I have a 2004 6-port manual car. The engine will be rebuilt with upgraded apex seals and possibly studded, too. I have a Esmeril turbo manifold that will be at the center of my build. Yes, it's top mount. Yes, there are technically other "better" manifolds. I got a great deal on this manifold and I like the idea of a top mount kit, so that's what I'm working with. Now that that's out of the way, let's get started.

I have a fair amount of experience working on cars (I've done a complete "backyard" restoration before), but I don't have a ton of knowledge with turbos--and I think that's about to change.

Here's what I'm familiar with and know I'll need:
Turbo
Higher flowing fuel pump
BOV
Wastegate
Downpipe
Intercooler
Charge pipes
Air filter
Braided oil lines
Versatuner
OBD port for Versatuner
Battery relocate kit
Bigger fuel injectors

Things I don't know about:
Boost Controller
Turbo type (Pulsar G30-660 seems like a good choice)
Which intercooler (should I just find a universal one that fits and fabricate some brackets?)

I basically need help building my whole setup. I've see that with this manifold and older GT3582 (or similar) made 366 RWHP on 13 lbs of boost on 91 octane. I think 350 RWHP would be a great goal. Would really love to find someone that wouldn't mind being a mentor to me, so to speak.

 

Ok, been learning a lot the past few days. The turbo manifold is actually a T4 flange, and I don’t think half the turbos I mentioned were correct. The other ones mentioned will likely be too small.

I want a bigger turbo to work with the engine’s characteristics (higher revving). I think I’ll need a pretty big turbo to flow properly above 8500 and make good power, but it sounds like people in Puerto Rico pretty commonly make 350+ RWHP with a properly sized turbo. I’d like to shoot for 350-400.

I’m trying to work out what will work best with my manifold (being an open T4 flange).

 

Been mostly figuring this out on my own, but I'll likely be copying this build quite a bit. https://www.rx8club.com/series-i-maj...-build-268497/

I'll obviously be using the Esmeril top mount manifold instead, and will be utilizing meth injection (w/91 octane pump gas), as opposed to Curt's E30 fuel choice.

Current progress:
-Changed the 38mm wastegate back to the original Esmeril design that uses a 60mm wastegate. I think with a smaller turbo and lower RPMs, the 38mm would probably be fine, but since I'm gunning for ~400 RWHP, I figured I'd go to what Esmeril used when they made they 400+ RWHP run years ago.
-Cleaned, "coated", heat treated, and titanium wrapped the turbo manifold
-Purchased a Pulsar 6266 (.96 A/R). Will be here in a few days. This turbo might spool slightly slower than Curt's (4200 RPM), but should provide more top end power (or at least easier, more efficient power on the top end). I landed on this instead of the slightly larger 6466 I was recently considering.

 

Large turbo + little boost = medium wastegate needed.
Large turbo + lots of boost = small to medium wastegate needed. A too large wastegate on a setup that doesn't wastegate much will be hard to control, mandating a well tuned boost controller.

Small turbo + little boost = just leave a damn gaping hole somewhere because no wastegate will suffice for this setup.
Small turbo + lots of boost = medium to large wastegate needed.

Poor setup with lots of bends in the pipes, restrictive silencers, small intercooler = small(er) wastegate needed.
Good setup with 3" or above exhaust, no bends, no diameter reductions, somewhat free flowing muffler, huge intercooler = large(er) wastegate needed.

Lastly wastegates don't make power or reduce backpressure unless the path through them is so terrible that they need to crack open wide to flow something.

 

The switch to a 38mm wastegate back when these manifolds were sold was purely (from what I can tell) for ground clearance concerns on some lowered cars. As you can see, the placement of the wastegate is not ideal, so I believe this is why the earlier versions had the bigger wastegate.

 

For the fuel injectors, it looks like I'll be using either red / yellow (uncapped) / yellow (uncapped), or yellow / yellow (uncapped) / yellow (uncapped). Since the p1 injectors are only use during idle and light throttle, is there a reason why bigger yellow injectors are commonly used in the p1 position?

