Hey I was thinking about maybe putting a turbo on my na s5. I heard that with the s4 rx7 you need the s5 rotors because they are a lower compression than the s4 rotors. since i already have the s5 rx7 i was thinking that i could possibly use a turbo that will give me a little more power but not so that it is too big a turbo so the engine wont blow. I think that maybe a t25 turbo would be around that range. anyone have any advice for me? thanks guys p.s. it is just an idea right now, if it is not safe than i wont but if it would work then cool.

 

im in the same boat

 

We need to clear some things up for you here.

S5 TII and S4 TII rotors have lower compression than their n/a counterparts.

S5 rotors are higher compression than S4 in general.

Adding any forced induction without supporting upgrades will result in a blown engine. Doesn't matter how big or small the turbocharger is.

 

ok, i was mixed up with the compression on s4 and s5. well then i guess i should just do something like a street port.

 

hey dale what kind of rx7 do you have?

 

me?
my name is ken lol
i have an '88 n/a
there is pics of it on my profile

 

you can do a turbo on the high compression rotors, you just have to be really careful about how you go about it. When Macz says you need the supporting mods, that means better fuel pump, injectors, generally standalone ems, or at leas a way to control fuel (ie SAFC). There's more, but that's just to give you the general idea.

 

This is exactly what I was going to say after reading your first post. Maczpayne is dead on and knows his stuff, so take his posts seriously.

Like what he said, it can still be done. Aaron Cake built a turbo'd N/A that turned out very successful, so read through his build closely to see what you're getting into.

 

Aaron's turbo N/A was an S4. many people are of the opinion that there's no way an S5 6 port turbo can work. the compression is just too high. a full standalone and many supporting mods would be necessary. aux. injection of some sort could help as well. I suppose an S5 with S4 or S5 TII rotors could work, but that would be a pain.

 

Guys read the FAQ and Search.

I have also done my own thread or two really trying to find a way to turbo an NA, even on the cheap side with access to cheap parts it is not worth it, unless you are going Aaron Cake style and doing it for the sake of doing something different, unique, or for philosophical reasons.

There is absolutely no reason you would want to turbo your running NA engine. The amount of costs and parts and still having something that will likely grenade on you is pointless. Just get on Ebay, type in 13b, buy a decent priced Jspec with tranny and harness and go from there.

I heard this a few times but you really need to break down everything you will need and it is pointless.

 

T25 is way too small. It will be more likely to blow the engine then a larger unit.

In my opinion, the S5 NA compression is too high to reliably turbocharge.

If you really want to do this, get off the idea that it will be a low budget project and start with purchasing a standalone, larger fuel pump, bigger injectors and get those running and tuned on your NA. Then build a turbo manifold and all the appropriate turbo stuff.

 

So it would just be cheaper to do a full turbo swap :-\

 

exactly my point.

 

Hmmm, cheaper, probably not.

I am in the process over the next year, of building up my turbo N/A. But, I am going standalone, pulling the motor, rebuilding and porting, new seals etc.

Buying a JDM is a gamble. And, you may end up needing to rebuild that anyways. For me, I figure, it is cheap to just rebuild my current motor, and prepare it for boost, rather then buying a T2 and rebuilding it. Mostly because then you have the cost of the T2 and the rebuild. I may try and find a cheap T2 motor in a junkyard and rebuild, but not too likely right now.

Turbo won't be cheap. I have $5000 or so planned right now. Which, I still don't think will be enough.

 

Don't live by what you read on the internet. I'd say that 90% of the people that are posting in this thread have never done an S5 6PT setup. If you're worried about it blowing up, take the turbo to a machine shop and have them port the **** out of the wastegate and run 3psi If you want to be even more paranoid, buy a windshield washer pump/reservoir, a nozzle, a boost activated switch (all for less than $100) and spray water into the intake over 3psi. Or if you really don't care about power, back off the CAS a few degrees. This is really retarded though, since if you run it off the wastegate spring it will be fine.

Everything from a turbo engine damn near bolts onto yours with slight modification. Don't be retarded and buy a POS J-spec. 0.3 difference in compression (S4/S5) ratio doesn't mean ****. Just because some people don't like to make a website with 10,000 pictures and descriptions about a project they've done doesn't mean no one has done it. If you search there are TONS of people that have ran S5 6 port turbo setups and ran extremely high boost (18psi+) on the 9.7:1 rotors. The reason they don't post build threads is because if any dumbass internet nerd (like the ones posting in this thread) disagrees with the way he did something the whole thread turns into BS.

