Boat engines run very similar rpm to buggy and truck engines. Some reaching 40,000rpm+. Marine inboard engines are often timed somewhere between off-road and onroad surface engines - and even the 7.5-11cc engines reaching in excess of 30,000rpm. Ducted fan airplane engines aren’t much different.

Start out with the link that Roelof posted, it will give you a rough idea. I also posted names of some other people who have written some books.

Worth mentioning is that they use formulas derived from testing, so for what ever engine you might run it might not work perfect even if you use any of their formulas. Everything is fine tuned after to get the desired results, but funny enough, if you have a pipe that works well it can often work on engines that's not exactly the same.
That's one reason why they for instance use the same divergent and convergent cones for pipes with different EFRA number (sometimes), they just fine tune the rest of the pipe to change it a bit.
There is nothing that say that you can't use another brands pipe on your engine, not sure where you got that from.

[QUOTE=SlowLST2;15177166]Why would Anyone use proper spelling, punctuation, and grammar? I mean, you do want people to take what you say seriously, right? I don’t, but some still may..

When it comes to pipes - there isn’t much magic behind it. As I said before - the differences are going to be either/or/or a combination of different volumes, shapes, and sizes/lengths of the tuned section. Nothing mystical here - one pipe to the next is just a little bit different. In all honesty - where I have seen the most change is within the manifold. You get a much more dramatic change with the engine when you change manifolds than you ever will changing pipes. Neal has a dynongraph here somewhere I’ll try to find.[

u and everyone else that is offended by my writing please feel free to skip over my post and feel free not to read it, its a free world and I choose to write this way thanksss

[QUOTE=ralphierace13;15177794]Ralph why you getting guys butthurt on here ? LOL :lol: and in all my years of racing I never seen anyone use a off-road pipe on a on-road motor and vice versa.

[QUOTE=BigC2007;15177838]Some people were using off road pipes back when they were trying to get the virtus to make time...

way back when before all the craze with on road torque motors I had murnin modify me an off road motor I forgot which one but was the top one at the time.
I was so excited to try it I said that's it I going to blow everyone out of the water with this the low end will be insane and bla bla bla, so I broke it in nice.
and showed up that sunday for the race ready to destroy everyone with my new secret weapon I bragged about all week to the guy!!! so went out for practice with everyone and just got blown away lol!!

went back to the pit took it out walked over to the trash can and just dumped it!!!! lol last time I ever tried that....

u can run onroad motors off road but never the other way around really don't matter how much toque if u don't have them rpm's it over....

[QUOTE=BigC2007;15177838]The 9901 is still a populair offroad pipe but has started as a new 3 chamber onroad pipe and so the 2015 and 2052 are well used in both classes.

[QUOTE=BigC2007;15177838]There are pipes that are both thin walled and thick, to be used as either onroad or offroad, for instance pipes from Novarossi and Hipex.

It's a bit incomplete, hard to say what went wrong, what engine he used to tailor it for onroad etc.
For instance, some offroad engine have smaller crank case and smaller ports, if this isn't dealt with you can end up with a bad combination.
But on the other hand, it's probably cheaper to modd the onroad engine for a little bit more bottom end, if that's what you need.
The engine in itself doesn't know if it's a onroad engine or offroad, that's a designation we give them and as such it's up to us to make it work, by both knowledge and trial.

[QUOTE=Roelof;15178088]I believe the now not legal pipe 9886 was onroad from the beginning as well, and that's just from Novarossi.
Others that spring to mind is: 2069(2120), 2013, 2116, 2032. But there are a lot more, though I believe not all are legal for onroad, and in offroad you might want a thick walled pipe. Other then that, mix it up and test it! :)

Another oddball pipe is the corked up 2015 pipe, 3007, though it didn't work in onroad I had success on some of my offroad engines.

no nothing went wrong it just didn't have the power of an onroad, off road has less rpm's and even thought was modified just didn't have the top end, but motor worked ..

Well it impossible to both have the cake and eat it, if you modd an offroad engine to have the same power at the same rpm as the onroad engine you're back to square one. :)

I see what u are saying, the reason I did it was I guess I was before my time and way before they started making on road engines with all this torque.

so I thought back then I would have such an advantage with a high torque motor that I would of blown them away so bad out of the turns I would have been gone plus the mod work to help keep me ahead on the straight away!!!

but it just didn't work that way the onroad was just overall more powerfull !!!

so anyone tested the new 41613 manifold?

Question fellas, I have .21 Flash on a MRX6. What fuel would you recommend? I'm in Miami, FL which means its almost always hot. Thanks for the help!