Loafington
Active Member
Is there an intake manifold out there for 117" S&S engines that have a longer intake runner for a single G?
Intake Manifold
- Thread starter Loafington
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Loafington
Active Member
Must be a tough question....
Guess it is!! I can't answer that for you but would ask what it is you want to do. Seems if you have a longer runner it will stick out interferring with your leg unless you get one of those elbow things.
Interested to here what you are going to do.
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Interested to here what you are going to do.
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Loafington
Active Member
It does interfere a little. I was looking for information as to whether or not increasing the intake length would be of any value.
Last edited:
Loafington
Active Member
Thanks man. I was thinking the same thing. I was just wondering it a manifold existed that was already longer. Adding spacers does the same thing.
Loafington
Active Member
Has anyone installed any one of these? If so, was there any noteable performance increase? What modifications were needed if any? I am looking for anyone who installed these, not just on a Big Dog, anything...
http://yostperformance.com/products/images/s-s-spacers-L.jpg
http://yostperformance.com/products/images/s-s-spacers-L.jpg
rainyknight
Member
Loaf, I've always run a 1" spacer on my S&S carbs. the Super E and G carbs were designed as "shorty" carbs because of clearance issues. The old Super B and D carbs had longer bodies. There is a noticeable change by installing the spacer. You may need to rejet as it changes the intake tract length.
"Intake runner length can be used to tune an engine based on pressure waves or sound. The shorter the runner length, the higher the engine rpm in which the tuning effect will take place. Runner length is measured from the carb entrance to the valve seat. The length of the intake manifold, carb spacer, carb body and velocity stack or radius ring will vary runner length and change the point of peak horsepower and peak torque. Knowledgeable engine builders use intake tract components as "tuning" tools to shift the engine's power band either lower or higher, help diminish reversion pulses, stabilize the air/fuel mixture, and improve the combustion process."
I remember seeing a longer curved intake a custom bike down in Daytona but I don't know if it was a production item or not.
I hope this helps you out.
"Intake runner length can be used to tune an engine based on pressure waves or sound. The shorter the runner length, the higher the engine rpm in which the tuning effect will take place. Runner length is measured from the carb entrance to the valve seat. The length of the intake manifold, carb spacer, carb body and velocity stack or radius ring will vary runner length and change the point of peak horsepower and peak torque. Knowledgeable engine builders use intake tract components as "tuning" tools to shift the engine's power band either lower or higher, help diminish reversion pulses, stabilize the air/fuel mixture, and improve the combustion process."
I remember seeing a longer curved intake a custom bike down in Daytona but I don't know if it was a production item or not.
I hope this helps you out.
Loafington
Active Member
Is there a rule of thumb...shorter spacer for power in lower rpm ranges, longer for higher?
I would compare it to a car application. Dual plane vs. Single Plane intakes. Dual planes are shorter and cater towards a street car and a broader torque curve and lower hp peak. The single plane is going to be for a more radical set up and drag or track use. Adding the spacer will increase your peak horsepower number and probably at a higher rpm. I see maybe 10 hp on 600-700 hp motors with a 1 inch spacer. I'd change to the S&S long filter first. I did notice a difference above 4500. My dyno showed my engine was struggling for air up top with my mixture getting fat.
Glad to hear that extension kit I sold you is still working strong and well!!
Loafington
Active Member
Not entirely true. Not all dual plane intakes are low rise, and not all single plane intakes are high rise. The biggest difference between the two, is runner, plenum design and length, not overall height.
I have never seen a single plane that is shorter than a dual plane or vice versus. The single planes are definitely a straight shot vs. the round about way with the dual planes. You just like to disagree with me. I have no problem with that. 
On the dog they don't have much choice on runner length. It's got to fit into a pretty small package. The Mikuni provides a little longer runner length. Still thing a bigger air cleaner is a smarter move than the spacer but you know everything so why did you ask? And GAS thanks for the extended filter it's working great.
On the dog they don't have much choice on runner length. It's got to fit into a pretty small package. The Mikuni provides a little longer runner length. Still thing a bigger air cleaner is a smarter move than the spacer but you know everything so why did you ask? And GAS thanks for the extended filter it's working great.
Loafington
Active Member
Ok, just because you never saw a single plane that was shorter than a dual plane does not mean that they do not exist, they are there, they are available, and that is that. You are correct when you say that there is a straight shot vs. the round about way. As far as "liking" to disagree. I do not like to disagree with anyone for the most part, I actually like to agree, and that leaves more time to do other things. Now, here is where it gets interesting; I do not know everything, but when someone gives information, information of which I do know something about, and I find that information to be inaccurate, I will call that person out, I don't care who it is, so don't take it personal.
Now, tell me how a bigger air cleaner will accomplish the same thing as a manifold spacer does. Explain how a Mikuni provides longer runner length than an S&S shorty style…and I do not know everything, which is why I did ask.
Now, tell me how a bigger air cleaner will accomplish the same thing as a manifold spacer does. Explain how a Mikuni provides longer runner length than an S&S shorty style…and I do not know everything, which is why I did ask.
There have been some members that have researched the CFM needed at high rpm vs. the air filter cfm rating. At high rpm the stock size is questionable. Adding the S&S extended filter takes it out of the equation. It made a noticable difference onmine. I don't think it will do the same as the longer intake but then you don't have room for the longer air cleaner. I wouldn't want the air cleaner out any farther.
The mikuni setup puts the carb close to parallel to the front head giving it more runner length. Couple here have run them.
Loafington
Active Member
You know what I am saying, it's just terminology, not literal sense.
Loafington
Active Member
Where can I look at the info regarding the filter numbers and Mikuni specifications? Have they been posted here before?
37% more flow. S&S Catalog Carb and fuel systems/page 26 No hands on experience with the Mikuni. Have seen them on many bikes. Sul and Al Hall both had them and now don't. They are your best bet for advice.
Loafington
Active Member
What is the CFM needed for the 117"?