PipeMax/ porting for turbo app. - Exhaust choke questions...

[99R/T]

I just bought PipeMax, great program, TONS of data to decipher.

I was wondering about the exhaust port choke numbers, with a turbo app, you'd have more volume than in a N/A application, but also more back pressure.

How should I size my exhaust port/throat, are there any formulas I can use to take these into account?

The engine is a 5.9L Magnum in a MPI Dakota, factory heads with 2.00 intake and 1.65-1.7" exhaust. 8.7-9.0 compression, 8-10# of boost on pump gas, 10-12# with alcohol injection, and 12-14# on C16.

Edit: cam will most likely be a 220*I/210*E@.050, .544/.544, 106*CL/112*SEP off the shelf, though I'm waiting until I finish the heads to finalize it.

[200cfm]

I believe version 4.0 is suspose to address boosted engines. I run boost myself and waiting for that version to be released. How did you select that cam profile for boost?

[thomasvaught-1]

220*I/210*E@.050, .544/.544, 106*CL/112*SEP

Not a bad little camshaft:

10 degrees more intake vs exhaust.
Nice lift
Cam ground on 109 LC with 3 degrees advance.

Compression ration will easily allow more boost with good head gasket sealing @ 8.7-9.0 to 1.

Tom V.

Ford Motor Company (Boosted Engine Senior Engineer) I post on the Turbo Mustang board as Boost Engineer.

[200cfm]

Tom V, give me your opinion please on this cam spec.
12/58/58/12 250/250 @ .050". 112 lsa, 24 overlap, straight up install. .690 lift before lash.


And this one: 14/58/54/10 252/244 @.050 112 lsa, .540 lift
Has 8 degree retard grind on the above if installed straight up.

[200cfm]

Correction on the post: the 12/58/58/12 has 113 LSA, ICL @ 113 and ECL @ 113. Concerned about the duration and overlap for turbo boosting response.

[thomasvaught-1]

200 cfm, the first camshaft will make some serious power. For the duration the overlap is about right. Lift is really good. I like 114-116 lobe separations but many have made good power on 113 stuff. I would advance the camshaft 5 degrees so 108/118 for the lobe timing.

I DO NOT like camshafts with retarded timing.

Tom V.

[200cfm]

Thanks, the first cam is from LSM. Still in the box here and hoping to test it out later this year if I can resolve the spring pressures, install height and other roller issues. No guidance provided on lash or spring requirements. The second cam is one I got from a salts flat Avanti racer. I hope they work. The first one uses the PipeMax maximum effort recommended lift.

[99R/T]

That's odd, I wasn't notified of a reply

Thanks Tom,

As far as head sealing goes, I'm kinda weary. I'm used to running SBCs, this is my first Mopar engine. I don't like the idea of only having 4 head bolts. I'll be studding it, and I'm still stuck between running a Cometic MLS or just throwing a FelPro fiber on it as I'm not going to pull the engine and tear it down just to deck it. Would running a granite surface plate with emery paper across the deck give me a smooth/straight enough finish for an MLS?

And back to the original question, should I stick with the 1.650" exhaust valve with an 85%-88% throat, or should I hog it out to 1.700"?