Re: Dyno results, not good
Posted: Thu Jul 12, 2018 3:48 pm
Id take it out.
I pulled mine out not long back. Only to change a split coolant pipe but easier with engine out.
The job is a long day or a weekend depending on how often the kids demand attention. Hardest part was undoing the exhaust.
I ran some boring simple maths, lift/valve diam.
360?1.5625=0.2304
What this means is less than 0.25 and its the valve seat area/throat/venturi, that is the primary obstruction for air flow.
You could measure the hole and see what the difference is as a percentage of intake valve diam. In theory the hole should be 85 to 90% of the valve, or a simple check is about the same size as your exhaust valve.
If its smaller you may be getting a restriction in which case id reccomend a clean up of this area and valve angles cut to suit low lift bias.
It also means fitting a bigger cam would be wasted unless that porting was done. Incidently a 0.450 lift gives 0.288 so would need work further up the port to suit. This then gets into cross sectional areas as the port itself may become restrictive sooner than the valve seats.
Off course all the above may be of no relevence, it may just need a good setting up.
I pulled mine out not long back. Only to change a split coolant pipe but easier with engine out.
The job is a long day or a weekend depending on how often the kids demand attention. Hardest part was undoing the exhaust.
I ran some boring simple maths, lift/valve diam.
360?1.5625=0.2304
What this means is less than 0.25 and its the valve seat area/throat/venturi, that is the primary obstruction for air flow.
You could measure the hole and see what the difference is as a percentage of intake valve diam. In theory the hole should be 85 to 90% of the valve, or a simple check is about the same size as your exhaust valve.
If its smaller you may be getting a restriction in which case id reccomend a clean up of this area and valve angles cut to suit low lift bias.
It also means fitting a bigger cam would be wasted unless that porting was done. Incidently a 0.450 lift gives 0.288 so would need work further up the port to suit. This then gets into cross sectional areas as the port itself may become restrictive sooner than the valve seats.
Off course all the above may be of no relevence, it may just need a good setting up.