2.3 Head Flow Comparison Chart

[Stinger]

Head Flow Data from BoPort Racing Heads:

All heads were bone stock other than cleaning carbon off the ports. Factory valve job, same valve used for all tests. This is an intake flow comparison tested at 28" water on the flow bench. A 1/2" clay radius was used on the port entrance. Cylinder number 3 port was used on all tests but the ranger round port, in which cylinder #4 was used. Back to back testing was done on the same day.

Lift	N/A D Port	Turbo D Port	N/A Oval Port	N/A Round Port	Late Dual Plug	Early Dual Plug	Esslinger D Port	Ported Esslinger D Port	Ported Turbo D Stage 4	Esslinger ARCA	Volvo	Esslinger XT	Chinese Iron
.050"	27.55	27.8	28.6	31.0	30.0	27.3	28.1	29.6	33.2	33.7	42.3
.100"	48.9	54.5	55.9	59.0	58.0	54.9	51.4	61.3	65.6	61.3	85.1
.150"	61.8	75.4	78.9	77.7	86.7	78.3	76.7	94.5	106.5	91.6	123.9
.200"	75.2	100.6	100.3	101.6	110.7	96.1	105.5	123.6	138.8	122.0	164.1
.250"	88.0	120.7	122.3	122.0	130.3	109.4	132.3	147.2	169.3	149.8	198.5
.300"	101.6	132.3	136.8	135.5	143.3	120.4	156.3	169.9	196.5	175.8	219.2
.350"	116.5	140.1	146.6	142.7	153.1	128.4	177.7	189.4	218.6	198.5	226.4
.400"	131.0	144.0	150.5	145.3	158.9	132.3	190.7	207.6	234.8	218.6	229.6
.450"	144.0	149.2	153.1	145.9	164.1	134.9	199.8	220.5	247.1	236.1	231.6
.500"	151.8	154.4	156.9	149.2	166.8	136.8	205.6	231.6	250.4	252.3	234.1
.550"	158.2	159.5	156.3	150.5	168.8	138.8	210.1	236.1		265.9	235.4
.600"	163.4	160.8	156.3	151.8	170.2	140.1	214.7	237.4		275.0	235.4
.650"							206.9			283.1
.700"							207.6			290.2

[Strangeleak]

Awesome data!

How much room does a Volvo head have to port? Can it take larger valves? That would be interesting to see.

[Stinger]

It can be improved with porting, and can have slightly larger valves installed. Getting performance cams for it is an issue though.

[mavereq]

I've been reading up on the ranger round port. I read that they're capable of great flow but they're hard to port without hitting water. I have one and have been toying with the idea of porting it myself. Do you have any experience with them?

[Stinger]

I don't have any porting experience with them.

[mavereq]

Curious about the low numbers on the n/a d-port. Are the runners a lot smaller, or does the combustion chamber shroud the valves too much?

[Stinger]

I don't know for sure but that's the likely cause.

[don33rbc]

Wish he would have flowed an Esslinger SVO head.