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Wastegate actuator on top turbo looks like its gonna hit the strut tower when the engine moves on the mounts. I had that issue with my big single, needed like an inch of clearance to prevent it.
Wastegate actuator on top turbo looks like its gonna hit the strut tower when the engine moves on the mounts. I had that issue with my big single, needed like an inch of clearance to prevent it.
260hp/turbo is likely the rated piston-engine number. General rule of thumb for rotary engine power when it comes to rated numbers is divide by 1.3
I'm sure it'll spool like hell, but likely won't make more than 400whp. Really nice looking setup though.
Also, another thing to consider is that those are divided turbine housing's. You have 2 exhaust ports and 2 turbos. There shouldn't be a need for divided turbine housings.
Also, another thing to consider is that those are divided turbine housing's. You have 2 exhaust ports and 2 turbos. There shouldn't be a need for divided turbine housings.
I was just going to say the same thing. That might even hurt the flow. Twin turbo 2 rotor manifold sounds like a nice quick and easy way for fabricating a turbo manifold! Or should I say turbo pipe.
Looks good. I've thought about using v-band inlet turbos for a twin setup, it makes everything much more compact and movable compared to having two T3 or T4 flanges. Looking forward to seeing your dyno results!
but bumping this for similar recent topic; 13B with twin Garrett G25-660 turbos (one per rotor) swapped into an awd Subaru with Xtrac sequential trans, think it’s still not fully built out yet, but shooting for 700 whp
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youtube vid on the dyno shifting through the gears
that is kind of a serious build, KSP was doing 731hp back in the day with a pair of HKS GT3037's and a bridgeport 13BT
i wish i would have saved more pics
was kind of wondering if two G25-550 IWG 0.49 AR V-band could fit in an REW-RX8
the dual turbos were a thing in Japan in the 90's when there was a trend toward big power and there were not a ton of turbo options, obviously the plumbing is a pain and the cost is double the correct single.
I get that line of thought, but not 2x more imo if looking at equivalent technology. Even some single turbo builds can be 2x cost difference between each other in that regard.
if I were to attempt it then I’d take a cheaper route of using the Pulsar G25-550 copy cat turbos though, which they offer in the 0.49 IWG V-band that Garrett doesn’t have and at only $900 each. Two of those are about the same cost as one Garrett. The RX8 chassis with REW swap has some more space down low than the RX7 and with IWG the exhaust manifolds won’t be overly complicated if they can fit as I’m envisioning it. The support piping is double, though some can be manifolded rather than separate, but the inlet, exhaust, and compressor discharge piping is for sure some more work and cost.
Where I see the possible advantage is in the response relative to the peak power output. It seems that two of these small turbos fairly close-coupled to the exhaust ports may offer some potential to come on sooner than an equivalently sized single. Which as proposed would be a Garrett G35-1050. In the RX8 chassis that would require a forward/high mount manifold with less balanced, longer path exhaust flow, EWG, etc..
Honestly, if there was a smaller G20-500 option with 80% eff. I’d probably be all over it. Garrett did recently release some smaller GBC turbo options, but too small for this idea and less efficient than the newer G-series because they’re based off the previous Gen2 technology; only 72% peak eff and 58% eff at the far right, meh. Mostly blowing smoke out my tail pipe though, on topic for this subject
as these get smaller with more punch, possibly has potential
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but here’s the difference in chassis space, this is an RX8 chassis with custom-fit manifold and EFR9174 0.92AR (picture credit to Jesse/RotaryMachineRx):
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given this a G35-1050 could likely be mounted the same
However, when you look at the combined turbine flow of two 0.49AR G25 turbos, it starts 19 lb/min @ 1.3 PR, which is well below where the G35 0.83 and 1.01 AR turbine flow curves start, and from there it jumps up to just above the 0.83 AR flow curve until 2.0 Pr, where it then moves up to the 1.01 AR flow curve until 3.0 PR (32 lb/min) and then flat lines. So on paper it looks peppier than a G35 0.83 low-mid, but then extends out to the G35 1.01 on the top end. Except those housings only come in an open V-band inlet configuration and this is like a divided configuration. The divided T4 housing is only in a 1.06 AR. Looks tasty
So even just looking at these pics it sure seems to me like they could be squeezed down in there very close-coupled almost direct to the exhaust ports.
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If you ran an electric oil scavenge could you fit a g35 right at the base of the firewall? I need to pull my finger out and get a hoist so I can play with fitment on my 7.
Frankly I think it just depends on your goal. First I don’t think an electric scavenge is necessary, at least not on an RX8 chassis. I’d have to rely more on other people’s experience on the FD chassis. Otherwise I believe it’d depend on your goal. Top end power I’d concede to the G35 single setup. Low end response, I’m inclined to swing to twin G25 turbos as proposed.
All of which is based on the data we have. The actual results remain to be seen. Technically the G25-660 and G30-660 are the same dimensions though. So there potentially is a higher power option, but then you’re into the G40 range with a full array of divided T4 options.
07-01-14, 03:44 PM
