ma71supraturbo

My friend is looking to get an 89-92 rx7 for road course, back road, and drift use. He's in the early stages of looking for a car, but would like to get a 250hp "bulletproof" horsepower at the crank (to make the car as close to 10lb/hp when gutted). Which platform would cost less to make the car worthy of running 6 hours on a desert road course -- then drive home (maybe two or three times a year)? The real kicker is he would like to be able to smog the car every two years without having to spend more than an hour or so switching parts...

From the search I've done, I gather that the GTUs would be the NA to have, but I never see any for sale. Does the regular NA have a really weak transmission (heard the GTUs upgraded to a TII transmission), or can it hold it's own?

Finally, does anyone have a link to a staged modification/upgrade list for both the NA and TII?


Thanks a bunch for putting up with my noob Q's. I'm sure they've been asked before, but after spending a few hours searching I figured I'd take my chances of getting flamed :flamesuiton:


Jeff

1987RX7guy

iTrader: (3)

Turbo

Syonyk

The regular NA transmission is generally considered to be good up to 200 HP. Anything more than that, and it WILL break in time - just a matter of how much power you're putting through it and how you drive it. It doesn't sound like he's going to be babying it, so you'll need a turbo drivetrain. This also includes a clutch type LSD in back.

You can get 250 HP out of a NA, but it's really pushing it, and involves some ports that most likely won't pass smog. I'd say go with a turbo.

-=Russ=-

RotaryEvolution

iTrader: (30)

turbo

Icemark

250hp on a non turbo is not going to be easy, inexpensive or reliable. If you are looking for that sort of HP then you will want a Turbo RX-7

The GTUs (as all non turbo coupes) comes with the standard M type tranny. It is not any stronger, or any different than any other non turbo coupe tranny other than a different 5th gear. The idea that the GTUs comes with a Turbo's R type tranny is BS and from people that don't have a clue.

Unfortantly all the 89-91 coupes were much heaiver than the S4 (86-88) versions. If you really want a lightweight car as described the 86-87 Sport or 88 GTU would be much better choices, as they are about 200 lbs lighter than the 89-90 GTUs. The stock 86-87 Sport was only 1/2 second slower in the 0-60 than the 87-88 Turbo.

RotaryEvolution

iTrader: (30)

the GTUs is also very expensive to pick up since it is the rarest model RX7 and people might have objections to him stripping it out and beating on it.

RX7goZoomZoomBoom

Turbos both suck and blow if he is looking for reliability and consistency on the track then an NA is the better choice. No matter how much you do the NA will inevitably end up lighter than a T2. The main con is the NA tranny does give up after 200 wheel horse power. But they are easy to replace and they are really cheap and I promise you won't have to replace them any more than once every 2 months. This figure also depends on how much he is planning on driving the car. From my experience it has been worth while in weight savings. Also The GTUs is mostly so special for the fact that it comes with a clutch type lsd like GXL and some other S4 trims but it has a 4.33 rear end ratio. All other 2nd gens have a 4.10. The 5th gear is a little shorter than that of other 2nd gen NAs. The funny part is that the turbos tranny is a closer ratio unit compared to the NAs unit but the 4.33 will more than make up for that I don't want to get into this huge debate with people about why NAs are better. No matter what I say through dyno charts track records and other forms of proof, I will still be the underdog so for every NA person out there there are 20 turbo guys who will defend their cars like blind sheep. I will say this in their defense for the money and a little bit more of a headache a turbo is better. But over all a NA platform in 2 or 3 or 4 rotor configurations rule.




OH YES I AM TRYING TO SELL THESE LIGHT WEIGHT HARDCORE KOSEI WHEELS

http://cgi.ebay.com/ebaymotors/ws/eB...954524867&rd=1

rwd

turbo fo shizzle

NZConvertible

Did you completely miss the stated goals and Mark's reply? Incase you did, "250hp on a non turbo is not going to be easy, inexpensive or reliable."

The bits that make Turbos heavier either make it faster (turbo, IC, etc) or make it stay faster (stronger driveline). For a given financial investment, a turbo will always have a superior power-to-weight ratio (another stated goal) and the more money spent the bigger this advantage becomes.

Preferring NA's is fine, but you're the one making "blind sheep" arguments. Silly statements like "overall a NA platform in 2 or 3 or 4 rotor configurations rule" proves this. I don't see any NA 13B's "ruling" any racing classes where turbos are allowed.

Icemark

No, that is wrong. The GTUs came with a Viscouse LSD, not a clutch type.

Please don't post bogus info.

Bukwild

but would like to get a 250hp "bulletproof" horsepower at the crank.

