I know you corrected yourself but still you said something interesting.

14 psi at 2.5K rpms and sequentially... First stock turbos come on line at 2900RPMS. For the purposes of a fully stock car, sequential boost is as follows
2900 - 10 psi, 4400 - 8 psi, 4500 - 10 psi, 6900 - 8 psi until redline (with precat, cat, ect).
Second the higher the boost, the exponentially harder it becomes to control the transition and top end boost level. There is a reason why most people who boost above 13 psi on stockers go non-seq.

 

I know its been a while for me but my fd got 10psi well before 2,900rpm. I saw full boost at 2,500 with the stock cat in place and aftermarket downpipe. Now I know every car is differenct but, my twin setup ran flawless. Another local fd was built by Rotary Performance and it retained the stock twins. I drove it once and it was running 12psi and hit that psi below 2,500 with full exhaust and blew my car out of the water in terms of boost response. It was the 1st modified fd I ever drove and I will never forget how responsive that car was off line. No matter how gingerly I drove it, it just kept wanting to boost. Had I not went 20b, I would have rebuilt my 13b exactly like that car was built. It was one torquey ****.

 

Boost Test

I have had two FD's in my time (the one I have now I bought straight from a dealer in 98) that when purchased they had perfectly working boost responses. To say the least they both jived with the stated boost pattern.

Ultimately I can't speak regarding your experience, but it sure seems that it differs from the norm.

 

I don't see the use of comparing a show room stock sequential FD to a built single FD with a responsive turbo.

A single will never be saddled with the stock precat, stock airbox, probably not the stock catback nor even cat.

The stock precat and catback really kill spool.

IMO, optimized stock sequential twins (intake/exhaust/IC/Etc) is what we should compare to as a single will have all that stuff.

I would agree that from idle to 2,000rpm sequential is going to be darn near impossible to match with a single that can make 400rwhp (as stock twins can).

I think from 2,000rpm up the new tech on the 400rhpw capable EFR 7670 might be able to match a built sequential set-up based on how the 500rwhp capable EFR 8374 was able to match built sequential spool by 2,500rpm.

 

I have ridden in speedjunkies car with dual wastegates, short manifold, V-mount with 2.5" intercooler piping, 4" intake, etc, etc, etc,

The car rips like no other at any rpm. There is no lag at all at 2000rpms. I am willing to bet there is probably a 100-150WHP difference at 3000-4000pms between this turbo and stock.

My GT3574R spools fast and probably makes around 200WHP at 4000rpms. I am willing to bet he makes 200WHP at like 2500-3000rpms. His is rediculous. The efr7670 turbo probably makes more power by 4000rpms than a stock system can make anywhere on the curve. I bet the 7670 makes the same whp at 2000rpms-2500rpms as the stock sequential does at 3500rpms. Obviously these are just guesses.

 

How hard would it be to use 6258's as sequentials?

 

I love my 99 twins. I really cant put down more power down low than i have now. My car was a hand full at auto-x last week. I could easily overpower my tires in the corners on demand(warm 275 NT05's).

With a better control rack the twins work just fine.

Jason

 

Sequential twins will easily hit 10psi far before 2900rpms on flat ground in 3rd-4th gear. I tried looking on my phone but couldnt find the video. Off memory I think 14psi was accomplished by 2500rpms in 4th gear(most times this is the gear a car is dynoed in) on my personal FD even with the stock cat.

Comparing turbo response means nothing unless everyone is in the same gear on a flat road. Admittedly the EFRs are doing incredible things and I can wait to see more dyno sheets in the future.

 

I assume you mean the 5862 Precision turbos? Either way it will be extremely difficult with any setup besides the factory to run sequentially.

Response doesnt always mean more power, it usually means a much better torque curve. Once again the EFRs are really shining and Id love to see a 5862 precision around 14-15lbs on a nicely setup FD as it should give similar low end response to the EFR setup.

Sequential is great around town but a small single is also a blast with less headache once sorted.

The temps on the twins will always be an issue for any racing besides autox.

 

How hard would it be to use 6258's as sequentials?

I assume you mean the 5862 Precision turbos? Either way it will be extremely difficult with any setup besides the factory to run sequentially.

I think he meant EFR 6258 in stock sequential exhaust housings as I had mentioned in a previous thread.

How hard.

