Unique: Throttle Bodies|Intake Plenum and Manifold

ruchi · Post by **ruchi** » Thu Aug 19, 2004 5:38 pm

As stated above, I'm using simplified terms.

In reality, any extra fuel passed through the injectors due to a higher increase in pressure from the FPR would be neglible. I would be very surprised if it was as high as the 10% you mention (it could be, but I would be surprised), but even if it was the effect this would have on the air/fuel ratio would be minimal.

The other thing to keep in mind is the standard ECU would try to compensate for any change in the air/fuel ratio to bring it inline with it's fuel mapping, again virtually neutralising the mod.

As the changes are negligble and as I'm using simplified terms so as to avoid getting detailed and confusing, I've stated that the change would effectively be none, yes there may be some, but it would be so small in the scheme of things that for the average person it's not worth considering unless you're upgrading the rest of the components and doing serious engine mods.

GPXXX · Post by **GPXXX** » Thu Aug 19, 2004 5:42 pm

how about designing an intake plenum whereby the throttle body would sit on driver side instead of the passenger side

wildfaye · Post by **wildfaye** » Thu Aug 19, 2004 5:43 pm

ok, so let me summarize what i have learned so far:

the stock fuel pump and injectors are more than sufficient.
the stock fuel regulator is already supplying a little extra fuel via the injectors(running rich).
the addition of the the rising rate FRP will be able to prevent the fuel rail from suffering from a lack of fuel at sudden accelation, at the same time be able to supply a little less fuel at normal driving situations to enable fuel economy and to prevent running rich.

Chiangstar · Post by **Chiangstar** » Thu Aug 19, 2004 5:44 pm

ok...these are exactly the two schools of thought ive been struggling with...

so steve, youre saying that using an FPR to increase fuel pressure, given stock fuel pump, stock injectors and normal fuel, can still richen the mixture by a small amount because more fuel can be 'forced' through the injectors at higher fuel pressures BUT at some point, no matter how high the pressure is, no more fuel can physically be forced through the injector

and ruchi, youre saying that unless you upgrade the injectors, there will be negligible increase in fuel supply and, in any case, the ECU would compensate for the richer mixture

hmmmm time to find a dynp tuner and get their opinion

simon

Chiangstar · Post by **Chiangstar** » Thu Aug 19, 2004 5:48 pm

GPXXX wrote:how about designing an intake plenum whereby the throttle body would sit on driver side instead of the passenger side

hahah lol

ruchi · Post by **ruchi** » Thu Aug 19, 2004 5:53 pm

Wildfaye:
The stock fuel regulator is also sufficient unless you do MAJOR engine mods.

The FTO runs rich because of the ECU fuel mapping not because of the pressure of the FPR.

Even under extreme acceleration the stock FPR will still supply enough fuel.

Chiangstar:
Technically by increasing the fuel pressure it could force a smidge more fuel through, but in real terms the effect is neglible and it would have very little effect on the air/fuel ratio. I seriously doubt you could notice it, you could probably only measure the differences using electronic equipment.

Unless you're upgrading the other components and remapping your fuel system the changes would be neglible and you'd be MUCH better off spending your money on other mods which would give a greater gain.

wildfaye · Post by **wildfaye** » Thu Aug 19, 2004 6:04 pm

So we shld get a aftermkt A/F controller like the Apexi SAFC2 to fine tune the mixture right? will we still require a FRP if we do this?

I still done understand the need for the FRP

Chiangstar · Post by **Chiangstar** » Thu Aug 19, 2004 6:18 pm

ruchi wrote:Wildfaye:
Unless you're upgrading the other components and remapping your fuel system the changes would be neglible and you'd be MUCH better off spending your money on other mods which would give a greater gain.

well i got one when i got my headers about 2 years ago cos i read about leaning out when you put in better flowing headers... i just took their word for it since i didnt know and i didnt want to worry about exploding engines

but since ive got it now, im looking for better ways to use it... i also have a digital AF meter and fuel controller but the problem is, you cant really do much without the use of a dyno... unless you hammer the car around and get a mate to sit in the passenger seat and adjust the fuel to about 13:1 while you drive around

hmmm....

simon

Chiangstar · Post by **Chiangstar** » Thu Aug 19, 2004 6:23 pm

oh yeah...back to topic...

so we dont know yet whether or not we'll need an FPR or fuel controller to go with the ported TB and IM but at the moment it looks unlikely?

we'll know for sure once the products are tested on the dyno?

simon

ruchi · Post by **ruchi** » Thu Aug 19, 2004 6:33 pm

To really oversimplify this...

lets work backwards:

- lets say that at full throttle the engine requires 1L of fuel per minute.
- to ensure that the engine receives enough fuel the car makers use injectors that are capable of delivering 2L per minute.
- to ensure that the injectors have enough fuel the FPR keeps more than enough fuel in the fuel rails e.g. 4L per minute.
- to ensure the FPR can keep enough fuel in the fuel rails to supply the injectors the fuel pump provides fuel at a rate of 8L per minute.

Even though the injectors can supply 2L per minute, the ECU limits the rate to whatever the engine requires, all the way to a maximum of 1L per minute at wide-open-throttle.

