Ok guys, I owned the car for one year and I think its time I ask for a little more of the car. Fortunately from what my mechanic tells me I don't need much to achieve my goal. When I purchased the car at 136,000 km, it had the below modifications...

Rebuilt engine with street port and 3mm apex seals
upgraded Bully clutch
Walbro 255lph fuel pump
Dual filter K&N intake with heat sheild
3" down pipe and 3" cat-back exhaust
Pettit ECU
H&R sport springs
Hawk hp plus brake pads
Apex-i turbo timer
Autometer boost gauge
Brand new tires 245/45/16
Pivot headlight controller (sleepy eye look)
strut tower brace
Brand new OEM rad 500km ago

Since then I've had the engine rebuilt again because according to my mechanic the cat was broken and choking the car. Given that I was a new owner, I had no idea that something was wrong until it started giving idling problems and smoking when cold start. I also changed the 4" canister exhaust that I had to a 2.5" recommended by my mechanic since I got pulled over for noise twice. After the rebuild I drove it down to Florida (2,000 km each way) and the engine ran great. Except after being down there for 2 months my OEM rad cracked. I took the opportunity to upgrade it since I was replacing it anyway with a Koyo Performance radiator. I also replaced the AST with an Aluminum one custom built by Fighters Garage.

I was able to get a PowerFC+Commander about a month ago from someone that bought 2 from FDNewbie here in Toronto. I then dyno'd the car and it only had 230 HP*! The cat was once again at fault but wasn't broken and the PowerFC wasn't tuned either. My mechanic put on a straight through to see if there was a difference and instantly increased power to 280 HP*. Ok so now he's going to build me a midpipe to replace the cat. Then I decided it was time to do some power upgrades. And so begins my adventure...

I had a talk with my mechanic and he said all I would need to achieve my 340-350 HP goal would be bigger injectors and a better exhaust with a full tune. He even said an intercooler is not necessary at that power level but I could get it and recommended the Greddy one. To recap this is what I have done to my car since I got it...

Done...
Rebuilt street ported engine at 141,000 km
Koyo Performance radiator at 149,000 km
Replaced Aluminum AST with a Fighters version at 149,000 km
PowerFC ECU
To do...
Racing Beat Dual-tip Cat-back
Bigger injectors
Greddy intercooler
Full tune

Mechanic suggested I move the 850cc secondary injectors to primary's and get 1000cc injectors for secondaries. Ok now here is the hard part. I am pretty much a noob when it comes to cars so I need your help in picking them for me or at least recommendations/advice.

I was looking on rx7store.net and the only 1000cc injector they had was the Bosch one. I'm assuming I need 2 of these and do you think this would be a good choice? Are there any others?

Also, I was looking at their Greddy intercoolers and noticed they have 2 types. The V Spec Core and the M Spec Core. What is the difference between the 2?

I also planned to get Racing Beat dual-tip exhaust from there. Should I also get a boost controller? What would you recommend? Would rx7store.net be the best place to order all this from? Would someone know a Canadian store I could order from with similar reasonable prices (we are at parity afterall)?

*Note: Dyno's were done with Mustang dyno and not the Dynometer dyno which gives you big numbers

thewird

 

You might want to stick with 550 primaries and go bigger on the secondaries. That may make tuning and setting the idle a bit easier. I'd keep a good quality high flow cat on there, just in case....you're still in the Socialist Republic of Toronto after all....

+1 on RB dual tip

 

Toronto can blow me, car is too low for cop to bother to check and the midpipe will look like a cat according to my mechanic anyway.

The 850cc as primaries can't be that bad can it? The mechanic suggested it himself.

thewird

 

their is one guy here local that sells greddy intercooler u can see some of hes stuff on ebay

 

What?

Your mechanic knows nothing about rotaries.

My next 'mod' would be a new mechanic.

 

^^ I agree.

