| [ Total Views: 1626 | Total Replies: 25 | Thread Id: 72548 ] |
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 GTMac
A.k.a.: Andrew
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 posted on October 26th, 2008 at 10:53 PM |
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Fuel temps and performance???Edit EJ20 owners please read!
Guys, just asking the question, what effects does warmer fuel have on performance.
Only just noticed how hot my fuel tank gets, off course I have 2 big dirty thermo fans blowing hot air on them now from the front mounted radiator.
Easy fix to heat shield but thought ask question first.
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers. 
How many sets of lights does it take a $229k Carrera S to learn? 
UPDATE: Cayman S, M3, B4 now added to the list. |
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Jak Rizzo
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| posted on October 27th, 2008 at 07:12 AM |
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I remember back in the day Andrew that the old school racers used to take their fuel to the track in an esky. But I've seen recent dyno tests, one in
Zoom magazine the other on the Autotechnica? website saying that cold fuel compared to hot fuel did nothing for performance in back to back dyno
tests. I've seen those little fuel coolers that just go in line & hang in the wind under the car, but I figured not having one meant that it was
one less thing to go wrong?
Jak
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Baja Wes
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| posted on October 27th, 2008 at 10:11 AM |
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If it gets too hot your engine will stop. The main effect will be to make it vapourise and go out your tank vent. Not good for economy or the
environment.
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GTMac
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| posted on October 27th, 2008 at 01:29 PM |
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| Quote: | Originally
posted by Baja Wes
If it gets too hot your engine will stop. The main effect will be to make it vapourise and go out your tank vent. Not good for economy or the
environment.
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Interesting dyno results Jak, would not have thought that.
Wes, my fuel economy has seemed to gone down and everytime I open the petrol cap, so much pressure is released. So should I worry first about economy
or the enviroment?
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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VWCOOL
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| posted on October 27th, 2008 at 04:27 PM |
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Warm fuel is actually good for performance AND economy AND evap emissions. (Not that we care about the last factor much). Warm fuel vaporises more
easily. A lot of the Holden/Gen III brigade found this out the hard way when they tried to convert thier 'returnless' fuel systems and throttle body
pre-heat (coolant bypass) to the old skool systems used on the 5.0s; they dropped power and lost throttle response in some circumstances due to cold
fuel not vaporising. The reasoning was that cold material is denser, therefore you can pack more in when it's cold... makes more sense for intake air
than fuel
But not too hot mate!!
EDIT: What the other blokes above said is also true - too hot means possible running problems with vapour lock etc and you lose more fuel through
evaporation
Pay your debts, CxxT
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GTMac
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| posted on October 27th, 2008 at 06:23 PM |
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OK, Glenn says warm fuel helping with vapourising.....................etc etc and says not too hot, how about hot enough when I take the fuel cap off
it blows out of my hand, sprays fuel and the vapours that came out were that hot they burnt my hand!!!!!!
Anyway, why Im asking Ej20 conversion people and more than likely Type 3 owners to please read, is that this prob could occur and how to stop it.
As you know I run EJ20T and radiator up front thus when the thermos come on it blows more hot air than normal onto the tank area. OK the tech minded
are saying simply heat shield it, yes I will but why has the overheating only occurred in last 3 days and not over last 2-3 years.
I thought I would do the right thing and make a sexy looking aluminium shroud around the radiator which not only tidys up the front area but also
pushes the air out better than swirling around the old wheel well area..................guess what it works but pushes the air more extensively onto
the tank, thus the heating of the fuel and expansion of the tank.
Here is the bizzare thing, I drive 32 km to work and after exiting the M5 I have about 7km to go. Along this stretch I notice the steering becoming
tighter and tighter to the point I could let go and it would stick and stay what ever direction you pointed. What the hell is going on, steering box
stuffed, hope not only 2 years old, ball joint seizing for some reason, not likely and only 2 months old, how about the steering dampner?
Took her home and pulled it off and drove later on that night, perfect, problem solved so I thought order one the next day. Get to about the same spot
as day before and steering gets tight  what the hell now?
Start car afternoon and OK until about 1km from home it was that tight that I could not move steering wheel. This is when I opened the fuel tank and
near blew my head off.
The round coupling that is after the steering box was becoming cramped due to the fuel tank expanding that much, how bizzare is that? And I prob would
not have picked it for a while unless I looked back and thought, hang on, why after filling tank up 25km from home bound trip the steering was back to
normal.
So, let the car sit there for another 15min, start to drive remaining 1km and steering is good. Ohh and as Wes stated, the fuel econ will be bad, how
about 1/2 tank over 100km!
Hutcho and others, make sure you look at this scenario in your mods list and I will update should problems continue. Am hoping that I can keep the
shroud once I have put the heat shield around the tank.
