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a mate of mine and his brother who are mechanics were extensively looking over my engine the other night planning my turbo conversion ie where his gunna take the water and oil feed etc etc. anyway he pointed out to me someting that i found very interesting, on all rb20's whether det or de there are two small hoses that carry water up to the intake manifold.they run off into the fuel rail and up near the throttle body. They run through what looks like internal galleries in the induction manifold. Anyway they told me that they believe the purpose of this system is to heat the fuel before it is injected into the cylinders. When i asked him the purpose of doing that he said it would be an emission reduction thing and that obviously if we were to remove it then power gains and economy gains are "theoretically possible". I dont believe this can be removed on the dets however because it looks like thats where the water feed for the turbo is, de's just have a welch plug type thing at the firewall side of the manifold.

Iv seen kits for ls1 holdens claiming power gains of like 15 to 20kw by diverting fuel lines etc to bring cooler fuel to the engine. In reality i doubt that it would make that much of a difference but can someone tell me if this theory is correct or not? If so it makes sense that one could expect a couple of kw's from it and a slight increase in fuel economy.

system is easy to disable btw..

let me know if my mates a dickhead or if he might be right? lol

cheers

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i dont know about RB20DE/T's but i know on the RB30 theres a coolant hose running through the plenum and throttlebody. After a bit of a drive the plenum is the same temperature as the coolant etc (esp considering its an alloy it heats up quick) so its heating the air before it gets into the engine, making a CAI fairly pointless.

I dont know about the whole emmisions thing, but i was always told on the r31's it ran through the throttlebody to keep the butterfly from freezing shut...

i removed it and just put a hose in its place when i did my XF tb conversion, does make a bit of a difference to temp, but the plenum does still get warm eventually...

i was actually thinking about it the other day, about getting a really small ish radiator of somsort off something, hooking up some sort of small electric pump and pumping my own coolant through it on a seporate system using the old galleries, (it all started from thinking about heat wrapping etc etc to keep it cold, this seems cheaper and easier) without any sort of thermostat or anything, on a cold day (like a 0degree tassie morning) the engine would be fed a nice cool fresh air, through a nice cool plenum...

Just something i might try one day, its only prob $50 worth of old hoses, cheap tiny s/h radiator and pump...

so by having colder fuel, you get more fuel into the cylinder, and its only a matter of pumping in enough air, right....

oh wait - its the other way around.

I thought that fuel temperature made a difference that is mathematically equal to zero.

the thing is that the colder the air the more air you can get into the cylinder, but the warmer the fuel the better it burns so.... (that is if i remeber right)

therefore if you have a decent CAI it should be set off by a slightly bigger set of injectors to really take effect

(and skitzo - that sounds like an awesome idea)

ok well il ask my mate why he says that colder fuel=more power and post his answer up on here. however he is certainly not the 1st person iv heard sayit.

as for the hose to the throttle body, this must be counterproductive because its heating the air coming into the engine.il do some more research..

zoom did a test on this theroy and made no more power with cold fuel.

thats all, i wouldnt waist my time trying to make the fuel cold, just get rid of the heating through the intake manifold and reap the 0 diference. it mite make a small diference but im sure that it will make no diference

okay....

cold fuel will make no difference to power. There isn't that much thermal expansion...

cold air intake = slightly more air into the cyl.

better intake = more air in.

better exhaust = more air out, so slightly better manifold vaccuum, so more air in.

ever wondered why methanol is used on drag cars? as a fuel, its not the best. It does, however, have a high oxygen content...

Mmmm everyone keeps bringing up the topics about more power.. I would rather see something on improving response.

Its na, how could you really improve response that much. They are pretty responsive as it is.

Get a bigger throttle body, then a smaller press on the pedal will open it up quicker making it seem more responsive.

Its na, how could you really improve response that much. They are pretty responsive as it is.

Get a bigger throttle body, then a smaller press on the pedal will open it up quicker making it seem more responsive.

Interesting..

apparently if u put a 1inch thick spreader plate between ur intake manifold and throttle body it apparantly creates a vacum of sorts and is suppost to make throttle response a lot sharper and snappier

i dont no if this is true but it would be interesting to see

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