Turblown

iTrader: (12)

If you are using s4 t2 rotors it will not be as responsive as an engine with s5/6 rotors.

lOOkatme

iTrader: (19)

I don't have HARD data. this is all from personal opinion and from my experience at 6,300ft above sea level which effects spool times and what not.

Speedjunkies car is set up for spooling the turbo quickly outside of his monster exhaust ports which lead to his engine going out shortly due to damaged apex seals (from the ports). He has a short runner manifold and the turbo sits low next to the engine with dual external wastegates. He has a smaller sized V-mount intercooler with 2.5" piping, fitted with a larger filter on the intake right next to the V-mount. He runs water/meth and ran his turbo at 24-25PSI. His engine was spooling in the 2000's rpms and if he gets into it, he can spin the tires loose in the mid 3000rpms in 2nd gear from what I remember. His car pulled hard to redline, but the acceleration would lighten a little around low to mid 6000's rpms. It's not like a brick wall or anything like that, it just doesn't pull like my GT3574R does up there. mine comes on less harsh down low and slowly builds all the way to redline.

Whichever turbo set up you decide on just shifts power up and down based off the size of the turbo since most of the technology is the same except for maybe the EFR's lighter hot side which helps spool the turbo up.

Also, tuning makes a difference and people need to decide what they want from the car. I choose to have a little less spool down low with a tune that is leaner in the cruise cells for better mileage when doing long cruises. Others want more performance and worry less about MPG, run richer AFR's down low (say 13.5) in cruise cells and spool is much better at this AFR which drives more exhaust gases to spool the turbo. Speedjunkie had a lot more aggressive tune AFR wise than mine and spools like a beast. The downside is his turbo spools a ton cruising around going up and down the hills here and on the highway that he eats through his water/meth tank pretty quick. That is how much this turbo spools in the lower 2-4K rpm range.

In the end I like my turbo and I like his. Mine is great for hitting the mountain roads up here when the air gets super thin and the roads are wide open and fast. His is amazing for a street car and I love how you can catch a gear higher and drive through the corners....its smooth and the car responds so well, so quickly. I think both turbo's EFR7670 and EFR8374 would be great to run. I will be in a 8374 soon and see how it performs. I guess it all depends on what you want out of the car. Sometimes I personally wish I had a 7670, other times I am content on what I have cause I can cruise without boosting much, then bam hit it when I want to. On the other hand, coming around a slow corner and in 2nd gear in the EFR7670, you can just LEAP out of the corner like a boss going 15-20MPH, and if wanted lay a damn patch of tire marks just blipping the throttle down without clutching it.


Keep in mind that we are at altitude, those closer to sea level will probably be better off with a larger EFR8374.

Turblown

iTrader: (12)

Porting has the biggest affect on response and where the powerband is. Stock vs large ports generally shifts the response up to 1000rpms.

lOOkatme

iTrader: (19)

his rebuild will have stock ports.

silverTRD

iTrader: (37)

Isn't there porting that helps spool? Sean at aspec said in a thread that opening up the exhaust a little bit can help increase spool. I think that's what he said, I wish I could find it now.

Vicoor

The short answer to that is yes, but it can be somewhat complicated.

Most porting is done to help peak HP. This is not particularly conducive to helping spool.

If, however you work the porting with the strategy of increasing spool, then it can definitely help,

Think of porting more like a cam in a 4 stroke piston engine. You can get a cam that has lots of lift and duration for peak HP which isn't very good for a turbo. But if you get a cam designed to work with a turbo you can get the most out of your turbo.

ItalynStylion

iTrader: (1)

Not sure if you were talking about someone else or not but my rebuild will be a street port rebuild.

Also, I'm leaning towards the GTX35R as my turbo of choice thus far. Been comparing a lot of different ones but I think this one is likely best for my power level and isn't as expensive as the BW turbos.

Turblown

iTrader: (12)

A gtx3582r with a t4 1.06 housing is more than an 8374 efr http://www.turbosource.com/Borg-Warner-EFR-8374-p/ts1-03-83740.htm.

BLUE TII

iTrader: (9)

Isn't there porting that helps spool? Sean at aspec said in a thread that opening up the exhaust a little bit can help increase spool. I think that's what he said, I wish I could find it now.

