aka_rocket

so like the title says.
i will be rebuilding my motor during this winter break (1 month off, YAH!), nothing blew but its running not so good at the moment. low compression and oil leaking, bad seals. i was wondering since i have a full s5 motor to work with and would like to do the mod. After reading the write-up that was written about swapping the s5 intake manifold onto the s4 block, i'd be nice to take advantage of the improvement of the s5 intake manifold design. my engine will be a hybrid so that's why im asking and it being my first rebuild, it sounds exciting my make me nervous.

for those that have done this mod, would you recommend i finish rebuilding the motor and letting it break in first with the s4 manifolds and making sure it works before doing the mod. the other option is, i was thinking if possible, just doing the mod as i finish the rebuild so i don't have to take the s4 stuff off again later. i would probably do a little porting too since i hear it won't affect the emissions for the n/a like it does for the turbo. could i just take out the diffusers?

im in cali so i will keep all my emissions and probably get the pineapple 6-port sleeves since they seem to be worth the 50 bucks they cost (from what i read from another thread).
would this present any difficulty for a freshly rebuilt motor or would it be fine.

i will be using all s4 stuff except the dyanmic chamer, lower & upper intake manifold.
it will have s5 rotors and housings and the complimentary stuff. quick side note, are there any difference between the s4 rotor housings and the s5 rotor housings or are they exactly the same. i've never had two housings side by side to compare before.

any other question that comes to mind i post.
thanks.

aka_rocket

anyone with any thoughts?

Icemark

#1 yeah... It helps if you start off by telling what car you have… example: I have a non turbo 88...

#2 The swapping the whole S5 intake onto a S4 block has time and time again proven to be a loss of lower range torque and HP. The only real HP increases will be with port matching and polishing the middle and upper sections of a S5 intake to a S4 lower intake. Remember the S4 LIM is considerably larger and better flowing than the S5 LIM.

#3 it will be impossible to pass CA visual (and possibly test) emissions with a S5 intake on a S4 car/engine, as you will need to remove the EGR valve to fit the S5 intake (even if using a S4 LIM).

#4 porting the engine will increase emissions as well and may make it difficult to pass CA emissions tests. My S4 vert with a Hybrid S5/S4 intake, street porting and no EGR just squeaks by emissions and probably would not if I didn’t have a new main cat, new Iridium plugs and new air filter, and de-tuning tweaks when I last tested.

#5 You do not want to remove the exhaust diffusers unless you want to increase exhaust sound considerably.

#6 There has been some serious issues with the pineapple sleeve and I personally know at least two rebuilders that will not touch them or install them. You may wish to rethink them and search here on the subject.

#7... The S5 engine rotors are indeed lighter; however this generally results in slightly lower torque levels on a N/A motor. Depending on how and what you drive, really should determine what rotors you use. If you see a lot of street driving or street/strip red-light type racing, then you are better off using the S4 rotors. If you are driving road courses or other higher RPM driving, then use the S5 rotors.

And please do not bump unless at least 24 hours have gone by. Otherwise people will think you are an impatient baby and will not really want to help you.

pengarufoo

Icemark

and what did you not understand about that???

Even Mazda found that out on the S5 non turbos, where they are lower on torque on everything below 3800 RPM than the S4 motors and even at 4000 RPM (the peak torque on a S5) the Torque is only up 3 ft/lbs over what a S4 does at the lower 3500.

So even though Mazda [on the S5] non turbo, reworked the whole intake, used higher compression lighter rotors on a S5.. there was no real increase in what actually drives the car forward... torque.

Instead, they made an engine that revs higher (on manual tranny versions).

aka_rocket

sorry, didn't realize it. i have a stock 5spd 1986 gxl. thanks for the insightful/informative response. it was a possibility i was thinking about.

theone81

<img src" http://www.teamfc3s.org/forum/attachment.php?s=&postid=85796">

pengarufoo

The heavier, lower compression rotors do not result in more torque. You are likely confusing things with changes that resulted from their new intake design.

If you truely believe the S4 NA rotors make more torque than S5 NA, please explain this, because it makes no sense just looking at the physics involved. Sounds like the person arguing that a heavier flywheel makes more torque.

RotaryRevn

.

Icemark

No, the changes in intake design netted more volocity at higher RPMs. The S4 design runs out of power at 6K- 6.5k, the changes with the S5 design allowed a much higher run out of intake volocity. This increase in intake volocity (along with the engine managment) are where the big HP increase came from on a S5.

It goes both ways... if you truely believe that the S5 rotors make more Torque prove it.

You can't; even though the increased compression (of a S5 rotor) should do just that... there is no real increase in Torque. Increasing compression on other 4 stroke engines always nets a increase in torque... why does it not on a S5 non turbo motor???

But my statement was not that the S4 rotors make more torque... but that the chamber design and increased weight produces pretty much the same torque at a lower RPM. Lower RPM peak torque helps in over all accelleration from a stand still... so I stand by my recommendations. Lower rev'ing strip/street motor, S4 rotors... , Road race/higher RPM peak HP use S5 Rotors. And stay away from Renisis rotors for they really are no different output than S5 rotors (despite further light'ning) as proved by the good people at Mazdatrix (and RB as well I believe).

But engine builders can come in this thread and contradict me as well... But after speaking with several at 7 stock this year, who all agree'd with me on this, I would be surprised with very many highly experienced builders disagreeing with my post.

And a flywheel can not make more Torque or HP. It can make the illusion of more power, but it will never change the output of any engine, much to the dismay of the Bozos who think that putting on an electric fan also increases the HP.

aka_rocket

my car will probably be seeing mostly road races/autocross and not so much from a standstill. since the S4 LIM flows better then the S5, could i just use the S4 LIM and adapt the S5 UIM onto it. i'm probably still gonna use the s5 rotor because my motor already has 170,000 on it and the 91 rotors only have 120,000. the none or little change in the amount of low end torque shouldn't affect me that much, would it if this was a roadcourse car.

RylAssassin

Great thread guys, very informative.

*rx7drifter*

does anyone know how to put a s4 manifold on a s5 engine

inflatablepets

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

I put S5 externals on a S4 block. It seems to really kick in from 3800 rpm to 7200rpm. The power feels like it starts to fall off above 7200. I have been able to pull fairly well on S5 N/A cars with this setup. I don't understand why you don't just rebuild the S5 engine and put it in. I suppose that it's an emissions issue.

Mark. Can you tell more about this issue? Why, and what are the problems?
#6 There has been some serious issues with the pineapple sleeve and I personally know at least two rebuilders that will not touch them or install them. You may wish to rethink them and search here on the subject.

Icemark

That old write up has a few errors and things that we have since learned are not done right.

as far as the pineapple sleave thing, Kevin (rotary ressurection) had big thread on it here and on team FC3S

inflatablepets

And these errors are? Like I said, I pretty much did this swap, as far as adapting all of the S5 stuff onto the S4 block. I had to grind on the rear iron, block off the split air port, and remove the EGR valve. My car runs perfectly with all of that done. I passed the emissions very well too. Thanks for the info on the Pineapple port sleeves. I'll look into it as soon as I am done posting. At the time, I was considering using them.