What makes a cam SD compatible?
Thread Starter
2nd Gear Member
Joined: Aug 2008
Posts: 350
From: New York
What makes a cam SD compatible?
as the title says, what characteristics of a cam makes it SD compatible, i know SD needs to stay in a certain range of vaccum to function
so what cam characteristics will decide how much vaccum it can pull to make it SD friendly
so what cam characteristics will decide how much vaccum it can pull to make it SD friendly
3rd Gear Member
Joined: Dec 2007
Posts: 652
From: buckeyelake ,ohio
the lsa of the cam is the key and duration . ultimately a 114 degree lsa is the only type to run ND 275 duration is about max with sd but running it you will have to do a few things to get it to work right .
3rd Gear Member
Joined: Dec 2007
Posts: 652
From: buckeyelake ,ohio
http://us.lrd.yahoo.com/_ylt=Aq_Zn6w...2D4E1C1795.gif
this chart will show what cams work with sd with little to no mod work .
this chart will show what cams work with sd with little to no mod work .
Joined: Jun 2008
Posts: 38
From:
Here are 6 cams that should work with Speed Density N/A use.
Look at there application discriptions and match to your desired use.
The cams with the longer durations of course will exibit some small amount of lower end torque loss until the engine gets into the cam's rpm range as specified by the mfger.
This can be offset with higher stall convertor and/or lower rear gear ratios that allows the engine to get to the cam's range quicker.
SD compatable CAMS.
Crower 15510.
Crower 15511.
Comp. Cams #35-308-8 (266HR).
Comp. Cams #35-310-8 (270HR).
Crane #444211 (Power Max 2020).
Crane #444221 (Power Max 2030).
Notes; The Crower 15511 is about the longest duration that can be used and will degrade drivability somewhat but often can be tuned around if your willing to go to those lengths for performance.
Looking at cam cards; the intake opening and exhaust closing points are the indicators of overlap.
When you see an intake closeing spec ATDC and an exhaust closing BTDC, you are seeing negitive overlap such that no pump back should occurr. That should make the cam SD friendly.
Pay attention to the mfger's discription per your application and above all 'believe what they say' about the RPM range of the cam and the reccomended valve springs and rocker ratios to use.
Final notes are that the larger lobe seperations don't mean the cam is poor on power as compaired to the lower seperations. The greatest differences are on how wide the average power band is developed as opposed to narrow bands that are more suited to road racing, circle track and drag use and the type of transmission in use for the applications.
The Corvette uses cam seperations in the 118 range per the front office because they donot want their customers complaining about rough idle. Sound familuar?
Another example is a 110 lobe seperation used in a direct drive single gear car for circle track use. This peticular cam is designed for the highest, broad power curve in a very light race car running between about 4000 to 7800 rpm
Look at there application discriptions and match to your desired use.
The cams with the longer durations of course will exibit some small amount of lower end torque loss until the engine gets into the cam's rpm range as specified by the mfger.
This can be offset with higher stall convertor and/or lower rear gear ratios that allows the engine to get to the cam's range quicker.
SD compatable CAMS.
Crower 15510.
Crower 15511.
Comp. Cams #35-308-8 (266HR).
Comp. Cams #35-310-8 (270HR).
Crane #444211 (Power Max 2020).
Crane #444221 (Power Max 2030).
Notes; The Crower 15511 is about the longest duration that can be used and will degrade drivability somewhat but often can be tuned around if your willing to go to those lengths for performance.
Looking at cam cards; the intake opening and exhaust closing points are the indicators of overlap.
When you see an intake closeing spec ATDC and an exhaust closing BTDC, you are seeing negitive overlap such that no pump back should occurr. That should make the cam SD friendly.
Pay attention to the mfger's discription per your application and above all 'believe what they say' about the RPM range of the cam and the reccomended valve springs and rocker ratios to use.
Final notes are that the larger lobe seperations don't mean the cam is poor on power as compaired to the lower seperations. The greatest differences are on how wide the average power band is developed as opposed to narrow bands that are more suited to road racing, circle track and drag use and the type of transmission in use for the applications.
The Corvette uses cam seperations in the 118 range per the front office because they donot want their customers complaining about rough idle. Sound familuar?
Another example is a 110 lobe seperation used in a direct drive single gear car for circle track use. This peticular cam is designed for the highest, broad power curve in a very light race car running between about 4000 to 7800 rpm
2nd Gear Member
Joined: Aug 2008
Posts: 180
From: Georgia
The cam in a stock 5.0 CAN propel a stang into the upper 11's. Are you looking to go beyond that? If so, you won't be SD anymore. I JUST read an article today in, another forum, that was talking about cam size. If I can fine it again, I'll post it. I doooo love the sound of a cam though...
Joined: Mar 2008
Posts: 15
From: Northwest Indiana
Might want to check out Thumper of Orange County first- they port stock heads, like mine, and perform other 5.0 miracles, before buying a cam. Loads of info from them, Stangnet Thumper460, pm them with any questions.