Yes, opening the intake port earlier for more overlap (air and fuel into the exhaust) and opening the exhaust earlier (increases manifold burn) both increase turbo spool.

For instance the Alpha 4C production car uses "reverse V-tec" where it is on a high overlap cam down low for spooling the turbo and then switches to a low overlap turbo cam up top to keep from losing its boost out the exhaust for more turbo power on boost.

Granted, its easy to screw this up as any increase in runner volumes is going to lose you low end power from lower velocity.

Late closing intake and exhaust and huge ports is what kills low end power in the rotary.

jacobcartmill

iTrader: (6)

i've had several single turbo setups over the years, and the EFR 8374 turbo (internal wastegate) setup is by far the best one possible for what i'm doing.

^more on what *i'm* doing:
my car is a weekend/track car running low boost (~11-12psi) and making ~350whp (it was 338whp on a dyno dynamics, ~380whp dynojet). it would easily do over 400 with the boost raised a few psi.

the car has seen 5 track days and i have absolutely flogged it at all 5 events. i've been to 3 track days with this turbo setup, including one in 95*F+ 45% humidity weather in alabama and the turbo and internal wastegate have had no issues. these track days are over 100miles on track and ~2 hours of tracking.

i am using a turblown shorty (IWG) manifold and i made all the hard lines and have a custom downpipe and oil feed and drain. (it's similar to the full turblown kit). i'm also doing some changes to make a cold air intake and new intercooler setup, which you can check out in my build thread if you're interested.

i would much rather have this turbo setup than a GTX35R, and i'd recommend getting the internal wastegate due to its simplicity and reliability, unless you really like the chainsaw 2-rotor wastegate vent sound, which i find horrifying (and don't even think about plumbing both wastegates back into the downpipe).


also, i saw a post on the previous page of you mentioning *first gear being useless*. isn't first gear useless in a stock FD at 10psi? maybe you haven't driven a 400whp FD. you can easily spin 3rd if you're coming out of any kind of turn, and almost spin 3rd in a straight line. of course this is dependent on your tires, and you'll spin 5th if you're running on plastic 165s.

BLUE TII

iTrader: (9)

Basically the same as stock twins, with more simplicity, less power 1,000-2,000rpm and the ability to run higher boost (but not really make more power so what does that matter really?).


Actually, running higher boost should yield more low end to midrange power than the twins can muster- so it might be good for something. We shall see.

Well, I melted a dyno strap so I didn't get my full tune yet, but I will say that the EFR 7670 will be THE monster midrange turbo.

I did make 369 FT/Lbs at 3,200rpm @ 28psi boost.

As predicted the full pulls we did on low boost levels were pretty low HP. 275rwhp on 11psi wastegate and 308rwhp on 14psi. It feels even slower than that driving as power never "comes on".

We will try to get full high boost pulls this weekend. It looks like it will make great low/midrange torque and then take a dump between 5-6,000rpm.

WANKfactor

iTrader: (1)

Why is that..? because its just fiddly to do, or other reasons?

lOOkatme

iTrader: (19)

Same results as speedjunkies. Massive power in that 3000's rpm. It is a complete midrange turbo and spools like a beast giving up some top end.

vrx8

iTrader: (18)

HP at 28psi ?

GrossPolluter

iTrader: (1)

That is good to know you are having good results with that turbo. I was afraid rotaries would have issues with the internal wastegate not being big enough. No boost spikes or anything?

I have a hookup on garrett turbos. I'm wondering if any of the garrett internal wastegates would also work on a rotary. I don't even think they offer an internal wastegate for a gt35r with a t4 exhaust flange

Turblown

iTrader: (12)

Keep in mind that comparing peak hp is not apples to apples.

An efr or any small to medium frame turbo run at high boost will make a ton of torque but relatively low peak hp.

I built a stock twin turbo car that made 289rwtq/300rwhp and it ran 11.9 in the quater. It also beat a single turbo fd making 350rwhp.

Peak hp does not necessarily indicate how fast a car is.

Just look at how fast the efr roll racing video car is. It only makes around 500rwhp.

BLUE TII

iTrader: (9)

HP at 28psi ?

369ft/lbs at 3,200rpm = 240rwhp at 3,200rpm

3,200rpm is where we stopped the pulls as the car was climbing the rollers badly (due to the burnt/broken strap as we discovered). Have I mentioned how much I hate roller dynos?

