I have an s5 and I need a motor badly i found this one:

Engine: S4 block, HBP on top of large street port, 9.4:1 rotors, RA seals, mazda oem springs, FD oil system, FD stationary gears, e-shaft oil mods, will come with the Mazda Racing Pulleys. no flywheel, it is being sold seperately. I guess i can ship this but would obviously prefer pick-up. engine has less than 1000 miles on it and has seen 2 oil changes. it is being removed this weekend and i will be taking off the oil pan and pick up so it can be stored safely. you will recieve these pieces with it ofcourse. THIS IS A BLOCK ONLY w/ waterpump and alternator + MR pulleys, it will not include manifolds!
$ make me a fair offer!

What I was gonna do is take all of my stock S5 manifolds, turbo and all other stuff on this S4 block and run it for the first 4 or 5 months until I have to store it for the winter.

I know I'm gonna have to change the front cover that's not a big problem.
What I wanna know is what rear counterweight should I use on this setup with my HKS light flywheel + clutch setup ? I do not know if the rotors are 13b FC non-turbo or FB rotors or 12a rotors. If it's an 13b fc oubviously i would need an s4 rear counterweight. But if the rotors are from an FB or 12A what do I do ?

And also I have a J-spec chipped ecu and harness S5 (N370) will my ecu and harness become compatible on the S4 Block ? Considerings the fact I have stock S5 fuel rails and injectors and the S5 harness has a couple of sensons that the S4 did not have. Like the knock sensor + omp sensor and i dont know what else. Already the OMp is blocked off and I have to runn a premix that's 1 sensor off my back.

So basicly the fornt cover I know someone who can deal with that for me. I need to know what I should about the ecu, the harness and the rear counterweight. And if anyone can think of something that I might have left out please let me know.

 

the conection to the ecu wont match up, different technology, and different amount of pins on both ecus

 

you'll need a standalone to run a bridged motor

9.4:1 rotors are S5 so you will need an S5/S6 counterweight

bridgeports breathe, alot, so you'll need more fuel than you probably will be putting onto that motor.. at least in boost it will.

 

I understand I will need a stand alone sytem for this setup but right now that's not my priority I need an engine NOW. So if I were to use the S5 harness & ecu on the S4 block it wont match, even though everything that's gonna bolt up onto the block is S5 ? hmm......

And by the way 9.4 rotors are S4 non-turbo. there's a chart on mazdatrix in the FAQs.

So basicaly from what I read it's like it ain't worth it for me to get this motor now is it ? But even if I can somehow make the ecu and the harness compatible would it be worth it to do the swap ?

I already have a lot of mods on the car as it is. FCD, dual alt pulley, HKS clutch+ flywheel, HKS exhaust, walbro fuel pump just to name a few.

So what's everyones opinion on this ?

 

Unless I am VERY mistaken, 9.4 rotors are s4 NA. s5 NA was 9.7. You will need the s4 rear counterweight.

 

Yes sir, you are correct.

 

IMO if its only a halfbridge you should be able to run it with the s5 ecu, it will need fuel mods and a wideband + fuel computer to be run hard, but it should run. you will need to strip it to the block and swap all your s5 components i.e. intake manifolds, throttle, all sensors, front cover. check in the 2nd gen tech section at www.rotaryresurrection.com kevin has a good write up on it.

 

I hope your right RX7ridah. But I'm still not 100% shure. And yes I read the thread on rotaryresurrection.com on the S5 to S4 swap. I have the front cover and I know someone who can do the job for me. Right now my priority is getting an engine and my concern is making it run with what I have.

Here's a list of mods:
Complete conversion from an s5 n/a automatic to an s5t2 5spd.
Mazdatrix custom driveshaft to go from a t2 tranny to a non-lsd diff.
Racing beat dual alt pulley
Racing beat emission block off plates
Racing beat Oil baffle plate
HKS Air filter
HKS Downpipe
HKS Silent Hi Power Exhaust
HKS Lightflywheel + clutch + HD pressure plate 6puck
HoseTechniques Sillicone vaccume hoses
Walbro Fuel Pump
Apexi BOV
Ultra Power 8mm silicone spark plug wires
S5 Koyo aluminium rad
S4 ported throttle body
SS clutch line
S5 fresh rebuilt turbo

Now with all that I've got is it worth it for me to get an s4 HBP block with all these performance parts + keeping in mind that everything else I have is from an S5T2 stock. (Manifolds, Fuel rails, injectors, tranny,etc.)

