wankelbug

I recently added a turbo to my 85 gsl-se engine 9.4:1 compression ratio. It is currently running on 12psi on a gt3582. I am wanting to push it to 15-16 psi chasing the 400hp numher. I am running at 10 degree of timing after 6psi, 93 Oct and plenty of fuel pump and injector. How far can I safely push the boost on this compression ratio motor without alternative fuel/injection? I am tuning to 11:1 afr after 10lbs. If it helps this is pretty much a purpose built drag car not a cruiser.

arghx

iTrader: (3)

I presume this is EFI, controlling fuel and spark completely. There are no carb's or locked dizzy's or anything like that. A lot of this has to do with how well you can control intake temps (compressor efficiency, intercooler, ambient conditions) and how well you can control backpressure (turbine housing A/R, exhaust restriction). Both are major contributors to knock.

Can you ECU post fuel maps, timing maps, and WOT logs showing AFR & Timing? Have you seen my boilerplate 9.4:1 & 9.7:1 compression timing maps (originally intended for Rtek 2.1)

wankelbug

yes i am running MS2v3 and will be able to post some timing, split and afr maps this evening. i am using a large water to air inter cooler. after an ice down my intake air temps are 55 degree and after about 10 mins of street tuning i was seeing 80's i typically keep tuning until IAT reaches 110 degrees then i take it back to review logs and re ice. at the track i should see 50-65 IAT under full boost (12psi) . my timing is i little more neutered ( if i am reading your table correct) i am @ 12.5 until 6 lbs and 10 degree after my cas is stabbed in stock location where base timing was set at -5 degree (yellow pulley mark)

my car is a 1970 vw bug therefore i dont have much downpipe/exhaust to speak of. the downpipe is 3in and dumped out the back of the car so maybe 4 feet total of exhaust without any muffler.

i will post some tables this evening.

thanks again for the input.

wankelbug

i have attached my timing, afr and split table

arghx

iTrader: (3)

are those intake temperatures in celcius or fahrenheit? where are they measured? Have you confirmed with data logs that you are achieving the target AFR? Maybe you should rescale your target AFR map for less resolution in vacuum and more resolution in boost. In terms of the spark, it's very... "distributorish" in the sense that you have a baseline timing value at a reference point (here about 7psi boost) and then add timing relative to that. From a knock perspective as long as your intake temps are cool you can probably get away with that.

However it's normal procedure on EFI spark tuning to have a gradient in the spark curve with RPM and boost throughout the whole map or at least most of it. See my example map I posted. I presume you also have an IAT compensation curve to pull spark when the temps climb. Can you post that? It's been a while since I've messed with MS2, but I have used MS3 somewhat recently.

The lower your IAT's and the higher the knock resistance of the fuel, the more margin for error you have with spark timing. So if you keep putting ice into the intercooler and doing single passes, it may not even matter. That's why you'll see piston engines on E85 with locked dizzy's making great times in a drag situation. On a street kind of application with broader use the refinement of the timing maps becomes more important.

wankelbug

Fahrenheit! i got a bad *** water to air setup, i am picking up my IAT from about 3 in in-front of the throttle plate. i was thinking about tapping the IAT on the manifold near the port since i am running an NA S5 manifold and it has some pretty long runners. i dont know how much my charge is being warmed by the heat soaked intake.

i am still doing some final tuning because my VE table is still a pinch rich, i have a wideband gauge and the data logs to verify the readings.

i am likely going to build 2nd tables for target AFR and VE so i have a lot more resolution throughout the spectrum. but i agree with scaling the AFR table to have more boost resolution.

i will post the temp based timing retard table this evening, i think it starts pulling at 150F IAT

i am trying to smooth out my fuel map around 2500-4000 rpm in the 35-50KPA range but i am fighting my injectors. due to my large primarys i cant seem to maintain a smooth cruising speed without either bogging (too rich) or surging (too lean) i may try dropping my base fuel pressure a few lbs this weekend and see if i can smooth it out and compensate the VE table to suit the changes. at 12psi of boost my injector duty is only like 50% so i have plenty of head room.

i may look into adding knock sensors and try to push the timing in boost a little harder once my ve table is 100%


in all reality the car will be street driven no more than 20 miles and trailored to dig racing events and the drag strip. street drive ability is not extremely critical to me but definitely a factor. the trans is equipped with 8th mile gears (4.86 R&P - 1.13 4th gear on 26in slick) so it is not fun on the roads.

