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Old 10-11-2018, 11:41 PM   #1
aruss99
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80lb injectors max whp

Hey guys, I am a college student trying to plan for what the bare minimums I need to upgrade on my fuel system to make around 1000hp at tx2k. I have a 1971 C-10 with a 5.3 LM7. It's has a rotating assembly in the works to support that kind of power (thinking TSP 6.125 rods and still undecided on pistons), but I really need help with fuel.

I was thinking of ordering some sort of fuel cell set up for an inline pump. I'm looking at the magnafuel 4303 with 10an line and then split into two -8 lines at the rail.

The issue I am struggling with is I currently have Siemmens Decka 80 injectors and I know that under normal circumstances these injectors can't support this power, however I only plan to make this much for TX2k, and then will turn it down to 800 for the street until I have the money for bigger injectors. I am going to be running on e85, but some race e90 may be used for just the event to be safe

My question is this, if I set the base pressure to something like 80 PSI and have it boost referenced, is it possible to make that kind of power, or is that kind of pressure inside the injector going to cause some sort of failure within the injector, mess up the spray pattern, or cause some sort of other issues?

Thanks for the help.
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Old 10-12-2018, 10:42 AM   #2
BR3W CITY
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Re: 80lb injectors max whp

Your computer is basing stock fuel calcs on 58psi. Your injector data sheet should say what rail pressure they were rated on. Increasing rail pressure that much means changing the working flow rate of the injectors, since injector flow is volume@pressure. Your 80lb injector could be more like 110lb with a ~30% increase in rail pressure...let alone whatever the boost ref commands. It'll be a tw@t to idle and part throttle it.

Injector Dynamics could get you set up, but that means $$$$

Otherwise you can buy yourself some margin and run a secondary fueling/meth system.
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Old 10-12-2018, 03:18 PM   #3
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Re: 80lb injectors max whp

if you dont want to spend a ton on injectors (sell your 80's) and grab a set of the bosch 210's or the snake eater performance 1500cc. proven results with both of those in high HP applications. Im not sure how efficient the pump would be at 80 psi, but most of those pumps drop flow with pressure increase.

base pressure of 80 psi means you are going be upwards of 100 psi if running 20 lbs of boost (only assuming this because you have a 5.3 and are trying to make 1000 hp). the dekas may not even work at 100 psi; i wouldnt gamble the motor on some injectors.
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Old 10-12-2018, 07:09 PM   #4
aruss99
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Re: 80lb injectors max whp

[QUOTE=BR3W CITY;8362789]Your computer is basing stock fuel calcs on 58psi. Your injector data sheet should say what rail pressure they were rated on. Increasing rail pressure that much means changing the working flow rate of the injectors, since injector flow is volume@pressure. Your 80lb injector could be more like 110lb with a ~30% increase in rail pressure...let alone whatever the boost ref commands. It'll be a tw@t to idle and part throttle it.

Injector Dynamics could get you set up, but that means $$$$

Otherwise you can buy yourself some margin and run a secondary fueling/meth system.[/QUOTE

I didn't realize meth systems were able to supplement the fuel system to that degree, but that does make sense that with enough meth I could back off on the injector fueling. That might be the best option, I've seen universal meth kits for $200 to $300 which is cheaper than new injectors, and when paired with e85, should give me some serious protection against knock.

I had read about people running 100psi through these injectors, but only a few so I wanted to see if those guys just got lucky with no failures, or if this was a somewhat common thing to do. Sounds like they were pushing their luck with those kinds of pressures.

Last edited by aruss99; 10-12-2018 at 07:11 PM. Reason: grammer
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Old 10-13-2018, 11:33 AM   #5
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Re: 80lb injectors max whp

All adding the meth kit will do is buy you margin, since your just looking for a way to get more fuel to the air charge.

I'll be frank and say that fwiw, I don't think the setup is practical. You need a LOT of fuel to support the power thats being discussed. Trying to do it on corn juice means ~30% more fuel flow demand on top of it.

Running a pump at 80-110psi is going to tax the pump. Doesn't matter what pump, its gonna be working hard. The 4303 drags nearly 20amps at 75psi...so your going to want a beefy hotwire for the pump, and keep an eye on it. You're also going to have the issue of how hot the fuel might want to get. You lose ~10GPH per 10PSI pressure increase from ~40psi per flow charts. The pump is also being rated at 12.5-12.7v, so anything less @ the pump will reduce output.

Race gas would help lower the fuel demand and net you some room overhead. If you haven't even put the thing together yet tho, any chance you can just rearrange the budget for some bigger injectors? No one turns it up to run "just once"
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Old 10-14-2018, 11:04 PM   #6
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Re: 80lb injectors max whp

Quote:
Originally Posted by aruss99 View Post
I was thinking of ordering some sort of fuel cell set up for an inline pump. I'm looking at the magnafuel 4303 with 10an line and then split into two -8 lines at the rail.
That is a great setup that will do what you need it to.

Quote:
Originally Posted by aruss99 View Post
I currently have Siemmens Decka 80 injectors and I know that under normal circumstances these injectors can't support this power, however I only plan to make this much for TX2k, and then will turn it down to 800 for the street until I have the money for bigger injectors. I am going to be running on e85, but some race e90 may be used for just the event to be safe
Deka 80's however are not going to make 1k RWHP under any circumstances, especially on E85. They likely won't even make 800 on E85, maybe on pump + meth but you'd be pushing it. If you want to make that kind of power you are going to have to step up to some larger injectors. I would recommend just going with Bosch 210's. They can be had for $550 from well known sellers but can be had cheaper through slightly less reputable sellers. 210's will support anything you ever want to make without getting into some seriously high dollar stuff. You could get half the cost of some 210s back by selling your 80's.

And personally I wouldn't bother with meth if you have E85 available locally.
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Old 10-15-2018, 11:49 AM   #7
aruss99
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Re: 80lb injectors max whp

Thanks for all the input, I will go ahead and order some 210's and sell the 80's to recoup some of the expenses.
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Old 10-20-2018, 08:43 AM   #8
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Re: 80lb injectors max whp

I've run the deka 80's on E85, at 610 rwhp. They were around 80% duty there...at 60psi rail pressures.
so I agree...if you want that kind of power, you would fall short with those.

I also caution that kind of power, on a 5.3 if you are running stock crank. You will be on borrowed time....use of the best rods and pistons you can get, will stress the crank more under full power....it's going to move around a lot...about all you can do is set the main bearing clearances looser side.
I've run a stock crank 5.3 at 1000rwhp+ thru a stalled 4L80...everybody on the internet says they are fine at 1000hp...they are fine for a couple bonzai pulls...but long term it will tear up mains due to crank flex. If you tear the engine down regularly for a refresh/inspection, you can maybe catch it before any real damage
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