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Discussion Starter #1 (Edited)
Disclaimer: It is your truck and your turbos. If you mess anything up it is your fault and this is serving only as a guide. That said, usually it is pretty hard to mess something up internally in your engine by messing with turbos. It will either perform or not perform...

I have edited this a little bit to be a little more clear and show there are multiple options for turbo mods... This is all based on some of the turbo swapping/tinkering I did to get better all around streetable and highway performance, without trying to lose any fuel efficiency. In fact I gained some efficiency to an extent. Most of these mods are for up to 160 to maybe 200 hp I would estimate max, which in my opinion is more than enough to power most of our vehicles very well in my opinion...


EDIT: - There are some things I didn't know, like some fords have low/dropped mount turbos like the GM 4BTs.. Also, there are different HX335 turbos, that look slightly different... So, I am making edits to the original stuff as I am picking up new things from your posts. So post up corrections and clarifications!



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I have listed my recommendations for turbo mods as "options," as these are most common & easiest performance modifications. They are listed in order of most power/overall efficiency/performance. Option 1 > Option 2 > Option 3. Except, that it is possible that option 2 would be better for "bombers" rather than option 1.

FIRST:
What comes on our 4BTs is this (usually):
GM step vans: H1C turbo, 16cm2 non wastegated housing
Ford: H1C turbo, 18.5cm2 non wastegated housing
Photos of the stock H1C setups are posted below...

There are other variants and weird turbos, especially with 4BT gensets etc, so what is above is not always the case, just "usually" is...

There is nothing wrong with H1C turbos and in fact the best bang/$$ / easiest turn key modification for the 4BT is simply replace the exhaust housing with a smaller one. This is discussed below and is option #3 below.


OTHER NOTES ABOUT TURBOS & POWER:

The way diesels work is FUEL=POWER. Because we are ramming air in with turbos, you want to try to match the amount of fuel you have with the amount of air you have. This is how we are able to get these larger amounts of power out of these semi-small engines. The stock turbos can only make certain amounts of power in certain power ranges, so if we increase the amount of fuel we have, we must increasing the amount of air to the engine to match it, which equals increased power. You can also get a lot of power out of simply turning up the fuel, but you may lose some efficiency with unburnt fuel (black smoke).

Stock injectors are actually pretty good but to get real power (beyond what we are discussing here), increased injector size (Lucas POD "Prince of Darness" and the Bosch 190 injectors that PiersDiesel.com also sells are good injectors and are available for 4BT models) combined with increased air is where the real power comes from, for those seeking 200hp or higher. I personally am very satisfied with 130-160hp out of a 4BT and fine it runs excellently without compromising efficiency, and currently run stock injectors. That said, bigger injectors combined with a good turbo setup may be even better even at lower HP levels, I dunno...


TURBO OPTION 1: The HY35 turbo


People on www.Turbodieselregister.com first though the HY35 would be a good turbo for a 4BT. Is is basically the smallest exhaust housing with the biggest turbo Dodge/Cummins has put on any B series I am aware of...

The HY35 is a 9cm2 housing, wastegated... The way a wastegate works (see pic) is a little flap before the exhaust that lets extra exhaust BYPASS the exhaust turbo propeller. This is a great way to get boost fast from a small exhaust housing like a 9cm2, but it lets off extra pressure at higher RPMs. The HY35 is designed to start opening the wastegate around 18psi or around there...

I haven't run this particular turbo yet but plan to so I have no direct experience, but I do own one and plan to use it as soon as my new truck is running. DriversWanted on TDR and a handful of other people do and they all like them a lot and all say they work pretty well.. The Dodge guys who bomb their trucks are eager to pull them off as these turbos and exhaust housings are too small for serious 5.9 performance at higher RPMs. So they can be had used pretty reasonably. I got mine for about $250 shipped off Turbo Diesel Register classifieds (which are open to anyone), http://www.turbodieselregister.com/cgi-bin/classifieds2/classifieds.cgi
I think anywhere from $200-$350 is pretty good for a HY35 in my opinion.

There also seems to be a lot of "HY35" models on ebay that are not HY35s. Most look similar, but can't say for sure if they are variants or later models?

Anyway, photos here show what a HY35 looks like...
 

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Discussion Starter #2 (Edited)
More photos of the HY35. Key distinction for the HY35's is the casting in the compressor side of the turbo has the built in mount for the wastegate actuator, whereas most other wastegated turbos have a "hanging" or different waste gate actuator setup...
 

