7THSIGN

Hello everyone. My cousin owns a 93 RX7 and him and I both now that you can not just start adding parts to the car without proper steps. Only modifications done to the car thus far are:
Apexi Intake
HKS Downpipe
HKS Exhaust
Defi Boost Gauge

He is now looking to add a Power FC and tune with the following modifications:

Removal of cats and straight pipe added.
Front mount intercooler

Even though he is not raising boost, I know the removal of the cats and the addition to the larger intercooler and hard pipes that boost will rise. So I advised him to purchase a boost controller.

Are him and I missing anything, or modifying the car incorrectly? Have others done these modifications and the car ran properly? Also, we will be having a very experienced RX7 tuner to tune the car (Ray from PF) but I was curious to know how many RX7 owners have had bad luck on dyno tuning? Thanks you in advance.

c00lduke

Your off to a good start. During everythnig you might want to look into upgrading the AST and radiator due to the plastic parts becoming brittle after years of heating and cooling. Ray should be able to help you without any trouble.

Harold93

you should also look into redoing you vacume lines, they will be brittle and starting to crack if you do get vacume leaks you will start having small problems right away but they can compound into other things. the bosst controller is a good idea and a power fc is a great point to be at you can upgrade alot more once you have that in there . be carefull with your settings and good luck

dgeesaman

iTrader: (7)

While the boost controller will be important to avoid boost spiking, you will also face boost creep. Either porting the wastegate or adding restriction is necessary.

willjs7

iTrader: (1)

get some sort of an ecu, definatly get a good boost controller, and tune acordingly to afr's and fuel support, make sure the car is running flawlessly, b/c the more mods present the more trouble you can run into if things arent in tip top shape

7THSIGN

thanks guys, my cousin had a full hose job done to the car when he purchased it. so thats a check off.

hus

Hey Dave,

Is porting the wastegate or adding restriction only necessary because he is planning on removing the cat? In other words if I were doing the same setup with what he listed above but with a HKS downpipe and RB catback is there any other restriction that should be added? And if so what? Thanks -Brad

dgeesaman

iTrader: (7)

Leaving in the main cat keeps enough restriction to avoid boost creep (and wastegate porting). Apparently a normal high-flow cat will usually not creep, but the metallic substrate cats flow enough to see it in some cases.

Still, with a dp and cb it's possible to get some spiking depending on the car, intake, etc. If you get spikes a boost controller will solve it.

Dave

Narfle

iTrader: (16)

Get a restrictor plate if you must use a midpipe. 2 1/4" seems to do it pretty well. Now the midpipe is almost pointless. Or keep the cat or pop your motors. Whichever.

FDNewbie

iTrader: (10)

7THSIGN, a few things:

1) With the freeflow exhaust (intake, dp, mp, and exhaust) and IC, you'll easily be seeing 12 - 13 psi on the stock ECU at WOT, but the stock ECU won't be able to compensate for the added boost. You'll definitely need the PFC and to have it tuned. So make sure you stay off the throttle (ie no WOT runs) until the car is fully tuned FOR the additional boost levels you'll be immediately seeing.

2) Please make sure he's getting a FMIC for the right reasons. If he's going to be drag racing, the FMIC is great. But (and my guess is) if he's just going to be roadracing and even occassionally experiencing NoVa's horrid stop-and-go traffic, I'd *strongly* advise AGAINST a FMIC. A FMIC, by design sits in front of the radiator, allowing the radiator to heatsoak *much* more quickly than a SMIC or a V-Mount. That's why FMICs are optimal for short bursts (ie drag racing), but NOT stop-and-go conditions (driving around town) or extended use (road racing). I'd stick w/ a SMIC, say a PFS, or if you'd like larger, an M2 Medium or Large SMIC. Or, if you've got the cash, I'd spring for Chuck's (RotaryExtreme) V-Mount setup, which comes with the radiator as well SMICs and V-Mounts will net lower water temps (ie a cooler engine) overall b/c the radiator won't be so prone to heatsoaking (as quickly).

