LUV94RX7

I'd like to start a thread to discuss why we have so many FDs blowing up and what we can do to help eliminate the problem. I know many owners are planning on upgrading to new ECUs and some to single turbos. Many have already upgraded and some have blown their motors. Some of the blame seems to be aimed at ECUs like PFS PMC, PFC etc.



I'll start by admitting two years ago before I knew anything about FDs I blew my motor with a PFS PMC at the high(15psi) setting. It was on a stock FD. I'll take the blame as I knew nothing about what needed to be done to run properly at 15psi. This is my planned new configuration:



'94 white, pep, red leather,

mods: Street port and polished stage II, upgraded coolant seals, Hurley 3mm racing apex seals, XS T04E Turbo Kit,

GReddy SMIC, Pettit ss resonated MP, Pettit ss cat-back,

RP Racing fuel pump, Aquamist 2s water injection kit,

under pulley kit(no air pump), Pettit short shifter kit, boost gauge, AEM EMS, 3-bar MAP Sensor, Profec B(12-22psi), 1600cc injectors, LaBreck bushings, Evans coolant.

https://www.nopistons.com/luv94rx7.html



My car will be dyno-tuned by Dave at KDR in the next couple of months depending on when AEM can deliver their new ECU.



Why have these FDs been blowing up???????



What can be done to help eliminate future FDs from blowing up?????

MtnRacer

lol, I just wrote out a REALLY long and complicated response to this question, but after I read it, I just think it was too imflammatory. I'll condense it down to one line, and then let people chastise/condone/whatever me.



<climbs on top of anti-drag racing soap box>



STOP DRAGGING THESE CARS!!!!



<climbs off>



lol, wait, that was the imflammatory part of it. Oh well, before I run the risk of writing out ANOTHER long winded response, I'll just say this: The twin turbo/vaccum hose nightmare that so many FD owners are now familiar with is extremely complex, maybe even overly complex. But it DOES squeeze 255 hp out of a 1.3 liter engine. This, I believe, has to be one of the highest hp/liter ratios in the stock sports car world. Trying to squeeze ADDITIONAL hp out of an engine that is already being pretty heavily taxed is asking for trouble, I think. With that said, I think it'd be interesting to see a study of one of Japans VERY best cornering machines that haven't been modded and have had proper care their entire lives. I'm willing to bet they last a bit longer(not much though). It's a shame these fscking SUVs came along and dried up the sports import market, I think we'd all be better off if we had gotten more than 2 1/2 years of FDs. There, that feels better

vosko

i would say most FD's have blown up due to abuse. abuse meaning full exhaust and non upgraded ecu, etc. very rarely have these cars blown up for no reason....

LUV94RX7

From what I've read from different sources I think these turbo rotaries are very sensitive and when professional rotary tuners

can blow them up on dynos that is not a good sign. Maybe that's the main reason why JIM LABRECK is dumping a V8 in his FD. If mine blows up after spending well over $10,000 with the pros and all the reliability and performance mods I'll say

"I could have had a V8".



Ken

LUV94RX7

This just posted by gmonsen on the "big list".



"all the points people are making have merit. broadly, heat, stress and pressure are the enemies. the engine depends on fluids, air, and electricity carried in hoses and wires. every single system that is involved needs to be brought to the level needed to match the fundamental changes to the engine: turbo(s), porting, intake, IC,

and exhaust. i don't think enough people go far enough with all these

systems. everyone upgrades the vacuum hoses to at least silicone and in the last year and a half or so more people have upgraded the fuel pump, hoses and injectors. I think that's an absolute necessity, as is a good radiator and IC. I don't think that the "absolute" best or biggest of either is as big a deal as making sure everything else is done right as well. once all these physical system upgrades (not to imply an order necessarily) are done, the engine management system had to be upgraded. its my opnion so far that the Power FC doesn't really give you as many benefits as a Haltech, MoTec, or maybe this new one, the AEM. you do need to ABSOLUTELY set the air fuel ratio correctly using a wideband lambda meter. and, you should set it at about 11.5:1 and not the all-out 12:1+ that racers use. you really won't lose noticeable power, but you will pick up a lot of reliability (read: headroom).