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Discussion Starter #3 (Edited)
More photos of a HY35... This is my actual turbo which I took it apart completely as I replaced the compressor housing with a nice clean one that I bought that had been sandblasted. You can see actual turbo for what its worth, and see wastegate flap open...
 

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Discussion Starter #4 (Edited)
More... You can see how I took off compressor and exhaust housings. Nothing wrong with this as long as you are mildly careful/don't drop the turbo as it can bend the fins...
 

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Discussion Starter #5 (Edited)
OPTION 2: a HX35 or a WH1C turbo

Option 2 is basically a "HX35" turbo.. See the chart below for a list of years and applications they came on...
I believe the HY35s are pretty similar to the HX35's but with a larger 12cm2 exhaust housing, and some cosmetic differences suchas a different wastegate actuator setup. Both these, and the HY35s have a larger impeller (correct terminology "compressor wheel") and as a result have a slightly larger air intake tube of 4" instead of the 3" tubes our stock H1C turbos have.

Because of the 12cm2 housing, they breath a little better on the highway and haver lower overall EGTs on the highway, but less spoolup at lower rpms. Smoking: not much when turned up to match the turbo. When I ran this turbo, I turned up my pump, it smoked a little bit on acceleration until the turbo caught up. I think you would actually get less overall smoke and slightly better performance out of a HY35 but a HX35 is a very viable option that works well. Both physically are about the same size.

The way I achieved my "HX35" was actually by using a WH1C, which is basically a nearly identical turbo. Almost everything is the same, including the waste gate actuator linkage. My head gasket was going bad on a long road trip so I was running high EGTs and killed a seal in my stock H1C... So I bought a replacement, again used off the turbo diesel register classifieds, which are free and open to anyone, and what showed up was this weird '94-only WH1C. It was a blessing in disguise as I thought I had ordered another H1C.

1994 was when Cummins started getting in the power wars and their solution was more turbo, faster spool up off the getgo then the wastegate to prevent overboosting and maintain good highway efficiency/low towing EGTs. This is testament to the technique of simply adding more air with fuel for more power, the difference in power between '89 and '97 Dodge is amazing, and they are not that different mechanically.

According to TDR they were planning on discontinuing the H1C style turbos (which work fine, not sure why they discontinued) in favor or larger turbos. But because they wanted to be more competitive, they made the WH1C for one year only, before redesigning it completely and introducing the HX35 with basically the same specs. The WH1C and HX35 are pretty much the same turbo characteristics, very similar technically and parts interchangable with our H1Cs but with the performance/dynamics of a HX35s, so this is how I know a HX35 also works well with a 4BT. It is a 12cm2 wastegated housing, with a larger impeller... 4" intake tube versus our 3" intake tubes on the 4BTs. I believe 6BT intake tubes on intercooled H1Cs are also 4". No big deal, I adapted it back to 3" using a "cobrahead" (nicknamed after how the adapter appears) from www.intakehoses.com

The wastegate actuator also wouldn't fit with my HX35/WH1C (FROM A 12VALVE; 24 VALVE HX35's look almost identical to a HY35 and fit fine) with the 4BT Chevy style dropped manifold. It would with a Ford high mount exhaust manifold or a trimmed and capped 6BT manifold (posted below). So I bought a 12cm2 NON wastegated housing from Gillett Diesel Service in Salt Lake City (http://www.gdsdieselparts.com/) for $150 and it worked great... Top boost was about 20 psi, higher ever was about 25psi. WH1Cs with their stock wastegates open at about 18 psi so I barely would have touched it at this point.

Wastegastes also open gradually. So just because it "opens" at 18 psi does not mean that it the top PSI range.

Having this bigger turbo, with stock injectors, was almost like night and day particularly on the highway... Much better performance. I found my stock H1C was great but once I got a 3" exhaust on it did not spool as well and I lost power. The WH1C cured that... The only reason I don't have this turbo any more is because I sold the truck with the motor it was on. But over all, I was VERY pleased with this setup...

Here are photos of it with the stock WH1C 12cm2 wastegated housing, that will need to be replaced with a 12cm2 NON wastegated housing if you want to install it on a Chevy dropped intake. If you score a HX35 from a 12 valve, it should bolt right up and looks almost identical to the HY35 pics above. I will post HX35's pics of a 24 valve later...
 

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Discussion Starter #6 (Edited)
OPTION 3: STOCK H1C turbo, but with a smaller exhaust housing

A lot of guys have done this on these forums I believe, particularly the Bronco guys with 4BTs.

