More boost or more compression??
Thread Starter
Staging Lane
Joined: May 2005
Posts: 80
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From: michigan
More boost or more compression?? For those that dont know me i have an F1 procharged 350sbc. Last year i built my motor with intentions on running without an intercooler and around 12# boost. In doing so i built my motor at about 7:9:1 compression ratio. I put down 500rwhp and 490rwtq.. This year i decided on purchasing a large OBX FMIC and was wondering if im going to see an increase in power, at the same boost level, due to a substantially cooler air inlet temp?
Furthermore, since i am now running an intercooler i was thinking of increasing my compression ratio to around 9.5.1 but in doing so would need to purchase either new heads or pistons.. My question is as follows; Run more boost or increase compression ratio?? My only concern about choosing to run more boost is that i dont was to blow a head gasket or crack the block. No o-ringed block, just cometic gaskets. Any idea as to how much power can be produced on a 010 chevy block that is studded with aftermarket mains? im guessing about 800hp? It might sound like a dumb question... duhh why spend money on pistons or cylinder heads when u can just up the boost level rite? Correct me if im wrong but isnt there allot more stress on engine components if you had a motor producing 800hp with 7.1 compression at 20lbs of boost VS. the same cubic inch motor with a compression ratio of 9.5.1 running 12lbs?? Please be gentle, im still kind of new with the forced induction stuff.
Thanks
Furthermore, since i am now running an intercooler i was thinking of increasing my compression ratio to around 9.5.1 but in doing so would need to purchase either new heads or pistons.. My question is as follows; Run more boost or increase compression ratio?? My only concern about choosing to run more boost is that i dont was to blow a head gasket or crack the block. No o-ringed block, just cometic gaskets. Any idea as to how much power can be produced on a 010 chevy block that is studded with aftermarket mains? im guessing about 800hp? It might sound like a dumb question... duhh why spend money on pistons or cylinder heads when u can just up the boost level rite? Correct me if im wrong but isnt there allot more stress on engine components if you had a motor producing 800hp with 7.1 compression at 20lbs of boost VS. the same cubic inch motor with a compression ratio of 9.5.1 running 12lbs?? Please be gentle, im still kind of new with the forced induction stuff.
Thanks
Thread Starter
Staging Lane
Joined: May 2005
Posts: 80
Likes: 0
From: michigan
Originally Posted by Boostaholic
I would leave your compression ratio right where it is and turn the boost up'
Originally Posted by BlownBird68
My question is as follows; Run more boost or increase compression ratio?? My only concern about choosing to run more boost is that i dont was to blow a head gasket or crack the block. No o-ringed block, just cometic gaskets. Any idea as to how much power can be produced on a 010 chevy block that is studded with aftermarket mains? im guessing about 800hp?
Yes, there would be more stress on the engine at 20 psi with your lower compression ratio. Since you already have the engine together, I would up the boost to approx 16 psi and see if you are happy with it. You should not have any problems at the 16 psi level for durability. Bob
It matters what the car is built for.For a street car I would run compression at 9-1 with 12-14lb's but the Cam will also dictate compression/boost.
I figure if it was a race car you would be running an air to water intercooler which we run compression at 10-1 with a big Cam and make 1000+rw.
I figure if it was a race car you would be running an air to water intercooler which we run compression at 10-1 with a big Cam and make 1000+rw.
Thread Starter
Staging Lane
Joined: May 2005
Posts: 80
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From: michigan
Originally Posted by Slowhawk
It matters what the car is built for.For a street car I would run compression at 9-1 with 12-14lb's but the Cam will also dictate compression/boost.
I figure if it was a race car you would be running an air to water intercooler which we run compression at 10-1 with a big Cam and make 1000+rw.
I figure if it was a race car you would be running an air to water intercooler which we run compression at 10-1 with a big Cam and make 1000+rw.
Intercooler i just purchased - OBX 31x12x4 FMIC
How does the cam determine boost?
I'd keep what you have. John Meany has a early C4 that is like 7.9:1 and it runs like 137mph on pump gas and like 160mph on C16. He's a bad ****.
I'd run up the boost. One way to look at it is that you will need to make another lb of boost to make up for a full point drop in compression.
But at the end of the day, if you make more boost than the 9:1 or 10:1 guy, but have lower inlet air temps and coolant temps, your combo is safer.
My current combo is about 8.25:1. It was not worth it to me to run 9.5:1 or more since I don't want my IAT's shooting past like 125F during a pass.
You might be very impressed with how much power you can safely make with pump gas.
I'd run up the boost. One way to look at it is that you will need to make another lb of boost to make up for a full point drop in compression.
But at the end of the day, if you make more boost than the 9:1 or 10:1 guy, but have lower inlet air temps and coolant temps, your combo is safer.
My current combo is about 8.25:1. It was not worth it to me to run 9.5:1 or more since I don't want my IAT's shooting past like 125F during a pass.
You might be very impressed with how much power you can safely make with pump gas.
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From: The point of no return...
Originally Posted by Boostaholic
I would leave your compression ratio right where it is and turn the boost up.
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Originally Posted by BlownBird68
Correct me if im wrong but isnt there allot more stress on engine components if you had a motor producing 800hp with 7.1 compression at 20lbs of boost VS. the same cubic inch motor with a compression ratio of 9.5.1 running 12lbs?? Please be gentle, im still kind of new with the forced induction stuff.
Thanks
Thanks
Originally Posted by BlownBird68
Cam is 242-250 580-600 lift 112 ls1
Intercooler i just purchased - OBX 31x12x4 FMIC
How does the cam determine boost?
Intercooler i just purchased - OBX 31x12x4 FMIC
How does the cam determine boost?
