just wondering what it is that makes the S5 have more horsepower than the S4 turbo's. bigger turbo? ecu? something to do with the engine itself? hmmmm.......

and anyone know why the freakin search function is down? jeese, it's annoying. wonder why it's down to begin with.....
scott

 

higher compression rotors, more effecient intake, more efficient use of boost.

 

different intake manifold or something? is that an interchangable part? and whatcha mean by "more efficent use of boost"? more of it or something? i can understand the higher compression part of it though. what could i do if i'm getting an engine rebuilt? it's the main reason why i'm asking the question to begin with. wanna make up for those few extra ponies....although i plan on having a lotta mods anyway. but every little bit counts.
scott

 

the s5 produces higher boost levels. its also has lighter rotors. the turbo is set up differently as well. a bunch of things changed. there wastegate is better too.(even though it has nothing to do with power) someone with a s5 should know better.

 

The engine had better porting as well.

 

Here's a chart of the difference in rotor weights & compression:
http://www.mazdatrix.com/faq/rotorwgt.htm

NA's: No egr valve, VDI intake, 1K more RPMs...

I'm sure there is more, anyone else?

 

okay well is it possible to get the engine built with 89-92 internals if the engine is the 86-88 motor? i'm about to buy the car but didn't think to even ask which year it was....but asking incase it is the earlier model. i plan on doing a lot of mods but if i can have the better engine, i'd like to have it. i'll have an external gate and aftermarket turbo, etc. so that shouldn't be an issue....

 

If you plan on doing some serious mods, the S5 engine is the way to go. It's basically like the 3rd gen engine. The S4 turbo is still a great engine though, just not as good. You can swap the S5 internals into the S4 engine isyou want, but hte lower compression is actually better!! You can run more boost and thus make more power. Lots of guys swap the S4 rotors into their engines instead.

 

sweet....and while i'm on the subject, i'm just curious. anyone know the max horsepower output from the stock turbo's? how many cfm's?

 

I just bought an 86 rebuilt engine that was modded to work with all of the 89 boltons, (intake etc)

so you could do it your self, youd have a lot of porting to do though.

 

Go to this site http://www.mazdatrix.com/ and see if you can afford to buy new rotors for a series five to put into a series four.

 

If you got the rotating assembly from an S5( rotors & counterweights) could you safely rev to 8,000 rpm. Or should you still stop at 7000 rpm??

 

well hopefully i'll have an S5 so that i won't have to worry about it. but does anyone know the max horsepower out of the stock turbo's? i wouldn't mind keeping the turbo in there for a bit so i can put the money elsewhere if i need it. depending on the max horsepower i can get anyway......

 

You can safely rev an S4/5 to 9k before you run into problems but this is saying the fuel needs are being met. Technically you could rev that high but you wont be making the power like an S5 would and your S4 ECU will only let you rev to 7800 (fuel cut/rev limit) what ever you want to call it. -Gabe

 

Could you be making good power at 9k (S4/5 NA or TII) with a street port? Again if the fuel needs are met.

 

More like 8k maybe 8.5k but it would be well past the redline. -Gabe

 

na's not having an egr valve? like hell they don't! it's directly on top of the intermediate housing. Go look at the fsm if you don't believe me. Mine shure had one before i put the turbo intermediate housing in it. (now theres just a blank casting face where one use to be)

The na's is located on the keg and the turbo's is located on the intake manifold somewhere on the back of the motor.

 

heck, i'd just make a blockoff plate for the egr valve or something. screw getting all that hot air into my engine!!! sure the egr valve isn't gonna help much when it comes to trying to prevent detonation....

 

too bad you can't rework the cooling passages to go where the egr gasses went. they're completely not entering my engine. those channels are filled with stagnant air on mine, but I'm na... I also run the S4 rotating assembly because i have the option to run more boost or mega nitrous when the time comes to use a power adder.

The arguement about the lighter rotors is kinda bs too. Sure they're .5Lb lighter and take less power to accellerate, but think about the dynamics of a turning rotor. How much of that rotor is actually more than an inch from the e-shaft? not much... The weight issue doesn't become a factor till well over 10K.

 

Well, this is a stock '90 NA engine.

http://www.zaxjax.com/Rebuild90RX7.htm

I don't know what to tell you.

 

Alright, i have seen in the FSM that the S5 DOES in fact have an EGR valve, and then i have heard from people that accually work on N/A S5 cars, and said they DONT! what the **** is going on here?

Oh yeah, and before you go listening to rotorific and reving your damn S4 to 9K+, be sure that those damn rotors dont get all wobbly wobbly on your *** and rip themselves, and the bearings to hell and back. The blocks arnt blueprinted nor are the tolerences tight enough to run that high on an S4 (smoothly, saftly) At least i wouldnt do it.

 

My turbo II intermediate housing doesn't even have the threaded holes for the egr... I have an S4 and I rev the **** out of it. Mine had the egr valve on the top of the block. It's possible that the s5's use the ACV for the egr function entirely. OR, its mounted on the intake manifold.

 

While we're on the subject of high rpm's, don't forget there is a marking on each rotor (A,B,C,D,...) corespoding to the minute weight differences (from manufacturing I suppose). If you want the best balance check the gear side of the rotor and make sure these letters are the same! A letter off for regular driving is OK.

 

I know, when I pulled this engine, I was thinking it was a one of a kind because it had the egr bolt holes but no egr valve hole. You learn something every day.

 

Maybe someone screwed up and gave that car a hybrid motor from the factory? Some quick drilling and tapping would make the engine "look" right, and we all know how well they run without that pesky crap attached....

I'm curious if theres a different computer in your car without the egr on the housing than those with them? Maybe they did just make the ACV do all the work. Seemed like a redundant system to me when I first saw it.