Hey y’all, I have a few questions about some turbo options. 1. Is BB really necessary and worth the extra money? I’ve read numerous times that apparently they do spool quicker but is it something I’m really going to notice over JB? I’m about to purchase a new precision gen 2 5558 BB or gen 1 5858 JB, just not sure if the gen 2 5558 is worth all the extra money for a street car. Question 2. Since I can’t seem to find the correct info I’m looking for, I’d like to know what size housing to get. I’m debating on the E cover or SP cover, Is there a size difference other than the obvious inlet/ outlet? Any reason to go one over the other besides the anti surge? Keep in mind, this turbo is for a 96 ek d16y8. Maybe I need a B cover for fitment reasons, I’m not sure and that’s where I’m hoping you all come in. I’m really really tired of wasting money on all the wrong parts, I can do all the research I want and still come up short some how. Thanks In advance.

 

The B cover is usually for air conditioner compatible manifolds where the compressor side of the turbo is really close to the block on the transmission side of the engine, and sometimes requires part of the block webbing to be trimmed inwards to fit the compressor in that space.
So it depends on how your exhaust manifold situates your turbo. If you have the exhaust/downpipe on the transmission side of the engine, and not the air conditioner compressor side of the engine (accessory side), then you’ll probably be fine with a E or S size housing because that places the compressor of the turbo farther away from the block.
For example, I think if you have the Inline Pro or other similar cast manifold with A/C, then your downpipe has to clear going near the air conditioner compressor, so your compressor of the turbo goes too close to the block, needing a B cover. But I think people may have trimmed the block a lot and maybe fit a E cover…

 

Thanks for the quick reply on cover size highschooler. Right now I have a ram horn manifold and currently don’t have AC as the ram horn placed the turbo in a manner to which I can’t fit the compressor. I do plan though to buy a speed factory top mount manifold, but I don’t know yet if that will allow me to fit the AC compressor back on or not.

 

Are you planning on buying the top mount hoping that it will work with AC or for power gains? You can reach 500whp with a ramhorn style.
With a top mount, I don’t think you are limited to a B sized compressor in any situation that I know of, and E will work, but I’m not positive about an S. With a Ramhorn, you’d only be limited to a B size if your turbo is situated with the compressor side of the turbo near the labeled part “D16”.
I don’t think you can make 500whp with a B sized compressor. You can with a larger E or for sure the S. So if you go E, don’t get a smaller A/R turbine.

 

Honestly, I just wanted to go top mount for aesthetics at first, turbo on top looks better to me. But now you have me realizing it’s going to be necessary maybe to not be stuck with a B cover. Anything larger than what I have now definitely will not fit as the current charger is almost in contact with the block as it is and in no way will meet my hp goals. Also, another issue I have run into is the routing of my 10AN lines for the catch can. Only possible option I have due to my engine cage is routing them from the front of the valve cover. Problem with that, is the ram horn is much to close to route the lines that way also, so top mount will also aid in that. Again, as I stated before, I’ve already spent a ton of money going completely in the wrong direction, I’m buying everything twice now if not for the third time and I have to get it right this time. 😩

 

Don't buy a Precision JB, they're trash. I've had two CHRA failures within 10K miles on Precision JB's.

Anti surge housing is nice but not a replacement for a proper blow off valve. I wouldn't focus too much on that.

 

Well, on that note, is JB just out all together or just with precision? If Garrett or Borg has an equal option in JB for a precision 5858, is there one you can recommend? And yeah, I’m not too concerned with anti surge, I’m mostly concerned about the size of the covers. Just want to make sure I won’t have fitment issues even I end up sticking with a tucked turbo. I’m pretty sure B, E, or S will be fine with a top mount but I don’t know that for certain yet either.

 

The only BorgWarner I've ever used was an old S256 "Bullseye" JB turbo, and that one was great while I had it. Not the fastest spool but good transitions and I had no issues at all with it while it was on the car. I've heard very good things about their 360 "thrust" bearings or whatever they are, been awhile since I've looked into them but they're supposed to be one of the best JB options you can get.

Garrett JB should also be fine, it's Precision specifically that I would avoid with their journal bearing options... I think there's a couple other people on here besides me who have had negative experiences with those. I'll let someone else chime in on the compressor cover, I've never run a top mount and I don't remember what the best options are.

Edit: For what it's worth, I'd actually still be running a Borgwarner turbo on my current build if space would allow it - an EFR series. My literal only gripe about Borgs is they tend to just be physically large turbos with the way they design their housings and CHRA, so on applications where space is an issue you may have problems fitting a larger Borg.

 

If you are able to have more space for the catch can lines with a top mount, then it might be worth it, if you have considered all other options for catch can routing.
With the turbo almost hitting the block with the ramhorn, I think there would be space to flip the turbo around opposite to where the exhaust side is on the transmission side and make a down pipe that fits that side. But then you’d still have the catch can line issue.
A mini ram horn should work for 500whp, but probably wouldn’t support a whole lot more than that… maybe up to 600 or so, but you’re only interested in 500, so…
You could check out the group called D series on Facebook, and maybe you could find someone with a set up that you could basically copy.
I saw a D16Z6 last week in person that had a full ramhorn and power steering, and no catch can problems, and the exhaust was on the transmission side. Ramhorns are different though, sometimes they are more flat, and sometimes they stick straight up more. The one I saw was more flat. Maybe your ramhorn is really close to vertical and is near the valve cover.
If you do go with the Speedfactory top mount, they seem to work with people more if they manufacture a part, but when I asked them about a part by another manufacturer, they didn’t have much to say. Try calling Speedfactory about this issue.

 

One thing to think about when considering a top mount manifold - that's a lot of surface area to radiate heat from, and you could face cooling issues if this is a street car. I would definitely consider having the manifold ceramic coated or wrap it and run a turbo blanket. I believe you can make over 500 hp with a mini-ram and a B-cover turbo if you chose one of the more modern design turbos like the G25 or G30 series from Garrett (or the knock-off versions from Pulsar). I have not run a mini-ram, but have heard oil return line routing can be challenging, since they place the turbo low.