Twins Questions

[PToombs]

OK, I'm thinking about going with a set of twins to burn some more of the fuel I spew out the exhaust. I have a few questions and may add a few more as I get answers. I did some searching, but we know how that goes.
I'd like to use my hybid H1C, 60mm 6 blade wheel, 16cm exhaust housing, and an HT3B. I have access to that and an HT4B, but I think that's waayyyyy too big, just from looking at it.

#1, Can I use my 16 cm housing, or go to a 12cm with a wastegate? Do I need a wastegate?
#2, I think the HT3B (off a cummins 855) has a 26cm exhaust housing, is this good or do I need a 23cm?
#3, air filter, is a BHAF enough, or do I need something bigger?

I'll start with those. I had a couple more, but can't remember them now.

[dazedandconfused]

From my research you will want the smaller housing on the Ht3b and waste gates on both for tuning. External wastegates seem to be the best for tuning from what I've read. I have no idea on the secondary's exhaust housing though.

[oldestof11]

To use the low end fueling the VE likes, a quick spooling setup is best.

Personally, 12cm hybrid and a 23cm HT3B. The internal gate on the hybrid ported and an external on the hot pipe between the 2 if the exhaust drive pressure/boost exceeds 2:1. Otherwise I think you will be fine.

I cant remember... Do you have the hybrid done already or needing to do it? If you need to do it, I wouldn't touch it. The secondary just increases the pressure ratio and a 57mm can support upwards of 600-700hp with the 3B. If it is already done, then don't mess with it.

[The_Head]

Can you swap out exhaust housings on HT3B's like you can on some other turbos? Mine has a 26, might go to 23 if it is relatively easy and not too expensive.

[oldestof11]

They came in 2 flavors iirc. 26 and 23cm's...

[The_Head]

It's probably not worth the effort to go from 26 to 23... kind of like going from 18.5 to a 16 on an H1C?

[oldestof11]

I would think it would be more so. Like going from 21 to 16. You need that big one doing more work. Let me see if I can find some concrete info. I remember thinking that since it is the 2nd stage in the exhaust, then changing housings was like 2x steps tighter...

[PToombs]

Jon, the hybrid with the 16 is on it now. I have an HX 35 in the barn with a WG housing, pretty sure it's a 12cm.

[oldestof11]

Pete, you good with math?

Here is the info I am using on compounding turbos.

http://www.vwdiesel.net/forum/index.php?topic=28781.0

I would use the hybrid and put the 12cm on it with a ported W/G divider.

[PToombs]

Is math that siht with the numbers? I hate that stuff!

I'll look around on there, thanks.

[PToombs]

Jon, I have no clue what the heck he's talking about. He lists those units, VE, BFSR, and the other one, and I can't find any reference to what he's talking about. As Bill would say,
FAIL!

[oldestof11]

Google is your friend Pete!

Garrett has an EXCELLENT site on how to map these things. But the main thing I was getting at is achieving the best PR (pressure ratio) for the hybrid.

http://www.turbobygarrett.com/turbobyga ... enter.html

VE= Volumetric Efficiency, around 75-85% for a Cummins due to the restrictive head.
BSFC= Brake Specific Fuel Consumption. On a moderately fueled Dmax, it's around .38...
AFR = Air Fuel Ratio, diesels tend to be between 17.0-18.0:1 on a diesel
PR = Pressure Ratios, one side of the turbo map.

Hope this helps a bit.

With all that being said, this is a scientific way of finding out. Why not ask Bill what he has?

[bgilbert]

With all that being said, this is a scientific way of finding out. Why not ask Bill what he has?

I was just thinking of asking why Pete didn't bring up the topic of twins at SOP..

[pulltilbroke]

With all that being said, this is a scientific way of finding out. Why not ask Bill what he has?

I was just thinking of asking why Pete didn't bring up the topic of twins at SOP..

My thoughts too Bill, I know there were 2 guys there with experiance tuning twins

[PToombs]

I kinda forgot all about it. I did talk to Matt briefly, he said he'll do the pipes for me, but since then I've been thinking about it and came up with these questions. Andrew, who's the other guy?
Plus, it's nice to be quiet about it and open the hood next fall and have people go, WOW!

Jon, I know what Bill was going to put on, but I'm not buying a S400 turbo when I have a HT3B sitting here for a paperweight.