Well bullet proof and rotary don't go together. Best to go with a piston engine and car for that. Not to mention you are trying to use a car that is coming up on 20 years old. It will be nothing but reliable with either turbo or NA.

bigturbo

Whats the budget for this project because if you can rebuild your engine and upgrade the cooling system on a T2 with the light mods required to make 250 then I would say go for it. Run 14 psi with a good fluidyne or koyo and a fmic setup on a fresh rebuild and you should be reliable for a while. Also the T2 tranny will handle 250 hp well. The power to weight ratio is pretty good especially if you strip out the a/c, ps, and air pump and interior with sound material. However you will spend probably 2-3 hours putting the air pump to cat system and stock exhaust system back in place to pass smog. You may want your friend to look into a first gen 240 setup with a sr or ka turbo setup. Those motor are pretty reliable at the 250 hp range but with any car he chooses, he should know that when yoru auto x-ing and dragging and beatingt he car through turns your going to lower the life of any car.

SirCygnus

iTrader: (1)

if thats the case get a starion.

RotaryEvolution

iTrader: (30)

bulletproof would be a V8 conversion but you would be sacrificing handling characterstics.

sunshine

iTrader: (3)

There is a member on the forum who has a very well modded N/A, and is only making 180ish HP. That is using a standalone, and stock ports.

I'd say that once you get into the high 180-200hp range on an N/A, then the law of diminishing returns takes over. Not much else, short of extreeme mods (pport), will make too much more hp for you.

So, get blown.

Snrub

iTrader: (1)

Forget all the BS, a TII is not as unreliable as people generally state. I think they're pretty reliable for track days. You can get to the 250hp range or at least close to it with little effort/danger. I've actually done 6+ hours on a track day with 90+ degree outside temps. I was @ ~220hp at the time with an S4 engine and I only had exhaust changes.

I hate to say this because of it could be misinterpreted to add weight to what others have said, but in terms of things need to run @ 10/10ths for a duration in the form my car was I'd recommend a rad upgrade. I think it's fair enough to say that any street car needs the same (judging by what others experiencing the same conditions were saying), so that's not some sort of unique fault of the TII. I really think you're friend would be well served by a TII, they're really well suited to what you've outlined.

As for a mod list to get 250hp, how about S5 engine, exhaust, intake, ported wastegate, FCD and maybe a S-AFC and boost controller.

ma71supraturbo

Thanks for all the replies, looks like the turbo is the hands-down winner. Budget is pretty open -- he's willing to put the project on hold to save up the necessary money. He is dead set on a 2nd generation rx7 -- we're both aware of other options, but he wants to do something neither of us have before -- work with a rotary. And both of us have '80s Supras, so we are expecting to encounter plenty of problems with a 20 year old sports car.

By reliability, I meant once you get the car dialed in, could you drive the car 200 miles to a road course, spend all day on the track, then drive home (like we now can with the supras)



So now that the t2 gets the nod, what models/years should we look for, and what are the recomended modifications.

Here's what I've come up with so far (heard from others):

'87-88 T2 with bad engine (stock clutch type lsd, cheaper purchase price, more readily available, etc) -- How hard is it to find a hardtop (no sunroof etc)?
Rebuild with 89+ rotors
Corksport or RB turbo-back exhaust (or possibly a custom made peice from 180 degree mandrel bends cut to the right angle/welded to straight pipes)
Intake
Fluidyne radiator
Greddy FMIC ($$$ -- probably just a good IC with custom piping -- and is a FMIC really necessary for this relatively modest power level? Doesn't anyone make a good overhead IC?)
Baffles for the oil pan (possibly RB oil pan or a custom cut-out welded on)
Accusump?
LW flywheel, decent sprung kevlar clutch
Some oil thermostat thing removed/bypassed?


I would hope a full exhaust, intake, and IC would gain 50hp (like it easily does on supras), but if not apparently larger fuel injectors, pump, and fuel tuning would be necessary. (Is 11.0-11.5:1 as conservative a turbo afr as it is for supras?)

Can you still get new wiring harnesses from Mazda, or are you limited to refurbishing old ones?

capn

i think i just got dumber reading that

SPiN Racing

What you end up doing is all well and good.. and welcome to the rotary world...

BUT


There are TWO words you used that scream NA to me.

DESERT

and

RACING


These two mean that at 10/10ths you are flogging the **** out of a car.. you are going to generate a LARGE amount of heat.

The Turbo is going to contribute to this GREATLY.

250 in a NA... to the wheels. YES. Bridge ported sure. Streetable? Sure.. what are you willing to put up with? Loud? Cranky at idle.. tough to drive off a light.. Etc.. (Assuming light flywheel etc) ALL these are totally managable.. to the RIGHT person.
250 to the wheels Turbo..... Easy. REAL easy. BUT... remember the extra heat.

In ITS form the N/A 2nd gen is a heat monster in Florida. You MUST run two oil coolers and a MUCH larger radiator.. to survive top level racing.

That is a STOCK MOTOR!!!!!!

Add another 100 HP and think of the extra heat.
Add desert racing.. and think of the heat!!

