Hey guys this is my first FD so the rotary game is new to me and i need some help, I purchased a completly stock 93 R1 over a year ago and started to mod it. I have a dp, catless mid pipe, racing beat exhaust, trust intakes, apexi pfc and some reliablitly mods. The boost creeps to 14 psi when the 2nd turbo kicks in at high rpm and starts to break up. I know its most likely to due to the midpipe but what's my best option to fix this? i have done a search but all the answer's vary and honestly i dont wanna install a cat. I would highly appreciate some input! Thanks in advance.

 

1300cc secondaries, a good tune, and then safely enjoy your boost creep.

 

does that entail me upgrading the fuel rail, lines and fuel pressure regulator

 

There's tons of reading on this topic. Do some serious searching and reading.

Big thing to know here is you are very possibly on the edge of blowing a motor. You will need to do SOMETHING to remedy this.

It's a combination of having a lot of exhaust flow with little restriction, using the factory boost control, having a waste gate that's too small, and not enough fuel to support the boost that is happening.

Probably the simplest thing to start with is disabling the factory boost control. Simply unplugging the two solenoids that are bolted to the upper intake manifold should disable it, drive around and see what your boost is at that point. If it's REALLY low, that's good - you can either work with the factory system or get an aftermarket boost controller. If it's still spiking, you will need to go further - porting the wastegate, which involves removing the turbos.

If this is getting way past your abilities you aren't far from IR Performance in New Jersey, they are an excellent shop and can do whatever you need.

Dale

 

Not necessary, at least ensure having a good uprated and hardwired fuel pump AND proper tune as I wrote.

 

The can either address the creep by either having wastegate ported, or adding restriction back to your exhaust, or:

You can build in the supporting fuel, and or water injection and tuning to support the boost you’re seeing.

 

Thanks for the input guys, from what ive read the easiest and cheapest way to do this without cutting up my exhaust and adding a cat is get my stock 850cc secondaries bored out to 1300cc injectors and get a proper tune and fuel pump now i just need to sorce these injectors

 

14 psi of boost is high for the stock fuel system. Check your injector duty cycle via the PFC. As a rule of thumb we don't like to be above 85%. So if you are above that (I'd be very surprised if you are not), I suggest you stop boosting the car until you address your issue by either fixing it properly or via a band-aid.

• The proper way to fix boost creep on the stock setup is to port the wastegate. Unfortunately that means that you have to remove the turbos, but once you port it you will regain boost control.

or

• The band-aid fix. Which is to assure that you have enough fuel to support 14 psi. And you do that by:
  • Installing larger injectors which means:
    • You have to retune your PFC
    • Note that even if for some reason you choose to stay with stock injectors you should still verify to what PSI you are tuned for.
  • Installing a fuel pump to support the new demand. My preference is the denso pump over walbro (I had issues with my walbro and as it turned out I wasn't alone so I switched)
  • Addressing your ignition break up at 14 psi by:
    • Either getting an ignition amplifier such as a HKS twin power (proven to work but discontinued so you have to buy used) or a splitfire dspark max (I don't know much about these)
    • Or upgrading your coils with an IGN-1A kit (sold by sakebomb & upgrades your ignition). Unfortunately you can't use cruise control with that setup

·For 1300's you shouldn't need to swap fuel lines nor the FPT. Now as far as the fuel rail many people bore out their 850's secondaries to 1300's and its a simple swap so no need for an aftermarket rail. However, many have reported issues of the injectors sticking afterwards so I don't recommend that route (but I wanted to make you were aware of it). Now, I know that the RX7 store sells 1300's made by injectors dynamics but honestly I don't know if it requires a fuel rail so it would be best to contact the Rx7 store directly.


Edit
Oops- Apparently as I was typing away you came up with the answer. Aw well I'll just leave it here anyway

 

+3. Sometimes there can be some clutter, but a good search won't vary from this. Personally I'd just get a good hi-flow cat and call it a day.

 

I might be going that route for the time being, I have a buddy running my exact setup but using a electronic boost controller and has no issues so i might try that first. And i did alot of searching prior to posting everything was from the early 2000s and was hoping someone came up with something or 1300cc injectors that fit the stock rail without porting the stocks.

