86' non-turbo intake???

[adill]

Hey guys, I am new to the forum and a new diesel owner. Just bought a 1986 6.9 IDI with 170k original miles. I have read that adding an intake and exhaust will help keep EGTs lower. I am going to have a muffler shop bend the pipe for me for the exhaust, but I'm wondering if anyone has built their own intake? If so, what material did you use and what size was it?
Thanks in advance!

 

[79jasper]

For non-turbo, not as many options.
But search around here, I believe some have built one.

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[IDIoit]

INTAKE: kind of a mute point with a 6.9 N/A
you will not benefit anything for drawing more air with a modified intake.
the intake ports are huge, and unlike a gasser, they do not atomize a fuel ratio, they just flow air through an air cleaner.
if you really really wanted to spend the time and money, theroetically you can make a intake out of steel flanges and tubes.
sticking straight up with air filters on them, but that would be a part of what i call
"ALL SHOW AND NO GO"

YOU WILL NOT SEE ANY HIGH hp NUMBERS OUT OF A NATURALLY ASPIRATED 6.9
just not really worth it.
the engine would prolly run without an intake.

HEADERS: going to your exhaust shop and "having them bend somthing up", will look like ****.
what are your welding skills?
ive built dozens of headers, now a days i wont even think about building headers unless its 301 stainless .065 wall. TIG welded
nothing but mandrel bends for me.
it takes time to build headers. they are not for the faint hearted.
again, without a turbo, youre doing this for all show, and no go.
no disrespect, but thats kinda lame...
do what you wish, but if i were you id spend the time and effort on a turbo

by the way, welcome to the forum.
you should really check this site out, its amazing!
http://www.oilburners.net/forums/forumdisplay.php?146-Introduction

 

[adill]

Thanks for the info! not really looking to do headers right now, just bigger exhaust. Would that do my EGTs any good?

 

[stealth13777]

I wouldn't think you'd have to worry about egt's n/a. But there are guys here running n/a who can answer your question; I've been turbo'd whole time I've had my truck sorry


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[79jasper]

Yeah IDIoit, I didn't see him mention headers. Lol just exhaust.
It could help if you go bigger.
Get a unrestricted muffler.

N/A vs Turbo really have nothing to do with each other far as EGT's go.
In most cases a turbo engine will run cooler. Very easy to melt down a N/A.

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[adill]

Yeah IDIoit, I didn't see him mention headers. Lol just exhaust.
It could help if you go bigger.
Get a unrestricted muffler.

N/A vs Turbo really have nothing to do with each other far as EGT's go.
In most cases a turbo engine will run cooler. Very easy to melt down a N/A.

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79jasper, so I should put a bigger exhaust/nonrestrictive muffler to help with flow? If the N/A are east to meltdown, should I also install a Pyro gauge?
Thanks

 

[79jasper]

Yes, you should. Especially if there's any chance the fuel setting has been/will be messed with.
If going single exhaust, 4 inch would be more than enough. Plus be big enough if you decided to turbo it later.
But 3 or 3.5 would be fine also.

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[stealth13777]

Yeah IDIoit, I didn't see him mention headers. Lol just exhaust.
It could help if you go bigger.
Get a unrestricted muffler.

N/A vs Turbo really have nothing to do with each other far as EGT's go.
In most cases a turbo engine will run cooler. Very easy to melt down a N/A.

Sent from my SM-T537R4 using Tapatalk

Learn something new every day. I was dead wrong on that one. Some guys on here have cowl intakes installed. Let me see if I can find one of the threads. Idk if that would help you, but it's an idea.

Edit: use the method of typing into google 'siteil burners.net _______' (I searched for cowl intake). This is one thread that came up which might interest you. Most of the guys using it that I found in 2min of searching have turbos, but it seems it may work n/a too.
http://www.oilburners.net/forums/showthread.php?48772-cowl-intake-vs-cold-air-intake

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[LCAM-01XA]

Headers are not needed on a N/A truck (tho they sure would help some), but larger exhaust past the manifolds is. The problem is the factory pipe is not only small in size but also very poorly designed in the merge area between the left and right sides, if that section alone gets improved and opened up to say 3" and then followed by again 3" towards the back this will be of great help.

