Injector HP Capability

[SanTa_]

I have a set of RC Engineering 750cc ATM in a box that was purchased awhile back (last year or so)

My turbo set up consists of a:

t67 p-trim t3 DBB .82ar
tial 40mm WG
Straight line specialties t3 manifold with XL runners

No worries on other fuel mods, but I'm more confused on the injectors.
My gains are around 450-550hp.

I assume this injector will do. If not I was planning on upgrading to higher injectors like 880cc's.

Will my 750cc's do?

 

[AWD_Hybrid]

The engine will require around 6cc of fuel per minute per horsepower.
750cc x 4 = 3000/6 = 500hp @ 100% duty cycle.
Those @ 80% duty cycle = only 400hp
Go bigger injectors.
Cheers !

 

[SanTa_]

Thanks mate!
I'll go with the FIC 950's


Will that be fine with my set up?
2.0 bored .020 over with original oil squirters
b-shaft elimination
arp head studs
arp main studs
arp rod bolts
eagle H-beam rods
wiseco .020 8.3:1 cr pistons
machined block deck surface for 4 layer mitsu steel HG
slowboy racing stage 5 head
-manley SS stock sized valves
-manley titanium springs/retainers
-viton stem seals
-bronze guides
-3g lifters (revised for no ticking)
comp101200 camshafts
90 style oil filter housing
ACL race main bearings
ACL .010 over crank/rod bearings
full balanced rotating assembly
.033 piston to wall clearance
.019 top ring
.017 bottom ring, if memory serves me correctly
all professionally assembled

Engine was align honed, bored with a torque plate.
All timing components are mitsu, NAPA water pump (i like their design better, they have a better wheel design then OEM, just my personal preference)

All gaskets are OEM.

My turbo setup:
t67 setup

Straight line specialties t3 manifold with XL runners
t67 p-trim t3 DBB .82ar
tial 40mm WG


- With supporting mods of course. or should i bump up my injectors to the 1050's?

 

[GORBS88]

The engine will require around 6cc of fuel per minute per horsepower.
750cc x 4 = 3000/6 = 500hp @ 100% duty cycle.
Those @ 80% duty cycle = only 400hp
Go bigger injectors.
Cheers !

Injectors are rated at 43.5psi so wouldnt they flow alot more since the FP under boost is gonna be alot more? maybe im wrong.?

 

[dirtbike_79]

The whole reason for a rising rate fpr is to keep the same pressure on the injectors at all times. When there is pressure in the manifold(boost), it acts as a force on the tip of the injectors. So what the fpr does is add pressure to the fuel side of the injectors to keep the overall pressure constant. Hope this clears things up a little bit.

 

[GORBS88]

The whole reason for a rising rate fpr is to keep the same pressure on the injectors at all times. When there is pressure in the manifold(boost), it acts as a force on the tip of the injectors. So what the fpr does is add pressure to the fuel side of the injectors to keep the overall pressure constant. Hope this clears things up a little bit.

Thats makes sense, never knew that..
But if a injector is rated at 750cc AT 43.5 psi, It WILL flow more fuel at say 60 psi wont it?

 

[AWD_Hybrid]

SanTa you haven't cut corners with hardware that's for sure !
Are the ACL bearings 3/4 groove ? 3/4 groove ones ware better
on the power stroke. Just a coupla tips from my eng builder, who
preps & rebuilds cranks for the best top fuel dragsters etc in Aus.
The countersunked oiling hole on mains can be hand die ground
like a tear drop to advance the oil suply timing also. All tech stuff,
but my mate presses 30mm dia molly bar into the counterweights
for added rotating weight & knife edging etc. Another important
balancing point is, if the eng is for street, he will balance the crank
spinning at 140rpm & 200rpm for ski boats & drag engines.
The 1050's will be ok & handy if you plan using high boost.
The T/B dia is more critical when it comes to street drivability.

GORBS88 the deadtimes open/shut period is what determines how
much fuel gets through the injectors, as well as the injector size.
So too small a choice of injectors running @ 100% duty cycle will
be lean @ your 60psi. Larger injectors running with a lower duty
cycle, can be pushed to a higher psi, because they have reserve.
But the eprom needs to know & or the aftermarket comp.
Cheers !

 

[donniekak]

An injector that flows 750cc's at 43.5 psi rail pressure will flow 750cc's at 63.5 psi rail pressure and 20 psi manifold pressure. The purpose of a fpr is to keep the pressure differential constant.

 

[endeffect0]

The whole reason for a rising rate fpr is to keep the same pressure on the injectors at all times. When there is pressure in the manifold(boost), it acts as a force on the tip of the injectors. So what the fpr does is add pressure to the fuel side of the injectors to keep the overall pressure constant. Hope this clears things up a little bit.

thats not the whole truth.
A rising rate FPR does compensate for the pressure in the manifold. But when your fuel pressure goes up because of the FPR the volume your fuel pump can supply goes down... hope this can shed some light.

