N/A Diesel Exhaust Theory

[carsonlhammond]

I’m also thinking of going the blower route on my engine, a little bit to keep the N/A sound but mostly low end torque. I want to make a real low rpm workhorse. I’ve been thinking of using the m122 off of a mustang as they can be had used in decent condition for 5-700 bucks on eBay. One fellow tried it in his bronco on YouTube with an m90 and he had the thing spinning so fast just to push enough air that it was extremely obnoxious, so he gave up... So with a larger displacement charger spinning at a reasonable speed I think it could be done without beating the intake charge and whining your ears off. Again I don’t care what it makes above 2800-3200. I want something that just makes torque, lots and lots of low end torque.

 

[Enginerd]

Exactly the same reason I would go for a supercharger - the low end and instant torque. The most efficient design I've come across so far with the little research I've done seems to be the twin screw. It apparently runs cool, has a 100,000 mile service life, is well packaged, produces great instant low end torque, and doesn't draw too hard off the engine. It seems to be a good possibility and wouldn't require too much boost to see good results I would think. But that's a dream for further down the road for me...

 

[31 AA]

If you look at my avatar pic. It’s a 1931 AA (2ton with duals) 3900+/- lbs (depending on the holiday).top speed down hill 45/50mph 40hp@2800rpm redline 3000rpm. Now it will Cruise at 65 mph @ 2600 all day long.it takes Min.55 hp to run the O.D. UNIT. So like the idi you are hunting HP in a limited rpm range. In my case every little thing I could muster.7:1 compression (stock 4:2 to 1) balanced to a 1/2 gram rotating Assembly,larger intake valves, aluminum time in gear,BIGGER CAM,Weber 32/36 downdraft carb and cast iron headers, electronic ignition and a couple of evenings tuning. I look at the IDI the same way and approach. The little things that people said wouldn’t mean much mattered.and I get it build and improve the old engine then transfer parts and ideas to new fresh engine.i’m in the process of doing the same thing to a 92 idi 4x4 E4OD XLT. BUILD the truck to your needs headers,intake,fuel CAMSHAFT,valves,springs ect.ect. Hope this helped

 

[31 AA]

Almost for got I have a 871 blower from a Detroit. Just saying if you go that route

 

[carsonlhammond]

I already have a typ4 low rpm cam and arp headstuds. I’m getting quite a bit of blow by but I still have 400+psi in ever cylinder with the highest being 410 low being 402. I’m not sure how I would go about building an intake as I can’t tig weld but I heard you can mig weld aluminum. Sorry I know this is a little off topic for the thread but I feel like it ties into it in a way because after you get all said and done with the blower you might as well get the exhaust as efficient as possible. Sure the blower helps clear out the cylinder if you have lots of overlap (not sure how much mine has, Russ @typ4 maybe you could chime in on how you think your cam would do with 10psi at 1500 rpm. Just guesssing on those numbers) but you’re working it harder to push through an inefficient exhaust right?

 

[carsonlhammond]

And you’re also probably better off with true duals at that point to eliminate reversion as someone else stated. I think??‍

 

[Enginerd]

I’m not sure how I would go about building an intake as I can’t tig weld but I heard you can mig weld aluminum. Sorry I know this is a little off topic for the thread but I feel like it ties into it in a way because after you get all said and done with the blower you might as well get the exhaust as efficient as possible. Sure the blower helps clear out the cylinder if you have lots of overlap (not sure how much mine has, Russ @typ4 maybe you could chime in on how you think your cam would do with 10psi at 1500 rpm. Just guesssing on those numbers) but you’re working it harder to push through an inefficient exhaust right?

Yes you can weld aluminum, you just will want to have the little standalone spool gun if you want the easiest setup, and you have to use pure argon if I remember correctly. I've still been pushing the aluminum wire through my hose just like steel wire because I'm cheap, but you have to have the hose routed basically straight between the machine and the gun. But yes, I have done it successfully many times, and this is how I plan to build my intake when I get done with the exhaust.
A few comments on the reversion statement. I was the one who had brought it up because I found the comment in another forum but no justification, and I just don't buy it. I would think an x, h, or a well placed y would only help. I would like to try some anti-reversion chambers in one of my headers I do to see if it helps any, but my understanding is you don't get too much reversion on a low duration cam and I doubt any cam made on these diesels have anywhere near enough overlap to be considered large cams...
I'm interested to hear the comments on making the blower work harder. I think 10 lbs of boost is 10 lbs of boost, regardless of the actual flow. But I have no personal experience with boost. But that's some of the reason I was saying I want a good exhaust before supercharging.

