boostantix

so here's the deal. I found an 88 GXL that has been swapped to a 5 speed S5 T2. the car has a JDM 13BT and tranny from osakajdm. S5 drive shaft, interior, electronics, ect. ect. everything S5 stock car with 2.5 inch exhaust. my question is, would the car be a bad idea to obtain as a main mode of transportation to be driven 3 times a week 75 miles all highway. because I've been told that rotarys do not like boost, period. also, the car has a creepy boost issue. all stock piping, and yet you have to regulate boost with the gas pedal. the guy claims that if you go WOT, the boost will most likely keep building until the engine blows. he states that you have to ease to 10 PSI and leave the pedal there, and that its been to 15 psi with no problems. it has no fuel cut defender, no fancy injectors, or fuel line pulse eliminator, all stock, and claims the vac. lines are ran just like factory. the engine is strong, and has great compression, but this boost issue kinda scares me, but the car is daily driven as it is, I was just wondering what all would be involved in this issue, because the only turbo vehicles I've owned and maintained are a 96 GST (DSM) and Turbo VW type 1 (built myself) Ive had N/A rexs before, but I know that there's a huge difference in a T2 vs. an N/A. I thought about just plugging all other vac. lines and just running a line straight to the wastegate actuator from the compressor housing, and apparently the factory boost controller for the car has been eliminated/bypassed, along with all emissions BS. any input would be great, I really want the car, it's a florida car, no rust anywhere on it, and the car is clean and is a well done swap/conversion, I just don't want to buy a ticking time bomb, or something that will cost an arm and a leg to fix.

RX7 13B 4 UR AZZ

Ok for one Rotary and Boost are a match made in heaven. And as far as having to regulate boost pressure with the gas pedal means something is wrong. The way the turbo system is designed it is meant to have a bypass valve for the exhaust that controls boost not the gas pedal. you need to check make sure a couple things

1. your map sensor does not seem to be working properly if the ecu is not hitting fuel cut without a fuel cut defender

2. You need to check the waste gate on the turbo it might be stuck. (check actuating rod for movement) Also if the rod moves apply compressed air to the actuator see if it moves the arm.

3. The actuator has a certain psi spring on it that will open the waste gate at a certain psi independent of everything else so running a vac line to a boost source is ideal.

4. When you free up the exhaust on a stock turbo it will boost creep because the gas flows in the path of least restriction which means the waste gate needs to be ported to control boost.

1988RedT2

To me it sounds like the guy who did the swap cut a few corners and left a few things out. If the engine is still good AND you are comfortable troubleshooting turbo systems, then the car might be a worthwhile prospect. It sounds to me like the wastegate simply isn't hooked up or isn't working.



Any swapped car has the potential to be a huge headache, since it isn't factory anymore and you didn't do the work. Kinda makes wiring and vacuum hose issues a major pain to sort out.



+1 on rotaries loving boost. I've had mine up near 20 psi, and she pulls like a monster, but I've got larger than stock secondary injectors. Boosted rotaries are happy as long as you feed them lots of FUEL. Run lean under boost and it's bye-bye motor.

RX7 13B 4 UR AZZ

+10,000 on running lean = bye bye motor LOL ask me how i know.



your best bet is to strip it down and rebuild in not the motor but everything around it. leave the keg in place with the trans but take everything else off. New gaskets on intake manifolds, new vac lines, new injector o rings and seals ect....



what you are doing bye this is allowing less room for error if you know everything is well sealed up along the intake path and everything around it has been inspected and replaced or reused in good condition then you have peace of mind. Not knowing is your worse enemy the more you know about your particular car the better off you are.



if you are diagnosing a rough idle for example you know that the intake manifold and everything in its path are tightly sealed up so it wont be a vac leak there get it.

