IWG vs EWG on Borg Warner EFR turbos
 

I'm very likely to get a Borg Warner EFR turbo and think the IWG versions offer significant advantages over the EWG versions, notably:
* Ease of installation (no wastegates, no pipes to exhaust, simpler manifold).
* Cost (the extra cost of the IWG version, a Turbosmart actuator and a beefed-up mounting bracket are less than the saving from not needing wastegates and screamer pipes or pipes to the exhaust plus the saving in a cheaper manifold).
* Reliability (there is no risk of burning out wastegate diaphrams).

The only disadvantage that I can see is that the IWG's turbine A/R of 0.92 is probably less suited to a 13B REW than the EWG's 1.05.

The IWG is the clear winner for anyone starting with a clean sheet. However, other people may already have a manifold and wastegates at hand and I've heard some people saying they prefer EWG's; how significant are any advantages of having the EWG versions?

IMO, there are no advantages running an EWG system.

The shorter more direct IWG manifold produces boost quicker and response time is faster. They are more reliable.

The only thing I can think might be an advantage of an EWG system is less restriction in the exhaust and also an open dump puts less strain on the exhaust, giving a little more top end WHP, but its at the expense of low end that an IWG would get. Unsure which would actually be faster in real life.

I have the 8374iwg on my fd. I chose it for all the reasons you mentioned. It's reliable, you can't burn out the diaphragm, it's a cleaner install etc. With that said, the downsides are you have to make or buy a custom bracket for the waste gate actuator (turbosource sells them). I experienced boost creep. It peaks out at about 24 psi on a cool day. It doesn't matter if I wire the waste gate completely open or set the boost controller at 20 psi. It still creeps up in the last 1600 rpm of the usable rpm range. To remedy this, I inject a crap load of water/method and tune for worst case scenario. When it's hot out the afr is fat, but I scrapped the stock ignition and went with the smart coils. It no longer blows out the spark. I'm making 500 at the wheels on stock ports. I am contemplating a half bridge but I don't know if the waste gate will handle it; another possible draw back. Other than that, everything is great. The power band is phenomenal.

There are 3 different articles on our blog about the EFR turbochargers, and a few of them touch on IWG vs EWG;

TurboSource | Turbocharged performance specialists & distributors

EWG allows one to run very low boost pressures, while the IWG does not. 95% of people see 10-11 psi on the IWG system( 3" exhaust open).

Lucky7Racing just dynoed our 7670 IWG kit with a full 3.5" exhaust and it held 10psi on a ported engine.

One is talking a 42mm wastegate(IWG) vs whatever you can fit on an EWG( for example our EWG manifold runs 2 x 40mm turbosmart wastegates).

Shawn, that's a very informative and useful article - thank you.

I'm looking to sort 2 different installations, one on an RHD FD and one on an RHD RX8 with a 13B REW conversion. Our power aims fell between the sweet spots of the 7670 and 8374 and we've therefore spent much time, research and indecision to finally decide that the 7670 is better for both of us. We're looking at max boosts of 15 psi because reliability is more important than a few extra hp; that article suggests that the actuators with the EFR 7670s will probably do and we already have e-boost street controllers to control them. If the TurboSmart dual port actuator will work with the e-boost street's 2 boost levels to give 2 boost levels then we may treat ourselves, particularly if it reduces the risk of our wasting our tuner's time. More research to do . . . . .

BTW I can't find the strengthened actuator plate advertised anywhere. Is this still available?

The only fly in the ointment is that I had a surge of enthusiasm a while back and bought 2 wastegates only to be let down on a turbo deal. Getting a manifold for the FD is easy but the RX8 manifold will require a bit of fabrication, where an IWG will make life much easier. I think the best option is to get IWGs and sell the wastegates once we're convinced we won't need them.

Our iwg actuator bracket is not a strengthened piece, its just that the OEM BW unit does not fit in the orientation of the turbo clocking with the IWG cast manifold. With an Rx8 setup( if the turbo is farther forward and up high like our Rx8 turbo manifold) then you do not need a new bracket. We actually just finished a prototype of a new adapter that will allow the OEM BW bracket to work for our IWG kits. We are still working on the pricing.

