Intake Manifolds and mpg

[MChrist]

I don't think we have a different opinion, just different thresholds of what we consider valuable. It seems you may consider a few hp worthwhile, while us spoiled 3rd gen owners feel that a few hp isn't. However, I still go back to my personal results which showed me that with my stock turbo and Smarty Jr on level 3 and using my built in 0-60 timer (which used speedometer readings from the OBD port). My 0-60 times were exactly the same after I installed then twin turbo setup, even though my boost went up around 10 psi.
By switching up to the Smarty Sr, thus supplying more fuel, my times dropped significantly while boost stayed the same.

 

[HBarlow]

ENafziger and MChrist both sound like you know what you are talking about and both apparently know far more than I do so I'm going to back out of this discussion and leave you with it. It is absolutely true that I am in the minority when it comes to modified Cummins engines. My total experience was with the Bosch RV injectors in a 24 valve.

The reasons I have been so stubborn about this issue is 1) I KNOW that Joe Donnelly is objective, honest, and his test reporting is accurate and 2) I am an old cynic who does not believe self-serving claims by aftermarket parts retailers. Therefore, when I have read on more than one occasion that airbox and exhaust mods to basically stock Cummins engines increase horsepower I hate to see new Cummins owners who do not know better spending their hardearned money on parts that will do nothing because they believe that gas engine modifications will make similar improvements to turbodiesel engines.

 

[cerberusiam]

Increasing intake or exhaust flow WILL NOT increase power until you reach power output levels of approximately 450 hp and even at that power level it would give only minor improvements.



Increasing air flow is gasoline engine technology that does not apply to a diesel. Power production of a diesel is done by increasing fueling and boost.

MChrist, this is the contradictory logic that got everything going. Nobody is arguing that adding fuel will make power. The real point is above, "adding air flow doesn't add power but adding boost does". This is not even debatable but SOMEBODY insisted it was. :-laf



Take a look at the price of diesel and how fast that meter spins when you fill up. As that price inches higher and higher EVER little change starts adding up. Make enough little changes and the impact grows.



Those of us that live the changes, track them, and verify the impact instead of reading the glossy adds and taking them as gospel understand the big picture and the recognize BS when it appears. Ya gotta admit, the above is just what its about.



I tracked the changes on removing the muffler, modifying the air box, gutting the TQ tube on a 3rd gen and it matters. That 25-30 HP in the range I spend 99% of the time that seems so insignificant impacts driveability, mpg, etc.



The 1st gens benefit even more becuase they are more restricted in several more ways. The fact it will knock down 21 mpg at 80 mph running at the same levels as a stock 3rd gen tells the story.



If you want to leave some on the table labeled as significant thats your choice. We can all do as we please and poke fun at HB when he sticks his foot in his mouth. :-laf:-laf

 

[NIsaacs]

Since I don't have any scientific data to back up any major discussion on this thread I am gonna stay kinda low key



However, I will say this; all my trucks are fuel modified but all have stock intakes and exhaust. I always figured that the stock system would feed and exhale the 5. 9 sized engine.



I have been away from big trucks for about 20 years so I can't comment much about todays trucks. However, back in the day of double and almost triple the cubic inch of the 5. 9 we never modified the exhaust or intake system. Yet the big trucks used mostly 3" intake systems on the boost side and 4 and 5 inch exhaust systems. Even with more fuel and different turbos, the air filter, boost piping and exhaust seemed to work fine.



I think the biggest restriction of the 5. 9 when you talk boost or exhaust systems is the engine itself. It will only allow so much volume in and out.



Just food for thought.....



Nick

 

[HBarlow]

MChrist, this is the contradictory logic that got everything going. Nobody is arguing that adding fuel will make power. The real point is above, "adding air flow doesn't add power but adding boost does". This is not even debatable but SOMEBODY insisted it was. :-laf

Take a look at the price of diesel and how fast that meter spins when you fill up. As that price inches higher and higher EVER little change starts adding up. Make enough little changes and the impact grows.

Those of us that live the changes, track them, and verify the impact instead of reading the glossy adds and taking them as gospel understand the big picture and the recognize BS when it appears. Ya gotta admit, the above is just what its about.

I tracked the changes on removing the muffler, modifying the air box, gutting the TQ tube on a 3rd gen and it matters. That 25-30 HP in the range I spend 99% of the time that seems so insignificant impacts driveability, mpg, etc.

The 1st gens benefit even more becuase they are more restricted in several more ways. The fact it will knock down 21 mpg at 80 mph running at the same levels as a stock 3rd gen tells the story.

