Larger Exhaust on a D24 NA?
 

Do D24 NA engines benefit (fuel economy, power) from larger exhausts?

If so, would this work/fit? Or would the header pipe also need to replaced with a larger diameter pipe?
https://www.ipdusa.com/products/2078...lvo-IPD-139511

Seems fairly unlikely it would make a major difference. Maybe a little bit of marginal improvement at the very top of the RPM range when exhaust flow is greatest, but most of us don't spend a whole lot of time running our diesels up at those RPMs.

As noted elsewhere, although there may be a few marginal gains that could be achieved by fully optimizing the NA D24 engine, far and away the greatest performance and economy boost would come from converting to a D24T. If your engine is already out of the car it may be a golden opportunity! Although a good running fresh and healthy D24 can be a pleasing engine to operate as well. But any gain from things like bigger exhaust, overbore, cylinder head work, etc, is going to be at most a percent or two improvement. Probably not enough to even really feel. By contrast, changing to a stock D24T engine in a 240 is a difference you would feel in a huge way.

Forced induction through turbocharging seems to be the unquestioned path to improved engine efficiency and power for diesels..... hence the almost total absence of any non-turbocharged diesels produced by OEMs in modern market, i.e. for the last 30 or so years, outside of agricultural/industrial applications (and even there they are rare). I personally cannot speak to the theory of why diesels benefit so hugely from forced induction (like gas engines also do) yet have relatively little potential for power/efficiency gains through other traditional means that usually have great success in adding power without forced induction on gas engines. By those I mean things aimed at volumetric efficiency, like bigger exhaust, intake, camshafts, cylinder head port/polish, bigger valves, etc. But I would speculate part of it may be that the limited diesel engine speed range, usually topping out at 5k RPM or less, leaves minimal opportunity for taking advantage of upgrades like those mentioned above. A gas engine can spin faster and make use of changes that let it move air in (and exhaust out) more efficiently. And its rev range can be increased almost without limit due to the homogenous charge (air and fuel mixed before entering the cylinder) -- the only limit to engine speed is imposed by what the rotating assembly and valvetrain can withstand, and those too can be modified as budget allows to even let a big-block V8 rev to 8000 rpm or more by use of exotic light/strong metals like titanium..... Meanwhile, a diesel engine by contrast is speed-limited not by inlet/outlet gas flow, but rather as I have always understood it, by the diesel combustion process itself -- how quickly the compression ignition cycle can burn the fuel. And perhaps to some limited degree also by the necessarily heavier mass of diesel pistons/rods/crankshaft that cannot really be lightened much due to the diesel compression/combustion forces they are subject to. So even if you could bolt on a massive exhaust, fancy high-flow intake/exhaust manifolds, and an artfully ported and polished cylinder head with high lift camshaft, you'd never get the engine turning fast enough to create the kind of intake/exhaust airflow rates where those things could really make their difference. At least that's the version of it that makes sense to me.

An exhaust-ing search
 

Hi forumers! A great thread here, thank you.
May I ask a question related to the exhaust system of the d24t?

Can I use the front muffler/silencer from a gasser Volvo 740 (new) on my td car?
Are the d/td muffler any different from what the gassers use(d)?

I have a very hard time finding a setup for my d24t 740 while plenty of options listed for the gasser Volvos.




I removed the entire exhaust system from my car and now I am trying to figure out a proper setup.

Progress is,
Downpipe got cleaned and painted with high heat paint,
Downpipe connector studs at turbo replaced and I am using new copper nuts, flange gasket,
I replaced all rubber hangers and the clamps too along with the bolts and nuts that connect downpipe to the silencer below the glovebox area, new metal sealing 'donut' ring)...
Silencer unit got removed and everything all the way towards the rear end got removed completely.
(Not yet junked except for the rear muffler that rotted out and all piping is toast as well. I kept the front muffler=silencer for now, mainly for reference but the inlet and outlet sides of it are both toast, corrosion and heat ate it up, can not reuse without too much of welding and it would still look bad, dented, and it is probably burnt out. I doubt it can clog but there is residue inside of course lol, blck. )
The rear muffler was a bosal unit (have numbers photographed) and the front silencer was also a bosal unit that says ''volvo 760 turbo- turbodiesel''.


