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RX-7 2nd Gen Specific (1986-92) RX-7 1986-92 Discussion including performance modifications and technical support sections. |
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01-08-2011, 11:41 AM | #1 |
Lifetime Rotorhead
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Req. for comments & questions on my turbo upgrade plan
Hi guys, this is a follow up to my other post, reference:
http://www.rotarycarclub.com/rotary_...ad.php?t=13083 The skinny is if I decide to purchase a BNR stage 1 upgraded turbo (vs. the stock rebuild) as discussed in the ref. thread, I need to address fuel & fuel/spark management. After a little research here & elsewhere, I've drafted a plan that should support running the upgraded turbo safely and meet my goals. What I'm looking for is your critical review & comments to the plan - pros/cons, etc. I'll also pose a few associated questions along the way that I need answers to prior to executing this plan. This will be a lengthy post, but hopefully will generate information useful to anyone starting out on the FC mod/tuning adventure. My goals: I'll be more than satisfied if my car even comes close to producing the 300~320 rwhp BNR claims their stage 1 turbo upgrade is capable of. My philosophy is in line with "resto-mod" thinking. Meaning when replacing worn out parts, if you can improve upon stock performance & reliability without compromising the car’s original looks, its character or baseline reliability, then go for it! Reliability is orders of magnitude more important to me than the end HP #'s I achieve. Also, since I’m too lazy to be swapping out emissions components every time the state of MD orders me off to the sniff tester, I will retain the factory emissions components needed to pass the sniff test. Regarding schedule, I MUST have this done and fully tuned before I hit the road for DGRR-11 (28 Apr 11). My gut tells me finding a competent tuner to optimize my tune on a dyno within that short schedule is going to be my greatest obstacle! Baseline car & current mod list: Car as it sits is a nearly 100% stock ’89 turbo, faithfully restored to “like new” condition. For those of you who attended DGRR ’10, it’s the black-on-black T2 that took home 1st place in show for 2nd gens. Engine was rebuilt about 50K miles & 12 years ago, all stock internals, no porting was done to it. ECU is stock N370, with no mods, but I did install a new Mazda engine wiring harness back in 2008. Currently the stock 550cc injectors are in all 4 holes, which are periodically sent out for refurb & flow testing once every other year. Fuel pump is stock, but I did the FP rewire job some 10 years ago to ensure the FP gets the voltage & current it needs. I’ll need to check my handy work to verify if it's still up to snuff. Exhaust system is a Bonez DP out the turbo (2.5" diameter pipe), going into the stock mid-pipe & main cat, then into a Borla dual cat-back exhaust. Intake is all stock, other than a K&N panel filter installed in the stock box. Other than removal of the pre-cat, all emissions equipment is installed, works and is functional; car easily passes MD sniff test. Other mods relevant to this discussion include a Koyo radiator upgrade which will soon go in (part ordered), and WRT lubrication, I did the e-shaft thermo pellet mod. Reiterating from the referenced post, the BNR Stage 1 turbo upgrade I’m considering is basically a rebuild of all my stock S5 turbo wear parts, to include balancing. BNR replaces the stock compressor wheel with a T04b V-trim wheel, running inside the stock compressor housing which is machined to fit the new wheel. The waste gate is ported, and the turbine wheel gets some clipping to reduce back pressure. The waste gate is preset to open at 7~8 lbs. They claim this turbo is good for 300~320 rwhp with the right setup. Planned Upgrades to support the BNR Stage 1 turbo: Fuel Injectors: Replace all four FIs with 720cc injectors. From what I’ve read so far, these would provide more than enough fuel capacity to support my goals, and putting them in all 4 holes provides the tuner a bit more wiggle room to optimize drivability around the primary/secondary transition point, and throughout the power curve. Questions: (1) Is this true, or for my modest goals would my money be better spent elsewhere by running my stock 550’s in the primaries and just upgrade the secondary’s to 720cc? (2) Where can I source a set of 720cc injectors that are drop in replacements (mechanically and electrically) to the stock 550cc high impedance FIs currently in there? I really don’t want to mess with the stock fuel rails; but can handle the electrical mods to change FI harness connectors if needed. Fuel Pump: Assuming that I verify I have good voltage at my rewired stock FP, will the stock FC pump be sufficient for my modest HP goals? If not, what replacement