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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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Old 03-05-2011, 10:58 PM   #1
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Default Turbo upgrade project is almost done

Hey guys, just thought I'd share the status of my project. Back in early January, I posted a bunch of questions asking for advice when I was still in the planning stage, see reference link.

http://www.rotarycarclub.com/rotary_...ad.php?t=13101

The project is just about done now, the car is running quite well and the only thing left to do is drop in the new Surpa fuel pump, and head up to see Dave at KD/Speed1 this coming Friday to have him fine tune my RTEK on the dyno. So here's a summary of where I'm at and how it has turned out so far....

- Yanked out my engine to get easier access to the turbo and take care of fixing a few other items that are just easier that way (leaky oil pan gasket)

- Shipped the tired stock turbo out to BNR do a stage 1 rebuild & upgrade of my stock S5 turbo, see attached pics. Bryan did a great job of it, and I'm loving the new found boost.

- Sourced a set of 4 Bosch 720cc fuel injectors for pri/sec holes, replacing my stock 550's.

- Sent out my stock ECU for the Rtek7 v2.x upgrade, and did the initial setup.

- Picked up a Koyo N-flow AL radiator to upgrade the cooling.

- Ordered the previously mentioned Supra TT fuel pump, which is supposed to arrive by Tuesday. If I don't have time to drop it in before my tuning date at Dave's Friday, I'll have him do it for me. I hate working with fuel tanks anyway.

- While I was in there, I found that some of my OMP injectors were questionable, per the FSM test, so I replaced them all with new Mazda parts. Also needed new motor mounts, and replaced a bunch of those small & inaccessable coolant hoses.

Ran into a couple of minor pitfalls along the way (what project doesn't ), but nothing too difficult to deal with...

- Needed to trim one lower corner of the stock fan shroud (I still have the stock fan) to get it to fit right. Related to this, the stock air filter cold air snorkel can't be made to fit with the Koyo radiator installed due to interference with the filler neck. I tried trimming the snorkel with the dremel, but I can't get there from here.

- The Bosch FI's were difficult to seal to my primary rails; this was solved by sourcing slightly different size fuel compatible O-rings. I suspect they came with the wrong rings (SAE vs. metric).

- Also "while in there", I noticed my brake MC was leaking and had to replace it. Related to this, the fluid stripped some paint and I repaired the damage with POR-15. Good stuff, see this post for ref. http://www.rotarycarclub.com/rotary_...ad.php?t=13214

I'll let you know how it goes after Dave tunes it Friday.
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Old 03-16-2011, 06:06 PM   #2
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Well guys, the tuning session with Dave B. at Speed1 was done last Friday, car set up per previous post. On the first dyno pull, my boost was very inconsistent - curve looked like white noise, and Dave quickly determined that the restrictor "pill" that was supposed to be in the vacuum line leading to my MAP sensor was missing. He replaced the pill with a spare he had and it was off to tuning. End result was 209 rwhp @ 6500 RPM, 188 ft-lbs torque @ 5200 RPM.

I was expecting a little bit more, but it turns out my setup with the stock ECU boost controls was maxing out at only 5.5 lbs of boost, so in that respect, these numbers are pretty good. It should have been boosting in the 7~8psi range. Dave believes that my stock main cat, which still works great from an emissions perspective, is a bit too restrictive and the backpressure is cracking open my wastegate, limiting me to 5~6 psi boost. The other thing limiting my HP/torque was my heat soaking stock TMIC -- after 1~2 pulls, we were seeing intake air temps soar over 150*F. Moving on the open road, that would be less of an issue. Anyway, this is good enough for now, at least until I get through my next scheduled trip to the MD emissions sniffer test in June....

