What will help me get the absolute earliest spool and best transient response? Dual port wastegate actuator will help early spool, internal wastegate will help with transient response, so IWG seems like the best starting point. I've heard a 3.5" downpipe will help vs 3", exhaust size after the downpipe 3.0/3.5 doesn't matter much, is this true? Turblown manifold seems like the logical choice with minimal runner length.

What changes can be done to the post-turbo intake side of things that will make an impact? Throttle body mods or replacement?

I'm sure porting can have a tremendous effect, but that seems like a rabbit hole. Stock to mild street port should give the earliest spool? Wide responsive power band is the goal with ~450ish on pump

 

Well, you haven't told us exactly what you plan on doing with the car.
For circuit racing or street driving, you don't need to overthink anything and the turbo is plenty responsive overall with excellent top end.
If you're autocrossing, you have the wrong turbo imo.
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A few things off the top of my head would be something along the lines of NOS, pre turbo water injection, staying with a stock port, considering drive by wire, etc.

Intake air should ingest colder air from outside of the engine bay and different intercooler designs prioritize flow.
The IWG only spools faster because of the smaller exhaust housing. Even with a long runner and dual external gated manifold with the 1.05 housing, these turbos spin up plenty fast imo.

 

I use it as a 2nd car. Weekends, trips, hard driving but no track time yet. I miss the throttle response of N/A cars to be honest. I used to drive an S54 M Coupe, E30 with ITBs, S50 swapped E30, etc. This is the replacement. I also ride sports bikes.

Drive by wire is an interesting idea. How could that help? NOS seems overly complicated for road use just to spool, but a valid idea. I'm already running water injection post-intercooler, will pre-turbo have a noticeable effect?

Mild street port currently, 1 bar non-sequential. No plans to open the keg compression is decent at the moment. Can't really take back a port job anyway..

 

If you run throttling on the secondary runners below around 4000rpm it will actually flow more air, make more torque and spool the turbo up quicker. Minimise exhaust manifold runner volume, cold air intake, large filter area, lower temperature thermostat and fan switching points (low 70s Celsius thermostats are available). It's all marginal gain stuff but is multiplicative. Staging runner throttles has far more potential benefit than messing about with a single drive by wire throttle. Look at what Mazda did to broaden the torque curve on the renesis.

It will never be like a bike.

 

I really think you should drive an Rx7 with one or at least ride in one and see if the response is fast enough for you.
I too thought like you previously but now I am more than happy with my 8374 with out any other spool aids.

 

Oh, you're still on twins. The EFR is basically taking what the twins do in sequential, but it's smoother, without transition, and the torque curve is substantially higher overall (Think a vertical shift upward).

Drive by wire can be helpful in the sense that you can tune your throttle blade opening in respect to your pedal position. So if you want a more responsive feeling, you can open the blade more for a throttle opening. I did it on my FD and it was fantastic. Not to mention it adds cruise control if you deleted it, deletes your IACV, you can run anti lag if you're crazy enough, etc.
Ideally, you can run tables to run more duty cycle on your boost solenoid in respect to the throttle blade opening to really eek out the most for your set up.
I do agree that seperating runners is better for peak torque (No denial in Mazda SAE papers), but the DBW is another tool in the box that can be used with modern tech.

The only catch is that even the most responsive boost set up will never be NA.

 

I would love to ride in one, but nobody in Thailand is running the EFR kits. All seems to be Airwerks, GReaddy T78s, older T04s, and G30/G35s. I know it will never be like a bike (my ducati has an intake kit, tune, exhaust, etc, it's amazing) but everything helps.

DBW has a lot of potential, definitely will look into this more.

Sounds like I should keep the stock throttle body and secondary throttle plates, keep the staging effect? Most people say throttle response is improved removing them. Is this a trade-off between low-end power vs overall throttle response? A larger aftermarket throttle will flow more, but will it negatively impact velocity and slow spool? Same trade-off again?

I will have the manifold, turbo and downpipe ceramic coated by Swaintech. Mostly for thermal management, but it may help spool.

 

Maybe the first step (if possible) is to go back to sequential and see how you like the throttle response.

 

I could, but I don't really want to re-tune for less power, seems like a step backwards. I'm close to maximizing this setup as-is without making large sacrifices. We all know the pros (and cons) for going single, it's the next logical step here, I bought the car with the intention of going single EFR

 

Parallel does not make more power than sequential. If you think parallel is better then something was wrong when you were sequential.

 

I bought the car set up in parallel mode, I've never driven a squential FD. This is also about the search for More Power Baby!