After the removal,

Some experiments followed with the old parts, several variations were tested etc
(downpipe with silencer plus some short pipe
downpipe without silencer with longer pipe
downpipe without silencer but with piping all the way to the back
downpipe with short sidepipes out at the side
downpipe with silencer and short sidepipe out on side
etc)

With mostly all of those experiments, I found the car being too loud for my liking and the power output is literally not changing much no matter what you do.
Maybe the WOT power is a tiny bit better with the all-out straightpipe without the muffler And without the silencer (front muffler)and short piping till appr the rear doors... but it sounded like a dump truck and the vibrations/droning/loudness inside were not pleasant at all.

Also tried removing silencer unit and used rear muffler only but it did drone as well, and it was also loud.



I now prefer the factory setup or something very similar, in look, in size, in length and in routing.


Can I use anything from the gasser (FRONT MUFFLER/SILENCER, REAR MUFFLER)
(yes i know the axle-over pipe and the tailpipe is the same , and i bought those already)

What is the main difference (if any) between the oem gasoline and d/td powered 740 and 760 cars` exhaust system?

Does it really matter what I use? Also, I gotta have both 'mufflers' in NY state, I guess.



MARKINGS ON THE UNITS:


Front silencer unit:


B O S A L
287-947 ALU
EEG-8-84 / 424 - 5303
VOLVO 760 TURBO - TURBO DIESEL


Rear muffler:


B O S A L
235-949 ALU

36 26 NR 6 --this entire line is barely readable, probably not correctly registered!

EEG B (?or 8?) 84/424 5304


NOte: Despite days of searcing, I haven`t seen any silencer units that have a STRAIGHT pipe section like the one I removed, you can see it in my pictures.

This link shows some units and interestingly the cars with different engines share the same rear muffler , AND even the silencer/front muffler. I am confused by this info.)
https://medias-norauto.fr/pdf/Eclate...osal-15784.pdf

Thank you!

What you are calling the front "silencer" I think is referred to as a resonator.

Mine also needs renewing. I did pull one from a gasser at the JY as it looked similar. Probably will mount right up using the same hangers etc. Some differences:

1) Inlet flange is not the same orientation/location to mate up to the D24T DP so will need to be cut somewhere along the straight run and welded to a good piece from D24T section. Might be tricky to maintain the correct angle and geometry.

2) Diameter at the resonator can inlet and outlet appeared to be slightly smaller than the existing one on my car, but the pipe further out appeared to measure out the same. Hard to accurately measure because it is ovalized. Not sure it matters much overall?

Rear muffler and associated over-axle and tailpipe sections appear to be same as gasser.

OTOH a capable muffler shop should be able to fit in a generic resonator and fab up the two ends to mate up with what you have.

For sure use hi-temp anti-seize on the nuts/bolts/studs.

Thank you for the quick response. I found a seller that states the silencer he has fits a td 760. There`s one way to figure out, I plan to meet him in person to compare it to the one on the car (will be tricky). Many other websites also happen to list the very same item for the turbo 760 (6cyl gasser)and the turbodiesel d24t 760. I am not sure they used the same part but who knows? It is very hard to figure it all out. I wish it all just fit without tinkering. The car was a gasser originally so maybe it has all the places for a gasser exhaust and any unit will fit? I have no idea yet.

In the meantime I found this for good reference.
https://www.skandix.de/en/installati...01422/2000332/

There`s no 'good piece' of the rotten d24t silencer section piping that is currently on, so I will need to see what to do with a new unit to achieve a good fit. I really do not want to get into having to weld it (that`s partly why I prefer the stock system which should be plug-and-play plus adding clamps at certain factory places.)

None of the resonator/silencer units I found show the straight section that the d24t page displays.
It looks like that the one I removed is probably an original d24t part, judging from the straight section between downpipe and silencer/resonator.

Shouldn't be too difficult. You can slide the piece up alongside the existing under the car and get a good visual on matching the length, connection locations/angles, and hanger mounts. Should be obvious. *Might* want to jack up that side of the car for easier access so bring your floor jack and stands. Bring tape measure and possible calipers as well.

