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70Barracuda

St Lt Knock Question

I had good luck with my R/T by advancing my timing and adding fuel, I consistently showed decent results at the drag strip.   I never did much data logging as I found it kind of a pain with the Predator, but I didn't get real aggressive with things so I felt fairly safe that I wasn't causing any problems.  At the time I generally added a can of Torco or added some race fuel at the track and all seemed to work well. 

 

Now I have a 2014 SRT and a Diablo Trinity I figured I'd try to do something similar at the track but also figured I'd data log at the same time.  I put in the 93 tune added a full can (32 oz ) of Torco and proceeded to make some runs at the drag strip.  I made some runs with the 93 canned tune and some by advancing the timing 2 degrees and adding 2% fuel.  Well I was surprised when I saw how much ST knock I was getting and that on at least one pass I got 1 degree of LT knock.

 

Not really knowing all the in's and out's of this tuning stuff I don't know 1) how concerned I should really be and 2) what the best way would be to get rid of the ST and LT knock (if you guys think it needs to be eliminated). 

 

On the 93 canned tune run I ended up getting 4.5 degrees of ST at around 4,015 rpms (30 mph), another 4.5 ST at 4,777 rpms (92mph) and again at 5,967 rpms (116 mph).

 

Here's a screen shot of the 4.5 ST at 4,777 rpms:

 

runE92_zps117c1fb5.jpg

 

Here's one at 5,967 rpms:

 

runE116_zps6cfd9d04.jpg

 

Here is a screen shot of the log I ran on the 93 tune + 2 degrees advance +2% fuel that I got the 1 degree of LT knock on:

 

runDadvanceLT_zpsadc3baed.jpg

 

I guess I'm looking for the best way to reduce the knock and get the most out of the tune.  I hate to add a bunch more fuel and wet down the plugs in order to eliminate the knock and I also hate to retard the timing as that just goes against what I want to achieve.  I've also thought about just adding race fuel at the track, but although there isn't much lead in it I still hate to add leaded gas to a catted vehicle.  I'm open to hearing any thoughts or recommendations you guys may have.

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Back off the timing.

 

Afr on the runs?

 

AFR gauge, something else I probably need to invest in.  As far as backing off on the timing I was thinking of trying the 91 canned tune next time out and then if things looked alright maybe bumping timing a bit from there.

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1-2 st knk is not much too worry but drop the timing at least to that and to eliminate ALL the LT knk. Without an Afr gauge you shouldn't jack with the fuel much at all. Just my opinion but I think others will agree for the most part.

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17.5 degrees with 4.5 ST knock?  Wow, back it off and get a tune, nothing good comes out of those canned tunes.

 

x10

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Like others have mentioned don't mess with the tune until you get a wideband installed so you can monitor WOT fueling. Get the fuel close then experiment with the timing. If your car is stock I would start with the 91 octane tune, we had the best results performance wise with that tune on the dyno with stock vehicles.

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If you're getting that much STKR adding timing is pointless as it's just being pulled anyway.  That's a LOT of timing being pulled.  Make sure the little caps on the knock sensors aren't loose.  Log Knock Sensor Volts 1 and 2 as well and see what they're doing.  Get a wideband as mentioned above.

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17.5 degrees with 4.5 ST knock?  Wow, back it off and get a tune, nothing good comes out of those canned tunes.

 

 

x10

 

Thanks for the advice guys.  B)

 

Like others have mentioned don't mess with the tune until you get a wideband installed so you can monitor WOT fueling. Get the fuel close then experiment with the timing. If your car is stock I would start with the 91 octane tune, we had the best results performance wise with that tune on the dyno with stock vehicles.

 

I'll go back to the 91 tune and work from there.  Do you think I'd see an benefit by going with an email tune ?, the car is totally stock although I plan to do at least a few mild mods in the near future. 

