It's only a couple of hundred quid (probably less) and without one you run the risk of your engine going bang.

 

I'm sure some better people than me will answer this and also point out where I'm wrong :-)

A knocklink indicates detonation or pinking, this where the fuel air mixture in the chamber of each cylinder will ignite under pressure by itself (ie without the spark plug providing the spark). This is a bad thing for various reasons. A petrol engine is not designed for detontion (a diesel one is). The results of this can cause major problems all the way up to complete engine rebuilds (holed pistons etc). Turbo engines are prone to detonation because of their setup.

A knocklink effectively listens to the engine and gives you a nice green, yellow or red light as it hears louder and louder noises. Detonation produces a high pitched noise, hence being called pinking, as the noise within the engine rises then the yellow and red lamps on the knocklink light up.

This way you know when det is occuring. Almost. Most people using their knocklinks with the sensitivity turned way up so it catches any noise what so ever. Also occasionally you'll see a red lamp for an instance, which is not necessarily a major problem.

But at least this it's a good warning of if you have something majorly wrong and can prevent you from blowing the engine apart from a bad remap or bad batch of fuel.

You have to see what you car likes in the way of fuel, I personally found BP Ultimate to give me more lights than Optimax, whether that relates directly to det would require something like det cans (a set of headphones for a human to listen directly to the engine sounds) to resolve.

 

Wow nice replies guys, but how come turbo engines are worse for it?

 

I have a fully de-catted MY95 with normal Z4 ecu, and running standard boost.

Since buying in April always put Optimax in, and also last couple of months used Millers Octane Booster too.

Knocklink fitted couple of weeks ago, and on full throttle about to redline the knocklink stays in the green and doesn't get to orange.

Peace of mind monitor for me. I'd read that decatting can naturally up boost, so I wanted to check for myself all was well - as my engine has done 99k.

 

Would you say that running it on super unleaded is high risk or do other import owners use it?

There's no optimax around by me, SUL or BP Ultimate is the best I can get.

I dont want to inadvertantly blow my engine up!

 

scoobysport, turbo cars run a lot hotter temperatures than normal cars so this is probably why pinking kills them. pinking is not good for any engine. most turbo cars run richer to help combat this thats why scooby's have black exhausts. when you use uk fuel in a jap car that was mapped for Jap fuel it can cause pinking. the knockling allows you to monitor this. BR Developments sell them and they are fairly easy to fit.
ken

 

Knocklink is shown half way down the page HERE
Would prolly be wise to run on 97RON and Octane Booster

Cheers

 

You can buy a kocklink for about £150 dont be fooled into having it fitted by someone else they are a doddle to fit red and black live and nuetral ,brown/black sensor.The knock sensor can be fitted any where on the engine in a central locasion. I fitted mine on the interooler bracket located on the engine.

 

Thanks guys

Well I'd better got meself some booster to be on the safe side then as I do like to give it a good thrashing now and again!

Would prefer to have it remapped for uk fuel but imagine thats a bit costly?

 

Their is a knocklink group buy, in the group buy section on here, £124 delivered
cheers paul

 

Not if you can source a 'scoobyecu' which has revised fuel/ignition maps and a higher boost target They are a little scarce atm but do become available from time to time in the For Sale Section.

Cheers