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Slysc
02-03-2006, 03:53 PM
I'm in the process of making an intake manifold and I have obtained a formula to calculate optimized runner length for a certain RPM.

One of the variables that I need for the formula is the intake valve closure angle at .15mm. I think that is the degree at which the intake valve is at .005" before it closes.
I've got the .520 lift Dr. Fred "wicked" cam. I never got any cam specs. with it. Does anyone know what that IVC might be for my cam?

CMac89
02-03-2006, 04:15 PM
Dan, I have a very accurate engine analyzer program that I use for racing also and it has all of those features. If there's something that I can do then holla.:)

Toms-SC
02-03-2006, 05:14 PM
Call Crane cams? I think thats who he got to do his regrind.

Slysc
02-03-2006, 05:18 PM
Sure, if you could figure some estimates for me, that would be great.

If I want to optimize for a certain rpm, am I going to want that to be like 4000 rpm where I want loads of torque or should that be 6500 where I want peak horsepower?

I'm thinking my intake air temp is going to be around 70 with a boost cooler and since I don't know my cam spec. yet, anywhere from 106-111 degrees IVT should be in the range.

Could you give me a runner length based on that info?

Slysc
02-03-2006, 05:19 PM
the regrind was done by comp cams.

CMac89
02-03-2006, 06:28 PM
Dan,

It requires the whole engines statistics since they are more than relevant to the intake runners length. Rod length, stroke, bore, cam specs, head flow, and cfm from the blower. Can't think of anything else needed.

XR7 Dave
02-03-2006, 06:47 PM
the regrind was done by comp cams. You'd have to pull the cam and get the grind #'s off the back of it. Fred used a couple different durations on his ".520" cams.

supercatxr7
02-03-2006, 07:53 PM
Came across an old email from when I sold my Dr. Fred cam and asked him about the specs:

Fred Holzhauer wrote:
> > > > > .520 lift
> > > > > 212 intake
> > > > > 218 exhaust


That's all I know, no cam card with mine either.

mark

Burbank95sc
02-03-2006, 08:49 PM
I've got this cam from one of the members here,I can't remember who.I don't know ,if this is Dr.Fred cam but it has .520 lift.So , here is the cam card.
http://img346.imageshack.us/img346/8970/520camspecs3fo.th.jpg (http://img346.imageshack.us/my.php?image=520camspecs3fo.jpg)

Dirk SC
02-03-2006, 09:03 PM
Comp Cams

PART # 99-999-3
GRIND # misc 3342/3343 HR112+3
SPC INSTR 1:
SPC INSTR 2:
INTAKE EXHAUST
VALVE ADJUSTMENT HYD HYD
GROSS VALVE LIFT .520 .520
DURATION AT
.006 TAPPET LIFT 264 270
VALVE TIMING OPEN CLOSE
AT .050 INT: 3- BTDC 35 ABDC
EXH: 44 BBDC 6- ATDC
THESE SPECS ARE FOR CAM INSTALLED
AT 109 INTAKE CENTER LINE
INTAKE EXHAUST
DURATION AT .050 212 218
LOBE LIFT .3010 .3010
LOBE SEPERATION 112.0

RECOMMENDED CC VALVE SPRING
VALVE SPRING SPECS FURNISHED
WITH SPRINGS

Slysc
02-06-2006, 05:05 PM
Thanks for the cam specs. :)


Dan,

It requires the whole engines statistics since they are more than relevant to the intake runners length. Rod length, stroke, bore, cam specs, head flow, and cfm from the blower. Can't think of anything else needed.

My rods are 6.2" long, 3.4" stroke, 3.831" bore, use the cam specs above, heads flow 220 intake and 210 exhaust @ .600, and the turbo flows up to 900 cfm.

The formula I was given is:

Runner Length = ThetaT x 49 x square root of intake air temp
+ 460 x .3048/.012 x RPM

ThetaT = 85+(IVC-230)/2

Temp in degrees F
RPM is the desired tuning speed
IVC is the Intake Valve Closure angle at 0.15mm

David Neibert
02-06-2006, 05:15 PM
and the turbo flows up to 900 cfm.

Dan,

The Turbo ??? Does this mean your coming over to the darkside ?

David

Slysc
02-06-2006, 05:20 PM
The intake I'm building would be for a turbo. If I finish this turbo setup, it probably won't be anytime before this fall.

I'll start the season with the M90.

CMac89
02-06-2006, 05:31 PM
I completely forgot about this. Sorry about that.

I'll try to get the numbers for you tonight.:)

David Neibert
02-06-2006, 05:33 PM
The intake I'm building would be for a turbo. If I finish this turbo setup, it probably won't be anytime before this fall.

I'll start the season with the M90.

Dan,

Cool....have you already considered using a 3.8 NA manifold ? Even using the lower potion and building a bread box upper would be a big improvement over the SC manifold.

Even if you used the stock 3.8 NA upper, with a turbo I bet it will flow enough to make huge power (500+rwhp).

David

Slysc
02-07-2006, 05:37 PM
The manifold that I'm building is made out of a NA mustang manifold lower with a plenum on the top. I'm getting about 9" runner length out of that. My calculations so far say that for a 4000-7000 rpm motor, I should be have runners around 20" long. I may check out the 4.2 truck cross ram manifold.

I have some pictures of my manifold but they are too big to attach.

David Neibert
02-07-2006, 06:33 PM
Dan,

With a turbo...alot of that runner length theory goes out the window. Just make sure to have a large enough plenum. However...many of the turbocharged 03/04 Cobras are finding more performance by installing the 01 Cobra intake manifold and using an air to air IC. Mainly the longer runners provide better torque before the turbo spools up and will help to spool it up quicker.

Everything I've read about turbocharging says...the more flow going in the better (I'm using oversized heads and an 8000 rpm intake). Also the bigger the exhaust after the turbo the better. Mine would probably run better with a GT40 style long runner intake from idle until the turbo spools, but after the boost comes on, it doesn't really matter..the bigger the better.

If I were you I'd try the manifold you already have, I think you will be very suprised at how much power you can make with it.

David

CMac89
02-07-2006, 07:11 PM
What David saying is true. It will change the power minisculely in either direction you go. The longer runner you get then the more velocity there is, therefore, a tq increase is gained. From what I have seen in previous analyzing tests all applications relate directly in runner length. The length isn't as important as the volume of the intake manifold/runner.

The higher volume you have then the less the turbo has to work to make the same power.