If I'm going to start switching things up, I'm going all the way. Already has PFC, dual coolers, v mount, walbro 450, IGN-1A, aftermarket FPR, 3" catless exhaust, water injection, full AN fuel lines, full Defi gauge suite. Going single means a fuel rail, injectors and a basic kit, and probably a clutch. I'm not starting with a stock car by any means. ~$8k single project, not $12-15k like most starting points.

 

Unless you have legal or racing class requirements the factory turbos are dead weights. EFR or G series is definitely the way to go.

 

No requirements other than reasonably reliable, and not overly loud. E20 tune (98 Ron) as it is widely available. I would like to run off-the-shelf components to make repairs quicker, nothing super custom. Street port.

 

I agree efr is the way to go and I also agree with using off the shelf or simple parts that are known to be reliable. With my tune the power delivery comes on really hard and I wouldn’t describe it as smooth. It’s set to 25psi to get the power up then tapers down to 15ish psi. It’s a blast to drive.

 

I gotta say, I really want to see the results of the variable A/R housing. 600-800rpm difference in spool is amazing, and worth waiting for

 

Try a basic 8374 kit before going to anything exotic to help the spool. I'm almost certain you'll find it great as is and you could dump a ton of time and money and hassle into finding what at most might ABA couple hundred RPM better response.

 

That is good advice, but I also don't want to keep changing things I should have done initially, and have to replace parts I've already bought. Simple parts for the best gains. Dual Port wastegate, 3.5" downpipe, ceramic coating, maybe Haltech with DBW. I don't want this to turn into a jackstand project due to overcomplication..

 

If you are not dead set on single, maybe consider the SP Bathurst twins that can probably get you to 450rwhp with the least changes, quickest response and probably widest powerband.

 

I went for a nice long hard mountain drive today, and the twins make sooo much heat, they have to go. I have a V Mount, water temps were 105c max, but oil temps at the filter hit 119c after a few minutes of full boost 2nd gear corners going uphill. Had to slow down for most of the drive, drive like a Miata, even had to pull over and let temps come back down. This really put the nail in the coffin for the twins, it's just too hot here to keep them. Big oil coolers have been added to the list as well now..

 

Are your oil coolers properly ducted?
With that front bumper (I might be wrong), I am guessing air is flowing around the coolers rather than thru it to cool it.

If it's not ducted you'll have the same high oil temp with a single.

 

They are well ducted. The openings on the Re bumper are larger than even the 99 spec bumper, and they are right against the coolers, however they aren't sealed on the sides so there is room for improvement. Lots of small tight uphill turns so there isn't a massive amount of airflow either way. The coolers already have -an lines, so it's a simple swap to bigger and better coolers and bracketry. Am I just being paranoid? Are these temps ok? They were climbing super quick before I let off.

Definity wrapping the downpipe asap, gets super hot in the cabin!

 

Experience here was more power, especially if all the manifold and turbo obstructions are removed. A big hole in the low and mid-range is the penalty on the other hand, which might explain the OP's desires.

Witnessed a 7670 get 300kw dyno dynamics around 20lb iirc, which is probably a typical 450 US figure if response was the main goal. 8374 is probably safer though, if limited to petrol. To take full advantage of DBW features, you'd need to be spending quite a bit more than the usual tune - that can really burn time.

All those temps would have me concerned, we don't see that here when air temps are high 30/ low 40 C and running at the track. I'd be sealing any and all heat exchangers to make all available air pass through.

 

Mountains going uphill means as much engine stress as a track, with less overall speed for airflow. Hillclimb style stuff is brutal. Fresh fluids soon and I'll address the ducting see if there are any large improvements to be made as-is

Yes my desire is to fill in some midrange, but still enjoy a rotary powerband. Limited to E20, available everywhere as a 98 Ron fuel. 8374 seems like it will play nicely. Don't really want to go through all the trouble of going single, just to have the same power I'm already making, so 7670 is out. Not sure where to get pure ethanol on a regular basis, so water injection will have to be enough. Sounds like 1 bar on 8374 will be a safe limit, and should be above the creep threshold

 

E20 98 should be ok for 20PSI. That's a lot more power than standard on a decent single.

 

Well that is fantastic news. Sounds like I'll be blowing up drivelines in no time haha. Tune for 18psi, no creep issues that high on the IWG, and be set with a decent safety margin.

Looking like DBW and Elite 2500 will have to wait. PFC is in the car now, and the local guys here tune everything with it, with great success. This is a ~$4k difference, with the added wiring and tuning for DBW. No wiring changes and easy tuning will help move this along so I can actually drive it: the real goal here. Good project for round 3: larger exhaust, stronger drivetrain and DBW / traction control when this gets "boring"