Some of you guys are pretty ******* ignorant. Re-read his first post and then reply with an appropriate answer he apparently could care less about HP output as long as its slightly higher than his NA setup which allows him to run the necessary power-limiting safeguards. /end rant.

 

Ignorant? Haha.

Guess everyone wasn't born knowing everything huh? Must be nice.

 

Almost all of my motors used S5 NA rotors, haven't had one fail me yet and i've abused them in most every way imaginable.

 

Aaron-I have heard this type of statement before and don't entirely understand. I am not challenging the validity of it, just trying to understand.

I do understand that the 'small turbo' will run out of air relatively low in the rpm range, thus limiting the peak Hp. So maybe the turbo would give some more low to midrange without necessarily holding the boost to redline. If the wastegate were set to 4-6 psi and properly ported, the T25 would run out of its range and maybe at engine redline there would be only 1 psi or even maybe *no* positive boost. Other than over-speeding the turbo, reducing it's life what else would happen?

Why would it be more likely to blow the engine than a turbo sized to match the upper rpm range of the N/A 13b? In the old days (and I do mean old days-I'm a relic) this was the only way turbo's were matched. The turbo was sized to run out of boost at the peak rpm. This was in the carb blow-through days, so we didn't have to worry so much about fueling, just boost and timing.

Thanks in advance,

Jack

 

There are also a load of people who have blown engine after engine after engine. Those who can keep them together (like SonicRaT) obviously have the skill and have done the build properly. Any high compression turbo rotary (S4 or S5) isn't something that one should just dive into. And the bump in compression with S5 makes it a bit more difficult.

He should choose another project then. Slightly more power then NA means just bolt on a header, exhaust, intake and standalone. Or swap a TII.

You're one of those who has the skill and can do things properly.

In order to make any appreciable power gains, the boost needs to be cranked. The turbo will be run out of it's efficiency point trying to produce airflow like that and compressor outlet temps will skyrocket. Exactly the same issue as cranking the boost on the stock turbo, except that a T25 is smaller then the stocker.

Then there is the tiny hotside that will be nothing but a reversion generator. It will be a major cork in the exhaust around 4000 RPM and just build massive backpressure and pre-turbine EGTs.

 

That's sadly the biggest issue with any performance upgrade I think. Even on mostly stock cars people ignore so much about it and it comes back to haunt them later. The majority of the people who just want to slap on parts are the same people running 5 year old coolant/original fuel filters/etc. It takes a good bit of work, thinking things through and doing things the right way to keep everything together.

 

So, what exactly should the person do before he "dives" into it?

In all the searching I've done I know of ONE guy that blew a couple of engines and he was using junkard/parts car engines, swapping them in the same day and running 8psi. I also believe there were other things wrong with his setup but I don't care to dig up the thread.

Intake does nothing, a standalone+tune has an extremely unfavorable cost/HP ratio and the exhaust will probably net him maybe 15 peak whp and cost $500+. And at last buying a J-spec engine and having it rebuilt is $2500. He can build a VERY sick, reliable 6 port turbo car that makes at least a 100whp over a stock TII for that much. Don't waste a good engine.

Maybe the OP only wants a turbocharged car, and the BOV sound, or the increased torque, a cooler looking engine bay, WHATEVER. Don't assume he is building the car to impress you or anyone on this board. If he does his research and spends the money in the important areas (doesn't mean more money) and not on stupid stuff (colorful fittings, polished parts, silicone vacuum/coolant hoses, fancy ****) he will build a reliable boosted car.

And the problem with a T25 is the hotside is probably too small, compare it with a stock one to make sure. Small hotside means the boost drops when the backpressure builds in the housing, so imagine getting 8psi by 4000 rpm and watching it drop to 4psi by 7000rpm, not fun. If you really want, you can compare the wheel dimensions and map to a stock turbo (thread by arghx) and see if at least the compressor will work.

RX7TYREBURNA: First off, just because my post came right after yours doesn't mean it was directed towards you. Second, you are quite far off with your judgment. I've never had friends, family or anyone that taught me about cars. In fact they'd all tell me I was dumb for being so obsessed. If you learn from people that have had experience (books, searching here, google, turboforums.com) you will have no problem learning anything you wish. Don't start from scratch.