Intake is pretty good on these trucks, it's 4" and in your case it pulls from behind the grille which is more or less factory ram-air setup. What you need to check is your air box - some have a restrictor plate welded to the bottom that covers a significant portion of the otherwise nice and wide lower opening, if you have that you can either try removing said plate somehow or you can grab an air box out of a 7.3 truck (direct fit for your 6.9 sans the restrictor plate). Alternatively if there is no restrictor plate on the bottom opening then your upper lid has what's known as a "soup bowl" welded to its underside - that can be removed as well and in theory it should allow more air to come in, how much that actually helps seems to be open for debate.

 

[IDIoit]

guess i went off the deep end on this one lol

 

[icanfixall]

guess i went off the deep end on this one lol

At least it wasn't in shallow water...... To the original poster. Welcome to the forum and new to you truck. You appear concerned about exhaust temps. Why? Do you know what they are now? Sadly the factory exhaust is very small for these engines. Many times the mufflers plug up with soot and when you remove them they weigh a ton. If you can explain more about what the muffler shop plans doing we can comment on what we know works.

 

[sjwelds]

On mine before I turbo'd it I had a Hypermax cowl induction intake and an Afe dryflow air filter in the factory air box with "soup bowl" removed. And as others have said, down under the truck where the driver's side pipe connects to the passenger side is a very restrictive point. I cobbled together a custom deal where I ran each pipe into a 3-1/2" single pipe and then into a free-flowing 3-1/2" muffler.

Yes it does make a fair difference in power. But...as others have said......a turbo will do way more than all these things put together. Just sayin

 

[PwrSmoke]

Welcome to this motley crew!

Do you have a pyrometer? If not that's job one. You have to verify the stock situation and observe the improvements otherwise it's an exercise in automotive ************. ( : < )

Exhaust? the two hot spots are the y-pipe and the muffler. It would be fun to run back pressure tests and see. One thing... I did an exhaust story some years back where we flow benched mandrel bent vs standard crimp bent tubing. Same diameter, same length of pipe, etc.... 30 percent increase in flow for the mandrel. Eye opening! Makes it worth the money for mandrel if you can get it.

In theory, a single 2 1/2 system has the flow for an NA 6.9L, but maybe not if you count a bunch of crappy bends and a crappy Y in the front pipes. With a normality bent system you want it a bit larger to account for the crimp bends, so a 3-inch is about right. A mandrel bent 3-inch with a good free-flow, straight thru muffler is more than enough for even a turbo diesel to about 14 psi boost.

Remember that the exhaust is good until it isn't. Pipe size alone (no tuning, just bigger pipes) on gains you in the upper rpms. In many trucks where I have tested backpressure, diesel and gassers alike, you got zero or near zero until a certain point (dictated by RPM and load... load makes the exhaust hotter and increases the volume of the gasses). If that point is at 2800 rpm, you don't gain much putting around town at 1500 rpm. A tuned system might gain you in the mid range too.. by tuned I mean headers and/or equal-length downpipes with a good Y.

I haven't messed with the exhaust in my turbo IDI much (it has a 4-inch replacing the original Banks and it was worth a zero percent increase in power) but I have checked backpressure. The original Banks system was under 3 psi at max boost, 3000 rpm, which is excellent. The 4-inch system is the same, telling me the restriction is upstream in the remaining parts of the 3-inch Banks (basically the downpipe about 3 feet long from the turbo- that tap is in the down pipe).

In working a story on my F-150 gasser, we tested a stock system vs the stock system and a free flow muffler vs a cat back 3-inch system. We checked both backpressure and on the dyno. The backpressure was higher with the stock muffler but when we installed a straight they muffler on the stock pipes, the backpressure at 5200 rpm dropped about 45% and the truck gained about 75 percent of the power it did with the full 3-inch mandril system. Pretty interesting I thought. The muffler was about $60, the full system was about $300 (the muffler was the same brand and type as on the full system, just with 2.5" in and outlets) but when you divided the dollar per HP, the muffler was the better buy.

 

[Kevin 007]

I once installed a vaccum gauge in the factory air filter box of a N/A and there was no vaccum produced with the engine running with the stock air inlet. So, the engine is getting all the air it needs and isn't scrounging for more. I like the idea of a "ram air" setup on any engine and it certainly would not hurt your case but you probably won't notice a change in performance. I have always wanted to take the inlet off my parts rig and add a second factory air inlet duct to the other side of my air filter box and run it to behind the grill on the opposite side of the rad as the stock inlet. I wouldn't expect to get any noticable difference in power, egt's or mpg's but it would still be cool.