Lee

"trust me even WE (ford) play games with this...."
easy Joe
going to nooner?

mcollinstn

Intake length longer = lower rpm torque peak.
Intake length shorter = higher rpm torque peak.

We used to run a Hilborn style injector on an alky motor V8 dirt sprint. We would use the injector horn length(s) to tune for a particular track. This follows thru to 2 strokes, dirtbikes, drag motors, or anything else you want to mention.

Like was mentioned earlier, tunnel rams are for high rpm and are long runners. The runner length is not optimal, but is such so that they are STRAIGHTER, and do not induce the suspended atomized fuel to slam out of the airflow as it makes a "turn" in a conventional intake. Straight keeps the fuel in the airflow. Long just happens to be the only way to keep them straight.

JSV

hey guys

Im running a Holley tunnel ram with fuel injection and it mid ranges as good as my blower did. The misunderstanding with tunnel rams is that drag racers use them with extremely wild cams that make power at unrealistic rpm for boats. The tunnel ram has long equal lenth runners, perfect for making torque.

JSV

Here is a picture

Cord

You know, there's another board member that's running a fuel injected tunnel ram on a Fountain too! Man, what a small world!

jdnca1

Good point JSV;

I'm running a Dart tunnel ram on a 632" Merlin, 2X775 Race Demons, motor makes big torque in the mid range and idles at 650rpm in gear. Cam is solid roller 280/288 @.050 115 centerline.

How do you like your holley injection...I almost went that route, but holley was not comfortable with it in my app 2 yrs ago and is was expensive.

audacity

the theory behind a long runner or tunnel ram is: as a very high velocity is achieved (somewhere close to the SOS) the mass will gain a greater momentum and with PROPER cam timing, you can actually build a small amount of pressure prior to the valve. obviously reversion (cam timing plays apart also) is tuned with runner length as well. someone talked of suspending more AF??...a better example of that would be a carb spacer, which would increase plenum volume and supply a different pulse wave.

JimV

jdnca 1


I am using a Haltech system. It works great and laptop programable.



Cord,


JSV is my home computer. I should have said something

Drew

Is it worth shortening the runners on a 502mag MPI without having the runners extrude honed as ASM does. I fiqure about 3/4" but need to do more checking and measuring. I have access to machine shop to shorten runners easily and the cost is right! ASM wants to much $ but if I can do the shortening myself and it would help well why not? We are just cleaning up a 502 and while it is apart now would be the time. We were not planning on changing the cam at this time. Has stock Hyd roller cam.

Thanks

turbo2256

Drew,

You might look up the tec article Hot Boat Mag did on the 502 a while back.