port flow (c1j ported big valves) [Archive]

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patrick

01-05-2011, 20:39

New poster! (less than 10 posts)

hi guys,has anyone ever flow tested a gtt head here, and has got some numbers??i flow tested mine and just want to know if i`m way behind or at least nearing a good ported head.
any help appreciated tnx.

Matt Cole

01-05-2011, 22:16

patrick

02-05-2011, 09:11

New poster! (less than 10 posts)

thanks matt,that was helpful!! now i`ve got a graph,ijust need to ask him if it`s a std port or a ported one that he tested and hope he`ll reply.tnx again.:)

http://www.rtoc.org/boards/showthread.php?t=18250&highlight=flow+bench

Andrew Cooke

02-05-2011, 15:56

I'm not sure that you can really compare your modified results with my standard ones. I'm happy with the repeatability I get between tests, but wouldn't like to say how well my bench compares with a different bench. You'd be best to compare your head to a standard head on your own bench.

Andy

http://www.rtoc.org/boards/showthread.php?t=17946
btw, Henry is currently working as a builder, cleaning up dust and rubble...

patrick

02-05-2011, 19:02

New poster! (less than 10 posts)

i get your point and know what your saying nevertheless if you are rigged up and aligned properly to a std 76mm bore and pulling 10 inches water i don`t think that it will vary that much,besides you already compared your flow test with the flow test`s results obtained on another flow bench and they were pretty close! so that port you tested is a std unmodified port??

I'm not sure that you can really compare your modified results with my standard ones. I'm happy with the repeatability I get between tests, but wouldn't like to say how well my bench compares with a different bench. You'd be best to compare your head to a standard head on your own bench.

Andy

http://www.rtoc.org/boards/showthread.php?t=17946
btw, Henry is currently working as a builder, cleaning up dust and rubble...

Andrew Cooke

02-05-2011, 19:17

I don't pull 10", I compensate for the pressure drop I can get. I've not tried any genuine calibration plates, so I really can't say how accurate it is. I suspect it's pretty good, but then I also thought my first attempt at porting was good, the bench disagreed.

I'm not too worried about absolute accuracy as long as I can get repeatable results, I seem to get those, so I'm happy.

My flow curve was for a standard head, what results have you got? Post them up.

I'm using a bare head with a plasticine 'trumpet'. I don't think I did any tests with the inlet manifold fitted, or port to port comparisons as I was just interested to see how it compared to the Gordini head rather than looking to develop the GTT one.

Andrew Cooke

02-05-2011, 19:19

Oh, it's a 76.6mm bore on my rig to match my engine, but I don't think that'll matter on the GTT as the valve is pretty deep in the head.

patrick

02-05-2011, 19:46

yeah it is pretty deep :agree: but you never know... anyway my head`s flow results are almost identical to the ones you`ve got for the gtt so if your gtt`s port was std may be the flow benche`s results are way off from one another or my porting is crap!! :)

Oh, it's a 76.6mm bore on my rig to match my engine, but I don't think that'll matter on the GTT as the valve is pretty deep in the head.

Andrew Cooke

02-05-2011, 19:54

without being rude it's possible that your porting's crap, been there, got the t shirt:rolleyes: It's a pity that you're not in the UK so that we could test each other's heads.

I did a comparison between my standard Gordini head, and a pro big valve big port version, and there was no difference until the lift got quite high. It's possible that the loss in gas speed from the bigger ports would negate the gain in flow at high lift.

Post what you have, there may be something in the 'shape'.

patrick

02-05-2011, 20:29

i`m uploading the results i hope they uploaded o.k....

without being rude it's possible that your porting's crap, been there, got the t shirt:rolleyes: It's a pity that you're not in the UK so that we could test each other's heads.

I did a comparison between my standard Gordini head, and a pro big valve big port version, and there was no difference until the lift got quite high. It's possible that the loss in gas speed from the bigger ports would negate the gain in flow at high lift.

Post what you have, there may be something in the 'shape'.

Andrew Cooke

02-05-2011, 20:32

OK, I'm off out for the evening now. I'll try to remember to post my numbers as the graph isn't as clear.

patrick

02-05-2011, 20:33

thanks again mate...

OK, I'm off out for the evening now. I'll try to remember to post my numbers as the graph isn't as clear.