If you want to leave some on the table labeled as significant thats your choice. We can all do as we please and poke fun at HB when he sticks his foot in his mouth. :-laf:-laf

cerberusiam,

When you spread cake icing over dogcrap it is still basically dogcrap. You're still trying to spin your baloney and play tiny word games to escape admitting you don't know what you're talking about.

I said it then and I'm proud to say it again. Opening the air box or air filter or gimmicks like a boost elbow will not add power to a stock engine but injectors and increased boost will.

The absolute dumbest comment that has been made in this discussion is yours when you claimed a diesel engine must maintain stoichmetric balance like a gasoline engine and is an air pump.

You can't make that one go away. Everyone knows that is dead wrong, well, everyone but you. If you don't understand how wrong that statement is you don't know anything whatsoever about a turbodiesel engine.

I started this argument by trying to explain that opening the intake will not increase air flow because the engine intakes all it needs as is. Your entry into the discussion has been mostly to criticise me personally. You haven't offered anything to prove I am wrong but have concentrated on your dislike and disapproval of me.

Anytime someone spends his efforts in a debate trying to criticise or discredit someone who he disagrees with instead of proving his opponent wrong with facts makes it pretty clear he has nothing to back up his opinion.

 

[Paychk]

Paychk,



Do you think that a Cummins engine in a GenI truck operates any differently than any other turbocharged Cummins engine?

Where did I say that?

By the way. Why do you guys think Cummins installs turbochargers and intercoolers on their engines if all you have to do to improve performance is install a bhaf or a different air box?

Or, are you saying you guys in this forum prefer to remain ignorant?

I speak for myself, ignorance is ... . :-laf

I honestly don't give a hoot what you guys believe or how you spend your money

Then why all the drum beating?

If memory serves correctly I saw a new thread under the "New Posts" heading a few days ago where a TDR member asked if changing the intake system would improve power output and fuel efficiency. Another member told him it would.



I know that to be untrue and inaccurate and hated to see the man who asked an honest question told to spend his money on something that would give him nothing in return besides shiny parts and bragging rights.



You are correct. Joe Donnelly doesn't waste his time here trying to teach some of you anything. He is probably too smart and too busy to waste his time on you. He probably knows that many of you never open the magazine and never read his educated and informed objective test reporting but prefer instead to read and believe the bs printed on shiny paper in one page paid advertisements by companies who sell the fancy junk.

Maybe I should just take a lesson from Joe and go away and forget about you. It doesn't cost me a cent when you guys spend your hard earned money buying junk.

Again speaking for myself, don't go away mad.....

I think some of you are like the guys who buy the products advertised on late night television that will regrow hair on the head of a bald man, make him vigorous, and make the sexy young girls love him.

Hey have we meet? I resemble that remark!



Just in case, you missed the smileys in my first post, it was meant as humor. Maybe throttle back just a tad.



10,000 years from now, when the earth is a ball of ice, what difference does this make?

 

[JLEONARD]

The 3rd gen system is much better at flowing air than the earlier ones, but, thats wrong that you cannot gain until you hit 450 hp.

Yes agreed. 100%.

It's about flow. I worked with Renault engineers in the mid 90s ti help them develop assembled camshafts (a whole 'nother story) and their premise was getting air flow thru the enigne.

Unfortunately I was not inon that part of the development... only camshaft durability testing.



Increased flow also cools the engine and air charge by having less restriction. Increasing low gives a lot of plusses, many of which may be intangible, but they are plusses regardless and thus important.



Happy boosting my fellow diesel heads.

 

[JMcCoy]

I am going to jump in just because it seems the whole TDR membership is here and i am feeling left out.



I am no longer ASE, have no PHD, and hopefully no STD. I agree and disagree with both sides and I'll explain why. I make these statements while extending an olive branch.



First off we'll start with the science theory: It irrelevant whether you are talking about gas or diesel (constant or variable fuel ratio). It makes no difference how the oxygen molecules get in the cylinder, whether it's via extra boost or less restrictive air flow. A diesel will be more efficient with more air to fuel in a given area (cylinder), not to mention the mechanically efficiency of a free flowing engine.