 

I've rebuilt at least 5 myself from people who've blown theirs with bad N/A turbo projects.


Most of the items you mention here will also be required for a turbo 6 port as well.

 

A semi-local owner went through like 4 decent rebuilds trying to get his before he gave up. I know of a few others but truthfully, they were junkyard setups.

I'm not sure what the setup is on your car. Is it a S5 NA-turbo and is it holding up?

Way back in the day, when my car was NA, I had a Bonez cat and my own catback. Back to back dyno runs of the stock airbox versus just sticking a cone filter on the AFM showed a 5 HP gain.

Yes, bit it will get him to the mystic 200HP NA mark that a lot of people want and lay the groundwork for the turbo project. The tuning knowledge gained by tuning the much safer NA car will serve him well and thus he won't blow up his turbo-NA engine. It would be on the very high side of that $500+ though. Even an "inexpensive" Megasquirt install will run into $1000 when you consider all the extras needed to make a non-ghetto standalone install.

This may come as a shock to people, but not every J-spec needs to be rebuilt. I have installed "off the shelf" J-specs without a rebuild (REs and 13BTs) that have run for 50K + on aftermarket turbos without being opened. From a rebutable dealer that stands behind their products, the only thing you have to lose is time if the engine is bad. But a reputable dealer will buy from reputable yards in Japan and actually have a good product in the first place.

There are also other choices besides. A rotted TII that runs well is a great doner for something like this.

Yes, if the research is done and he proceeds in a logical way, then the project will turn out. But, and this is a big but, it's clear that no research (even a basic search) has been done. Suggesting a T25 is the first clue. And not knowing the compression of his rotors. Everyone has to start learning somewhere but honestly I don't know if there is another topic covered as extensively as turbo-NA stuff. It's a major irony that there is so much information out there for something that most consider "ghetto".

A T25 is way too small on all counts. Two of them will make about 300HP on a 13B and run out of flow by 6000 RPM. Most of the factory sized turbos are made for small displacement piston engines. People look at them thinking they will save money but in reality, I am fairly convinced that a good number of rotary engines pop because of improper turbo sizing (which includes using the stock turbo at higher boost).

 

i have an s4 n/a and im going turbo, ive done research and still am as i read this post, but i also will have something to help me come to my final conclusion, As my friend will be droppring in his turbo 6 port turbo in this week. some things i know will be needed are a standalone im Going microtech 520 primaries 760 secondaries walbro fuel pump custom intake manifold etc.......I will keep all of you notified to how it comes out and this wont be my first encounter with a 6 port turbo as its not my boys first engine built he is just running some new things to better support the set up

..... Aaron cake i checked out your page as well and it helped but i wanna know is your engine still running?

 

My setup lasted 5000 miles before it had an unrelated failure from all six springs flattening out and wearing down the seals and eventually losing compression (you replied in my thread). The engine was a rotary ressurection rebuild with ~60k so I believe the springs were reused. Now with a rebuild and streetport its holding up fine running the stock TII ECU and sensors off the wastegate, full details are in my sig. I haven't been driving it as hard since with the streetport I am probably pushing my current fuel setup.

If he's happy with 200 peak whp with nothing down low with a maxed out setup then more power to him, most people aren't. Especially after spending $1000...lol.

As far as J specs, NO one with a 2nd gen has $1000 to gamble. If you want it from a reputable seller, be ready to pay ~$1500 for a used longblock. And then you buy everything that you could've otherwise put on your own block Just to have a "reliable" car when you could've put the money into reliability mods (AI, intercooler, engine management etc), use your known-good block, make more power and have better off-boost response.

And of course he doesn't know anything about it now, maybe he wants to see what he's getting into before he spends hours searching and reading? Don't babysit the ignorant people and discourage the competent people and make people feel like their cars are worthless.

And they must have been doing something obviously wrong. Yes those things will be required for a 6PT, and it will yield FAR better results than if it were on an NA engine, with the ability for him to change setups and shift the powerband and characteristics of the engine wherever he wishes.

In the end, people often fail to realize how easy it is to discourage someone when they are well respected members of the community. You can do whatever the hell you want if you educate yourself and show dedication and competence. Let the ignorant people blow their **** up and make examples.