knock Sensor

You are going to have to change out the entire ignition to do this. Something like Electromotive.

What is in there now isn't set up to read and manage a ping.

You are just better off using premium gas and not worrying about it unless you want a an expensive project.

 

Ferrari puts the V8 knock sensors to the side of the valley where it curves upward just below the intake ports of the heads. 2 on each side. I guess a good welder could weld small mounting lugs up there to bolt them to.

 

You know, I mentioned just using premium fuel instead of fabricating an anti-knock system... The irony of it is if you do get something like that up and working - you will HAVE to start using premium fuel or risk losing performance.

 

That's not the way my Motec EFI works. I agree with using better fuel, but if you don't, It just retards the timing a few degrees if it detects knock.

 

Guess what happens when your timing is retarded

 

It doesn't knock.

 

It is only temporary and guards the motor from bad gas which has become very common.

 

I know.

And knock sensors are proven technology but I often wonder the point of this exercise of retro-fitting one to anything. Really all you need to do assuming you are in good tune, is use premium, right? If he is looking to save money at the pump, I just don't get the economics of the conversion. How many decades is it going to take to recoup the investment considering how many miles these cars are driven.

But if he is doing it to bump up the advance for a little more umph, the last thing you would want is a fuel that is more likely to keep retarding the ignition - so your back to pumping premium again.

I'm not trying get to suggest any of it is a bad idea, just when you start thinking about your goal for a moment with all this...

 

Frankly I would like to see where this goes. If I convert to a different ignition like I asked you about in another thread, I would think you would need the sensors.

 

I wanted too....

 

Well few modern high performance cars could function without them. Gas is very bad and even more inconsistent yet we have cars with 11:1 compression and supercharged cars with considerable boost. Supreme gas is just not good enough to allow that without detonation protection.

A 308 or 328, TR, any of that era of car had pretty low compression, super is really not needed. But put a blower on it, supreme gas or not it's going to need detonation protection if you have any intention of trying to taking advantage of what the mods can do for you. Not to do so is just leaving performance on the table.

 

Pick a sensor but I'd locate them in the same place Ferrari did.

 

Have you ever drilled a 308 block for sensors?

I don't have a problem being your first customer if you haven't. When mine finally tires out I want to rebuild with a slightly higher compression and better ignition. Nothing extreme, just a nice stockish upgrade that could go another 100,000 plus miles. I would be happy with 328 performance.

I don't think it would make any sense not installing a knock sensor if I eventually get to that point one day.

 

I wouldn't drill it, I'd have a good guy weld an aluminum lug on the block and bolt it to that.

My 328 is bored and stroked to 3.5L and has almost 11:1 pistons in it and does not have any detonation problems. With CIS injection which I kept, it does not breath well enough to get a big enough charge in the cylinder for detonation to be an issue. I have the stock ignition too with it set to the European advance curve. The Italians have always used longer slower curves than we tend to here. If an aftermarket system was installed it may get to be an issue even with the CIS but have not made that particular modification.

 

As stated, knock sensors are for your protection. I run very high boost levels ~25 PSI (over 500 rwhp) and it protects your engine from detonation. Even if you carefully program your fuel and timing curves, you may find areas where you can still experience detonation. Bob Norwood once told me 'by the time your hear detonation, it may be too late' (at high boost levels). Even for non turbo or super charged cars, detonation is a killer.
One note- Knock sensors must be carefully calibrated or they will detect knock where non exists (false positive). If you have a quality EFI system you can tailor the amount of timing and/or add fuel to suppress the knock.
In the end, you can tune closer to the edge with a properly setup EFI/ knock sensor. But it is no substitute for quality fuel. That's why I don't use pump gas. You have an expensive car. Don't use a cheap EFI system if you choose to go that route.