 

340-350RWHP is really pushing a stock turbo RX7 to the limits (and it won't last long there). 310-320 is probably more realistic if you do most everything right. With your setup, you can probably get there with 550/1300 injectors, good exhaust system, and excellent tune. I think to get the HP numbers you are talking about you would have to push upwards of 15PSI on stock turbos which, while many have argued about it on here, isn't a good thing if you don't have $$ lying around for an engine. If you really want to move up in HP with most of the mods you have, throw on some BNR stage 3 turbos. (I may not be exact on all my thoughts here but think I'm pretty close)
PS. You may also want to add an HKS Twinpower to help out at the RPM's and load you'll hit making that HP

 

^^what he said

 

Mechanic is well known here on forums for rotaries and he's a specialized rotary mechanic. It's Dave from Mazdee's


Well, whatever 15 PSi can give me then, I'll be happy with it. I really didn't want to go single cause I like the smooth power curve and drivability of the car with twins. My mechanic said that I shouldn't get injectors bigger then 1000cc because its better they run at ~90% so the spray of gas is a clean mist.

thewird

 

The BNR stage 3's are dual (not single) just like the stock but flow better, are stronger, etc. You can maintain the sequential setup (which I did because, like you, I love the power curve) or have them converted by BNR when you order. With 15 PSI on the BNR's, pump gas, and not a particularly radical tune, you'll probably be in the 350-375 range and not over-tax everything (assuming you've done all the other mods. . .). Just a thought.

 

I think I'll keep the stock twins until they break and then I'll get the BNR stage 3's then. Do they spool the same as the stock one's?

Also, I probably need to mention, I rarely push the car full and even rarer for more then 1-2 pulls. I don't street race or anything. I'm currently running 12.5 PSi

thewird

 

leave the 550 primary injectors...and outfit the secondary rail with some 1600s
then u have all the injector u will need even if u decide to do a single turbo setup in the future.....
your horsepower goals are resonable on the stock twins (if your streetport is aggresive enough) but u will have to run them @ 14lbs of boost.......which they can handle no problem......but u definetly need to upgrade the intercooler.......
boost = horsepower in rx7s..........and u cant boost through the inadequate stock cooler.........thats what blows motors
getter tuned up and u should be there

 

You can run 340-350 rwhp for years on the stock twins without any problems, many have done it do a search.

 

^ me included. 359 rwhp @ 15 PSI dyno'ed on a Mustang dyno. stock primaries, 1300cc secondaries, larger fuel pump, street port, 99 twins, Greddy Vspec FMIC, intake, full exhaust, sequential turbos. I usually run 10-12 PSI though.


The way you are explaining things with your mechanic doesn't make him seem like the most competent. We don't know if he is competent or if you are doing a horrible job of explaining things...

I can somewhat understand someone thinking that 850 primaries with "only" slightly bored out 1000cc injectors might be more reliable. But, bored injectors are bored injectors so I think it questionable logic if one thinks that by going to larger primaries and less bored secondaries (1000cc) buys any reliability (compared to 550/1300). Its also a bitch to tune 850cc primaries... and its a bitch to install 1600 secondaries when using the stock sequential twins.

There are plenty of mid pipes readily available for $50 or so fwiw.

i've also run with a cat and while i did melt it (due to various reasons), that would in no way required me to replace my motor... Either you are misquoting your mechanic or something awful happened.

Another thing that is odd is the fact that you dyno'ed such low numbers make me question the tuning and overall prep / mechanical condition of the car. At 13 psi (compared to your 12.5 PSI) with the above mods, I dyno'ed 330 RWHP on a Dynojet. The Mustand dyno reads lower but a 50 HP loss can't be blamed on difference in dyno manufacturers alone. There seems to be something else going on with your car.


I mostly agree with your mechanic's suggestions for reaching your numbers in the way that you explained them... To reach those numbers it seems the only thing you really need are 1300cc secondaries, a 3" exhaust (like the nice quiet Racing Beat that I have) and a decent intercooler. I'd honestly skip the FMIC and do a stock mount if you aren't pushing the car much. I would consider the IC very important when running over 10 PSI. Its not designed to flow much more than that so you'll be making the turbos work harder.

