Heland

Hi Guy's,

First of all - Great Forum! You guy's definitely know you stuff!

I was hoping that you could answer a question or two for a Rex newbie.

I am looking to put a small shot of Nitrous on my FD. After searching the Internet over the last couple of months, I have found that:
1, Not many FD owners have Nitrous installed
2, Many people that have tried Nitrous, have blown their engines!

I suppose my first question is - Is there a safe way to install Nitrous on a FD3S Twin Turbo with additional Mods? I'm only after a 35 or 50 shot.

My friend has sold me a Cold Fusion Wet Nitrous Kit very cheap - and I would like to use it without blowing my engine.

My Car has the following engine Mods:
1, HKS Induction Kit / HKS alloy intercooler pipes
2, Apexi FC ECU with controller
3, Uprated rear exhaust section
4, Uprated ignition leads

Any Help / Advice would be appreciated.

Also - The Engine overheat (or at least I think this is what it is) warning flickers on intermittantly from time to time when accelerating. Anyone know if this is anything to worry about? The Water temps are around 88-90 Degrees C & Intake Air Temps are around 38 Degrees C.

Thanks,
Andy

51st State

skunks

well what you gotta sak yourself is do you want to spend upwards of 500bucks for soemthing you can do/get the same results by just raising boost and/or by just buying an intercooler? sell it and make a profit and then use the money towards something else. perhpas save it for a rainy day...

dont forget that you will have to refill that badboy and its not that cheap (for me it cost upwards of 45dollars per 10lb refill...)

BTW: i would think it would be safe as long as you took the necessary precautions for it

apex_sideway

Before you do anything get a downpipe, radiator, and ast. . . . I don't know about NAAAWWWS though; have you done a search?

finnicky7

I hate to be the bearer of bad news but...With your listed mods nitrious is the last thing you need or want. Build an Rx-7 for reliability above all else. Fuel, Air, Suspension. These are key areas you can always build on. Nitrious is waste of time until you car is at the highest level of perfection. IMOP I would reccomend selling the kit and taking the cash and get some more uprgades. This is all just my opinion, but being that this is your first post beware flaming may occur.

Heland

I only listed the current engine MODs.

I think I have the suspension sorted (Ohlins all round lowered).

What sort of Fuel/Air MODs do you recommend?

Thanks, Andy

finnicky7

Well, do you have a upgraded fuel pump? How about secondaries and FPR. A front mount intercooler is great upgrade as well.

Heland

Hi,

Although I know the principals of a Wankle Engine - I'm very new to the world of Rex's - Please be patient with me :-)

My car has a Mazdaspeed Bodykit - me thinks that a HKS intercooler is fitted, but is not getting much airflow as it is monted high behind most of the front nose of the car. Should I change the front end?

As for fuel pump - No, I believe it is stock. Which one do you suggest? Perferably one which I can get in the UK.

Okay - lets turn this thred around a bit. I have £15000 bucks to spend. I want a reliable car - but one with a lot of fun on track days. What Do you suggest I buy?

Here is a full description of the car (just imported it from Japan):

1994 (October) RX-7 Type R2. 5 Speed Manual. 71,747km (44.591 miles) from new. Usual RX-7 Spec includes: Air Conditioning, ABS, 4 Piston front callipers, fully independent suspension will double alloy wishbones, Power Steering, Power Windows, Remote Controlled Door Mirrors, Central Locking. This has been a non-smoker's car. Fitted mats are also included...all the standard spec. Interior. Note that the R2 doesn't have the back seat (not useful anyway), but lightweight storage bins and a plastic (removable) upright section seperating this section to the rear. R2's are particularly sought after by taller RX-7 drivers, because they allow extra seat travel (After modification to the runners).