Thanks for the input. and i will post my results of tinkering this weekend.

wankelbug

see attached timing retard table

Shainiac

iTrader: (7)

The lowest MAT value (150F) needs to be set to 0*. Any MAT below 150F will STILL have 1* pulled from the base timing value. I had a similar situation, but was pulling 4* at 150F and the ECU was pulling 4* EVERYWHERE. 1* isn't going do to much, but it's nice to bet getting what you think you're getting.

wankelbug

Thanks. I made that adjustment this evening. I rescaled the afr table for more resolution in boost. Tweaked my timing table some to add a little more timing in the lower boost area. I managed a few long boost pulls, afr are a little rich and I made some adjustments after studying the data log. I saw boost creep to 14.5 psi. I think I am going to add an electronic boost controller to try and smooth out the boost curve past 12psi. My iat are floating around 65 on a freshly iced tank under full boost low 50s in lower kpa.

arghx

iTrader: (3)

if the lowest value should be 0, but then you need to ramp in timing retard a LOT earlier with that higher compression. You are highly dependent on ambient temps and intercooler. Pull 1 degree at 40C which is 105F. Then shift the rest of the table down by 50 degrees F and ramp up the timing retard.

so try

0F - 0 degrees -- or however you set your lowest value.
105F - 1 degree
130F - 2 degree
150F - 3 degree
170F - 6 degree
190F - 9 degree

This is important which such high compression ratio and iced air/water intercooler. You are betting the store on intake temps. Once you get past 55C/130F it's not about making power, it's about keeping the engine alive.

when you say electronic boost controller, are you talking about external box (Greddy or whatever) or using the Megasquirt? I haven't used the Megasquirt 2 EBC but I have used the MS3. I don't know if they added the updated code with the closed loop "bias" table from the MS3 to the MS2.

You can run the Megasquirt as an open loop EBC if you don't want to mess with tuning the feedback gains. Many of the external controllers are pretty dumb units anyway (AEM controller is open loop only for example).

wankelbug

i am going to run the ms2 open loop since i removed my idle air valve on this round of upgrades i have the fidle wire available to operate the solenoid. again this is a drag car so it will mostly be some quick passes.

what have you experienced to be safe rpm to spin the motor to in boost? i know the power starts falling off (on a stock port engine) around 6500 but i want the opportunity to wind out 3rd in the 8th or 4th in the quarter.

arghx

iTrader: (3)

Intake port closing timing and turbine A/R are going to be your biggest factors usually. I would be surprised if your power continued past 7000 or 7500. I doubt you'd have much benefit to revving more than 8k.

N/A engines generally make power at higher rpm better because they are using the aux ports (which you have) and on later rotaries VDI and (Renesis) VFAD for pulse tuning. There isn't a turbo corking up the engine.

wankelbug

I have a vdi intake with it wired open. Only reason to rev past 8k would be either to not have to shift 4th in the 8th mile or running out 4th through the traps.

TitaniumTTRE

On my 13B-RE I'm running 9.4:1 compression rotors and my timing is set MUCH higher than that. I want to say 15-17* @ 1b. I also run it up to 25-26psi. A few times when the WG line failed she boost spiked there without aux injection either.
I PREFER to run the 9.4:1 rotors in street cars because of the characteristics they provide at low boost and transient situations and for street driving. They seem to be MUCH peppier at light throttle lower RPM's.

gxl90rx7

iTrader: (1)

im also running 9.4 rotors but in an REW, with an EFR7670 at about 12psi on 93. I have done several track weekends on this setup and nothings blown up yet lol. my timing is roughly 13-17 degrees, with 12 deg split at that boost. Ive been running it at 10.5 AFR. I have noticed it will start to knock/detonate hard, noticeable hesitation if AFR is mid-11's or leaner

