Mods and dyno's

[sleek98]

Is the dyno on 93 octane or race gas? Your tune should be adjusted for modifications such as headers and pullies. This doesn't sound right to me.

No tune update is needed as long as your not on the ragged edge timing wise. If your running an aggressive tune and running 91/93 i would suggest verifying with the tuner that the timing is good for the additional air.

The maf reads how much air is going into the motor and adjust the fuel for it. Doesn’t matter if it’s a 2.6 or a 2.4 pulley it will just move the fuel and spark to the next point on the map. Same thing with headers a little more air gets picked up and a little more fuel gets added.

The only thing for headers would be the transport delay could be adjusted.

This is why some people swap from say a 2.9 whipple to a 4.0 whipple without a tune change for dyno comparisons and it doesn’t blow up. I would suggest looking at the logs to verify.

 

[mebetter]

No tune update is needed as long as your not on the ragged edge timing wise. If your running an aggressive tune and running 91/93 i would suggest verifying with the tuner that the timing is good for the additional air.

The maf reads how much air is going into the motor and adjust the fuel for it. Doesn’t matter if it’s a 2.6 or a 2.4 pulley it will just move the fuel and spark to the next point on the map. Same thing with headers a little more air gets picked up and a little more fuel gets added.

The only thing for headers would be the transport delay could be adjusted.

This is why some people swap from say a 2.9 whipple to a 4.0 whipple without a tune change for dyno comparisons and it doesn’t blow up. I would suggest looking at the logs to verify.

Sounds very reactive. I would rather be proactive and have my tune right first rather than counting on the MAF and knock sensors to work as a bandaid. It only takes going extremely lean and hitting a lot of knock once at these power levels to see the motor go boom boom. $200 tune or $20,000 engine the choice is simple folks

 

[mebetter]

For the record I have similar modifications as the OP, but I’m tuned by AED. If I would have told AED I’m going to hammer my car after I did the 10% lower on the same tune as the 2.4 upper only he would have asked me if I lost my ever loving mind.

 

[50stangpower]

No tune update is needed as long as your not on the ragged edge timing wise. If your running an aggressive tune and running 91/93 i would suggest verifying with the tuner that the timing is good for the additional air.

The maf reads how much air is going into the motor and adjust the fuel for it. Doesn’t matter if it’s a 2.6 or a 2.4 pulley it will just move the fuel and spark to the next point on the map. Same thing with headers a little more air gets picked up and a little more fuel gets added.

The only thing for headers would be the transport delay could be adjusted.

This is why some people swap from say a 2.9 whipple to a 4.0 whipple without a tune change for dyno comparisons and it doesn’t blow up. I would suggest looking at the logs to verify.

I understand your point but I don't believe that is good advice. With long tube the 02 sensors are moved. This does change certain peramiters. I don't consider myself a pro and would like to heard an experts opinion.

 

[sleek98]

I understand your point but I don't believe that is good advice. With long tube the 02 sensors are moved. This does change certain peramiters. I don't consider myself a pro and would like to heard an experts opinion.

It does change the o2 transport delay like i mentioned in the first post. Some tuners change it but some don’t as the computer will learn either way on the transport delay. Lund changes it from the get go so they don't have to later on if you add long tubes. Which is why the OP was told his current tune is fine.

Sounds very reactive. I would rather be proactive and have my tune right first rather than counting on the MAF and knock sensors to work as a bandaid. It only takes going extremely lean and hitting a lot of knock once at these power levels to see the motor go boom boom. $200 tune or $20,000 engine the choice is simple folks

The whole point of the MAF is to read the amount of air that is incoming into the motor. It then calculates the amount of fuel needed. The WOT fueling table is targeted lambda, it uses the MAF data as well as the fuel injector data to compute the lambda, it then adjusts based on the widebands. Assuming the MAF and injector data are correct and to the tuners liking before the pulley swap, the computer simply moves to a higher up data point in the table. If you have the fuel system to keep up there is nothing to worry about on the fueling side.

The timing side you might need to change depending on how aggressive of a curve you are running. If your not sure then by all means shoot your tuner a message and ask them. I have ran 20* of timing on pump gas knowing that I was on the edge using 2.4, I now run 17* of timing and could some boost if needed but I don't want to push my luck on pump gas. On E85 I will add more boost (adding a 10% lower) and up the timing back into the 20* range.

I would tell you that you lost your mind as well running 91/93 on a 2.4/10% combo, that is just too much air for the octane. If you were on E85 or 116 it wouldn't be an issue. As proof look at the OPs car. It didn't blow up, and wont.

Edit, I even went back and looked at my logs pre long tubes and post long tube install that was on the same tune. At redline the lambda and STFT are basically identical. .776 lambda vs .780 STFT was .961% vs .922%. Throughout the curve it mirrored one other +/- .01 some times the stock manifolds were leaner some times the long tubes were leaner. Both logs bounced between .77 and .80 overall.

 

[biminiLX]

That's the beauty of dual wide band O2s with commanded a/f.
I'd definitely verify with datalogs, but Lund and other tuners do set up parameters that allow certain mods to be done without needing tune changes.
It really depends on how much airflow increase the mod makes.
Also, it's impressive how much detonation resistance E85 gives, I run 24-25 on E85
-J

 

[Bytor]

When I talked with Lund, I specifically brought up the transport delay but they already knew all that good stuff since I was asking them about adding headers. I'm running race gas, 102 octane. That was built in my original tune and on the last dyno, it ran 18*.