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+--- Thread: 617 exhaust manifold bad idea..? (/showthread.php?tid=7217)
617 exhaust manifold bad idea..? - PanicButton - 05-18-2016
Hey guys, been stalking for years, and I'm always impressed with the depth of knowledge that finds its way here. Rarely has someone not answered my questions already. But im currently wrapping up a fairly thorough rebuild with a number of modifications done.. prechamers modified(differently than others have), aggressive port & polish, shaped cylinder faces, n/a intake, vnt turbo, 261 nozzles, a/w intercooler are the big ones. Also using flat plate heat exchangers for oil, trans, tcase coolers just for kicks. Might even use another fphe in place of the A/C evaporator and plumb it in with my intercooler water to go below ambient. Pump is stock but cranked, deciding whether to farm out the IP or attempt to swap elements myself since I have the spare then just have it tuned locally, but the plan is for more fuel. Maybe meth injection too, undecided. Using a HD 3 speed auto trans with a high stall torque converter to let the turbo spool a little before putting load on the engine. Anyway, not the point, just a little background, not the biggest but still a decently involved build. So it's going in a yj wrangler and I have a planetary tcase doubler so I can use that as an underdrive to utilize the high rpm range off road. My ultimate goal is torque, I don't care much how quick she goes, I just want some decent love at low speeds. So Ive got this 617 n/a exhaust manifold that isnt doing anything, I've got plenty of room in my engine compartment to screw around, basically I'm wondering if I were to weld a flange on to accept a t3 turbo, do you think I'd see any benefits?? EGR port even looks like a perfect location to weld in a bung for a egt probe. Sure looks like it ought to flow better to me, little better off boost response maybe? Even if only slight, it'd be worth it to me to do it, plenty of free time. This is being compared to the stock turbo EGR manifold, my other option. I don't believe it's been done yet, but any input would be enormously appreciated, even if you're just spitballin or throwing out wild ideas, it's all helpful. Thanks!
Once this sucker comes together over the summer I'll put together a build thread.
RE: 617 exhaust manifold bad idea..? - NZScott - 05-18-2016
Not ideal, but people do it. Many LD28 turbo conversions use a J pipe on the stock manifold to chuck the turbo on, rather than find a L28 turbo manifold. If you have a stock turbo manifold, I'd say stick with that for torque - shorter path to the turbo I think would help with spool up which you'd want for torque.
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-18-2016
There's a mess of turbulence in the stock turbo manifold, especially EGR deleted. If pressurized air acts anything like water under pressure, then that N/A manifold would move significantly more than the turbo manifold just being that the flow isn't being obstructed by conflicting pathways. Plus it's coming out in pulses to boot, wouldn't it be more ideal to keep the flow separate until it can be converged on as parallel a path as possible? You may be right, there's probably a reason MB designed the manifolds the way they had, but my limited reasoning skills keep trying to find the advantages to the turbo manifold and best I can figure.. maybe limited space? Most aftermarket turbo headers for example resemble the N/A manifold by design much more closely than the turbo one.
RE: 617 exhaust manifold bad idea..? - Alec300SD - 05-19-2016
(05-18-2016, 09:58 PM)PanicButton There's a mess of turbulence in the stock turbo manifold, especially EGR deleted. If pressurized air acts anything like water under pressure, then that N/A manifold would move significantly more than the turbo manifold just being that the flow isn't being obstructed by conflicting pathways. Plus it's coming out in pulses to boot, wouldn't it be more ideal to keep the flow separate until it can be converged on as parallel a path as possible? You may be right, there's probably a reason MB designed the manifolds the way they had, but my limited reasoning skills keep trying to find the advantages to the turbo manifold and best I can figure.. maybe limited space? Most aftermarket turbo headers for example resemble the N/A manifold by design much more closely than the turbo one.
Even though the exhaust tubes on the NA exhaust manifold are longer, the collection point is narrow and would probably diminish the flow as a result. It could be modded, but it seems like a bit of work.
If you source an early stock non-EGR turbo exhaust manifold (1978-80 300SD 116.120) I think you'll be happier with the result. It has better flow than than a blocked-EGR manifold, it has the standard T-3 mount and bolts right up to any OM617. The pyrometer probe (and exhaust pressure probe - if desired) can be mounted pre-turbo.
See post eleven on the linked thread for photos of my modded manifold and follow the links in that post for more info. http://www.superturbodiesel.com/std/showthread.php?tid=7069
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-19-2016
Not to be an ass here, but thats not true.
T3: 1.83" x 2.34" = 4.28 Sq. Inches
2.5" circular: 3.14 × (1.25x1.25) = 4.91 Sq. Inches
So you see, the N/A manifold actually is about 13% wider, making the t3 flange the bottleneck. So if I were to just lay down some puddles on the inside of the flange, I could even blend it in fairly easily for a nice smooth transition. The more I'm looking at this, the less sense the turbo manifold is making to me. I wonder if it even is in actuality less volume than the n/a too. Theres a lot of open space in there. Almost seems like it may be a trick of the eye, they could be similar, or at least not far off. I'm going to fill em both up with water and find out for certain.