 

Don’t think a BC will do much for creep. They’re for boost spike...from the intake side.

 

Boost controller can help if the factory boost control is running away with boost. I had issues with spiking with just a downpipe/cat-back, going to an aftermarket controller or fiddling with the pill sizes can solve it.

Dale

 

i checked for the pills and i guess when the motor was rebuilt and they changed the vac lines they never put any back in.

 

To fix creep on the stock twins you have two choice AFAIK....port the wastegate or add back pressure.

 

I'm not seeing anything here to indicate boost creep. It sounds like you have a higher than desired boost level. You may be able to control this with a properly tuned pfc. If that doesnt work, then many of the other suggestions will apply. Putting a restrictor plate between your downpipe and midpipe will be the fastest, easiest, and cheapest way to get things under control. I would start with a 2 1/2 inch diameter hole, and see how it reacts.

 

You should absolutely not bore out the stock injectors. Modified stock injecotors have a very high failure rate. Either pull the turbos and port the wastegate or add a 2.5 or 2.25" restrictor plate in the exhaust. If you decide to upgrade the fuel system and tune for the extra boost, the FFE fd stepup kit with regulator and bosch/id injectors of your choice are the safest option.

 

Thanks for the input man, I am gonna try the restrictor plate to try and band aid the issue till i go with a bigger fuel system is there a write up some where on the restrictor plate ?

 

IMO If you are happy with your car's performance, just port the wastegate and call it a day. Easy and done. Because unless your tuner is on point, it would not be unheard of that you'd have issues after messing with the fuel setup. What i mean is floods easy, idle issues, problems starting, ect. That is unless you actually are looking for more power, then go right ahead

 

First question: is your fuel pump hotwired? If not, beyond 0.85 bar (c.12.5 PSI), you won't have enough fuel or injector to be that safe (you will be over 95% if your map allows that much to be used). If you are hotwired you have enough fuel and injector for about 1.03-1.1 bar (15-16 PSI) to be completely safe if your fuel tables have been setup to allow that much injector (95-100%) to support the boost.

No, you shouldn't necessarily be boosting in this instance if your tune is not designed for 14 PSI so you have to fix something.

Porting the wastegate is a weird choice that only Americans seems to do but I guess it works even though it's a royal pain in the ***. The Power FC should be more than capable of controlling boost on its own but we don't exactly know your exhaust setup and how free flowing it really is or who tuned your car and how.

A high flow cat would add the right amount of restriction to prevent the creep and you get two benefits. On twins it doesn't affect power at all as a high flow will support about 400whp before it starts to become a restriction, and even then it will be small. Second, a cat means you don't get headaches or burning eyes from the poisonous carbon monoxide.

My car, at 15 PSI on twins made 340whp with a high flow cat and a stock airbox and paper filter.

My exhaust system is as follows:

Knight Sports twin tube downpipe (3.5" internal surface area to a 3.15" collector).

RE-Amemiya 3.15" high flow cat mid pipe

Fujitsubo Legalis R 3" cat-back exhaust.

Add a high flow cat or another type of restriction and your problem will likely be solved. Or hotwire your fuel pump and update your tune for 14 PSI.

My Dyno results: https://www.rx7club.com/time-slips-d...lb-ft-1120768/

 

Thanks for all the input guys, pfc is basically on stock settings i just made 2 restrictor plates at work a 2.5 inch between the downpipe and mid-pipe and a 2 inch between the midepipe and axle back and shes holding a good 8-9 psi steady and only using 79 percent injector duty i didnt get it into 4th and 5th yet at WOT but so far so good!

 

Good to hear but it sounds like it is your tune that isn't optimised to hold the boost level you want. If you get off the base map and spend time tuning the ignition, fuel and boost setting in the PFC you will be able to control it better as the PFC does a very good job controlling boost of the sequential system.

 

Glad the restrictor plates worked for you. I should have suggested it. Oh wait, I just remembered that I was the first one to suggest that