So by upgrading the FPR (or injectors or fuel pump) you are increasing the flow of fuel available to the engine, but the ECU will only let through what the engine requires based on the fuel mapping that has been programmed into it. So there is no need to upgrade these parts unless the fuel requirements of the engine has increased due to MAJOR engine modifications. You would also require an after market ECU to allow you to customise the fuel mapping, plus lots of dyno time to get it right.

As more fuel is pumped through than is required, the excess simply gets sent back to the fuel tank via the fuel return hose.

Please note that these figures are used solely to provide a simplified example.

Does this make it a little clearer or just more confusing?

wildfaye · Post by **wildfaye** » Thu Aug 19, 2004 6:42 pm

Ok Ruchi, now define "MAJOR"

Chiangstar · Post by **Chiangstar** » Thu Aug 19, 2004 7:10 pm

ruchi wrote:
Does this make it a little clearer or just more confusing?

No that makes sense...

"major" could be something like cams i guess....

simon

MADFTO · Post by **MADFTO** » Thu Aug 19, 2004 7:31 pm

Anything that requires an Aftermarket ECU to get the best performance.

You can't run standard fuel maps when you've changed the timing due to a change in something internally in the engine. They won't provide the maximum gain when changing internals.

ruchi · Post by **ruchi** » Thu Aug 19, 2004 8:26 pm

The standard FPR provides enough fuel for the standard injectors. Again, working backwards, you would upgrade your injectors when they can no longer provide enough fuel (leaning out) to meet the needs of the modifications you have done. Likewise you would upgrade the FPR inline with the size of the new injectors.

You shouldn't need to increase any of this with standard intake and exhaust mods, but you probably would if you had intake and exhaust combined with agressive cams and all the various boring out that has been spoken of in this thread. I would consider this to be serious modifications are these make significant alterations to the engine and would require an after market ECU to handle all the adjustments to the fuel rates and mixtures, likewise a fair bit of dyno time to tune it all. It would also greatly effect the drivability of the car making it more of a track car than a day-to-day car, so the mods aren't for everyone.

Post by **smorison** » Fri Aug 20, 2004 8:56 am

ruchi your example above is correct however i think you've overstaked the abilities of the equipment in the FTO... knowing car manufacturer's i'd say that the total oversupply capacity would be in the range of 50% not 800%..

a FPR shouldn't be required for these modifications...

a AFC or similar maybe useful to control the AFR better ... time will tell... (i've almost finished with my (jap mivec adapter) wiring diagrams and should have a VAFC ready to go into my car next week... if i can get a VAFCII to work i would recommend this as it gives you the ability to modify CAM engagement point as well as all the functions of a AFC...

CAM's well that's a different kettle of fish and we should probably move any questions relating to this to the other thread to keep everything consistent.

a competent tuner on a dyno shouldn't require more than 1 1/2 to 2 hours on a dyno to tune a AFC to meet the requirements of these mods... even adding cams wouldn't add much to this...

ruchi wrote: It would also greatly effect the drivability of the car making it more of a track car than a day-to-day car, so the mods aren't for everyone.

definately however the intake won't effect day to day driving really, it may increase fuel economy and that's about it... the CAMS... well as they're still in design we don't know how much they'll effect normal driving my thoughts were to retain the low-speed CAMs and make mods to the highspeed cams... this way the car is easy to drive at low speeds / low rpm... and doesn't bounce around at idle...

G_A_V · Post by **G_A_V** » Fri Aug 20, 2004 9:13 am

oh but there is nothing like the sound of a lumpy cam down low with the bouncing idle

Post by **smorison** » Fri Aug 20, 2004 9:15 am

G_A_V wrote:oh but there is nothing like the sound of a lumpy cam down low with the bouncing idle

hahah true...

but we're not 5.0 v8's either

ruchi · Post by **ruchi** » Fri Aug 20, 2004 10:23 am

smorison wrote:ruchi your example above is correct however i think you've overstaked the abilities of the equipment in the FTO... knowing car manufacturer's i'd say that the total oversupply capacity would be in the range of 50% not 800%..

You're right Steve, but as stated the figures were purely to provide a simplified example. I just doubled the capacity each stage to show the concept of each component supplying more than enough to the next stage, in reality this would not be a doubling each time, it would probably be closer to 15-30% more at each stage.

From memory the injectors run at around 80% of their capacity. So in very simply terms, if you made modifications to the engine that would require around 25% more fuel, you'd need to upgrade the injectors and probably also the FPR.

Again, I'm keeping things simple, so the figures are not accurate or indicative of real-world situations, they are just to help explain the concept.

Perhaps it's because I normally get very detailed and technical whereas this time I'm over simplifying things just to help people understand the concept

MADFTO · Post by **MADFTO** » Fri Aug 20, 2004 11:44 am

*laughs* if you want a lumpy cam sound, get a VAFC and change you mivec point to 1k rpm =)

300 degree intake duration should provide that for you =)

Post by **smorison** » Fri Aug 20, 2004 11:51 am

MADFTO wrote:*laughs* if you want a lumpy cam sound, get a VAFC and change you mivec point to 1k rpm =)

300 degree intake duration should provide that for you =)

LOL

if only the VAFC would let you adjust it that low... 3000rpm is about the min you can engage it....