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Been a long time forum member but haven't posted in ages. I still have my FD RX7 (that I've owned since 1999) but hardly drive it anymore. I was thinking about the good old days when I was younger and dumped all of my money in my car. Back in the day I remember saving up until I could afford to do a single turbo conversion and ended up getting the Apex'i kit. I remember that back then, people were rocking a-spec, HKS, Apex'i kits, XS engineering etc... but it looks like those shops either went out of business or no longer makes any single turbo kits for the FD anymore...
Anyways, what turbo kits are forum members using nowadays? The only place that still sells a kit is the rx7store...Any other tuner come out with something new or does everyone have to piece everything together themselves now?
I'm in the same boat as you. My car has been sitting for 3+ year. I haven't been around to work on it. I was putting in a GT40R which was pretty awesome during the time, but now I'm reading all these crazy things about the EFR kits and now 2nd gen GTX as well. Now I'm wondering if it's even worth finishing. I have everything in, just need to put in the meth injection and tune it.
If you have the funds and swap from the gt40r to an 8374 the difference is night and day. The turbine wheels are half the weight and it makes a phenomenal difference in response and low end grunt.
We have a lot of dyno charts and vidoes on our parts website:
I'm still using the Apex'i single turbo from 2002-2003. It made almost 380rwhp on crappy 91 octane CA gas and gets full boost by 3,000 RPM. Is this outdated now? What type of numbers and boost response are people getting with the EFR kits?
What kit would you guys recommend for someone with a $5,000 budget with the goal of making up to 400 reliable rwhp on pump gas with good low end spool/response (laggy turbos would be a no no).
The Apex RX-6 kit is more like the EFR 7163 than the EFR 7670 or the EFR 8374.
I did the EFR 7670 on my FC and here are some vids that show the response. I hear the RX-6 is very good responding too due to BB and small exhaust side.
The EFR 7670 has a bigger 70mm exhaust side and I chose the 1.05AR T4 exhaust housing.
In this vid the Greddy Boost gauge is the lower one on the Mickey mouse ears gauge pod. 9 Oclock is 7psi, 12 Oclock is 14.5psi and it peaks over there at 3 Oclock at 26psi (when you hear the wastegates open).
If you watch a bit you will be able to see the boost gauge in some shots.
Our cast iwg 8374 kit is what you want. We have made 31 psi by 3400 rpms on one of our shop cars( 300rwtq at 3k rpms, 400rwtq at 4k rpms, 475 at 4500). Fastest response of any turbo system ever seen on a 2 rotor. Our cast kit is pretty much bullet proof too. We did over 100 of them just this winter.
You can call our office if you want to discuss more;
763 753 9939.
Yeah, I am talking in terms of power output Apex RX-6 is like EFR 7163 and Elliot is talking in terms of spool where the Apex RX-6 is like the EFR 8374 (but makes power like GTR3582R or T04Z).
If you are happy with RX-6 response grab the EFR 8374.
If you are happy with the RX-6 power grab the EFR 7163 with the T4 divided 0.80AR Internal Wastegate exhaust housing. It will peak at 400RWHP but the spool will be spastic.
Apex RX-6 used one of the Formula 1 turbos and EFR 7163 is one of the Indy Car turbos- so, yeah very comparable except for the technology advances.
Here you can see the excellent response of the EFR 8374 turbo on Armen's FD (though at lower boost).
Boost gauge is the one on the Left at the speaker pod-
EFR 8374 is the most popular turbo for the RX-7s.
It spools well enough for most anything and is big enough the torque doesn't drop off in the high rpms like the smaller turbos.
Why do most of these EFR kits have internal wastegates as opposed to an external? ? I was told by XS Engineering back in the day that external wastegates were the way to go....Are there any performance benefits or is it just to control sound
What type of fuel setup and ECU are people running with the EFR kits? Is everyone still using the Power FC or is that too old school now?
You're not far from me if you ever want to take a look at the EFR 9174 w/ Aluminum CHRA. Comparing it to a nicely built T4 Journal Bearing or factory S5 Turbo II is a quantum leap. Even of the top of the line Garretts from 5yrs ago...
Modern Computer Processor Company Comparison:
Borg Warner = Intel
Garrett = AMD
AX6 = PowerPC
I run a divided bb Aspec turbo kit pre 6262 1.00 dual external wastegate. Dont know how it stands up to the Borg warner but I do like it. 15 psi and it pulls hard and get full boost at about 3200rpm. I am curious about those Borg warner also. Wonder if you can hold boost under 15 lbs with full exhaust
I run a divided bb Aspec turbo kit pre 6262 1.00 dual external wastegate. Dont know how it stands up to the Borg warner but I do like it. 15 psi and it pulls hard and get full boost at about 3200rpm. I am curious about those Borg warner also. Wonder if you can hold boost under 15 lbs with full exhaust
I had a EFR 9180 IWG and could not. I had a 4" downpipe, 3" resonator, and a quiet Racing Beat dual exhaust. It would creep to 18-19psi in 3rd gear. It didn't matter if I had a 7psi spring on the actuator or a 14psi spring. I did add a restrictor in the catback which fixed it temporarily, but I couldn't keep gaskets in the thing. It kept leaking. I'm not sure if something was weird about my setup in particular, but I'll never know since I went to the dark side.
If you have the funds and swap from the gt40r to an 8374 the difference is night and day. The turbine wheels are half the weight and it makes a phenomenal difference in response and low end grunt.
We have a lot of dyno charts and vidoes on our parts website:
So tempting and my GT40r and HKS external wastegate are brand new though. So sad. =( Maybe I'll just tune it and run it for a little bit. Not sure if people even buy this turbo anymore.
So tempting and my GT40r and HKS external wastegate are brand new though. So sad. =( Maybe I'll just tune it and run it for a little bit. Not sure if people even buy this turbo anymore.
Thanks for the advice though.
I switched from a GT4088R to an EFR 9180. There is absolutely no comparison. The EFR stops the GT40 everywhere. It comes on quicker, is faster in transient, and makes more power. And with the IWG, you can flog it without notifying every cop in a 5 mile radius.
FWIW, I LOVE the sound of an external wastegate! Especially when you blow past another car trying to run you on the freeway! That said if there is indeed a performance benefit of having an IWG vs. EWG I would sacrifice the sound...However, XS Engineering did tell me back in the day that an EWG was the way to go because it results in less back pressure and frees up more power. Any thoughts on this?
Yes, external waste gate open vented is what you want for maximum performance.
Several thread on this forum over the years of people at the 400rwhp level that changed from open vented external waste gate to plumbed back in external waste gate and lost 25-40rwhp.
IWG is going to be the same or worse because of the small waste gate valve area.
On top of this with the larger exhausts (3.5" and 4") the EFR IWG have been shown not to be able to hold low boost on the rotary.
I think the IWG EFRs are an awesome option, but they aren't for every application.
I run a divided bb Aspec turbo kit pre 6262 1.00 dual external wastegate. Dont know how it stands up to the Borg warner but I do like it. 15 psi and it pulls hard and get full boost at about 3200rpm. I am curious about those Borg warner also. Wonder if you can hold boost under 15 lbs with full exhaust
Just had a customer hold 8 psi on the dyno today( 8374 IWG, full 3" exhaust). Hes been tracking the FD also, and it holds 10 on the track.
With the boost controller on he put down 396rwhp at 11psi on pump gas( large street port). It is on our FB page.
It seems to depend on porting, intake, and fuel/tuning. Some people get rock solid control all the way to 9000 rpm, some creep. It seems like the common theme is to run a full 3" exhaust.
03-08-17, 06:14 PM
