[Jack Gifford]

Nice work on the exhaust flow!

[steve25]

Thanks Jack.
It was no big rework, all of 15 to 20 minutes per port start to finish.
Most of that time was spent grinding the casting nub off of the apex of the short turn while not grinding in any divit’s .

The photo shows the nub.

I was very pleased that the other short turn work got rid of the flow stalling turbulence in the mid lift range that was taking place.

[steve25]

Well here’s my final installment on these SD455 heads since there getting assembled and bolted to the block this weekend.

Here’s the final intake flow numbers I am leaving off at so as to not overwhelm the intake manifold.

Also here is the what the exh short turn now looks like.

This is where most of the porting time went into on these heads in terms of the exh side.

You can find those exh flow numbers back in post # 60.
Note the main change in the short turn is the where the .448” arc starts and the removal of the big casting nub at the crown of the short turn.

Intake flow@ 28”
Second column is flow change over stock.

Note that terms of the intake side the valve job done and the slight back cut applied to the new valve was used to try and keep up with the flow of the stock Tulip valve.

The new valve also has a under cut stem.
.050”//// 32//// -.9

.100”////66.5//// -1.8

.150”//// 104.2//// -.5

.200”//// 136.6////. -2

.250”//// 173//// +1

.300”//// 194.8//// +12.5

.350”//// 215//// +5.6

.400”//// 228//// +10.6

.450”//// 234//// +7.5

.500”//// 240//// +4

.550”//// 248//// +8.8

.600”//// 254//// +10.3

.

[PAUL K]

Good job Steve!

[steve25]

Thanks Paul.
I figure that with the hydro roller the guys putting in the motor he could be looking at 480 Hp.
Since he’s running repro exh manifolds with there greater port are I hope my guess is close.