I thought about describing it in percentage as well, but it doesn't seem right to me since it's a dynamic system measured in CFM and has a time unit. Dealing in percentage makes me think of a static situation (which it is when based off of the 360 degrees the cam has). The flow through the valves is constantly varying due to the amount of back pressure present in the exhaust and the amount of pressure coming in through the intake, VE varying with rpm, etc.
Maybe someone could clarify which would be the better way to look at this.
If I understood the idea that you were trying to convey which I thought was to say that it's such a miniscule amount of time, how much of a difference could it possibly make? Maybe I misunderstood.
By presenting it in percentage form, it looks more significant, which it is IMO. Either way you look at it, it's the same thoguh. As ms, it still doesn't account for how open or at what lift the valves are at any point within that .XXms.
__________________ 98Z28CobraKiller 370ci LQ9 + AFR225's + PT88 9.57 @ 142 so far
it'll make more than 27 psi...been in the 30s at 45 psi co2
__________________ 1999 Pewter T/A | Just another slow drag radial car (see here) Virginia Speed 366ci LS2 + big turbo (the little block that could) | 7.99 @ 177.8 (1.36)
Virginia Speed 388ci LS2 + bigger turbo | In Progress
Special Thanks to TheOutlaw1, Phil99vette, Shawn @ Va Speed and MADMAN for all their help
explain the 48.5 lbs of spring to hold the wg closed...
Like Zombie said, it's not that easy to figure out based on spring and pressure supplied. You have to know all the internal geometry of the WG as well as the exhaust pressure, which defeats the purpose of doing the calcs.
It is pretty easy to measure backpressure, though.
Mike
__________________ 1995 Z28
388 LT4, AFR 210's, Home built T-76GTS turbo system
TH-350, Vigilante 10.5", Ford 9"
In all fairness, you're probably running turbo's that approach 1:1 exhaust:intake pressure. In those cases, you basically cam it as though it's naturally aspirated because the dynamics are nearly the same.
I've never seen an auto drag car with a 1-1 pressure ratio.they are way to lazy to spool.even my 436 with twin 88's didn't have a 1-1 ratio.Either way the cam in Fireball's engine in no way shape or form resembles an n/a cam
__________________ www.virginiaspeed.comcustom engines for street or race,tuning,installs,fabrication. check our our online store-i'm adding new products every day http://shop.virginiaspeed.com/main.sc757-468-5101 1979 Z28 Outlaw 10.5-670bbc twin promod 94's Crew Chief,engine builder,tuner of Phil Thomas's
LSX powered Mustang"The Renegade" 7.29, 198mph-best 1/8 et.4.70 @ 164mph 315 radials at 3275lbs
I've never seen an auto drag car with a 1-1 pressure ratio.they are way to lazy to spool.even my 436 with twin 88's didn't have a 1-1 ratio.Either way the cam in Fireball's engine in no way shape or form resembles an n/a cam
Since now one else asked, I will. Care to share the specs you are alluding too?
Since now one else asked, I will. Care to share the specs you are alluding too?
Apparently, they don't resemble traditional turbo OR NA cam specs, which leaves...um...nothing, since both of those run the entire gamut of split, reverse split, single pattern, long duration, short duration, high LSA, and low LSA.
__________________ 1995 Z28
388 LT4, AFR 210's, Home built T-76GTS turbo system
TH-350, Vigilante 10.5", Ford 9"
I've never seen an auto drag car with a 1-1 pressure ratio.they are way to lazy to spool.even my 436 with twin 88's didn't have a 1-1 ratio.Either way the cam in Fireball's engine in no way shape or form resembles an n/a cam
Well, my 388 on a little T76 GTS is at 2/1. Any smaller displacement or larger turbo can only improve on this, and you have both. Even if you were at 1.5/1, you're getting into the NA E-I pressure differential area.
__________________ 1995 Z28
388 LT4, AFR 210's, Home built T-76GTS turbo system
TH-350, Vigilante 10.5", Ford 9"
Well, my 388 on a little T76 GTS is at 2/1. Any smaller displacement or larger turbo can only improve on this, and you have both. Even if you were at 1.5/1, you're getting into the NA E-I pressure differential area.
yeah..but consider that I'm also running close to 30 psi and making probably close to twice the power (airflow) that your 388 is consuming...that air has to go thru the housing...is it bigger? yes...but that flow backs up in a hurry. I bet I'm approx 2:1 also...
