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Knock Retard



I didn't know there was a max for KR. So do the pistons chip because the engine cannot retard it enough to prevent damage?
 
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:th_nervous::th_nervous::th_nervous::th_nervous::th_nervous::th_nervous::th_nervous::th_nervous::th_nervous:
 
03GTPLE said:
I didn't know there was a max for KR. So do the pistons chip because the engine cannot retard it enough to prevent damage?
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Yes, but it doesn't need to be at max retard for this. Damage can happen at any level of knock, the likelihood of damage just increases with increased retard (because increasing retard indicates continued knock). Remember, the sensor must see knock before the PCM can pull timing to retard knock. Any knock-inducing detonation could cause damage.
 
There is never going to be a scan posted up because I'm pretty sure he won't know how to upload it or he borrowed the scanner blah blah blah. He will probably come back on here and tell us he has 4* of knock max when he really is hitting 8-14*.

Maybe we should re-title the "safely modding your 3800" with "HANNAH MONTANA NAKED - HAVE A LOOK INSIDE;)" I gaurantee everyone in this site will have colonel knowledge of the 3800 after that.
 


matt5112 said:
Supercharger - Wikipedia, the free encyclopedia

Proof that you CAN'T run a smaller blower just because you're higher up and you have thinner air....

Your blower is even LESS efficient at altitude.
Click to expand...

A supercharger, and a turbo, and any thermodynamic cycle involving air (otto, rankine, whatever) is less efficient in higher altitude.

I've never once said anything about efficiency.

But, since you brought it up...

My argument is that you can run a BIGGER supercharger at altitude (seeing as there is less air to compress - or you could call it reduced efficiency).

In WW2, they HAD to run airplane superchargers at altitude, with more boost the higher they went precisely to overcome the thin air.
 
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As tempted as I am to respond in kind to calls of be being retarded, Jewish (though I take no offense at that), too stupid to figure out how to post a video, too stupid to tell the difference between 4 and 14, owner of a engine that should have blown up, owner of an engine that should have 14* KR, I won't.

Instead, I will post something constructive for someone who might come to these forums to ascertain knowledge.

Here are three video with real-time knock retard monitoring, all at 100% throttle, from a dead-stop to ~70MPH. This is at my altitude, 5500ft, with a 3.2" pulley, and 85 octane gas.

I ran three pulls from a stop (on these videos) and the max KR I saw was 4*.

Here are the vids:

Video #1

Video #2

Video #3

This was tough to record seeing as I was driving alone and trying not to kill myself (probably the stupidest thing in this thread - and that's saying something).

Please note: the TPS registers 100% for the whole pull - every pull.

Here are some pictures of my car to show the pulley and scanner:

3.2" pulley installed

Snap-on scanner

Engine bay (no mods - cast iron headers and standard intake)

I don't have the data cable for this scanner or I would post full 20 min long snapshot movies documenting that KR NEVER goes above 4 degrees (and I see 4 degrees for a grand total of about 2 seconds in 20 min of driving with ~10 0-75 pulls).

In spite of being treated like an idiot, I'm still happy that I came here. At least it gave me a reason to see my uncle (whose scanner I used).

If the 4* is problematic, I can always switch to 91 octane gas. But, from everything I've read (not here mind you) about KR, 4* is not that bad.
 
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Given the fact that I can switch to 91 octane and I don't drive the car with 100% TPS for ~8 consecutive seconds in real life (just for the purposes of those videos), I think I can turn 4* into 0* pretty easily.
 
SJAndrew said:
Given the fact that I can switch to 91 octane and I don't drive the car with 100% TPS for ~8 consecutive seconds in real life (just for the purposes of those videos), I think I can turn 4* into 0* pretty easily.
Click to expand...


Dude, at a minimum, please call Clint. He can tune the PCM. I'm sure there's a lot going on in the tune that you aren't seeing other than the 4* of knock.

If you insist on not doing any other mods to the car, I don't know if you could even do a mail order tune (which is normally suggested) because it'd be waay of.

There's a lot of resources for you in Denver, use em man.
 
4* on a 3.2 is a bad thing.

But the point i was trying to make is that because you're at a higher alititude, your blower is putting out even hotter air than it would at sea level. That means more mods for a certain pulley size.
 


It also means the hotter that thing gets...and the smaller the pulley gets the more prone you are to pre-detonation...which means that 4* on a 3.8" is MAGNIFIED on a 3.2" probably 3 or 4 times. I just can't believe someone with a boosted car won't run a high octane...I mean...are you really hurting to where you won't spend the extra $3 at a the pump every fill up?
 
Colder REALLY don't do much. You just want a colder spark when you drop pulley sizes...he would probably be one of the people to try and kill the knock with a 160* and Autolite 103's.
 
Just so you guys know, there is another guy in Colorado that has simliar claims....... but Zoomer fed the ideas to him. (run a smaller pulley due to altitude; yeah, I understand your stance against ZZP ;) ) He had it on his car for years and he bought the car new. He's since sold the car, but he claims to never have problems.
 
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