Thread: Custom Header Test's

2 quick questions please:

1) If you a change to your motor - like say a header - and the AFR's get richer in say the peak power rpm range after the change. And assuming no tuning was done after the change, then does that mean the modification was a step backwards? Or is it possible for the AFR's to get richer and the motor to make more power with the modification done.

2) When talking about header sizes, are the sizes referred to ID or OD? If a size is stamped on some tubing, does that generally refer to the ID of the pipe?

1.)I am not 100% sure what you are trying to describe, but in this case the engine ran much richer and still made more power

2.)OD when talking about headers.

1) I recently changed collector sizes on my header and noticed AFRs at WOT went from 13 to 12.2. Just trying to understand if that automatically means the motor is now breathing less (i.e. Less air + same amoutn of fuel as before = richer AFR), or if it is possible to get a gain in power wile still seeing richer AFR's after the collector change. Tuning is via standalone and TPS+RPM based so no chance of the tune richening up itself.


2) thanks.

1) In my case, the richer conditions were linear with power gain. I am under the impression that the header increased flow/efficiency. The increase in injector duty cycle after the header change also ensured what I already assumed.

I am also tuning via TPS.

increase in Volumetric Efficiency = numerically lower afr with more power.

Special Delivery from the other mad-man.

Got lift?

Oh. My. Lawd.

If these hit the sweet spot, someone is going to want what you've got now.

I hope these things do awesome. 300+ on the way hopefully. Cant wait.

All out race block build is coming. You can have this one whenever you are ready



Will start the work needed to fit these bad boys this week. Should start testing shortly after.

So i know modification to the valve guide to lower the seal and then grinding of the pivot point of the rocker arm so the lobe doesnt contact? Am i understanding that correctly?

Sounds like fun.