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Surge tank under hood?


turbogrill
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Hi,

 

Installing a surge tank under the hood would be ideal, it's a very easy install and plenty of room.

 

However is this a bad idea from a safety perspective? The engine bay is huge so it will be far away from other things. 

 

The other option would be in the rear but that requires a bit more tricky installation.

 

Internet seems to have different opinions.

 

 

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2 minutes ago, turbogrill said:

Hi,

 

Installing a surge tank under the hood would be ideal, it's a very easy install and plenty of room.

 

However is this a bad idea from a safety perspective? The engine bay is huge so it will be far away from other things. 

 

The other option would be in the rear but that requires a bit more tricky installation.

 

Internet seems to have different opinions.

 

 

 

I would put it in an enclosure on the passenger side of cabin before under hood, but both can work. Vapor lock might be an issue underhood

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We are having the same debate as a team, we want to locate it above the main fuel cell, but below the filler neck so that our vent line will allow the return line to fill the sump during a pit stop...   that is the most important, but we also would like to have the swirl pot and hits motor as close as possible to the fuel rail...  we have considered the cowl area, or other areas inside the frame rails (like were the OE battery tray is)...  but so far my team mates disagree on the safety and location.

 

On one hand, you already have fuel, oil spark, and heat all exposed, you have high pressure fuel in rubber lines in the engine bay...   it doesn't seem wrong necessarily to shorten the amount of high pressure fuel line...   nor does a small amount of fuel seem to be any more dangerous than other things that might be in your engine bay (like a battery).   but then again, it is substantially easier to just mount it on top of the factory fuel tank, it has the least extra plumbing, and seems like the easiest to firewall, if most all of the fuel is just in the one spot.

 

So far on our build, safety and convenience are winning...  the swirl pot is in the back.

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I put mine in the engine bay, mounted to the intake side of the engine actually.  I didn't want any fuel in the cabin. 

 

Stock routing uses hard lines under the car and then a piece of rubber hose at the firewall to make the connections to the fuel rail.

image.png.a2ca0a8b2908fa59a7289337e6a346a0.png

 

 

My surge tank had the new HP pump mounted right to it with a short hose feeding the pump from the bottom of the surge tank, then this whole "module" has two ins and two outs that just hook up to those same hard lines under the car and at each end of the fuel rail. There are more hoses and more connections to be sure, but minimal changes to the stock stuff. 

image.png.c7812faf5116e4ac5a4e7db9c14b4d93.png

 

 

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Same as mine.

 

Not so long ago it was very clearly stated in the rules that the surge tank could not be plumbed to act as additional capacity i.e. fill at the same time as the main tank.

 

I just checked and that verbiage is not there. Question: was it taken out because of a rule change or just to shorten the rule book?

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I think when the surge tank was reduced from 2 gallons to 0.5 there was really no need to have the plumbing methodology discussion.  If an extra 0.5 gallons in the surge is going to make your day by adding capacity then go for it.

Edited by Ron_e
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57 minutes ago, Team Infiniti said:

Mender aside, are people literally using fuel the bottom of their surge tanks to get that last lap?

 

 

Yup, I have a catalog sorted by track of fuel consumption versus average lap time curves with shift point recorded.  We weigh every jug before and after a fill then calculate fuel consumption on gallons per hour then adjust RPM shift point for each driver.  Thankfully we have three that are pretty close but one typically burns fuel faster at an extra 0.5 gallons per hour more.  We juggle stint lengths and yellows on the fly with trying to run the three more fuel efficient drivers to 1:57 then we can run the less fuel efficient to 1:49.  The odds of a full course yellow in the first stint are higher so he typically gets first stint to try to make 1:49.  We intentionally target odd hour races so we can jack up the shift point another 400 RPM (typical) as everybody runs shorter stints.  At a new track I have to estimate our fuel burn then keep the fingers crossed until after we do one fill then once I can calculate the fuel burn I can radio the second driver to say if he can exceed the RPM shift point buzzer by another 1-200 RPM till he finishes then I can hop in the car to adjust the shift point in between a driver change for the third driver.  This gets fine tuned as the race goes on and I can average more than one data point.  Of course if there is a full course yellow I have to time it then I cut the fuel burn in half for that period of time to calculate the average fuel burn for that particular stint.  Once chips became free we did a custom tune on the dyno to optimize AFR solely for fuel consumption optimization.  Yes a few times I have gotten it wrong with not enough margin and we ran out of fuel with 0.5 laps to go.

 

You should try it, it is a lot of fun, totally awesome!

Edited by Ron_e
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56 minutes ago, ABR-Glen said:

That actually does sound fun, I wish everyone had to be that strategic.

 

Me to, I'm willing to share the wealth, one less fuel jug for everyone at every fuel stop.  Except Mustangs and Fiero's of course, we are already running one jug short.  In fact you can start employing this type of strategy today, just stop filling your fuel tank, only go maybe 3/4 full at every stop.

Edited by Ron_e
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2 hours ago, ABR-Glen said:

That actually does sound fun, I wish everyone had to be that strategic.

It would be if everyone had an equal amount of fuel. Not so much fun when you have to drop out of the game because of fuel either by cutting back the revs or ducking into the pits early.

 

Either way it's frustrating to watch otherwise equal teams drive away.

Edited by mender
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17 hours ago, mender said:

Same as mine.

 

Not so long ago it was very clearly stated in the rules that the surge tank could not be plumbed to act as additional capacity i.e. fill at the same time as the main tank.

 

I just checked and that verbiage is not there. Question: was it taken out because of a rule change or just to shorten the rule book?

 

Its always extra capacity....   IE if your surge tank is full when you pit stop fine, then its full when you leave... 

 

I had heard of

teams pausing during fueling to switch on the fuel pump, fill the surge, then top it off...  say doing that between jugs...

 

Similar to teams that might lift one side of the car to burp the factory tank...   doing this can add significant capacity to some systems...   5 minutes gives teams with small tanks plenty of times to mess around for those last few liters.

 

 

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