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The threads I remember reading were GT3582R (so like EFR 8374 size) turbos around 400rwhp losing 25-30hp, but I didn't find those with a quick search.
I found this one which lost 17rwhp on back to back dyno around 15psi boost (pic of chart no longer showing up, so IDK power). https://www.rx7club.com/single-turbo...-proof-657974/ I found this one that still has the pic of the chart working that lost 20rwhp from 345rwhp with open vented WG. Also back to back on same dyno and same day. https://www.rx7club.com/single-turbo...uffler-994766/ |
A loss
Well i dont mind the noise my car makes with the dual wastegates. It is not a daily driver. The loss of power and trying to regain that power by adding more boost for me is a no go. I like a reliable rx7 not a high hp unreliable car. I make my car faster by reducing weight,cooler intake temps, tuning and improving the ignition system. I guess i will just need a better tune for that fuel smell. Just dont want to lean the engine trying to do it. I guess there is always race fuel. Oh that cherry smell from that fuel i can do that for sure.
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Originally Posted by SirLaughsALot
(Post 12237401)
I would suspect this being a bigger issue if it's routed earlier than a foot or so after the turbine exit. Should make less of a difference if you put it 2ft away, 3ft, etc, and making sure it meets inline with the charge.
https://cimg3.ibsrv.net/gimg/www.rx7...b28ebf7101.jpg I don't really care what it cost me for power lol, few things sound as raunchy as a open dump 13B. I also built a small wastegate muffler but couldn't fit it. Ended up using it on my brother's car, it seems to be a nice balance between the two extremes. |
Idea
A muffler vs a dump hmm. I wounder it this would cause a loss of power.
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Doubt it. With the muffler on, his setup will hold spring pressure within 0.25 psi without any PID or DC corrections.
Not a 13B and you have to turn the volume way up but you can get a bit of an idea. On the dyno, there is no audible change in sound when the gate opens. Open dump: Recirc: https://www.youtube.com/watch?v=6sXtm1gLpic |
Originally Posted by BLUE TII
(Post 12237340)
Over the years there have been several threads by owners that have dynoed their RX-7s before and after re-routing the wastegate back into the downpipe and 25-30rwhp is the normal loss in power on a ~400rwhp rotary.
I imagine there is at least that much loss in power between IWG and EWG EFR turbos as well. Possibly more since it is 0.92AR IWG versus 1.05 or 1.45AR EWG exhaust housings with the EFRs.
Originally Posted by IRPerformance
(Post 12237346)
25-30hp loss when rerouting the wastegate at the 500hp level seems to be the norm all other factors remaining consistent. The biggest reason for this is the turbulence introduced into the system and it can vary significantly depending on how the wastegate is rerouted. If the system is designed from the start to be recirculated, then the loss may not be as prominent. EFR turbos do tend to take a pound or so more to make the same power as a similar SXE counterpart so some of this still applies. Some ways to get around it is to introduce the wastegate discharge at a smooth transition or go slightly larger on the exhaust. All this being said, the different for the majority of applications is negligible and many prefer a quiet car over a few hp.
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That is a good point.
The results showing a power loss from re-routing the wastegate into the downpipe would have all been on 3" exhausts. All turbo exhaust were basically 3" diameter in the US until this decade when the advantages of larger exhaust (especially downpipes) became more common knowledge. 3" exhaust on a turbo car was just one of those "rule of thumbs" that keep us mediocre. |
2019
2019 is here and I am tired of my setup and almost financially ready for the switch to 8374 iwg turbo. Before I switch I have been researching the boost spike situation with this setup. I see some persons porting the iwg. I have also seen a video of a guy changing the iwg all together with a iwg with two ports. Who has tried any of these things with good or bad results?
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If you have a cat in there, there shouldn't be a problem mine was prefect at 14 psi all 3in. One i put a mid-pipe on i couldn't control the boost at all. So depends on your exhaust setup.
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Originally Posted by spintriangles
(Post 12342655)
2019 is here and I am tired of my setup and almost financially ready for the switch to 8374 iwg turbo. Before I switch I have been researching the boost spike situation with this setup. I see some persons porting the iwg. I have also seen a video of a guy changing the iwg all together with a iwg with two ports. Who has tried any of these things with good or bad results?
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A lot of what people would consider boost creep issues appear to be user setup problems. I recently saw a customer have this issue, and low and behold, switched his ignition and ecu system and problem went away( power also jumped up 17%). Porting the turbine housing definitely works for very high flowing setups, recently had a customer hold 14.5psi( base spring pressure in the turbosmart actuator upgrade) with a full 4" exhaust on his cast 8374 IWG system. A full 4" exhaust will creep on 90% of EWG turbo manifolds FYI, regardless of turbo brand.
I have already tuned long, short, big and small tube IWG kits and confirmed it makes no difference on the boost control. To be clear here I have seen a long runner, equal length manifold creep on the dyno. This one was also fixed by just porting the housing. There is actually a fair amount of data on IWG housings on other engine platforms, just google 8374 IWG BMW creep. Its really simple, if you want to run low boost, just port the turbine housing. I recently did one by hand, as the machine shop I used in the past went out of business. |
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