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My 8380 SX-E is def not as fast as an EFR. I've heard EFR spools at about 500rpm earlier. At VIR, I've found that you are constantly working the gear box to stay in boost. In what would be a 3rd of 4th gear corner in another car, I'm always shifting down at least 1 gear to get into boost if even only to get a good drive out of the corner before having to upshift. At this point, aside from tuning, I'm not dropping any more money on this build. It is what it is at this point.
I learned thaton the Porsche, it will leave the throttle open but kill fuel as part of way to keep the turbo spooled up ready to go. As a car enthusiast in general, this article on what Porsche put into the flat four turbos is a great read to nerd out on car tech. If only we could bring that spooling trick to the FD...
I met with Ianetti's son (who works with his dad) last weekend to hand over the seals. He also brought example of seals from other people who has similar issues. Net-Net from our conversation is that they will def analyze my seals to see if they can glean any info. His initial comment when seeing them was that they had way more wear on them than they should for only having ~700 miles. Based on what he told me, a bad batch is pretty close to impossible. He said the seals aren't made "as a set". He basically said if they made say 100 seals at a time (he implied they make more but didn't elaborate), the odds of them picking the 6 seals that were bad were bad and sending them to me is like picking winning lottery numbers. It can happen but the odds are stupid low. He was a nice enough guy and a little less overly passionate than his dad when it came to having an honest conversation. At this point, it is what it is.
On the bright side, I picked up my FD and drove her home (3 hours) from Rotorsports on Friday. So far, so good. I still need to finish the dyno tune with Nelson. He said "the last 15% of session is where I adjust things like throttle response , in gear transient AFR, , double check AFRs during up shifts 2-3-4 gear , and downshifting response.".
This build was with cryo treated Rotary Aviation Super Seals that Bryan recommended. I have a track day in just over a month so we'll be putting this build to test pretty quickly. I really hope she doesn't let me down.
I did drive the FD and the Porsche back to back on my favorite route. To sum it up, the Porsche is like having a video game cheat code in a driving game. The Porsche gives you the confidence to make you want to go faster. The FD dares you to go faster. The FD def has way more roll/body lean in corners. It also made me realize how much I dislike waiting for spool on single turbo. I really wish I had OEM twins....
Back in the 90's a lot of the cars had that body lean/roll because of the lack of things like traction control, electronic nannies, etc. It was just part of how they built cars to handle back then.
As for your OEM twins comment, that is exactly the reason why I hope to always have the stock twins... nothing beats their response. Simplicity... not so much, but a perfectly running twinturbo car is fantastic.
When I had 57/76mm To4B 60-1 on my FC I had to drive it like your Porsche drives itself to keep in boost.
Upshift with foot flat on gas bumping rev limiter to keep the throttle open so boost wouldnt drop and when tires started spinning I had to stay in the gas and steer around the wheelspin or again boost would drop.
Went to same size 57/76mm EFR 7670 and it was a complete change in character of the car.
If I dropped the clutch by accident with rpms too low drag racing I could just stay in the gas and it would pull so hard from idle rpm it still ran faster 1/4 mile timed than perfect 60-1 launch/flat shifts.
On upshifts I would now pull on the LS cars as soon as clutch was out instead of having to play catch-up at the top of the tach.
I could let off the gas and shift and the turbo would recover boost instantly and it was so much easier to drive because I could modulate the throttle to avoid wheelspin without losing boost.
What Im saying is- if you are keeping the FD, ditch the 8380 sxe as soon as you can afford an EFR 8370 and tune (and thats apparently right now since you can buy a new Porsche).
Haha. Yeh. I have twins (like actual ones) who just turned 1 and a 4 year old. I’m done throwing any money at the FD. The Porsche is the exact reason I won’t put anything else into the FD. Call it a midlife crisis car / FD isn’t reliable car but its because my other cars are paid off that the Porsche was even a possibility.
Haha. Yeh. I have twins (like actual ones) who just turned 1 and a 4 year old. I’m done throwing any money at the FD. The Porsche is the exact reason I won’t put anything else into the FD. Call it a midlife crisis car / FD isn’t reliable car but its because my other cars are paid off that the Porsche was even a possibility.
