intercooling 1981 8V turbo non-APC car

[matt]

detonation takes a long time to negatively affect an engine, especially in the situation we are talking about. you could drive on that engine for a month with detonation under boost before you saw any damage.

tell that to the kids running boosted hondas without proper (or any) tuning. One boost spike and they're buying new pistons and blocks.

Tolerating/allowing knock/ping/detonation in your engine is dumb.

[SaabsBreakDown]

detonation takes a long time to negatively affect an engine, especially in the situation we are talking about. you could drive on that engine for a month with detonation under boost before you saw any damage.

tell that to the kids running boosted hondas without proper (or any) tuning. One boost spike and they're buying new pistons and blocks.

Tolerating/allowing knock/ping/detonation in your engine is dumb.

sounds like a good reason to have a visual knock detector

sorry for coming off like an ass guys, i just feel strongly about this. if you hook up your light to the apc, or however you do it, it's nice to know whats going on especially if you think you may be close to the limits.

this is the one i had on my 16v turbo CIS 900 ems: http://www.viatrack.ca/

before I got that I was running around with 15 psi, after I got it I turned it down to 12 or so to get the knocking to go away. I'm glad I got it!

[Crazyswede]

You are more then welcome to run the knock sensor light. I personally would find it to be a distraction for anything other then diagnostic work. What would be better would be to set up a data logger so you could go for a drive and then look at the knock sensor history to see what you are dealing with. This would be especially useful if you also collected engine temp, throttle position, Air density, etc etc. The light is kind of like the blood trail for a wounded deer. It lets you know there is a problem but by the time you see the light/blood the damage may very well be done.

[Jordan]

I know pinging is unheard, but "visual knock detector" seems like an oxymoron to me

I had a vac line come off my wastegate in my 900 once and I sure heard the knock as the boost pressure approached 25psi... Obviously something was wrong and I didn't need a light to tell my that something was going on. If you are going so close to the ragged edge where you need a light , even small changes in outside temperature, barometric pressure, fuel grade are going to get you into trouble...and for what? Most people aren't building drag cars that operate for 10 second intervals and every 100th of a second counts so why push it?

As for you're "strong feelings" you are already changing your story from "knock doesn't really damage your engine" to "buy a knock light". It's fine to post when you "think" you know the right answer, but are wrong. But, don't assume you know more than any body else here and try to prove your point from extracting a few sentences from an internet site. We are going to call you out and you are going to end up just looking silly. Learn and educate yourself from others responses who probably know more than you.

[SaabsBreakDown]

As for you're "strong feelings" you are already changing your story from "knock doesn't really damage your engine" to "buy a knock light". It's fine to post when you "think" you know the right answer, but are wrong. But, don't assume you know more than any body else here and try to prove your point from extracting a few sentences from an internet site. We are going to call you out and you are going to end up just looking silly. Learn and educate yourself from others responses who probably know more than you.

I mentioned knock detectors should not be discouraged in my first post in this thread.

I eagerly await future teachings, Jordan!

[Jordan]

Sorry, it's hard to tell what is coming from you and what is regurgitated internet vomit.

[matt]

detonation takes a long time to negatively affect an engine, especially in the situation we are talking about. you could drive on that engine for a month with detonation under boost before you saw any damage.

tell that to the kids running boosted hondas without proper (or any) tuning. One boost spike and they're buying new pistons and blocks.

Tolerating/allowing knock/ping/detonation in your engine is dumb.

sounds like a good reason to have a visual knock detector

your missing the the point which is by the time they see the visual knock sensor they've already completely destroyed the engine. The better idea would be to tune the engine, make sure it's in good working order, and using proper fuel. I'll take avoiding knock over detecting it anyday.

[SaabsBreakDown]

detonation takes a long time to negatively affect an engine, especially in the situation we are talking about. you could drive on that engine for a month with detonation under boost before you saw any damage.

tell that to the kids running boosted hondas without proper (or any) tuning. One boost spike and they're buying new pistons and blocks.

Tolerating/allowing knock/ping/detonation in your engine is dumb.

sounds like a good reason to have a visual knock detector

your missing the the point which is by the time they see the visual knock sensor they've already completely destroyed the engine. The better idea would be to tune the engine, make sure it's in good working order, and using proper fuel. I'll take avoiding knock over detecting it anyday.

I dont disagree with your statements about properly tuning an engine.

My problem is that the following statement is false: "your missing the the point which is by the time they see the visual knock sensor they've already completely destroyed the engine."

It is misleading and this is a website where people can come and read these threads and never post, and for someone to walk off thinking that knowledge is truth is ridiculous.

Even top fuel cars can detonate for several revolutions before blowing up and sometimes drivers can hear detonation and kill the engine before it even fails.

