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Discussion Starter #1 (Edited)
I haven’t seen a topic about this so here is my opinion. Someone will probably bash this post but what the hell. I’ve seen more than one dyno posted by manufacturers that make no sense. Which leads to the beat down topic that aftermarket exhausts, intakes, and headers don’t do jack for the VVTI motor. Why? You have absolutely no control over fuel mapping. You can’t add more air and not more fuel without running lean. Which is why intakes are gutless on the bottom end. Not enough fuel. Not to mention an 18 to 1 air fuel ratio before 3000 is absolutely ruining your motor doing daily driver stuff. Same thing with uncorking the exhaust. Can’t add more air because you can’t add more fuel. Unichip? Still not enough control and when it fails you have a 5000 lb brick. Moving on to dyno sheets. A dyno sheet for something that you had no fuel mapping control over was a total waste of time besides bragging rights. Ultimately all you did was pay for a piece of paper with numbers on it. It didn’t help you tune your truck in other words. Which is what you go to a dyno for. Motorcycle guys that have full control over their bikes know what I’m talking about. Fudging the numbers. A topic that I haven’t seen covered is wheel spin on the dyno. Which will throw readings off as the wheels lose traction. First you will see a dip in the readings followed by a spike when the wheels gain traction. To illustrate this effect I’ve attached a dyno sheet from an unnamed manufacturer. They claim this was completely stock truck vs stock truck with headers. As you can see by the way the power curve paints out. This isn’t the truth. IMO this is a dyno comparison of the same part. Not a stock truck vs new part truck. Why? It’s usually marketing bs that’s at fault when you see this. At least this company provided an actual dyno sheet instead of a trend graph like I’ve seen elsewhere. Mostly likely the bottom end suffered because of fuel mapping changes you have no control over. Why 17 dyno runs. Most likely they couldn’t beat the stock part on low end even though they tried many times. So they didn’t even compare it. You can use this method to effectively sniff out bs dynos. Especially if they provided the whole graph. Including A/F read outs.
 
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