RE: 617 exhaust manifold bad idea..? - DeliveryValve - 05-19-2016
I always thought that particular N/A manifold would be perfect to modify to accept a turbo. Cut off the end, cut a side hold for the flange and weld it all on. But it's the welding on Cast Iron that concerns me. I do believe if done right, that modified N/A manifold will beat the snot out of the non-egr or egr turbo manifold at any RPM.
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RE: 617 exhaust manifold bad idea..? - Edian727 - 05-19-2016
i do believe the reason the turbo manifolds were made that way was for 1 back then it was commonly thought that boosted engine flow was not(or less in reality) a concern, 2 the n/a engine were lacking in power hence the need and want for good tuned manifolds, will the turbo was not lacking in power, and 3 it had to fit in a particular area, that always a design concern.
I agree that the n/a manifo9ld will flow more. It is commonly know that the n/a intake manifolds way out perform the turbo manifold. to be honest though i doubt you'd see much power gain from the manifold change on a stock engine. Im not implying yo9ur gonna stay sock, and i sure hope you don't
RE: 617 exhaust manifold bad idea..? - NZScott - 05-19-2016
Well, live and learn
I have a spare NA header... hmmmmm....
RE: 617 exhaust manifold bad idea..? - Simpler=Better - 05-19-2016
Cutting & welding a NA manifold is the easiest way to get a "fancy header style exhaust".
/shameless plug for my leftover els($3/pop I've got 1.5" and 1.25"") (I'm out of flanges)
RE: 617 exhaust manifold bad idea..? - Alec300SD - 05-19-2016
(05-19-2016, 01:44 PM)PanicButton Not to be an ass here, but thats not true.
T3: 1.83" x 2.34" = 4.28 Sq. Inches
2.5" circular: 3.14 × (1.25x1.25) = 4.91 Sq. Inches
So you see, the N/A manifold actually is about 13% wider, making the t3 flange the bottleneck. So if I were to just lay down some puddles on the inside of the flange, I could even blend it in fairly easily for a nice smooth transition. The more I'm looking at this, the less sense the turbo manifold is making to me. I wonder if it even is in actuality less volume than the n/a too. Theres a lot of open space in there. Almost seems like it may be a trick of the eye, they could be similar, or at least not far off. I'm going to fill em both up with water and find out for certain.
No offense taken.
I was not trying to dissuade you from proceeding. Just offering my thoughts and another simple option to consider for future readers of this thread.What I was trying to relay was that the collection chamber of the NA manifold looks narrower than that of the stock EGR turbo and stock non-EGR turbo exhaust manifolds. The neck and throat look narrower. This I believe would cause some turbulent flow, less laminar flow, and a slowing of exhaust gas velocity.
Longer, more equal length exhaust runners should help equalize the exhaust back pressure on the exhaust valves and give better engine response. But longer runners will also slow the exhaust gas velocity from the longer path and the greater radiant heat loss as well.
This is not to say a NA exhaust manifold with a T-3 flange will offer no improvement over the late stock EGR turbo exhaust manifold.
Can a NA exhaust manifold with a T-3 flange flow more than a stock EGR turbo exhaust manifold with the EGR port blocked? (Better flow being higher exhaust gas velocity and hence quicker spooling of the turbo). Consensus seems to yes and I also agree. You have the manifold and the free time. Build it, test it...then we will know.
Is an early stock non-EGR turbo exhaust manifold better flowing than a later stock EGR turbo exhaust manifold with the EGR port blocked? Yes, definitely better flow with the early stock non-EGR turbo exhaust manifold...especially if you have it ceramic coated.
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-20-2016
Well the idea hasn't been shot down in flaming glory so I'm going to go ahead and do it. I keep hearing welding to cast is rough, and granted this will be the oldest cast I've welded, but I've always had erythromycin good results from tossing the sucker over open flames in the grill, weld what ya gotta weld, and immediately bury in sand so it cools slowly. Only problem, after honing i found the block I was planning to use has a cracked liner, my other block has a small ding in the #1 cylinder wall.. projects on temporary hold until I decide whether i want to resleeve the dented cylinder, hone it out a hair and step up to the next piston size, or proceed as is and cross every digit I have.
Edit: not just good, erythromycin good!! Haha
RE: 617 exhaust manifold bad idea..? - DeliveryValve - 05-20-2016
Resleeve it. Piston cost will kill ya. Sleeves are cheap.
If you don't have a machine shop do it, plenty DIY interweb threads of how to do it at your house.
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RE: 617 exhaust manifold bad idea..? - PanicButton - 05-20-2016
I'd still have to have it decked though eh? I actually already have 3 spare #2 pistons and a cylinder hone though..