you need to be equally sure your timing is right and not too advanced. and that the timing split is kept far enough away in tome so that an error in the ignition firing doesn't cause the trailing to firew a hair before the leading, thus lunching your motor. you also need to use the rest of the ems' features to improve everything. you can use the ems to turn the fans on and off and full on or half on. one fan or two.



i personally think that water injection is a very righteous way to decrease internal engine chamber temps. at $500 for an aquamist 2c splicved into an injector wire and sized to provide 8% water to fuel, it will spray volume pro rata with fuel at 8% all the way and keep the housings a lot cooler than just with an IC.



some say you don;'t need to upgrade your seals (peter rice/rice racing). i am not sure, but switched to Hurley seals a while ago. their standard seals were in my motor when it made 600+ rwhp at 30 psi for a few seconds. broke the motor down and everything was fine, except the Hurley seals had collapsed. their shape (edge) and softer material hadn't damaged the chambers or rotors. put the double spring racing seals in and haven't had a problem since. (haven't run it at 30 psi either...)



summing up, i think too many people just put on the go fast stuff. downpipe, exhaust, porting, maybe a singlke turbo and Haltech, an IC, and crank up the boost. and either smash the car up immediately or blow the motor a little while later. that's why i've always thought of a single turbo upgrade costing much more than the $7500 for the basic turbo-related stuff. a good single turbo full install is $15,000+ or you can easily blow the motor and start over. it cists $5,000+ or so just to reasonably upgrade the sequential system. if you want reliability. (blah, blah, blah)"



Ken

hapa

I agree heavily with Gordon's comments, and would like to add some of my own. The 2 major reasons FD's blow motors are:



1. Temperature, the first can be solved by simple maintanence, I'd recommend annual flushing of the coolant system. Another freebie coolant mod. is to tape up all of the small passage ways around the radiator with a good metal duct tape. This greatly enhances the cooling system of the stock radiator.



There are other mods to help the cooling of your FD. By changing your AST to a metal unit (or removing it altogether) and adding a switch to for the Fan Mod. You again help the cooling system. The biggest difference in cooling I've seen is changing the Pre-cat to a downpipe. In Japan the FD does NOT come with the pre-cat, this adds enormous amounts of heat to the engine compartment and adds many many more problems down the line. The stock Temperature gauge works like an on-off switch. When your in the H you've already overheated your motor. Add a real temperature gauge, and an aluminum radiator, and you're well on your way to being "cool". Another note of preventative maintenance is to change out the stock cooling hoses. Especially the turbo coolant hoses, throttle body coolant hoses, and your radiator hoses.



2. Tuning, is a major part of every engine. Unfortunately Rotary motors do not handle detonation as well as their piston counterparts. It's extremely important to keep track of your fuel situation. I would never add boost without adding fuel. It's important that your fuel system is up to par with your boost. So when you spend $400 on an intake, $300 on a downpipe, $15oo on an intercooler, $600 on a cat back, you definately should spend $600-$1200 on a computer, $300 on a fuel pump, and change your fuel filter, and make sure your injectors are capable of handling the boost your putting infront of them.



Most Rotary motors do NOT blow due to internal problems. I.E. you can't blame the motor for a split AST spilling coolant. Nor can you blame the motor for popping an apexi seal while boosting 15lbs on a stock fuel system with a dirty fuel filter.



Luv- I would also note that many FD's are being resold cheaper and cheaper, and the new owners do not know enough about their cars to care for them properly. After all most Mazda trained tech's don't know how to care for an FD. Also when you buy a used car with ~80k miles on it, you have NO idea of how it was cared for. Was the oil changed less than every 3k miles? Was the proper octane fuel always used? is the cooling system up to snuff? etc. etc. etc. Before doing ANYTHING to an FD, make sure it's running how Mazda intended.



eric