Headers too big??
11-15-2014, 09:31 AM
#21
Registered
Just one of those things people should know.
Somewhere back about ten years ago I get a call from a engine / dyno shop to help tune a motor they have. Motor made good power on the dyno but seems lazy in the boat. 502 with blah, blah, blah parts. Okay, not blah, but your typical 550-575hp parts. Custom carb was being blamed and they where chasing there tails. That's why i was called (not a hero call....I know them and they figured another brain would be good.)
once looking at it and all the normal stuff, i ask about the headers. "i don't know was the answer." Which like in this thread is the answer I get almost 100% of the time. "used Stellings" was all they knew.
They where double walled (water cooled of course) and looked big anyway.
So, they fought and thought, fought and thought, about pulling them off.
I left.
Get a call some days later.
2 1/2" ID headers.
Wholly schit !!!!!!!!!
Found some used KE's and they said they got the carb tuned in easy (back to original paramters) and boat ran " the Nuts !"
That's exhaust for you.
If you don't know what you have, then you can't diagnose or understand what you have.
Plain and simple.
Somewhere back about ten years ago I get a call from a engine / dyno shop to help tune a motor they have. Motor made good power on the dyno but seems lazy in the boat. 502 with blah, blah, blah parts. Okay, not blah, but your typical 550-575hp parts. Custom carb was being blamed and they where chasing there tails. That's why i was called (not a hero call....I know them and they figured another brain would be good.)
once looking at it and all the normal stuff, i ask about the headers. "i don't know was the answer." Which like in this thread is the answer I get almost 100% of the time. "used Stellings" was all they knew.
They where double walled (water cooled of course) and looked big anyway.
So, they fought and thought, fought and thought, about pulling them off.
I left.
Get a call some days later.
2 1/2" ID headers.
Wholly schit !!!!!!!!!
Found some used KE's and they said they got the carb tuned in easy (back to original paramters) and boat ran " the Nuts !"
That's exhaust for you.
If you don't know what you have, then you can't diagnose or understand what you have.
Plain and simple.
11-15-2014, 09:48 AM
#22
Registered
After Reading this I was curious as to what exactly I'm running. Mine are Stellings 4" dry to the tip with Stellings Dampers "not mufflers" and what seems to measure as 2" primary's. I'm running a 454 with huge cam and compression. I was told when I bought the Boat that he had to close the dampers to gain back pressure to take off. I quickly found out that wasn't the case. My boat is super loud and love it but this setup may be too big for what i'm running now but not for what I want to run later. 496 stroker. What you think?
I personally would be careful playing with changing out what you have. I mean if you were going to strap the engine to a dyno, then it may be worth trying a different header design.
11-15-2014, 10:21 AM
#23
Registered
Yup, 1 7/8" - 2" ID primaries good for most all 454-502's.
Anybody see my program printout and my remark on collector length ?
BTW: I've seen worse than the 28hp loss (I used as an example) just because of collector length being in 'worse length.'
Not only does power go down in those situations but the motor becomes lazy and less sensitive to tuning changes.
Anybody see my program printout and my remark on collector length ?
BTW: I've seen worse than the 28hp loss (I used as an example) just because of collector length being in 'worse length.'
Not only does power go down in those situations but the motor becomes lazy and less sensitive to tuning changes.
11-15-2014, 02:59 PM
#24
Gold Member
Gold Member
11-15-2014, 05:28 PM
#25
Registered
[QUOTE=SB;4219300]Cheap way.
Smush in some Idaho Potatoes. maine potatoes work for the SBC's.
Poke a 3/4" straight hole thru the Potatoe. 1/2" for the Small Blocks.
If you can, stick a kid's handheld multicolored pin wheel in it. You'll get a slight Vortex effect with it.
It Works !
Edit in: Friday PM, doing paperwork at work, so I get real weird. No one take offense. Maybe worry for me a lil. LOL.
http://www.youtube.com/watch?v=HktV2yGtLv8&sns=em
Smush in some Idaho Potatoes. maine potatoes work for the SBC's.
Poke a 3/4" straight hole thru the Potatoe. 1/2" for the Small Blocks.
If you can, stick a kid's handheld multicolored pin wheel in it. You'll get a slight Vortex effect with it.
It Works !
Edit in: Friday PM, doing paperwork at work, so I get real weird. No one take offense. Maybe worry for me a lil. LOL.
http://www.youtube.com/watch?v=HktV2yGtLv8&sns=em
11-15-2014, 06:08 PM
#26
Platinum Member
Platinum Member
Yup, 1 7/8" - 2" ID primaries good for most all 454-502's.
Anybody see my program printout and my remark on collector length ?
BTW: I've seen worse than the 28hp loss (I used as an example) just because of collector length being in 'worse length.'
Not only does power go down in those situations but the motor becomes lazy and less sensitive to tuning changes.
Anybody see my program printout and my remark on collector length ?
BTW: I've seen worse than the 28hp loss (I used as an example) just because of collector length being in 'worse length.'
Not only does power go down in those situations but the motor becomes lazy and less sensitive to tuning changes.
Yup, collector length was been used for years by the bracket drag racers, ad 18" then keep cutting it off in two " increments till you get ur best ET, if the ET drops off ad the 2 " back on LOL, Hell we could afford a dyno test nor were there any close, good stuff, I like the smell of Nitro in the morning
11-16-2014, 08:45 AM
#27
Registered
Then you are all set. 2" would be better, but that's spliiting hairs.
My point is, if they where say 2 1/8", especially 2 1/4" or bigger, than it would not be splitting hairs.
Mild Thunder - you are mentioning mostly manifold system which have no tuning capabilities. They do offer low or no back pressure.
The more overlap your cam has (NA) (.050", .) the more tuned lengths and diameters help. On the flip side, the more 'wrong' lengths and dimaters can hurt.
I was witness to a 28hp gain on a SBC 450hp motor just over collector length.Why so big ? The lower hp length ended up being a 'wrong' length.
Yup, no schit.
Anyway - go run a 600hp 502 NA marine engine in a boat with Gill's or another free flowing manifold system. Then slap on the KE's. You'll see ! Serious.
My point is, if they where say 2 1/8", especially 2 1/4" or bigger, than it would not be splitting hairs.
Mild Thunder - you are mentioning mostly manifold system which have no tuning capabilities. They do offer low or no back pressure.
The more overlap your cam has (NA) (.050", .) the more tuned lengths and diameters help. On the flip side, the more 'wrong' lengths and dimaters can hurt.
I was witness to a 28hp gain on a SBC 450hp motor just over collector length.Why so big ? The lower hp length ended up being a 'wrong' length.
Yup, no schit.
Anyway - go run a 600hp 502 NA marine engine in a boat with Gill's or another free flowing manifold system. Then slap on the KE's. You'll see ! Serious.
11-16-2014, 09:12 AM
#28
We had a blown 509 on the dyno whit stellings when it made just under 750 hp don t know why but we swapped to a set KE and found almost 900 hp all on the same day same conditions we could not believe it just by swapping headers and adjust the carbs due to the better breathing
11-16-2014, 11:05 AM
#29
Registered
150 hp going to smaller headers, this is getting good!
11-16-2014, 11:31 AM
#30
Registered
We had a blown 509 on the dyno whit stellings when it made just under 750 hp don t know why but we swapped to a set KE and found almost 900 hp all on the same day same conditions we could not believe it just by swapping headers and adjust the carbs due to the better breathing
Last edited by mike tkach; 11-16-2014 at 11:34 AM.
