Rush 2.5s vs Rush/FuelMoto
Road Master
Joined: Oct 2007
Posts: 781
Likes: 1
From: Cave Creek, AZ
RE: Rush 2.5s vs Rush/FuelMoto
Interesting note about his kit. One pipe is restricted to a 3/4" hole and the other is a 2.0" hole. Combined area of these two holes is 3.58 sq. in.
Combined area of two standard 1.5" baffles is 3.53 sq. in. A reduction of 0.05 sq. in. Not enough to really change things IMHO.
Why post this? Because cross sectional area has a great deal to do with flow capacity. There may be some scavenging advantages to the pseudo 2:1 from fuelmoto that allows for better performance than dual 1.5's, but only testing would quantify that.
As for dual 2.5's, my guess is that the head pipes are the flow limiters and that scavenging is greatly reduced because the headpipes effectively dump into open air since the baffle diameter is so large. That might be good for a high rpm race motor, but can't be good at all for low/mid torque....
I've done a little playing with exhaust systems in the past. Just thought I'd throw some of that out there for you all to chew on.
Combined area of two standard 1.5" baffles is 3.53 sq. in. A reduction of 0.05 sq. in. Not enough to really change things IMHO.
Why post this? Because cross sectional area has a great deal to do with flow capacity. There may be some scavenging advantages to the pseudo 2:1 from fuelmoto that allows for better performance than dual 1.5's, but only testing would quantify that.
As for dual 2.5's, my guess is that the head pipes are the flow limiters and that scavenging is greatly reduced because the headpipes effectively dump into open air since the baffle diameter is so large. That might be good for a high rpm race motor, but can't be good at all for low/mid torque....
I've done a little playing with exhaust systems in the past. Just thought I'd throw some of that out there for you all to chew on.
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
RE: Rush 2.5s vs Rush/FuelMoto
ORIGINAL: CKinAZ
Interesting note about his kit. One pipe is restricted to a 3/4" hole and the other is a 2.0" hole. Combined area of these two holes is 3.58 sq. in.
Combined area of two standard 1.5" baffles is 3.53 sq. in. A reduction of 0.05 sq. in. Not enough to really change things IMHO.
Why post this? Because cross sectional area has a great deal to do with flow capacity. There may be some scavenging advantages to the pseudo 2:1 from fuelmoto that allows for better performance than dual 1.5's, but only testing would quantify that.
Interesting note about his kit. One pipe is restricted to a 3/4" hole and the other is a 2.0" hole. Combined area of these two holes is 3.58 sq. in.
Combined area of two standard 1.5" baffles is 3.53 sq. in. A reduction of 0.05 sq. in. Not enough to really change things IMHO.
Why post this? Because cross sectional area has a great deal to do with flow capacity. There may be some scavenging advantages to the pseudo 2:1 from fuelmoto that allows for better performance than dual 1.5's, but only testing would quantify that.
This combo provided the best HP and TQ, and it is definitely stronger and quieter than my previous 1.75" setup, both in low-end TQ and peak HP. I can see this on Jamie's chart and also feel it in the seat of my pants. I'm very happy with it and wouldn't change anything, except perhaps to add a mild cam, but that's not a short-term goal. As well as this engine runs I may just leave it alone.
Novice
Joined: Apr 2008
Posts: 17
Likes: 0
RE: Rush 2.5s vs Rush/FuelMoto
I just installed the fuel/motokit Monday.... So far so good.. Definate improvement in sound... I may have to lean it up a little for mileage according to some other posts that I've read here. Snowed the dayI installed it so hopefully I'll get to do the seatof the pants Dyno Friday
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Novice
Joined: Apr 2008
Posts: 17
Likes: 0
RE: Rush 2.5s vs Rush/FuelMoto
You may want to ask Jamie about the modified K&N air intake he came up with. Apparently some members have had trouble with oil belching back into the air cleaner on the standard K&N, his is supposed to cure this. I went with the Arlen Ness Big sucker
Extreme HDF Member
Joined: Sep 2005
Posts: 11,615
Likes: 50
From: Baton Rouge, LA
RE: Rush 2.5s vs Rush/FuelMoto
ORIGINAL: montanatinman
You may want to ask Jamie about the modified K&N air intake he came up with. Apparently some members have had trouble with oil belching back into the air cleaner on the standard K&N, his is supposed to cure this. I went with the Arlen Ness Big sucker
You may want to ask Jamie about the modified K&N air intake he came up with. Apparently some members have had trouble with oil belching back into the air cleaner on the standard K&N, his is supposed to cure this. I went with the Arlen Ness Big sucker
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