How Much Knock Is Safe?

**SlowRR** · 11-17-2010

I have a 2000 GTP. Its got very few mods, 3" catless downpipe, zzp pcm, CAI, Msd coils and wires, ac delete, and a set of Flowmasters. I have but not instaled a 160 t stat and 104 plugs. I am slowly trying to get to a 3.4 pulley so I bought the parts just not put on yet. Well I just put in my aeroforce gauge and took it for a ride and I'm getting KR readings as high as 3.6. Still running a stock pulley I'm kinda shocked by this so it has me wondering at what level should I be concerned when I step up to the 3.4?

**machinegunsquid** · 11-17-2010

Well if you're getting that on a 3.8" pulley, you're going to need quite a few more mods. Best bet would be to get a set of headers, go back to stock coils, and get the S/C ported.

My car had 0 knock when I dropped to my 3.4", and now that it's getting cold, i see 1-1.5degrees of knock under full throttle now, with the mods in my sig.

I also wouldn't go with a 160* thermo, read the write-ups about engine longevity vs. colder thermostats.

And if I read that right, it sounds like you're going to put the 3.4" with the engine already knocking, if so, that'd be a bad idea.....

**rynoman03** · 11-17-2010

Ported Supercharger and throttle body helped me alot with my KR. I got it done by Reptile. Also sell your dp and get headers. You're engine will thank you.

**GAFF** · 11-17-2010

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**SlowRR** · 11-17-2010

I just don't understand where it is coming from, mentioning stock coils, are they better then MSD or is it that there less power? Also from what I understand most off the shelf tunes are set up for 3.4, claiming it helps reduce KR. The dp even though its not headers still helps to reduce KR too. Do they have KR in stock trim, I just don't see what I did to add KR seeing how everything I added so far is to reduce. I'm not planing on running a 3.4 till I get this figured out. If it is the PCM and I go back to a stock tune with the DP will the SES light just come on or will it be running in some sort of limp mode. I live in Chicago and have to take emmisions which was the main reason for pcm purchase

**kfish** · 11-17-2010

yes gtp's knock completely stock. some dont, but most do. i think there was someone on here seeing upwards of 6* bone stock.

**SlowRR** · 11-17-2010

Well that makes me feel a little better. Maybe I am making progress, still a long way from a pulley though.

**MrPoopyButthole** · 11-17-2010

I knocked 10* at bone stock.

I knock about 2* with headers, 1.9s, 3.4, 3.5" Velocity stack intake, 10.3 zzp wires, copper plugs.

I plan to get a custom tune in the spring and be at 0*

**matt5112** · 11-17-2010

I saw at MOST 9* of KR bone stock while being naturally aspirated...

with headers it was 2-4*

And this was on 94 octane...

Right now I see blips of up to 1.5* with a top swap with headers and a 3.8 pulley.

160 thermo is good if you're hot lapping, not if you're DD'ing it.

It all depends where you are.

Stock, under 5 is okay.

3.4: under 2

3.2 under 1

Further? No idea... probably not much...

**MrPoopyButthole** · 11-17-2010

But if you can custom tune and work it to 0* you will have a happy motor

**matt5112** · 11-17-2010

its always better to have a safe zone between where you knock and where you are.

**01gpgt01** · 11-17-2010

If you're not knocking any your tunes not aggressive enough. I generally keep it under one. every so often I get a small spike of like 1.12 or so. MSD coils are said to be based off GT coils FWIW

**MrPoopyButthole** · 11-17-2010

Rubbing cheetah bloodz on the motor you will get 0 KR and 30whp

**machinegunsquid** · 11-18-2010

Originally Posted by DrunkietheBear

Rubbing cheetah bloodz on the motor you will get 0 KR and 30whp

Lol, damn I gotta get me some cheetah blood then. XD

Anyways MSD coils have been known to go bad. I have them, and the first set, all 3 coils literally split open within 3 months of having them on. MSD said "sorry, have theses and some money" And they've been fine since.

But I saw no performance increase, its all just for show really. If mine go out again, Im gonna get my money back and just get stock coils.

Also, a DP will help reduce KR, but not NEARLY as much as headers. Also, the off the shelf PCM tunes seem to be hit or miss, so try to find someone who can tune for you.

**blueguy** · 11-18-2010

Set some shiz straight here.

MSD Coils are eye candy, like stated. Keep the stockers. A 160* T-Stat is for someone who doesn't really DD their car or who lives in a HOT ass climate IMO. Keep a 180* all the time and be happy. Knock wise, you always want 0*. No knock is good knock, nor is acceptable. The LARGER the pulley size, the more forgiving knock is, but the smaller the pulley, the more devastating knock can be at lower amounts.

Example: 6* on a 3.4" might be 14* MAX KR on a 3.8"...or, 2* on a 2.6 is like 10+* on a 3.4" or so...make sense? 3.6* isn't BAD, but it isn't great either. Rule of thumb is each degree of knock pulls about a degree of timing...and each degree of timing pulled is about 5-7 whp on average. MY BET...is the fact you NEED to install a 180* T-Stat...should help a little...also...flip your front dog bone mounts, as it could be false knock from the DP hitting the sway bar by chance, unless you flipped that...then that rules that out. Another thing to ad...is your tune. ZZP PCM's are known to have issues...I bet a custom tune would get rid of all of that knock anyways.

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