??? Fuel system needed 800rwhp
#46
01-14-2010, 08:47 AM
BTW I'm not a huge fan of dual pump setups and try to do one pump if possible. The reason being is that if one pump goes out then you'll never know until it's too late. The car will run fine until the fuel demand goes up and then you'll run lean enough to kill the engine. If one pump goes out then you know you have an issue. I know there are scenarios where a single pump can start to go bad too and lose flow, but the risk is just doubled with two pumps.
Just putting this out there to think about.
-Martin
Just putting this out there to think about.
-Martin
#48
01-14-2010, 01:15 PM
Looky looky, what do we have here?
I built a fuel pump test stand years ago so we could test stock fuel pumps and to help us develop fuel upgrade kits. Tony at EPL sent me a stock pump and here it is compared to a Bosch -044 and stock GTR fuel pump setup for reference.
The stock 996tt pump is good for easily 700-725whp at higher fuel pressures (using a 5 bar FPR), and more at lower pressures. An ideal setup on a stock fuel pump would be a stock FPR and larger injectors to handle the fuel deliver, I'd say a set of injectors in around 1000cc/min and that would probably max out the fuel pump at somewhere in the 750 to maybe 800whp range.
I built a fuel pump test stand years ago so we could test stock fuel pumps and to help us develop fuel upgrade kits. Tony at EPL sent me a stock pump and here it is compared to a Bosch -044 and stock GTR fuel pump setup for reference.
The stock 996tt pump is good for easily 700-725whp at higher fuel pressures (using a 5 bar FPR), and more at lower pressures. An ideal setup on a stock fuel pump would be a stock FPR and larger injectors to handle the fuel deliver, I'd say a set of injectors in around 1000cc/min and that would probably max out the fuel pump at somewhere in the 750 to maybe 800whp range.
How about if you have a stock FPR and 60lb'ers...running ~ high 500RWHP on GT28's @1.4 bar of boost on pump. Do you feel 3.8 bar would work better or 5.0 bar of fuel pressure. Both seem to work with little ups and downs and it seems borderline.
Does the data show a better option in that range?
Thanks,
#49
01-14-2010, 01:26 PM
Looky looky, what do we have here?
I built a fuel pump test stand years ago so we could test stock fuel pumps and to help us develop fuel upgrade kits. Tony at EPL sent me a stock pump and here it is compared to a Bosch -044 and stock GTR fuel pump setup for reference.
The stock 996tt pump is good for easily 700-725whp at higher fuel pressures (using a 5 bar FPR), and more at lower pressures. An ideal setup on a stock fuel pump would be a stock FPR and larger injectors to handle the fuel deliver, I'd say a set of injectors in around 1000cc/min and that would probably max out the fuel pump at somewhere in the 750 to maybe 800whp range.
I built a fuel pump test stand years ago so we could test stock fuel pumps and to help us develop fuel upgrade kits. Tony at EPL sent me a stock pump and here it is compared to a Bosch -044 and stock GTR fuel pump setup for reference.
The stock 996tt pump is good for easily 700-725whp at higher fuel pressures (using a 5 bar FPR), and more at lower pressures. An ideal setup on a stock fuel pump would be a stock FPR and larger injectors to handle the fuel deliver, I'd say a set of injectors in around 1000cc/min and that would probably max out the fuel pump at somewhere in the 750 to maybe 800whp range.
#50
01-14-2010, 03:43 PM
As for why lower pressure but larger injectors is better for power production it's simply because as you raise fuel pressure the pump moves less VOLUME. Volume is what you want as this is truly what goes into the cylinder. So, a larger injector and normal volume flow more than high volume on a smaller injector - there's also the issue that some injectors have issues opening under really high pressures if you take it to an extreme.
#51
01-14-2010, 04:11 PM
How exactly are you sensing the failure?
As for why lower pressure but larger injectors is better for power production it's simply because as you raise fuel pressure the pump moves less VOLUME. Volume is what you want as this is truly what goes into the cylinder. So, a larger injector and normal volume flow more than high volume on a smaller injector - there's also the issue that some injectors have issues opening under really high pressures if you take it to an extreme.
As for why lower pressure but larger injectors is better for power production it's simply because as you raise fuel pressure the pump moves less VOLUME. Volume is what you want as this is truly what goes into the cylinder. So, a larger injector and normal volume flow more than high volume on a smaller injector - there's also the issue that some injectors have issues opening under really high pressures if you take it to an extreme.
