canonize-ryda

im deciding on a t2 swap(fumbling prices around) and i am wondering what are some of the options other than porting and changing rotors, that i can do to my s4 13b na engine, like what ecu upgrades would help and such, does a alum radiator help much, i already have everything but headers for exhuast and i have custom intake, other than that can you give me some pointers? trying to get the most bang for my buck. anyways thanks

Pele

iTrader: (28)

Exhaust is probably the first thing that you shoulda done.

The factory manifold is a solid brick of cast iron... It's gotta weigh 40 or 50 lbs.
The 20-25 year old catalytic converters are probably clogged with crap.

Breathing is key to opening up the N/A engine.

canonize-ryda

my exhuast is straight threw flow besides the headers, i have no cat, and i have custom intake as well, new plugs with 10.2mm wires i have decided to get a new aluminum radiator, dual 10 inch efans, and pacetter headers, but thats all i got for now. im looking for a cheap chip for ecu or do i just get the ecu remapped after all my mods are on? how do i go about the fuel mapping for best spark and all? thats what i wanna know... i will port the engine when i can rebuild it but as of now i dont wanna pull it apart unless i have too.

TheAbsence

iTrader: (19)

Have you done your homework on determining which headers are right for you?

lonetlan

Rotary engines are a unique concept to grasp in the quest for power. But, beware of the upcoming installments you have planned. Your header/exhaust combo is debateable. Try to do some research of this matter. As many experienced engine builders prefer this method of power production over stock: Exhaust, Intake, Compression, and Power.

A free flowing exhaust is what everyone looks for, as you may know already, this brings the noise. The header is almost a never ending quest of perfection, but what matters is where you see perfection on the spectrum of power; high end power or low end torque? This is why there isn't a one header, and why pacesetter makes a debateable product.

Some would like you to explain on your "custom intake", because just changing to a cone filter and neglecting any needed duct work will "feel" like a good idea, but it isn't. You want cold air effeciently, and by converting from a stock fan to E-fan, you may have enough room to take cold air passing through the radiator and fans. If you can't, make something to block the filter from getting hot air off the engine. The stock system is pretty good for a daily driven FC(this is also debateable); I don't know what you do with your ride.

The stock FC coils are impressive, so there is no need to look at this for N/A. Some people will make a "deal" out of this, go with what you feel.

Choosing an ECU for a modified RX-7 can be a difficult decision. For your sake, you will need to figure out what your doing in the future with this. But, if you are willing to stay N/A, Rtek is a great beginner product. You ship out your ECU, and when it comes back, it is tuneable with the aid of a PDA; don't worry, its stock tuned until you mess with it, and its plug and play. When you feel the need for more "tuneability", get a full standalone system, these allow you do almost anything to get every drop of power from the 13B. Either way, you will have to teach yourself on how to tune your air/fuel ratio and timing, because people can "ballpark it", but you will have to narrow it down yourself; no engine is the same.

Research is key. Know your enemy before you attack it.

Than again... I have been wrong before... sorta?

Hazard15301

iTrader: (5)

This is actually hurting performance. Your 5/6 ports most likely do not work due to having a straight pipe. They open at ~3800k RPMs, and if they do not work, you are not getting anywhere near your N/As HP potential.


If by "custom intake", you mean a cone filter, then this as well is hurting your performance. The stock air box is more than adequate for stock to lightly modded N/As. All that is doing is pulling hot air into the engine.


**edit

Oh.... ok.... that's very custom indeed. I see the point but it needs work.


Food for thought here: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/my-custom-air-box-937217/


That is serious overkill, not to mention a huge draw on the alternator. Look up the Taurus fan swap if you really want to do that. A Koyo aluminum radiator is a good step though.


Cheap, cheap, cheap. All noise, minimum power gains.



As for all that ECU chipping, fuel map stuff... It's an N/A. You aren't going to get much out of it without either swapping on a turbo or porting it. Worrying about those things is kinda pointless. The gains, if any, will not come close to outweighing the price and effort it will take.