The EFR 7670 flows 64lbs/min peak- I would imagine that will be ~366rwhp on this dyno/engine as my 60-1 HiFi (~57lbs/min) maxed out at 334rwhp.

I am hoping to get on a dynojet on the 7th where it should just touch 400rwp *if* we are able to get ~360rwhp out of it on the dyno dynamics.

I feel this turbo is likely to make more torque than hp as torque will drop before 5,200rpm.

The car IS fast, but no longer drives like a rotary- I am not sure how I feel about that. I will decide after I auto-x race it some.

Turblown

iTrader: (12)

Does your turbo manifold allow enough clearance for the bigger 8374, or is it placed like this;

FD3S Short Runner Manifold

If all goes to plan we are tuning an 8374 on the 4th to as high as the turbo will go...

BLUE TII

iTrader: (9)

As a base manifold I used an old HKS SS tubular. It is what was in the HKS T04Z kits before they went to V-band flanges.



Yes, it appears the 8374 and 9180 will clear in the FC with this manifold.

At most I would have to grind a flat spot on the front lower intake manifold runner where the compressor cover v-band is.

jacobcartmill

iTrader: (6)

it's quite complex (and thus expensive) and i could never get my vband connections to seal perfectly. it also made the removal of the downpipe (in general) much more difficult. i can now remove my IWG style simple downpipe in 5 minutes (no joke).

i have no boost spikes. i did have some issues at first with possibly having the wrong actuator, but now i've switched to the "medium boost" actuator and the boost shoots straight to 11-12psi. it did bleed off slightly (~2psi) by redline, but i'm using my haltech electronic boost control (and the EFR included boost control solenoid) to control the boost. i simply made a slight increase in the wastegate duty for the higher RPMs and the boost is totally solid right between 11-12psi.

here is a pic of the dyno (the dyno was reading about 1psi higher than my Haltech FWIW):



here's a graph with the axes matching:



here's more info (and a link to the post # in my thread) with more info comparing my EFR turbo to my previous Precision 6262 external-dual-wastegate setup:
(watch the videos to get an idea of the responsiveness). i can't imagine why you'd need the boost any more responsive than this 8374 .92 setup is.
https://www.rx7club.com/build-thread.../#post11704677

sleepydogz

iTrader: (3)

That's your user name so I can add you to my YouTube channel

sleepydogz

iTrader: (3)

You would need to open up both intake and exhaust ports
I would suggest going
street port!
That's what I'll be doing over the winter..
Now reading this am thinking of going with The 8374
The plan was gt35r but not to sure now..

lOOkatme

iTrader: (19)

8374 is a superior tubro in terms of spool and response, the GT35R is not a bad turbo (I have it on my car) but the lightweight hot side and little better exhaust to compressor wheel ratio on the BW EFR makes it better.

sleepydogz

iTrader: (3)

thanks for the info... but with the gt35r i would need an external waste gate too

Howard Coleman

iTrader: (6)

the GT35 and the EFR 8374 are very different turbos.

the GT35 is a small turbo.

the EFR 8374 is a middle size turbo

GT35

compressor size 6.38 average square inches area/ cast

turbine size is 5.17

EFR 8374

compressor size 6.62/ Billet

turbine 6.23......... plus 20.5% to the GT35

assuming both turbos can be driven to the 60% edge of their compressor maps...

at 14.7 psi boost

GT35 max power 420

EFR 8374 max power 460

at 20 psi

GT35 440

EFR 8374 527

EFR at 40 psi boost 580

one of the significant benefits of the EFR is the larger hotside turbine wheel. the more efficient the hotside is the lower the EGT which pays dividends both in and out of boost. less chance of warped apex seals.

the GT35 is a nice turbo but IMO the primary drawback is the smallish (80% of the cold side) hotside. since our motors require 30% more flow to make similar power to a piston engine and the exhaust is generally around 2-300 degrees hotter big hotsides work really well.

Borg Warner generally offers better hotside options. the garden variety BW equivalent to the GT35 has a 6.31 inch turbine. plus 22% to the GT35. OE build quality.

you won't go wrong w any of the aforementioned turbos but it will be important to pick a turbo that properly fits your objectives.

howard