Fuel Heat Exchanges on 5.0 V8

[92 VP SS]

Hi has anyone noticed, that the 5.0 v8 appears to have a factory fuel heat exchange system under the what I thought were cosmetic engine covers. I actually think they hold the heat onto the fuel rail.

Both fuel rails have engine coolant hoses running along them that are held into place and covered by the covers. Also the front tube has a coolant hose running along it and is covered as well.

The system reminds me of the heat exchanger modifications that people sell to increase economy.

Anyway just curious to know if anyone else has thought this ?

[Morton]

The heater hoses run along the top of the manifold because there is nowhere else to put them, and the heat sinks on the fuel rails are there to help mantain the fuel temperature at a cooler level.

[mr calais 5.0]

thought heat sinks were there to draw the heat away?

[92 VP SS]

It seems to me holden are doing a good job of keeping those rails hot. Next time you have your fuel rail covers off check it out. A heated coolant line runs past the two main rails and the fuel rail joining pipe. Also the covers cover the rails and engine coolant tubes pushing the tubes against the rail and shelding them from the heat escaping..
I figure holden must of done it this way for a reason as the coolant hoses could of been run on top of the fuel rail covers if they wanted the rails to be cooler.

[VN_Luke]

i don't know whether hot/cold fuel is better for economy (or whether it makes a difference), but it does stand to reason that it would be beneficial to maintain a consistent fuel temperature when you have no method of compensation for variance in said temperature.

so I guess what I'm getting at is; according to me, there would be minimal difference in economy/power whether the fuel is hot, or cold. However - because there is no way the ECU can tell what temperature it *actually* is, the tune will be most efficient when the temperature is constant and closest to what it was originally tuned at.

[mr calais 5.0]

They might be there for looks and just to cover up hoses and rails..

[Reaper]

i don't know whether hot/cold fuel is better for economy (or whether it makes a difference), but it does stand to reason that it would be beneficial to maintain a consistent fuel temperature when you have no method of compensation for variance in said temperature.

so I guess what I'm getting at is; according to me, there would be minimal difference in economy/power whether the fuel is hot, or cold. However - because there is no way the ECU can tell what temperature it *actually* is, the tune will be most efficient when the temperature is constant and closest to what it was originally tuned at.

Warmer fuel will generally atomize better whilst you want cold air for power. The only time you would need to warm the fuel is on cold engine start up on a freezing cold morning. The stock Holden banana manifold is terrible when it comes to air temp as it sucks the air down into the valley which is pretty much the worst place you can get for a heat soak from the motor. As for the fuel runners - I think it's more as Morton posted - they have the heater hoses there as there was no other place to run them.


Reaper