 

[carsonlhammond]

If you look at the banks power videos lately you’ll see very clearly how any old boost is not the same as “denser” boost. If it’s cooler it’s denser and much more capable of power. So if the blower can mover more air more efficiently (cooler) at the same boost level it will make more power. Same goes for turbos. But I’m currently putting a different turbo on than the h1c I had started getting put on. I just don’t like the compressor efficiency and size. I want something that spools low, which it would, but the compressor is just too small being made for a 5.9.

 

[IDIBRONCO]

So assuming a perfectly uniform timing of the exhaust pulses merging together, scavenging could have a major effect on the volumetric efficiency. These are pretty low lift, low duration cams so that poses a challenge, but a well played NA exhaust and intake could really do good in filling those cylinders with fresh air and exhausting the residual burnt gasses.

Here's a "damned if you do, damned if you don't" to throw at you on exhaust efficiency. The exhaust ports, right where they start to exit the head are really choked down (in my very unexpert opinion of head flow) and can stand some opening up. Sure. You can force a Huge amount of air through them with a turbo or supercharger, but they still don't FLOW as well as they could. I ported my heads and I feel that it made a decent difference. Is it anything to put in the IDI performance Hall of Fame? No, but a gain is still a gain. Of course for you to do this, you need to remove the heads. At that point, how far are you going to go? Rering? Full rebuild with new pistons and the whole nine yards? That's the downside. No, you wouldn't have to go farther than pulling the heads, but where do you stop?

 

[03wr250f]

couple things you are talking about $200 into exhaust versus $5-700 in a used turbo kit I know which one I would go.


but i will give ya some of the stuff I found while trying to optimize my truck when it was still n/a. I ran a turbo cal ip, and stage 1 injectors. Properly matched injectors made a 10 mph difference going up a 6% grade (4th of july pass in idaho) at the same 1150* egt. I swapped injectors then the next weekend mad the same trip and pulled the pass 10mph faster. I was blown away.
I also had a ray bell air cleaner which has a bigger soup bowl then factory and a butterfly down where it goes into the intake. that dropped egts 50* cruising down the road.
I also added a 4' exhaust with muffler from the wye pipe back and that dropped me 150* egt cruising down the highway. I know if I would have made my own wye pipe instead of the factory I would have dropped egts slightly increased power slightly and reduced smoke slightly. It wasnt worth it imo tho.
the truck ran great, had awesome power for a n/a and got good mpg. 16 ish still nothing like a turbo. I had to hit the bottom of the continental divide at 85 to crest the top at 65.
the intake from the factory is basically as good as it gets. they made it a long runner intake that works very well because they were competing a n/a diesel agianst turbod trucks of the time. Also most anyone who actually flows idi heads and then ports them finds there is little to be gained and acutally you usuall do more harm

 

[carsonlhammond]

Wes has stated before that an idi actually flows extremely well in the head department compared to Powerstrokes.

 

[nelstomlinson]

I’ve got a banks powerpack intake cover ...

I have one of those! Is it worth the minor trouble to swap it on?

 

[Thewespaul]

I have one of those! Is it worth the minor trouble to swap it on?

Why don’t you tell us

More filter surface area-less restriction, can’t see why it wouldn’t help.

 

[BrianX128]

My crew cab has the banks power pack and a custom exhaust with a bigger/better y pipe, its N/A and heavy and it's got more power and gets better mileage than my dads factory turbo single cab [though it's an e4od and I'm a zf5] but it should be the other way or worst case even.

It's not always black and white, I guess is all I'm saying.

 

[nelstomlinson]

Why don’t you tell us

More filter surface area-less restriction, can’t see why it wouldn’t help.

Huh, I thought it used the stock filter. I'll have to double check that.