Any data to back that up? when you say reliable, are you talking specifically about turboblown's cast SS manifold?

Sounds like you need to leave the car alone IMO ;)

Someone who opts for an IWG over a dumped EWG does not want or need a half bridgeport.

I've built almost 200 rotary engines over the years...... I'd say 160 street ported, 39 stock ports, and 1 half bridgeport. There's a reason for that ;)

I choose the EWG kit because I wanted the bigger A\R and at the time I wasnt sure how controllable the boost would be with a large streetport/full 3.5 exhaust. I am only running pump gas without AI therefore I didnt want to risk having a setup which creeped past 16psi.

With that said, I am very happy with the EWG kit. Boost is very stable (esp after I installed an electric boost controller which also further improved spool) Only mod I made was re-routing the dump tubes.

Hmm what appears to be a better turbo, seems to have a slight drawback of controlling boost, forget about the IWG setup simplicity, boost control is important. (Turbosource) do u have any input on boost control on the 8374 setup (IWG).

Here is the thing.

If you are going to want to run low boost and still worry about optimizing flow with a huge 3.5 or 4" exhaust, low pressure drop IC, ported intake manifold/throttle body and 6" velocity stack to 12" long filter and/or crazy porting...

Get a good external WG set up and maybe 2" runners on the exhaust manifold.

If you are happy with 3" exhaust and 3.5" intake straight to filter or even just putting a muffler on the exhaust if it creeps with your optimized flow set-up...

Go ahead and get the internal WG set up.
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I did the external WGs on my EFR because I was paranoid about boost creep from my last turbo-set up, but I can totally see that internal wastegate and a little exhaust "restriction" (really, its called having an exhaust) would be fine.

On my last turbo-set up it was fine with 3.5" downpipe to RB 3" cat back, but no... I had to run full 3.5" turbo back and keep messing with it until it didn't boost creep.

I totally see how awesome, reliable and simple the cast manifold to IWG EFR set-up is, even if I couldn't bring myself to run it and "risk" boost creep (could just put a muffler on the car...). I would recommend IWG set-up to anyone.

Unless, I knew they were like me.

Dp

I just tuned a 7670 IWG with a 3" DP, 3" high flow cat, and 3" open catback. Held 6.85 psi through the rev range. I am dyno tuning it monday with and without the midpipe. It has a small street port that we did, and a FMIC( its also pretty cold out so it should be more prone to creeping).

Sweet :)

Externally Gated 8374 here. On a long runner Turblown Manifold. Car Rips... NO boost creep since I've had it. The IWG kits are solid as... especially if you don't like keeping an eye on things mechanically. My car see's the track only now a days...but with external gates.. comes maintaining them. Over 20 Events on the set up and you bake everything. Heat kills and I've roasted my gates which probably caused a diaphragm failure. Also, it IS possible to over heat WG springs. When you do that.. they lose their original shape...or Height that is. Which results in leaking gates. I havn't seen the Internal kits have any issues with this.

Each kit has it's place. I want my car to be as loud and in your face as possible. I also like throwing flames. And I didn't want to chance boost creep since I have plans of steadily raising boost pressures. To each his own... but one thing is certain. There is NO better turbo on the market than The Borg Warner EFR series!!

Ok iv'e pretty much decided to go EFR. The goal is NA-like throttle response, regardless (to an extent) of when max boost come on, eg, if there is nothing before say, 3500rpm, I'm not too worried as long as after that I've got near instant response in on/off throttle conditions.
Currently making 338 on a Dyno dynamics Dynotech on a streetport s5 with tdx61 0.1 housing. 12psi on donkey fuel, full boost at 3400, but only if ive been standing on it for a couple of seconds. Dont get me wrong, the turbo performs amazing, but anywhere below say 5000rpm there is some lag, where i was used to a 58mm hybrid with insta-spool.

The question is; should i go 7670 or 8374? IWG or EWG? If i go 7670, will i make the same power on the same fuel?
Is the spool up on an 8374 as good or better than a well designed 58mm t04 hybrid?

Is an EWG detrimental to spool up compared to IWG in any meaningful way?

The current manifold is quite a nice design (i think) and conducive to good spool and rock solid boost control. Might run water meth in future with more boost, but might not.

