forged 5e info

[AdamB]

It is completely correct fuel flow mate.

I would advise if you were looking to "add on a bit" then to ensure that your horsepower target is higher than it is actually going to be, for example I knew Shaun was going for 350bhp, so say 400bhp for a safety margin and also the injector duty cycle at 90%, some injectors can be run at 95%, but thats the chance you take

Also take into account that fuel flow changes with temperature, hence why you get more fuel from a petrol pump in cold mornings

So ensuring that your duty cycle has around 5-10% leeway before the injectors start max'ing out is a good idea to play safe.

Edited January 2, 2013 by AdamB

[little dave]

So I effect it is rule of thumb because your allow percentages for each thing there's no way this could be worked out spot on as you would have to allow so many different things as each engine is different but this truly helps as you have worked out my engine for me that's my goals for the min lol but would it not be wise to go up injector a bit due to the fact your turning up fuel pressure which will make the fuel a little harder to control am I right in thinking this ?

[AdamB]

As an engine builder/ student designer most would tend not to go above 4 bar fuel pressure. I myself still find this a little high and try to keep it as low as possible. There is no need to go up an injector size UNLESS your injectors do not flow the required amount of fuel at 4 bar fuel pressure, or in my preferable case 3.5 bar fuel pressure.

It is exact, you just have to be wise in how you use it. You could if you wanted to, use injectors which flow 550cc per min at 3.2 bar fuel pressure, this may mean your injector duty cycle is at 95% though and they could burnt out under high rev'ing conditions.

If for example you go for 1000cc injectors and your only at 400bhp, you will find that they may be easy to control during high loads, but at idle it will be a serious struggle and you will need some serious engine management system which has great injector control, such as the KMS ecu.

Edited January 2, 2013 by AdamB

[_shaun_]

Ok found it here goes lol

Fuel Flow (cc per minute) = (Horsepower Target* 5.6) / Number of cylinders

So say for an example for you Shaun:

Fuel Flow (cc per minute) = (400bhp * 5.6) / 4

Fuel Flow = 560cc Per minute

The next step is to look at what size injectors we need to provide this fuel flow of 560cc.

Injector static flow = (TF*100) / ( N*F)

Where TF is the Theoretical flow rate which we worked out to be 560cc.

N - Number of Injectors per cylinder

M - Maximum duty cycle of our injectors

So lets plug some numbers in:

Injector Static Flow = (560cc*100) / (1*90)

Injector Static flow = 622.22cc per minute

Now to include our fuel pressure we use the following formula:

Revised Static Flow = SF * Sqroot (RP/OP)

SF - Injector static flow at manufactures standard pressure (usually tested at 3 bar)

RP - Revised Fuel pressure

OP - Original manufacturers standard pressure

So say we use SARD 550cc injectors which were tested at 3 bar fuel pressure.

Revised Static Flow = 550cc * Sqroot (3.5 bar/2.4 bar) 3.5 bar as to increase flow rate of our 550cc SARD, and 2.4 bar is the stock base fuel pressure

Revised Static Flow = 664cc per minute.

So we can see that if we choose the SARD 550cc injectors, increase the fuel pressure from 3 bar of which they were tested at, to 3.5 bar, we get 664cc per minute, which is more than we calculated above of 622cc per minute.

Conclusion is that at 3.5 bar fuel pressure, SARD 550cc injectors will flow enough for Shaun's setup of 400bhp.

Hope that helps

spot on mate i was just gonna guess ha that actualy makes for intresting reading one question tho for Fuel Flow (cc per minute) = (Horsepower Target* 5.6) / Number of cylinders do u take hp from fly or wheels?

[AdamB]

Horsepower from fly mate. Essentially the flywheel horsepower is the Actual power the engine is making. The wheel horsepower is what is actually put down to the ground.

[little dave]

Ok bud I would always rather ask the question this is really helpful tho mate I will get sum 550cc injectors ordered up do agree this should be a wiki tho

[shorty]

Of course its never dead on balls acurate like say calculating the size ofa steal beam as weather heat fuel etc etc will constantly change but id say its very very close and id be happy using it if i need to calc my injectors. but i jave 550's sat here already lol. defo should be pasted some where as is very useful to have that for ref for future builds imo.

[_shaun_]

while we are getting all techy anyone care to explain how to choose the right size head gasket now aswell

[little dave]

Yea second this ^^^

[AdamB]

Always allow for a factor of safety and you can't go wrong. When I originally calculated what injectors, my fuel flow was up around the 780cc area because I didn't want to run anymore than 3 bar fuel pressure. May change my mind now so I can get cheaper injectors lol.

Glad its helpful.

while we are getting all techy anyone care to explain how to choose the right size head gasket now aswell

Whats your max boost you plan on running? What fuel octane do you have available to you? Whats the car going to be used for?

Edited January 2, 2013 by AdamB

[_shaun_]

2 bar is the goal 2.5bar at verrrry max but its doubtful normaly 98 octane? just standard super unleaded

[little dave]

1.6 to 1.8 bar max really same fuel as above but it's going to be a track car

[AdamB]

If your looking to run 2.5 bar at the max, I would suggest a 1.4-1.6mm headgasket. It also varies on the pistons you are going to use.

If your using Wossner/Ross where they are fairly flat tops, I would probably go for a 1.6mm. Wiseco pistons have a large dish on them so you could get away with a low compression ratio without having to go for the next size up gasket.