Those cars are probably 1,000 times more sensitive to knock than a saab engine is, many of us have probably driven home from the grocery store on a hot day with an MBC and had knock. Our engines didn't fry the rings immediately and leave us walking home with our groceries. If there was a sensor with a light it would have illuminated before it even got bad enough to hear.

Knock is bad and should be avoided. However it is not instant death for an engine. This is very, very misleading, and also discourages people from learning more about the subject when phrased like that.

I'm sorry to see that knock detection is such a taboo on this site.

[Crazyswede]

No knock detector for you!!

[matt]

Knock lights are not taboo. I just see better ways to utilize time and resources to improve and protect your engine.

I would consider a knock sensor to be informative but certainly not a safety net. I would rather have an ecu that adjust boost, spark, fuel maps etc instantly than try to rely on me completing the long path to "lift your foot" which starts with "did I see something light up?"

My statement about turbo'd hondas blowing their motors the first time they go WOT and get knock is still accurate. I said nothing about Saabs blowing their motors that way.

However it is not instant death for an engine. This is very, very misleading, and also discourages people from learning more about the subject when phrased like that.

I don't see how that's misleading. Detonation can kill your engine the first time, or it can last a season at the track. It doesn't matter how long it takes, eventually you'll be rebuilding it instead of having fun. I think people will want to learn more about detonation and try to avoid it.

[SaabsBreakDown]

Cool. We agree then.

not sure why we got on honda engines, though..

[Luke]

the general opinion in the rally world seems to be that rocks banging off the skid plate are very loud and happen to be in a similar frequency range as knock. The result is a false signal and if your ECU is tuned to listen for it your performance will suffer for no reason. I have knock sensing on the electromotive but have it disabled.

[max]

If visual knock detectors were the way to go, then lots of people would have them. I can't remember the last time I even heard of someone running any type of visual knock detection (NOT including dataloggers) on any type of car. Knock can also be seen on a dyno output, so usually smart people tune knock out of their engines so it's not a factor.

[Hans]

...visual knock detectors...

I think you hear about it in c900/pre-Trionic 9k circles because you can easily set up an LED on your dash by grounding pin 19 on the APC (86+, not sure what the # is on earlier boxes). I don't know, though, if the light flashes whenever the sensor generates knock-induced current or if it flashes only when the APC has processed a knock signal, determined it to be real knock, and decided to bleed boost.

There's also a Volvo guy who sells a visual detector: http://www.viatrack.ca/

Detonation can kill your engine the first time, or it can last a season at the track. It doesn't matter how long it takes, eventually you'll be rebuilding it instead of having fun. I think people will want to learn more about detonation and try to avoid it.

+1

[saab_o_naut]

EZK and most modern ignition systems operate in the same way, effectively.

EZK sort-of knock-limited. It will periodically (upon each start-up??) advance the timing until it detects knock, then set a maximum advance that's a couple degrees less advanced. EZK does not allow the engine to continually run at the knock limit.

Knocking is not damaging to an engine unless it goes uncontrolled, and the whole point of his visual knock sensor is so he can detect and adjust the engine to stop detonating (knocking).

I agree that, lacking some sort of boost controller, a visual cue that the engine's unhappy would be helpful. But to assume that a turbocharged engine will tolerate a bunch of knock for long periods of time is tempting fate and, depending on the engine, not necessarily true.

Well this is why I'd like to do two things in the future - add a knock indicator (KnockSense being the preference), and maybe install an APC unit but only for knock control and nothing else. The car isn't designed to use APC and shouldn't even need it as I never run anything other than 98 RON premium ULP fuel, though part of the functionality could be helpful.

As a result of lots of discussions with other people I'm almost decided to avoid the T16 intercooler route with this car and opt for some sort of FMIC, esp. given that the air filter box arrangement would need to be completely changed. The air intake 'venturi tube' to the filter box mounts at the front facing the left side of the radiator so that's right in the way of where the T16 intercooler would sit, and unless the US cars, all our Australian c900's never had 'snorkels' of any sort for cold-air intake - the Australian specs required venturi-type intake tubes which just point up towards the underside of the hood/bonnet. Not exactly great for cold-air receival IMHO.

I will fit a T16 intercooler to my 16V n/a c900 soon but turbo-adding to that car is a seperate project since it already has all the electronics I need (EZK and LH), while intercooling the 81 8V turbo car is primarly a mechanical mod involving no electronics at all.

I do think it's worth checking timing, etc. though and once I sort out an oil leak (and a broken oil filter housing - check threads at my site, saabcentral, etc. abotu that!), the I/C planning will kick into high gear.

Craig.