What Im saying is- if you are keeping the FD, ditch the 8380 sxe as soon as you can afford an EFR 8370 and tune (and thats apparently right now since you can buy a new Porsche).
it apparently needs to be stated again that unless BorgWarner releases something greater than the 1.05 A/R turbine housing for the EFR 70 turbine wheel then it’s not going to work well on a 13B engine. Because the peak flow limit for the EFR7670 1.05 A/R turbine housing is just too low for the larger EFR8374 compressor wheel.
That’s why I went with the SXE 262 hybrid, which is the S257SX-E fitted with the S362SX-E compressor wheel. Because you can get a 1.22 A/R turbine housing for it, which with the smaller SXE turbine wheel equals the peak flow of the 0.92 A/R 8374 turbine wheel/housing combination. It’s also known that the SXE compressor will outperform the EFR compressor of same size.
What seems to be lost on this subject is that the 1.05 A/R turbine housing is holding the EFR7670 back on a 13B as much or more than the compressor. Which is why it spools as quickly as it does.
An EFR7670 with 1.05 A/R turbine housing is not really any different than having a Garrett GTX3076R with 0.83A/R turbine housing, but if you proposed using that turbo combination on this forum you’d be shutdown in a heart beat. I tried explaining this in your EFR7670 thread and even posted an example of it using Jeff Kiesel’s 13B Sprite race car (which used the smaller still GTX3071R with 0.83 A/R) and it went right over everyone’s head.
Matching a larger compressor wheel to that same turbine housing/wheel combo is only compounding the issue. An EFR8370 with the existing 1.05 A/R turbine housing will be the approximate equivalent of having a 0.75 A/R turbine housing on an EFR8374 turbo. I bet if that was proposed you’d be one of the first to say not to.
An EFR8370 will, not maybe or kind of; **will** require a larger A/R to not have excessive EMAP on a 13B engine. It works on the equivalently-sized reciprocating piston engine due to having 30% less exhaust flow than a 13B.
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Rock that sxe until breaks, man. If you dont race pro, the sxe is ok.
The EFR has more responce , but the sxe should make same or a bit more power at the same boost level, just a bit lazy.
Nice Porsche too..
it apparently needs to be stated again that unless BorgWarner releases something greater than the 1.05 A/R turbine housing for the EFR 70 turbine wheel then it’s not going to work well on a 13B engine. Because the peak flow limit for the EFR7670 1.05 A/R turbine housing is just too low for the larger EFR8374 compressor wheel.
That’s why I went with the SXE 262 hybrid, which is the S257SX-E fitted with the S362SX-E compressor wheel. Because you can get a 1.22 A/R turbine housing for it, which with the smaller SXE turbine wheel equals the peak flow of the 0.92 A/R 8374 turbine wheel/housing combination. It’s also known that the SXE compressor will outperform the EFR compressor of same size.
What seems to be lost on this subject is that the 1.05 A/R turbine housing is holding the EFR7670 back on a 13B as much or more than the compressor. Which is why it spools as quickly as it does.
An EFR7670 with 1.05 A/R turbine housing is not really any different than having a Garrett GTX3076R with 0.83A/R turbine housing, but if you proposed using that turbo combination on this forum you’d be shutdown in a heart beat. I tried explaining this in your EFR7670 thread and even posted an example of it using Jeff Kiesel’s 13B Sprite race car (which used the smaller still GTX3071R with 0.83 A/R) and it went right over everyone’s head.
Matching a larger compressor wheel to that same turbine housing/wheel combo is only compounding the issue. An EFR8370 with the existing 1.05 A/R turbine housing will be the approximate equivalent of having a 0.75 A/R turbine housing on an EFR8374 turbo. I bet if that was proposed you’d be one of the first to say not to.
An EFR8370 will, not maybe or kind of; **will** require a larger A/R to not have excessive EMAP on a 13B engine. It works on the equivalently-sized reciprocating piston engine due to having 30% less exhaust flow than a 13B.
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You lost me here. I have an 8380 SX-E with .91 A/R T4 Twin Scroll Housing. I don't know if this is good or bad...but it's what I got...
You’re turbo has a larger turbine wheel. The A/R number is only relative to the turbine wheel it is housing, but in general a smaller turbine wheel will require a larger A/R value for the flow to be equal to a larger turbine wheel with a lower A/R housing. This is clearly demonstrated in the BW Matchbot turbine phi chart, which is just a turbine flow map expressing the exhaust gas flow in different units than lbs/min. After spending enough time on Matchbot comparing various results the lbs/min rates can be determined for those phi numbers on Matchbot.
