Effects on boost with distance it travels
Turbo Mini Forums

How is the boost effected if it has to travel a longer than usual route?
I guess you get more lag and slightly less boost at the plenum?
Can you fit a larger turbo to compensate?

Sorry, Im sure this has been covered before but I cant find it

Paul

I seriously doubt it!

yes , long inlet from turbo should cause more lag as it takes longer to pressurise , but once up to pressure it will /should make same boost as a short tract.

carl

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Do sharp bends cause pressure loss? Is this how the restrictor in standard plenum works?

If something is worth doing, it's worth doing half of.

In theory yes. In practise I doubt you'd notice any difference.

Supposedly each 90 degree bend in charge piping is equal to a 1psi pressure loss.

Supposedly! I have not got any personal data to back this up it's something I have read a few times. Once on here I think.

If this theory is correct then you, potentially, could run without a restrictor and have the float bowl pressurized by the point in the charge piping that is around 3-4psi higher than the carb mouth sees.

I know Richard had all sorts of issues with his fuelling when he was taking the boost signal from the turbo as opposed to the plenum, which suggest that there's a noticeable drop in pressure.

like tom say in theory yes. I would think from the cars i've been in if you get the correct turbo some times there is almost no lag.

Best 1/4 mile 13.2 seconds @116 mph
First 5 port miniturbo to make over 200 bhp on a carb?
First 5 port miniturbo to make over 200 bhp on Injection?

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do a we bit o maths, how much volume is contained within a large hose run. how much air is cunsumed by your engine at x rpm. from this you can work out how long it will take to compeltely replace all the air in the pipes. this is the time that will add to lag :)

usually neglegable. :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

As above, yes, but you'll never get too much pipe or too big an IC under a mini bonet.

I usually use 2 to 3psi loss in my calculations when looking at comp maps.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

I seriously doubt it!

surely you cant loose pressure over a length of pipeing unless its leaking.

true, but it is leaking, through the valves, into the cylinders then out the exhaust.

Think of bends and the IC as a restriction. Forcing air through the restriction causes a loss in pressure.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

now i can understand that. i was thinking of 8psi of boost signal at the carb rather than at the turbo outlet. as the signal is taken from the turbo outlet the rectriction would push back against the turbo telling the actuator that theres 8psi there. whereas the carb may only be seeing 6psi.

if this is right then you dont loose pressure, you gain signal.

correct?

Edited by MONSTER HEDGEHOG on 17th Dec, 2009.

if your contemplating rear mounting the turbo, this will add a fair bit of lag, but due to the exhaust side of things more than the air side of things.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

If you are thinking of mounting the intercooler in the boot this is problematic due to ram air. If you really are struggling for space look for a charge cooler solution.

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A man without a project is like a like a woman without a shopping list.

Not looking at the back of the car, Im just thinking of hiding it all under the wings with a charge cooler so I can keep a MK1 looking engine bay and make my own plenum that looks like a standard tin air filter.

Paul

I seriously doubt it!

SNEAKY!!!

Pressure loss is a function of the square of the velocity. Halve the velocity and you get a quarter of the pressure loss.

Bends make the biggest loss.

So just make the pipes a tad bigger and minimise the bends and the drop in boost will be negligable.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Not sneaky Nic, Id say classy (if it works)

To complete the look, I really am teased with trying to use twin carbs. My imagination went wild and I even started thinking of a turbo for each carb.

Im finding it very difficult to decide what I want to build but I do know I want turbo for the daily drive MK1

I seriously doubt it!

I'd like to see a twin su turbo.

Could you seal an HS?

If something is worth doing, it's worth doing half of.

Im sure I could find something to seal it off another carb or TB

I seriously doubt it!

Do it!

If something is worth doing, it's worth doing half of.