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Discussion Starter · #1 ·
Any generally accepted method to bench test heads for use under boost?
 

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Supercharged or Turbo...? They both make boost but totally different ..! One needs needs great exhaust flow and the other needs great exhaust speed... Then depending on fuel if using alcohol as fuel, then chamber volume and runner volume will need to be well matched for CI and set up.... Everybody overlooks the exhaust side when they should be looking there more than the intake side...
My 2c
 

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Why does it matter on a supercharged combo anyway ? It's mechanically pushed in and mechanically pushed out. Make it extremely big, don't hit water, put trash can lids in for valves and leave enough material to withstand the heat. :p
 

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Discussion Starter · #9 ·
Why does it matter on a supercharged combo anyway ? It's mechanically pushed in and mechanically pushed out. Make it extremely big, don't hit water, put trash can lids in for valves and leave enough material to withstand the heat. :p
Sorta what I was thinking but seems like there must be more to it.
 

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Sorta what I was thinking but seems like there must be more to it.
When heads are done for superchargers the exhaust port gets hogged out to evacuate the port quickly. This is gonna head down the pathway and argument of larger exhaust valves vs. the maximum intake valve. Flow percentages or I/E ratios.
The was a guy here that swapped out a 1.88 exhaust for 1.94 and went .3 and 3-5 mph faster with the same cam.
The ageless argument is build the best n/a head possible. There was a thread here months ago that entertained for a couple of pages.
When it gets down to precise specifics of port shape and other stuff, it's out of my league. I just don't know enough to go any further technically.
My thoughts on a sbf , if I had the coin would be cleveland heads 2.19/ 1.71 for huge valves/ ports .
 

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Efficiency in a cylinder head is just as critical in blower builds
as it is any other. Maybe more.
Poorly designed heads require more boost that can produce more charge heat etc.

Thing with boosted head port design is expansion rates and velocity
profiles play a huge roll because the larger volume of air/ fuel
your moving and the increased velocity.
Giant ports isn't really the answer although you can use more port
volume compared to an equal N/A build.
Because of the larger volume and associated increased velocities
good port shape is more critical.

Blowers will typically want better ex ports, better shape and
more volume.
It's all about area with the ex.
Flow numbers on ex ports can be VERY misleading.
There's some valve job profiles and area management things
that make power but kill flow numbers on the bench.
Remember area is king.

Intake ports, ... don't know about other shops but I quite often
use wider 50* valve jobs for reliability over a greater number of runs
verses a fragile 55* valve job.
This also can be misleading on the flowbench by hurting
upper lift numbers.
However it'll pay off in reliability.

Hope this helps some.

curtis
 

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You ever done any port work on Victor jr heads?
Yes I have... I beleive I got it go flow with a 2.08" valve 319-321cfm @.650-.700 lift exhaust was in the 220cfm or so... It's an ok head but for blower the exhaust port in not good... Better with any of the trick flow R or HP....
 

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Depending on head that's why blowers benefit more exhaust split. I still use a 2.08 valve in my highports and been 4.70s. People always say that don't work or you can't do that. I could put a larger intake valve in my head and bet it doesn't pickup jack going this fast already at least not with cam I'm using
 
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