1989 RX-7 GTU (s5 n/a)

Sup? So i just lowered my car, next step i want to do some engine work. ive read that when working with these cars, first step before being concerned with adding horsepower, is to work on your fuel assessories and such.

so with that said, i know i have to get a SAFC-II with a narrowband (because i am n/a not turbo) and what is my next step? should i upgrade my fuel injectors? what kind of spark plugs are good for FC's? (any kind, or are there rotary specific spark plugs), spark plug wires, a good synthetic oil (castrol GTX? or Royal Purple or something like that). and change oil filter during oil change.

I dont really want to mess with the intake yet because i want to make a nice legit cold air box out of heat resistant materials and seal it off nice so when the hood is shut no heat from the engine is being sucked in the intake. ill then replace the rubber intake with a non aluminum piping (because i have heard thin aluminum piping is bad when it comes to heat resistance) and probably wrap the intake and headers.

A question about exhaust: currently my catback setup is stock but in great shape, so i dont really feel the need to replace that, but if i switch my stock header's and downpipe with aftermarket parts, is there any way to connect them to the stock cat. for example, if the downpipe is 2.5" in diameter, and the stock cat inlet is 2" or 2.25", is there a way to make them fit without replacing the cat, which will then probably lead me to swapping the catback to make it all fit right?

also after doing these things should i reset the ecu? (if i do, how?) i dont think id need to swap it because these applications wont add a significant amount of power.

any suggestions or help will be greatly appreciated. and please no flaming for the noob questions i gota learn someway or another.

again i have a 1989 rx-7 GTU (s5 n/a)


~Mike.

 

First power mods on an n/a should probably be full exhaust (header or precat replacement downpipe, with high flow cat/presilencer and new catback). You're right that you need to do the intake properly or you will only lose power.

I think the Racing Beat precat replacement pipe will bolt to the stock cat... check their website. You are losing power by keeping the stock cat and catback man. Racing Beat makes a good system that doesn't look or sound obnoxious.

As far as the ECU goes, you can gain power by leaning an n/a out. You do not need fuel injectors. So buy an SAFC and take it to a dyno to get tuned, or you can road tune it if you have a wideband (I recommend AEM UEGO wideband controller/gauge, it's less than $300 and very easy to install). You can't tune an n/a effectively with a narrowband o2.

 

as far as the fuel system, i would not mod it, leave it how it is and just get your injectors cleaned.

Oil. I think by far the most popular is castrol gtx (NON-synthetic). And since you live in VA i would slap some 10w-40 or 20w-50 in there. Temp depending of course.

Spark plugs: the standard are NGK's part numbers are BUR9EQ and BUR7EQ, you will need 2 of each. You can find them at any parts store.

My suggestion to you is not mod in favor of power, because you can only get so much out of a N/A before you have to take the motor apart. But instead to mod in favor of handling. You said you had the car lowered? Coilovers? or did you chop the springs? Look into suspension bushings and sway/strut bars. Also get some nice tires, and maybe some rims....if you got the extra money.

Remember these are only my opinions on how I would mod a N/A if I had one. So do as you please and have fun with it.

 

Get a good exhaust, tune it, then get a lightweight flywheel.

Look into getting a megasquirt ecu. You can tune it alot better than you ever could with a safc, and you can get rid of the stupid AFM! Even with a rough tune my car feels better on the megasquirt. Also, you can use it later if you go turbo.

 

thanks bro. i gota keep in my cat tho, emissions reasons. and as of right now i dont have access to a lift whenever to be able to put my cat back in before emissions. and i was wondering why is it i cant tune an n/a effectivley with a noarrowband 02?

ive heard of people running turboII injectors as secondaries on a NA (550cc i think) and tune everything properly with an safc, <- is this not a good way to go?

What are the benefits from running aftermarket spark plugs, instead of the standard NGK. for instance - ive seen some new spark plugs out that are lazer finished rod for a fine excelent spark or something like that. can fc's run any spark plug? or just the standard ngk one they come with.

yea my car's lowered, KYB AGX 8way Adjustable Struts, wrapped in Eibach Prokit Lowering springs, i may get sway bars, and i need strut bars. course i can make my car handle fine, but i still need power. Hopefully shooting for 165hp or more.

thanks for the input guys, anybody else have any suggestions?

 

megasquirt ecu? do you have any links showing some pictures and features of the megasquirt ecu? maybe some advantages to disadvantages. thanks bro!

anybody have any more suggestions for me?

~ Mike

 

Look, take it from me because I'm honestly putting down more power than most n/a people here.

For power , you could do RB downpipe, Bonez Hi flow cat, RB catback. There are also lighter systems out there too like corksport. You do not need a standalone like a Microtech or a Megasquirt. You would need a wideband anyway for that, and that is going to make passing emissions harder before it makes it easier. A standalone is not going to control your emissions equipment like the stock ECU can and it's going to take a big investment of time for tuning before you see good gains under WOT as well as streetable driving. It should not be one of your first mods, especially for a street car like what you're doing.

