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Havent gotten around to redynoing my car. Was gonna go hit the local dyno with a friend (the one with the black bmw in the picture) but never got around to actually doing it. To me there doesnt seem to be any boost issues. hits 15lbs of boost every time (the tuner set it at that) and does not spike. I did manage to go to a local SCCA Autocross event which was a lot of fun and the car handled it well. 2nd gear the whole time through the course and the turbo didnt have any lag. due to my inexperience driving skills, the car is a bit too much for me, haha. As of right now, my clutch fork broke on the bottom fork where the roll pin is. My new fork should be here today and can get the trans back on and driving. Missed the recent autocross event cause of that fork, but there is another one later this month. Only thing I need to get working is the IGN1A coils, figure out why it was breaking up around 6500 rpms. Will try to get that working and send it back to tuner for a retune. I paid money for that stuff so I want to use it, haha. Also I did upgrade my front brakes to Wilwood 6 piston race calipers my friend got me awhile back. Man what a upgrade, feels great. Not that I need them for autocross, but will be great when I go to the local road racing course.
Brakes look great! Seems like you are enjoying the turbo.
Thanks, yeah the turbo as of now is perfect for me. I thought i would need to go up in size, but after driving around with this 7670, its great match for me needs.
Hi there, did you ever get a 8374 to try in comparison? I have read all this thread and a few others and it seems you are still a big supporter of adopting the 7670 in recent times?
Here is my result. Got it tuned by Steven Kan at PRT Performance (great guy). Not sure how much his dyno differs in numbers than other dyno's. My 13b is stock port, EFR 7670 IWG, used the wastegate and recirculation valve it came with. 3 inch exhaust from downpipe all the way back to muffler. Unfortunately we had to put the factory ignition setup back in as my Ign1A smart coils was breaking up around 6500 rpms. I will have to sort through it and try to get it working. once I do I will send car back to him to retune. He took this tune up to 1 bar of boost. I have 550cc primary and 1700cc secondary injectors. I am running the Apexi Power FC, using the apexi boost control kit which comes with the apexi map sensor and solenoid. Tuned using the Datalogit program.
I would highly suggest investing in FC Tweak from Xavier Borg. Were your dwell setting setup properly in PFC? If you are using completely stock ignition system, you can probably pick up some power if you can get your Ign1A coils setup properly. FC Tweak can automatically set it up for you automatically. If your IGN1A is wired up correctly and you are getting break up, it could be that you dont have the right dwell settings. I have seen a few people just try to plug them in and go and run into break-up issues or end up cooking the coils.
An update to my previously talked about ign1a smart coils breaking up. So earlier this week i finally got around to looking into my smart coils. Relooked over my wiring, plug wires and grounds. Didnt see anything wrong. I literally just hooked everything back up the way i had it, went to go log some data runs doing 3rd gear pulls and had no issues. It all worked like it should, no break up. So i remembered when i was at steve shop (PRT) about a year ago to reinstall my stock ignition setup because of the break up issue with the smart coils, i noticed one of the wire harness connector plugs was loose from one of the smart coils. Im not sure if it was my doing or steve, becuase he did take somethings apart to look at stuff and may had accidently not clipped in that plug all the way when reinstalling, assuming he even romoved any of the smart coils, so could had been me. At the time i didnt feel like screwing around with it and just wanted my car tuned. So im pretty sure that was the problem all along.
Anyways, im waiting on Steve to look over my recorded data logs and get back with me on what he thinks my dwell settings should be at and if i may need to bring car back for him to tune it more. He said most likely shouldnt need a new tune, so we will see.
For anyone interested, this is my diagram i made for the smart coils.
Other than that, car has been great. Had lots of fun road racing it and autocrossing this year, cant wait till next season.
Hi there, did you ever get a 8374 to try in comparison? I have read all this thread and a few others and it seems you are still a big supporter of adopting the 7670 in recent times?
i have not yet. I probably wont go bigger even if i get my engine rebuilt and planned for street porting. The almost instant turbo spool with this turbo on the track is awesome and im only at 15psi boost, still have a ways to go up plenty. My friend has the 8374 and he complains it still lags a little bit on the track, though i havent driven his car so i cant speak an opinion for it. Could be due to his overall setup, im not sure and he is on e85. Im still currently on pump gas 91 octane.
The thing with the 8374 is that it builds boost instantaneously at any rpm you throw at it, but peak torque ends up coming on higher and that's probably why it feels laggy. At 10psi, my stock port 8374 was an absolute handful in the corners from the instant torque but the car was very lively in it. Bigger turbos promote higher cornering speeds to make them work much like any of Hondas VTEC engines so if you aren't driving through a corner fast enough, it might feel slow or laggy
Feel compelled to ask - proper track or autocross?
I have no idea. He hasnt driven the car in several years.
