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header size matters?
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http://www.clubcobra.com/forums/keith-craft-racing/89053-header-size-matters.html)
| tuska |
07-05-2008 06:47 PM |
header size matters?
Hi,
i can get 1 7/8"primarys premade or should i get specially made 2" primarys . As there's not much restriction in the rest of system will it make a difference on my kc 427 sbf as i've been told full length under body pipes make better power anyway?
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| BossCER |
07-05-2008 07:10 PM |
tuska,
That is a great question for your engine builder. I am sure he would have an opinion.
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I have watched a few episodes of Horsepower TV (SPIKE) where they dyno test different products including headers. Size, length, bends and other factors do make a difference. Nothing major from what I remember but definately worth picking the right size, etc. I think you can watch (Buy) episodes from iTunes.
BossCer's comment was good. Match the headers with the engine for the best effect.
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| WildThing |
07-05-2008 10:35 PM |
1 7/8" will be fine. The air flow will be more than enough. If you are trying for a world record in some event that nobody cares about then I would suggest that you go for 2".
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| Keithc8 |
07-05-2008 11:18 PM |
The 1 7/8 will be fine for what you are doing. You want to make sure they are not blocking the parts at the head opening. The next restriction will be the sidepipe muffler size. I have seen some of these as small as 1 1/2 and that really restricts the Hp as well. Thanks, Keith Craft
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| CHANMADD |
07-06-2008 12:29 PM |
Primary pipe diameter and length do make a difference.I suggest looking up various dyno runs on similar motors to yours.You will get an idea as to what would be best.The 17/8 sounds big enough to me (thats what I run). The same as intake runner length makes a diffs so does the exhaust dimensions. Bigger is not necessarily better,.....in this case...anyway!
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| Great Asp |
07-06-2008 01:50 PM |
Quote:
Originally Posted by Keithc8
(Post 858570)
The 1 7/8 will be fine for what you are doing. You want to make sure they are not blocking the parts at the head opening. The next restriction will be the sidepipe muffler size. I have seen some of these as small as 1 1/2 and that really restricts the Hp as well. Thanks, Keith Craft
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This is what I have found to be true.
Using the 205 AFR heads, the standard SPF headers blocked part of the exaust ports and hurt hp.
2" SS headers were opened up at the exaust ports and helped hp (45hp) Grinding the blocked part on the 1-7/8" will do the same.
Work on the mufflers.
E |
| tuska |
07-07-2008 07:14 PM |
I'll look into mufflers as sugested...literally !! And port match the manifold plates to the head. cheers glen
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| Red S/C |
07-07-2008 07:39 PM |
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| tuska |
07-14-2008 01:16 AM |
Are your spiral baffles similar Db to glass packed side pipes or do they have a tone of their own?
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| Traveller |
07-14-2008 10:08 AM |
What about no mufflers? Least restrictive. The downsides are your neighbors hate you and your neighbors 3 blocks over hate you.
I took mine out for a test drive before tearing i all down and I'm still grining. :)
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| cobrarkc |
07-30-2008 09:51 AM |
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| 427 S/O |
07-30-2008 01:14 PM |
Someone told me to come off the block at least three inches before making the first bend, not sure it matters but I did it when I made mine?.
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