Engine/Transmission (1994 - 1998) DPS Twins & Ball Bearing Turbo

[MMcCallie]

My Garrett Stage 2 PowerMax has been making noise for a couple years so I need to rebuild or replace it soon. I've always known a single turbo was not a permanent solution to my turbo needs but fitting two turbos is hard to envision with how little space there is with the 12 valve being in a Ford Excursion.

I haven't found anyone able to rebuild or modify my PowerMax since Garrett dropped the line years ago. With my fueling I need a lot more airflow to reduce my EGTs but due to the weight of the truck, gearing, and tire size I definitely need my turbo to light sooner. I expect compound turbos is my only option.

DPS (Diesel Power Source) has a twins kit designed to fit in Fords with a Cummins, which they call their Fummins Twins kit. In other TDR sections I've seen excellent reviews of their kit for the Cummins but most of those posts are nearly a decade old so it would be great to get some current thoughts after years of field use.

The DPS Fummins Twins looks like the only kit I can possibly make work because their compressor housings have a 45 degree elbow, which I can't find as an option on any other turbos. They use an S300/S400 setup in various sizes with 360 degree thrust bearings.

My Garrett is the only turbo I've ever had that doesn't surge. Despite the noise it is very drivable. I would definitely like to stick with a ballbearing turbo for my secondary and DPS came out with one last year, based on the S300. I don't know if they offer their 45 degree housing for their ballbearing turbo. I don't know if they offer a ball bearing upgrade for their S400s either. I am awaiting a reply that will hopefully answer these questions.

Does anyone have experience with their ball bearing turbos? Instead of cooling the turbo with engine coolant like the Garrett, theirs is oil cooled. They have videos of how long their ballbearing turbos continue spinning after shutdown, which appears to be similar to the Garrett, without the noise mine is currently making. They claim that their ballbearing turbos outperform similar Garrett and other brands of ballbearing turbos. I don't know if that means they run cooler, light faster, flow more in the mid or upper range, etc. I couldn't find any compressor maps to compare to my Garrett. I saw a post on another forum claiming several customers had surging issues but don't know if that was resolved.

One major hesitation I have about the DPS Twins kits is that they use a silicone hose between the compressors and all silicone boots and clamps. I had planned to use v-bands but it doesn't look like they offer that option. Has anyone pushing high boost numbers like 70-85 psi that's been running their twins kit for years had any issues with blowing those connections?

I'd be very interested to hear how quickly their kits light with a thrust bearing or ball bearing secondary. I've also read on other forums that their ballbearing turbos don't light nearly as fast as advertised, as low as 1,100 RPMs if I recall correctly.

My Garrett quickly jumps to near 50 psi on a quick hard acceleration like when passing a vehicle on a two lane. EGTs are usually in the 1500 degree range but if I bury the throttle I can easily see over 2,000 degrees. Any advise regarding how big I need to go with my primary? I like the idea of a small S475 to light quicker since most of my driving is at low RPMs, pulling trailers, between stop lights, etc. but reducing EGTs is absolutely necessary as I can not climb hills empty at 60 mph without exceeding 1,250 degrees. Any other thoughts regarding their kits are welcome.

 

[Tinman]

Turbo Re-Source will work on your Garrett. I can't speak to your space limitations, but a Holset HE451VGT came to mind. I read they perform very well and it would be a single - for space. You'd have to have a standalone controller. 451 is a costly change, but so are twins. I've only read about it in the later model trucks.

 

[MMcCallie]

It looks like Fleece Performance has discontinued their VGT controller but Steed has a Banshee II that has good reviews on the forums. I read a thread saying the HE451VGT still has quite a bit of lag and some late model Dodge owners are left wanting compounds even with their variable turbos.

Anyone have experience on what sort of power can be attained with this turbo and how quickly it would spool compared to my ballbearing Garrett? I see Fleece has some upgrade options starting well over $2,000. I would like having an extra exhaust brake. My biggest concern with a VGT is how large they are. I can barely squeeze a finger between my Garrett and the heater box. My PDI manifold tilts the Garrett slightly downward. I would probably need a late model manifold that would drop the turbo to hang closer to straight down.

I heard back from a company that can upgrade my Garrett with a GSX wheel for $895 or an all new CHRA for $1,450. I am trying to get more comparison based information.

DPS is suggesting their ballbearing 62/71 over an S480 that should light close to stock and increase power 18-26% over my single Garrett. That power increase would take me from my 600-ish to at least 700-750 hp with lower EGTs that should drop 250-400 degrees. While they don't offer a v-band upgrade they can build up the beads for higher boost pressures. They said having compounds would eliminate any potential surging issues.

 

[MMcCallie]

I've been able to acquire a little more information regarding how the DPS ballbearing 62/71 over an S480 will perform in that EGTs currently 1,500-1,600 will be 1,100-1,250 compared to my ballbearing Garrett and that I will be able to tow while ascending steep grades without having to drop out of overdrive. That is one of my most important goals. I currently have more than enough power to pull any load in overdrive but my EGTs can't handle it and even dropping into third leaves my EGTs well beyond 1,300 at highway and interstate speeds.

I've tried to find out how spoolup will compare to my current single and unfortunately still don't know if it will be faster or slower, which is causing me significant hesitation. I'm told spooling will be similar to stock, which is hard for me to recall since I haven't run a stock turbo in about a decade.

When I inquired about using a variable turbo with the DPS kit and asked again about using a spool valve I was referred to the DPS blog. I read every article in the blog and found no mention of either. This seems to be a theme, many of my questions remain unanswered. Do other customers have this same experience?

I read of another DPS customer having issues with wastegates repeatedly breaking on their twin kit. IIRC DPS replaced it three times and for the last replacement was provided a used wastegate and told there would be no more warranty replacements. On another thread it looks like some time after that, perhaps years, there was a redesign that fixed whatever was wrong about the previous design.

Hopefully soon I will have a price for their recommended kit. I'm not sure if the exhaust housing on the ballbearing turbo being suggested is a 12 or a 14. Would there be any issues using the 12 cm housing on the secondary with an S480 as the primary?

The upgrade for the ballbearing Garrett Stage 2 PowerMax to a GSX wheel is described as having a seat of the pants improvement, lighting faster, and greatly lowering the peak power RPM range. It sounds like the amount of increase in improvement would still be a bandaid given my EGTs.

If anyone has tried a VGT or VNT over an S475 or S480 on a 12 valve especially, I would be very interested in hearing about its performance. Most of the threads I've read about spool valves are several years old. Several users of the BD Diverter Valve and other brands have had the valves stick closed, resulting in melted turbos. Soot and heat can cause the hinges to fail stuck shut. Most of those I've come across were in racing applications. Daily drivers seem to have much better experiences and absolutely love how quickly they spool. I've read of some truck owners planning to use a spool valve on their secondary turbo but found little information on the results of those projects.

I was hoping to learn if the DPS kit would work with a VGT or a BD Diverter Valve on the ballbearing 62/71. Has anyone tried these with theirs? If the spool valve would work safely and effectively I would probably go with a larger secondary like a 64/71. I asked DPS if I could reuse my PDI three piece exhaust manifold and learned I could not due to clearance issues. I like that they provide three ports for thermocouples and boost ports in their exhaust manifold. I would definitely like to know my drive pressure. My current Garrett has by far the closest to 1:1 of any of the several turbos I've run. To lower my EGTs I've been considering the Banks water injection system as an upgrade to my current water injection. The Banks kit has an option of being programmed from a pyrometer reading so it would be nice to have another port for a second thermocouple.