I Finally Completed My Intercooler Installation

[TurboDiverArt]

Hi All,

I finally got around to installing my intercooler. BIG thanks to Kent for all his help in first coming up with this idea and then sending about an hour on the phone with me regarding the installation. I took a slightly different approach. I decided to remove the bottleneck upper intake from the equation vs. flipping it 180-degrees as Kent did. I had an engineer buddy of mine fabricate a new upper intake. In looking at the lower intake I think the original design from Detroit had the air intake charge coming in from the top. If you remove your upper intake you will notice a large bump exactly in the middle of the plenum that must have been used to take an air charge from the top and evenly distribute it. Naturally GM screwed it all up by putting that 90-degree bend side discharge upper on. I decided to have a 3/8

[signgrafix]

You know I purchased a used intake for my 6.5 to look at it for ways to modify it. I am like you, I think the top half is a poor design but then again, I do not have a engineering degree. Keep us updated on how it does. That is a good looking piece on the intake by the way.

[ronniejoe]

The "large bump" is a cast boss that is there for EGR equipped vehicles. The EGR valve mounts to the top of the upper intake and connects into the boss internally. GM used to make an upper without the boss for the F engines, but the cost cutters forced them to use a one for all approach. Many of us have removed the boss completely from the inside of the upper intake. Once this is done, it is really a pretty good piece for transitioning from 2" round to the shape needed for the lower intake. It does a good job of slowing the air velocity before dumping into the manifold plenum. The custom piece in the photo will have very severe exit loss as the air moves from the "cobra head" into the plenum since there is no transition area.

Your set-up will be better than what you had before because of the intercooler. However, a modified factory upper turned around would have been a better solution. Just my two cents.

Good work!

[gmctd]

FYI - check Peninsular parts, with the pic of a late n\a 6.5 - that pent-roof shaped upper plenum seems ideal for c-a\c installation.

Can be rotated for r\s or l\s entry

[TurboDiverArt]

FYI - check Peninsular parts, with the pic of a late n\a 6.5 - that pent-roof shaped upper plenum seems ideal for c-a\c installation.

Can be rotated for r\s or l\s entry
Is it on their website? I don't remember seeing anyone that was making one. Do you happen to have a link?

Art.

[gmctd]

It's on the Peninsular site, under 6.5 parts - they listed all the new pull-off parts not needed in the marine conversions.

http://www.peninsularengine.com/hummer.htm#17 - intake adaptor - it's oem factory part.

[TurboDiverArt]

The "large bump" is a cast boss that is there for EGR equipped vehicles. The EGR valve mounts to the top of the upper intake and connects into the boss internally. GM used to make an upper without the boss for the F engines, but the cost cutters forced them to use a one for all approach. Many of us have removed the boss completely from the inside of the upper intake. Once this is done, it is really a pretty good piece for transitioning from 2" round to the shape needed for the lower intake. It does a good job of slowing the air velocity before dumping into the manifold plenum. The custom piece in the photo will have very severe exit loss as the air moves from the "cobra head" into the plenum since there is no transition area.

Your set-up will be better than what you had before because of the intercooler. However, a modified factory upper turned around would have been a better solution. Just my two cents.

Good work!
Possibly but I'm not 100% sure I agree. The "bump" I'm referring to is in the lower intake manifold, not the upper. My main concern with the stock upper and using 3" intercooler piping is that the necking down from the 3" to the 2" then back into the "fan" laterally (left to right) is that you are increasing the velocity as you transition from 3" to 2". The stock upper intake I feel fails in the same way as other stock GM designs. I think what it's doing is causing the rear cylinders to be leaner than the front. The stock Grand National turbo charger upper intake fails in much the same manner. In both designs the boost velocity is forced against the back wall of the manifold causing the rears to be lean. On the GN this causes frequent blown head gaskets in the number 5 and 6 cylinder (rear ones). Many people weld in or shape a scroll down to better direct the boost down into the manifold helping to equalize the pressure across the intake runners. When I looked at the stock 6.5 upper I thought the same thing although not to the same degree as the GN

[TurboDiverArt]

It's on the Peninsular site, under 6.5 parts - they listed all the new pull-off parts not needed in the marine conversions.

http://www.peninsularengine.com/hummer.htm#17 - intake adaptor - it's oem factory part.
Not finding it. I'll have to look harder on the site when I'm home. I don't see any parts numbered and none of the ones on the 6.5 Parts page list anything about intake. I must be going blind in my old age... :)

[TurboDiverArt]

Not finding it. I'll have to look harder on the site when I'm home. I don't see any parts numbered and none of the ones on the 6.5 Parts page list anything about intake. I must be going blind in my old age... :)
Forget it, I found it. Eyes must definitely be going. I was not on this particular site. The one I was on had a blue screen and only listed text, no pictures. I agree, that intake looks much nicer than the stock truck one.

