d15b8 to d15b7
#2
10-25-2012, 10:13 AM
is a 12-valve D15B7 possible?
[firstly, if this appears in wrong forum when would a moderator please re-locate the new thread to the appropriate forum? couldn't seem to do it on my own]
1995 Civic CX hatchback, 40/45mpg, stock 8-valve 'D15B8' engine, 'PM8-2' head.
Objective: remove the 8-valve head, replace w 16-valve d15b7 head BUT FIRST remove four intake rocker arms from the b7 head, yielding an operational 12-valve engine. A "d15b12". Basically I want the head to look like a D15B8 w double the exhaust valves.
Goal: increase exhaust flow while maintaining highest fuel economy.
In other words, I want to keep my engine as stock as possible - just want to add four exhaust valves to my existing engine, with the idea being that it'll achieve better efficiency, increased power, or both.
As opposed to my 8-valve head, if a "12-valve" head will yield more power then good, more MPGs then great, but the primary concern is to avoid any efficiency loss (or mechanical problems obviously). If this 8valve-to-12valve swap project will adversely affect the car's MPGs then I won't do it. Car gets 45mpg hwy and the only change in that number I want is a higher change, whether it's an increase in economy (preferred) or performance.
Details: remove 16-valve head from working d15b7 engine. remove 4 intake rocker arms, yielding 4 of 8 valves in perpetually closed position.
Questions:
1. the b7 & b8 are the exact same engine except for the number of valves, right?
2. does anyone know of any reason why removing 4 of 8 intake rocker arms from a d15b7 head won't work?
3. should I swap in the b8's intake rocker shaft? rocker arms? no need to, right?
4. want to keep the original CX's B8 intake manifold. any problem with that? will the ports mate without an uneven manifold-head match issue? a ridge/drop from b8 manifold to b7 intake ports?
5. do the four unused intake ports need to be closed off? (if yes, then how?)
6. [to retain high MPG] the b8's ecu doesn't need to be replaced w the b7's does it? unless i wanted more than 5800 RPMs (b8's limit is 5800)
7. same distributor, same timing belt, same head gasket?
1995 Civic CX hatchback, 40/45mpg, stock 8-valve 'D15B8' engine, 'PM8-2' head.
Objective: remove the 8-valve head, replace w 16-valve d15b7 head BUT FIRST remove four intake rocker arms from the b7 head, yielding an operational 12-valve engine. A "d15b12". Basically I want the head to look like a D15B8 w double the exhaust valves.
Goal: increase exhaust flow while maintaining highest fuel economy.
In other words, I want to keep my engine as stock as possible - just want to add four exhaust valves to my existing engine, with the idea being that it'll achieve better efficiency, increased power, or both.
As opposed to my 8-valve head, if a "12-valve" head will yield more power then good, more MPGs then great, but the primary concern is to avoid any efficiency loss (or mechanical problems obviously). If this 8valve-to-12valve swap project will adversely affect the car's MPGs then I won't do it. Car gets 45mpg hwy and the only change in that number I want is a higher change, whether it's an increase in economy (preferred) or performance.
Details: remove 16-valve head from working d15b7 engine. remove 4 intake rocker arms, yielding 4 of 8 valves in perpetually closed position.
Questions:
1. the b7 & b8 are the exact same engine except for the number of valves, right?
2. does anyone know of any reason why removing 4 of 8 intake rocker arms from a d15b7 head won't work?
3. should I swap in the b8's intake rocker shaft? rocker arms? no need to, right?
4. want to keep the original CX's B8 intake manifold. any problem with that? will the ports mate without an uneven manifold-head match issue? a ridge/drop from b8 manifold to b7 intake ports?
5. do the four unused intake ports need to be closed off? (if yes, then how?)
6. [to retain high MPG] the b8's ecu doesn't need to be replaced w the b7's does it? unless i wanted more than 5800 RPMs (b8's limit is 5800)
7. same distributor, same timing belt, same head gasket?
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