^^
My experience with stock and street port rotaries with turbos is the smaller volume and diameter the exhaust manifold and turbo exhaust housing and the larger the downpipe the faster the response of the same turbo.

I believe this holds true until you get to drag set-ups with really big laggy turbos combined with engines with huge overlap. Then more volume, length and diameter in the exhaust manifold leading to the turbo can allow for more exhaust expansion pre-turbo where the intake/gas sucked into the exhaust on port overlap can expand and power the turbo. I'm talking T6 flanged turbos sized for 800+ rwhp here, nothing normal people think of street-ing.

If there is any way you can get a 3.5" or 4" downpipe in the RX-8 with the turbo do it.
The front mount placement of the turbo in the RX-8 is already terrible for spool in most turbo kits since you have a 90 degree bend in the downpipe right off the turbo.

If you have to use this style kit, try to find a 90 bend for the downpipe right off the turbo with as large a radius as will fit in the car as well- don't settle for these tight CLR bends most people use for ease of fabrication.

Try to use the style kit where the turbo is angled 45 deg in front of the engine for a better downpipe flow. Like the Turblown EFR kit.
https://cdn.shopify.com/s/files/1/27...g?v=1518640259

Attachment 749397

More realistic target, compared to all the super inflated numbers you see flying around these days. 8374 with re-routed external gates on stock ports. There's some power on the table, but this is true life.

Actually, those are very good numbers.

Mainline dyno is the #1 heartbreaker dyno which typically reads 15-18% lower than Dynapac/Dynojet. Not adjustable to fluff the numbers up like DynoDynamics dyno.

That 346rwhp Mainline is easy 400rwhp Dynojet which is great for what 14.5psi boost in my opinion.

My Renesis did better at same boost on that very same dyno (396NM and 405hp at 14.5psi) - yours seems low to me .

Not mine.

https://cimg3.ibsrv.net/gimg/www.rx7...cab4da95a7.jpg
Here's mine from a while ago. 8374 EWG 1.05, twin gate, shitty rich tune, about 16psi

Was not expecting to see HP drop off at 6.3k rpm on a 8374 - *** (oops, was reading the TQ instead of HP), my bad!***

That mainline dyno is our cast EWG 8374 turbo system with 3.5" exhaust and rerouted wastegates, stock port engine on pump gas. Tuner said he was super impressed actually.

15 psi @ 3400 rpm 339 hp / 285 ft lbs on Mustang Dyno. Initial tune on the new setup 93 octane without meth and a bit rich. Plenty of room to go. Self tuned. Very happy with the results so far, thanks Elliot and Shawn!

This is a large street port block, Turblown's Shorty IWG manifold, BW EFR8374 w/ turbosmart 10 lb gate and dual port BOV, 3" exhaust with RB single tip, Elite Rotary V Mount kit and a twin power running with 9's all round.

https://cimg3.ibsrv.net/gimg/www.rx7...db44eb81f2.png

How's your boost control? Lookin good.

Using Adaptronic open loop boost control right now. I swapped out the Turbosmart wastegate to a 10 psi spring and run 4 port MAC solenoid. Boost control is spot on right now across the rev range, just took a few pulls to dial it in.

With no boost control, boost comes on and settles at 10.5 psi. At around 4500 rpm it begins to creep to 14 psi by ~6500 rpm. This is most likely the reason the Turbosmart included spring is 14 psi.

You should use some of the ngk race plugs, makes a fair amount of difference in my testing. OEM gap is just too large. Nice work, glad you like the kit!

Which plugs would you recommend? I plan on turning on the aux injection and pushing up to 20 lbs of boost next time I hit the dyno (week or so). I know my limiting factor will be the TwinPower over time and hope to switch to the IGN1A coils shortly.

NGK R7420-9 leading, and -10 trailing.

To me the fact that the powerband is choked to 5000-6600 at which point the turbo falls off in a car that is supposed to run 6500-8000 rpms through the shifts at WOT as a STOCK PORT makes it a poor choice for the platform as a whole. You find someone with a turbo that holds through that range, you'll be getting your ass handed to you no matter how quick your spool is or how much you make before the plunge.

Skeese

Couldn't agree with you more. Peak power should be at least the redline RPM of a stockport...

3" Exhaust + Short Manifold + IWG + 0.92 A/R Turbine Housing = EMAP through the roof. Very restrictive on all fronts.

I'd think with a larger and longer manifold + 4" downpipe/exhaust + EWG + 1.45 A/R Turbine Housing that 6600RPM choke point would at least extend another 1250 RPM with maybe a 300 RPM loss on the bottom end. Widen the powerband... 200hp at 4000 RPM, I'm not okay with that.

I always thought the 8374 was the optimal for the ~400whp range.

Would it still fall off early if boost was increased?

Will the IWG version be even worse than this?

Is there something else holding this back? That chart seems much lower than how people generally talk about the 8374. Seems more like was people say about the 7670

And shouldn't power be greater than torque?

I agree something is definitely amiss and choking it up somewhere, but you might have missed that this is already an EWG setup with dual wastegates and 3.5" dump. IMO it's not the shorty manifold. There's enough data in this thread alone to show that the 8374 with the shortly setup has sufficient flow for an 8374 to continue building power well above 6600rpm, especially at only 14-15psi. Even if EMAP is not optimal, the empirical evidence is there to show it cannot be bad enough to choke the engine at 6600rpm. It must be something else.

I suspect exhaust blockage further down the system (eg collapsed cat, restrictive 3" muffler?), ignition breakup or something tune related. Could even be an intake restriction.

See my comment above.
It's different from what you see on the 7670 charts. The issue with the 7670 isn't the hot side. The dyno charts drop off at high rpm because the 7670 compressor runs out of flow on a 13B.

Why does the torque curve follow so closely to the HP curve here? In the dyno graph I posted a few up, my torque curve comes up as boost does, then mostly holds flat with the amount of boost.

It's because torque is in NM and power is in whp . Torque should be in lb/ft.

The reason torque falls off so early on the EFR turbos is because torque comes on so early.

If torque didn't drop off then the horsepower would keep going up and up.
Yeah, we would love that, but an 82mm compressor can only move so much air- so... you know, physics.

Does EFR 8374 make less peak power than GT3582R? Does it make less power than T04Z?
No, it just makes the same power earlier in the engine rpms.

That car is relatively tame. No problem to open the ports, dump the gates, and move that curve to the right if you want to.

Agreed.
I would add to this that i feel the torque wouldnt drop off so early if the boost was allowed to increase above 14psi. It falls off fast as the boost is kept (in my opinion) low-med around 14psi +/-. If the boost was allowed to increase above 14psi as the rpm climbed the amount of air into the engine would be greater and the to power would stay up aswell.

why so many insist on running low boost especially as the main tune is beyond me. Even on pump 91-93 with 50/50 spray you should be able to run 20-25psi so why not use the turbo for what it can do? Why not run low boost/high boost settings? All these turbos can run what 40psi? And yet we limit them to 7-14... I don't see the logic in that. All these newer cars are running 20-30 psi albeit direct injection on pump fuel alone and here we are fussing over going above 15psi on pump.
Use 91-93 with 50/50spray and turn that boost up then you'll see real numbers.