170 psi = compression?

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Scamper

Scamper

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A cam I like says I need 170 cylinder psi Does anyone know what compression ratio I need?
 
May be better to link the cam you are looking at and telling us something about the engine, trans, converter and rear gearing.
 
The cam doesn't "need" compression, the cam is what --in a sense-- PRODUCES compression.
 
ok here goes i have looked for a decent 340 reasonable priced (no such thing) I am going to rebuild my stock 360 727 trans tc yet to bought but there is a good deal in my area for a 3500 stall and it looks like I am trading my brother for his 3:91 gears weekend runner and part time drag car is end result.
The cam is comp cams xe284h
 
67Dart273 said:
The cam doesn't "need" compression, the cam is what --in a sense-- PRODUCES compression.
Click to expand...

Yes it does, the cam you pick needs a certain cylinder pressure to work effectively, so you need a certain compression ratio to make this happen, or you can just drop in a "very very" small cam & run it with 8.1 compression & get higher cylinder pressures, this way you can say my cam doesn't need compression it has 145 psi, but it only pulls to 4200 RPM, Hot rod engines don't work that way, otherwize we wouldn't go faster lol.

So you need a "certain" cylinder pressure for a specific cam your wanting to run effectively, in order to do this "IF" you want a decent cam is up the compression ratio for its needs.
 
I realize that I need more compression my question is what compression pistons do I buy that will give me the 170 that I will need and will cast iron work with 170 psi or do I need to buy aluminum heads
I am also waiting on a quote back from Mopac on a stroker kit as he says it will be cheaper in the long run.
 
Scamper said:
ok here goes i have looked for a decent 340 reasonable priced (no such thing) I am going to rebuild my stock 360 727 trans tc yet to bought but there is a good deal in my area for a 3500 stall and it looks like I am trading my brother for his 3:91 gears weekend runner and part time drag car is end result.
The cam is comp cams xe284h
Click to expand...

I ran that cam in my 451 B engine, My cylinder pressure was around 180 psi, That cam produced "ton" of low end torgue, decent mid-range, now this was in a B engine, the compression ratio was 9.73.1, i'm sure that cam will still run great with 170 psi, i'd think a true 9.8.1 should get you there in the 360, it should still run really good with a true 9.5.1 & around 160 psi, i also ran this cam in a .060" 360 with KB190s quench dome (.040"), the cranking pressure was around 195 psi, the compression was 10.3.1, it was a screamer with 4.56 gears, even at 3700 ft. & in a fully dressed 73 Swinger, with me it weighed around 3500 lbs.

Now the quench was much better with the KB190s & the iron 915 heads, It ran just fine on pump premium, so those would be my choice for pistons & that cam.
 
At 9.5:1 can you get away with cast iron on pump gas or were you using aluminum?
Good to hear the cam is a good one. What stall were you using?
Thanks for all the comments so far
 
Scamper said:
At 9.5:1 can you get away with cast iron on pump gas or were you using aluminum?
Good to hear the cam is a good one. What stall were you using?
Thanks for all the comments so far
Click to expand...

yea with a 9.5:1 comp you can probably get away with regular with cast heads...
 
JoeDust451 said:
you need a certain compression ratio to make this happen .
Click to expand...

THIS PART of what you said is absolutely correct. But that is NOT what the op said. You cannot predict cylinder pressure without knowing the cam specs, therefore you cannot say that a cam "needs" so much compression PRESSURE
 
Thanks and I not so patiently waiting for my quote to come in on a 408 stroker with his recommendations.I do know he is recommending aluminum heads.He can get a kit right now for 1600 cdn and we will see what the rest is lol. The hardest part I am dealing with is the 1500 for just the machine work, although 20 years ago I paid 800 so I guess not too bad
 
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