You can find leaks etc. with just a simple run in stand. I can't tell you how many times I've seen with the chassis dyno guys who had big engine numbers of a crank dyno but the car was running numbers 75-80 HP off. Put it on the chassis dyno and it's where it should be.

Start asking the customer how the engine dyno was done and then you find out they had dyno headers. The ones that are really down on power used a dyno ignition and a dyno carb. Then it becomes a pissing match on how worthless a dyno is in general, when in fact it's not the dyno's fault, it's the [censored] testing methods.


I've seen bad headers kill a hundred HP like nothing. The difference between good headers is maybe 10 if you are lucky.

Most dyno headers have nice, long port exits with generous radii for turns whereas most chassis headers have very short (if any) straight pipe off the head and bends and kinks that are big flow killers.

I've always said if you are using production made headers the tubes need to be bigger than if you can build custom headers (like Elston and others do) because you can make the tubes with bigger radii (and fewer corners if you are a skilled craftsman like Calvin) and do things a production header can't.

Ive seen an MSD box be down over another brand by as much as 12 average and 15 HP peak from a Mallory box and I've seen that on several tests I've done. And the MSD box had been worked over by someone else. It made that engine builder have great numbers but his engines were never as good in the cars as they were on his dyno. He loved his dyno ignition, carb and headers.

I will say if you are having issues and you can use a known, tested carb or headers or ignition to find an issue that's one thing. To use that stuff to fluff your numbers is entirely another.