You can't tune a car with a narrowband effectively because it is not accurate under WOT, only cruising in the 14-15:1 range. Dynos are equipped with a wideband. Get your car tuned there.

Spark plugs besides the NGK ones everybody uses will do you no good on an n/a application. You may consider an MSD 6A box to improve your ignition and gas mileage (primarily b/c your stock ignition is old and new coilpacks are expensive), but that might give you a couple.

Do a full exhaust, custom intake, SAFC, and a tune. That will set you back nearly a grand, and then maybe you can get some more handling upgrades. After that gaining more power is going to require a lot more work.

 

[QUOTE=fc.fanatic]thanks bro. i gota keep in my cat tho, emissions reasons. and as of right now i dont have access to a lift whenever to be able to put my cat back in before emissions.[QUOTE]

Bonez makes a high-flow cat that you can use to replace the restrictive stock cat. Rotary Performance sells it with a RB header for something like $450. Pick up the RB (or whatever) catback and you shouldn't have to mess with the system come emissions time.

http://www.rx7.com/store/rx7/fcexhaust.html#Nonturbo

As far as the injectors, I read that the stock injectors are good for 200-250HP on an N/A. Anyone confirm or deny? Probably don't need to replace them but definitely get them cleaned up.

I'm no expert on this stuff but I have picked up quite a chunk of info from just lurking around and reading all the tips people put up from their experience. Try a quick search if you haven't and I'm sure you can find something useful.

 

dont' n/a's make 160 stock?

 

Well fc.fanatic, sounds like your on the right track. Heres what I would do, first all maintance issues, start with fresh plugs, wires, fuel filter and O2 sensor, check your ignition timing. Next replace your vacuum hoses and inspect your fuel pulsation damper. There are tons of threads on the pulsation damper (pd or fpd in short form). Check your tps sensors (again search and you will find out how) and make sure they are in spec. Inspect your mounts (motor, tranny, differential) as they are all prone to aging and you may not find out they need replacing until you try to put some new-found power down. Check your compression to be sure the motor is upto par. As for oil changes, skip the synthetic, just use a quality 10w40 or thicker standard oil. You may want to change out your transmission and rear differential oils also. On to the fun stuff, obviously a quality intake system is a must, and like everyone else has stated, the exhaust system is going to me more crucial than the intake. An SAFC and wideband are great additions after the routine maintance and basic bolt ons are done. Then, like already suggested, flywheel and clutch combos will liven it up. Unfortunately there is where you will begin to run out of power/driveability mods without a rebuild and some internal work. Hope i didnt go too into detail, sometimes it takes someone else to remind you of the stupid things you may have overlooked in the quest for fast.

 

thhis is simply put the best advice you could get about HP gains on a N/A. I would worry about exhaust issues before anything else. Then upgrade things lke injectors and safc etc. How many miles on on the motor as of yet? YOu dont wanna go trying to squeeze all this HP on a old motor and suddenly it will pop, but again, arghx's opinion is very concise and you should really take his advice.

 

s5 n/a's do make 160 to the flywheel, so configuring after that your probably in the 140 range on a good motor that is stock. I have seen N/A's push 250 with mods and thast to the wheels. But remember this takes serious mods and a hefty price along with it.

 

thanks guys, im glad to hear they make high flow cats, so i can remain emissions legal. now i just gota save alot up. and yea my engine was rebuilt, has 55k on it.

` mike.

 

search for DTSS... if you haven't felt something funky going on in your rear-suspension yet you haven't been pushing the car enough. Most of us choose to disable it.

 

The ability to remove the AFM alone is worth the change to standalone, do you have any idea how restrictive even the S5 AFM is? At first I didnt belive, then I tried it . . .

The ability to move fuel around is not enough, for a true tune, especially once you start freeing things up, you have to set the timing as well, and an SAFC alone cannot do that, you need a standalone.

Passing emissions with a MegaSquirt isnt that hard, the key is having your airpump in place and making sure you have a good cat. And by good, I dont just mean "New;" a lot of aftermarket cats suck.

I will agree somewhat with this general order of engine improvement0:

1) Exhaust of your preference
2) Intake (Not just CAI, but a full intake)
3) Standalone
4) Ignition box

Also, I'll reccomend the CraneCams Hi-6 over the MSD 6A any day of the week.

 

I have done a lot of reading since I bought a n/a FC a little while ago. All of the reliable sites agree that significant power gains come from upgrading the exhaust. Racing Beat claims 5-7 HP (by dyno) from their catback exhaust, and I think the gains from an improved cat are somewhere around 10, minimum. I plan on upgrading to these as soon as I have taken care of all the reliability stuff.

 

The CraneCams retards the timing for rev limit as opposed by the MSD fuel cut right? I know we bitch about that at work all the time because cutting fuel on a 800 hp engine spinning 9 grand (piston engine) = bomb.