8374 iwg turbo pros and cons
 

I currently run a pte 1ar 6262 bb/divided manifold dual wastegate to atmosphere. Its a pretty good set up but i am always nervous about those dual wastegates and at 12 lbs of boost the engine sounds like i am going to break it. I am sure it is not going to break but all the noise from the two wastegates gives the car a different sound. At higher boost 18lbs it does not sound as different. Full boost is at about 3400 rpm but i keep reading the hype on these borg warner turbos. I also hear problems with boost creep. Are these turbos that great. Pros and cons please.

EFR turbos are the best thing on the market right now. They have IWG and EWG options. Which one you would choose has to do with your desired boost levels.

They have been proven to spool faster than anything else out there and pull just as hard as anything out there all the way to redline. They are, in a word - superior in every way.

I do not have any first hand experience with them. But, if it walks like a duck, quacks like a duck and 100 people tell you it’s a duck, then it’s gotta be a duck right?

Nick

Superior in most ways... However, I've yet to see pricing on repair/replacement in the cases where an apex seal decides to take an exit, aimed directly at the turbine wheels. Cost may also be a hurdle.

With that said, I've recently upgraded to an 8374 ewg and looking forward to getting the car running.

Jehan is probably right there. The cost of replacing a turbine wheel or a cartridge on one of these might be pretty expensive, but I would argue it’s not any more or less expensive than a GTX Garrett. Traditionally, BW’s have been on average less expensive than their Garrett counterparts, generally speaking.

Nick

I wonder
 

Can it hold low boost without over boost issues. I have a 4 inch downpipe. 12 psi low boost and high boost 18. I hear alot of people complain about boost spike. I do have a greddy profec turbo boost controller. Thoughts?

What’s your port? Large with a 4”dp I would imagine. I say no chance of holding 12 psi with an iwg 8374.

Ported
 

Jesus Padilla at Kilo Racing professionally built the engine. I know he did a street port but dont know how mild or wild that port is.

I have a greddys latest electronic boost controller. When you say no way to hold under 12lbs are you saying even the boost controller cant manage it?

Boost controllers cant make boost lower, only higher.

I am not a mechanic but if i understand it correctly boost controller controls wastegates which controls boost. I control how much boost presure my turbo pushes. Low boost 12 and high boost 18. Not sure why i could not do the same with a borg warner

You can only go as low as your wastegate flows. Lets say for example your current set up has 12lb wastegate springs and flows 12psi without the boost controller, the boost controller can only do 12psi or higher. Only way to go lower is to mechanically alter your wastegate set up, with softer springs, bigger wastegate, more exhaust restriction, etc.
People have been reporting problems running low boost on efr8375iwg. Solution seems to be porting out the wastegate volutes or intentionally restricting the exhaust.
I have a ewg efr8376 on my car. It is a very good turbo. But if your set up aint broke, dont fix it unless there is something about it that is really annoying you. Maybe look into plumb back waste gate?

I got it. My setup is pretty good. I do like the suplicity of the borg iwg though. I may feel a little more comfortable with my setup once i get a little more tunning done. With the two wastegates i always nervous that one runner may go lean while the other is good to go as far as afr. I am highly thinking of getting tune plus egt on both rotors done while tunning just to be safe

EFR turbos are the best thing out right now in my opinion as far as turbos go. Ceramic ball bearings, billet wheel compressor, titanium turbine, stainless exhaust housing are all far newer technology than many other turbos. We generally see 15 psi by 3000 rpm or sooner with a 8374 and can easily break 400 whp on pump gas alone. they tend to make more torque and a flatter curve as well. The nice thing about them is the wastegate, bov, and boost control can all be integrated. Internal wastegate versions are nice and quiet. Boost control is largely affected by manifold design. We have no issues holding 8 lbs of boost with our equal length manifold on a ported motor with a full 3" exhaust.

May be my next setup
 

Complaints about my current set up. Soinds like the car is going to break when i get into the boost between 4k and 7k in the rpm. Dual wastegates are loud maybe thats why it feels this way. It just feels hard on the motor although it may not be. Smell of fuel from the dual dumps inside engine bay. Complicated with two wastegates. Pros That angry sound on boost. Spool and power is great also and no boost creep. I love the way the borg seems to boost they sound so smooth and dont sonund like they are hurting the engine. i am leaning on borg warner iwg but i am on hold for the budget for this car. This year and next year have already been caculated on paint and suspension. Just doing my research so i may put it into the budget for 2019

External dumped wastegates are loud. No complete way around it., If you already have wastegates, a bov, and boost controller it seams expensive to buy a EFR turbo. But considering the cost of purchasing those components separately the EFR is actually a good deal as all those are integrated. You could always sell your existing parts.

Wieght
 

Is there any wieght savings with the borg iwg? Does it sit lower? Selling my setup right now is not an option at this point. I am sure i would have to wait for a buyer and although it is a custom aspec turbo kit i would also have to change my down pipe,re tune and install $$$$$. It is a budget thing at this point. My setup is only one year old. Does this system help with the smell of fuel in the cabin? I have heard a lot of pros are there any cons with the borg iwg?

Slightly less weight due to the stainless housing. You can save even more weight by opting for the aluminum chra. You will most likely need a completely new turbo kit. The EFR needs more clearance because of the external wastegate actuator. The discharge vband is also proprietary. A downpipe with a standard 3" vband flange will not bolt up correctly. A catless rx7 will also have some fuel smell, but this can vary significantly depending on the quality of your tune. Discharging wastegates under the car instead of behind it will amplify how much fuel smell you get in the cabin.

Cons?
 

Is there any cons besides me having to spending money

None that I can see. You'll get excellent response, superior transient boost, and a nice flat torque curve. Its the best street turbo out right now in my opinion.

It really sounds like you are struggling with the idea of having a really good setup versus having the best setup. If you're asking whether the EFR 8374 is better than your 6262 everyone is going to say yes. However, you already have your setup installed and working which should have a fair amount of weight in your decision making process. Why go through all the money and time and potential for failure to switch turbos if you would be happy with your current setup after plumbing the wastegates back into the exhaust instead of venting to atmosphere? It would not cost you much money or time to do that and if you're still not happy afterwards you can just start saving for an EFR kit

True
 

I think you are right. My setup is good but like most of us fd owners good is never good enough. I am fighting myself and trying to be happy with my descent setup. I do see myself changing setups in the future which hints the starting of this thread. Rerouting the wastegates is a smart option but i dont want to loose 25 to 30 rwhp. Damn fd owners. Lol

Wait, what?!?

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.

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://cimg5.ibsrv.net/gimg/www.rx7...578116198c.pngHere's how I'm doing mine.

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.

I switched to this from a dump:

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.

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

Ah, gotcha.... It threw me off because when I went from an atmospheric dump to re-routing my WG I also moved from a 3" DP to a 4" DP. So I didn't have an "apples to apples" comparison.

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?

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.

From first hand experience I have found boost control issues with the IWG 8374 are directly related to the design of the manifold, particularly the angle of entry into the turbine housing. Some manifold designs have the exhaust enter in such a way that it hits a wall inside the turbine housing instead of flowing directly to the wastegate and causes difficulty controlling boost. That being said, I have no problem holding as low as 8psi to redline on my 8374 kits regardless of engine porting or exhaust setup.

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.