Improvements: Apexi FC ECU with controller currently set to 0.9 Bar maximum boost - this is the best ECU available for use with UK fuels and is the unit RX-7 tuners in the UK most favour. Ohlins Suspension struts with 30mm lowered and uprated springs, HKS induction kit, HKS alloy intercooler pipes (Standard ones tend to pop off with increased boost), uprated rear exhaust section, uprated ignition leads, Hasemi 17" 2 piece alloy wheels shod with 255/40/ZR17 & 235/40/ZR17 Bridgestone Grid II sports tyres in good condition. These modifications combined should give around 335 bhp at 0.9 Bar boost. Suspension struts are exactly the same as fitted to our own RX-7 so it's a system we know well. Not harsh, but a bit harder than standard, yet affording good progressive handling to enable the car to be slid with confidence when desired. Note that in the boot is also the original suspension, as well as original ignition leads.

Inside, there's a Momo "Race" Sports Steering wheel and a Sony MD/CD/Radio unit of good quality. On the dashboard are Greddy Oil Temp, Water Temp and boost gauges (Stuck to the dash with double sided tape only - these need fitting more tidily). In the rear there's an uprated strut brace, complete with rings for mounting the uprated seat harness for the driver (Original seatbelt is also still fitted).

On the outside, there is a Mazdaspeed front bumper with Endurance race style driving lights integrated into the front bumper. Original option Mazda side skirts are also fitted. The rear spoiler on this car has been removed - or was never fitted. This gave us the opportunity to fit a low mount Auto-Exe item (High Quality) with adjustable foil. (Picture is available).

We have test driven this car and can report it goes very well indeed, just like a good one is meant to. 2nd turbo from 4,500 RPM is around 350 bhp's worth of (A lot of) fun.

The interior is in good condition, with standard seats fitted. Fabric is in good condition, with no faults to report. Note that there is also a knee bolster fitted, which helps give further support at high cornering speeds. The cost of wheels, ECU, exhaust, gauges, Mazdaspeed front, etc, is around £5,000 total in Japan. Mostly RX-7's with spec like this and genuinely low mileage are too hard to find at affordable prices.

Regards, Andy

SlingShotRX7

Good luck getting any kind of Info about Nitrous on your FD.

I have asked years ago, and several others..
The topic is tabboo... Because people are narrow minded and have this
" nitrous is bad concept " or just dont know.


Even if you were to have all the suporting mods..
You'll still won't get any answers. Either the ones that know, don't want to share.

Ironic thing is, that over in Japan.
Alot/many/if all the Tuners and etc.. Spray their FD's with Nitrous.
Like Rmagic, RE, and other big timer in Japan and private owners like us.

I guess here the Aspec FD owners scared to boost + no2. who knows.

ljrotary

Here are a couple of links with info about nitrous on an FD.

http://robrobinette.com/nitrous_install.htm

http://www.scuderiaciriani.com/rx7/N2O.html

speeddemon7

from what ive read about nitrous on an fd is that it doesnt exactly work well for our engines.This was in turbo magazines.
I remember reading that the apex seals dont exactly respond well to sudden heat shocking which is what nitrous is.But I think it applied only to the ceramic apex seals.Of course I may be wrong.Gimme a little time and ill dig up the actual magazine and get back to you for sure.

Heland

SlingShot, Thanks for the info!
If you search the Internet enough (as I have over the last few months) you will find many failed Nitrous installations. The annoying thing is that none of them tell us what broke (just BLEW THE ENGINE).

My feeling is that If Nitrous does not work well with a Rotary, then there must be a reason.

If the Apex seals can't stand up to the sudden temp drop - That can be fixed! i.e Don't use the ceramic types.

If the Engine failure was due to not enough fuel getting through under Nitrous, then we can overcome that as well.......... I COULD GO ON ALL DAY TALKING ABOUT POSSIBLE PROBELMS AND THEIR FIXES.

When Mazda set out to develop the 13B, they had lots of failure and design problems. In a way - they are at a disadvantage as they only have a limited amount of data and skilled engineers working for them - With the internet, we have access to thousands of engineers, some of which have tried Nitrous installations. SO COME ON GUY's IN THE INTERESTS OF SCIENCE - lets fix this taboo and find out what we need to do to make Nitrous safe on our Rex's.

