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When I datalogged my 60mm WG with and without divider up to WG poppet face it was from idle to 2,500rpm the purely divided wastegate really helped boost. Like double from 2psi to 4psi @2,000rpm, but no different above 2,500rpm.
It wasnt like decreasing intake restriction with velocity stack and 12" filter which helped boost build in low rpm and carried the spool curve all the way up to WG opening.
WG runner theory is interesting.
If you look at the early Trust/Greddy designs they tried to keep the two WG runners to a single WG the same length as turbo runners post WG plus Turbo exhaust housing. That way the exhaust pulses at the WG collector interacted at the same time as turbo exhaust wheel pulses.
Later they gave up on that and just put a single WG runner at the turbo flange.
I assume they found a turbo manifold that isnt cracked spools better than a cracked one with careful pulse tuning engineered in.
Likewise, I couldnt make a WG divider survive racing and gave up.
Good info - I agree with the inevitable cracking of the old Greddys and other dividers. I haven't tried to make one last but I've seen a bunch of attempts that tend to end in sadness.
i have run a single 60 mm Tial wastegate since 2013... it is divided. you can see the partition on the valve head.
No doubt - fully divided with a protrusion to the poppet face is superior and after seeing a photo of your latest cast manifold I'm sure it's fantastic. I think (and correct me if I'm wrong) that @BLUE TII and I are saying that older cast as well as fabricated units would consistently fail to the point where I'm a bit leery VS gains to be had on that last 1/4" or what have you - I'm sure modern (with regards to adoption rate, not that they haven't existed) cast materials such as stainless will be an evolution in longevity.
I’m the one with the rx8 rew conversion with a artec and psr 6262g
i didn’t dynoed it but I can say this combo spools faster and hits harder than my previous hks cast with gtw3884r ever did. Sure the old
turbo had a 1.05 vs the new is 0.85 but before, the car would be lazy and slow to come alive, now it’s much more reactive. So far this setup works great and can’t complain. I see boost around 3000rpm and I’m full boost around 3500-4000 depending on gear. I’m in the process of tuning my boost controler pid so its not perfect at the moment.
Quick fact, the g series chra is much shorter and is a lot harder to work on.
I also went external dump on the wastegate at the same time to decrease exhaust gas flow in the exhaust. I had a 5 psi spring before in my wastegate but it was screaming each time I let off the accelerator so I put a 13psi spring in it to keep it shut when I’m cruising. I had to reuse my adapter/extension on the wastegate to move it further back otherwise it would have been in the downpipe’s way. I know it’s not optimal as it’s not divided but it works. I know someone fitted a turbosmart gate directly on the manyfold but he had to dent the underside of the car to make it fit, the tial head is much bigger and wouldn’t fit, plus it would be right next to the downpipe with all the heat. The guy also has a 8374 on the artec in a rx8 (https://www.instagram.com/stuermer_1...d5MDRweHRlbw==)
Last edited by Mad666max; May 11, 2025 at 08:49 PM.
I tried the whole electric wastegate thing. It just doesn’t respond fast enough. Maybe the straight gate will be better, but you’ll need 2 and that’s super pricey. If you’re just using one, well, then you have all the drawbacks of single wastegate design.
It was OK on power, but the boost curve was never right it just couldn’t react fast enough. If you pulled throttle and then went back on the car didn’t like it at all.
I have 2 40mm conventional straight gates sitting here, going to see if we can get them to fit on a shorty style manifold. I love the idea of running 5x spring pressure so I can just open everything when I’m not in the mood to push the car. I don’t have high hopes, they are much bigger than I expected and there’s not much room at all especially RHD.
But yeah. E gate, not fast enough. It was an OEM Honda gate IWG kit, but twin e gates is above my comfort level after that failure. And it wasn’t a quick fail, we spent 4 hours on the dyno getting the gate boost map sorted, and I drove the car for a month with the gate on. It wasn’t ever as good as a normal TS IWG gate.
I’m manifold shopping, sort of. Shop here makes a really beefy single gate EFR manifold that is used for all the competition circuit cars here and survives. Pretty much everything else cracks after 30 minutes at full tilt. So that’s likely the direction I’ll go. But the V2 turblown is looking really tempting.
