khaos
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I thought I would spark a load of sarcastic comments but I'm glad to see I started a serious intellectual discussion 
Just a random question that will make me sound stupid.
- Thread starter khaos
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There's a hell of a lot to manifold design peeps, and I aint no expert!!!!
ratty
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oldskool
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If the water is up to your bonnet then yes you will fill the exhaust and the engine with water, if the water is only up to the rear silencer then it will only fill up as far as the bend where it goes over the axle if memory serves me correctly thats quite high.
As for sucking water up the exhaust unlikly, you do get a bit of suck from the exhaust when starting (cranking) but you get a lot more blow.
Im sure that if it was a problem or a concern some of the off roaders on LZ would have fitted exhaust stacks to there landys.
bobbler
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does it not just boil down to the same reason we use wading plugs and extended breathers (hot versus cold senario)?
when something hot (engine) goes into something cold (water) the water will be sucked in or something like that at least with the engine running the water will be pushed out by the exhaust gasses.
Not a very technical description i know but it is still early for me
when something hot (engine) goes into something cold (water) the water will be sucked in or something like that
at least with the engine running the water will be pushed out by the exhaust gasses.Not a very technical description i know but it is still early for me
rustyrhinos
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You are right, a bore that is too big for the car can decrease performance. But that does not quite mean that cars need the back pressure itself.
Yes, but as to not confuse people, it does not mean that exhaust gases can always leave quicker because the bore is bigger...not saying that engines like back pressure though. Just that because engines do not need back pressure as such, that does not mean it makes sense to do your best to reduce back pressure (i.e big bore or short exhaust)
They do not need the back pressure as such...but that in turn does not mean the bigger the bore the better...because you get to a certain bore size where the pulsing effect off the exhaust gases cannot happen correctly.
It also does not mean that on Turbo cars the bigger the bore the better. Turbo cars generally have a higher flow (or pulsing pressure) than n/a cars. But that is not to say that the bigger the bore the better, because you still need to right size for pulsing to occur.
So why do some race/drag cars not have a long exhaust like a road car then? Different rules apply for very high output running just headers for instance...but a low boost, low RPM pressure, Land Rover Diesel turbo engine is not! So still needs a matched bore, not just the biggest.
oldskool
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Quote:
back pressure is key to the smooth running of most injuns.Makes ya laff wen ya see chavy types with big bore exhuasts that probbaly rob 5 or ten horse power
You are right, a bore that is too big for the car can decrease performance. But that does not quite mean that cars need the back pressure itself.
Quote:
The FACT is no engine likes back preasure, thats a fact, the quicker the gas can leave the engine the quicker the air and fuel can get in, giving better higher rev range performance,
Yes, but as to not confuse people, it does not mean that exhaust gases can always leave quicker because the bore is bigger...not saying that engines like back pressure though. Just that because engines do not need back pressure as such, that does not mean it makes sense to do your best to reduce back pressure (i.e big bore or short exhaust)
Thats true the pipes have to be the correct size to small=high back preasure to large=slower gas speed which if the primary pipes are to short causes the gas to stall and get sucked back into the cylinder, for that same reason you dont have cyl 1 and 3 (on a 4 cyl engine with firing order of 1,3,4,2) going to the same collector also the primary pipe must be the same length.:biggrin1:
Quote:
No engines need it and one of the causes of it on a t/c engine is the turbo its self.
They do not need the back pressure as such...but that in turn does not mean the bigger the bore the better...because you get to a certain bore size where the pulsing effect off the exhaust gases cannot happen correctly.
It also does not mean that on Turbo cars the bigger the bore the better. Turbo cars generally have a higher flow (or pulsing pressure) than n/a cars. But that is not to say that the bigger the bore the better, because you still need to right size for pulsing to occur.
So why do some race/drag cars not have a long exhaust like a road car then? Different rules apply for very high output running just headers for instance...but a low boost, low RPM pressure, Land Rover Diesel turbo engine is not! So still needs a matched bore, not just the biggest.
back pressure is key to the smooth running of most injuns.Makes ya laff wen ya see chavy types with big bore exhuasts that probbaly rob 5 or ten horse power
You are right, a bore that is too big for the car can decrease performance. But that does not quite mean that cars need the back pressure itself.
Quote:
The FACT is no engine likes back preasure, thats a fact, the quicker the gas can leave the engine the quicker the air and fuel can get in, giving better higher rev range performance,
Yes, but as to not confuse people, it does not mean that exhaust gases can always leave quicker because the bore is bigger...not saying that engines like back pressure though. Just that because engines do not need back pressure as such, that does not mean it makes sense to do your best to reduce back pressure (i.e big bore or short exhaust)
Thats true the pipes have to be the correct size to small=high back preasure to large=slower gas speed which if the primary pipes are to short causes the gas to stall and get sucked back into the cylinder, for that same reason you dont have cyl 1 and 3 (on a 4 cyl engine with firing order of 1,3,4,2) going to the same collector also the primary pipe must be the same length.:biggrin1:
Quote:
No engines need it and one of the causes of it on a t/c engine is the turbo its self.
They do not need the back pressure as such...but that in turn does not mean the bigger the bore the better...because you get to a certain bore size where the pulsing effect off the exhaust gases cannot happen correctly.
It also does not mean that on Turbo cars the bigger the bore the better. Turbo cars generally have a higher flow (or pulsing pressure) than n/a cars. But that is not to say that the bigger the bore the better, because you still need to right size for pulsing to occur.
So why do some race/drag cars not have a long exhaust like a road car then? Different rules apply for very high output running just headers for instance...but a low boost, low RPM pressure, Land Rover Diesel turbo engine is not! So still needs a matched bore, not just the biggest.
rustyrhinos
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Glad someone agrees! Especially when it is mostly different to what everyone has said hehe.
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