P.S. My Rex will need a engine re-build in the next 10000 miles, so if I'm go'in to experiment - why not do it now........................ :-)

SlingShotRX7

Good luck..

It maybe true that our Rotories may not like Nitrous, and ETC..
BUT its being done and being done by many.. Especially over seas.

The funny thing is.. That some people on this forum use Nitrous.
hate to throw out names, but " ray wilson" @PFS sprays.. and has
a 9/10 second FD. But do we get any tips or advice?? nope..

I searched the internet.. Went to Rob's site, and Lightening in world of thunder and etc.
They do tell how to install and etc. BUT thats about it..
NO advice no tips no nothing..

It would be great if someone out there could tell us.. Or Recommend
How much of N02 shot would be good, How to Tune for it and etc..
BUT its everyone's secret...

I Guess the oens that have N02, blew so many motors to do it right.
I guess they are bitter and do'nt want to share the knowledge.

couple of years ago. I wanted to do a lil shot of N02.. GOT no support
what so ever...

Now I am T78 single, and I wouldn't mind still getting a LIL shot of N02.
For those times, when I feel that I may lose a Race...

and for t hose times at the track.. OUr FD's being Modded. are placed in catagories
that have built up Supras, Vettes, and other HP cars with BIG TURBO's +plus
They have N02.

Its a sinking feeling lining up next to a BUILT supra with BIG as TURBO and Hearing him
PURGE their NO2, in staging... I would just like to even the playing field

finnicky7

Read this : https://www.rx7club.com/2nd-generation-specific-1986-1992-17/nitrous-oxide-injection-rotary-111605/

93BlackFD

i personally do not like the idea of having a apex seal at 200-250F+ and then spraying -40F nitrous on it

can we say brittle?

luizajeff

Consider something else here, air flow is everything to a rotary engine so replace the down pipe and get a larger IC, (stock or front depending ont he HP you're after) and set it up with an IC sprayer. This will cool the charged air, increase power, and won't be as hard on the system as a shot of NO. Otherwise, max air flow through the entire system will give you more power and acceleration over all. (A fuel press. gauge would be addvised however in either case).

FDreaming

The way I see it the apex seals are just about as vunerable as the piston rings in a *gasp* Otto stroke engine. In a combustion chamber there is a thin layer of non-burning air/fuel that "protects" the metal it reduces the temps that the metal is exposed to. If the metal of our housings were exposed to 1500+ degree temps over and over it would melt, the temp changes in the area of the apex seal are not going to be that drastic. I may run an N/A FC but I've done my fair share of research on when Nitrous blows up rotaries and why. The fact of the matter is here in the U.S. most N/A guys running the spray are having little problems at all. Stone stock motors are sucking up 75shot without flinching with just a standard wet kit and maybe a 255lph pump and a FPR. The guys I could find that blew their motors overboosted like crazy on the bottle. When nitrous is injected into a motor the volume of ait coming out is increase exponentially. If your running a stock wastegate it's not going to keep up. Guys in TIIs have stock gates ported out as big as possible with 35mm(don't quote me on that, whatever the biggest one you can fit in a stock WG) flappers and they still boost creep a little on 35shots.

If you have all the right parts to back it up there is not a doubt in my mind nitrous can be run in copeous quantities on FDs with "normal" wear and tear. make sure you have the compressor bypass valves capable of flowing the extra air, fuel, fuel, fuel!!! don't even think about using a dry kit, and get the thing on a dyno when your tuning it with datalogging on your boostlevels so you'll know if it spikes when it activates and you can addapt, etc. etc.