Based on peoples perception and experience of how hard the stock sequential turbo system is to understand/maintain I would say damn near impossible for most people.

Personally, I would say not that hard, but time consuming.

1) Machine your stock exhaust housings to accept the EFR CHRA/exhaust wheels
2) Make oil/water lines
3) Adapt Y- pipe to fit EFR compressor outlets.
A) Cut EFR compressor outlets/weld stock outlet flanges on.
B) Cut/extend Y-pipe to match longer EFRs (like with BNR Stg III)
4) Make new turbo inlet tubes/filters
5) Solve the "little" issues that come up with these projects
A) Do EFR compressors housings hit LIM? (trim or space out)
B) Rear turbo inlet sure is close to firewall. (go straight back with it?)

 

Our efr 7670 iwg should in theory reach those same 8374 boost pressures around 500 rpms faster. That would be about 26 psi by 2700rpms !! We are shipping a lot of these kits out so I expect to see more results sooner than later.

 

Will a 7670 with the biggest 1.04 back end be good for ~425-450rwhp?

I really like the small packaging of that frame turbo for multiple reasons.

Its either just tried/true T04S which is cheap/easy or this one. Have to stick with a 35 frame/size turbo so i can keep my emissions in place.

Jason

 

I don't think it will get you that high. I think you would want the 8374 size.

 

8374 wont fit as its physically too big. Strict emissions here and have to keep my airpump/acv lines in place.

Any 35 frame on my hks cast mani does allow that stuff to remain in place.

Jason

 

Are you sure the 8374 won't fit with the turblown shorty manifold? It is mounted quite low.

 

Will a 7670 with the biggest 1.04 back end be good for ~425-450rwhp?

That should be the top end of what a 7670 can do as it flows ~65 Lb/Min like the T04B 60-1 and T04S and people have met your power goals on those turbos.

I have a stock hybrid S5 T04B 60-1 in the small HiFi housing (flows ~57 Lb/Min) and its just over 400rwhp at 17psi (might *just* meet your power goals at 20-22psi).

I am hopeful I will gain a little power going to the 65Lb/Min 7670 with larger T4 exhaust manifold/housing and more boost, but really I am after the response.

 

What sort of power and response would be expected from an efr7670EW 1.04 **** on a streetport at 1bar boost and 98 ron unleaded as opposed to, say a tdx61 1.0,,, or an 8374 for that matter?

Reason i ask is i currently have a tdx61, just got my fresh built engine back but and am thinking about going EFR and selling the TDX while it is unused.

 

EFR 8374 will support about the same power as the TDX-61 and has been shown to spool about 500rpm faster (full boost @ 3,000rpm vs 3,500rpm).

EFR 7670 *should* spool another 500rpm faster, but has lower power potential by 50-100hp.

@ 14 psi 7670 should do 320-380rwhp, the 8374 and TDX-61 maybe 10-30hp more.

Imo if you are going to limit peak power by running low boost you might as well maximize the power under the curve' ie EFR 7670 and work on the rest of the engine system VE to get toward the top of the expected power output.

 

The EFR7670 is a smaller responsive turbo, made for more lower end driving, autoX type stuff IMO. If you want more power with lower PSI, an 8374, GT35 type turbo's are great. They shift the power back up the rpms and have a little more power.

Both work great, tough to say what is "better" because one is better in some situations, the other is better in other situations. all the options I think are solid. If you have the money, EFR7670/8374 are the best options for turbo's. The GT35 TD61, etc are good on more of a budget since they don't spool as well, they are still great turbo's. I own a GT3574R. The EFR turbo's are whicked.

 

Thanks guys, yeah i might stick with the TDX61 since i've already got it and everything is fabbed up to suit, i cant really imagine having full boost at 2500rpm instead of 3500 being thaat much of an advantage to sacrifice free ponies up top. I'll see how this one goes, if it feels like it needs more transient response or a smoother/ more linear pedal/noise relationship i'll look towards the 8375

 

BNR stage 3's hit 14psi before 3k rpm

Borg Warner suggest you need to replace your clutch, ridiculous

 

If you are talking about our new unit( that I've only shared photos of on Instagram- the dual wastegate shorty equal length), that will NOT fit an 8374. It will only fit EFR 7670 EWG, GT, an T series turbos( anything using a TO4S compressor cover basically).