I know I know these threads get old fast but I am honestly in a pickle regarding what I should do! I don't do a whole lot of towing but when I do it will get up to about 10k and it is usually for long periods of time (a few hours or so). I NEVER get much above sea level, the hills on the way up to Tulsa OK are as high as it gets. I have 3.55's and 35" tires also. My biggest dilema comes from the fact I want 600rwhp on #2 only, this has been my goal all along. And I daily drive my truck so the less lag the better obviously.

My choices I think are...

1. HTT 62/71/16 Stainless as a single
2. HX35/NWG14 and BHT3B/26 twinset with a 40mm external wastegate bypassing the 35.
3. HX40/14 and BHT3B/26 twinset with enlarged internal wastegate.

Like I said I daily drive the truck and do tow occasionally for long distances and I want 600rwhp on #2 only. I know there have been several people make 520-540rwhp on #2 with a SPS62/14, like Forrest made 535 with a ported head and 18.5* so could the #1 choice maybe do 600 with a tad more timing?

And to make things even worse later on down the road I want to add Nitrous possibly lol.

Also I am going to bump my timing to about 20* after the head is on. So what do you guys think out of these options would be the best idea? And is there any other possiblities out there? Thanks everyone!

 

Towing with 35s and 3.55 gears completely rules out a single charger imo, unless you are going to tow at 300hp or so and use the stock charger.

You're talking about high loads at low RPM, meaning you need a turbo that gets into the boost way early.

To me, that means stock charger (or smaller!) with something hung underneath it. A Stocker with a K31, GT4202, or S472 should all work well with the stock charger. You'll need a larger external gate for bypassing the small top charger, and you'll probably want to wastegate the bottom charger, too-- which favors the K31, imo.

Justin

 

Thanks Hohn! When in tow I will be in valet mode, I'm hoping to just be from 350-400hp then. Thinking about it 10k in tow would probably not happen ever again since I am getting out of the hay business lol. In that case I think 5k would be tops...

I also did a pretty good port job IMO, lots of blending and smooth flow down in the bowl on the cylinder head. I would think that would help quite a bit... Keep it comming

 

I use combo #2 right now. I have a hx35/14 nwg housing with a ht3b/26 . I tow heavy for hours, with 3.54's but with 235 tires and a 6 speed nv5600. I use 5th most towing at about 66 mph at around 25500 lbs. Ive been heavier and lighter. It works great and I m at 2200 ft or higher. Da is ussually 4000-6000 ft. It runs great at sea level (so cal). I actually have been planning a change though. I overspeed the hx35.....so I picked up a three peice manifold , ported it and had it coated. I have a 50 mm waist gate to ad in a spacer I need to make to bypass the 35 turbo. I ve been told that will not help the 35 issue though, and I really need a larger turbo. This is an experiment so I figure a 35/40 or 40 may be the way to go....I m going to do it soon as dune season is nearing and I want it done before that since we go alot and it sees a lot of road miles over the winter.

If I could just get a decent deal on decent turbo.....or Ill just rebuild the 35 since it works great.

 

Do twins, you wont be satisfied trying to accomplish what you want with a single.

 

So which twin combo should I use guys? Remember I have to have 600+ on #2 only lol.

 

Don't kid yourself that must because a single can put up the big dyno numbers means it makes that at a streetable RPM range.

The huge disadvantage in "area under the curve" of a larger single (even a 62mm size) compared to twins means towing is a lot less friendly-- more downshifting and a lot easier to lug.

Since you won't be towing heavy anymore, you won't need a 35 on top in twins-- you could do a 40. But the huge wg on the HTT turbos (stainless) could almost completely eliminate the need for an external gate on top.

So maybe you'd be wise to consider a ss62/71/13 on top and save the cost of the external gate and plumbing.

Lately I've become intrigued by the idea of using a really largish (but not too large) hot side on the top charger. Something like a Silver 62 or ss62/71/16ss. The idea is to reduce restriction to the larger charger and keep drive pressure as low as possible relative to boost. Also, since we're not trying to drive the top charger superhard, we can use that larger hotside to improve efficiency because it will make more heat and pressure available to drive the bottom turbo. It will also reduce the amount of gasses that bypass the top turbine and allow you to get by with a little less wastegate capacity (making sure that your internal gate would be enough).

I mean, a Silver 62 is crazy expensive at $2k for a single. But compared to a $1600 top charger, an external gate and the extra plumbing, you might actually save money.

I'm thinking that for all the efficiency though, it would be miserably laggy to drive, and defeat the whole point of doing twins.

jmo