My understanding is that the SSV opening timing can be changed to open slightly earlier to fill any lean spots.

 

You can still get into boost and exceed the P1 injectors flow capabilities below the threshold where the secondary injector's stage begins.

 

That was my concern. The reason I ask is because I'm trying to figure out the logistics of some things after the engine is rebuilt.

I need to get the engine and new clutch broken in, but would like to have the proper injectors already installed, along with all the other turbo components if possible (to avoid having to take stuff back apart a thousand times. I'm thinking this would probably mean I need a base tune that would allow me to drive around a bit with the bigger injectors and get it to a dyno for actual tuning. I'd need to have the wastegate kept open to keep the turbo from building boost so I can safely break in the engine.

 

Pulsar 6266E (.96 A/R) acquired! That's the two biggest components knocked out! Next is probably going to be a few of the smaller/interim bits like the battery relocation and gauges.

 

Quick update going into 2026...

The biggest update/change in plans is I'm going to use my existing engine for the time being--with plans to rebuild/upgrade a different engine later on. The front rotor compression has increased slightly since my initial check shortly after acquiring the car a few months ago. I've since put about 1500 miles on the car and the compression went from about 87 psi (cold test) to 98 (warm/hot). Rear rotor is about 105-107. I've also decided to go with the Haltech PnP ECU, with a target of 12 psi on E30+ fuel (instead of water/meth injection). I'm hoping to set up a flex fuel tune so it reduces boost to a safe 8 psi with 91 (95 RON) octane/E10 fuel.

• Finished the battery relocation to the trunk. I added a 150A circuit breaker close to the battery and made sure it was properly vented, too. I've put 100+ miles on the car with it and all is well.
• Uncapped 5 OEM yellow injectors. Will be taking the best matched 4 for the P2 and secondary positions after sending them in along with a couple unmodified injectors to get cleaned and flow tested.
• Modified a new fuel pump assembly; melted relief valve shut and opened orifice to 1.5mm. Will be installing a DW300 and wiring kit soon.

Considering doing the radiator upgrade and intercooler installation next, but since I don't know where things will be routed exactly, I may hold off on that until later. Still needs lots of parts.

 

Did my best to input some numbers in BW's Match Bot. I'm not entirely sure my VE or BSFC numbers are accurate, but I'm trying my best to account for E30 fuel and flow numbers with my 6266 turbo. Match Bot estimates 459 (crank) HP at these numbers. The actual flow rate does seem a little low, though. Thoughts?

 

This is everything plotted on the 64mm compressor map from Precision, but my turbo is 62mm, so the efficiency islands will be shifted to the left slightly. (They don't have a 62mm map)


Please excuse my MSPaint skills

 

Most people, as in over 95%, do not know any better past "more is better". There is such a thing as too much, imagine watering a dandelion with a 3" fire hose.
The primary intake ports have plenty of fuel in them when both P1 and P2 are online. P2 is the one to go big on(uncapped yellows is plenty big, perhaps overkill), while P1 has absolutely no reason to ever be changed from stock.
Secondaries need to be at least uncapped yellows.

Surprise! When you need more fuel than aprox. 60% of what P1 can deliver, the secondary injectors come online. This percentage varies by RPM. No matter how unfortunate the injector choice, you won't be left without fuel at any time as long as the total capacity of the 6 injectors suffices the total fuel quantity needed.

 

I can see that logic making sense, but I have two concerns or questions.

1. Keeping stock primaries creates a big jump from 360cc/min (x2) to P2 which is 1000+cc/min (x2). My assumption is that this can be tuned to ease the transition, though?
2. We're never relying on the primaries alone when WOT and heavy into boost, but the P1 injectors do contribute to overall fuel flow in that scenario. It's not a massive difference though (~200 cc/min).