boostantix

well, i understand the way a turbo system works, and in understand that this car still has the rats nest in it, its just all plugged off..... everything is still sealed up as it should be being that the engine was just purchased, and Ive never seen anything mediocre from osakjdmmotors.com and just running a line from boost source to wastegate would lower the boost the car has wouldn't it? for example, my T28 in my GST has a 7lb spring, but by usage of the factory boost controller, it runs 12 lbs and on REALLY cold nights it has 13. and the gentleman told me the wastegate does open, but according to him, it either flys open way to early, or stays shut too long, which makes me think that replacing the lines would cure the problem. Ive diagnosed and repaired turbo systems before, im not new to them, just the rotarys setup, because compared to a piston/cylinder engine, its different in the fact of sooooooo many more lines. i was informed that the car has seen 20lbs before on an older turbo, and nothing bad happened, and that was during the first few times of driving the car, you know, excited to drive and finding limits and what not. but the rubo on the car now is brand new, and has never been to WOT. I just dont want to get into anything that i have to tear apart every 3000 miles, my GST is supposed to be high mainence, but its not to me, i change the oil and boost leak test when i replace the oil, and ive never had a problem since i put the car back together(15000 miles ago). what is the stock amount of boost TII's should be running? and where can i find a vaccum diagram? all the emmisions have been eliminated from the car, and i know that will play a part in restoring everything else back to normal, i just want the car to be able to go WOT like it was built to do and still have plenty of pep, im supposed to see the car this sunday, and i hope its what everyone has been telling me, because word of the grapevine is that this TII should blow away my 260 HP 239 ft lb torque DSM (actual dyno numbers), and i definatly dont need something that cant get me from A to B 3 times a week.

RX7 13B 4 UR AZZ

A turbo system regardless of rotary and piston is the same. All the parts are the same exhaust manifold, turbo, waste gate internal or external, down pipe. If you have worked on turbo systems before this should not be new to you.



Just cause the motor was bought from a reputable jdm engine seller doesn't mean they resealed the motor with new gaskets orings ect... they just make sure motor has good compression and sell it.



You need to go ahead take intake manifold off remove the rats nest which only causes problems and run a line straight to the actuator till you resolve some other means to control boost. IE... a profec b or something along the lines. Do as you like running added boost on an already over worked fuel system is only going to lead to a costly repair that could have been avoided by spending a little time simplifying your engine. remember these stock are set to run at 7.5 psi and even at this level injector duty cycle is darn near maxed so have it your way.

RX7 13B 4 UR AZZ

keep going into that boost range on a stock system and you lucky to see 3K Miles.



Also a period would help every now and again helps us who read out loud breathe.

RONIN FC

If you were OK with the reliability and maintenance of a DSM, you shouldnt have problems with a rotary. Dont get me wrong, I love the DSMs. (And if I find a decent 1g TSI it may end up in my driveway) But from my experience FC Rx-7s are moderately more reliable.



The most important thing to get on these cars (any modded turbo car for that matter) is a Wideband and logger setup. DONT play with BOOST and DOWNPIPES WITHOUT IT... And like everyone said, make sure its running OK and you will be fine.

RX7 13B 4 UR AZZ

+1

boostantix

well, the car has been running like this for about 1200 miles, i finally got to see and drive the car, and it just seems like WICKED boost creep, the guy had a narrow band o2 hooked up and the car was RICH until 15 psi........ then it started leaning towards stoich (weeks ago). i know that narrowbands are nothing to belive but its something. also, he was partial to the fact that the ECU has been played with because the seal has been broken on the case. this car is far from perfect, but it did fire right up, but the idle surged for a good 2 mins until warm. after warm up it purs, but the funny part about the idle is if you turn the climate control blower motor all the way off, the car's idle will plumit and almost die, but remain alive, it only really idles well when the blower motor is on. Also, he had told me that 10psi was nothing that would hurt the car...... i wish i could speak to someone with a little more "experience" opinion. because to be honest, I never like listening to one person about something that is new to me like this..... but obviously something has to be right, the car has soo much power, it makes my DSM seem really slow lol. in the event i go back and get the car on friday, what would be the things to look for as far as problems, or particular things that might be a tell tale sign of something wrong, aside from the boost issue. such as something i can directly look for to expose issues...... i appreciate all the help from everyone, like i said, Ive had an N/A before, but is was factory and really didn't need any crazy attention, this is the first time i will have ever obtained a swapped car from someone that i don't know. but for the record, for what its worth.... when first starting the car (cold, hadn't been started before i got there today) no smoke, no anything out of the exhaust, or while driving, except for a whole 1 backfire i got in between gears due to the vented BOV. and his 68000 mile GXL (N/A)smoked on start up