How hard can I rev my motor
- Thread starter albanygt40
- Start date
Until you see smoke!:thumbsup:
Seriously, I would try to stay under 6000 with stock internals. 5500 is better. That just my opinion but it is cheaper to error on the safe side.
Seriously, I would try to stay under 6000 with stock internals. 5500 is better. That just my opinion but it is cheaper to error on the safe side.
Howard Jones
Supporter
I have seen some chassis dyno charts of HO 302 's in mustangs. I believe these have the iron heads and a pretty mild cam. They are making about 230Hp at the wheels.
Anyway they completely run out of steam at about 5000 revs. The power curve just drops right through the floor starting at 4600 or so.
People tell me that it is a combination of cam timing, head flow, CR, and valve springs with the first recommended change being springs. The stock springs just don't have enough opens seat pressure to control the valves much beyond 5000 revs. This along with the cam and small valves in the iron heads pretty much limit the effective power band to less than 5000.
I have a 345HP alum head SVO 302 in my car. It has had a little pocket porting and 1.94 1.54 valves in them with stock springs (same as yours). The headers are as free flowing as can be done with mufflers and I am running a 750 DP Holley and RPM performer intake. The MSD dis and spark box are set to have the advance all in, 34 degrees, at 2400 RPMs. On the same chassis dyno I am making 294HP at a little bit above 5100 revs. At 5600, it is down to 250HP. The engine has been very carefully ballanced with a steel crank, ARP rod bolts on stock rods and pistons reringed with good rings. CR is right at 9.1 to 1.
I shift at 5300 and set limiter to 6000. It's faster that way. In your case I would limit revs to 5000 and shift just before the limiter comes on.
Beware the stock valve springs above 5500 and the stock rod bolts above 6000. Spinning it up it beyond that with a stock ballance job is asking for it. If a rod bolt goes, kiss it all goodby.
Anyway they completely run out of steam at about 5000 revs. The power curve just drops right through the floor starting at 4600 or so.
People tell me that it is a combination of cam timing, head flow, CR, and valve springs with the first recommended change being springs. The stock springs just don't have enough opens seat pressure to control the valves much beyond 5000 revs. This along with the cam and small valves in the iron heads pretty much limit the effective power band to less than 5000.
I have a 345HP alum head SVO 302 in my car. It has had a little pocket porting and 1.94 1.54 valves in them with stock springs (same as yours). The headers are as free flowing as can be done with mufflers and I am running a 750 DP Holley and RPM performer intake. The MSD dis and spark box are set to have the advance all in, 34 degrees, at 2400 RPMs. On the same chassis dyno I am making 294HP at a little bit above 5100 revs. At 5600, it is down to 250HP. The engine has been very carefully ballanced with a steel crank, ARP rod bolts on stock rods and pistons reringed with good rings. CR is right at 9.1 to 1.
I shift at 5300 and set limiter to 6000. It's faster that way. In your case I would limit revs to 5000 and shift just before the limiter comes on.
Beware the stock valve springs above 5500 and the stock rod bolts above 6000. Spinning it up it beyond that with a stock ballance job is asking for it. If a rod bolt goes, kiss it all goodby.
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Ron Earp
Admin
I'm with Howard.
I've owned a few 302 Mustangs and with the stock cam about 5k is all it wants. The valve gear is generally good for 6k tops. But from 5-6k all you're doing is making more noise. If you have E7 head castings, non-ported, with the stockish cam then 5k is all you need to do no matter what the induction.
If you have E7s toss them in the can and get another set of heads and cam.
R
I've owned a few 302 Mustangs and with the stock cam about 5k is all it wants. The valve gear is generally good for 6k tops. But from 5-6k all you're doing is making more noise. If you have E7 head castings, non-ported, with the stockish cam then 5k is all you need to do no matter what the induction.
If you have E7s toss them in the can and get another set of heads and cam.
R
Ford limits a stock 5.0 with EFI to 6250 RPM, when it cuts the fuel to the injectors. With a stock cam and heads, about 4500 is about all you will see before the power starts to drop off. If you are carb'd, there are some tricks to get a little more RPM out of them, but the heads and cam will need to be able to take advantage of the additional RPM. But if using a stock block and internals to be safe, stay below 6200.
