how much suck

Post by **AdrianGQ** » Wed Feb 15, 2006 6:26 pm

i had a search but couldn't find what sort of cfm a td42 would be flowing in standard form and dose anyone know how much there turboed engines are flowing thanks

Post by **fnqcairns** » Wed Feb 15, 2006 11:02 pm

Hi Adrian I might be able to help a bit

, a 4.2L diesel takes in 4.2L of air every 2 revolutions of the crankshaft. So at 6000rpm the engine displaces 6000/2 x 4.2 =12600L of air per minute. 12600L per minute = 445cfm at 6000rpm.
So if I have it right so far each 1000rpm = approx 74cfm.

Small changes in cfm will occur with temperature and I would suspect a turbo which cannot change the capacity of the engine (4.2L every 2 revs) if boosted high enough may increase cfm because of the extra air charge stuffed in by up to 20% or so but thats a huge guess on my part I really do not know.

I am no math guru just thought I would give it a go because I own one myself and am planning to make a SS snorkel, very happy to be shown wrong.

Would be interested to know what the real known numbers are if anyone has them.

cheers fnq

Post by **CRUSHU** » Thu Feb 16, 2006 7:00 am

Atmospheric pressure is 14psi..... so if you were running 14psi boost, you have effectivly doubled the cubic inches of the engine, eg 8.4l
so if you were running 7psi (pretty normal) 6.3l

so you would have to supply enough air to feed a 6.3l engine, at the revs required.
i assume you are building a snorkle? you will need to go bigger than the required size, as the bends reduce flow, so the smallest part of the intake or snorkle will need to supply the required amount of air, at least.

i believe a 4" snorkle is good for a 4.2 td...

Post by **AdrianGQ** » Thu Feb 16, 2006 4:10 pm

yes snorkel will be coming soon in 4" but also researching for a water to air intercooler to work out size and so on

Post by **turps** » Thu Feb 16, 2006 6:40 pm

AdrianGQ wrote:yes snorkel will be coming soon in 4" but also researching for a water to air intercooler to work out size and so on

Well Nudge you know the rules get enough stainless to make me one to pls.

Post by **Juzza** » Thu Feb 16, 2006 9:15 pm

turps wrote:
AdrianGQ wrote:yes snorkel will be coming soon in 4" but also researching for a water to air intercooler to work out size and so on
Well Nudge you know the rules get enough stainless to make me one to pls.

You pair know stainless is too heavy........

Post by **turps** » Thu Feb 16, 2006 9:28 pm

Juzza wrote:
turps wrote:
AdrianGQ wrote:yes snorkel will be coming soon in 4" but also researching for a water to air intercooler to work out size and so on
Well Nudge you know the rules get enough stainless to make me one to pls.
You pair know stainless is too heavy........

Then what are all the cool kids using these days mister Justin. mmm Aluminium wonder how much that is.

Post by **fnqcairns** » Thu Feb 16, 2006 9:29 pm

Make that a trio, I was planning on a stainless myself useing exhaust pipe.
Is that too heavy as well?

cheers fnq

Post by **meiamaro** » Thu Feb 16, 2006 9:41 pm

I notice with my turbo TD42 that when sitting at lights she pulls
away ok, but at 60+kph she seams more responsive.
would this be the ram air effect maybe?
And would a "custom" 4" snorkle improve it?
I also noticed that Trent Leen's OBC patrol has a "normal" snokle, yet he does'nt
seem to lack power.

Cheers Ian.

Post by **AdrianGQ** » Fri Feb 17, 2006 11:55 am

just got quoted $40 per meter for 4" pollished stainless tube is that any good $135 for 700mm of 75mm aluminium round bar so hand over the money turps

Post by **fnqcairns** » Fri Feb 17, 2006 1:12 pm

i believe a 4" snorkle is good for a 4.2 td...

Bloody hell that pipe size looks large on a road car!

It seems all accesories are either made to suit 3" or 4". 3.5" would be ideal just hard to find snorkel heads, precleaners and underbonnet air cleaner boxes that will bolt straight up.

still searching but I may need to settle with 3" SS.

cheers fnq

Post by **fnqcairns** » Fri Feb 17, 2006 1:38 pm

Ian at 60kph+ your turbo is spun up and ready in quicktime should you need boost.

The only true way too see if the 4 inch would work for you is to fit one but with such a big hole in the guard it's hard to go back to the plastic one if it made no difference.

If I find someone who can do quality tight bends in SS pipe here in Cairns I will let you know, no-one does mandrel bends up here, I have already checked around.

cheers fnq

Post by **JemmyBubbles** » Fri Feb 17, 2006 2:10 pm

Use Rubber bends from a truck joint.

That way it still looks shiny without being tooo shiny. If it looks too shiny then you not hardcore enuff. LOL

Wouldn't you be buying pre(made) mandrel bends and cutting/shutting as you go along anyway ? Aren't these available from an exhaust joint.

Rubber bends are handy especially if you like to rub up against trees... like me. Simply replace the bent section.

Post by **fnqcairns** » Fri Feb 17, 2006 2:59 pm

I want one like choppers green machine here:

http://www.outerlimits4x4.com/PHP_Modul ... 34&start=0

Looks like 3" to me?

cheers fnq

Post by **turps** » Fri Feb 17, 2006 6:38 pm

AdrianGQ wrote:just got quoted $40 per meter for 4" pollished stainless tube is that any good $135 for 700mm of 75mm aluminium round bar so hand over the money turps

Geez that was abit quick for me. Wait till I finish spending abit of money on other stuff. And for a 1/3 the cost I think S/S is the go. But I still wanna know what Justin is offering for another option.

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