Dyno tuning

[HNK]

Hi

What is the best way to dyno tune to extract power at different RPMs? What i had in mind is try a set figures for timing and fueling and see at what figure is max power and torque gotten, then change accordingly? Do you tune ignition first for power then fuel or fuel first?

thnx

[truckguy]

Tune the fueling side first then the timing side. I go conservative on timing until the fueling is set and then creep in extra timing. Final timing should be the lowest timing number that made the most power.

[colamotas]

is that it

[Texsrt4]

i have found that when tuning lower throttle position fueling, its better to drive along and datalog as opposed to dialing it in on the dyno. you dont have realisitic airflow over the motor while on the dyno. even if you have a fan you dont get realistic airflow that changes over speed. i drive the car around first doing lower end fueling. then strap it down and do the higher end stuff

[Billf6531]

I vote for Tex

[Ben Diss]

i have found that when tuning lower throttle position fueling, its better to drive along and datalog as opposed to dialing it in on the dyno. you dont have realisitic airflow over the motor while on the dyno. even if you have a fan you dont get realistic airflow that changes over speed. i drive the car around first doing lower end fueling. then strap it down and do the higher end stuff

OK, but how do you know when the combination of air, fuel and spark is giving you max power at a given RPM? Curious.

[Gh0st]

OK, but how do you know when the combination of air, fuel and spark is giving you max power at a given RPM? Curious.

You can do several runs at different air fuels to determine which air fuel gives the best power.

Then you cando several runs with different timing. Whichever timing gives best power, stick with it. The goal is to find your MBT and go a tad below that so you have some safety.

Honestly the gains from max power to a slightly safer power range are very minimal. I'd rather take the safe power than the leaner power that only gives me 5 more hp.

[WS6FirebirdTA00]

Nor are loads (in most cases) accurate on the dyno

[Gh0st]

Nor are loads (in most cases) accurate on the dyno

My logic when tuning my car is to tune it on the dyno for scientific power purposes. Next, I put it on the street/dragstrip and do some runs to see how the car acts in the real world. Sure, you won't get power numbers, but you will be able to see how your air fuel works on the street and also more chance for knock on the street which will help dial in timing safer.

[WS6FirebirdTA00]

Exactly. The dyno is good to see what conditions the motor likes to run in. The load will change that a little bit, but you get an idea based on if the dyno has higher or lower load. After that, make some street or strip pulls and match the fueling back up to what you would like

[Texsrt4]

OK, but how do you know when the combination of air, fuel and spark is giving you max power at a given RPM? Curious.

air/fuel combination is factory controlled at stoich, so i narrow the fuel trims. the WOT stuff is done on the dyno to determine max power. while at partial throttle and mid rpm, there is no way to "maximize" power with certainty. sometimes you can loose power by adding timing. dynos dont accurately let you do partial throttle pulls like that. while cruising set your timing to a couple degrees below knock threshold and you should be close

[Texsrt4]

this is always funny. i have customers ask all the time about how i go about tuning. they look at me like im some retarded monkey when i say that i prefer to do most of my tuning on the street. having a $50,000+ dyno in the back, with all the sensors and i prefer it on the street, i must be crazy. but the truth of the matter is that a dyno only gives numbers to compare with your buddy or an easy way to go WOT and make sure your afrs are ok.

in the real world, however, we drive at varying loads and varying rpms. you cant really do this on the dyno, so thats why i spend as much time datalogging and tuning while on the street. only WOT tuning gets done on the dyno itself

[Redline MS]

Nor are loads (in most cases) accurate on the dyno

Why? Dynamic Cylinder of 1.02 is the same load regardless of a dyno load or a road load. Its 1.02 load.

Granted you can't always hit certain parts of the load table that you can hit on the street, like hard decel, but its all relative. I'll do as much as I can to AutoVE tune most of the VE table and then street cleanup the rest.

[WS6FirebirdTA00]

Yes, if that is what you actually got on the dyno. Like I said, MOST cases, the dyno load will be different. I go from the street on a good tune, say 13:1 AFR. Go on a 248 dyno, AFR drops to 12.3:1. I lean it out to get it back where I have it on the street, power goes up, g/cyl go down due to the change in fuel calculation because of the load change on the motor. We tune vs MAP in the VE, not g/cyl. MAF cars are not AS sensitive to it (fueling wise) but it has happened.

Again, this is not something every dyno does. I have been on 3 different dynos and all of them were different on my car.

[Texsrt4]

Yes, if that is what you actually got on the dyno. Like I said, MOST cases, the dyno load will be different. I go from the street on a good tune, say 13:1 AFR. Go on a 248 dyno, AFR drops to 12.3:1. I lean it out to get it back where I have it on the street, power goes up, g/cyl go down due to the change in fuel calculation because of the load change on the motor. We tune vs MAP in the VE, not g/cyl. MAF cars are not AS sensitive to it (fueling wise) but it has happened.

Again, this is not something every dyno does. I have been on 3 different dynos and all of them were different on my car.

bingo. on a roller style dyno you cant hit real load cells because you cant load the car like you can on the street. you cant hit the cells you need to hit (lower rpm higher load), so you miss PRIME knock cells on the dyno. similarly, if you have a hub mounted dyno you put more load then normal meaning you miss the cells on the high side, missing the not quite wide open throttle areas.

[Ben Diss]

My AFR is exactly the same on the dyno or the street. I don't understand how it would change?

[WS6FirebirdTA00]

Again, it changes from load. Sounds like your car has a similar load on the street as it does on the dyno.

[Redline MS]

My statement was based upon the use of a Eddy Current load control dyno. I use a DD unit which is really stable.

VE is based upon load (grams/cylinder) vs. rpm or by MAP. Either way once you have reached that cell you are there. I will dial in 70% of my tune on a load dyno and the other 30% on the street. This usually yields a well rounded tune. Comes in handy when tuning a 800+RWHP E38 car!


Howard

[Texsrt4]

My AFR is exactly the same on the dyno or the street. I don't understand how it would change?

if you have a modification that varies depending on airflow it makes a difference. an intake on a corvette for example, changes airflow on the dyno or on the road. if there is no air moving across the filter it works well, but i had to adjust the maf when we drove the car after we were done tuning it. his trims were +/- 1-2% on teh dyno, when we were done and drove the car his trims were +8-10%. that tells me that airflow matters

[Ben Diss]

if you have a modification that varies depending on airflow it makes a difference. an intake on a corvette for example, changes airflow on the dyno or on the road. if there is no air moving across the filter it works well, but i had to adjust the maf when we drove the car after we were done tuning it. his trims were +/- 1-2% on teh dyno, when we were done and drove the car his trims were +8-10%. that tells me that airflow matters

I hear ya, I just can't wrap my head around that. Seems to me then, the tune would only be good for one gear. 0-58 in 1st would be rich while hitting redline in 3rd at the end of the 1/4 mile, you'd be lean.

I don't see it on my scans. Dunno why I'd be any different. What am I missing?