Outer Limits 4x4 Board

How much better is mandrel exuast over a non mandrel system are they worth the extra cash wat are the pros and cons

cheers

mandrel bends flow soooo much better then press bent ones, press bends create a restriction in the middle of the bend, so a mandrel one will allow your engine to rev more freely

So instead of going a 2.5" mandrel, get a 3" standard bent exhaust....

cooki_monsta wrote:mandrel bends flow soooo much better then press bent ones, press bends create a restriction in the middle of the bend, so a mandrel one will allow your engine to rev more freely

x21

How would a 3" system go on an 2.5l common rail navara

mahooody wrote:How would a 3" system go on an 2.5l common rail navara

I'm in the exhaust game and have been told that an exhaust that is to open, when fitted to common rail navara causes issues with the engine management as the extra air flow upsets the air flo meter etc. Any one that tells u that they have a 3' system on one that doesn't play up is either telling porky pies or their system probably doesn't flow that well.

Would a standard bent system be good or should I get mandrel

A standard bent system is perfectly fine. Mandrels do flow better, but they are not worth the extra cost unless you are chasing every last kw.

Anyone got any actual numbers on restriction and flow?

I am 100% sure mandrel bends flow better but I am also 99% sure it makes fark all real difference Some good numbers would convince me otherwise though.

Had a 2007 hilux that we chipped then dyno'd. Two months later we did a 3" mandrel and re-dyno'd. Gained 7Kw (approx 9%) from the exhaust, but that's with a chip also so you'd get more benefit over non chipped.

Careful of mild steel mandrel bent exhausts where all the bends are welded in. On a 4x4 that seen mild beach work, mine was rusted out within 2 years.

I would say on a high performance engine go Mandrel bend...

in a shit powered 3ton 4wd, i wouldnt think it would make a difference.

from my talkings with several exhaust shops, mandrel adds very little over press bent on a diesel 4wd. 3 shops have told me you lose just as much flow having a muffler as you do having press bends in say a 3 inch exhaust on a patrol.

also, the big exhausts do cause issues with SOME computers so be careful. at the same time a 2.5 navara does not need 3 inch and it wont offer much benefit over a 2.5 or 2 3/4 exhaust. just think, on 700hp supras and skylines alot still run 3 inch exhausts right through, some which rev out to 9000 or 10000rpm that will produce ALOT more waste gas then a soot bucket 4 litre diesel.

Another thing to keep in mind is the restriction of those braided flex joints, they are corrugated on the inside causing massive airflow interruption... I was discussing this with a mech-engineer at work and by his calculations, depending on the length of the flex joint, you can reasonable expect the flow through a 3" flex to be reduced to around 2 - 2¼"

Ruffy wrote:Had a 2007 hilux that we chipped then dyno'd. Two months later we did a 3" mandrel and re-dyno'd. Gained 7Kw (approx 9%) from the exhaust, but that's with a chip also so you'd get more benefit over non chipped.

But was the old exhaust also 3"? Or did you up the size at the same time as you went with mandrel bends?

Nominal Pipe Diameter
Press Bent Area (Square Inches)
Mandrel Bent Area (Square Inches)
2.25" 2.74 / 3.13 3.92
2.5" 3.43 / 3.92 4.90
3" 4.94 / 5.65 7.06


thats from the beaudesert exhaust site and assuming it is accurate
on a 3" system a mandrel bend will flow minimum 25% better, maximum 43% better than a press bend.

that is assuming that your car needs the 3 inches of flow. most dont need it

chunderlicious wrote:that is assuming that your car needs the 3 inches of flow. most dont need it

yeh, but if your car has a 2.5" press bent system, then your possibly flowing half that of a mandrel 3" system.

I dont understand how a turbo diesel can suffer from having too big an exhaust.

these navaras etc, do they have an o2 sensor in the exhaust or somthing?

these navaras etc, do they have an o2 sensor in the exhaust or somthing?

If there anything like the current landcruiser's they'll have several...

I know that aftermarket exhausts do casue probs on new diesel Hilux's and Landcruisers. BIIIIIG losses in power! Big.

Shadow wrote:

chunderlicious wrote:that is assuming that your car needs the 3 inches of flow. most dont need it

yeh, but if your car has a 2.5" press bent system, then your possibly flowing half that of a mandrel 3" system.

I dont understand how a turbo diesel can suffer from having too big an exhaust.

these navaras etc, do they have an o2 sensor in the exhaust or somthing?

alot do have oxy sensors in the back end.

im not saying they will suffer from having a big exhaust, just saying the extra expense isnt always needed.

mike_nofx wrote:So instead of going a 2.5" mandrel, get a 3" standard bent exhaust....

Yep, agree with this, a long time ago (late 90's) the Zoom magazine did a test on this and that was the outcome they got, that was with flow tests etc, even with a mandrel bent 3" system the biggest restriction was mufflers/cats etc, so the conclusion they had was to get a pres bent 3" over a mandrel 2.75" or 2.5" etc

Of course if money is no object, then its a differnt matter. Also depends on what can be made to fit in the space available.

phat-customs wrote:

these navaras etc, do they have an o2 sensor in the exhaust or somthing?

If there anything like the current landcruiser's they'll have several...

I know that aftermarket exhausts do casue probs on new diesel Hilux's and Landcruisers. BIIIIIG losses in power! Big.

I've fitted plenty of exhausts to new model Hiluxs and even a 200 series and had no issues at all.

my brothers got a beaugeseart 3" exhaust on his v8 TD cruiser ute and has not lost any power?

The current Hiluxs run no sensors in the exhaust, and I don't remember any in the 200 series either.