LUV94RX7

iTrader: (3)

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.
http://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?????

the_glass_man

iTrader: (2)

Dude, NOSS makes things blow up, like the green eclipse. I've been running 30 psi on my stock turbos using an olde apple IIgs as the ecu. Damn thing works wonders. FD's or any untuned or poor tuned car will fail (or "blow up") at some point or another from detonation, increased stress on stock internals and seals. I don't know how many people I've read about that just throw a bunch of mods on the car and leave it the way it is till its too late. The PFS Purle Motor eater, is past its prime, yeah it was pretty neat 10 years ago, but is a piggy back in every sense of the word.
The power FC on the other hand is a 16 Bit ecu that replaces the OEM ecu. The problem with the PFC is that no one and I mean no one other than XS, has the right software to program all the perimeters. Yeah its fine if you want to run stock twins, but it nice to be able to mess and fine tune (if you use a wideband, or know what the hell you are doing) everything that you motor needs to keep running healthy.
AEM looks promising, but isn't out yet. Haltech you have to hack everything up and doesn't run twins as well as some others.
Put all these together and you have some potential for major engine damage.
Now lets move onto the fact that these cars simply can not take overheating (not even once), this together with the poor OEM radiator and precat doesn't help to engine longevity either.
So what can be done to help eliminate future FD's from blowing up?
Proper care, maitnence. And Proper Tunning! ie fuel amount, etc...

Toadman

I don't see an epidemic of FD's blowing up now, do you? Maybe 'cause it's winter, but if everyone does the reliability mods and "stair-steps" the performance upgrades, there's no reason why it wouldn't be reliable and stretch the mileage. Ask the guys with 70-100k on their motors what they did to increase longevity. The Rex is a "thinking man's sports car", because of its unique engine and needed attention to detail and proper maintenance. It's not a turn-the-key plug-and-play car like *cough* other 'sports' cars. Call it eccentric, call it wierd technology, call it a pain in the a$$, but there's nothing sweeter or addicting than a rotary perfectly balanced and tuned for driving.

Lost Time

User error.

maxpesce

PLEASE PLEASE PLEASE -
NOS is a BRAND NAME - NOx is the proper abbrevation for Nitrous Oxide

j9fd3s

iTrader: (3)

fd's blow up in the springtime. they hibernate in the winter

mkie

Tim Benton

iTrader: (1)

I agree and say alot if its owner error in getting mods to fast without thinking them through....intake, dp, catback with no ecu...car to car, could be a problem...through on the IC and still no ecu and your looking at a time bomb. I had the PFS PMS and was on the big list and also the smaller PFS PMS mailing list and alot of good info was passed on, but alot of users play with the settings without knowing the consequences of what they doing, timing, fuel, vent learn boost control, etc..and the same applies to the PFC, AEM, haltec, etc. don't play with it until you know what your doing. Hell, even the maker of the PFS PMS, Doug Wallace blew up a friends engine down here in Atlanta when he was trying to tune it. Greg Lackey took it to Doug and Doug blew it up on the dyno....so even people who know what they are doing can make a mistake, imagine a new user playing with the keypad because their friend is in the car and a firebird is revving its engine at him at a redlight....turn it on high JEB and I'll blow his drawers off (in a country slag accent).

Tim Benton

Johnny

It's been cold outside...maybe that's why

RecKleSs

Very well put. Most engines fail, because of the owners knowledge about the RX-7. They tend to do some mods without doing the proper steps in increasing the hp out of the car. As for the PFC, it is an extremely good ECU. I have done a few compression test and everything looks great. I have been using it for over one year and I'm completely satisfied. The owners have to do some research before installing some mods to their FD.

gregheberle

I have 76K on my original engine and I run it hard at autocrosses and track events. The reason I still have that original engine is I have only done suspension and safety mods. Powerwise it is completely stock beside a downpipe and exhaust which really doesn't give you much hp increase at all.

I've found that after 4 years I have more power stock than I have driving abilities.

Add power engine go boom.

DavidZ

The cold weather did me in. Although i thought i was safe with just a DP and catback on the stock ECU, the cold weather was like an extra mod i guess.

atihun

I have 94K on my car and yes, doing the modifications in a reasonable order and tuning is the key.

I run my car at 13 psi on the turbos. This is a stock engine and stock turbos.

My older 93 had 98K on it before some lady totaled it.

LUV94RX7

iTrader: (3)

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

vosko

iTrader: (4)

my engine in my car failed at ~87k miles on the original engine. coolant and oil seals failed. compression was still in the green

atihun

Did this happen out of the blue? Or were there indications / reasons as to why those failed? Ie. possible overheat, too much boost, no upgrades, etc?

Basically did this just happen or was there something that led up to it.

Thanks.

