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| Tocchi |
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i've been told that the older intake is better yet i see so many people doing the BBM conversion. so im a little confused.
what are the pro's and con's of each system? |
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| stockstandard |
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The log manifold isnt bad, apparently very slightly stronger at high rpm (debatable), but the BBM = Lots more torque and a fatter power band.
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| smiley235 |
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bbm adjust a different length for air flow suited for above a 2800rpm which length would be not suited for low rpm. I've never heard of the old intake system being better before.
basically, bbm = (effectively the old system under 3000) + (a better system over 3000)
_________________ 178.3 rwkw
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| Tocchi |
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cool thanks for that info guys.
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| stockstandard |
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smiley235 wrote: bbm adjust a different length for air flow suited for above a 2800rpm which length would be not suited for low rpm. I've never heard of the old intake system being better before.
basically, bbm = (effectively the old system under 3000) + (a better system over 3000) Not entirely accurate The switch point is at 3800rpm (not 2800) The log manifold is about the same as the short runners on the BBM, so it is comparable to the BBM above 3800rpm. The long (low rpm) runners on the BBM are much longer and give the engine more low down grunt. And while the runner length of the log is the same as the BBM at high rpm, the BBM has the butterfly valves between the plenum and the short runners. You only have to look at it to see that this is going to be some sort of restriction to the airflow. The only person I know who did back to back dyno runs before and after a BBM conversion lost 2rwkw but gained a lot down low.
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| smiley235 |
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sorry, I know its 3800 but when I typed it, I went blank and typed 2800 for some dumb reason.
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| Andrew J |
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The log style manifold is meant to be better for forced induction, specifically the ed ones though isnt it?
_________________ The problem with America is stupidity. I'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself?
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| moody |
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jump on www.jimmockmotorsport.com and read there articles, it clearly states the bbm is the best for power and that the ef intake tubing is also better then the el's.
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| Tocchi |
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yeah i remember the EF vs EL debate a while back.
what about the AU tubing? |
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| Pulco |
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isnt it the same as el?
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| stockstandard |
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moody wrote: jump on www.jimmockmotorsport.com and read there articles, it clearly states the bbm is the best for power and that the ef intake tubing is also better then the el's.
Be very careful about taking what you read as fact, especially when it is written by somebody who makes money in the field. JMM will tell you that the EF tube is better, G&D will tell you the EL/AU pipe is better.
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| cjh |
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The BBM on EF, EL, AU's was fitted for several reasons. For starters, they, FORD, have to meet emission regulations, this leads to less power, so delvelopment of an induction system, with out being forced, is needed to get power back, so having a switchable dual length air intake runners, makes for a longer, broader power band, a flatter, longer torque curve. When you have a fixed runner length, EA-ED, you are stuck with having a set tuning, a narrow power, torque curve. But this is for naturally aspirated engines, this all changes with forced induction.
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| stockstandard |
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cjh wrote: The BBM on EF, EL, AU's was fitted for several reasons. For starters, they, FORD, have to meet emission regulations, this leads to less power, so delvelopment of an induction system, with out being forced, is needed to get power back, so having a switchable dual length air intake runners, makes for a longer, broader power band, a flatter, longer torque curve. When you have a fixed runner length, EA-ED, you are stuck with having a set tuning, a narrow power, torque curve. But this is for naturally aspirated engines, this all changes with forced induction.
The BBM had nothing to do with meeting emissions as the log manifold continued to be used until the AU came out (without any changes to the power rating). Also the EB/ED XR6's have higher rated output with the log manifold than the standard EF/EL falcons with BBM's, and I dont recall any new emissions standards coming out in that time. It is just an incremental refinement on the 4.0's. As you say, fatter power bands, more torque, all up a much better street manifold.
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| cjh |
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Okay then, so why did the EF have a coil pack & the EL go back to a distributor, then the AU's went back to coil pack & sequential injection?
Because Ford jumped the gun on the up coming emissions regulations,(on the EF) which was costing them approx $100 per car to build. Notice too that Ford went to Visteon components for the ingition on the AU's. They also went to a new coolant with the AU's, an EPA friendly one, which turned out to be crap, it ate conventional gasket material, absolutely hammered the mechanical seals on w/pumps, leached through hoses, but it was EPA friendly, not component friendly. Automotive manufactures have to follow rules, so they'll make their product as cheap as they can whilst sticking to the rules, thats how they make money. Ever noticed that the service schedule never really suits average joe? They make it that way for the fleet buyers, and to satisfy others. Notice Ford doesn't have a diff oil change in the schedule, for The falcons & their derivitives? Why is this? Any component that runs in oil, has varying temps, has bearings & gears, etc.. makes metal particules, those then contaminate the oil, so it needs to be changed. eh?
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| stockstandard |
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Jebus talk about going off on a tangent...
You are right, ford do lots of things for lots of different reasons. What all the stuff you posted has to do with what is being discussed in this thread is beyond me. All im saying is that if ford wanted to reduce emissions (which they didn't have to do), then their are easier way to do it. If however they wanted to improve the power delivery of the engine (i.e. make a better car for more sales), then a dual runner intake is an excellent way to do it.
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