TwinCharged RX7

iTrader: (14)

I've been doing some searching and I'm not having much luck deciding on what to do with the fuel system, when I got my car it was making 375whp, now that its going down for the winter and I've got a new streetported engine, i want to see if I can make 500whp next spring. Here's what I've got, and I know the fuel supply is holding me back, but if you see something else, pleeease let me know.

Also, what psi do i need to run to do this on my setup? I am staying with pump gas only, and no meth injection, so the amount of boost that i can safely run may severely limit me.

full 3" exhaust
Pineapple streetport engine, dowel pinned, cooling mods.
Greddy T78 turbo
PF Supercars SMIC - the big one
TEC GT ems with full ignition system upgrade
6puck sprung ceramic clutch from Competition Clutch
SR Motorsports 11 lb flywheel

FUEL:
Walbro 255 - I'm pretty sure I'll either need to switch to a twin pump setup or get a supra pump (denso)

Injectors - 550 prim. 1300 sec.(enlarged stockers)
1. Can I do the secondary mod and move the 1300s to primary(like what you would do when moving the 800's to primary) or will this be too much, the TEC GT system is pretty advanced so i think it might idle alright with some work, or I could trade with someone for their stock secondaries and use them instead. ANY RECOMMENDATIONS?

2. Secondaries- do I need 1680's and if so, will they plug in to my harness, i'm not sure about resistors, if i have the TEC system can it compensate so no injectors are needed?

3. fuel lines, can i stick with what I've got for lines? i think stock

4. FPR - at what point is one needed? it doesn't have one at this point.

thanks in advance

arghx

iTrader: (3)

First of all, 500whp on pump gas with no meth and a 'streetable' (whatever that means) turbo is probably asking too much if you care about engine life.

Second... you are going to need 850/1680 at least, and when you get a new secondary rail you should get an FPR. Many people would tell you to go with dual fuel pumps as well, although that kind of power has been done with a single pump before. Technically you COULD put 1300's in the primary slot and got 4x1300. I'm sure the TEC3 is better with big primaries than say the Power FC, but you are going to create a headache for yourself.

dregg100

iTrader: (34)

put a denso pump in there as walbros are prone to failing. also get rid of those bored out secondaries as they are prone to failing(sticking open or shut) you could try 550 primaries with the stock primary rail and 1680 secondaries, but that would be pushing it. 720s or 850s would be best primary. by the way, you do have an FPR already, its just not adjustable. lol

as mentioned above 500 on pump with no extras is pushing it, but it has been done. based on your post i would say you are pretty new to this and would not try it on pump alone.

i would say:

-supra pump hot wired
-850 primary and 1680 secondary with top feed rail
-aeromotive FPR
-some sort of AI

that should do the trick

TwinCharged RX7

iTrader: (14)

you're right, I am a bit new, but I appreciate the input, I hope it showed that I did search for a while before posting.

The reason for not wanting to use meth or water injection is that I've seen the system fail before, and when tuned specifically for high hp levels using injection and it fails, you are done for. So maybe my goal of 500 is a little high for the level of risk i want to take.

It looks like I need 1680 secondaries no matter what. if i tone it down a bit and aim for a minimum of 450 whp, are 550 primaries still fine?

am i correct in thinking that i need an fpr because i would be switching to a different rail for the bigger secondaries?

one of the main reasons for this is that my roomates T78 just came in the mail for his MIV supra. His fuel system is good for 550 whp, and i can't be letting him have the faster car. I know i'm lighter, but the power curve is completely different, and the weight difference advantage decreases at high speeds (highway pulls), so i need to up the power this winter.

dregg100

iTrader: (34)

then just do water injection. its not a fuel. but saying it fails is like everthing else, its only a machine. your walbro is way more prone to failing than an meth setup. if it gives out in boost, your done.

TwinCharged RX7

iTrader: (14)

I see your point. I'll start doing a little more research on injection systems.

but are 550 primaries fine as long as my secondaries are adequate?

OneRotor

iTrader: (3)

this was answered above....720's or 850's for 500whp.

dregg100

iTrader: (34)

it may be possible depending on the tune, but why risk it? you would be running high duty cycles and risk of, yup, injector failure. just spend the extra couple hundred and do it right. then you also have room to grow.

oo7arkman

iTrader: (2)

Exactly, do it correctly the FIRST TIME. And in all honesty, to beat a 550whp supra I think you should be fine around the 450whp mark to accomplish that. A 500whp FD is quite a different animal than most other cars with 500whp.

Dudemaaanownsanrx7

iTrader: (23)

If you did decide to go meth injection you could probably get it done with the 550/1680 setup as you will be removing alot of the fuel from the map. I think around 40%. Howard Coleman has some good posts in the AI section, and if you have a good system with fail safes you'll be safer then if you try to push 500 hp on pump gas and the PSI levels you'll need to get there without AI.

Also water injection adds more reliability, but doesnt allow you to increase the boost like meth inj. You also lose a little bit of power unless you lean out the mixture a bit. But you won't get to 500 hp with just this.