Last question, will an EFR fit here? See pics.

The EFR 7670 and EFR 8374 will certainly fit RX7 FDs and there are plenty of pics of installations on the internet, eg at Turblown and the EFR 7670 one below. The EFR 8374 probably needs a revised/new bracket for the IWG actuator and will also need an uprated actuator for high boost set ups.
https://cimg7.ibsrv.net/gimg/www.rx7...43c0b76f8c.jpg

Like any other turbo change, you will probably have to modify your downpipe and compressor outlet pipe. You may also need a new manifold.

Your aims, like mine, fit the EFR 7670 rather than the EFR 8374.

Spool depends on more than just the turbo and I've seen only subjective reports, no figures, on spool times so its difficult to quantify how much better the EFRs are. All the reports I've seen say that the EFRs are noticeably quicker to spool than the turbo they replaced.

^ thanks. A lot of work went into the manifold and twin WG routing, so would be hesitant to change it, although, if i did want to build another manifold it would be IWG.
Yeah, I'm leaning toward 7670, but will it make less power than my tdx61 on the same fuel that im currently tuned for? Limited to 338 @ 12psi safely on local pump gas (98RON).
There's not much room in there - its a RHD FB, wondering if the EFR will fit on that manifold.

12psi on 98RON (93 AKI for us Yankees) is very conservative. I have had no issues running 13-14 psi on 93 AKI and 9.7:1 rotors over the last 2 years. Water methanol is also cheap insurance. Run a small nozzle and a gallon of injectant should last you a week or more.

Is an EWG detrimental to spool up compared to IWG in any meaningful way?

EWG and IWG is not going to impact spool, but the manifold attached to the choice will.

Big 2" runner T4 manifolds will not spool as well as the smaller diameter runner Turblown manifolds. The larger runner just has lower gas velocity and less of the overlap air/fuel expansion happens at the turbine wheel.

However, I did use a HKS T04Z manifold (big, but short equal length tapered runners) modified for two 44mm EWGs on my EFR 7670.

Very fast spool. Very poor gas mileage since it is always spooling into boost with a twitch of the foot even on the freeway.

Still, it is still a turbo car. It has the same torque @ 3,000rpm and power as a 6.0 LS V8, but it doesn't have the same tip in throttle response.

You feel one powerband while the boost gauge needle dashes up to full boost (taking a fraction of a second) and then the you feel the second wave of torque as the engine pulls through the RPMs at full boost.

If you have driven an 6.0+ liter LS and that is the NA response and power that you want, put that engine in your car.

A turbo car is always a turbo car. From reviewing my data logs because I felt something I have learned the human brain can easily perceive hundredths of a second and tenths of a second can feel like an eternity.

^Except there's another factor to take into consideration... The fact that the EWG comes with a larger A/R....which the IWG does not. So your are right regarding internal vs external not affecting spool...but the size of the housing will have an impact as well as the mani=-)

Good point on the exhaust housing AR!

IDK how big a difference the T4 0.912 IWG and T4 1.05AR EWG is, but spool will obviously favor the tighter AR.

At 13.4 psi we made 375rwhp( dynojet) on an E50 flex fuel tune with a 7670 IWG Fd we built in house yesterday. That is probably 325rwhp on a dyno-dynamics in AUS FYI. That was through a high flow cat too, small streetport and a FMIC.

^ Thats pretty healthy. Stupid question; from a tuner's perspective, would 13-14psi on the 7670 be equivalent to 11-12 odd psi on my tdx61 in terms of how far one can go on a safe tune all other things being equal?

Im a little bit concerned by the 7670 running on the ragged edge after 6000rpm. Would pre-turbo water-meth injection provide enough Intake cooling to help shift the compressor map right?

Im asking because im agonising over whether to put an ewg 7670 on my existing manifold for minimal mods and $xxx's cheaper (and i actually happen to have a water meth kit and four jugs of boost juice on the shelf),
or redo the manifold and and half the exhaust and everything else, and get an 8374, which might be a challenge to shoehorn into my rhd 'bay to say the least.
Id prefer the 8374, but a lot more $$$ and effort.