 

If you're getting that much STKR adding timing is pointless as it's just being pulled anyway.  That's a LOT of timing being pulled.  Make sure the little caps on the knock sensors aren't loose.  Log Knock Sensor Volts 1 and 2 as well and see what they're doing.  Get a wideband as mentioned above.

 

Thanks for the input Speedy, I'll add those two to my log.  I'll have to get a wideband but didn't figure I needed one for a stock car that I was only going to make minor adjustments on, I guess I'll have to rethink that.

 

Quite frankly I was very surprised to see that much STKR coming off of a canned 93 tune, I'm also considering the possibility that my local gas stations 93 rated gas may not be anywhere near what it claims, but then again I figured the can of Torco would help make up for that.

 

I'm thinking I'll put a different brand of gas in on the next fill up then log the 91 and 93 tune to see if there is any difference.

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When my car was stock I did a lot of logging looking at afr and timing for a couple years to try to squeeze a little extra out. Found out it really wasnt worth the effort but it did pass the time and was part of the hobby. I got an email tune from Johan and that seemed to help a little with the butt dyno but didn't make much track difference. I say its not worth it to mess with it beyond just going with the can tunes and leaving them alone or getting one email tune and be happy with it. There really isn't a whole lot a room to play regarding performance improvement without some major mods. Which is why when I figured that out I dumped the stock engine and started from scratch on a forged block with more cubes for future performance gains. I think there was a thread a while back on small mods and if they made a difference or waste of money and the consensus was waste regarding performance. Looked at as things to do as a hobby, that's another story. To get noticeable gains, you will either have to supercharge, bigger cube block, ported heads, etc., not cheap mods of course but they produce results.

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When my car was stock I did a lot of logging looking at afr and timing for a couple years to try to squeeze a little extra out. Found out it really wasnt worth the effort but it did pass the time and was part of the hobby. I got an email tune from Johan and that seemed to help a little with the butt dyno but didn't make much track difference. I say its not worth it to mess with it beyond just going with the can tunes and leaving them alone or getting one email tune and be happy with it. There really isn't a whole lot a room to play regarding performance improvement without some major mods. Which is why when I figured that out I dumped the stock engine and started from scratch on a forged block with more cubes for future performance gains. I think there was a thread a while back on small mods and if they made a difference or waste of money and the consensus was waste regarding performance. Looked at as things to do as a hobby, that's another story. To get noticeable gains, you will either have to supercharge, bigger cube block, ported heads, etc., not cheap mods of course but they produce results.

 

I agree with what you are saying for the most part, but in my case I'm not looking for the big gains (at least yet).  With only a bit over 2,000 miles on the car I'm not ready to sink the money into forging the motor and super charging it.  Presently my goal is to just try and crack into the 11's, which I think is a very doable goal as others have already done this with minor mods. 

 

With my R/T I was able to go from a 13.68 to a 12.87 (an 8 tenth gain in similar DA) with just minor things like drag radials, bigger TB, CAI, high stall converter, cat back and making adjustments to the canned Diablo Tune.  I'm hoping to be able to find similar results with my 392.  Currently I'm sitting at a 12.39 so I guess I'm looking for the next step to eke out a bit more.

 

The R/T seemed to respond real well to bumping the timing a few degrees on the 93 tune (also added fuel) when running race gas and I was looking for that with the 392 as well.  However, it is starting to look like the 392 Hemi is going to be a bit of a different animal when it comes to this.

 

Plus quite frankly I enjoy the whole process of changing a few things here and there and looking for that extra tenth or two.  So like you say it's part of the hobby and until I'm ready to dump in some bigger bucks it gives me something to play with in the mean time.

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Plus quite frankly I enjoy the whole process of changing a few things here and there and looking for that extra tenth or two.  So like you say it's part of the hobby and until I'm ready to dump in some bigger bucks it gives me something to play with in the mean time.

 

I like doing that as well, knowing what gets me what at the track.

 

I'd skip the Torco and get some real race gas.  Run the car down to almost empty on the way to the track, or drain the tank at the track, and throw in 5 gallons of MS109.