Now... Light factor..... TII based car... yes.. they can get lighter.. but a N/A in svelte trim will always be lighter.

Parts...
Try to buy a TII tranny from someone.. or axles.. they are HARD to get. People dont part with them easily.. They do.. and you CAN get them.. but not like N/A parts.

For me... It is a toss up.

N/A... simple. Easy to keep in top form. (Assuming stand alone EMS etc) Not nearly as much hardware under the hood to keep it breathing properly.
Power... not as great.. high elevations.. (high desert) it will suffer.
Ability to up boost for more power? Nope. When you bolt it in and tune it.. Thats it. Drive it till it breaks.

Turbo.... complex. Bit more tuning with EMS etc. More hardware. More plumbing to fail. (Water lines for turbo.. oil lines for turbo. intercooler lines)
Stronger tranny and rearend.
Heavier tranny and rearend.
Power? Greater potential.. no doubt.

Really... in a break down..
Power.. both make 250. turbo and N/A
Noise.. N/A Loud
Turbo Not.
Reliability... Tranny on Turbo slightly better.
Plumbing on Turbo less.
Tuning... N/A Easier to program in stand alone or a Weber.
Turbo easier to get more out of down the road.
Weight.. N/A hands down.
Cost.. N/A. No turbo, intercooler, wastegate, BOV, piping, oil and water cooling lines.
Upgraded RACE parts.. not parts that are FnF cool "shift mad quick yo" But are true Race parts.
Turbo specific? Umm not soo much.
N/A specific? N/A Rotaries have dominated Road racing since the early 70s. The N/A clutches and trannies are fairly interchangable.... in that the Input shaft is basically the same from early on. Want N/A related rearend parts.. or tranny rebuilds.. or flywheel.. Easy.

Basically.. if you want a Turbo cause it will make power later on greater than 250 get it. BUT.. if you will not go above 250 it is a waste of money, weight and reliability.
If Noise is an issue.. or you dont like the brapp of a Bridge ported rotary.. go Turbo.
If you are scared all the kids with TIIs will hate you for going N/A get a turbo.

Myself.. If I wanted to drive to the track and race and go home after.. I would go N/A.
The 10 Annie in my sig I used to take to track days. I ALWAYS trailered it to Sebring. It never broke on me in the year or so I flogged it.. but I could only run 2 laps at 10/10 full course Sebring before it got too hot, and I had to back off to 8/10 to keep it under control temps wise.
That was with 165 to the wheels, and a test pipe and no mufflers, boost never breaking 10.
Ny N/A sport that ended up turning into my EP car.. I could go 10/10 for a hour+ and turn faster times than the TII.. and it never got above 3/4 with the stock rad and oil cooler. It had a stand alone EMS, no cat and factory mufflers. Stock motor.

I drove it to the track. Never broke there... ran out of gas after a session when I went home without filling up ROFLMAO.. but never broke on me.

CHoice is yours.. remember.. it appears there are no rules for what you are making.. soo think of what you want out of it.. besides Desert Racing and 250 to the wheels... and make the car you want. If a Turbo is what you want.. **** MAke it!! Enjoy it.. up the boost and let it rip the N/As apart.

Remember though... If you wanna go racing in something like SCCA.. Turbo is a no-no in the main classes. Only in things like Super production are turbos cool... and you have some crazy cars there.. That will eat up almost ANY rx based car and spit it out.

NZConvertible

The ignorance in this comment is disturbing. You cannot compare a 250hp 13B to a 250hp 13BT. The turbo'd engine will make that peak power 1000-2000rpm earlier and will easily have 20-30% more power in the mid-range. A car with the turbo'd engine will be considerably faster, not to mention more driveable, quieter and more fuel efficient.

gingenhagen

You wanted a staged upgrade?

http://fc3spro.com/TECH/FM2W/power.htm
http://fc3spro.com/TECH/FM2W/sus.htm

Madrx7racer

damn where are all these newbs coming p with this ****??? jeesus...some ppl need their posting privileges revoked........I'd say sport S4 coupe with S4 TII conversion(simple to just plug and play)AVCR, SAFC, intake, free flowing exhaust, fuel mods...etc.etc.
search newbie....it's been covered

SPiN Racing

/sigh

I see from your post count I am very sorry I offended your superior posting ability.

If you read through my posts I DID mention that it will be quieter.. but then again with all the time to make 9K+ posts you must just have to skim them and post on what you like....


I will stay on the pure racing threads where you prolly wouldnt be.

NZConvertible

And my post count is relevant how? If you have an actual response to my post about power then lets have it. Otherwise please stop wasting space with childish remarks.

capn

NZ has a lot of posts because he is knowledgeable, probably more so then most of the board and the fact that hes an engineer makes his post count irrelevent to most of us. so dont dis NZ hes very knowledgeable and smarter then most of us and probably you too.