Now for practical: airflow improvements alone are probably the worst dollar for dollar hp/efficiency modification you can do. Someone asked if anyone had any power increase with only a larger turbo. Good luck funding someone stupid enough to waist that kind of money. That said, I replaced my stock exhaust (4” turbo back) and “felt” no difference, just louder. At the time, I only had a #6 plate for modifications. Far from 450 hp. Probably closer to 250 hp. I later installed a ported ATS three piece manifold. I noticeably heard and felt the turbo spool up quicker, pushing me back in the seat sooner. Not harder, just sooner. I couldn't tell you if overall horsepower was increased, but it would make sense if it did. I later installed a Banks twin ram intake. The turbo spooled up sooner yet. A big help since I have 3. 54 gears and 35” tire. It would lug a lot less, proving to me the low end benefits. The biggest difference was in my rear view mirror. When I stomp the accelerator petal (not the gas), there was less smoke, indicating a more compete burn. I was disappointed in that. If I was to guess, I probably gained 15-20 hp with the exhaust, intake, and exhaust manifold. $700 for the intake, $450 for the exhaust manifold, and $450 for the exhaust system. That's around $1,500. 00 dollars. That equals around $75-$100 per hp. Not a good investment. I took that route because I wanted to address the exhaust manifold shrinkage issues, I got the intake used at a good price, and I wanted to make room for future modifications without having to worry about egts.



My opinion: Though I don't totally agree with HB's science theory, I do agree with his practicality. Don't waste your money unless you plan to make big power. Now if you are like me and cannot leave stuff alone, go for it. It would take too long to offset the original cost, but people have spent a lot more money on a lot less. You cannot even make a case for chrome and paint jobs. Ops! I may have just started another argument. Thank you for allowing me to butt in and share my 2nd gen opinion.

 

[JLEONARD]

Now for practical: airflow improvements alone are probably the worst dollar for dollar hp/efficiency modification you can do.

However, many improvements are free or very,very low cost. Do I need to cite some exmples of those?#@$%!

OK,Oo. let's say porting (and polishing) the turbo to exhaust manifold housing, changing to a "free flowing style" air filter (K&N, etc), opening up the air filter housing (applicable to first gens so the newer gen guys may not know what this is), upgrading to a larger turbo when it's time to replace the turbo on a non intercooled 1st gen and changing the compressed air piping diameter, etc.

Therefore when done in conjunction with other mods they make great sense.

Even if you don't have more than 450 horsepower.

I think I have DTD... Diesel Transmittted Disease:-laf

 

[Bob Beauchaine]

Here is my 2 cents worth.



A Diesel is basically an air pump. Air in - mixed with fuel - and air out. The better it flows the better it "works". I purchased my D250 new in January of 1993. I have logged every repair I've done or had done, every PM I've done and drop of fuel for the last 18+ years. I will set out what I've done and the progression of RWHP and Torque with the dyno runs I have been to.



Work done prior to my first run in 2002:

Bosch 185 injectors

K&N air filter

Banks Exhaust

3 Gauge dash mount - Tach, Boost and EGT guages

3 Gauge Pillar mount Oil PSI, Trans/Rear Diff and Coolant.

New 15% IP

60 lb exh springs - BD Exh Brake (mounted at turbo hot side)

Changed down pipe from 2 90 degree bends to 2 45 degree bends ( better Flow)

New NV4500HD trans. Built a rear trans mount to allow straight pipe exhaust.

Mileage to date 18. 47 MPG



9/7/02 247. 1 RWHP 577. 5 TQ. Dynojet Dyno.



BHAF mount with Green HP Air Filter

Banks Technicooler

Rip Rook 4" turbo back Exhaust



6/7/03 299. 0 RWHP 660. 7 Tq Dynojet Dyno



Ran on a different dyno. This is the dyno I like best.

Old Smoky fuel pin



9/14/03 325. 1 RWHP 806 Tq Dynodynamics Dyno



Ran with no changes at PDR in Canada



9/27/03 353. 7 RWHP 895. 0 Tq Dynodynamics Dyno

Mileage 18,52 MPG



PDR HX35 turbo with a 14cm hot side.

ATS 3 piece manifold which was ported.

DD3+ Injectors



5/15/04 369. 8 RWHP 803. 1 Tq DynoJet Dyno



No changes - went to 1st Gen day at PDR in Canada.



9/17/04 377. 9 RWHP 937 Tq

Mileage 18. 50 MPG



Minor pump tweaks.

Note Torque #s are higher with a Dynodynamics dyno ^above^- it can put a load that will give more accurate Torque #s.



5/14/05 378 RWHP 828. 3 Tq Dynojet Dyno

Mileage 18. 49 MPG



Snow W/M Kit Added - 7USG tank.

!st Gen Piston Lift pump

3200 GSK added

Reindexed pump to lower idle.