Back to the sudden cooling issue, mount the spray nozzle a little ways down from the TB like a foot or so, you can go 6-16 inches put it further out so there is time for the high intake temps to blend with the low nitrous temps and settle out before it hits the combustion chamber. It depends on the size of the motor/shot and all that but the most I've ever seen intake temps drop with nitrous is Maybe 50% and that was HUGE shot on a drag mustang.

Anyway, it can be done, and if someone would just give me an FD I'd prove it or you guys can just wait till I finish up school(4 years left!), then we'll see what a 13B can handle.

Edit: I ran a 75 shot on my Honda Prelude for a few months, I drove it to the track, ran low 13s in a FWD car on street tires, and drove home 5 bottles later it compression tested perfectly across all four cylinders(we were going Wet and looking at a 125 shot, so we did some testing) unfortunatly that was the night before my car was stolen, now I'm putting together a small setup for my FC 86' GXL. If you guys have any questions nitrous wise I know a little about it. Feel free to PM or E-mail me.

Heland

Carusot,

I have read that thread on some other forum. Good all-round advice, but does not help me :-(

Nitrous on a turbo: don’t do it if you need to ask. Even with a massively ported S5 wastegate, you’ll still experience crazy boost creep. Sorry to sound rude, but blown motors are already a prob for these things.

I tried to mail him to find out how much n2o he was trying and also if he had a decent ecu that could regulate the boost - but no answer. I suppose that the original thread was a while ago - so he may have changed email address.

luizajeff,
Cooling the IC I think is a good idea, please forgive my ignorance - but I imagine that you would do this with co2 rather than n2o. If this is the case, would I be able to fill my n2o with co2?

Heland

FDreaming,

Thanks for the info, just one question though............

If I mount the "Wet" spray nozzle that far down - do you think I'd run a higher chance of pre-detonation? i.e. To cause a fire or combustion you need three things:
1, Oxygen
2, Fuel
3, Ignition

The Wet spray will give the first two - will the heat of the engine (if its given longer to heat up) provide the ignition and cause detonation before the mixture reaches the rotors?

WHIPSrx7

I don't think there is nearly enough heat before the engine to do that. i.e. The water temp is only (at max on a reliable car) 90 or 91 degrees Celsius.

Kento

Your intake tract would have to glowing red hot for that to happen.

"Pre-detonation"? No offense, but it appears you need to do a bit more research on internal combustion engines.

Heland

Sorry Kento,

"Bad use of words".

Would it be okay to use a n20 bottle for co2? And would Co2 be perfered over N2o for cooling the intakes - or is it just a cost issue with n2o being more expensive?

Kento

They are basically both gases that have been compressed into liquid form in the bottle, so the difference in their cooling properties is minimal.

austinsFD

nos? why not big *** turbo dude?

c00lduke

Why not both?

Enconsiderate

I am not one to advocate NO2, but I can see the reason why people would choose a Wet NO2 sys over a "big *** turbo", it can be summed up in two words... LAG & COST.

Now i know what your gonna say "tunning", right? with a ported motor, proper exhaust, intercooler, fuel upgrade and ecu, lag can be delt with. But what people are looking for is instant HP and at a minimal cost.

Now what is out there that will give you a good amount of INSTANT HP at a minimal cost... hmmmm... oh I got it NO2

I know its not safe to put that much strain on the motor with a stock ecu, but with a chipped ecu and upgraded fuel pump you got yourself a good reason to try a WET NO2 sys.

Do the math in your head ~$700 for a wet NO2 sys (not to mention the upgraded ecu $400, and new fuel pump $200) or ("cheap way") upgrade to a FMIC on a stock turbo set up and run at least $1000 for the IC, not to mention the fuel mods (injectors, fuel pump), ecu (programmable preferd to tune properly), new piping, port the waste gate, and get a boost controller to turn up/ controll the new amt of boost.


I am not trying to say I would get it. (actually i don't think i would ever run NO2), but I am trying to say its an underestandable choice. I do hope more people try it, do write ups, explain their failures, or success. Maybe it will convince me or you to try it too.