1.5 vs 1.6 Rocker arm ratio
04-30-2008, 02:18 PM
#1
Instructor
Thread Starter
1.5 vs 1.6 Rocker arm ratio
If the Stock L 98 cam -1990 corvette lift is
.413 Intake
.428 Exhaust
with a 1.5 rocker arm ration what would it be with a 1.6 rocker arm ratio?
I am trying to see what the #113 head flow difference would be based on the lift.
.413 Intake
.428 Exhaust
with a 1.5 rocker arm ration what would it be with a 1.6 rocker arm ratio?
I am trying to see what the #113 head flow difference would be based on the lift.
04-30-2008, 02:22 PM
#2
Tech Contributor
If the numbers you quote above are at the valve, divide by 1.5 and then multiply by 1.6. If the numbers above are the camshaft lift numbers, just multiply.
04-30-2008, 03:32 PM
#3
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Also, remember that the stock rockers arms, even though they are rated at 1.5, are probably less than that. So going with after-market 1.6 rockers will actually give more of an effective valve lift.
From what I've read, stock rockers are more likely in the area of 1.45
Jake
From what I've read, stock rockers are more likely in the area of 1.45
Jake
04-30-2008, 03:45 PM
#4
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Most specs are quoted with 1.5s, divide by 1.5 to get the lift of the cam. The specs you have there are with 1.5s.
Then multiply by whatever rocker ratio you want to run.
04-30-2008, 06:37 PM
#8
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You cant just add .030.It doesnt work like that.
If you have .500 lift with a 1.5,a 1.6 would add .33 and give you .533
A .600 lift with 1.5,a 1.6 would add .40 giving you .640 lift.
.413 lift with a 1.5,a 1.6 would give you .440,adding .27 of lift.
You have to take the lift number with 1.5 and divide it by 1.5,then multiply by 1.6.
.413 divide by 1.5=.275,now multiply by 1.6=.440
You just cant add .030 to any lift if your going to 1.6.
If you have .500 lift with a 1.5,a 1.6 would add .33 and give you .533
A .600 lift with 1.5,a 1.6 would add .40 giving you .640 lift.
.413 lift with a 1.5,a 1.6 would give you .440,adding .27 of lift.
You have to take the lift number with 1.5 and divide it by 1.5,then multiply by 1.6.
.413 divide by 1.5=.275,now multiply by 1.6=.440
You just cant add .030 to any lift if your going to 1.6.
04-30-2008, 07:16 PM
#9
Safety Car
Just take the lift, divide by 1.5, then multiply that amount by 1.6 to get the new lift number. And of course it doesn't effect the duration.
04-30-2008, 07:54 PM
#10
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Originally Posted by flatbush862
If the Stock L 98 cam -1990 corvette lift is
.413 Intake
.428 Exhaust
with a 1.5 rocker arm ration what would it be with a 1.6 rocker arm ratio?
I am trying to see what the #113 head flow difference would be based on the lift.
.413 Intake
.428 Exhaust
with a 1.5 rocker arm ration what would it be with a 1.6 rocker arm ratio?
I am trying to see what the #113 head flow difference would be based on the lift.
RACE ON!!!
04-30-2008, 07:57 PM
#11
Instructor
Thread Starter
87L98Z52 calculated correctly above.
So from your website (below) :
Here are some intake flow numbers for #113 heads from TPIS "Insider Hints":
Lift......Stock......Ported
.100"......62...........68
.200".....116.........149
.300".....161.........193
.400".....185.........211
.500".....195.........211
.600".....198.........211
Note that the "Ported" numbers were with 1.940" intake valves.
That would put the intake flow @ 189cfm - correct??
