Back pressure vs cam, anyone tested?
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Joined: Oct 2005
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From: Belleville, IL
Back pressure vs cam, anyone tested? I am looking at a more aggressive cam for my V6.
I have been reading a lot of things, it seems if i monitor the back pressure that would tell me how aggressive i can get with the cam profile
Has any one done this on any turbo setup? what were your findings?
It seems the less back pressure you have you can get away from split duration 235/225 and run 235/235 or run even l split 235/245
any input welcome
current cam 224/215 116*LSA
I have been reading a lot of things, it seems if i monitor the back pressure that would tell me how aggressive i can get with the cam profile
Has any one done this on any turbo setup? what were your findings?
It seems the less back pressure you have you can get away from split duration 235/225 and run 235/235 or run even l split 235/245
any input welcome
current cam 224/215 116*LSA
Last edited by Turbo V6 Camaro; Apr 10, 2009 at 04:48 AM.
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Joined: Jul 2005
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The theory is that the higher the backpressure, the more "different" the cam needs to be than NA. So, if the backpressure is 1:1 with boost, you'd cam it just like you would an NA motor. However, my backpressure is 2:1, but my 224/236 works quite well.
I also have this crazy theory that the cam somewhat determines backpressure. For starters, the higher you rev an engine, the higher the backpressure goes. Secondly, a lot of overlap will "even out" the pressure by allowing reversion from exhaust to intake.
Mike
I also have this crazy theory that the cam somewhat determines backpressure. For starters, the higher you rev an engine, the higher the backpressure goes. Secondly, a lot of overlap will "even out" the pressure by allowing reversion from exhaust to intake.
Mike
The theory is that the higher the backpressure, the more "different" the cam needs to be than NA. So, if the backpressure is 1:1 with boost, you'd cam it just like you would an NA motor. However, my backpressure is 2:1, but my 224/236 works quite well.
I also have this crazy theory that the cam somewhat determines backpressure. For starters, the higher you rev an engine, the higher the backpressure goes. Secondly, a lot of overlap will "even out" the pressure by allowing reversion from exhaust to intake.
Mike
I also have this crazy theory that the cam somewhat determines backpressure. For starters, the higher you rev an engine, the higher the backpressure goes. Secondly, a lot of overlap will "even out" the pressure by allowing reversion from exhaust to intake.
Mike
Thread Starter
11 Second Club
Joined: Oct 2005
Posts: 253
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From: Belleville, IL
are you running "header type" or "log type" ?
Two things:
1. did it affect spool between the cams?
2. did the cams affect back pressure (did you test? I assume not? )
3. would larger hot side rduce the back pressure to alow the other cam to run? or would the more lag not be worth it even if it made more power?
any more data/input please post
i'm thinking of a 235/242 at 115 LSA if my back pressure is in check
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Joined: Jul 2005
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that the data i'm looking for, i know it's apples to planets but the physics should stay the same i just have 2 less bang rooms
are you running "header type" or "log type" ?
Two things:
1. did it affect spool between the cams?
2. did the cams affect back pressure (did you test? I assume not? )
3. would larger hot side rduce the back pressure to alow the other cam to run? or would the more lag not be worth it even if it made more power?
any more data/input please post
i'm thinking of a 235/242 at 115 LSA if my back pressure is in check
are you running "header type" or "log type" ?
Two things:
1. did it affect spool between the cams?
2. did the cams affect back pressure (did you test? I assume not? )
3. would larger hot side rduce the back pressure to alow the other cam to run? or would the more lag not be worth it even if it made more power?
any more data/input please post
i'm thinking of a 235/242 at 115 LSA if my back pressure is in check
2. That was before my backpressure-testing days, but it was probably lower with the 224/236 cam.
3. On LT1's, the 224/236 is a good NA cam. So, lowering the backpressure should theoretically only make this cam work better.
Sorry for the lack of data. I tried the 226/226 cam a long time ago and was disappointed so I put my old "supercharger cam" back in it and quit listening to "common logic" on turbo cams.
Mike
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Joined: Mar 2006
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From: australia
yeep from a 355sbc v8 tho
engine on dyno , twin 57mm turbonetics
cam 1 : 237/237 @ 114 with .509 total lift , installed @ 110 intake centre line
cam 2 : 256/245 @ 114 with .510 total lift , installed @ 110 intake centre line
Cam 2 made MORE power for same boost, more torque for higher into rpm range. back pressure was less , higher up in rpm range.
these where flat tappet cams.
258/258 @ 114 roller ....now thats a different story all together....
ash
engine on dyno , twin 57mm turbonetics
cam 1 : 237/237 @ 114 with .509 total lift , installed @ 110 intake centre line
cam 2 : 256/245 @ 114 with .510 total lift , installed @ 110 intake centre line
Cam 2 made MORE power for same boost, more torque for higher into rpm range. back pressure was less , higher up in rpm range.
these where flat tappet cams.
258/258 @ 114 roller ....now thats a different story all together....
ash
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