TitaniumTTRE

I would be really curious as to what your AIT's and EMAP are.
The timing is very close to what I run, although I run alot leaner than .71L. Closer to .8L, somewhere around 11.7 if not a touch leaner than that and I've never had any knock or hesitation.

gxl90rx7

iTrader: (1)

i do not have emap sensor, but my AITs top out at 130F on the track with a vmount and true cold intake. EGTs are pretty high.. mid 1600's post turbo on the track. not sure how bad that is lol

but yea really enjoying the 9.4 rotors, i wont go back. i was going for optimized low and mid range with this setup, its a lot of fun to drive with lots of torque. turbo hits 10+psi at 2000rpm

TitaniumTTRE

That's..... not great for EGT's especially post turbo. What the hell turbo are you running that hits 10+ @ 2k? I suspect the EMAP is too high and that's contributing to the knock

BLUE TII

iTrader: (9)

TitaniumTTRE
That's..... not great for EGT's especially post turbo. What the hell turbo are you running that hits 10+ @ 2k? I suspect the EMAP is too high and that's contributing to the knock

He said EFR 7670.

On my EFR 7670 with HKS T04Z manifold and 1.05AR exhaust housing on a 4th gear pull data log I could only get 5psi at 2,000rpm (125ftlbs torque) and 10psi by 2,500rpm (175ftlbs torque). Oh yes- on 8.5:1 CR rotors.

The smaller diameter runners on the Turblown exhaust manifold, tighter 0.92AR IWG housing and 9.4:1 CR rotors on gxl90rx7 set-up should help low rpm spool some over mine.

TitaniumTTRE

Whoops, my bad.

That's still impressive.

They definitely will. I'm just curious as to what the underlying cause of the knock is.
What are you running for an ECU and CAS?

BLUE TII

iTrader: (9)

gxl90rx7 im also running 9.4 rotors but in an REW, with an EFR7670 at about 12psi on 93. I have done several track weekends on this setup and nothings blown up yet lol. my timing is roughly 13-17 degrees, with 12 deg split at that boost. Ive been running it at 10.5 AFR. I have noticed it will start to knock/detonate hard, noticeable hesitation if AFR is mid-11's or leaner

I'm just curious as to what the underlying cause of the knock is.
What are you running for an ECU and CAS?


gxl90rx7's 7670 is in his FD with Haltech PS1k.

lastphaseofthis

iTrader: (8)

this is great news to me, i have 9.4 in my current motor, and today i just got a 8.5 core in to build for the SXE 7670 MAXING.
gonna have a go with the 9.4 block first. and maybe swap motor if its goes... or can't hit 400hp./25 psi

jair13b

hello guys,
imm looking to turbo my 1986 6 port rx7 using an rtek ecu setup, i have been communicating with the people at rtek and they advice me to get the N332 ecu, AFM and MAP sensor all from the 87-88 turbo II. i want to run 720cc primary and secondary injectors, with the high compression i know the boost cant be too high and im fine with that, i dont want to make big numbers just a better 6 port than what was in 1986, the engine will be rebiuld to take the abuse the turbo will make.

im simply looking for some advice on how to go about it. im wondering if i need to get the turbo II engine harness to be able to communicate with the ecu.

thanks guys.

lastphaseofthis

iTrader: (8)

i will answer this very question, as i am on an rtek also, until i reach it's limits, then i have an MS3-pro.

first of all the rtek will be limited to stock boost pressure, so thats 15 psi.. can't quite max my turbo on 15. so i may try a conversion to a 3 bar with the rtek but thats hasnt been done. its a 2 to 5 v scale. most sensors are 0 to 5.
also thats not enough fuel for more then the stock turbo really. if your running the stock on a 6 port 9.4 then the rtek is a good way of reducing the timing of the fac

TitaniumTTRE

That could be the issue right there. I've proven time and time again that the Haltechs can do very odd things with their timing especially when using the stock CAS. An FFE kit and running a hall sensor could potentially make some improvements