5/19/07 On #2 394. O RWHP 865. 7 Tq Dynojet Dyno

W/M 440. 9 RWHP 889. 4 Tq

Have since added Custom Home made 4" air intake

TWorline Turbo to IC and IC to intake manifold SS 3" piping.



Mileage as follows

2008 18. 74

2009 19,32

2010 19. 35

2011 19. 62 to date



Bob

 

[MChrist]

It looks like you had aftermarket injectors to begin with. In that case, any additional airflow will help. I believe the question is if additional airflow by itself increases power. I still think the answer is that it "no", or "very little". I also say that it is a poor way to spend $$$ if you don't increase fuel.

Could be wrong... first time for everything... :-laf

 

[CToney]

Wow, if some guys keep stirring the pot I am sure their ladle will break.



Any who, I have some of Tim Worline's cooler tubz on my first Gen and 3rd gen trucks. They both work. They both make a difference on stock trucks. They allow quicker spoolup and increased airflow. Larger diameter pipes offer less friction or resistance to flow. On my first gen I installed the pipe next to the turbo first and the truck sure had more pep. Some may question what works and what doesn't and cost/benefit analysis. Minor benefits are there. On both trucks I have increased the fueling so the benefit becomes greater. The factory has emmisions and costs to consider. Comprimises are made. I believe that I have eliminated some of these comprimises and heck had some fun wrenching in the process.

 

[MChrist]

Once again, it always seems that people notice improvements with airflow AFTER fueling has been increased. I believe the point of this whole thread is to determine if airflow increases improve power on a stock motor. I still say "no or very little".
That has been my experience, but I'm open to hearing from people with real-world results.
It's like when some magazines would have "muffler shootouts", where they would take a carbureted V8 and run the motor on a dyno with different mufflers, and then with no mufflers to see which muffler made the most power. Unfortunately, they rarely took into consideration carb adjustments. They just ran the motor at the same jetting. Well, I can assure you that a car that is running too rich with mufflers will run better without mufflers. Conversely, a car that is dialed in perfectly with mufflers will run too lean without them, so could produce less power without mufflers. I believe that is how some marketing team decided that they can claim that "their mufflers make more power than straight pipes".
Obviously, diesels operate differently, but I hope you see the point.
I've got quite a few big-bore diesels in my fleet, and while they are in excess of 10 liters, excess of 400 hp and excess of 1500lb/ft torque, they come stock with 4" exhaust pipes. Some of my trucks have only 3" intake pipes from the turbo.
So Cummins, Mack, Detroit Diesel, Cat don't know as much as some guy selling 5" exhaust for a 5. 9 200hp/400 tq engine??? Think again.

 

[HBarlow]

Some guys believe that their trucks run better with fuel additives or even with new tires. Perception in the absence of measured results in a controlled test is not very useful.

Scientists understand the placebo effect and use blind or double blind testing to actually measure facts and eliminate perception.

 

[cerberusiam]

Once again, it always seems that people notice improvements with airflow AFTER fueling has been increased.

Spend a little more time reading ALL the posts instead only the ones that follow your pet theory that fuel is the only way to increase power. Multiple posts with experiences and supplemental info indicating exactly the opposite.



Pointedly, if efficiency increases power MUST increase. That would be what is called "proof positive". :-laf It doesn't matter how much, a positive is a positive (that was the discussion point not variables of how much).



AND... AND... you can't turn up the fuel without turning up the air while expecting a successful outcome. Well, I guess you COULD do that like every other yahoo with enough money, the urge to create smoke, and absolutely NO idea what they are doing.

So Cummins, Mack, Detroit Diesel, Cat don't know as much as some guy selling 5" exhaust for a 5. 9 200hp/400 tq engine??? Think again.

Think again for yourself. There is one key thing that none of these venerable companies have any experience doing, installing their diesel engine in to a light duty truck and getting it EPA certified for emissions. Zip. Zero. Zilch. It doesn't matter what any other platform performs like or is configured like. The platform in question is a LD Dodge. THAT makes a difference.



Evidently pointing out the obvious does even begin to get past the glitzy advertisements and opinons of self styled experts.

Then again, basing ones stance on somebody elses opinion and unprovable ideas gives an easy out. Rather than getting ones hands dirty, trusting ones own sense, displaying the cognitive the ability to carry the 5 it is ultimately a lot easier to blame an unknown author when the proof indicates otherwise.



Some people don't want proof either. It doesn't matter what is presented it will never be enough to dissuade those that are so sure of themselves they can't see beyond their limits. These people contribute nothing original to the discussion, have no original ideas, can see no farther than the last magazine they browsed wating in line to get milk.