Thanks!

[gmctd]

Remember, Art - gassers inject fuel into the incoming air stream on the intake stroke - Diesels inject fuel at the top of the compression stroke, cylinder is already full of air.

[TurboDiverArt]

Remember, Art - gassers inject fuel into the incoming air stream on the intake stroke - Diesels inject fuel at the top of the compression stroke, cylinder is already full of air.
Yes, true. My thought was that there would be a bias towards the back cylinders. If the adage that "boost always finds a way" is indeed true then the intake path, as long as it's not restrictive, has no bearing on cylinder pressure imbalance. I believe in a gas situation, the problem is that more air is being forced to the rear cylinders. Same amount of fuel is injected per cylinder (sequential fuel injection), more boost to rear with same amount of fuel equals a leaner condition as compared to the front cylinders. Taking fuel out of the equation, the rear cylinders I think are still seeing a high-pressure differential than the fronts. I do think that at the boost levels most people run with these engines, it's not that big of a deal. With the Grand Nationals you typically don't see a big problem with the rear cylinders running lean until you get to about 25 PSI. I don't think too many people are running the 6.5 at much more than that.

Art.


Art.

[gmctd]

The GN intake is front-fed, and since air does not easily take to directional changes in course, the hi-velocity compressor output would hit the rear of the plenum first, thence into the closest cylinder ports, 3 and 6.

Not that the other cylinders are starving, but the last two are getting some unwanted help from that velocity, as you surmised, and would worsen with increasing crank rpm.

Even tho the entire plenum is at Boost pressure, it's the velocity prior to the directional change that is causing the leaning problem.

BTW, directional change is one method of converting air velocity to air pressure.

And while the 6.5 is lower rpm, by half, and the intake is center-fed, #8 cylinder does show more scuffing, but mainly from increased ingestion of dust particles, vs the other cylinders.

JimB spoke of this effect a good while back, possibly resulting from the 90deg plenum curvature from the compressor, with a bank-shot directly into port #8.

But, since Diesels run best if 'lean', that has much less effect as with a gasser.

The leaner a Diesel runs, the slower the crank speed - that's all...............

[TurboDiverArt]

The GN intake is front-fed, and since air does not easily take to directional changes in course, the hi-velocity compressor output would hit the rear of the plenum first, thence into the closest cylinder ports, 3 and 6.

Not that the other cylinders are starving, but the last two are getting some unwanted help from that velocity, as you surmised, and would worsen with increasing crank rpm.

Even tho the entire plenum is at Boost pressure, it's the velocity prior to the directional change that is causing the leaning problem.

BTW, directional change is one method of converting air velocity to air pressure.

And while the 6.5 is lower rpm, by half, and the intake is center-fed, #8 cylinder does show more scuffing, but mainly from increased ingestion of dust particles, vs the other cylinders.

JimB spoke of this effect a good while back, possibly resulting from the 90deg plenum curvature from the compressor, with a bank-shot directly into port #8.

But, since Diesels run best if 'lean', that has much less effect as with a gasser.

The leaner a Diesel runs, the slower the crank speed - that's all...............
I may have gotten my calendar numbers incorrect. I assumed the 6.5TD was the same number setup as gassers with odds on the driver

[gmctd]

I haven't looked at my GN engine in a very long time, but I was assuming even on passenger-side, odd on driver-side, with #8 being rear-most passenger-side on the 6.5.

At any rate, passenger-side proximity to turbo heat seems to be more problematical.

Do you see that in your cars?

[TurboDiverArt]

I haven't looked at my GN engine in a very long time, but I was assuming even on passenger-side, odd on driver-side, with #8 being rear-most passenger-side on the 6.5.

At any rate, passenger-side proximity to turbo heat seems to be more problematical.

Do you see that in your cars?
No, not really. I would say I have blown the rear two pretty evenly.

Do you still have your GN? What year? Are you on any of the boards? I'm heading to Norwalk Ohio tomorrow night for a Turbo Street Outlaw (TSO) race.

Art.