**edit

Eh.. lonetlan must have been typing at the same time. Pretty much the same response though.

sharingan 19

iTrader: (16)

The most notable performance gain I've seen on an S4 n/a was from swapping to an S5 intake manifold, its a much better design, and pretty much increases power everywhere.

As far as the fans go...the taurus fan isn't exactly easy on amps. The mecury villager/nissan quest fan is better than the taurus (in terms of amp draw). And the two 10inch fans I have now (had to switch for v-mount) draw fewer amps than the quest fan...

canonize-ryda

okay, i have maxima efan sitting around and may consider dropping it in, maybe some better priced headers will be better? sound isnt as issure with me since i dont care and there aint no sound laws or emission laws, and in your guys opinion should i get my ecu chipped? is it worth it just for exhuast, intake, and if i can get a s5 intake manifold then what power gains would this show? i plan on porting the engine after it needs a rebuild but for now it is a brand new crate engine with under 10k so imma wait as to not waste money to put it back together.also thought id add this i have a air pump with a msd rpm activated switch to turn on the pump to the actuators, they open at about 4k

sharingan 19

iTrader: (16)

The S5 swap (properly executed) will yield more usable power than a chip on a non-ported motor. Any header that flows more than stock (read: ANYTHING) will increase performance. A little research might reveal which header will provide the maximum stock--port performance.

canonize-ryda

so id assume i would want my ecu chipped after porting?does this s5 intake mani bolt right on? will a radiator help at all?

RotaryRocket88

iTrader: (7)

Switching to an S5 manifold isn't that hard, but it's definitely not a bolt on affair. You'll need a grinder, and some quality time with the S4 and S5 vacuum diagrams to re-route everything. If you go that route, I have a hybrid vacuum diagram I made when I did this conversion. I'll post it up when I'm home later today. Net gains end up being around 10hp, and a tiny bit more torque in the mid range.

http://homepage.mac.com/carldavis/intake.html

canonize-ryda

o then this would be worth looking into then and all i would need is a s5 uim? so with the uim conversion and headers i would be looking at say 15-20 gain? anything else worth looking into?

misterstyx69

iTrader: (142)

..one word.
RTEK.

Spirit-RE

iTrader: (25)

save for a turbo swap. Can only do so much to a n/a, and in the end, a stock port n/a is still disappointingly slow.

RotaryRocket88

iTrader: (7)

You need the S5 UIM and S5 primary and secondary fuel rails. The metal hardlines from the S5 UIM don't hurt either. The UIM has to be modified to match the bolt patter of the S4 LIM, which means drilling 1 new hole and grinding a runner to allow you to thread a nut on. The S4 TB is swapped on, the block is ground down to allow the S5 UIM to seat properly, some of the emissions solenoids have to move, the OMP rod has to be bent to clear the wider UIM and a custom bracket has to be made to attach to the driver-side of the new UIM. Oh, and the EGR has to be removed and blocked off. S5s didn't have EGRs.

Still with me? Here's a pic showing the hole drilled in my UIM, the vacuum routing diagram I made, and a dyno chart posted by an old member that did this conversion.

canonize-ryda

how much would one of these be? with all the goodies, and wow that looks amazingly clean... nice work since i assue you cleaned it. and is torque way lower? and hp and beginning.. why is this, wouldnt it be better? and rotary rocket would u go with rtek? or is it worth it for a na?

RotaryRocket88

iTrader: (7)

I think I bought everything for about $100, and then another $50 on an RPM switch to control the VDI.

Yes, I cleaned it with brake cleaner and a wire brush before painting it with some high-temp engine enamel.

For the graphs, the little differences in the two lines are probably just fluctuations you'd see between runs. A better comparison would have 3+ runs with each setup to get an average. The S5 intake manifold was designed to be both shorter and longer (thanks to VDI) than the S4, which meant a broader torque band. If anything, it should gain a bit in the mid-range.