Good luck.

 

850X4 would be cheaper and would provide enough fuel to support 15psi on stock twins with all bolt ons, I ran a similar set-up for a few years on a proper tune via PFC. I think I paid 100 for the injectors and 50 for the work done to modify the factory rail.

either way will work, 850X4 is just cheaper.

 

[QUOTE=thewird;7387886
Since then I've had the engine rebuilt again because according to my mechanic the cat was broken and choking the car. Given that I was a new owner, I had no idea that something was wrong until it started giving idling problems and smoking when cold start.

Help me to understand: You had your engine rebuilt because the cat (catalitic (SP) converter) was broken?? What does "broken" mean and what was the broken cat doing to your engine that would require a rebuild?? Why not just replace the cat??

My gut reaction is that your mechanic took advantage of you because, as you said, you were a new owner.


Respectfully,
Super77

 

The car was running pretty horrible by the time I took it there. It's true, I'm probably not explaining the situation the best. There was also an electrical problem with the injectors since primaries and secondaries were working at the same time and the car was running super rich. It was backfiring like a beast, and again I thought that was normal for rotaries >_>.


As for the cat, the way he explained it to be it was broken in such a way that the metal would move and block the airflow almost entirely. By the time I brought it to him check engine lights were coming on and the car was in really bad shape. There might have been other things but that's what I remember.

thewird

 

[QUOTE=Super77;7389068][QUOTE=thewird;7387886
Since then I've had the engine rebuilt again because according to my mechanic the cat was broken and choking the car. Given that I was a new owner, I had no idea that something was wrong until it started giving idling problems and smoking when cold start.

Help me to understand: You had your engine rebuilt because the cat (catalitic (SP) converter) was broken?? What does "broken" mean and what was the broken cat doing to your engine that would require a rebuild?? Why not just replace the cat??

My gut reaction is that your mechanic took advantage of you because, as you said, you were a new owner.


Respectfully,
Super77[/QUOTE]

+1

a broken cat = rebuild ??? wtf

 

I ran 16lbs on the stock turbos and stock fuel system, with a fuel computer for 3 months, and ran strong, untill i blew my motor,due to doing a left hand U turn with a low tank of gas and accelerating hard thru the turn. I would look into a fuel surge cover. Or never let your car go under 5/8 of a tank. There's info on here about 93-94 rx7 have fuel starviation with a tank of 5/8 or less,and doing a hard left hand turn. Never new about it till lately.

 

Just leave the rebuild alone lol. I'm looking to the future, not the past. I think I'll go with the 850cc/1000c setup and if he can't get it to idle properly, then I'll try one of the other recommendations 550cc/1200cc or something near there.

thewird

 

lol srry, it caught my eye when i read your first post. The Power FC should be able to handle any injectors you throw in there.

 

I went with 4x850, and I personally love the setup. I've heard a few horror stories about the 1300s failing, and I didn't want to take a chance. When I was asking someone with 1680s if I should put them in the secondaries, they told me that there was a slight hesitation, and that it was way overkill for the numbers I was looking to make.

I think what you should look to purchase are the mods that I am running, plus maybe a twin power or something. After much research, I personally believe I have one of the greatest setups for the numbers I am trying to run; and with a streetport, you should definitely hit your mark.

~A-Rod

 

I was wondering about the Greddy FMIC (V Spec Core). It said its front mount which means it won't just be replacing the stock intercooler right? Would installing it be a simple job or would work need to be done to make it fit? It says I need the Greddy elbow, do I need anything else and where do I get that?

thewird

 

A front mount will eliminate the stock intercooler. I believe the greddy front mounts require you to hack up the bumper a bit. If it says it comes with all piping, then yes you will need the Greddy elbow... unless you want to fabricate a pipe to fit with your stock one.

 

I'm replacing the stock bumper with the 99spec one when I finally get it from FDnewbie. Would it make a difference if I install it now vs. later?

thewird