i have read the differences but is the s5 just a much better motor then the s4? also can you swap out the s4 motor for the s5 or is their a lot involved with that?

s4 turbo motor swaped out for s5 turbo motor

 

No. There isn't any major difference between the s4 and s5 engines.

edit: Don't swap engines between series, it's not worth the hassle.

 

Not any major differences?

Then why does one motor have 15 more HP than the other?

 

I always thought there WAS a difference...

 

15 more HP = major difference ???

 

don't the s5's have higher compression than the s4's? Other differences too, but that would make a difference.

 

there are alot of differences
housings rotors, bearings... little things that add up...
the major difference between the two turbo motors is boost.

s4 is 5.5 while s5 is electronically controlled to receive about 7.5-8 i believe it is.
thats where the 15 hp comes from.

There are many threads that state theses difference....do some research.

 

S5 engines have lighter rotors IIRC. Check the FAQ.

 

i prefer the s5s in general (the look of the whole car and everything). there are differences but rb_eater is right, it so not worth it to swap between series. i feel bad for the guy with the s4 that i sold my s5 motor to

 

its actually not that bad of a swap i have a jdm s5 t2 motor and tranny dropped into a s4 gxl and there is a big difference lighter rotating assembly better intake bigger turbo better waste gate and manifold just use a s4 t2 harness and your s4 injectors to run your s5 motor and premix trust me not that hard just some work

 

newer is always better

 

There's a reason Mazda changed the motors. Newer is better.
Higher compression, higher boost, higher revs, lighter motor, better flowing motor....

 

Theres many changes that make the s5 a better engine, some have already been stated. Larger runner higher flowing intake manifolds, rotors are lighter and have higher compression ratio, the turbo has a much better divided manifold and turbine housing with a better wastegate design (the rest of the turbo is the same), the rotor housings have a slightly lower spark plug positioning, the list goes on and on. If your doing a swap and have a choice between the two engines, get the s5, its a no-brainer.

~Mike..........

 

i prefer the S4 turbo block b/c of the lower compression, it gives you a bigger safety margin when running higher than stock boost. i wouldnt say there is that big of a difference, the S5 TII only made 8% more power than S4 TII.. another psi or so of boost will easily make that up, and you have a more reliable setup with lower compression

 

the s5 rear iron is also better for making power (in referance to the rear housing on the s4 cracking at the dowl)

 

higher compression is easier to blow when you add boost

 

And you make more power with the higher comp rotors at the same boost then the lower comp ones, not to mention quicker spool up and better off boost throttle response.

Hardly any of you guy are running real turbo's and high boost anyways, so the whole "safety margin" is crap. You want a good responsive street car even making stupid amounts of power (400 to the wheels) then the s5, s6 rotors are the way to go. Off boost is much crisper (higher comp), it'll spool faster (or spool a bigger turbo just as fast as the low comp smaller turbo engine), rev quicker (lighter weight) and make more power per unit of air, period. This isn't a matter of opinion, these are FACTS. The only matter of opinion is if you need lower comp rotors for a safety margin (you can't tune or get decent gas {and even if you can't tune, lower comp rotors aren't going to save your ***}). If you’re a drag racer and want to run 35 PSI from your GT45R turbo then sure, the older s4 rotors may be the ticket due to the lower compression and thicker castings in the faces (ever see a dented rotor?) but if you are a drag racer, you wouldn't be reading this as you'd already know this.

If you already have a s4 turbo car, and have the option to get an s5 engine then do it, you'd be a fool not to (<--- the only opinion I've given). Use the s5 turbo, manifolds and engine and just use the rest of your older accessories so your wiring harness plugs in (may want to change the front cover to keep mechanical OMP and older water pump/neck).

So what, some you going to say the s4 are better than the s6 engines now too? Ohh, and the 13B-RE?? Each generation was improved.

~Mike..............

 

You guys are missing the most inportant part. The ECU. It is a whole lot newer and easier to deal with in my opinon. Yes it's worth the swap and yes it's much better. S5 doesn't flood either. S4 is a piece of crap especially the turbo and manifold design. Before someone jumps on here and says "my S5 floods" remember your car probably doesn't even work right whether you know it or not so don't post. S5 is leaps and bounds ahead of the S4. Why does the S5 not have an EGR valve and a couple others thing the S4 does? Because the fuel injection system is better and more tightly controlled. Although it's still not great when you compare it to even a OBD 1 Honda ECU but considering it's still pre-OBD it's not too bad. There is a reason the generation ends in 91 so they never had to make a chssis with pre-obd then obd-1 for one year before the FD came out which is only OBD-1 obviously since that chassis is stopped before OBD-2 was enacted for the USA. Basically only Japan and the other countries have an OBD-2 RX-7. New ECUs are always better for every reason possible. Not saying RX-7 ECU are even worth a **** in the first place though. But both of my S5 ECUs work fine.

Just the other day for me is a prime example. I went to my buddys house to swap my Porsche Stern wheels for his stock T2 wheels. (and money of course) He has a S4 and everytime but the very first time he started it that day it was flooded. My car started evertime all day under all conditions. Needless to say he was quite jealous and he even said he might want me to help him change it over to S5 so its easier to deal will. But for now hes flat broke and can't buy the parts so it will be a while. My FB even has a S5 motor I mean come on at least a S5 motor belongs in your chassis and you can convert it easialy. I went from a 12A carbed to the full S5 swap (NA) it's not even hard to do that.

 

That only matters if the car is not tuned correctly. Its not that much more compression. .5 up to 9.0:1 that isn't anything. There are countless people running big boost on comp ratios that high. Find another reason to not do the swap like: "I can't afford it" or " I have too much money and parts invested in my S4 setup so I can't switch now" not .5 on the comp ratio that's stupid.

Remember the slight comp ratio gain will make the engine drive better off boost and give greater driveability at lower rpms when the turbo is upgraded or stock.

I wasn't picking on you it was just easy to quote you for my purpose of explanation.

 

wow thank you everyone for your responses, i got an offer for a s4 but i was wanting to swap out the engine for a s5 turbo instead thats why i am asking thank you again.

 

Wow.. thats why a S4 floods too, because something "doesn't even work right". But thats the only prob I have with your post, I agree with the rest.

 

hey it all comes down to prefence and money if you got it everything is possible i choose the s5 cause it seemed to me the better swap and i just got my microtech in from australia and damn that took a while to get it i am keeping the stock turbo and everything cause i do want this streetable but fun but newer is allways better usually depending on what you are lookin for

 

You are exactly right I just didn't want to have a guy say all S4 T2s flood because they don't. I just fixed my buddies a couple days ago. It has been having the flooding problem for about 3 years now. Now it works perfect like normal. Wiring problem of course. Now we just have to fix the turn signals and the car works perfect. His harness has caught fire a couple times over the years due to improper electrical fixes. We actually removed the entire harness from the car and fixed it all in one shot. Missed the problem with the turn signals but considering the amount of work that went it to fixing the rest of it I'm not dissatisfied with only one thing still messed up out of all the problems that exsisted. Not to mention the blinkers is an easy fix he just lives 45minutes away and its hard to get a time for both of us to meet up

 

i see your point on the compression. Also, that engine stud area on the front plate is much thicker on the S5. Maybe the only REAL benifit to going S5.


In reference to the ECU being SO much better..
Come on!!! Really, much newer and so much easier to deal with. It doesn't have OBD connections. I mean, really, for anyone trying to make power on these things, they are going standalone. So moot point.