When its all said and done, an over abundance of proof is provided, the final answer will always be "if its not a santioned study with all the neccessary controls it doesn't count". Yeah, right. :-laf:-laf

 

[MChrist]

Cerb, when I had only my stock turbo my truck was... slow. By installing Smarty Jr, power picked up like crazy. More fuel made my stock turbo boost up to around 30 ish. Then I installed my twin turbos with the exact same Smarty Jr setting, and it ran exactly the same, or at least ran 0-60 times exactly the same. But now it was running around 40 psi. By upgrading to Smarty Sr, (more fuel) now the truck pulled 1. 5 seconds off 0-60 times and boost was around 44.
So, in my case, I maxed out the fuel that Jr could supply. Adding more air didn't do anything measurable. Power went through the roof when I upped fuel through Sr.
I come from an engineering background and fully understand that removing restriction increases airflow. My point, and Harvey's point, is that for diesels, increasing airflow doesn't necessarily make more power if you don't feed it more fuel.
Sure, there may be a hp here or there, but nothing worth spending big $$$ on. Also, you could run any of our trucks on a dyno and experience a 20 hp/40 tq variation between runs.
I appreciate your posts, and have learned much from you, but you're gonna have a hard time getting me to buy what your selling here. . no offense!

BTW, I've owned several motorcycles in the past, have drag raced, road raced, owned multiple muscle cars, and EVERY ONE of them had airflow improvements via modified air boxes, ported heads, roller cams with altered lift, timing, and duration, raised compression, free flowing exhausts, knife-edged crank shafts, etc, etc, etc. . and I realize that airflow/velocity is crucial... in gasoline engines. I just haven't heard of any of it helping an otherwise stock turbo diesel engine.
Maybe when you get past a certain horsepower or RPM level, but not an otherwise stock turbo diesel.

 

[JLEONARD]

Harvey's point, is that for diesels, increasing airflow doesn't necessarily make more power if you don't feed it more fuel

No that is not what I read. He said airflow only applies to gas engines and not at all to diesels.

Increasing air flow is gasoline engine technology that does not apply to a diesel

And, if the extra air allows the existing fuel level to be burned, or more completely burned, then there is an improvement.

Sublte? Perhaps. Real? Yes. Worth your time and $? Maybe not.

Might be worth it to someone else. It was to me.



Addressing the original question as to whether improvements will increase mileage? I would say not enough to be measurable.

 

[cerberusiam]

MChrist, I understand what your saying. I don't disagree with anything you say about adding fuel, increasing track times, etc. Thats not really the point, nor am I selling you anything. You free to agree or disagree.



I am positive that when you added the twins, Smarty Sr, etc, you also addressed air in and air out. Not that you couldn't run all those mods thru a stock muffler, CAT, and suck the air thru the stock filter and air box but WHY? All the mods and fuel in the world is not going to be anyrhwere near effective if there is not enough air to support it.



Did you do any testing on the stock components to see where the limits were? I did some testing, not scientific with placebos and control groups and all that, but testing the same with muffler on\off, air box & TQ tube stock\modded, air filter in\out. Naturally as the fuel was added the benefits became more and more apparent, but, I did see slight gains at stock power.



Probably the most telling indication was the filter minder. When you can pull the filter minder over half way down on stock fueling just by driving it hard, there is a restriction. There is no way around the deduction that more air is going to add power even stock.



As to the cost benefit ratio, if one is going to buy a $350 CAI plus a $700 exhaust system plus a $250 intake and expect to see some high value gains, you are correct in stating the cost ratio will be high. Is it worth it? Well, that depends on the individuals perception, what he intends to do, and where he wants to take the truck in power levels. There are cheaper ways than above to achieve the same results.



Bottom line is there are benefits, some not so easily quantifiable, some purely based on math or expected results. To say there is NO benefits until 450 HP or more exhibits a total misunderstanding of how air flow functions in a diesel engine, how diesel combustion works, etc.



Pointing out the cost benefit ratio does not relate well until one goes past 450 HP is correct, I totally agree. Sharing conclusions and information that possibly may be overlooked is what these forums are all about.





To be a snot because people disagree with a pet theory is, well, we all know the 4 W's of that.

 

[MChrist]

Who's being a snot? Where did that even come from???

 

[cerberusiam]

Who's being a snot? Where did that even come from???

For the record, not you.



Just an observation on the communication techniques employed in some posts regarding dissenting opinions and the reasons behind those opinions.