I have another thread on this, "cylinder condition" but no one has replied as of yet.
RE: 617 exhaust manifold bad idea..? - DeliveryValve - 05-20-2016
Yep, you still need to deck it and bore it to match the piston. But the DIY part is knocking the sleeve out and installing the new one.
I guess if you can get rid of that dent and the use of piston you have that can match the spec required, you might be good to go. But I'd be worried about messing with the balance weight relating to the other pistons.
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-20-2016
I was thinking I'd use the original connecting rod, weigh the two pistons and possibly match them by losing a little metal underneath, then replace and put the new rings on.
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-20-2016
Anybody familiar with this guy here? W115 exhaust.. is that two entirely separate collector paths I'm seeing?? I could maybe play with this.. a twinscroll setup all of a sudden comes to mind.. worth $30 shipped?
RE: 617 exhaust manifold bad idea..? - CRD4x4 - 05-21-2016
I think that's well worth $30!
Even if it is 2 separate channels I see twins being a problem because it'll be 3 ports to 1 channel and 2 to the other. Idk how a twinscroll would work either because of the imbalance.
If they aren't separate I'd hog out all that dividing material and weld on a flange.
Buy that sucker!
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-21-2016
I clearly have a fundamental misunderstanding of twinscroll turbos lol I've never played with one personally and the way a buddy had described it to me, I actually saw the imbalance as a plus, whoops. but I'm glad you said that because i was torn over just doing that with a traditional turbo anyway. Probably going to try and hog out the 3-1 collection side a little over 13% wider too, if i did my math right, that'll flow about 30% more air compared to the 2-1 side. might not make any impact but if the goal is uniform pressure and resistance... so alright, done and done. Sold. EBay listing said 115 type exhaust manifold, no pictures, but a compatibility chart that matched up right and the guy was selling a ton of other 115 parts.. still crossing my fingers though!!
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-21-2016
It might just make more sense to fill it in, shape it, and tap for new studs also. I'll be sure to post pics.
RE: 617 exhaust manifold bad idea..? - baldur - 05-21-2016
A twin scroll doesn't care too much about balance. Some of those Holsets don't even have a wastegate on both scrolls, only the rear scroll is wastegated.
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-21-2016
I was under the (uninformed) impression that if ya routed a little more exhaust through the "big end" you could end up with a pretty quick spool up
RE: 617 exhaust manifold bad idea..? - DeliveryValve - 05-21-2016
Yep twin scrolls don't care. I'd wastgate the three and have the unbypassed flow with the two.
My thoughts about that w115 manifold is the bends are pretty sharp compared to the w123 manifold. Also that flange points at 7 or 8 o'clock position. You might be able to machine it to close to a 9 o'clock position, drill and tap for studs and possibly bolt on a flange to get a better angle.
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RE: 617 exhaust manifold bad idea..? - PanicButton - 05-21-2016
Oh, see I hadn't paid all that much attention here and it almost looked to me like the w123 and w115 upper end were pretty much the same. I have access to square plastic water vats, would it be worthwhile to play with them both, use a gasket to match to the vat, let the water drain out, and time results/watch for a more uniform flow pattern? Like I said, way more familiar with hydrodynamics over aero, but I know they share many of the same characteristics. And I have mountains of free time lol
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-21-2016
I definitely see the difference after my second look. Good catch. Maybe I'll feel different once they're both in my hands.
RE: 617 exhaust manifold bad idea..? - PanicButton - 05-21-2016
Is that to say it's clocked in towards the engine? Because in my application that'd actually work out just fine, just has to clear the starter, which is about 1/4 the size the one that came with the engine anyway.
RE: 617 exhaust manifold bad idea..? - CRD4x4 - 05-21-2016
(05-21-2016, 01:59 PM)baldur A twin scroll doesn't care too much about balance. Some of those Holsets don't even have a wastegate on both scrolls, only the rear scroll is wastegated.
That's news to me.
My bad.
RE: 617 exhaust manifold bad idea..? - Petar - 05-22-2016
(05-21-2016, 01:59 PM)baldur A twin scroll doesn't care too much about balance. Some of those Holsets don't even have a wastegate on both scrolls, only the rear scroll is wastegated.
Doesn't that cause excessive back pressure for those cylinders that are not wastegated
RE: 617 exhaust manifold bad idea..? - baldur - 05-22-2016
(05-22-2016, 05:14 AM)Petar(05-21-2016, 01:59 PM)baldur A twin scroll doesn't care too much about balance. Some of those Holsets don't even have a wastegate on both scrolls, only the rear scroll is wastegated.
Doesn't that cause excessive back pressure for those cylinders that are not wastegated
Possibly, but they may just have sized the rear scroll slightly bigger to compensate. Then again, old diesels, before all of this emissions control stuff didn't care about air:fuel ratios as long as all the cylinders were getting enough air.