Boost Management / ECU Question? - 16PSI Stock Twins 4x 850cc Injectors
 

Can anyone review this setup and let me know if I am overlooking any key support modification that must be in place to run 16PSI on the stock twin turbos?

Intake Mods:
APEXi Ram Air Intake
ARC Stock Mount Intercooler Upgrade (Small)

Exhaust Mods:
Downpipe - No pre-cat
Racing Beat Cat Back Exhaust
Note: OEM Midpipe w/ Main Catalytic Converter is still in place.

Fuel System Mods:
850cc Injectors x4
Supra TT Fuel Pump 280 lph

Cooling Mods:
Koyo Radiator

ECU/Boost Management Mods:
APEXi Power FC ECU
??????????????????

Thanks for the help!!!!!!

I don't have direct experience with it, but I would think the stock main cat would be quite a restriction at those boost/flow levels.

I'd also say that the 4x 850cc injectors won't provide enough fuel as well. I have the same setup and when I'm at 13lbs on the track (road course) I regularly see peaks of 85% duty cycle.

I guess I'll just have to wait and see what KDR will be able to tune it out to without overloading the injectors. Dave @ KDR said 16psi would be doable but I wasn't sure so I posted for input.

Anybody else have experience with a similar setup?

Anybody care to suggest a different injector setup?

You will be fine with those injectors.

The question is: Do you really want to run 16 psi on your stock twins?
1. They won't be efficient at that level.
2. They will run really hot at that level.
3. They will wear out quickly at that level.

So what will be a safe level to run? 15? 14? Keep in mine the limitations of the relatively small (almost OE sized) aftermarket SMIC.

Run 13 psi, 14 when you want to push it. 15+ your better off with a boosted octane 93 < ?

Thanks guys! So just to clarify, the fuel system will not be at the limit at these levels but the turbo will. Good. Since I am building for *SP SCCA class I am limited to maintaining the stock twin turbo setup while being allowed basically unlimited fuel.

Will the PFC be sufficient for boost management????

+1, if you are going to be running 15+psi going to the bnr twin turbos or a small single.

Not an option for *SP SCCA class. But thanks for the input! It's very helpful to know what is safe for my turbos. :)

850 primaries on a PFC will require a lot of tuning to have decent AFR's under low load and idle.

What do you mean a lot? Would the AFR tend to run lean or rich if not address properly?

rich i believe

Does anyone know where I could track down a good "base" map for running 850's all around?

hmm listen to dave a kdr who has been buuilding rotarys when these people were in diapers or listen to some jackass on the internet who probably doesnt even have a rotary.

I take everything with a grain of salt. Don't worry about me. ;)

I've tuned a Power FC with larger primaries and made 386 rwhp on a single turbo car. I've also tuned an FD on stock turbos with 550/1330. The PFC has well-known idle control limitations with larger injectors that often require tuning trickery as a work-around (namely, setting the PFC for negative injector lag for the primaries and possibly disabling the ISC system).

Just do a search in the Power FC forum, I'm not pulling this out of my ass. If you want the car to run decently you can go ahead and throw the PFC basemap out the window if you go 850 primaries. I'm sure KDR can tune it, but they will run into the same limitations that everyone else does, namely that the PFC will not respond when you try to lean out the idle beyond a certain point.

To the OP, I would recommend you go 550/1680 if you have the money for the new fuel rail (and might as well get an FPR too), or 550/1300. You will probably end up putting in 1680 secondary's anyways if you ever go single turbo. If you do 550/1300 you could get away with relatively simple modifications to the PFC basemap. Avoid bigger primaries of you can. 850/850 is just the cheap route for people who can't afford 550/1680.

wasnt talking about u

I hope you were not talking about me either???

no not u adam ore anyone...just saying the op has daves advice yet wants to check with the boy racers of rx7club.com.

yep

I like to double check things out in advance before I commit to changes/installation. It's not that I don't trust him, just that he always seems to have a lot on his mind. I didn't think RX7Club was filled with boy racers. I have read some very intelligent helpful info on RX7Club.

so have you decided exactly what boost you want to run? if it's more than 14, i would look into a twin power. but, you might be fine. every car is different.

alright let me start from scratch. Dave's advice will be sound and proven. if he says 16 psi is ok then its. the problem, and a pet peeve of mine, is most of the people on here dont believe that you can do this. I dont want to see you fall into this trap of self fulfilling BS!They base this opinion on the fact that they read somewhere on here about some kid crying cause when he pushed 15psi the turbos and engine let go. well the issue with that is that the car was probably not set up correctly, was a piece of shit to begin with, used ebay parts and the kid was simply an idiot. however it is pretty proven that 14-16psi is completely fine. i want to see you get good power from your fd and listen to dave. but whatever. i;de like to ask the people given you bad advice why SPECIFICALLY cant he run 16psi? what is your PERSONAL experience that led you to believe otherwise? then maybe we can analyze your situation......how many miles were on the car when you bought it, who tuned it, did you have good boltons or cheap shit, did you choose to go the safe route and upgrade the injectors to allow for a margin of error meaning cooler weather, etc.... cause i know for a fact that when you do it right it works wonderfully and reliable. Or you can listen to other heresay artists. Lets think ..do u want to lsiten to a world renowned rotary mechanic and a guy who has run this setup for 5 yrs with zero problems or do you want to lsiten to some 18yr old brat that spent 8500 for his fd and thats on his third engine and wondering why his ebay setup isnt working and blowing engines. this last statenment isnt directed to adam just a generalization as that is what will be coming next. adam is a valuable member here.

