OK, if you want to play the semantics game let's get really techincal. I should have said "no additional constriction". All bends restrict airflow in the sense that the change in direction slows down the air stream and interrupts the laminar flow. Thanks for pointing out the obvious. The point you're having a hard time accepting is that you were wrong about the bends being a significant constriction due to the diameter reduction from non-mandrel bends. But that isn't the case - like I said, they aren't mandrel bends, but they are about as close as you're going to get without a mandrel bending machine.

Sorry dude, but you are wrong. A single 2.5" exhaust isn't even enough for a 400 HP gasoline engine (Mr. Vissard's formulas prove it - 2.2cfm x 400HP=880cfm and 880cfm/115cfm per square inch = 7.65 square inches - slightly more than the area of a 3" exhaust). Even if it were enough for a gasser it would still definitely NOT be adequate on a diesel. I'd be extremely surprised if you could even get a 3L diesel's output up to 400 HP if you're choking the exhaust down to 2.5".

Even the 6.9 Fords (170 HP) came with an exhaust system comprised of two 2.25" down pipes that Y in to a single 2.5" - and it SUCKED!I know they are over twice the displacement of the 3L, but they are also less than half the 400HP 3L you refer to. Simply upsizing the downpipes to 2.5" and everything after the Y to 3" made a HUGE difference on my first F250 diesel, and it wasn't even a turbo! Just changing the exhaust I picked up around 10-15 HP.

My current F250 with the aftermarket Banks turbo system has two 2.5" downpipes to a 3" Y up-pipe, and a 3" pipe from the turbo back, and that's way too restrictive IMO. Even though the non-wastegated turbo only makes around 8 PSI at 3000 RPMs with your foot on the floor and pulling a load uphill. I wish there were room between the bellhousing and firewall to put a 4" pipe from the turbo back and I'd do that upgrade in a hearbeat.

Unfortunately you have to "roll" the tranny tunnel seam on the firewall just to get the 3" in there, so a 4" pipe just ain't in the cards...

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

Not semantics, fact.



Nope, you are. On a NA gasoline burner, a 3" pipe wouldn't be sufficient. On a intercooled, turbocharged 3 or 4 liter engine, its more than fine. Look at anu Grand National, Ford SVO, ect that makes power. A large Ford V8 TD engine that you pappen to used to mess with isn't valid in either discussion.

__________________
1987 SDL. The best there ever was.

well i got some money now and im going to do this too... so the flex pipe that comes right after the turbo looks like it would be ok to start the 3 inch piping right after that all the way to the back of the car

btw i blew in a short coffee mixer straw one that is perfectly round and tiny in diameter and a regular size big straw and the big straw was still easier to blow thru. i think this will work, plus my exhaust is crap right now anyway so i need somthing new and clean anyway, plus when i upgrade to a bigger turbo whether it be now or later this will be a good thing to have anyway

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1985 mercedes benz 300D turbo diesel
1998 VW GTI VR6
1996 VW GTI 2.0
1999 saab 9-3 turbo
1987 300sdl (sold)

You can go to 3" right after the flex, but I figure if I'm going that far, why not get the piece of 3" flex off eBay ($27) and another 3" elbow (which I already have) and go all the way to the turbo outlet?

I knocked off one of the other projects that needed to be completed first before I tackle this. I'll knock off another one or two tomorrow - then when the flex I ordered from eBay gets here next week I should be just about ready to go ahead with this...

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

I would recommend going the extra $50 and putting in a 3" downpipe if your exhaust is already shot. The stock "flex" pipe is a POS design in my opinion.

3" 90* mandrel-$10ish x2
3" flex pipe-$30ish

__________________
$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Ditto - for 40-50 bucks it seems silly to stop short of doing the whole job...

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

We won't have to worry about it since no one is anywhere close to that power...


A true 2.5" exhaust will be more than fine for any power level that can be achieved with the timing chain eaters or the OM617's.... Which is what I've been saying all along..

__________________
1987 SDL. The best there ever was.

Flexpipe = horse shat.


PS

Your caps lock called, it needs a rest...

__________________
1987 SDL. The best there ever was.

The catalytic converter on my '87 has no clogged holes, flows well. Mercedes installed as part of the 50-state trap-ox replacement campaign many years ago.

__________________

Gone to the dark side

- Jeff

Any up dates on this.

Not from me at this point. As I said earlier, I had (and still have) a couple of other projects that have pushed this to the back burner. They are "need to do" whereas this is only "want to do"...

I don't anticipate having the time to do anything on this until spring - at least. Maybe early summer...

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

im still planning on doing this for sure but im going to wait til my garage floor isnt
100 degrees below zero. i hate working on a cold garage floor, and even worse when ur trying to get a rusted ass exhaust clamp or bolt off and it breaks when ur about to give urself a hurnea from using so much force to try to break it loose and u smash ur knuckles against the super cold metal.

__________________
1985 mercedes benz 300D turbo diesel
1998 VW GTI VR6
1996 VW GTI 2.0
1999 saab 9-3 turbo
1987 300sdl (sold)

HAH! At least you have a garage to work in. I'm doing a diesel transplant into a Jeep Cherokee in my driveway with a "tarp-garage" set up to keep the rain off me! And it rains all the frigging time around here this time of year...

Oh well, at least the temps are in the 40's...

__________________
1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown

Haha, the joys huh? Gotta love EL Nino!

__________________
Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

Try gravel and mud out doors. You might better appreciate you horrible working conditions.

Consider a good kerosene bullet heater. Deflect the out put toward the floor with a piece of steel, and the floor is heated.

One word. Smoke Wrench. It has to be the greatest tool a shade tree mechanic can have. Not only does it give you heat to loosen bolts, but you can cut off rusted old clamps and exhaust parts.

__________________
85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.