I suppose 2 is answered with your previous response:

 

The primary 2s are the last set to come online. It matters not how large the difference is between P1 and P2, or between P1 and secondary or secondary and P2. The real problem is dosing a little fuel with huge injectors. See the analogy with the fire hose. That's why you have a set with tiny flow(P1) and then the big guns.

 

So in your humble opinion, would you recommend stock red injectors for the primaries with my setup (E30, 350-380 RWHP, 12lbs max boost, DW300 pump)?

 

Brett had a good writeup with suggestions on boosted renesis injectors. LINK

 

Yea, that's what I've been referencing up to this point--it's pretty helpful.

 

No matter what I would never touch the stock reds. I value a good idle and driveability. On top of that they are a pain to get to if needed to be replaced...
The entire "gimme your 4 biggest fuel injectors" comes from the FD guys. They only have 4 injector spots and need lots of fuel. Far more than what we will ever need. More fuel, fewer injectors. I can see some sense there in putting enormous injectors in primary position since that's all you've got feeding the primary port. We are spoiled with 6 of them; well except the S2 and the 4 port engines... which I'd never suggest be boosted. So, we can essentially replicate any FD setup AND keep the stock reds in there for cranking, idling, street driving to an OEM-level of quality.

If you absolutely must burn some cash and feel good that you've swapped parts... buy whatever you want for secondary and p2. No matter how large, and I mean it. More info why that is: https://www.rx8club.com/series-i-eng...m_content=post
If anyone else has a better reasoning for why you'd want some 1000cc injectors struggling to hold an idle at 900-1000 rpm, surging up and down, rich to lean and back...

 

That makes perfect sense to me, and is exactly why I asked the question in the first place. I definitely wouldn't use 1000cc injectors in the P1 spots. I'd be using regular yellows (if upsizing at all). If the P2 injectors start fueling once the P1s hit 60% IDC, I don't see there ever being a lean issue in idle/light cruise situations.

 

I recommend changing the reds to yellow on a 6 port in these circumstances:

1/You have a turbo than can spool up fast .... EG 10psi by 3500rpm
2/You are fitting large injectors (600 plus) in Sec. and p2
3/You are running the stock ECU and don't have control over Injection staging

Reason is you actually can run lean briefly at around 3000-3400 if turbo spools fast, plus, when the two larger injectors kick in, tuning for correct afr becomes difficult due to the sudden increase. The stock staging does not handle it well.
Yellows in primary run perfectly with absolutely zero idle issues.
BUT .... as Ciprian mentioned, changing them is a real PIA and if you aren't mechanically proficient .... you'll probably end up creating more problems than you solve.

 

I have changed them before, and it’s definitely not my idea of a good time lol.

I will be running a Haltech though, so I will have more control of staging. I don't expect this turbo to fully spool until about 4000-4200 RPM.

 

That's wrong, because you're observing the opening of the SSV which always overlaps the secondary injectors coming online. Better said, whenever the secondaries come online, the SSV also opens. You need to provision a rich pocket before that happens(which, interestingly, Mazda didn't do - perhaps it doesn't mean anything for an NA engine). It's not injectors, it's the sudden surge in VE the engine gets when the SSV opens. This happens regardless of injector size for as long as the SSV is still operational.

 

I don’t know much about turbos on these cars, but I know about Arizona and the RX8. You probably already know all this-if you plan on any time under boost above 90 degrees ambient, plan on a second radiator, almost as large as the first, plumbed parallel, especially if retaining A/C. The stock system heat soaks above 90 too easily. Not surprising, since the factory decided on less radiator area and a much worse flow path than a 105 hp FB.

 

I will be upgrading the radiator, but as long as there’s enough airflow to the radiator, it’ll be ok. One of the problems with putting turbo in a car that was never designed for it, is people do things like completely block the direct airflow to the radiator with a front mounted intercooler. I will be using a proven set up, but I will also likely be limiting boost at a certain IAT.