IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: Tim Hensley on May 17 2015, 11:40:49 PM
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I ask it on the other form thought id ask over here
I have two cams
FT 206-210 and a DLS 210-210
My new combo netted 8.2 to 1 compression ratio (Old was 9to 1)compression ratio is all that changed
Champion CNC Irons and intake
5857 BB S cover
2800 LU EA stage II
Both cams will get me to my 11.5 ET
Dose one cam work better with lower compression than the other
dose one have a flatter TQ curve
Both cams got me in the 11.s DLS with less boost 20lb FT 25lb ,not fair to compare different heads with FT 206-210
DLS cam EX and LS is way different than FT EX and LS
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If you have the cam cards and some other info on the build you can figure out the dynamic compression ratio (DCR). Even though the 2 cams are close in specs duration @ .050 - they might have completely different valve events. If you can run them thru a DCR calc it might show which one will be more responsive off boost.
My guess is you probably wouldn't notice much difference between the 2 - but I haven't seen the cam cards either.
Steve will recommend trying to get the compression back to 9:1 - and I agree :)
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Yep....
side note, it takes the same hp to run 11.5 so the lower boost required is not all that meaningful. It takes combustion heat to make hp so while one may require less boost, there are still the same number of air molecules in the combustion chamber so the stress on the engine is the same-in other words, there is no free lunch and the stress on the engine is the same.
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Cylinder pressure is cylinder pressure - most of the time more is better, until it's too much :rofl:
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there was a communication err on my part,I thought I said 9 to 1,but im not going to bash no one but myself,its built shipped and I have to live with it.
Ill run it through the DCR calc.Timing is different on the two cams ill get back with the #
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This is FT cam
Static compression ratio of 8.2:1.
Effective stroke is 3.20 inches.
Your dynamic compression ratio is 7.72:1 .
Your dynamic cranking pressure is 151.78 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 25 PSI is 20.85 :1.
DLS cam
Static compression ratio of 8.2:1.
Effective stroke is 3.15 inches.
Your dynamic compression ratio is 7.61:1 .
Your dynamic cranking pressure is 148.97 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 25 PSI is 20.55 :1.
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probably will not be able to tell the difference but I would go with the first one just on scientific principles
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Tim can you play with the numbers and advance the cam(s) 2 and 4 degrees and see what the nets.
That might get it up some.
Steve how far can you push the DCR on pumpgas with cast iron headed LC2?
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Don't know...I run 9.2-1 static on both my cars. One has the stock cam and the other one has a 210/210 roller but I don't have the cam card any more. Both have iron heads.
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Ill run the #
My DLS is +2 know ,I never see DLS cams advertise so Im trying to keep it low keyed
is your 210-210 a DLS ? I have my card and would send you a copy
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That's the reason cam manufacturers ''grind'' their cams advanced. To make up for people killing the dynamic compression with intake lobes that are too fat.
When it comes to cams, bigger is hardly ever better. You want just enough lobe to do the job and nothing more.
With us, we get to cheat. Compressed air is smaller than atmospheric air. Our molecules can follow curves, flow through ports, and squirt past valves much easier with up to 3 times the pressure of the atmosphere helping out.
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Remember one thing. If you're not willing to put the boost to it...then the kid in the next lane with a Honda and a big fart can on it is gonna beat yer' ass. Won't matter what cam you have in it. I see so many guys spending wads of money on turbos and only running 20 lbs of boost. They won't run any higher boost pressure cuz they haven't got the balls to max the turbo out. Like Earl says...a bigger cam ain't always better. Time in my sig is with a flat tappet off the shelf 212/212 Comp Cams POS...and a little 62 turbo. :)