ws6transam.org AFR195 head testing

December 2002:

The Minirammed 385 project has received a large boost this month - Acquisiton of the cylinder heads! With a target compression ratio of 10.6:1, I needed a head with 68cc chambers to match the Lunati flat top pistons that are installed 0.005" down in the short block. Coupled with a 0.039 inch head gasket, the quench area will have 0.044" of piston to head clearance at top-dead-center. In addition, since this is an internally balanced forged and balanced stroker motor with a three-inch intake runner in the TPIS Miniram, I wanted to have some good flowing ports with decent volume. However, it is still a street motor, so I kept the intake runner volume below 200 cc. Hence, the decision to buy the AFR195 head. Now, on to business. The heads flow really well out of the box. AFR published flow data was within ten percent of the actual flow of these heads. However, I've noted a few details that I think will enable me to exceed advertised flow numbers. These details will be covered in a subsequent "fluff & buff" with ye olde die grinder. Once completed, I'll take them back to the engine shop and have them flow tested. The goal is to achieve at least a 75% exhaust to intake flow ratio. I also hope to see 280 cfm on the intake when finished. If I can achieve 280 cfm without greatly increasing intake volume, a net increase in intake port velocity should be the result.

The heads were ordered through Dave at Thunder Racing. There are a couple of other discount distributors that also offer a great price on these heads, with savings of about $50 to 100. Dave upsold me to a set of Titanium retainers because of my intended operation of 6000+RPM on a road race track. Expect a six week lead time from AFR for your heads. Contact me if you are actively shopping for these heads.

Flow Test data is here. The initial test of the cylinder head ports showed that AFR indeed advertises their stock flow potential. The advertised flow versus the measured flow were within ten percent. However, a hot rodder is never satisfied with out of the box performance. We compulsively tinker!

Hence, in an effort to improve air flow, I added a 30 degree back cut to the intake valve. Although this made a small (but measureable) improvement at low lifts, it probably if not enough to warrant the cost on this configuration of head and valve. The valves are stock AFR stainless pieces, manufactured in India by a company called "Karvalve".

Here is the exhaust port. It flows pretty good, but I noticed a few features that are artifacts of the CNC program. I assume that because AFR must strike a balance between perfection and economic machining, there is a compromise to the contour around the valve guide. It's quite flat and featureless. Therefore I am going to reshape the port around the guide to make a nice aerodynamic taper. Hopefully I'll pick up a few cfm.

Here's the intake port. Notice the three prominent ridges. These are also (I assume) artifacts of the CNC machine programming. It's a digitally controlled robot and some changes to the angle of attack are necessary to keep the tool fixturing from banging into the combustion chamber. These angle changes result in the big ridges you see. I'll be cleaning them up, along with refining the contour of the aero bump behind the valve guide. The result will be airflow test #3!

Here's the same intake port after cleanup. I've removed the three large ridges and slightly recontoured the radius around the valve guide. I have not drastically changed the shape of the bowl so I'm not expecting too much of a change. I might put some epoxy into the as-cast void behind the airfoil but I'm going to consult a few experts beforehand.

Here's the exhaust port. I've done a fair amount of recontouring of the long-side radius, ecpecially around the valve guide and directly behind it. It looked like the long-side radius was a little sharp around the guide so I blended it and created a little airfoil behind the guide.

Here's a before & after shot of the exhaust port as seen from the port outlet. Can you see the recontour around the guide and directly behind it? Once I flow test, I'll add the data into the table as airflow test # 3.

Last modified on Jan 4, 2003

	The heads were ordered through Dave at Thunder Racing. There are a couple of other discount distributors that also offer a great price on these heads, with savings of about $50 to 100. Dave upsold me to a set of Titanium retainers because of my intended operation of 6000+RPM on a road race track. Expect a six week lead time from AFR for your heads. Contact me if you are actively shopping for these heads.
Flow Test data is here.	The initial test of the cylinder head ports showed that AFR indeed advertises their stock flow potential. The advertised flow versus the measured flow were within ten percent. However, a hot rodder is never satisfied with out of the box performance. We compulsively tinker!
	Hence, in an effort to improve air flow, I added a 30 degree back cut to the intake valve. Although this made a small (but measureable) improvement at low lifts, it probably if not enough to warrant the cost on this configuration of head and valve. The valves are stock AFR stainless pieces, manufactured in India by a company called "Karvalve".
	Here is the exhaust port. It flows pretty good, but I noticed a few features that are artifacts of the CNC program. I assume that because AFR must strike a balance between perfection and economic machining, there is a compromise to the contour around the valve guide. It's quite flat and featureless. Therefore I am going to reshape the port around the guide to make a nice aerodynamic taper. Hopefully I'll pick up a few cfm.
	Here's the intake port. Notice the three prominent ridges. These are also (I assume) artifacts of the CNC machine programming. It's a digitally controlled robot and some changes to the angle of attack are necessary to keep the tool fixturing from banging into the combustion chamber. These angle changes result in the big ridges you see. I'll be cleaning them up, along with refining the contour of the aero bump behind the valve guide. The result will be airflow test #3!
	Here's the same intake port after cleanup. I've removed the three large ridges and slightly recontoured the radius around the valve guide. I have not drastically changed the shape of the bowl so I'm not expecting too much of a change. I might put some epoxy into the as-cast void behind the airfoil but I'm going to consult a few experts beforehand.
	Here's the exhaust port. I've done a fair amount of recontouring of the long-side radius, ecpecially around the valve guide and directly behind it. It looked like the long-side radius was a little sharp around the guide so I blended it and created a little airfoil behind the guide.
Here's a before & after shot of the exhaust port as seen from the port outlet. Can you see the recontour around the guide and directly behind it? Once I flow test, I'll add the data into the table as airflow test # 3.