3) You're getting a PFC. Good move. BUT, the PFC is NOT known for being the greatest boost controller. It's good for SETTING boost, but not HOLDING it. Like others have said, once you take off that cat and go w/ a MP, you'll see LOTS more power, but also open the door to BOTH boost creep and boost spike. A good electronic boost controller like the old Greddy Profec B or the newer Greddy Profec Type S will do the trick for spike. For creep, as Dave said, the ONLY solution is to port the wastegate. The restriction Dave and Barban mentioned as the other "solution" isn't really a solution, b/c it negates the entire point of the mp IMO. You might as well stick w/ a high flow cat then But on that note, don't worry about creep UNTIL you notice that you have it. Many FD owners experience creep w/ mp's, but some do not. So don't fix it if it ain't broke

4) If you're not going to be raising the boost, IMO, you're wasting your money That car will run just fine at 12 or 13 psi, fully tuned, on the stock fuel system. That's the limit, but it'll do it w/o any problems. If you're gonna get a tune for the PFC, you might as well tune for the correct settings while you're at it. Also, keep in mind that the PFC holds/stores TWO boost settings (and hence two fuel maps). So you can have Ray set you at the stock 10 psi (or say, 11 psi) for one, and use the other setting for a tune at 13 psi. That's what I had my FD at. For everyday driving and cruising, keep the map on 10 psi. Then when you wanna get on it, reach over, and in about 3 seconds - and in REAL TIME, ie while you're driving! - you can be ready for 13 psi

5) Ray will do a great job dyno tuning your FD. Having said that, it's very hard to find optimal conditions in a building w/ just a fan and on a dyno. There's no substitute for WOT tuning (ie on the road) IMO, although it can prob. land you a ticket or two lol. But I only say that b/c you asked

Please be careful with the advice you give. Doing a hose job when it is not necessary can cause MORE harm than good. The original hoses are indeed brittle, but when left undisturbed, they're pretty much melted on and will usually give little trouble at all. A newer hose is actually MORE likely to pop off and give you the biggest headache trying to find the vacuum leak b/c it's seal is no match for the original melted on hoses Hose jobs should be reserved only when you know for sure that your original hoses are in VERY bad shape, and/or when you're already pulling off the turbos/dropping the motor.

~Ramy

adamtassell

Please post the results of your tuning. I would like to know how much power those mods will make. Thanks in advance.

7THSIGN

thank you al for your great feedback and help.

FDNewbie, how you been buddy. did you get the car back from TX? and thanks for all the info.

I think we might just do a high flow cat instead of straight pipe.

I will definitely share the results and dyno graph with you guys!

hus

Thanks.

FDNewbie

iTrader: (10)

I'm good man...crazy busy. And na, my car's gonna be in Texas for a few months... But it'll be worth the wait when it gets back

Prob a smarter idea, although it won't be as fast (or fun hehe)

~Ramy

Brent 94

iTrader: (1)

I still have the high flow on my car and i haven't ever experienced boost creep or spike. Lemme know what he hits on the dyno, i have basically the same bolt ons and i'm making 303rwhp. Hope all goes well.

Brent

7THSIGN

I bet it will be a monster when you get it back!

My cousin and I talked about removing the cat or adding a high flow today, I know removing it for a straight pipe would net more power gains, but we don’t want to risk 8hp more for a blown motor. But we will see what Ray recommends.

FDNewbie

iTrader: (10)

Oh you can count on it. Someone's still a little sore from a run a few months ago...

It's not a grave-digger, but it does make your car less reliable in the sense that it makes you more likely to creep and spike, both of which cause you to run lean and can result in a blown motor.

There are probably hundreds of FDs running around w/ midpipes on, mine included, and I wouldn't have it any other way. I assure you it's a LOT more than 8hp...dollar for dollar, a MP will prob net you more hp and "butt dyno" points than ANY other mod. It's amazing. But you just gotta make sure you run it safely. If you do so, it's awesome. But also keep in mind you're in VA. I hope you guys either plan on keeping the stock cat and will just swap it in for emissions testing, OR you have a hookup that'll pass you...

