Twin 70mm or 76mm spool on 5.3 on the street?
01-05-2013, 10:03 AM
#22
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I wasn't asking for myself I was just going along with the topic from the first post..
Theres no other way for this to sound but *******'ish... so please dont take it that way...
Best cam will be the one designed for the combination as a whole.
You just gave me a pair of turbos... and im assuming your meaning on a 5.3 application...
I can say with certainty it wont be a reverse grind. Lol.... unless you wanna put em on a 427.....
Generally... twin cams can be made much more aggressive on the exhaust events. This does normally take away torque below peak... BUT with energy diverted to the turbine by opening the exhaust valve early without fear of choking the turbine.... we get a very aggressive boost curve that more than makes up for the torque we lost N/A from opening it so early.
The upper limit for your overlap goes up too. It will tolerate more... just depends on other parameters how much you use.
Converters for twins can normally be a tick tighter than for a bigger single capable of the same power.
Jon's combo uses a stock 5.3 shortblock with an LS9 cam installed 2 degrees advanced. 317 heads and a Holley Hi ram. Its a 4000 pound truck with a 390/45/15 tire,3.42 gear and an 80E. It flat hauls the mail.
He ordered a cam from me today.... back to back dyno testing will be done and ill post the cam specs and results once Jon gets the time to do this.
Best cam will be the one designed for the combination as a whole.
You just gave me a pair of turbos... and im assuming your meaning on a 5.3 application...
I can say with certainty it wont be a reverse grind. Lol.... unless you wanna put em on a 427.....
Generally... twin cams can be made much more aggressive on the exhaust events. This does normally take away torque below peak... BUT with energy diverted to the turbine by opening the exhaust valve early without fear of choking the turbine.... we get a very aggressive boost curve that more than makes up for the torque we lost N/A from opening it so early.
The upper limit for your overlap goes up too. It will tolerate more... just depends on other parameters how much you use.
Converters for twins can normally be a tick tighter than for a bigger single capable of the same power.
Jon's combo uses a stock 5.3 shortblock with an LS9 cam installed 2 degrees advanced. 317 heads and a Holley Hi ram. Its a 4000 pound truck with a 390/45/15 tire,3.42 gear and an 80E. It flat hauls the mail.
He ordered a cam from me today.... back to back dyno testing will be done and ill post the cam specs and results once Jon gets the time to do this.
01-05-2013, 02:41 PM
#23
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My On3's have just a very short amount of lag but well worth it. They absolutely destroy the performance that my twin 62's did. I have ran 25lbs of boost with no issues so far. Mine has a .68 ar. I will post 2 videos. The first is with the 62's and you can definitely tell it spools faster but I also hit the rev limiter faster. The second vid is of the 70's. A little lag but definitely PULL way harder...not even close!
62's and 3.90's
70s and 3.42 gears
70's in car showing 25-30lbs of boost.
62's and 3.90's
70s and 3.42 gears
70's in car showing 25-30lbs of boost.
01-05-2013, 05:28 PM
#24
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Do you have a link to the build?
01-06-2013, 05:43 PM
#26
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Here is a video leaving off idle on the street. I stalled it up to 1000-1100rpm for a second then nailed it.
http://youtu.be/5M3wJfB4mAI
http://youtu.be/5M3wJfB4mAI
