So i have been testing some onroad and GT car engines as of late, made some interesting findings about header length and just how critical it is to engine performance and that a onroad engine using a offroad manifold may not be as powerful as a offroad engine on a offroad manifold... For the onroad engine to really come alive it needs a proper onroad manifold... this is critical for GT racing where you must run a offroad manifold.

As you can see the Picco EMX is a monster on a proper onroad setup, but once I swap to the 41032 offroad manifold power drops off quite badly..... then on a offroad manifold vs one of my stout Offroad engines the EMX only holds a slight advantage in the top end, everywhere else its heavily outpowered....The default manifold for the onroad test is the Picco manifold that came in my 2116 combo kit.... I tried all the Nova manifolds but they all lost power next to the Picco manifold...the 9886 pipe made the most power out of all the pipes I tested.

And here is the EMX in both onraod trim and offroad trim vs my Paloma LTD on offroad trim

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Very interesting and thanks for sharing. Are you testing the EMX-GT or the EMX-WC in the charts above?

Probably it is the resonance timing that does not match the exhaust timing, an offroad manifold is much longer than an onroad manifold because the needed lower rpm powerband range.

I am also interested to see what an offroad engine does on an onroad exhaust system.

this is the WC...I also tested the EMX-GT a few months back......

Exhaust timing..the higher the exhaust timing the shorter the manifold needs to be.....this is why onroad based GT engines aren't going to pull like offroad based GT engines..

Great information, love the graphs!

both engines are modified !!!

Do you have the data posted on the EMX-GT? Any plans to get the new OS GT engine and give it test?

Friday Night and out in the shop playing with the dyno...currently modifying a Mito 35 WC..I have the engine up roughly 15% power over stock which is quite considerable considering how well done the Mito is from factory... Anyways here is my Mito 35GT vs a Picco Top Gun factory built Drag engine





I love my job sometimes...these onroad engines are a hoot to play with !

Do you have a standard Mito 35WC (onroad) not for GT, dyno results?

that is what this is..this is a modified Mito35-WC

I tried all the onrtoad tuned pipes, 9886 makes the most power and torque..so I posted the results from the 9886

I will do the Mito GT soon.....but from what i am seeing the onroad engines don't perform so well on offroad manifolds...they are beasts on the onroad manifolds, but they lose most of it when coupled to a offroad manifold..........

So what are they doing different with the GT class engines? I know they use a different liner and crankshaft but what's different with the liner? I'm going to be changing my GT engine to either the new Mito 35GT or the OS 21XZ-GT when it comes out. In the past I've always run the extra short or double-bend headers because I've gotten better top end with them. Should I be looking in another direction?

I need to re-test the EMX GT....I did dyno test one and it just didn't open up like I expected it to and since it was a customers engine I wasn't willing to push it further in fear of damaging the piston , my guess is the engine was just too tight to really open up and I did not have time to break it in further and do a retest !