At that point, the plan is to find a good presilencer/DP combo to swap out the main cat with and go back to Dave's to extract more ponies out of this thing. With that in mind, does anyone have recommendations for a good presilencer? Preferably one that is a one-for-one direct replacement for the main cat? I'm currently running the RP/Bonez downpipe, into the stock "mid" pipe, so it would be nice to save some cash by reusing those parts if possible. Would be easy to have an exhaust shop fabricate a straight-thru pipe for me, but I suspect the result might be loud & drone on the highway.
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Old 03-17-2011, 06:48 AM   #3
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The Racing Beat Pre-Silencer is a direct replacement for the main cat, and I highly recommend it!
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Old 03-17-2011, 07:27 AM   #4
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Racing beat recommended here. I have the full racing beat on my 89 and its awesome in comparison to the two different custom exhausts on my 10th AE.
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Old 03-17-2011, 08:40 AM   #5
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Quote:
Originally Posted by djmtsu View Post
The Racing Beat Pre-Silencer is a direct replacement for the main cat, and I highly recommend it!
Is this the same one as sold on the Mazdatrix site, reference this page:

http://www.mazdatrix.com/r-extii.htm

Part #16406 near the bottom of the page?
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Old 03-17-2011, 08:41 AM   #6
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When you head back to Daves, post up with a date... I might be able to head out there. I know I'll be out there on 4/16 for a tranny swap and a dyno assuming the tranny swap goes smoothly.

Good numbers for sure especially at tht boost level.

Feel free to add to the good guy KDR/Speed1 thread

Magnaflow makes a cat, I welded that up to some piping and some v-bands so it could be easily swapped back and forth.
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Old 03-17-2011, 09:15 AM   #7
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i had that same problem with teh BNR stage 3, you can try running an extra spring from the WG actuator to the flapper to help keep it closed. I dont think the cat is causing it to open though, stock turbine is just really restrictive

you should be fine with the stock tmic, ive never seen it get above 150F on the street, and thats running 15 psi on a p-trim hybrid
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Old 03-17-2011, 09:47 AM   #8
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Quote:
Originally Posted by TitaniumTT View Post
When you head back to Daves, post up with a date... I might be able to head out there. I know I'll be out there on 4/16 for a tranny swap and a dyno assuming the tranny swap goes smoothly..
The earliest I'll get back to Dave's will be this summer, after my next MD emissions test gets done. As easy as it is, I have little time to do the emissions swap over twice. See you at DGRR-XI.

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Good numbers for sure especially at tht boost level..
Yup, that's what Dave & I thought. With the 720cc injectors in all 4 holes and the supra fuel pump, Dave's tuning of my Rtek was pretty much all in the lean direction to hit his AFR targets, meaning there's lots of room for improvement once the boost can be cranked up. I'm starting to think it would be worth it to get an add-on boost controller to push a little bit beyond the stock 7~8psi levels, maybe up to 10 psi. At that level, I'm thinking the stock TMIC will be my limiting factor.

Quote:
Originally Posted by TitaniumTT View Post
Feel free to add to the good guy KDR/Speed1 thread .
Will do, Dave's stellar reputation certainly doesn't need it, but IMHO there isn't a better tuner/rotary guru in the community.

Quote:
Originally Posted by TitaniumTT View Post
Magnaflow makes a cat, I welded that up to some piping and some v-bands so it could be easily swapped back and forth.
Given I only have to deal with emissions testing every other year, I won't bother with an aftermarket cat. I'll just do the pre-silencer/Mazda cat swap over for the sniff test. The stock Mazda unit I've got may be too restrictive, but it still works well as an emissions device. Dave says I'd pass the testing with flying colors.
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Old 03-17-2011, 10:27 AM   #9
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Quote:
Originally Posted by 88turboii View Post
i had that same problem with teh BNR stage 3, you can try running an extra spring from the WG actuator to the flapper to help keep it closed. I dont think the cat is causing it to open though, stock turbine is just really restrictive
I forget, is the BNR stage 3 wastegate the same as what he does for the stage 1? For the stage 1, (S5 turbo), he ports the wastegate some, and the wastegate actuators are pre-set to open the gate at 7~8 psi, assuming no boost controller is intervening to make the opening delay till you hit higher boost pressures. He also clips the stock turbine wheel some to reduce backpressure, so I doubt that the turbine wheel is the issue in my case.

Unless something wonky is going on with the stock ECU/boost control solenoid and its plumbing, I think Dave's theory that cat backpressure is causing the WG to flutter open is pretty sound. That plus the fact that the wastegate is ported would really limit boost. I might try bypassing the stock boost control solenoid and run the boost pressure sensing line direct to the wastegate actuator, and see if that gets me to the 7~8 psi BNR sets the wastegate actuator to operate at.

Last edited by Pete_89T2; 03-17-2011 at 10:31 AM..
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