Doubt that Volvo stamped different floor pans for different engine models. Don't worry about that.

RedArrow, what did you end up going with?

Anyway, I went with a resonator delete, straight pipe section welded in, as replacement front section exhaust parts are apparently NLA.

$90 out the door at a local independent muffler shop.

First impressions are that I can't really tell much of a difference in sound level or quality from stock. Thought I could newly hear a bit more low turbo whine at low speeds.

The old resonator had a good-sized hole in the side of the can where it was blasting out long wispy tails of sooty fiberglass. Snagged on the axle bolts, rear wiper blade, strewn along my path in general. Definite improvement. :)

The problem with most gasser (seeming) equivalents is that they are one size smaller (2" vs. 2-1/4?).

Attachment 2015

Sidenote: Bit of a change in routine for them as they have recently been mostly busy replacing catalytic converters for victims of rampant CC theft in this area.

:mad: :mad:

Common everywhere now seemingly. It is an infuriating problem as the obvious root cause (to me, IMO) is the scrappers buying the stolen goods and providing a market for the thieves. They have to know, don't they? The same guy shows up over and over with cats that were obviously buzzed off in a hurry, and they are happy to buy them each time?

Apparently the vehicles that get hit hardest are pickups and SUVs since they sit higher, the easier for a thief to slide underneath with the sawzall. Thus I have heard it is often someone's business vehicle, a work truck or van, etc that they depend on for their living. Not that that's any worse than someone's commuter vehicle, unfair either way. But maybe one way to avoid it is to drive a regular car instead of a truck or SUV.

I actually just this winter bought an old mid 90s Land Rover as a 4x4 snow beater, cheap, after its PO parked it in downtown Billings and came out to discover the cats were gone. Sounded like a ski boat when I went to see it and start it up with open headers on the old Buick/Rover V8 gas hog. :D But felt terrible for the owners as they had obviously tried to take care of the truck and put a lot into it, and this was the last straw for them. So in some ways the cat theft was a windfall for me since it made the truck worthless ($2000 to get new Y pipe with cats from Rover dealer). Had my local muffler place do some straight pipes in place of the cats since for my purposes this works OK and no emissions testing here of course. It is a miserable reality for folks to face this though. Perhaps good business for the muffler shops.

https://discoweb.org/index.php?attac...768-jpg.63831/

ngoma looks like good work done on yours for $90! My wagon has the same setup. Straight pipe where the front muffler/resonator was, done before I got the car so always been that way. I have never been able to tell that it sounds any different from one with the full factory exhaust.

Actually here most recently the CC thefts have slowed down. Entire car theft has soared. Kia/Hyundai every day (evidently there is a new recall to remedy a "deficiency" in their anti-theft features), Subarus are also popular theft victims, as are '90s Hondas. MOST recently, Ford trucks and vans are most popular, stolen and used to bash into storefronts for further burglary.

Often, when found, these stolen vehicles are trashed with needles, misc. mail, many are deemed hazmat totals, soaked in meth manufacture residues. :eek:

Yeah, indeed on all that. In fact just in my own personal immediate experience, two relatives of mine in the Puget Sound area had cars stolen that way in the last few months. Both of them older Subarus and both with manual transmissions, which really surprised me. I had always heard the saying that the best antitheft system available is a manual transmission, especially in the modern age where some single digit % of drivers on the road know how to operate one. But apparently the crooks have figured out how to get around that.

First was a ~2002 WRX that had been owned by a relative up Avalon Way in W Seattle on the north end. Car he had had forever and competed with in rally events all over WA, OR, BC, so attached to it. Had upgraded engine and differentials, suspension, etc..... Stolen and then found a few days later down on W Marginal somewhere full of drug gear and was totaled as a biohazard, just like you say. He could have bought it back as a salvage and probably replaced the interior and revived it, but was sad enough about it that he decided to give up and move on.

Second was a ~1999 Outback owned by my brother-in-law in Bellingham. Disappeared overnight from the parking lot in his apartment complex right under bright lights! Found a few days later nearby in Fairhaven completely full of computers, cell phones, tools, AND lots of keys to other vehicles. :eek: Fortunately minimal damage to the car itself and he got it back.... And installed a secret fuel pump disable switch in a hard to find location.