__________________ 1999 Pewter T/A | Just another slow drag radial car (see here) Virginia Speed 366ci LS2 + big turbo (the little block that could) | 7.99 @ 177.8 (1.36)
Virginia Speed 388ci LS2 + bigger turbo | In Progress
Special Thanks to TheOutlaw1, Phil99vette, Shawn @ Va Speed and MADMAN for all their help
Well, my 388 on a little T76 GTS is at 2/1. Any smaller displacement or larger turbo can only improve on this, and you have both. Even if you were at 1.5/1, you're getting into the NA E-I pressure differential area.
you forgot to add in rpm and intake pressure in your equation.as both rise ex backpressure also rises.what rpm and intake pressure are you 2-1 at?Fireball is at 8000rpm and 30 psi,this makes a big difference
__________________ www.virginiaspeed.comcustom engines for street or race,tuning,installs,fabrication. check our our online store-i'm adding new products every day http://shop.virginiaspeed.com/main.sc757-468-5101 1979 Z28 Outlaw 10.5-670bbc twin promod 94's Crew Chief,engine builder,tuner of Phil Thomas's
LSX powered Mustang"The Renegade" 7.29, 198mph-best 1/8 et.4.70 @ 164mph 315 radials at 3275lbs
Just for giggles I called Comp Cams today to see what they recommend for my build. 370ci, 9.3:1, twin 61mm T3 turbos with 76mm turbine wheel .82AR, 15-20+lbs of boost, heavy as heck 4100lb GTO, TH400 trans, 3400 rpm stall, 3.46 gears. I want to hit 1000+ at the crank.
They recommended this:
228/230 .588/.592 on a 115 +3 with xer lobes.
Other folks are telling me this is a small baby cam.
Shawn at Va Speed is working on a cam for me right now. I just have to pay him, lol. Then of course sign my name in my own blood to not spill the beans on the cam specs. Just kidding, lol.
On my previous setup, this is what I had.....
370ci, 9.5:1, GT47-88 turbo, ported L92 heads, GMPP single plane, elbow and a FAST 78mm TB. I used a Comp 238-242 .605-.610 115 LSA on XER lobes. I shifted at 7000 rpm, it probably would have peaked a little higher, I just didn't feel the need to spin it more. It was a N/A type cam that worked great in a 88mm turbo application for me.
It made over 1000 hp, and took me well into the 8's. It spooled well, and ran pretty damn good. It was someting I shot in the dark with, since at the time, there was not any data of a 370 turbo and ported L92's. I consulted with several cam/engine guys, like Patrick G, Kurt Urban, Louis G, Ed Hutchins, they all told me to just try the cam I had and see how it performed. Nobody really knew how well it would do for sure.
That being said, on the new setup, I had Shawn spec me a custom cam for the new heads, and it does not look like my old one! The whole combination has to be taken into consideration.
__________________ 388ci C5R block, Virginia Speed Double O-Ring, ETP 265's, Solid Roller, Jesel, Callies, Oliver, BS3, TH400, MWC Race 9" and a big ass turbo! http://www.virginiaspeed.com www.midwestchassis.com
Just for giggles I called Comp Cams today to see what they recommend for my build. 370ci, 9.3:1, twin 61mm T3 turbos with 76mm turbine wheel .82AR, 15-20+lbs of boost, heavy as heck 4100lb GTO, TH400 trans, 3400 rpm stall, 3.46 gears. I want to hit 1000+ at the crank.
They recommended this:
228/230 .588/.592 on a 115 +3 with xer lobes.
Other folks are telling me this is a small baby cam.
Shawn at Va Speed is working on a cam for me right now. I just have to pay him, lol. Then of course sign my name in my own blood to not spill the beans on the cam specs. Just kidding, lol.
Edit: How would this work guys?
Magic Stick V.3 237/242 .603/.609 on a 114
What heads? I intend to use a 230/230 592/592 115 +3 once I get my forged guts and my AFR 225's in there. Should run high 8's.
__________________ 98Z28CobraKiller 370ci LQ9 + AFR225's + PT88 9.57 @ 142 so far
Last edited by 98Z28CobraKiller; 06-12-2009 at 10:00 AM..
What heads? I intend to use a 230/230 592/592 115 +3 once I get my forged guts and my AFR 225's in there. Should run high 8's.
its so easy, a caveman could do it
__________________ 1999 Pewter T/A | Just another slow drag radial car (see here) Virginia Speed 366ci LS2 + big turbo (the little block that could) | 7.99 @ 177.8 (1.36)
Virginia Speed 388ci LS2 + bigger turbo | In Progress
Special Thanks to TheOutlaw1, Phil99vette, Shawn @ Va Speed and MADMAN for all their help
__________________ 1999 Pewter T/A | Just another slow drag radial car (see here) Virginia Speed 366ci LS2 + big turbo (the little block that could) | 7.99 @ 177.8 (1.36)
Virginia Speed 388ci LS2 + bigger turbo | In Progress
Special Thanks to TheOutlaw1, Phil99vette, Shawn @ Va Speed and MADMAN for all their help
um...those are some rediculous durations to have 50* overlap at at 115 lsa
if the lobes were same I and E, it would be a 280/280 115
__________________ 1999 Pewter T/A | Just another slow drag radial car (see here) Virginia Speed 366ci LS2 + big turbo (the little block that could) | 7.99 @ 177.8 (1.36)
Virginia Speed 388ci LS2 + bigger turbo | In Progress
Special Thanks to TheOutlaw1, Phil99vette, Shawn @ Va Speed and MADMAN for all their help
| In Progress
