Fuel Pump
- Thread starter TheJimer
- Start date
Ian Anderson
Lifetime Supporter
Sorry to ask but have you calculated the fuel use specifications your engines will require when at full throttle?
Example
I run a Rover made 3.9 litre and have a Facit red top from tank to swirl and Bosch 044 to fuel rail.
The red top is marginal at keeping the swirl pot full
And my car makes a max of .......... 250 hp
A sump of only 1 litre for the HP pump seems a very small safety factor to me
Ian
Example
I run a Rover made 3.9 litre and have a Facit red top from tank to swirl and Bosch 044 to fuel rail.
The red top is marginal at keeping the swirl pot full
And my car makes a max of .......... 250 hp
A sump of only 1 litre for the HP pump seems a very small safety factor to me
Ian
Ian, indeed I did. I don't have it in front of me, but it was well within range for 400hp and my application. Fuel pickup is at the way bottom of the tank and you have to pull crazy g's for a long time for zero gas to be picked up out of the main tank for an extended period of time. For a track/race car, maybe I'd go with a different setup, but for a street car that may see an occasional twisty track without big sweepers, this is enough. What's your calculation on the safety factor being too small?
Also, your Facet is a different pump. Check the link. The one I used has been used successfully by a number of builders with higher HP, bigger swirl pots and a track applications.
Best,
Tim
Also, your Facet is a different pump. Check the link. The one I used has been used successfully by a number of builders with higher HP, bigger swirl pots and a track applications.
Best,
Tim
Thanks. It's all Summit Racing store brand. Why pay more? Most of the time, white label stuff is made in the same factory as one of the major brands anyway.
On a side note, Summit is super sweet in SF. Almost everything comes overnight from Reno at the cost of standard shipping, so I basically buy everything I need from there.
Tim
Ian Anderson
Lifetime Supporter
Tim
I'm no expert but found a figure on this site that said 15cc of fuel per hp per minute
So your 400hp engine will use 400 * 15cc = 6000cc per minute at full power
So that 1 liter swirl has a capacity of 10 seconds of fuel.
Now if the LP pump is starved by a high g corner, then after 5 seconds you have only a half litre in the swirl.(Engine burnt the other half liter) This is also acted on by the corner G and you "may" have the HP pump suck air / cause lean fuelling.
It's better than no swirl pot set up but I would consider it small for your use.
Consider your dive home - fuel tank getting low - like 1/4 tank and a nice swooping on / off ramp from a highway - how many seconds could your LP pump see "air"?
Now your LP pump is 50gph free flow or suggested 20GPH at 6 psi
20GPH *3.8 = 76 Litres per hour = 1.3l per min
Even at free flow rate it equates to 190 l per hour = 3.2l per minute
This is about half of what your engine is drinking on full throttle / 1/4 mile drag etc.
Perhaps you need to look again at your calculations - I'm happy to be proved wrong but hate hearing about engines blowing up
Ian
I'm no expert but found a figure on this site that said 15cc of fuel per hp per minute
So your 400hp engine will use 400 * 15cc = 6000cc per minute at full power
So that 1 liter swirl has a capacity of 10 seconds of fuel.
Now if the LP pump is starved by a high g corner, then after 5 seconds you have only a half litre in the swirl.(Engine burnt the other half liter) This is also acted on by the corner G and you "may" have the HP pump suck air / cause lean fuelling.
It's better than no swirl pot set up but I would consider it small for your use.
Consider your dive home - fuel tank getting low - like 1/4 tank and a nice swooping on / off ramp from a highway - how many seconds could your LP pump see "air"?
Now your LP pump is 50gph free flow or suggested 20GPH at 6 psi
20GPH *3.8 = 76 Litres per hour = 1.3l per min
Even at free flow rate it equates to 190 l per hour = 3.2l per minute
This is about half of what your engine is drinking on full throttle / 1/4 mile drag etc.
Perhaps you need to look again at your calculations - I'm happy to be proved wrong but hate hearing about engines blowing up
Ian
Ian,
Thanks for your concern. I appreciate it.
I'm not sure where you're pulling 15cc / HP / minute from. Flow rate depends greatly on a number of factors, but most importantly turbo vs. naturally aspirated, which mine is. The calculation then uses something call the BSFC (brake specific fuel consumption) as a multiplier to adjust for different types of engines. Street NA is 0.5, turbo 0.6, race NA below 0.4.
There are many calculators out there like this one (RC Fuel Injection) but the math is dead simple anyway. It's just HP * BSFC / duty cycle % = lbs / hr. Multiply by 10.5 to get cc / min.
Using some really pessimistic assumptions of 80% duty cycle and sustained no flow from LP pump gives a range of 2100 - 2615 cc / min. That means 28 to 23 seconds of flow from a 1 liter pot. Note that the pot's pickup is at the way bottom especially if it's mounted at 45 degrees like mine (look a the design drawing on the 034 website).
I'm confident that this pot is enough, but let me know if you still disagree.
Regards,
Tim
Thanks for your concern. I appreciate it.
I'm not sure where you're pulling 15cc / HP / minute from. Flow rate depends greatly on a number of factors, but most importantly turbo vs. naturally aspirated, which mine is. The calculation then uses something call the BSFC (brake specific fuel consumption) as a multiplier to adjust for different types of engines. Street NA is 0.5, turbo 0.6, race NA below 0.4.
There are many calculators out there like this one (RC Fuel Injection) but the math is dead simple anyway. It's just HP * BSFC / duty cycle % = lbs / hr. Multiply by 10.5 to get cc / min.
Using some really pessimistic assumptions of 80% duty cycle and sustained no flow from LP pump gives a range of 2100 - 2615 cc / min. That means 28 to 23 seconds of flow from a 1 liter pot. Note that the pot's pickup is at the way bottom especially if it's mounted at 45 degrees like mine (look a the design drawing on the 034 website).
I'm confident that this pot is enough, but let me know if you still disagree.
Regards,
Tim
Just got off the phone with one of the Radium guys: Fuel Surge Tanks
They are coming out with a surge tank shortly that has an integrated pressure regulator. That is 3 less lines to fail and will make for a very clean installation. Here are some dimensions on their tanks: http://data.radiumauto.com/PublicDocs/FST_DIMENSIONS.PDF
I did some measuring and I think it will fit fine in the opposite corner to the tank standing straight up or maybe a bit angled. The working volume of their standard surge tank is 1.5 litres. So far this one is my choice.
They are coming out with a surge tank shortly that has an integrated pressure regulator. That is 3 less lines to fail and will make for a very clean installation. Here are some dimensions on their tanks: http://data.radiumauto.com/PublicDocs/FST_DIMENSIONS.PDF
I did some measuring and I think it will fit fine in the opposite corner to the tank standing straight up or maybe a bit angled. The working volume of their standard surge tank is 1.5 litres. So far this one is my choice.