Quick update edit:
So I asked him again and he said it was only at autocross events the car didnt respond as quick and he said alot of times he had to keep the car in a lower gear than what you usually would. He said racing on road courses it was great and no complaints.
now the results/feedback make perfect sense in both cases, thank you
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No problem. I think another thing that my be contributing to his set up in a negative way might be his turbo manifold. I think whoever welded it for him stuck with 2" runners all the way through. I tappered my runners from 2" to 1 3/4 or 1 1/2, dont remember off top of my head, like turblown has their manifolds. Im not sure how much that affects things though, i didnt read up on it a whole lot. He is running a huge intercooler aswell, again not sure how much that would affect things.
for track/continuous WOT and with a 1.05 AR housing it’s spot on for an 8374 imo, doing what you suggest along with the 0.92 housing is going to produce a much better autox type response
of course it just depends, but I’d rather have the 1.05 housing with the 7670 even for autox, running flex fuel or race gas with the boost jacked up just like at the beginning of this thread. My feeling is the 0.92 IWG is likely to have excessive emap if pushed hard. I might consider it by wiring or welding the IWG shut and putting external WGs on it, but it still is going to be limited compared to the 1.05.
the tapering thing plays more into piping length and number of bends. Running small diameter for long length and multiple bends is going to compound, but the difference with short piping with few bends is much less. The circumference of a T4 port is roughly 1.875” (1-7/8” ID). If you taper it more than that the velocity increases, but how far will it actually carry and matter when it hits the larger T4 port opening and then expands before tapering again in the volute?
it doesn’t really get discussed on here much, but I really question making the piping any smaller than 1.875” ID into a twin scroll T4 housing for that reason. However, the one advantage of going down to 1.5” pipe size (Sch. 10 - 1.682” ID, Sch. 5 - 1.770” ID) is when space is limited and/or the goal is as direct and short as possible. Because the 1/2” shorter radius helps a lot for that goal. In that regard, if the piping is short with minimal bends then the magnitude of flow restriction with the smaller ID ends up not being that significant.
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Got my car dynoed at a friends shop on a dynojet 248x. He just got his dyno running. He is still working on the room itself though. Steve got back to me looking at my logs and suggested i use the 3.5ms dwell settings and said the data logs still looked good but a bit on the rich side up top. So my friend leaned it out for me some today. I didnt want him tuning it too much cause he doesnt tune rotaries and is not familiar with datalogit software. Overall i am satisfied and cant wait to hit the tracks again!
So the attached dyno graph with all the runs was when my friend made slight adjustments to my tune to lean it out some. Also he didnt have his dyno setup right for the rotary engine for rpm/torque. The last graph was the final dyno run and he got the dyno settings figured out. also attached is steve's tune for dyno comparisons.
Video from my facebook: "Edit" well i cant get the video to show up, sorry...
I was thinking it's perfect for most that currently prefer the 7670. Less limitation with spool still better than the 8374. Maybe better for auto cross than the 8374.
it’s hardly a limitation for this most recent one being under 320 whp (~43 lb/min compressor flow).
It’s an interesting idea to consider. Ideally in an autox application you’re looking for 450 - 500 whp peak before traction limitations get really ugly. So maybe in theory the spool is quicker with a 70mm turbine, except it now has more MOI and flow work from the larger 83mm compressor wheel to overcome and power. Which around ~2.5 Pr the turbine flow is peaking and emap is going to start kicking in, likely to onset sooner with the larger compressor wheel.
AGP does offer their own 1.25 A/R divided T3 EWG option for the EFR 70mm turbine though. Matchbot lists a 70mm 1.22 A/R on the same turbine flow line as the 74mm 0.92 A/R. So the question becomes how much will the spool be affected and how much boost is required to get there compared to an 8374.
The other issue; still to this day some of the AR listings in that range of Matchbot are pretty messed up from when it was first released over 6 years ago and nobody at BW seems to care enough to correct them. So it’s hard to be sure how accurate or trustworthy that type of “on-paper” assessment is even when using their own data.
saw some interesting EFR results on a Subaru WRX STi recently that made me think about this thread.
they were using an EFR7163 and thought it was maxed out. Somebody told them the SX-E compressor housing option was more efficient than the EFR housing with integrated BOV and they should give it a try. The results improvement was pretty surprising
Made me wonder how the 7670 and 8374 results might respond to same. Mainly because a lot of people seem to use not having to buy and install a separate BOV as an EFR “plus” point. I can appreciate that, but on a MAP system at the cost of noticeable performance it might bring it into question. I never would have thought it would be that much difference, but am not sure how valid it might be elsewhere with a different turbo model/application. EDIT: SX-E cover is shorter, but larger diameter due to increased A/R. So there needs to be sufficient clearance to swap one in.
04-12-21, 01:33 AM
