I am curious to learn how the experienced tuners tune cars on the dyno. I had my car on the dyno last week with my new set up. I am currently running a top mount with an SC61. My last setup was a ramhorn and a 60trim and I made 425@15psi. I always check the plugs after every pull. I pulled 2.5* of timing from my map before I made a pull and then I would increase it from there again if I needed. I made a pull, shut it off and checked the plug and it turned out that the timing was good and no sign of detonation at all. I look over to the dyno graph and I only made 412!!! I changed the plug for another new one gapped at .026 to make sure the timing shown on the plug was right. The plug show good again and still the same power. I added 1* of timing to see what change in power I would see. Well, power jumped to 426! but the spark plug shows that it is a little too advanced. Now, my question is, do you guys keep adding timing until you find peak hp/tq and then back off a bit and just make sure there are no signs of detonation on the plug? or do you just look at the plug and set timing accordingly? I am new to tuning but I am not afraid of it at all and that's why I do it to my own car. Peak timing for the 412whp is at 14.5*@15psi. My last setup was on 17*@15psi. Both on 91oct fuel. Thanks!

 

One at a time please! thanks!

 

Do you understand how to read color markings on the ground strap and porcelain? What's your target afr?

 

I have a good understanding on it. My afr's were mid 11's to low 11's. As it sits the mark on the ground strap is right at the bend. I believe I can have it just past the bend and that is where it was with the extra 1* I added. With cali pump gas I decided to leave back it back off but could I be adding more? I took the efi101 class a little over a month ago and my instructor said he never looks at the spark plugs anymore when on the right dyno, but I am still used to checking them. Do you do the same?

 

i would always check the plugs for safety sake. have you tried increasing the plug gap any at all.

 

For your instructor to say he never checks plugs is crazy. You want the color change to be more towards the apex on the ground strap.how's your Porcelain for a reference to ensure you're at the right a/f for the motor?
Honestly u may be a tad rich. Im proficient in tuning with evo's at 8.8:1 cr they're normally tune for a mid to high 11 as a target afr but those are boost levels in excess of 28 psi. I understand combustion chamber is different and that changes the propogation of the flame front. But theory is still the same in all motors. Do some moe research be you tinker with the motor. Knock is no light matter. It can destroy a motor in a few miles

 

The porcelain on the plug was clean, pretty much still white with some color down inside the plug. What I was told was that on the dyno you would increase timing until it stops making power. Now a 14hp increase from adding 1* I think is still a lot and I could see a good bit more power by giving it more timing. It seems odd that with the new turbo and manifold it would want that much less timing at the same boost level and netting me less hp. The plugs were also checked in the same manner on the last setup.

 

honestly you might want to lean the motor out to low 12's and see if you net any gains. ideally you want to advance timing until you encounter knock (maximum timing for best torque) than back off 2 degrees so you leave your motor with a margin of error, be it octane,temps or whatever other factor. but your motor likes what it likes. i would suggest tuning the ignition timing to your plugs rather than power output. only because you want a clean,crisp running motor.

 

Um....NO. 2 degrees before knock sets in is definately not always ideal timing or MBT. It depends on the motor, but it can often be very different than where knock begins. For street tuning, your method works ok, but on a dyno, you can find MBT before knock occurs.

 

agreed. there are many instances where mbt is 14-16 degrees before audible knock is reached - proven on a dyno. there are many cases where tuning til knock and backing off is way too much timing and is not a proper method of tuning.

 

I had it running high 11's afrs (11.7-11.9) but decided to run it a little richer and it only lost 2hp so I decided to keep it richer. Basically, I was told that you tune ingnition timing on the dyno so there is no real need to pull plugs otherwise I could do it at the track or on the street (safe area), but I just want to see if others are tuning the timing according to what the power output shows on the dyno and then just checking plugs for signs of detonation.

In the efi101 class the instructor demonstrated this on the dyno. The window between MBT and knock was huge! but it was not at WOT or under boost which I'm sure makes that window a lot smaller.

 

i would try another degree while monitoring knock and check your plugs again. monitor power change. if it stops picking up or is only picking up a little, this is where i'd stop and this is where your judgement comes in to play and you ask yourself those questions to figure out if the extra 20-30 hp is more important or where the color mark is on the plug is. you can figure out what timing's making the best power, back it off to where the color mark is, and if you ever need those 20-30 extra hp, adjust it again... just continue monitoring the plugs and knock.

 

If you only added 1 degree, and your power jumped THAT much, and it wasnt a glitch or spike in the graph, you are no where near MBT, and you are reading phantom spots on the plugs.

Also, how much did you let the car COOL between pulls? You want repeatable results...

 

Thanks Xenocron.

It was not a glitch for sure. When we first started we where tuning off the wastegate at 11psi and made 365. Checked the plugs and looked too advanced so we backed of timing. I saw power drop fast along with my jaw LOL. I ended up pulling 2 degrees there to get the plugs right. Power ended up being 338 or so at that boost level. I doubt I am reading the plugs wrong but maybe I am. A new plug went in every pull. We let the car cool off to about the same ect and iat. This is why I figure I was far from MBT. Like I said, I am new to this but I also want to make good power and still be safe. I know of many that go off the dyno graph when tuning timing so give me some advice. Thanks!

 

good info

i would agree with xeno, If you gain that much power, you are far from MBT

 

Ok, so how can you tell if you are close to MBT without reading the plugs? In other words, when at a dyno, how can you find MBT? It has been said that the best way to find MBT is at a dyno, but hasn't been said how to. Or is it that the best way to find MBT is by looking at the effects on power by changing timing?

 

Sorry to bring this back but I am planning to go back to the dyno soon. I would like to know what TUNERS are using to monitor knock or how they decide when to stop adding timing. I dont know if I mentioned it before but I was on 91oct pump gas and I am pretty sure I will not see MBT on it. I will be doing a pump gas and race gas tune.

 

im still a noob only tune my own car, but I will start by adding 2 deg at a time until I make less than 10hp then I add 1 deg at a time until I only make 1 or 2 hp, after that I pull 2 deg just to be safe. I would also like to hear how some of the more experienced tuners do it

 

When I took the EFI 101 course a couple years ago, I was taught to basically tune each load point and rpm seperately until you have a general timing curve you can fine tune. Of course starting with a good basemap will save lot of time also...
While on the dyno, say at 3500 rpms and at 15" of vacuum (part throttle) ,hold the engine rpm with the load bearing dyno and increase timing to that exact point until you see no more increase in TQ. Once you have found this point of maximum TQ for that particular rpm and load, this is your MBT at that exact point. Repeat for the rest of the rpm range and throttle positions. Correct me if im wrong, but this is how i remember it..

 

What spark plug are you running? Do you know how to read spark plugs well enough that you know you're running the correct heat range?

Running an incorrect heat range will lead to incorrect spark plug readings.

 

I am just getting into tuning as well, and i was wouldering how do you know when you are at max timing?... and is there a good web site where you can go to to learn how to read spark plugs? How do you no if you are using the right spark plug heat rang wise . . . Sorry hope im not buging just wanna learn and learn right...
Would really appriciate it Thanks...

 

How do you know if you have the right heat range spark plug?

 

http://www.dragstuff.com/techarticle...ead-plugs.html

 

Thanks Really good reading really appriciate it...