Another alternative is to go for 425-450hp, which is doable with the right turbo and around 16psi on a street ported engine. Go with something like a gt40.
Then tune a higher map for 20 psi on race fuel to smoke your roomate. Go with 850/1680 or 720/1680's. Though 425-450 could probably be done with 550/1680's if you don't mind pushing them a little harder and upping the fuel pressure some.

mono4lamar

iTrader: (32)

On pump fuel you'll need to add methanol injection. It's completely do-able. Upgrade to 850's and 1680's and you'll be covered for the life of your mods. As for the Walbro's, they're fine. They only fail if they suck in air for a period of time. Double up on them and you'll have enough flow. When you do the fuel system you'll have to add an Aeromotive FPR. I'm undecided on using factory fuel lines, at least for the feed. I would run a 6an line up from the carrier assembly for the feed. Good to hear your car's coming along. I hope to meet up with you in the future...

classicauto

iTrader: (3)

Untrue. I can (and have) ran 20+psi on a GT3574 usign 91 octane and 500cc of water........with EGT's under 1700F on each rotor.

And to the OP - its "unsafe" to do so on pump fuel alone, but it has been done and will be done again. Busted7 here runs 500whp on straight 93 pump and has for A LONG time.

Busted7

Still running 20 psi on pump but i dont want to push anyone else into it and have them have a problem!
Be safe!

arghx

iTrader: (3)

^ What timing (leading and split) and AFR are you running?

Busted7

I cant tell you about split but 11.1 afr and 17 deg.
Steve Kan tuned the engine over a year ago and i didnt ask to many questions im no tuner!

ErnieT

iTrader: (2)

On my old FD, I was making just over 500whp w/ no ai . My fuel system consisted of a Apexi fuel pump, stock primary injectors, 1680 secondaries, SX FPR, and stock fuel lines. This was with the POS SR Motorsports Holeset turbo and a stock reman. I was running a Haltech E6k on that one.

Dudemaaanownsanrx7

iTrader: (23)

^^^ did the engine last? i figured the stock primaries and 1680's would flow enough for 500 hp, though they probably are at their limits around that level.

was that on pump gas?

ErnieT

iTrader: (2)

Why wouldn't the engine last? I have almost 800whp and the engine lasts. Injector duty cycle was at 80-85% which is fine. No it was on C116, but that doesn't matter for the fuel system. If your gonna try 500whp on pump, I'd suggest getting an AI system. BTW, water injection does not make you loose power, on the contrary, you will gain power. Since water doesn't burn it acts as a displacment adder, hense more power.

Dudemaaanownsanrx7

iTrader: (23)

I was asking if it lasted because i thought maybe yours was on pump gas since the op wanted 500 on pump. I've seen at least 3 people report that WI caused them to lose power. But that is most likely due to not retuning for it. In which case if it fails the engine pops. If you keep the tune the same and add water you gain the reliability but at least according to some you lose power. I don't run any ai first hand so it could be inaccurate, i'm just relaying information i've found on the forum from others. that run AI.

TwinCharged RX7

iTrader: (14)

I'll be considering meth injection for 500. and I'm going to see if someone will trade me their 850's for my 1300's and just modify the primary rail.

I'll get 1680's, a secondary rail that fits, and an FPR. undicided on which pump at this point, probly a supra pump.

might go on hold for a bit though, anyone check out my post on the fd section? hope I don't need a rebuild.

I found the real problem towards the bottoms of the 3rd page, please feel free to comment if you have any experience with this. only 350 miles so far I'll be pressure testing tonight to see if it fixed it but i'm doubtful.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/thermostat-question-798139/page3/

darkphantom

iTrader: (2)

i have the same setup as you do. 550/1600 but to be on the safe side get a external fuel pump. those twin setups ive seen some problems plus with the external fuel pump that will last you if you wanna go more. 8an lines is what id recommend.

ErnieT

iTrader: (2)

Actually you couldn't be more wrong. An external pump is much less reliable than an internal pump. An external pump can and will burn up twice as fast as any internal pump. My twin bosch setup will out flow almost any external pump out there and last 3 times longer.

darkphantom

iTrader: (2)

WHEN the guy (frogot his name) came to tune from gotham racing we had alot with the twin setups 2 had bad wires. at least with the external pump you have easier access as they were out there all night fixing the problem

TwinCharged RX7

iTrader: (14)

I'd like to stay internal just b/c thats the way it already is. I'm thinking either 2 walbro's or 1 denso supra pump, possibly the apexi that earnie mentioned, i'm not sure of the price on that yet though.

I'm just going to keep track of the classified and scoop up a good deal over the winter on injectors when i see one. Now that I know what I need I can start shopping. Thanks everybody.

Earnie- not sure if you checked out my coolant thread above but any ideas? I'm guessing you've had pretty much any problem one can have by now.

mono4lamar

iTrader: (32)

I've got a pair of 1680's and 850's (top feed) in my shop. They're my extra set. I also have a spare fuel carrier assembly. I can modify it and wire it up to what you want. I would stick with two Walbo pumps. Just be careful to get "no name" Walbro's. They do exist!!! If you want a good quality Walbro I can get you some. LMK when you're ready and I'll take care of you