As far as which one is better at the 650hp level, it is kind of a wash. The lower pressure regulator would be easier on the pump, while the higher pressure one would mean a lower duty cycle for the injectors. I have not seen a significant amount of failure form the stock pump or aftermarket injectors, so in the end it's a wash. I would personally perfer the lower pressure reg, but your tuner might like tuning with the higher pressure unit.
#52
01-14-2010, 10:49 PM
Correct. Injectors are usually rated at 43.5psi of rail pressure. When you increase thate pressure you are increasing the amount of fuel the injectors flow when they are open. However, with the increased pressure there is more resistance to flow for the pump, lessening it's capabilities.
As far as which one is better at the 650hp level, it is kind of a wash. The lower pressure regulator would be easier on the pump, while the higher pressure one would mean a lower duty cycle for the injectors. I have not seen a significant amount of failure form the stock pump or aftermarket injectors, so in the end it's a wash. I would personally prefer the lower pressure reg, but your tuner might like tuning with the higher pressure unit.
As far as which one is better at the 650hp level, it is kind of a wash. The lower pressure regulator would be easier on the pump, while the higher pressure one would mean a lower duty cycle for the injectors. I have not seen a significant amount of failure form the stock pump or aftermarket injectors, so in the end it's a wash. I would personally prefer the lower pressure reg, but your tuner might like tuning with the higher pressure unit.
Oh, it should also be noted that double the pressure != double the fueling capacity of an injector. In fact different manufacturers injectors of the same size might even fuel differently - best to get them tested IMO. It will probably also change responsiveness.
That said I would love to see a good parallel pump setup for these cars that sits in the tank and is as stock as possible. I realize the rails might be an issue etc. too but a parallel setup, assuming the return line is good, ought to support pretty decent power without tearing up too much of the car.
#54
01-15-2010, 08:17 AM
Join Date: Jan 2007
Location: Los Angeles, SFV
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dual pumps in tank
Evoms has a great in tank dual pump set-up with the -8 or -10 return line and an external regulator. $6500-7000 for the kit 
That said I would love to see a good parallel pump setup for these cars that sits in the tank and is as stock as possible. I realize the rails might be an issue etc. too but a parallel setup, assuming the return line is good, ought to support pretty decent power without tearing up too much of the car.[/quote]
That said I would love to see a good parallel pump setup for these cars that sits in the tank and is as stock as possible. I realize the rails might be an issue etc. too but a parallel setup, assuming the return line is good, ought to support pretty decent power without tearing up too much of the car.[/quote]
#55
01-15-2010, 11:28 AM
Evoms has a great in tank dual pump set-up with the -8 or -10 return line and an external regulator. $6500-7000 for the kit
That said I would love to see a good parallel pump setup for these cars that sits in the tank and is as stock as possible. I realize the rails might be an issue etc. too but a parallel setup, assuming the return line is good, ought to support pretty decent power without tearing up too much of the car.
That said I would love to see a good parallel pump setup for these cars that sits in the tank and is as stock as possible. I realize the rails might be an issue etc. too but a parallel setup, assuming the return line is good, ought to support pretty decent power without tearing up too much of the car.
+1.... I think someone needs to come up with a dual in-tank bracket like Titan carries for the Supra. I think one can do it for a lot cheaper than $6k
Last edited by dgreen78; 01-15-2010 at 11:32 AM.
#56
01-15-2010, 11:32 AM
+1.... I think someone needs to come up with a dual in-tank bracket like Titan carries for the Supra. I think one can do it for a lot cheaper than $6k![/quote]
I built one for my Supra for the cost of an 044 pump and Aeromotive fittings?
I built one for my Supra for the cost of an 044 pump and Aeromotive fittings?
#57
01-15-2010, 11:50 AM
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I know for a fact that a cheap dual series set up with 850 cc siemens genesis injectors will do 850 rwhp using 3.8 bar fpr
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2001 996TT 3.6L and stock ECU
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2001 996TT 3.6L and stock ECU
9.66 seconds @ 147.76 mph 1/4 mile click to view
160 mph @ 9.77 seconds in 1/4 mile click to view
50% OFF ON PORSCHE ECU TUNING BLACK FRIDAY SPECIAL
#58
01-15-2010, 12:07 PM
Hey mark, how many lbs is an 850cc? And do you mean the second pump will run is series after the factory?
#59
01-15-2010, 12:17 PM
We have seen multiple failures running them at pressure higher then 3.8, 4, and 5 bar.
The division of Siemens that made those injectors was bought out by continental and quality took a big hit at the same time.
This is the main reason we discontinued the use of this injector.