You can see in the picture below that your 0.91 A/R is listed a few sizes above the 0.92 A/R for an EFR8374. The flow for the 0.92 EFR translates to about 28.5 lbs/min peak/flatline and your SXE turbine housing with the larger turbine wheel peaks/flatlines at about 35 lb/min. It also demonstrates what I’m saying about an EFR8370 needing a larger A/R turbine housing. Because you can see that in order for an EFR7670 turbine to be able to flow the same amount of exhaust gas as a 0.92 EFR8374 that it will require a 1.22 A/R turbine housing. Except you can only get that for SXE turbo because the largest A/R turbine housing available for that EFR turbine wheel is a 1.05. So my contention is that an EFR8370; an EFR8374 compressor on an EFR7670 turbine, with 1.05 A/R turbine housing is going to be limited on a rotary engine due to insufficient exhaust flow capacity of the turbine housing.
You can get that higher A/R housing in the SXE version of the 7670 though, which is why I went that route and then put the S362SX-E compressor wheel in it to make an S262S-XE which equates to an SXE 8370 with sufficient turbine flow capacity with a peak potential of 535 whp in a smaller package using a smaller turbine wheel. The smaller size of the heavy metal SXE turbine wheel won’t fully offset the weight/momentum difference of the EFR ceramic “74” turbine wheel, but it does bring them closer together.
But apparently it was just a typo and the post I was responding to meant say EFR8374 and not the new EFR8370 that was released near the end of 2021.
but you can see above other approximate equals between wheel size vs A/R;
and many more on the full Matchbot list, except they have the mid-upper range all messed up on the 70mm size. The 0.80 and 0.92 are correct, the next blank line above 0.92 should be 70mm 1.05, then 70mm 1.15, then 70mm 1.22.
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that’s a bit more subjective. Fuel type, application use, etc. On E85 fully supported in every regard it’s probably upper 500 - lower 600 whp just off the top of my head. For street gas with reasonable power, then lower boost, slower spool, AI, and extended WOT use for the occasional track day in mind. It can vary a lot. Opinions will vary on answering your question.
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Your 8380 SXE is a very good match for rotary in my opinion.
The only thing the EFR 8374 has over it is much better turbo response and recovery between shifts as well as somewhat better spool.
My personal experience as described above is the ball bearing center/lack of thrust bearing and light titanium aluminide exhaust wheel of the EFR line compared to a standard journal/thrust bearing inconel exhaust wheel of the same size turbo really changes the character of a turbo charged rotary.
My last reply on it; so you’d recommend an EFR8374 with a 0.75-0.80 A/R twin scroll turbine housing then? Because that’s essentially what you’re doing.
That’s why I went to lengths trying to explain and provide examples of the turbine impeller diameter vs. A/R relationship. Because even back say; 7 years ago, when members here were sizing up and comparing approximate average compressor vs turbine impeller area relationships, that didn’t seem to be well understood. I didn’t understand it back then either fwiw.
I appreciate all the feedback. As I stated before, this car is what it is. I have WAY TOO MUCH into this build. If I could start over, I’d go EFR but I’m done putting money into this car. I’ve got other responsibilities that take precedence over this car (like my 3 kids).
yes, I bought a Porsche but that doesn’t mean I will continue to **** away money on this FD. I’ve got $60k in this FD. Yes, $60k. I’ve become one of those “idiots” I secretly made jokes about who I met who did the same to their cars. This car will be a fun track toy. If it catches on fire, even better but im done putzing with this thing. Dyno tune it. Drive it. Enjoy it for what it is. If it goes boom, it goes bye.
I appreciate all the feedback. As I stated before, this car is what it is. I have WAY TOO MUCH into this build. If I could start over, I’d go EFR but I’m done putting money into this car. I’ve got other responsibilities that take precedence over this car (like my 3 kids).
yes, I bought a Porsche but that doesn’t mean I will continue to **** away money on this FD. I’ve got $60k in this FD. Yes, $60k. I’ve become one of those “idiots” I secretly made jokes about who I met who did the same to their cars. This car will be a fun track toy. If it catches on fire, even better but im done putzing with this thing. Dyno tune it. Drive it. Enjoy it for what it is. If it goes boom, it goes bye.
your car came a really long way, i hope the new engine is fine, and you can just enjoy it. ive seen ~60k FD's that were just stock cars with 60k on the engine, you at least got somewhere
