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intake question


Guest Anonymous

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Guest Anonymous

Hi, I have the option of using an E46 or E88 intake on my n42 head and block. It is in a 71 240. I was wondering what the difference is in the two intakes and which won is better in terms of performance. Thanks.

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Guest zline

I havent heard of an E46 intake, there is an E31 and an E88 and as far as i knwo theyr'e the only ones prefixed with E, anyways

E88 is great, its essentially a E31 with 2cc larger combustion chambers

E31 is a GREAT n/a head if you're class restricts porting

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Guest Anonymous

It seems like you might be talking about heads not intake manifolds. I have an intake manifold that says e46 on it. Nobody seems to know what that is though.

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All of the E-series intakes are the same. I have an E-46 as well. I believe it was a shorter run of the casting as they seem to not be as numerous..

The N-series intakes from the 260's are said to allow for a slight performance increase, but I have never seen any flow numbers to substantiate that claim. If you have your intake apart, you might as well do yourself a favor and smooth out the inside of them. That will give you a little better performance by reducing turbulence and drag w/in the intake.

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Guest Anonymous

Thanks for your reply. Could you tell me the best way to smooth it out? Should I use sandpaper or a file or something else?

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Smooth what out exactly, the intake runner? If your working on an intake runner dont polish it, remove casting flash if you spot it but an intake is not to be polished internally on a street car. Low end response actually likes a little bit of a rough pathway.

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Guest Anonymous

Now I'm confused, one person has said to smooth out the intake for less drag, while someone else not to because it will be better in the low end. Can someone give me a definite answer?

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Hmmmm...

How would "rough pathway" aid in an intake charge. I would think ideally that the smooth intake runner would be beneficial in all cases, but significantly better at higher rpm's where the turbulence in the rough casting would be much greater. If a rough casting would be better for low end torque, then noone would ever polish the intake ports on a cylinder head on a "street" car. I believe the reason people don't polish the intake runners is that normally it would be too difficult to get the complete intake (Efi applications). <shrug>

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It's all about fuel atomization guys.......

 

for a carbureted engine, a slightly rough surface on the intake ports promotes turbulent flow which tends to keep the fuel mixed with the air in the intake. if you are running big carbs and cam with a lot of fuel delivery, a polished intake can cause puddling of the fuel.....(thats bad...) polishing the intake can be a benefit, but for very specific conditions/applications.

 

I’m with mudge, remove any big casting goobers and your good to go...

 

also, match porting the intake to the head can help a lot too.

 

If your really serious about it, find a race shop that can flow bench, extrude hone, etc. your intake manifold, but if your running SUs that’s overkill. Just get triple carbs......

 

unless your running hi compression and a big cam, mods to the intake manifold are not going to give you a lot....

 

good luck,

 

Ian

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