Fuel System upgrade for 9 sec (non E85) ?

[chris kirk]

Don't see me going E85 anytime soon since it is nowhere to be found near me in MD...looks like only 7 stations offering it in the whole state according to an online search and none close enough to consider. Right now I don't want to pull/drop the rear and tank to add a sump and am I'm leaning towards an in-tank pump to get me going. I'll be changing to a 9" rear next Fall so if I decide to sump the tank that will be a good time. I don't need to drop my tank to change the pump since my car has a access panel that I installed back in 2008...don't hate

That's a pretty nice option! Plenty of in-tank pumps to get you there. I would talk to Nick Micale, he has a bunch of options that would be good for your application. Just keep the future in mind.... I know I've done things over on more then one occasion costing me triple the money....

 

[87GN_70GS]

No need to sump with an external. Just run the in-tank and external in series. The in-tank pump will be unloaded and will feed just about anything. The external has fuel supplied to it without having to develop suction and will flow more than a single pump configuration.

 

[chris kirk]

I actually tried that years back before (early/mid 90's) ever going to a big external pump. Years and years ago nobody (at least to my knowledge) made a strong enough internal pump, (ESP said they did, but they didn't) so the external inline pump was an option if you had an internal pump and wanted to increase volume and pressure. The problem I had (maybe not everyone) was internal couldn't keep up with external inline pump. Then I tried a different internal pump to closer match the external inline, and ugh, what a mess.... Ended up being a giant mess. Wires everywhere.... Spent a shit load of money and was no better off. So I just gave up on it and went external. Now with all the technology today I think it's a matter of preference at least until you get into serious hp.

 

[WHTTRSH]

So whats the biggest intank pump we can run in these TTA's for 600-700WHP? Racetronix 430 or Walbro 430 will do the job? Or we have to go w the A1000 external setup...Im in the same boat as Scott right now. The dual Walbro 340s intank w hotwire are out of the picture??? 80# injectors are enough...no need for 120#s. Whats going to get the job done w the least amount of headaches. Im looking at running the Gen2 6466 turbo instead of Scotts GT6776 though too so i might not need as much fuel.

 

[WHTTRSH]

Would prefer not to spend the $$ either, 4k, switching to E85 and running ProEFI.

 

[turbo89]

So whats the biggest intank pump we can run in these TTA's for 600-700WHP? Racetronix 430 or Walbro 430 will do the job? Or we have to go w the A1000 external setup...Im in the same boat as Scott right now. The dual Walbro 340s intank w hotwire are out of the picture??? 80# injectors are enough...no need for 120#s. Whats going to get the job done w the least amount of headaches. Im looking at running the Gen2 6466 turbo instead of Scotts GT6776 though too so i might not need as much fuel.

dual intank DW301's .. no problem supporting that power level ... quiet , flow more than enough to support the level of performance .. great pumps

 

[WHTTRSH]

K cool, what about single pump setup then?

 

[turbo89]

K cool, what about single pump setup then?

My preference would still be dual intank pumps ... the dw301 are the right pump in that they can supply plenty of fuel just in a single configuration without getting into replacing return line setups ... going over this size pump you need to open the return line ..

twin 301's supply more fuel than any 109 can handle

 

[WHTTRSH]

That's what I'm running w then thanks for your input!

 

[Scott89TTA]

Whttrsh, the 6776 was my old setup...new is a PT7168HPQ also running Fast Xfi.

 

[WHTTRSH]

Gotcha! Should I go bigger then a gen2 6466...I'm running a stroker motor as well but not looking to do launches/drag race it. Looking for the biggest turbo that's still streetable. Ill launch it at lights don't get me wrong haha but if I'm rolling next to some goof on the street I would prefer it spool quickly. A turbo your size still streetable or not really.

 

[Scott89TTA]

I sure hope it's streetable...my car will be mostly street driven. I have several buddies with similar builds as mine and the same turbo and they are very happy...don't seem to have any spool issues.

 

[murphster]

Just to add my 2 cents.....