 

What's your STKR look like without the adjustments you're making?  Could be something mechanical knocking on something.

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Plus quite frankly I enjoy the whole process of changing a few things here and there and looking for that extra tenth or two.  So like you say it's part of the hobby and until I'm ready to dump in some bigger bucks it gives me something to play with in the mean time.

 

thumb.gif

 

Get a wide band o2 and an AFR reader. Know where you are fuel wise is key at any mod level. Helps you make small fuel adjustments in different temps, ie, go little fatter in cool air and little leaner in hot to keep you in the 12.3-12.6 range for an n/a motor. Without the afr, you are just guessing and that's not a good idea.

 

Here is a good thread on afr:

http://modernmoparforum.com/topic/11766-what-is-the-best-afr-for-na-power/

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I like doing that as well, knowing what gets me what at the track.

 

I'd skip the Torco and get some real race gas.  Run the car down to almost empty on the way to the track, or drain the tank at the track, and throw in 5 gallons of MS109.

 

What's your STKR look like without the adjustments you're making?  Could be something mechanical knocking on something.

 

I can get Sunoco 112 at the track but of course it's leaded, I've run that in my R/T and it seemed to work great but I hate to put too much through it.  I haven't tried it in the SRT yet, but I may try to get ahold of some MS109, there is a VP dealer not too far from me but he only stocks the leaded variety but will special order.  I also have a line on some 100 octane aviation fuel, which is low lead, not sure how compatable it is.  I know the specific gravity (or something like that) differs from auto fuel, but I also know a couple guys that run it in their classic muscle cars.

 

When I refuel again (I'll try a different brand) I'll go out and do a couple data logs, maybe run a stock tune and a 91 canned tune and see what I come up with.

thumb.gif

 

Get a wide band o2 and an AFR reader. Know where you are fuel wise is key at any mod level. Helps you make small fuel adjustments in different temps, ie, go little fatter in cool air and little leaner in hot to keep you in the 12.3-12.6 range for an n/a motor. Without the afr, you are just guessing and that's not a good idea.

 

Here is a good thread on afr:

http://modernmoparforum.com/topic/11766-what-is-the-best-afr-for-na-power/

 

Thanks for link and advice, good info.  B)

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What's your STKR look like without the adjustments you're making?  Could be something mechanical knocking on something.

 

Made a quick data log last evening, did a WOT run with the 91 canned tune and saw 2 degrees of STKR, then punched it from a roll and had a spike of 3.5 STKR.  The 2 degrees of STKR doesn't seem too far out of line with what others tend to get, so I guess I'll have to work from the 91 tune for the moment.  I'm going to have to experiment with different fuel brands and also make a few runs with true race fuel.

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Throw race fuel in there and retest.  On race fuel you shouldn't get any STKR, if you are I would suspect something is rattling or tapping on the sensors causing it.

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Where are your coolant and oil temps?

 

A meth kit, properly mixed and setup, could eliminate all of that. An oil cooler might help too.

 

I didn't monitor those during the prior test runs but will probably have a closer look at them the next time I head to the track.  Currently I'm still running a stock t-stat but I have a 180 that I will be putting in.  I've thought a bit about a meth kit and I may go that way eventually but at the moment I'm just trying to see what I can squeeze out of the car relatively stock.

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Fwiw, your timing and knock numbers are very similar to what I tested in my stock 6.1 back when it was stock. I did about a dozen WOT pulls with the stock tune and each of the DS canned tunes, logging each run, and then look at the averages. I also ran the numbers through TTdyno to see where power levels were.

 

I'm a data nerd like so many others here lol lol

 

The 93 CAI perf tune outperformed all others by far on my car; giving me an average increase of 23hp and 23tq... however average stkr increased by a full point also. With this tune I saw anywhere from 1.5 to 4.0 degrees of stkr; unfortunately I didn't log ltkr. My base timing was in the low 20's before knock, and then into the high teens after knock, just like yours is doing.

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