 

Oh it will certainly run, but it will blow up when it hits decent boost...and based on the mods list below, he'll be in boost virtually all the time. Also be hard to start, nearly impossible to drive in traffic, smoke like hell, etc. The stock ECU is unsuited to run a bridgeported engine. High overlap ports like bridgeports behave radically different then the stock ports.

I've snipped irrevelant stuff out of the mods list...

There's no mention of an FCD, but that's only a minor problem.

On a half bridge engine, the S5 turbo will be in boost constantly. At anything more then 20% throttle you'll be in boost, and on the highway you'll have a hard time not making between 4 and 6 PSI. This is because the bridgeport really gooses the turbine, and the engine simply flows much more air. With an open exhaust like the one above you'll never be able to stay out of boost.

Part of the reason is that the stock turbo is WAY too small. In order to stay out of boost using the stock turbo on my car I couldn't go over 15% throttle. Driving on the highway was a joke...4-6 PSI constantly and thus about 2 MPG.

If you want to make power, the stock turbo won't do the job. 275HP at the most.

 

Thanks alot for the advice Aaron Cake. I'll be honest my goal with this motor is to get th maximum power output out of the stock turbo and from what I've read on the forums and tech supports pages I know I can boost the stock turbo to a max of 14.8 PSI which is what II'm going for. But for shure with a fine tune I will be more than satisfied with the results. BTW yes I have an FCD from Knightsports and a J-spec chipped ECU that I forgot to mention in the mods list.

But let's say for example I run this setup on the S4 block with my S5 components what's the worst that can happen. Blow the engine, injectors bursting under pressure, engine always flooded, what's the worst that can happen ?

 

It's very unfortunate that the engine is bridgeported with your goals in mind. A simple mild street port or even a stock port with the high compression rotors and you would have met your goal. Since the engine is bridgeported, you now have to deal with the complication of running a standalone EMS and tuning a setup that is not for one without experience. The fact with a bridgeport is that it's a hard thing to get running just right, and the around town gas mileage is less then half of that with a stock/street port due to the overlap. Using only the stock turbo, the bridgeport is wasted and may even cost you power in the low and midrange (due to the backpressure created by the small turbine).

If you had a shop build this engine for you, they should have been very clear about this before they took your money. If you built the engine yourself, you should have researched and been honest with yourself regarding power goals. Not blaming you, just letting you know what you're in for.

I'm wondering where you got that max boost number from? While it's generally agreed that the stock turbo is getting useless after about 12-14 PSI, 14.8 is a very precise number to base this assumption on... Generally at the high 12s the stocker is running out of breath and by 14 PSI it's pushing more heat then air...The compressor is just much too small.

You should be very skeptical about what a "J-spec chipped ECU" means. Do you know how the timing and fuel curve was modified? What injectors was it designed to work with? Either way, it's not going to run a bridgeport very well.

If you use your stock ECU, the car is going to be hard to start, get horrid mileage, smoke, backfire, sputter at low RPMs, buck in traffic and make low power. Once you are in boost, you must use piggybacks to control it and modify fueling appropriately. You can probably make it perform well at WOT, but that's about it. You'll have issues with making the transition between primaries and secondaries smooth while preventing a lean spot (popped engine). Ignition timing will be too aggressive and there's no way for you to fix that. You'll need larger primaries due to the low spool RPM of the turbo so you'll get even harder starting and the car will be prone to flooding.

 

right, i was thinking 9.0 was the S4 n/a rotors for some reason when i posted it.

 

From R.P.M.'s trials with a HBP and stock ECU, I can finish this scentence

unable to complete any other action then simply starting and idling. Under any load at all the engine will fall on its face and simply buck the carp out of your vehicle.

It seriously will not work in most any capacity.

 

Thanks alot for all the advice. So I guess either I'm gonna have to get a Haltech stand alone if I decide to run the HBP engine or a rebuilt S5 block to use with my stock components. All in all I learned alot from this thread and will be doing more research in terms of performance or power. Thank you all. We will keep in touch.