Walboro 255lph

10psi = 63.53lbs/min
13psi = 61.48lbs/min
16psi = 59.10lbs/min
19psi = 56.39lbs/min
22psi = 53.34lbs/min
25psi = 49.97lbs/min

 

[SanTa_]

Well for running boost I would like to do 15-20psi on the street, and then 30-35psi on the tracks.
So I assume anything over 950's are well than efficient?

 

[AWD_Hybrid]

A friend of mine has the eprom info for RC 1,000cc injectors &
their deadtimes. I'll be using them for street/strip.
Cheers !

 

[endeffect0]

I dont know what your compressor map looks like... how many Lbs/min will your turbo be flowing at 20psi. that should be the real question

950cc injectors should be able to handle 55lbs/min of air at 80% duty cycle.. or 68lbs/min wide open...

 

[SanTa_]

-T04R 67mm compressor wheel with a max flow rate of 75 lb/min

No compressor map as it's not tuned or put together.

 

[endeffect0]

a compressor map just shows the flow and efficiency of a turbo, it can usually be found on a manufactures website but in this case google did disappoint.

well if your going to be getting to the upper limits of that 75lb/min flow you may well need larger injectors than 950's. the numbers i posted for them were for standard fuel pressure and a 11.1afr tune. so if you want to turn the fuel pressure up you may be able to get away with more out of the 950s perhaps consider looking for a set of 1100s ?

also you didnt mention what fuel pump you will be using. a standard wally doesn't have the numbers to cover it. denso suppra 260 pump would get you alot closer to that 75lbs/min. or maybe a dual wally setup is more your flavor.

 

[SanTa_]

Yeah the wally set up. I was looking for 400-500hp though. Should I have a supra 260 pump rather than the wally for those goals?

 

[endeffect0]

well it depends on which wally flavor you have. assuming its re wired and a 255, could still either have the lph or the lph-hp

255lph
10psi = 72.15lbs/min
20psi = 64.34lbs/min
25psi = 59.58lbs/min

255lph HP
10psi = 74.29lbs/min
20psi = 69.99lbs/min
25psi = 67.80lbs/min

so really when you look at it, neither pump will get you into the 70lbs/min range at 30 psi..

the denso supra 260 pump will get you really close. hopefully close enough.
10psi = 82.91lbs/min
15psi = 80.17lbs/min
25psi = 74.30lbs/min

with 30 psi you can expect it to be below the 70lb /min mark.. but its still close and if you not maxing out the turbo you might not quite max out this pump.
but if you have 1 wally it might be just as effective to go with two wallys.. which will cover your ass the whole way.

 

[the_mork]

If you're flowing that much then I would suggest a Bosch 044 fed by any flavor of wally.

 

[SanTa_]

Thanks for the info! I'll do the two wally setup. The pump along with the inline wally.

I'll also have Fuelab 828 Series In-Line Filter 5" Length w/75 Micron Stainless Steel, Aeromotive Fuel Rail, Full Blown 2g DSM Dual Walbro Kit w/ two 255lph hp

Or should I go with a kit like the "STM | 90-99 DSM FUEL TANK TO RAIL KIT" instead of that In-line filter alone

 

[SanTa_]

Should I do the two wallys or the Bosch 044 inline with a wally?

 

[SanTa_]

Anyone? Read above. Thanks

 

[AWD_Hybrid]

As the_mork posted, a wally feeding a bosch 44 will do.

I have a wally feeding a surge tank & 2 bosches feeding each
end of my fuel rail. I welded a bung in the fuel rail centre to
run my automotive fpr from. A bit over the top some will say.
Cheers !

 

[SanTa_]

I'll go with the denso supra 260 pump.

Since they're very close to the flow rate of the 75min/lbs.

If I'm looking to pertain a goal of 400-500HP then I should be fine with this. And with that pump I can just increase the boost up more for future numbers.
And then if this happens add a Bosch 044 in-line.

 

[phunny]

Now that you have a plan, go make it happen.

 

[SanTa_]

Now that you have a plan, go make it happen.

+1 Ordering my flywheel and shroud kit first though =[
Do a lot of vendors sell the denso 260 pumps?

 

[the_mork]

You may want to check on price and availability. A Bosch044 + wally setup will surely pump more than a denso260 and IIRC they are not that much more expensive. I also believe that you could feed an 044 with a stock fuel pump and still make significant flow.

This thread has a fairly nice and comprehensive list although it does not include the 044. I think I'll actually make a request because it should probably be in the list if possible.
http://www.dsmtuners.com/forums/tuning-engine-management/244522-injectors-fuel-pumps.html