If you don't intend to keep the car NA, you may be better off just finding a cheap SAFC. Get a wideband and you can do some basic fuel tuning that may lead to some small gains. But you won't be able to adjust timing or datalog like you could the the Rtek or a standalone.

oakback

My favorite mods with bang for the buck were exhaust, good tires, and lightweight flywheel (not necessarily in that order). Next up would be suspension, but nothing fancy, just better than stock is all that's needed for a fun car.

rx7racerca

iTrader: (1)

A rad is just a supporting mod - the stock rad has plenty of cooling capacity for any power level an NA is going to achieve, and is not bad for moderate power gains in a turbo even (iirc, the same rad was used in NA and turbos) That's if it's in good shape, which after 25 years it very well may not be. If nothing else, the plastic tanks can deteriorate and lead to a major failure.

Rtek is relatively cheap and plug and play; using an old Palm to tune it is kind of lame, but supposedly with a decent tune, taking out some of the pig richness of the stock na, you can actually gain 10+% or so. Downside is limited versatility - if you get an Rtek for an NA, you won't be able to use it on a turbo swap later. I'm considering an Rtek, in large part because it does allow some tuning, but would fit the class rules for SCCA Street Prepared or Street Touring, whereas a standalone would not.

A full standalone could be used on your NA now, and on a turbo swap later, and would allow you to ditch the stock AFM - not a major advantage on a NA, but more so on turbos when you start seeking significant power gains.

canonize-ryda

well im sorta plannin on keeping this car na and just buying a complete turbo 2 later down the road, just work on this one so i have a little summer fun, i just got my license back like the last month of summer and havent got to do much cruising in it, and btw how long should a stock clutch get me? i wanted to get a hd clutch but they were out when i got mine.

driftxsequence

iTrader: (8)

RotaryRocket88

It seems like a majority of the problem with the S5 UIM swap is the emissions equipment. How easy is it if all of that has been removed?

I looked at it and i see it as being changing LIM, UIM, DC, moving BAC valve, and adjusting the the OMP. would it be THAT simple???

RotaryRocket88

iTrader: (7)

I wouldn't say keeping the emissions equipment is that big of a problem. I already did the leg work and drew up that diagram above that shows exactly what to connect where.

Grinding the rear iron down enough was the biggest pain in the ***. It makes a big mess all over the top of the engine, so I ended up masking most of the bay off. And then I thought I had ground enough down, but the UIM just barely hit, which caused a large vacuum leak.

A close second would be bending the OMP rod to fit. It's a really tight fit behind the alternator, so it can be hard to get the shape just right. If it's bent wrong, it will hit the UIM or alternator. I also ended up cutting the large nut down for the pivot bolt on the alternator. It stuck out a little too far, so I bought myself an extra ~1/8" of clearance with a hack saw.

driftxsequence

iTrader: (8)

Gotcha,

Guess I should have clarified. My car has the emissions all removed.

This seems like a good project to get all of the parts before hand and do as much prep-work to then install in a few hours.

How did you verify that the OMP rod was the right length? I mean how do you know when you pulled the throttle the cable was moving enough?

canonize-ryda

do u need the lim as well as the upper?

RotaryRocket88

iTrader: (7)

Yeah, I read that you had no emissions, which is why I was pointing out the parts that I felt were the most annoying.

The OMP rod never changes in length. You just have to add a couple angles to it to clear the UIM. If you're worried about it not moving the OMP's lever enough, open the throttle plates all the way and see if it pulls it fully open. If it won't move all the way, it's binding somewhere. This is the tedious part of the modification. Bending little by little, testing movement, and then bending some more. Vice grips help a lot.

You can use the S5 LIM, but that will introduce some other differences. The port air paths are different on S4s and S5s, so you'll have to seal up a hole & you'll never be able to pass an emissions test without some serious cheating. There are pictures in that writeup link I gave before.