[DA BIG ONE]

Art, You did a great job and for far less $$$ than my smaller CA/C from B&D and yours looks about twice the size.

[gmctd]

Yep, I see now - I totally missed your response to rj, so I was just repeating you.

Nice installation, btw.

I installed a late '86 GN engine, with the GNX ECM and associated electronics upgrades, in a Mitsubishi Starion, but insurance hassles terminated the project, then MHI put the DOHC 3.4 engine in the Trooper, so the GN 3.8ohv project became pointless.

Then proceeded to put it in a '78 Malibu coupe, but dumped that project when my son cracked the frame across the rear axle.

It's hanging around the garage, somewhere, 31k actual miles, waiting for a good home.

[TurboDiverArt]

Art, You did a great job and for far less $$$ than my smaller CA/C from B&D and yours looks about twice the size.
Thanks. Core size is 24" across, 12" high and 4" thick, with end tanks it

[TurboDiverArt]

Yep, I see now - I totally missed your response to rj, so I was just repeating you.

Nice installation, btw.

I installed a late '86 GN engine, with the GNX ECM and associated electronics upgrades, in a Mitsubishi Starion, but insurance hassles terminated the project, then MHI put the DOHC 3.4 engine in the Trooper, so the GN 3.8ohv project became pointless.

Then proceeded to put it in a '78 Malibu coupe, but dumped that project when my son cracked the frame across the rear axle.

It's hanging around the garage, somewhere, 31k actual miles, waiting for a good home.
I know a couple of people that have done conversions into 280z's, Opal

[gmctd]

Neat stuff.

What turbos are you running on the 9sec and the 11sec cars?

Wish the PM option functioned over here - helps prevent hi-jacking threads.

[More Power]

Wish the PM option functioned over here - helps prevent hi-jacking threads.

We've had it here since late February when we upgraded to vBulletin..... :)

Jim

[gmctd]

Well.........I may be slow, but I'm dumb ;)

Thanks, Jim

[ronniejoe]

Wish the PM option functioned over here - helps prevent hi-jacking threads.

;) It Does!

[gmctd]

Thanks, rj - come to think of it, seems like I remember Tim saying that he had sent messages here, on occasion.

Maybe it was that replying required a seperate screen, rather than having the response block appear below the posts in the thread.

But, I like this style forum layout.

[TurboDiverArt]

Neat stuff.

What turbos are you running on the 9sec and the 11sec cars?

Wish the PM option functioned over here - helps prevent hi-jacking threads.
The racecar runs a T-82 turbo, it's huge. The street car has a stock appearing TA-52, 52mm turbo with a GT-350 wheel.

Went 9.20 @149.85MPH this weekend in Norwalk Ohio to take the win in the turbo street outlaw class. I qualified third, my car was running very consistent and I cut some good lights off the pro-tree. The class is a heads up class, not brackets so there really is no room for mistakes.

Art.

[TurboDiverArt]

Back on topic for a minute. I towed the whole way out at 70-75 towing the trailer. Up hills and the EGT's were great. Even when the transmission kicked down for a long time on a long hill, maintaining 2800-3000 RPM's at 7-8 psi of boost the EGT's only once entered the 800's and only hit 815. On flat driving the EGT's were about 380-450 almost the entire time. On gradual hills I was in the low 500's. This is night and day from the last time I towed out to the same place and I had to lift on many of the hills and crawl up just to keep the EGT's below 950 (post turbo). This intercooler is the best money I have ever spent on the truck!

I will tell you this though. The black rubber hoses don't do too well at high boost. I have the 3.5" on my racecar and after about 15 passes I blew one of them apart at 24 psi of boost. The 3.5's have a larger surface area so are probably experiencing more stress than the smaller ones at the same boost level. After I blew the upper up, one of my friends commented that he saw the lower expanding to what he described as about 8 inches in diameter. I quickly reinforced the elbows with multiple 4" hose clamps spaced an inch apart. I only had one extra silicone 90-degree elbow which I used to replace the blown out upper black rubber elbow that blew. I was already using silicone on the hot side of the intercooler but was using black rubber for most connections on the cold side (except the connection to the throttle body). My MAT

[Shikaroka]

It's on the Peninsular site, under 6.5 parts - they listed all the new pull-off parts not needed in the marine conversions.

http://www.peninsularengine.com/hummer.htm#17 - intake adaptor - it's oem factory part.

Where do you find parts on their site? I can't find anything.