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Cam recommendations? Twin Turbo
#2774200
05/13/20 01:11 PM
05/13/20 01:11 PM
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Joined: Dec 2003
Posts: 2,586
Illinois, Indiana, Louisiana
ProStDodge
OP
master
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OP
master
Joined: Dec 2003
Posts: 2,586
Illinois, Indiana, Louisiana
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I have been off this board for some time now, but starting to make progress again. .
I am finally building the motor for my "street" car superbird and I was hoping to get advise on cam and lifters for it.
I have a mega block from a 500" 505hp crate motor. (4.15 x 4.380), and a set of Indy CNC 325 heads. It comes out to a 8.8 compression ratio with the rods and pistons I have for it.
The plan is twin 74mm turbos, keeping the boost around 15-18 max.
This will be street driven more than raced.
The heads came with 1.5 rockers, springs have 534# @ .500 and 597# @ .600, 256# seat. 2" installed.
I seem to recall that the mega block needs a particular lifter to clear the boss.
Thanks in advance!
Scott
Last edited by ProStDodge; 05/13/20 01:14 PM.
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Re: Cam recommendations?
[Re: ProStDodge]
#2774205
05/13/20 01:18 PM
05/13/20 01:18 PM
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Joined: Dec 2004
Posts: 10,552
Rittman Ohio
fourgearsavoy
I Live Here
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I Live Here
Joined: Dec 2004
Posts: 10,552
Rittman Ohio
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When I was looking for a cam this year I went to the Howard's Cams web site and plugged in all my specs to their order form and I couldn't believe how good my car runs with their recommendations. I don't know what software they use but it just flat out work awesome. Gus 
64 Plymouth Savoy
493 Indy EZ's by Nick at Compu-Flow
5-Speed Richmond faceplate Liberty box
Dana 60
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Re: Cam recommendations? Twin Turbo
[Re: ProStDodge]
#2774220
05/13/20 02:08 PM
05/13/20 02:08 PM
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Joined: Jan 2005
Posts: 2,540
Milwaukee WI
TRENDZ
master
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master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
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Your first cam should be a wide-ish lsa. 112-116 range
Duration in the mid 230-240 range.
The reason I say first cam, is the cam timing is heavily dependent on intake / exhaust pressure ratios. It isn’t really a calculable figure without trying it to get a base line. Any cam will function. But getting one that works great is only found through trial and error. Instead of just getting cam and converter correct, you throw in a 3rd variable with the turbos. The nice thing is, even a bad turbo combination will be way better than any well thought out N/A combo.
Last edited by TRENDZ; 05/13/20 07:40 PM. Reason: Additional thoughts...
"use it 'till it breaks, replace as needed"
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Re: Cam recommendations? Twin Turbo
[Re: ProStDodge]
#2774558
05/14/20 03:36 PM
05/14/20 03:36 PM
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Joined: Jan 2003
Posts: 5,484
SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,484
SoCal
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I have been off this board for some time now, but starting to make progress again. .
I am finally building the motor for my "street" car superbird and I was hoping to get advise on cam and lifters for it.
I have a mega block from a 500" 505hp crate motor. (4.15 x 4.380), and a set of Indy CNC 325 heads. It comes out to a 8.8 compression ratio with the rods and pistons I have for it.
The plan is twin 74mm turbos, keeping the boost around 15-18 max.
This will be street driven more than raced.
The heads came with 1.5 rockers, springs have 534# @ .500 and 597# @ .600, 256# seat. 2" installed.
I seem to recall that the mega block needs a particular lifter to clear the boss.
Thanks in advance!
Scott What fuel? Intercooler?
Brian Hafliger
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Re: Cam recommendations? Twin Turbo
[Re: TRENDZ]
#2774725
05/15/20 06:39 AM
05/15/20 06:39 AM
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Joined: Aug 2005
Posts: 759
Southington Ct.
turbobitt
super stock
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super stock
Joined: Aug 2005
Posts: 759
Southington Ct.
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Your first cam should be a wide-ish lsa. 112-116 range
Duration in the mid 230-240 range.
The reason I say first cam, is the cam timing is heavily dependent on intake / exhaust pressure ratios. It isn’t really a calculable figure without trying it to get a base line. Any cam will function. But getting one that works great is only found through trial and error. Instead of just getting cam and converter correct, you throw in a 3rd variable with the turbos. The nice thing is, even a bad turbo combination will be way better than any well thought out N/A combo. This advice s right on the money. With the back pressure in the exhaust due to drive pressure, the exhaust closing @ .050 should be before or at TDC but not after. Typically will put the cam durations in the low to mid 230's and maybe higher with a modern aggressive lobe profile. LSA typically as mentioned in the 112-116 but leaning toward 114. Cams like this will make power well into the 30 psi range. If the cam gets any bigger and a lot of overlap the drive pressure at the higher boost levels will truncate the power. AG.
Last edited by turbobitt; 05/15/20 06:43 AM.
1970 Challenger w/572 Hemi street car and my pride and joy.
1986 T-Type with 272 Stage 2 Buick V6 engine - True 8 second street car. Just updated the engine and put down 928 HP @ 35# boost to the ground on chasis dyno.
1976 Cee Bee Avenger Jet Boat - 460 Ford powered.
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