Also had a friend get a nice motorcycle stolen in W Seattle in the past year, don't think that one was ever found. Plus as I recall you have had some bike thefts.

Part of what is most unfair about that trend is apparently the thieves have realized older vehicles are easiest to steal, plus they are usually not stealing for the car's value but rather simply as transportation to commit other crimes.... So their targets are often 20yo-plus Subarus and Hondas and the like. Thus the victims are less likely to be folks of means with newer vehicles that are probably covered by comprehensive insurance; instead more likely someone driving an older car with no theft insurance and not with enough cash lying around to easily absorb the loss of a major asset, plus their transportation to work, etc. This was certainly true in one of the two cases above.

It's a mean world eh? :(

Sorry for the thread hijack.

Steering back towards OT-- We D24s don't have to worry about CC theft. :p

So there's that. :D

Yes. And with a long wait for glow plugs on a cold engine in the middle of the night, and very little ability to successfully start cold without the operator knowing to wait for them, hopefully the grand theft auto folks may suffer a little deterrence with our cars too. :p So we can hope that a D24 Volvo, especially one with a manual trans, is fairly low on the chances for being a crime target.

Though one thing I will say on the other hand is I am not sure the CC thieves are necessarily smart enough to know the difference between a cat and a muffler. They can look similar enough without knowledgeable inspection, especially in the dark etc. Plenty of cases I have heard of where folks have come out to discover a muffler sliced off, and sometimes the (harder to access/partially hidden) cats still fortunately sitting intact upstream. Karmic justice for the ignorant thief that wasted his time, and at least a muffler is cheaper to replace, though not any less hassle for the vehicle owner.

I actually knew a guy who had an early 2000s medium duty Isuzu flatbed truck that had the muffler stolen off of it while parked in a business lot two summers ago. An old diesel, so no catalyst, but it did sit nice and high off the ground and had a massive, massive muffler right there in plain view and easy access. The thief probably thought he was about to hit the jackpot when he stole that one. :D :D :D

The CC thieves here seem to target Prius and other similar (hybrid?) as those CCs contain more of the valuable materials. (Probably because of the constant engine start/stop cycles reduce the temperatures the CC requires for efficiency?) Anyway, the low clearance doesn't seem to slow them down much. They travel with fancy floor jacks and weapons and a spotter, can get in and out in less than 3 minutes like NASCAR pit stop. The getaway vehicle has no plates/ dealer plates/ towel over the plates.

What happens if you drive your CC-less Land Rover to a state that requires CC?

Back to OT: I wonder if the Volvo front resonator acts as an expansion chamber? But in a different way that what we commonly see on 2-stroke dirt bikes. More like how some early large stationary generators ran their exhaust into a large brick-lined pit, then out via a smallish outlet pipe (to create a certain calculated amount of backpressure). Main idea is to dampen out the individual exhaust pulse spikes to a more consistent averaged flow to get by with a smaller diameter pipe. Although maybe the turbo modifies the exhaust enough into a more laminar flow anyway?

Interesting. That does add up, I have a few friends with Priuses in CA who have been hit for their catalysts.

I don't think there would be any issue driving my cat-deleted LR into a more restrictive state like WA/OR/CA. AFAIK there are no programs at least currently where they can conduct a roadside emission equipment inspection of a private personal vehicle owned out of state. Though I believe such programs do exist or are coming soon for commercial vehicles, at least in CA, even if they're registered elsewhere.

But if I wanted to register my non-compliant LR in WA for example, in a county with visual and/or emissions inspections, then I am sure I would have a problem. I think even a check engine light is enough to fail.

Makes sense on the expansion chamber concept. Combined with some baffles or packing for even better effect? Anything to take the rapping-type pulses out... Though as you say the turbo does a lot of that. Even a straight piped D24T is a little loud but not completely offensive at least IMHO, since the turbo kind of seems to round off and soften the sound. Whereas an unmuffled NA engine seems to have a lot more rasp/blat/snarl. Might not be that much louder really in terms of db, but the quality of the sound feels harder on the ears.