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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VWCOOL
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| posted on October 27th, 2008 at 07:21 PM |
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that's another reason why the law says you must run a charcoal cannister... it will prevent that from happening by allowing the pressure to
even-out
I never would have thought it got THAT hot though... wow
Pay your debts, CxxT
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Hutcho
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| posted on October 27th, 2008 at 07:31 PM |
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Ooooooohhh.... thats NASTY, Andrew! On a day like today in Sydney (33deg) that would pose a real problem. I hate to say it but your lucky your tank
didnt blow. I wonder if there is a way to get real time fuel temp readings. I may come over and pay you a visit soon just to have another sticky beek
over your car if you dont mind. Im still l having a few drama's raising the motor. Ive fabbed up a bracket but it looks like Ill have to pull the
exhaust, a few ancilliaries and split the motor/box so I can get the braket on. Im so used to lying under the car now that I sometimes feel as though
I should just sleep there.
Good luck with your fuel issue, mate and Ill take on board what youve advised.
Steve
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GTMac
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| posted on October 27th, 2008 at 08:42 PM |
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| Quote: | Originally
posted by VWCOOL
that's another reason why the law says you must run a charcoal cannister... it will prevent that from happening by allowing the pressure to
even-out
I never would have thought it got THAT hot though... wow
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I am running a charcoal cannister  Thoughts now GT?
Yeah Steve more than welcome to come over and look, prob better as Im hopeless in getting pics of my mods up.
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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JVLRacing
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| posted on October 27th, 2008 at 08:45 PM |
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Breather hose from the tank?
Water pipes from rad...where are they located?
Are your fermos blowing the hot air from the rad back onto your tank?
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GTMac
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| posted on October 27th, 2008 at 08:49 PM |
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| Quote: | Originally
posted by JVLRacing
Breather hose from the tank?
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John, checked all those things this arvo, breather is on and its where the t-piece is for my charcoal cannister fittment.
Water pipes are well away from anything. Yes thermos blowing air onto tank but has always been like that.
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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JVLRacing
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| posted on October 27th, 2008 at 08:51 PM |
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| Quote: | Originally
posted by GTMac
| Quote: | Originally
posted by JVLRacing
Breather hose from the tank?
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John, checked all those things this arvo, breather is on and its where the t-piece is for my charcoal cannister fittment.
Water pipes are well away from anything.
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ok! wat about my last 2 questions...
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GTMac
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| posted on October 27th, 2008 at 08:52 PM |
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Your too bloody quick, I keep editing my post to keep up with you
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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JVLRacing
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| posted on October 27th, 2008 at 08:56 PM |
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is the rad right near the tank?
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VWCOOL
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| posted on October 27th, 2008 at 09:26 PM |
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| Quote: | Originally
posted by GTMac
| Quote: | Originally
posted by VWCOOL
that's another reason why the law says you must run a charcoal cannister... it will prevent that from happening by allowing the pressure to
even-out
I never would have thought it got THAT hot though... wow
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I am running a charcoal cannister Thoughts now GT?
Yeah Steve more than welcome to come over and look, prob better as Im hopeless in getting pics of my mods up.
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Yeah, I thought you were... Is there an easy way to check for blockages/kinks? Maybe blow through the lines?
Pay your debts, CxxT
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GTMac
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| posted on October 27th, 2008 at 09:34 PM |
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| Quote: | Originally
posted by JVLRacing
is the rad right near the tank?
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Id say there is prob 50cm between them but direct air blow onto the front and bottom side of the tank.
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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JVLRacing
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| posted on October 27th, 2008 at 09:44 PM |
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shit this is a prob! m8 is there any fuel blowing out of the breather with the tank expanding?
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1303Steve
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| posted on October 27th, 2008 at 10:19 PM |
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Hi Andrew
On my old 1302 the panel under the fuel tank inside the car got hot to touch. I'm not sure if affected performance as I had no way of checking.
Some old Jags used to run their fuel through jacket containing air hoses, I'm sure how affective this was.
I really think that you have a breather issue with the tank expansion.
Steve
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Jak Rizzo
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| posted on October 28th, 2008 at 04:26 AM |
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That is truely bizarre Andrew!
It deosn't seem right that the hot air from the radiator is heating up the tank though. After 5 laps at Eastern Creek on a 30d+ day, I put my hand
under the radiator up front with the fans on & although the watemp was up to 90d, the air coming off the fans/radiator was really only luke
warm.
On the other hand, I too a few years ago now had that scenario that when I went to fill up with petrol all this air would come rushing out of the
filler cap. I did away with all the elaborate factory breather system & just made a simple fuel ine that goes up & over my dash & out the
left hand side with the speedo cable to the ground. It has never done it again.
Maybe this may help
regards
Jak
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GTMac
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| posted on October 28th, 2008 at 09:01 AM |
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| Quote: | Originally
posted by JVLRacing
shit this is a prob! m8 is there any fuel blowing out of the breather with the tank expanding?
