Oversized valves - SR20 intakes / exhaust
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Re: Oversized valves - SR20 intakes / exhaust
The quality of your work is exceptional. Ive seen heads with a fortune invested in professional experienced porting not look as uniform and well thoughtout as this. I can't wait to see what you do with this engine.
na6 progress thread - http://mx5cartalk.com/forum/viewtopic.php?f=57&t=68039
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Re: Oversized valves - SR20 intakes / exhaust
Cheers... I was actually suprised how easy it was. Its definitely something anyone with an air compressor and a die grinder can do. You just need a bit of patience and be methodical. I stepped through each port in turn doing the same process whilst counting in my head to get a similar amount of time. The key is to do small amounts of work each time so you can remember what you did and replicate.
It will be interesting to bench it against a stock and my race head to see how I did. I might make a flow bench to test heads.
It will be interesting to bench it against a stock and my race head to see how I did. I might make a flow bench to test heads.
NA8: N/A 200whp | Haltech | Skunk2 Intake | S90 TB | RCP | 5 speed c/r dogbox | 4.78 diff | AST Shocks
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
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Re: Oversized valves - SR20 intakes / exhaust
I'm gobsmacked, those ports look like a work of art.
Satans Ride called F33nix the resurrected NA6
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Re: Oversized valves - SR20 intakes / exhaust
madjak wrote:.. I might make a flow bench to test heads.
I have a ported and polished early NB head that would be interesting to compare them to.
If you had access to a car like this, would you take it back right away? Neither would I.
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Re: Oversized valves - SR20 intakes / exhaust
Do you have it off the car? It would be interesting to test.
NA8: N/A 200whp | Haltech | Skunk2 Intake | S90 TB | RCP | 5 speed c/r dogbox | 4.78 diff | AST Shocks
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
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Re: Oversized valves - SR20 intakes / exhaust
Yup
If you had access to a car like this, would you take it back right away? Neither would I.
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Re: Oversized valves - SR20 intakes / exhaust
Wow... back to here again!
ok, so for the community knowledge base AKA google search, here is an update:
Nissan SR20DE valves fit, These are +1.15mm oversized on Intake, +1.15mm oversized on exhaust (6mm stems but are a bit short so you may need to run 2 x stem cap shims to fill the space)
Nissan SR20DET valves - Intakes fit (same as above), exhaust don't (they have a 7mm stem)
Nissan RB26 Intake valves fit, These are +1.5mm oversized and a perfect length to fit in. Exhaust valves are probably too large but would fit if you had to. Probably best to get Supertech +1 exhaust valves.
All Nissan valves run the same tolerance for valve guide as Mazda so they slide right in (Intakes around 5.97ish, Exhausts around 5.6ish) which means you need a 6mm reamer for the correct tolerances.
If you run Nissan valves, you need the Nissan cotters which fit into later model Mazda retainers or Supertech retainers. You can machine the stock Nissan valves to open up the D indent on the stem to fit the Mazda cotters if you prefer. It easy enough on the SS valves, but I couldn't even scratch the Supertech valves as they are nitrited. Probably need a diamond grinder.
I'm currently building my race head with Supertech RB26 intakes, and Supertech Mazda +1 o/s exhaust. Nissan cotters on the intakes, Mazda OEM cutters on the exhausts. I have done a 4-angle cut on the seats with Neway cutters, and installed bronze valve guides. I'll post some pics of it all together tonight.

ok, so for the community knowledge base AKA google search, here is an update:
Nissan SR20DE valves fit, These are +1.15mm oversized on Intake, +1.15mm oversized on exhaust (6mm stems but are a bit short so you may need to run 2 x stem cap shims to fill the space)
Nissan SR20DET valves - Intakes fit (same as above), exhaust don't (they have a 7mm stem)
Nissan RB26 Intake valves fit, These are +1.5mm oversized and a perfect length to fit in. Exhaust valves are probably too large but would fit if you had to. Probably best to get Supertech +1 exhaust valves.
All Nissan valves run the same tolerance for valve guide as Mazda so they slide right in (Intakes around 5.97ish, Exhausts around 5.6ish) which means you need a 6mm reamer for the correct tolerances.
If you run Nissan valves, you need the Nissan cotters which fit into later model Mazda retainers or Supertech retainers. You can machine the stock Nissan valves to open up the D indent on the stem to fit the Mazda cotters if you prefer. It easy enough on the SS valves, but I couldn't even scratch the Supertech valves as they are nitrited. Probably need a diamond grinder.
I'm currently building my race head with Supertech RB26 intakes, and Supertech Mazda +1 o/s exhaust. Nissan cotters on the intakes, Mazda OEM cutters on the exhausts. I have done a 4-angle cut on the seats with Neway cutters, and installed bronze valve guides. I'll post some pics of it all together tonight.

NA8: N/A 200whp | Haltech | Skunk2 Intake | S90 TB | RCP | 5 speed c/r dogbox | 4.78 diff | AST Shocks
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
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Re: Oversized valves - SR20 intakes / exhaust
Madjak, where did you purchase your Neway seat cutter from? I have found various US and UK suppliers, but no-one local to our continent.
And would you share which size/part numbers you have? I have been considering doing my own seat work for my next B6 head, when and if I get a Round Tuit.
And would you share which size/part numbers you have? I have been considering doing my own seat work for my next B6 head, when and if I get a Round Tuit.
WP:1.12.492 SMPN:1.16.403 SMPS:1.05.473 SMPGP:1.53.256 SMPB:2.22.181
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Re: Oversized valves - SR20 intakes / exhaust
Redlands Reconditioning Supplies in QLD.
The guys there are super helpful and even measured the max and min sizes for me for a cutter. The ones I got I doubt will fit the B6 exhaust ports as the cutters scrap in the side of the combustion chamber of a BP.
There are two drive sizes so you might have to drop to the smaller size.
The guys there are super helpful and even measured the max and min sizes for me for a cutter. The ones I got I doubt will fit the B6 exhaust ports as the cutters scrap in the side of the combustion chamber of a BP.
There are two drive sizes so you might have to drop to the smaller size.
NA8: N/A 200whp | Haltech | Skunk2 Intake | S90 TB | RCP | 5 speed c/r dogbox | 4.78 diff | AST Shocks
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
Barbs L: 64.12 | S: 58.62 | Collie: 49.72
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