rxing87

i want to gain more hp and stay naturally aspirated

i know i have to get higher flowing injecters
my question is :
Cant i get some higher lb/flowing injecters with no adittional upgrades ?

i know this may make the engine run too rich
(do i have to go into the cpu to correct?
or can i just change the fuel pressure at the regulater or can i use the air/mixture screw on the throtle body?

i really don't want to deal with the computer

kevino

Unfortunately if you are changing injector size then you have to deal with the cpu. There are easier ways to gain quick horsepower, like aftermarket exhaust and intake systems which is as easy as bolt on (if you haven't done this already). If you still want to alter the fuel system be sure to do it right. Probably the easiest way to do it is to get a piggy-back fuel management system (ties into the cpu wires). Take it to a local tune shop that has a dynanometer and have the air/fuel ratio set throughout the rpm range. You'll probably also need a larger fuel pump to utilize the bigger injectors. Do some searching on this topic in the 2nd gen archive and you'll find a lot more info. By the way don't touch that throttle set screw if you don't have to, it can be a bitch to set right.

rxing87

hows bout with a ignition controller
shouldn't be able to utilize the timing

so lets say i do go with an injector upgrade what kind of power can i expect to gain (13b natural aspirated engine 1987)current hp 140-what 160...i want to gain 60-100hp can i do it piggy back fuel controller.,ignition box ,timing controller....??

jesse_fc3

I could see 160-170hp with those upgrades

rxing87

gain or overall



(gain)

jesse_fc3

overall thats just what i would guess do you have any other upgrades cuz that would make a difference in gains

rxing87

completely stock.....
another quick ?

i want o make around 350 hp naturally aspirated.....i know i may have to replace my transmission at 260-320hp........or would putting a realy good hp clutch do the job

CasperIV

You are going to need more rotors... I seriously doubt you have the money to get anywhere near that number without either a turbo or a 20B, neither option is cheap in it's own right.

Sprockett

350HP NA

rxing87

hows bout with a custom racing intake manifold with 2 throttle bodies...........

ever see one before?
i sen one on a honda had 4 throttle bodys

hers a pic

http://us1.webpublications.com.au/st.../3049_10lo.jpg

Icemark

If this is for a 2nd gen RX-7, the absolute last thing you want to do is put bigger injectors in it.

The stock injectors are fine up to about 225 hp... considerably more than you will ever get with the engine stock otherwise.

Normally to get more HP out of a 2nd gen non turbo you actually need to lean the mixture out. The last thing you want to do on a stock non turbo is give it more gas... this is not some lame lean burn Honda.

Icemark

Bull ****... he will be lucky to see 125HP at the wheels with those upgrades and probably considerably less.

The stock ignition is fine up to about 6200 RPM, so an ignition controller will do nothing but burn up spark plugs.

With a piggy back AFC he might be able to dial back enough on his "bigger injectors" to get maybe 10hp more.

And the only thing he can do with timing is crank it up a little, for maybe a couple of HP, but then it pretty much requires a CDI unit to keep the spark intact at above 6500- and what is the point of that since the stock internals and intake on that motor run out at 7000 rpm.

NoDOHC

Seriously, please do a search, this has been covered so many times it is scary.

Search for "Maximum NA horsepower" or something like that. In fact, several other people have asked this same question already tonight.

Bigger injectors give you more fuel. To use more fuel, you need more air, how do you get more air??? Rev like crazy or strap on a turbo. Without air, the additional fuel does not help.

I am running bone stock everything except for advanced timing and aftermarket exhaust (custom fab with dynaflow mufflers) and I have 138 hp to the rear wheels. This was after adding ethanol to the gas to LEAN THE MIXTURE UP. I made 134 rwhp on ordinary 87 octane. If you add fuel you will richen the fuel mixture, causing a net decrease in horsepower.

I have heard that people have gotten up to 176 rwhp with the stock intake, ecu and ports.

They did it with stock injectors :>)

For 350 rwhp, go turbo or go home. Even a $20,000 custom fabbed peripheral port setup will not give you that on a 45 °F 0 humidity day.

Spark notes: You don't need bigger injectors

rxing87

check out the pic,,,,,,,,,,,

i know i need more air

Icemark

Won't give you what you need.

Remember horns are tuned for a specific RPM, and the S4 FC motor runs between 500 and 7000 RPM. What RPM are you going to turn those horns too?

If you are looking at staying with stock internals, you need to look at a better less restrictive exhaust (with a non turbo, probably less than 2.5" in dia), then look at a standalone or major ECU upgrade.

Then you can look at things like a ported S5 intake system and motor port tweaks.

I spent a year building my last non-turbo motor, and only could do 173 RWHP (peak) and still made it pass the sniffer test in CA. There is no way to get above 200-225 RWHP on a S4 non turbo without forced induction or major porting, or Nitrous.

rxing87

isnt the idea of trying to add more air is to increase cfm

i would like to stay within stock rpm range

maybe 8000rpm max without porting

with porting(dont want to do to much of)10,000 11,500

i hear that the mass air flow/sensor limits cfm.......is there .there no way to increase..air flow.....

okay fcs make 140 hp yea
or 160

ether way its :example 140divided by 4 spark plugs

35 hp per plug idealy my idea it to up the hp per plug

Icemark

well since the stock motor redlines at 7000. How you going to keep it together at 8000? Well alone that it starts running out of air at 6500 with the stock ports.

