Can't remember now. The other factor is the pulse which is very very important. And there can't be any expansion at all in the line. Your not even supposed to rebend a line as it dislodges the internal lining.
1HD-T Intake Manifold Modifications
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Can't remember now. The other factor is the pulse which is very very important. And there can't be any expansion at all in the line. Your not even supposed to rebend a line as it dislodges the internal lining.
So I been doing some googling as of late and found this neat article pertaining specifically to diesel intake manifolds. Although the abstract does not describe the diameter of the runners, or if they are tapered, it does say there are some good gains to be had increasing the volume of the plenum, or at least having a plenum in my case, for more even cylinder filling. It did have a significant impact on BCFC as well which is really neat. I tried to purchase the article, but it didnt like my card.
http://asmedl.org/getabs/servlet/Ge...4298000171000001&idtype=cvips&gifs=yes&ref=no
http://asmedl.org/getabs/servlet/Ge...4298000171000001&idtype=cvips&gifs=yes&ref=no
Cool. There has always been a benefit to the intake manifold mods. The only difference is what size volume you will need for your application. Getting all the variable correct.
3x swept volume. Hmmm
Roughly a 150mm pipe of 0.7m long and that's only 10 litres, I need 12. That's huge.
Well as far as I have understood, larger plenum usuall denotes better incylinder filling, but at the cost of lagg and decreased throttle response. Now throttle response would only pertain to a throttled diesel such as a 3B (me).
I am interested in using a duel plenum design to aid in cylinder filling, but keep the volume to a doable size. Something like this. Although I think this fellow raised his trumpets a little far off the floor:
Just working out runner lengths on a basic manifold calculator and it says it should be 42 inchs long. So ive pretty much givin up on resonance tuning for diesels. After much manifold image searches, it would seem that no one else tunes lengths either. Its just way too long.
I am interested in using a duel plenum design to aid in cylinder filling, but keep the volume to a doable size. Something like this. Although I think this fellow raised his trumpets a little far off the floor:
Just working out runner lengths on a basic manifold calculator and it says it should be 42 inchs long. So ive pretty much givin up on resonance tuning for diesels. After much manifold image searches, it would seem that no one else tunes lengths either. Its just way too long.
So the isuze engine gained 10% with just a mod to its manifold? That is crazy. That is crazy good, cus my stock intake has about as much thought in its design as you would use shelling a peanut. Lots to be gained.
I think the bigger plenum allowed better VE at higher rpm. Peak torque at 2000rpm wasn't anything special (67Nm per litre), but the 3,500rpm peak power was almost 500rpm higher than the 3.9. Shorter stroke too.
http://www.isuzu.co.nz/media/1914/NKR300S CVO166 Sep 98.pdf
In other news. Parcel arrived today and it works on our network.
I think you read it wrong. A 3.6 with intake mod put 10% more than the 3.9 without the mod.
Ahh yes I did read it wrong, but that makes it all the better. And good to hear your package it working Doug. Even though the runner would be short, I wonder if you could still do some tapering on it for increased velocity as well as a bell mouth. I was reading an article of a fella comparing straight intakes with flared bell mouths and full radized bell mouths and the simple flared ones flowed 25% more than straight pipe. The full radized ones did about 2% more than the flaired ones. So not a huge amount. The pic I put up a few posts ago is a good example of a simple flared bell mouth. I dont know how acurate this is, but perhaps an engineer could verify these measurments?
I did just find this neat paper trialing different taperd intake runners, but havent read through the entire thing yet.
http://etd.ohiolink.edu/send-pdf.cgi/Howard Todd Michael.pdf?osu1184186829
you just have to click display full text to see the whole article
http://etd.ohiolink.edu/send-pdf.cgi/Howard Todd Michael.pdf?osu1184186829
you just have to click display full text to see the whole article
When I was younger and into drag racing. A friend of my father was ex aircraft engineer. Had a flow bench with a fluid level. The trumpet pipe vs straight made an extra 100hp for no other mods. But I think your still missing a few things. You can improve the intake efficiency by this plenum mod. But it can still only flow as much as the head will let it (next restriction in the line). Boost is a factor of restriction. Having a large volume of chilled air charge right there in the plenum. Means you don't really need to bell the intake. It's right there (shortest distance to engine as possible) = least resistance. So it's really a case of instead of the trumpet intake, but the intake mod helps it flow better much higher in boost/volume. Low boost-large plenum = lag. High boost with Inefficient intercooler=lag. You either reduce the plenum size, or chill the air as much as possible as low in the rpm as possible. The more air mass, and added fuel. The more gasses-turbo spool. This will allow you to have minimum lag and no compromise for high end flow.
to bad there is not enough room to extend the manifold past the last runner on the 1hdt,now that would be the ticket .
OK so Biggie im not sure im getting everything your saying, but I know for sure that the shortest distance does not equal better cylinder filling. Its not about resistance, its about intake charge speed and density. And low boost or high boost makes no difference as its volume your modifying. resonance tuning would definitely be wacky with boost and high temps, but I think that is not feasible for the rpms these engines run. I was thinking it would be good to get collection of some proven techniques and formulas and see how they could be worked into a manifold. I dont agree that the engine will only flow as much as the head will let it as all of these trouble areas are cumulative. As they get dealt with and improved I dont see how it wouldn't benefit cylinder filling.
I have already done some intake valve work and mild porting around the valves for breath ability. Low lift valves tend to choke up mostly right at the valve area and with the valve cuts themselves and not so much in the runners or bowls. I did the exhaust quite a bit for transitions and obvious turbulent areas. The 3B head offers some seriously dramatic transitions which cant be fixed easily, especially on the exhaust side. I guess welding could work, but building up the exhaust runner floor with a stainless rod is beyond me.
I have already done some intake valve work and mild porting around the valves for breath ability. Low lift valves tend to choke up mostly right at the valve area and with the valve cuts themselves and not so much in the runners or bowls. I did the exhaust quite a bit for transitions and obvious turbulent areas. The 3B head offers some seriously dramatic transitions which cant be fixed easily, especially on the exhaust side. I guess welding could work, but building up the exhaust runner floor with a stainless rod is beyond me.
if you are talking about your charged air ,(intake),if you log taper your plenium you will choke your last runner i have personally found and apparantly if you extend it past a bit this solves this chokeing problem and puts a little more pressure on the first runner. i abanded the tappered plenium style after i was schooled on this and was asked if i was building penstock or a plenium. cant say either way if i was taught wrong.tapperred sure does look smart though,i can see that if your trying to do number matching per cylinder forget it,so i did .besides the manifold part of the mods was a pretty basic goal, make it about a gallon and not tapperred. i am sure gbenik can touch on this therory .
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Actually I wasn't referring to tapering the manifold itself, but rather each intake runner. I don't see a benefit to tapering the manifold and would only do it if your engine compartment dictates it. What you have said about starving the last runner is consistent with what I have read as well, although tapering it is suppose to be a technique to keep the incoming air speed up for the last runner. I personally don't like those designs though, as in the side entry. I prefer the top down type.
Yeah, your not getting it. At high flow (top end) the flow from snorkle to intake manifold is the restriction. Having charged air right there helps this ALOT. And having to pressurise a large volume area before boost is achieved = lag.
Perhaps that is the greatest restriction. However, I dont think were trying to figure out that in particular, but rather how to build a good intake manifold. Yes volume = lag, but the volume we are describing in building a manifold wouldnt be greater than the piping used in a front mount intercooler and no one seems to mind that if the bennifit is there.