I actually had a second pump fail to turn on at the track a few years ago. Never did find out why it didn't turn on. Luckily it wasn't turned up and with the alky I had enough on the single pump so it didn't do any damage. I caught it reviewing my log and looking at the fuel pressure log. After that I went to a single external pump, my thinking that if there is a major issue I will probably catch it beforehand and less to worry about as far as testing whether the second pump is coming on, etc.

Looking at the flow of the Walbro 430 posted on the previous page and running some simple calcs here is what I come up with:

800hp should require something like 83# inj at 80% duty cycle. Total flow would be 83 x .8 x 6 = 398 lb/hr. Dividing by 6.2 lbs/gal for gas gives 398/6.2 = 64 gal/hr. If you run 43psi static fuel pressure and 27psi boost thats a total of 70psi. At 70psi and only 12V the Walbro 430 puts out 78.7 gal/hr so you are covered.

83# injectors are capable of flowing 83 x 6 = 498 lb/hr or 498/6.2 = 80 gal/hr. So at 12V those injectors can outflow that pump. Your 120# injectors will outflow that pump at 12V at 67% duty cycle.

Now compare to an Aeromotive A1000 at 12V and 70psi. It flows about 580 lb/hr or 93.5 gal/hr. This would outflow 83# injectors and give you up to 80% duty cycle on the 120# ers. An Aeromotive Eliminator flows about 770 lb/hr or 120 gal/hr at 70psi and 12V. This one can outflow the 120# injectors.

 

[Scott89TTA]

Just to add my 2 cents.....

I actually had a second pump fail to turn on at the track a few years ago. Never did find out why it didn't turn on. Luckily it wasn't turned up and with the alky I had enough on the single pump so it didn't do any damage. I caught it reviewing my log and looking at the fuel pressure log. After that I went to a single external pump, my thinking that if there is a major issue I will probably catch it beforehand and less to worry about as far as testing whether the second pump is coming on, etc.

Looking at the flow of the Walbro 430 posted on the previous page and running some simple calcs here is what I come up with:

800hp should require something like 83# inj at 80% duty cycle. Total flow would be 83 x .8 x 6 = 398 lb/hr. Dividing by 6.2 lbs/gal for gas gives 398/6.2 = 64 gal/hr. If you run 43psi static fuel pressure and 27psi boost thats a total of 70psi. At 70psi and only 12V the Walbro 430 puts out 78.7 gal/hr so you are covered.

83# injectors are capable of flowing 83 x 6 = 498 lb/hr or 498/6.2 = 80 gal/hr. So at 12V those injectors can outflow that pump. Your 120# injectors will outflow that pump at 12V at 67% duty cycle.

Now compare to an Aeromotive A1000 at 12V and 70psi. It flows about 580 lb/hr or 93.5 gal/hr. This would outflow 83# injectors and give you up to 80% duty cycle on the 120# ers. An Aeromotive Eliminator flows about 770 lb/hr or 120 gal/hr at 70psi and 12V. This one can outflow the 120# injectors.

Murph good info...so what I'm gathering is the 120's are too big if used with anything less than a dbl pump or external like a the A1000 correct? If I were to go with the Walbro 430 the 120's will out flow the pump at 67% DC...what is the result of outflowing the pump? Bare with me I'm learning...

 

[murphster]

I was just putting that info out there so you had an idea. The 120#s do seem like way overkill if you aren't doing E85. Only drawback besides them not being needed is if they are harder to tune at idle compared to the 83#s etc. Have to ask people running them and see what they say.

And as far as the pump, that depends on how much overhead you want and what your plans are. You'd have a little over 20% spare room on the 430 on race gas. But as you turn up the boost past 27psi (or 70psi total) that margin goes down. And if the pump puts out a less than that spec thats a little more margin. And if you want to run a little richer than needed thats even more margin gone. That pump is probably the bare minimum you'd want to run....