It really depends on what your mapper is comfortable with really, and how you want it to drive. If you want lots of mid range power your going to want as much ignition advance in the low-mid range area of the map. If its an out and out drag car your going to want power at the top end of the rev range so go for a thicker gasket to reduce the compression ratio.

My car is a 5e, looking to run 2.1 bar max boost pressure, and going to run an 8.5:1 CR as I want it to be super responsive, and not much lag.

[AdamB]

1.6 to 1.8 bar max really same fuel as above but it's going to be a track car

If its going to be a track car I would advise using Wiseco pistons where their piston-wall clearence is larger, since your engine temp is going to be much higher on track, the metal is going to expand further.

What turbo will you be using? Its important to try and keep the turbo in its efficiency range as its the cold air that makes power.

On track I would be looking for a fairly high compression ratio engine with a good standalone engine management system, probably run a 1.2mm headgasket, but run ARP headstuds and main studs from the 4AGE to keep a good clamping force.

Again its all down to your mapper whos comfortable with setting up an engine of this calibre.

If I was going to build a dedicated track car I would be using a 4e engine, with Wiseco pistons, pauter rods, ARP headstuds and main studs, 1.2mm headgasket and look for a compression ratio of around 8.4-8.5:1. If your budget stretches far enough even look into some mild cams which will help draw in more air higher up in the rev range.

Edited January 2, 2013 by AdamB

[_shaun_]

using ross pistons and realy id only push 2.5bar if i was happy with the results at 2bar. looking for a responsive set up its all windy b roads down my way so you reakon a 1.6 then?

[AdamB]

Depends on the turbo really Shaun, personally I wouldn't be looking to run 2.5 bar on the road, I would stick to 2 bar max, save 2.5 bar for drag days. Remember its alright having the turbo to produce that boost, but its also going to take longer to reach it.

If you stick to 2 bar max I would say 1.2mm-1.4mm headgasket will be sufficient enough for your needs, and since your 5e you will have the bottom end torque as well

Edited January 2, 2013 by AdamB

[_shaun_]

aye quite true i supose just waiting on dam customs to bill me for my car then i can see what i have left to start buying more bits

dont supose your rather well versed in sensors for the dta units

[little dave]

Gt30 turbo mate it's not going to be a dedicated track car it's going to be a road toy but the odd track day may be on the cards but nothing drastic an I've got my heart set on the 5e now and defo the turbo I have I just want sum fun an sensible power not pushing the bar pressure up to much causing more issues an this way its got plenty of torque

[little dave]

And was going to run the pistons and rods from cj performance as there's a budget and I can't see they will be an issue to use and was going to use racetech to build perhaps or tunning developments unless there's someone else people suggest

[_shaun_]

if your on a budget id build it urself thats my plan

[little dave]

I'm happy to do alot of it but the botTom end is very important and want it done by a pro

[AdamB]

Drop me a pm Dave and we can talk about it more mate.

I can't wait till the end of the month so I can get my "secret" turbo kit on the go lol. What do you wanna know about the sensors mate?

[_shaun_]

realy a list of every sensor i will need so far am thinking

cam sensor

crank sensor and trigger wheel

4bar map sensor

oil pressure sensor (after market)

oil tempt sensor (after market)

throttle body+ tps to be decided

air intake sensor (after market)

fuel pressure sensor?

after speaking to keith most of them will be aem sensors but wondering the easiest option for cam sensor. no sure what trigger wheel will work best for the dta and realy not sure best option for throttle body and tps was thinking one from a k20 as bean runs this and i already have a loom with the k20 plugs on it but then theres alot of hastle with trying to match the throttle body to the intake manifold

[AdamB]

The cam sensor you can use the stock sensor mate. It is an inductive type so not as accurate, but it does the job! I do have the wiring diagram for it somewhere.

With the throttle body, I've heard the Skyline GTR throttle body is virtually a direct fit to the 4E/5E intake manifold, if your going for an aftermarket inlet it may be more tricky, but the manufacturer should be able to supply a sensor to fit their throttle.

I personally wouldn't run a fuel pressure sensor, its ok to have as a fail safe, but not needed as if the pump every starts to fail you will notice on the wideband.

And theres a sensor your missing from the list lol. Wideband to allow closed loop control.

The innovate widebands are awesome but can be a bit hefty on the price tag.

Are you going to be running a boost controller or are you wanting the ecu to control boost? You'll need a boost solenoid, something like what comes with the Apexi AVCR, think they are around £70 last time I looked.

Edited January 2, 2013 by AdamB

[_shaun_]

yea fuel pressor sensor i wasnt to sure on.

just plan to run the standard intake to start with and see how i get on have herd the gtr tps was great for our cars but didnt click on the whole throttle body was.

i have depo wideband gauge sitting in the garage can this be used for the dta or do you need one for the ecu and one for the gauge?

yea sorry i want the ecu to run the boost so a solenoid is on the list to.

now when i bought my dta unit it came with a custom turbo charged k20 loom. i hope to use this as it looks shit hot quality tbh i assume all the air/map/oil sensors would be fine just to leave as they are just fit the correct plugs. for the injectors/coils they are all wired up in singles so would i be right in thinking i just need to check the firing order on the k20 and the 4e and if they are a different order just swap round the numbers to match the 4e firing order?

then i can just ditch the v-tech crap off the harness and wire in the boost solenoid and what not?