confused
#31
03-17-2018, 10:41 PM
Outstanding HDF Member
got the head pipe from a forum member who lived close by- thanks jbfb!😊
just now ordered the fuel pack 3 from mgs performance parts, on sale for $329. now all i need is more consistent weather and i will pull the bike out of storage and start work! wont be long now!
just now ordered the fuel pack 3 from mgs performance parts, on sale for $329. now all i need is more consistent weather and i will pull the bike out of storage and start work! wont be long now!
#32
03-17-2018, 10:48 PM
Stellar HDF Member
#33
03-18-2018, 02:13 AM
Road Captain
Sorry my friend...removing the cat and changing pipes are still well within the capabilities of a stock HD air cleaner.
I'm fully aware that most aftermarket A/C manufactures state their system allows (or will accommodate) for "X" amount of CFM's (airflow).
Try this...there are about 1700 cubic inches in a cubic foot. If the engine is a stock 103 and it's running at about 3000 rpm, the air flow is about 180 CFM's. The stock HD air cleaner is rated at something like 500 CFM's. The max airfow for a stock 103 at 7500 rpm is about 420 (according to some of HD's air flow figures).
Installing a system that will accommodate air flow over the capabilities of the stock engine will not cause the engine to suddenly increase it's max CFM air flow. It's going to take major modifications to the internals of the stock engine (like I said before, intake, pistons, and the such) before a "high flow" system begins to be effective.
Now if someone wants to add one of these systems to their bike, then I would certainly not stand in their way. It's just that many such aftermarket systems boast of significant increases in power and performance over stock but fail to mention (except the very small print) that engine modifications are really needed to see those same gains.
Hope that helps.
I'm fully aware that most aftermarket A/C manufactures state their system allows (or will accommodate) for "X" amount of CFM's (airflow).
Try this...there are about 1700 cubic inches in a cubic foot. If the engine is a stock 103 and it's running at about 3000 rpm, the air flow is about 180 CFM's. The stock HD air cleaner is rated at something like 500 CFM's. The max airfow for a stock 103 at 7500 rpm is about 420 (according to some of HD's air flow figures).
Installing a system that will accommodate air flow over the capabilities of the stock engine will not cause the engine to suddenly increase it's max CFM air flow. It's going to take major modifications to the internals of the stock engine (like I said before, intake, pistons, and the such) before a "high flow" system begins to be effective.
Now if someone wants to add one of these systems to their bike, then I would certainly not stand in their way. It's just that many such aftermarket systems boast of significant increases in power and performance over stock but fail to mention (except the very small print) that engine modifications are really needed to see those same gains.
Hope that helps.
One thing these calculations fail to take into account is the amount of vacuum necessary for given flow rating, and the fact that engines close to or at WOT generate very little vacuum, so multiplying displacement times RPM and comparing to CFM ratings is likely very misleading.
Most stock engines, whether on bikes, passenger vehicles, or whatever respond very well to modest improvements to intake flow, and you can see this in throttle response and fuel economy so long as ECM/carb is able to maintain proper air/fuel ratios (hence the tune/map req'd for some applications).
Last edited by ratpick; 03-18-2018 at 02:20 AM.
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