Here is a photo of the stock 4BT H1C off a chevy style manifold with the drop mount.. Good low location and turbos will fit down there but I had to do firewall modification when I installed it...

This is a great turbo, it is a little small, but spools up very well. By far, the easiest/best bang for the buck is simply a smaller exhaust housing. It costs about probably ~$180 shipped from anywhere suchas Gillett Diesel Service. Most places that carry these think in "Dodge" so you can say the same turbo as a "Gen 1" (1989-1993) Dodge. You want a 12cm2 NON wastegated housing or a 9cm2 non wastegated housing. The reason you don't need a wastegate, versus a HY35 which has a 9cm2 wastegated housing, is because you have a smaller compressor wheel/impeller with the 4BT turbos. This is actually a good thing. A 9cm2 is the best overall performance for quicker spoolup and acceleration, with some compromise of higher boost levels at highway speed and possibly higher EGTs. The 12cm2 non wastegated housing is a little more freeflowing so lower EGts on the highway, but less around town off the line acceleration.

The non wastegated housings I have seen are literally identical to the exhaust housing you will be removing, other than its obviously smaller turbine housing. Some housings move exhaust back 1" while others are the same... All wastegated housings are the 1" farther back to allow for room for the wastegate. I have heard rumors of some non wastegated housings also being 1" farther back, not sure why they do this. For this reason I would say do not cut out or plan to move your exhaust until the housing shows up. I did this, and ended up rewelding everything back exactly the way it was...

The housings are made by Holset so they are all OEM...
 

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Discussion Starter #7

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Here are photos of the 4BT Ford bread truck high mount turbo. All of the exhaust manifolds/turbos/ etc are all for the most part interchangable. Big difference between the GM and Ford as far as fitment goes is the OIL FILTER MOUNT. On the Fords it is taller and a vertical hanging filter. This will fit with the modified Dodge 6BT mounts (previous post) as Dodges also have vertical mounts. I am 95% sure the Dodge 6BT filter mount will also fit on a 4BT if you want a bigger oil filter, not sure if there are bigger advantages/drawbacks to that or not). The GM oil filter mount is horizonally mounted and sits sort of low. This is because with the GM dropped turbo, the intake is where the verical filter would normally go. The vertical filter is of course preferred as it won't drain out and doesn't make a mess when you remove it..

Anyway, the Ford high mount turbo setup...
 

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Discussion Starter #9
Here is the Ford Manifold, same turbo as previous post... It is high and centered...

Also, this engine came out of a GM P-30 and I installed the Ford setup on it as I thought it might fit better than my GM setup. People often want the GM setup when they have a ford, and vice versa. This is what the classifieds section is for :smile:.
 

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Discussion Starter #10
Chart of the different turbos off different years and their characteristics.
 

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Here are the Ford and Chevy style filter mounts. Again they are removable and interchangeable... Photo of the complete engine is from JBfab.net , that is a HY35 on a funky Ford manifold that I have never seen before...
 

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I too think the HY35 would be a better turbo for the 4BT. I think I have found one. If not I may try the HX35/12 that was on my Dodge. I am going to try to post pics of the low mount from my E350 donor. Notice the NP435!:smile:
 

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Discussion Starter #14
odd a ford with a low mount and a NP435?
 

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Discussion Starter #15
Here are photos of what I had to do with my firewall to get my turbo to fit with the Chevy style dropped manifold... This is mostly FYI. Also, if you are switching housings, this is why it is helpful to have the OEM style non wastegated exhaust housings as they are 1" shorter for their exhaust manifold mounting pattern...
 

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Discussion Starter #16 (Edited)
RE: "Option2" Here are photos of an actual HX35 turbo from a 12 valve. You can see it is identical to the photos of the WH1C turbo posted earlier...
 

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Discussion Starter #17
Here are photos of different flanges for different wastegated turbos. You can see there are band and cast downpipe style flanges that bolt to the different turbo housings.. They are interchangable as well...

In the picture of all the crap, look in the top left...
 

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Discussion Starter #18
RE: Option 1, better pictures of a HY35, complete..
 

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I put an hy/9 on my 4BT intercooled setup. I welded the wastegate shut. With the 3200 gov spring I hit about 28psi with no EGT issues which is pretty fun. I also took out the silencer ring to the thing whistles like crazy.
 

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flandes

if you swap in a hx/hy35 for the h1, does it bolt up? do you need different flanges to mount it up? what about the wastegate, is it vac. acctuated?

thanks for any info.......getting close to swap and am thinking real hard about this
 
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