So you tune those horns to 8000 rpm what are you going to do at 2000 rpm or 3000 rpm or even 4000 rpm. Or is it just for drag racing and you are only going to run it at 7000 RPM, and never drive it on the street?

and what are you then controlling the engine with?

I think you are in over your head, and don't understand how the motor even works.

The AFM and throttle body are not the limit on the non turbo. They are the same opening as the Turbo motor uses. The same that have been used to hit 300-350 HP on a Turbo FC.

Icemark

You don't understand how the motor works.

Do you think that each spark plug is in its own piston or rotor or something?

You do know that it is a two rotor engine?

And that stock RWHP on the FC is 115 and 120. Flywheel HP on a very good compression motor is 146 and 160 peak.

cptpain

iTrader: (1)

Icemark: let him do what he pleases and have a mod close this thread. he obviously has no idea how a rotary works and how it reacts to modifications. he just wants to build a car to imitate some honda with ITBs cause its cool looking and he saw it on the internet and a youtube vid of how much power he can get with ITB's

let him blow his motor and waste his money. he'll cry and say we told him so

Icemark

Yeah, I think you are right! Now that you mention it... it appears that everything that he has said points to something that someone would do to upgrade a lean burn Honda motor...

NoDOHC

Don't feel like we are bashing you, you just need to understand that this is a 1.3Liter engine (let me say that again for emphasis) a 1.3 Liter engine.

You can't expect it to make 350 WHp without forced induction, that would require either 15,000 rpm or a VE way in excess of 100%.

Look on the internet for a 1.3 Liter 350 Whp piston engine that is naturally aspirated and then you will understand better why you can't do this.

Please understand a few basics, then you will see why we get frustrated:

The air all around us is at a fixed pressure (about 100kPa)
Air will only flow into a given sized chamber at a given rate at a given pressure.
In your case (holding to NA) you have fixed that pressure to that of the atmosphere (100 kPa).
You also have a fixed chamber size 2 at 0.654 Liters each.
Each time this chamber opens, it fills with the appropriate amount of air based on the pressure on the air.
Then Fuel is injected into the air at a certain mix.
Then the mixture is ignited, causing torque.

Thus, the torque output of a fixed size engine is fixed at fixed intake pressure.

Now lets introduce volumetric efficiency.

At 100% VE, an engine will produce about 120 lb-ft of torque per stroke per liter.
This should equate to about 160 lb-ft of torque from a 13b since it gets 2 strokes per revolution at .65 Liters each.

So even with 100% VE (very difficult to achieve)

Your engine will have to spin 11,500 RPM to make 350 Hp
350 Hp / 160 lb-ft * 5252 rpm*lb-ft/Hp or 11,500 rpm

Because 100% VE at those engine speeds is impossible, you will have to turn much faster, because you will not be making 160 lb-ft of torque.

A rotary engine will have to be heavily modified to turn 11,500 RPM, let alone the 16,000 that you would probably have to turn to get that power.

About your Independant Throttle Bodies and velocity stacks:

It is true, velocity stacks increase engine VE by acoustic resonance, at one engine speed, the pressure wave generated by the rotor clearing the port will bounce off the atmospheric air and come back to the port just as it opens. The reason that this is only at one engine speed is because the pressure wave travels at the speed of sound and takes that same amount of time to travel the same distance, regardless of the engine speed, thus the wave helps at some speeds and hurts at others.

However, the amplitude of this pressure wave is low (about 2kPa at most) This equates to about 0.2 psi of boost and will not help your performance significantly.

I have probably wasted that time, but I felt that I owed you at least a basic explanation of why we get so frustrated, at least one guy per day asks the same question "How can I get <insert insane horsepower number here>WHp out of my 13b without a turbocharger or porting". Liken that to, how can I run a marathon with my legs tied together and no training.

Spark Notes:Change the displacement, change the intake air pressure or change the requirement, you will not get that much power out of a Naturally aspirated 13b.

NJGreenBudd

iTrader: (1)

I have a full set of 550cc injectors that are for sale:

(4) 550cc Low Impedance Fuel Injectors TII

Good luck with your monster NA.

rxing87

ive seen a drag race rotory with 900hp,,,,,also had supercharge,turbo
still you have to make bout 450 550hp before the sc/turbo

idont think it was 13b ether,,,was datsun i think ,

rxing87

the noise of th sc/turbo i like alot ,,,,,but a hard mashing na ...id rather have

shhshshshhsshhsshhhhsssssshssssssssssssshhhh


ssspss sspss bov

at times i just dont want to hear it

88t2romad

ill sell you my 1680cc injectors, that will make your NA good to about 500hp