and thats that..it was just a general statement based on my own experience of running this boost for a very long time. everycar is different. if you get a good tune, use top of the line bolt on parts meaning a good intercooler not some ebay crap, dave does ther work, and monitor your temps i am willing to bet money that you too will enjoy a very streetable and very fast stock twin fd for a very long time. these cars are fun as shit in a maxed out stock twin form with awesome response and can eat up 03 z06s like nothing...leave em!

yeah i;de look into the twin power too.

Funny thing is, today when I asked Dave about it he did say the turbos won't last as long running 16PSU. To play it safe, he said, 14PSI would be a much more appropriate. Not sure why he didn't clarify the risks before telling me 16PSI was feasible the first time. Like I said, he seems to have a lot on his mind.

Anyway, maybe I can get 2 maps on my PFC (can they do that?). One 16psi for serious autox competition and one 14psi for street and not-so-competitive autox events.

yes you can have a high low setting.

Thanks for the help guys! Sounds like this is a fairly promising setup if temps and injector duties are monitored closely.

Can you get away with using Water Injection per your auto-x regulations?

If so I would def look into that. I'd also think about adding a FPR, Twin Power, and Boost Controller.

I'm currently running a similar set-up to what you listed, pushing 1.1bar (16psi) at my higher setting with 850/850 injectors. Granted, I've got a FPR and have set the pressure up 10psi from stock. I'll see max of about 73%-75% IDC when I'm high in the RPM range @ 16psi. I don't remember exactly what AFR I'm running with this IDC, I've got the innovative LC-1, but was a retard and fucked up the Lambda sensor before getting everything associated with it wired in, so my current readings are all over the place (must replace that!). I know that I am running safe AFR's though, not leaning out or anything like that.

I would be leery of additional heat though... I'll regularly see temps at 40* celcius with a SMIC when I'm running 16psi. I've only really got on it once when I was running a pretty well modified Evo. My intake temps with the GReddy SMIC and modified stock IC Ducting hit 79* before we stopped playing. NOT COOL!


I don't claim to know more than anybody else on the forum. The guy that does my tuning for me is one of the best in my country, and water injection came highly recommended from him (got it, installing it and having my PFC re-tuned for it on the 10th, hopefully I'll pull a bit more power than I am now 325rwhp + 15-18% to compare with average US numbers).

40 degrees isnt bad at all in the summer. in fact thats pretty normal i think

def keep us up on how the water injection does and if there is a hp improvement.

Yeah, the 40 deg is with regular driving though, I should have clarified that in my first post =\ When I put my foot down solidly the temp climbs fairly quickly, I tend to keep to my lower setting of .85 bar as a result. I really only hit up 1.1 if I wanna mess with somebody ^_^ Also gotta keep in mind that I'm in the UK and ambient temps around here are much more gentle.

Will certainly post an update on the results of the water injection though.

I know that a buddy of mine (m4drx on MRC and FDUK) who is currently running the same kit (Aquamist 1s) can put his foot down and go from 50*+ to mid/low 30's in about 20-30 seconds while using the stock IC. I think he's only at 13 or 14psi though. I can't remember exactly what he's running unfortunately =\

If I could ask a question.... My understanding is that the PFC maps fuel using rpm and boost as the two data points for the coordinates, ie boost is on the y axis and rpm is on the x axis of the grid. IIRC, the base map has boost going up to 18-20 psi. So given my limited understanding, it seems to me as if you only need one fuel and timing map, whether you want to run 14 max psi or 16 max psi. Am I wrong?

Secondly, the PFC can be used to control boost, but based on my limited understanding, I wouldn't trust it to do it at those boost levels. I'd suggest an EBC to control the boost and then you could have two boost settings, one maxing out at 14 and another maxing out at 16. Frankly, if the idea is to save wear and tear on the turbo's, I'd consider having one setting with the max boost at 10-12 to use for street, then another setting for 16 to use for autocross. Again, someone please correct me if I'm missing something here.

I've known the PFC to control boost up to 15psi better then some boost controllers...

Dennis,

Thanks Dennis. I appreciate the info.

I don't know what limitations you're talking about. I followed Chuck Westbrook settings for 850cc primary, see attachment. Car idled right at first crank using 850cc primaries with those settings. no tuning trickery at all.

Not really. Some of us can't get rid of our ACV due to emissions and so have to resort to 850cc in primary.

My pleasure! Are you from WA as in western Australia?

Dennis,

In *SP class water injection is specifically allowed.

I would definitely consider running A/I than. It's cheap enough that there is no reason not to have it if you will be running those boost levels while keeping (mostly) stock configuration.

Water is allowed, not alcohol. I ordered the Deluxe kit from the RX7Store. :)