~Ramy

revsteve

iTrader: (6)

Back to life -

Im running DP & CB as the only airflow mods to my engine and see a bit of creep to 12psi.

Is porting the wastegate the only thing to do (Since I have my stock cat in and it doesnt seem to be enough restriction)?

Regulator716

hey fdnewbie... im in the same situation as 7th sign except for the intake on my car.. im a real newbie to the fd world and need some help on making my car reliable and fast for daily in town driving.. what mods can you reccomend? i work with a few rotary heads and they're tellin me i need a front mount.. aluminum radiator and a power fc? what do you think?

thanks..

FDNewbie

iTrader: (10)

Steve, you have stock twins. You're not porting jack. The stock twins have internal wastegates. You simply need a boost controller. Oh and 12 - 13 psi is the upper limit of the stock fuel system FYI.

Regulator716, welcome to the forum! You're in the right place to learn about the FD... and oh is there much to learn

First off, read the FAQs at the top of the 3rd Gen section (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/). There is a LOT of info there. I'd also read this thread to know how NOT to wreck your FD in the first 2 weeks https://www.rx7club.com/interior-exterior-audio-26/throwing-cost-out-window-468485/. It doesn't matter what you've driven in the past; the FD is a *completely* diff animal, and is VERY easy to get sideways or even spun out completely - the results of which are not exactly pretty

As for your FD, under the FAQ section, you'll see the "Reliability Mods." Do them. Esp. the ones in these two posts:

1) https://www.rx7club.com/showpost.php...03&postcount=6

2) https://www.rx7club.com/showpost.php...59&postcount=2

The only warnings about the above two posts I'd say are

a) Like I said, leave the turbo hoses as is if they're fine, and you don't have a boost leak. They're brittle and old, yes. But they're also melted on. They won't be going anywhere. Once you disturb one, it's a mess, and you gotta do ALL of 'em...and they tend to pop back off unless you REALLY ziptie 'em down hard.

b) The first post is from '01. We've come a long way in terms of fuel and ECUs. So you don't need fuel computers (AVCRs and the such). The Power FC is a complete stand-alone, plug and play, and allows you to make changes in real time. You'll still need the upgraded fuel pump (Supra TT Fuel pump is drop-in) and possibly injectors etc, but all that can still be controlled from the PFC.

We also don't use AFR gauges anymore either, unless they're hooked up to a wideband. And for ignition amps, if/when you need it (when you're heavily modified and are getting ignition breakup up top), the current unit of choice is the HKS Twin Power Ignition Amp.

Lastly, as I mentioned in my earlier post in this thread, unless you're gonna drag the car, stay away from a FMIC. Not only is there a pressure drop from the extra long piping, but you're also gonna increase the likelihood of (and how fast) heatsoaking the radiator. A large stock mount IC (SMIC) will be more than fine, or a V-mount if you got the cash. Now if you ARE going to drag race the car, I'm sorry, cuz you bought the wrong car. Expect to drop well over $20K into the car, and prob another $10K along the way to replace the misc driveline components you will continually be breaking

~Ramy

PS: If I can help ya get these parts at discounted prices, lemme know. Just drop me a PM

Regulator716

thanks for the info.. FDnewbie.. there will be no drag racing this car for me.. it will be babied and only driven once a week at most.. i just want to make it reliable and fun to drive when i take it out.. thanks again..

dgeesaman

iTrader: (7)

With those mods, what you're seeing is a boost increase, but not boost creep. Boost creep will never happen with a stock cat.

A boost controller will dial that 12psi down to 10psi again. While the 12psi you're seeing now is probably not going to blow the motor, your AFRs are running leaner. Getting it under 11psi is probably a very good idea.

Also make sure your boost gauge is stopping at zero. It's common for cheap boost gauges to lose zero and always read a little high or low.

Dave

FDNewbie

iTrader: (10)

My pleasure

I kinda overlooked that fact hehe

scrubolio

iTrader: (8)

wow, one of the threads ever, thanks FDnewbie

FDNewbie

iTrader: (10)

(and Dave)