FP do you guys recommend and why? Fuel/spark control: I’m thinking the most expedient and cost effective path for me is to send my stock N370 ECU out to DTI for the RTEK 2.x upgrade. Details of what the RTEK can do may be found here: http://www.pocketlogger.com/index.ph...age=2&ecu=S5T2 From what I’ve read, it appears the RTEK can provide enough tuning flexibility to support my modest HP targets, and it seems to mesh well with my resto-mod philosophy (i.e., no major hacking/wiring harness work, low risk to stock functionality and drivability). But I’m not 100% convinced yet – answers to the following questions might get me there: (1) Have any of you successfully used an RTEK to wring about 300 HP out of your turbo setups? If so, please share the particulars. (2) I have zero experience tuning ECUs, so out of the box, how easy or hard will it be for me to tune my RTEK modified ECU for the first time at least well enough for me to safely drive the car to a reputable tuner for optimizing on a dyno? This drive is likely to be a 3+ hour road trip, one way, assuming I can get Dave at KD Rotary to do this for me. (3) If Dave can’t do it for me, can anyone recommend a reputable tuner with RTEK & rotary experience within a reasonable drive from the northeast corner of MD? Thanks! Pete |
01-08-2011, 01:14 PM | #2 |
RCC Loves Me Not You
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The Rtek should be able to handle your goal with minimal issue. especially if you use the injector presets available within the software. For instance you can select 550/720 and it will automatically adjust the fuel to run on those injectors and achieve the stock flow, which will let you get your 3 hour road trip without issue. Tuning on the other hand is slow. you have little direct input (ie writing in the number) and must use the sliders. Beyond that data logging and other functions are easy to use. On the other hand I do not know when the built in fuel cut will start nor the max load reading on the RTek is, which may limit your HP goal, but i doubt it will be an issue.
If you were doing an NA build I'd sell you mine
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The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group |
01-08-2011, 04:20 PM | #3 | |
Lifetime Rotorhead
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01-08-2011, 04:29 PM | #4 |
RCC Loves Me Not You
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But is 1 Bar enough to reach your 300HP goal? That's the issue I'm thinking of.
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The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group |
01-08-2011, 05:07 PM | #5 |
Lifetime Rotorhead
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Don't know. The 300 rwhp figure is BNR's claim for the turbo; I don't necessarily care if I achieve that or not, but would like to go as far as I can without compromising reliability. Since I'll still be running a cat & emissions gear, I doubt I'll ever hit the 300 mark, but I'll be overjoyed if this setup hits anything above 250rwhp.
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01-09-2011, 05:42 AM | #6 | |||
RCC Addict
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I've only seen "Japan" (I think it was SARD?) that offers a larger fuel injectors that uses that oval plug. Else, if you're willing to splice in a Bosch-type (i.e. older, rectangular) plug, you open up a lot more options. Impedence isn't a problem, as you can splice in resistors to compensate for the impedence change. GReddy offers 720's that are drop in, but use the older, Bosch plugs. There are other aftermarket offerings, but most of them are crap - that's a whole nother thread in itself. Just stay away from Venom and Deatchworks... If you do replace the primaries, you run into possible cold-start issues, unless your fuel control can effectively adjusting cranking fuel delivery. (I dunno if the RTEK can do this?) Playing with the Rotary Performance fuel injector calculator: http://rx7.com/cgi-local/2ndgencalc.cgi 4 x 720's give you about 280 at the wheels. Quote:
It maybe maxes out at around 250hp at the wheels. This is why an upgrade fuel pump is highly recommended. Walbro's are the cheap standard, but be careful about fakes... Look for the "255lph" Walbros. (The stock FC turbo flows right around 180lph - 190lph.) (Do a web search on keywords "walbro fuel pump fake", and you get a lot of hits.) I like the stock JZA80 Supra TT fuel pump. It has OEM quality and reliablity - made by NipponDenso. It flows slightly more than the "255lph" Walbros. It drops in. It's priced slightly more than the Walbro at closer to $200, but I think it's worth it. Quote:
-Ted |
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01-09-2011, 08:18 AM | #7 |
Lifetime Rotorhead
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Thanks for the input Ted.