Ned M

iTrader: (6)

I noted they drove it home from the race anyway! That must have been after a consult with the directors of "Driven."

artguy

heat...heat...heat....that has been my problem all along....The radiator upgrade and intercooler are musts...simple as that. Had I done that in the first place I wouldnt have a car in the shop and two motors in the junk pile....it comes down to having to learn the hard way...get greedy with power early and youll pay for that mistake...

do the mods in the right order....dont skimp on parts EVER...ditch the stock turbos as soon as they cook...dont waste time and money rebuilding junk...save the dough...do it right...listen to your car like a doctor with a stethascope (I forgot who coined that here on the forums)...and things will be AOK as long as you fix it as soon as a problem arises and dont go driving around with that damn red overheat light on.

the other problem as mentioned is fuel...lack of it....get a good set of injectors and an ecu as well...and a good fuel pump.

as soon as my motor is finished and broken in Im doing the cooling system...Im not risking another motor on the inadequite stock system.

j

Solar7

There are several issues that have not been addressed here:

A. PowerFC can be properly tuned other than XS. I can tune/see/alter any function they can in my PowerFC. (I am a DataLogIt beta tester).

B. There are isses with extreme-power rotary motors that have NOTHING to do with tuning, mythical dieties, or fluid dynamics. Apply enough power/torque to any motor and it will begin to twist, warp, and move. When considering the clearances involved in a properly assembled motor, consider this: eccentric shafts are known to give up .001" at high revs. Add another .001 for the engine twisting and there goes your clearances. Now add some heat (things expand), add a little bearing wear, something is gonna give..it's usually the seals.

Serious race motors utilize a metal plate bolted to the bottom of the motor to prevent it from twisting as much, ceramic seals (that are relatively uneffected by heat...ie. do not expand). So, let's see: metal plate appx. $300, dry sump system (no more oil pan with metal plate) $4000, ceramic seals appx $3000. So, appx. $7300 will get you better durability.

Saying all this...I think it is fair to say: Our beloved rotary motors are AWESOME considering the thrill/displacement factor. However, expecting twice the power it was designed to tolerate has a penalty. If you wanna squeeze every last bit of power you can possibly manage, tune it on the hairy edge then expect to rebuild or freshen it more often than 100K miles. My prior motor lasted almost exactly one year...HOWEVER, I was not bummed at all since I had 40+ *hard* track days on it. High revs, high heat, high expectations. It performed great...ran with a class of cars 10x it's price and did so cheerfully. I would (actually did) do it again.

Happy rotoring!

nrolfes1

I don't think the most basic tuning/preventative maintenance tool has been brought up yet...gauges. Invest in a solid temp, boost, and fuel pressure gauge. Gussy it up with oil pressure, oil temp, exhaust, a/f meter gauges if you'd like as well. If you are monitoring and understanding your gauges from the get-go, as you make mods you can understand what they are doing to your car's health. Your car can't overheat if you are watching the gauge and take preventative measures beforehand.

ek9220ps

iTrader: (4)

My first motor blew at around 50,000 mi no mod done to the car at all, i had a turbo timer, it was eating up coolant. The 2nd time @ 68,000 mi, it was my mistake, i was running a apex pfc w/ hks ti exhaust without having it tune.

vosko

iTrader: (4)

i bought the car in this condition. the previous owner *buttoned it up* enough for it not to do that when i test drove it. it was a buy now or someone else will situation so i couldn't bring the car to have it checked out by a shop. i think the car was overheated or maybe a coolant seal just gave out due to age 7years 87k miles. the car had barely any problems from the records he gave me. the owner had basic boltons, dp,smic,catback,msd 6a, ecu,etc and ran it down the drag strip quite a few times *he cleverly forgot to tell me about that* car is still in the shop currently

bladz311

iTrader: (1)

I think I just blew a seal yesterday. I have no idea why, because I think I did the upgrades right. I installed an Apex-i power fc, apex-i cat back, hks downpipe, apex-i dual intake. I still didn't put my underdrive pulley kit on yet or my avc-r. The car's engine and turbos only have 35k miles on them. I had it up too 110mph yesterday, when I think I got some fuel cut . Ever since then, I've lost a lot of power and it idles very rough. I left the boost turned down on the power fc. The only setting I changed was the idle setting, because it came too low (my car kept trying to stall when stopped because of the 700 rpm setting). Be careful with FD's. I learned my lesson, next time I'll have it tuned properly by a pro after I get my new seals.

vosko

iTrader: (4)

i would go over your vacuum hoses first then get a compression test. just cause you were doing 110mph doesn't mean your engine's going to pop. i had my aforementioned car up to 135 with blown engine etc

bladz311

iTrader: (1)

I checked the vacume hoses, but didn't see any that were detached. I had the car up too 150 before I did any of the mods. It took it without a problem. How much would it cost to get fixed if it were my seals, because I'm sick of driving the mini van around .

vosko

iTrader: (4)

if you blew the engine it depends what you want done but generally 4-5k . just have the car checked out before you go nuts. if you do a compression test that will give you a definite answer without any shadow of doubt. that could be good or bad