 

[pacecarta]

this seems to be often misunderstood when choosing a pump for the goal or combo
9s depending on weight you need 750+ hp , with a bsfc of .5 (1/2 lb fuel per hp) divide by 2 thats the fuel you need . 325 lb /hr + 25% for safety
325 x 1.25= 406 lb/hr ..divide x 6 = 67 ..add 20% since you dont want to run static but at 80% or less and you need an 80# injector ( yes you could push a 60# there but thats your decision and if you come up short it wont be pretty)

simple way to look at your needs is gallon /hour (gph) is the same as lb/ hour on injector since fuel is approx 6lbs per gallon and we run 6 injectors ,
83# injector X 6 injectors is 500lb hr
so for pump you need 83 gph thats 500 lbs per hour ,

now kEEP to the 80% inj duty limit (any more and you should consider a larger injector) you still want at least 83 gph from your pump so for safety your pump has 125% of the injector intended max flow meaning the pump health will have to drop 25% before youll experience a fuel issue . if you pick your pump without the safety margin from the day it goes in it will begin to flow less every day it runs so it will eventually bite you in the ass

now theres also some confusion when they state flow in litres ,litres divide by 4 is gallons ( close enough ) simple ..if 83# injectors just multiply injector x4 , so you need a pump(s) that flows 332lph (that is with 125% safety) , that doesnt mean grab a 340lph pump and youll be fine ...thats the rating at 45psi ..you need a pump that flows that rate at your target fuel pressure based on your boost. lets say that is 25psi .. 45base +25 boost=70psi fuel pressure --the pump needs to flow 332 lph at 70psi , for 30# boost you need to look at the 75 psi flow rating.

that said murph and myself are running 83# inj the 71hpq (7168) and pump and alky and the injectors are under 70% inj duty

oh and dont decide on a pump that needs a specific voltage to get your flow and you rely on a volt booster to get enough fuel and it fails you could be in a bad place , or if the alternator dies (or belt slips or flies off) and voltage drops to battery you'll be in a bad place . Ive been down the track at 12v no problems

 

[Scott89TTA]

Thanks Murph and Paul, So I'm assuming when you stated 750+ hp for 9's depending on weight that is crank HP or are you saying whp ? From what I'm told my motor should make mid 600's at 22-25psi at the rear wheels...putting me ~mid 700's at the crank with estimated 20% drive train loss and a good bit higher on race fuel at 28-30psi ? I'm guessing I will run most of the time on a XFI street tune in the 24-26psi on 93/Alky (dual nozzle) and and also have a race fuel XFI race tune possibly in the 28-30 psi range eventually when the rest of the car chassis/drive train is ready for that. The car is in pieces right now getting it ready for the new motor, fuel system and roll cage. Now is the time to do the fuel system and attempt to get it right...I haven't skimped anywhere else and don't plan to on the fuel system. It was suggested to me that I go 120's over the 80's I already had if ever intend on turning it up (28-30 psi). I would think that 67% DC isn't a bad thing for the 120# injectors with the Walbro 430...obviously the A1000 is a better match for the 120's but is it still way overkill for my need/goal?

 

[pacecarta]

rear wheel..flywheel ??? i like to use real world
this might help

 

[pacecarta]

and heres my 86 figures from the 9.72 pass (found another 50hp since then)
you start by entering the weight and et (either desired or actual) in top row it computes the figures in the second column data (shaded ) , take the calculated hp put in first window on top row and it computes the first column data (shaded)
.it also figures the fuel ...look on the v6 chart at right , 100% would be flow in lb/hr per inj

you can see this computed data all matches up very well to my actual real world experience of 67% injector duty on an 83# inj

 

[murphster]

Your numbers may be off a little..... At 25psi on that turbo I'm over 800hp at the crank. Either way, once you know your weight you can guess how much rwhp you need to run 9s, if that is your goal. I would say the 80# injectors would have been enough to run the numbers you stated on race gas, but the turbo is capable of more HP so maybe the 120#s were a good idea.

But using Pauls example of 25% margin at 12V, he is saying that if your fuel demands an 83# injector at 80% duty cycle you need a pump that will flow 83 x .8 x 1.25 = 83gph. At 70psi (25lbs boost) that 430 pump only puts out 78gph. Its not enough pump for what that turbo is capable of on race gas unless you keep it turned way down. You have the injectors, turbo, etc. I wouldn't skimp on the fuel pump.