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Have not checked if it was coming out the end of breather. I assume you mean the one that goes through the metal piping then into a flexy and hangs
down near the front beam?
There was fuel sitting in the return pipe and as I said before it spurted out the cap with all the pressure.
Will do another check of all the breather hoses. One thing I will have to check but will replace anyway, is the t-piece I used may not be fuel rated
as its looking a bit crusty and may be leaking or blocked, will replace it with a brass fitting.
Have made a heat shield today anyway which is also going help with getting the air flowing straight under the car.
Drove to work today without the radiator shroud and took a partial kink out of the fuel return hose and no tank expansion. I actually think my tank is
deformed now with big bulge on top, will have to look at someone elses but that will throw the reading out.
Actually Hutcho, is the top of your tank relatively flat.
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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speedster356
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| posted on October 28th, 2008 at 11:38 AM |
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My setup had the radiator exiting into the front under hood area and then out through the inner guards.
The radiator had 2 x thermo fans, behind the front beam I had my 2 x fuel pumps and surge tank which were directly in the radiator exit air flow.
The surge tank, pumps got so hot that the pumps would cavitate resulting in a drop in fuel pressure after quite a few laps on hot days.
The tank got very hot indeed but never built up pressure as you mentioned (vented out through the inner guard, with a high point loop on the
bulkhead).
I moved the pumps and surge tank out of the direct airflow and it seems to have fixed that. The main tank still gets very hot though and the next
thing to do is to duct the exit air out away from the tank.
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Hutcho
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| posted on October 28th, 2008 at 12:43 PM |
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Id also say something is definately blocked. ie your evap line back to the canister. Im not sure what pressure a charcoal canister is supposed to hold
back but I would have thought that if the pressure in your tank is reaching the canister, it would blow it apart.
Yes, my tank is relatively flat except where it tapers up to the filler. If youve found that your tank is cactus, let me know. I may have another one
that will get you out of trouble.
Steve
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GTMac
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| posted on October 28th, 2008 at 08:22 PM |
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Thanks Steve, yes by the looks of my tank compared to yours, its definately been deformed. Mine looks like a coke can that has been left in the
freezer.
OK, at my best will come up with my theory. First thing I found and not happy about. The t-piece that is used for the charcoal canister and the
original breather pipe was supposed to be fuel rated even though its plastic. It looked crusty to me so pulled it off and it broke in my hand and the
internal had melted together thus a complete blockage to both the charcoal cannister and the original breather. Can now remember hearing a hiss as it
must have been leaking out the side of the hose, I thought it was the cap. Bought a brass one from Pirtek today.
Now, why tank so hot, I think one because extra hot day (even though eng temp never above 90d) and two the effectiveness of the shroud. So as I
explained before believe the shroud was directing air more directly onto the tank and as it was hot the thermos cycled more often thus delivering more
heat. Has been good all day today.
Hutcho, let me know when you want to come in for a sticky beak, also the spare tank, is it a fuel inj tank?
1971 Type 3 Fasty - EJ20T
I love 242HP sleepers.
How many sets of lights does it take a $229k Carrera S to learn?
UPDATE: Cayman S, M3, B4 now added to the list. |
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Baja Wes
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| posted on October 29th, 2008 at 01:40 PM |
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Your tank isn't stuffed, it's just been enlarged. You now have a long range tank 
The radiator will heat the tank a lot, you need to shield it well. I have my radiator at the back above the gearbox. When I first built it, I had an
aluminum internal rear radiator / engine cover (under the rear seat / parcel tray). The thermo's pump air across the back of it. At first I just had
internal sound insulation material and carpet over it. In this configuration I had massive amounts of heat coming through the rear seat. It would make
the rear of the car unbareable.
I then took the cover back off and put some aluminum heat shielding material onto the radiator side of the panel. The stuff that is an aluminum foil
with some compressible insulation material on the back (that looks like recycling old clothes or something, see pic below). This fixed my problem and
now hardly any heat comes through into the car. The foil seems to reflect a lot of heat, and the insulation stops the heat getting through to the
actual aluminium shroud / cover panel.
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Hutcho
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| posted on October 30th, 2008 at 08:57 PM |
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At least you found out what it was, mate.
The other tank I have, has been modified with a couple of extra lines.
Ill call you over the next few days.
Steve
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Klaus
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| posted on October 31st, 2008 at 09:41 AM |
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never had any dramas with fuel temp in mine and i'm using orig subi rad and only 1 thermo , on the vapour line back to charcoal canister ( factory
fuel line) I fitted a fuel filter near filler where line is located as i had fuel flowng out of charcoal canister when i parked after a drive , weird
but prob is fixed now . I also have a shroud stopping air flowing into front luggage compartment.
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