WRT the fuel pumps, are you saying both the Walbro and Supra TT pumps will mechanically drop right into the FC tank and mount up without any fabrication work? I assume I'll need to splice in an electrical connector? From a reliability standpoint, I'm thinking the Toyota pump is the better of the two. Another dumb question - is JZA80 the P/N for the pump, or is that just Toyota lingo for a Supra TT (i.e., as FC3S is for us rotorheads)? I ran into those Venom injectors while searching the net; "too good to be true" came to mind, given the cheapo prices. Thanks for the warning! Looks like the Greddy 720's with the Bosch pigtails will do the trick for me. Given what you said about potential cold start issues, I may have to reconsider putting 720's in the primaries, after I learn more about how the RTEK works. WRT the RTEK, what I gather from their website is that for fuel correction, they give you a 14x18 (252 points) RPM vs. boost table to play with, where each cell is a correction factor the user can set, in a range of +/-37% of whatever the corresponding stock map values are. I'm not exactly sure of what quantity the +/-37% refers to -- is it injector duty cycle, AFRs, or something else? More questions for the RTEK guys! |
01-09-2011, 12:18 PM | #8 | |||||||||
Test Whore - Admin
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-The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. -Angry Motherf*cker Mode ENGAGED- |
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01-10-2011, 01:37 PM | #9 | ||||||
Lifetime Rotorhead
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Best I can gather so far, Rtek simply allows you to tweak the input parameters that drive the stock ECU fuel/spark control algorithms - it doesn't do anything to change the algorithms themselves. It also allows some additional user control over certain stock ECU functions/behaviors under certian conditions (e.g., turn off overboost fuel cut, turn off AWS). |
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01-09-2011, 11:59 AM | #10 |
destroy, rebuild, repeat
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the latest rtek 2.x has cranking fuel correction i believe. the +/- 37% is for fuel correction from the stock fuel map. so if the stock map fuel injection amount was 4 ms, and you had that particular cell set for +25% correction, the final injection amount would be 5 ms (4 + 4*0.25). I think rtek 2.x would work well for your goals
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01-10-2011, 03:26 PM | #11 |
I-had-a-bad-experience...
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I got a good deal on these injectors from a member. They are 750cc, which I found adequately close to 720, especially since I can adjust fuel either way. (They look different than the picture on the website.)
http://www.rceng.com/Saturated-Injec...top-P64C6.aspx They also have these pigtails that I used for completely plug-n-play install. (tho pricey) http://www.rceng.com/Denso-Clip-Connector-P48C9.aspx
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'15 Juke Nismo '06 MX-5 GT SOLD '04 S Silver RX-8 GT Track Day Use SOLD '90 Black TII vert w/ Sprint RE stock port/turbo DD dyno (242.6whp@5500rpm @12psi 8psi@redline) and (250ftlbtq@4800rpm @13psi) SOLD '89 GTUs 6p TII SOLD, '87 sport SOLD, '79 SA stock SOLD '91 B2600i 4x4 w/ Rx-8 LSD SOLD |
01-10-2011, 05:16 PM | #12 | |||||
Test Whore - Admin
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-The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. -Angry Motherf*cker Mode ENGAGED- |
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01-11-2011, 08:25 AM | #13 | |
Lifetime Rotorhead
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http://www.rx7club.com/showthread.php?t=914287 I've PMed him to get more detailed info, such as who is doing the refurbishment, cleaning & flow test work for him, does he send flow test documentation along with them, etc. He's currently out of stock, but expects another batch within the next week. While I'm waiting for his response, what do you guys think about using refurbed, flow tested and documented Bosch injectors (assuming work is done by a REPUTABLE shop - I WILL check references!) vice brand new injectors in this project? I've been periodically sending out my stock 550's for refurb & flow testing, and my experience has been as long as I deal with a reputable shop that provides documented test results, they are an economical alternative to buying new ones. At only $215 for a set of 4x 720's, it's a real budget pleaser. Thoughts pro or con? |
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01-10-2011, 05:29 PM | #14 |
I have radioactive semen
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for what it's worth, if you're interested in the Supra pump, i used to order ALL of my Toyota repair/maintenance parts from either Newark Toyota (just to be clear, that's Newark, DE) or Conicelli Toyota. i've found their prices to be good. just tell them you want the fuel pump from a Supra Turbo (i think the JZA80 years were 1993-96) - i can honestly say that in 8 years, neither of those dealers have ever messed up an order for me. so if you have trouble getting the part number and sourcing the pump, try one of those places. i hope this is helpful.
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01-10-2011, 08:57 PM | #15 | |
Lifetime Rotorhead
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