Very small 12 valve tow twins

madmikeismad

madmikeismad

So mad
I'm starting to haul enough where my single 67 just doesn't cut it down low, especially starting up hill and short entrance ramps on the highway. So my thought is to swap it to a 1.1 or larger housing, and make it a primary, with a 58mm secondary or something similar. Figure it would spool super fast, clear up some low end haze, and with that larger housing it should still be able to do 600hp easy.

Am I an idiot for this? Is there a chance they would light too quick and bend a rod? If I don't do this, I'm going back with my original 63 over 78 plans.
 
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diesel_importer said:
I've wondered the same thing Mike! In theory, it sounds awesome, especially if it'd spool around 1600-1700 rom
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Thats about where my 67 spools now, I'd like to get it a little lower. I love this 67 though, egt's are NEVER over 1200*, and once it's moving 23k is nothing. I'm going to reset my timing to exactly 18* first and see how that helps, but I don't think it will put me where I want to be.
 
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for reference, the bd towing twin setup is a 66/73/.91, I see no reason why your charger with a different exhaust housing would not work.
 
Hurley said:
for reference, the bd towing twin setup is a 66/73/.91, I see no reason why your charger with a different exhaust housing would not work.
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Yeah, I'm more concerned about the secondary, I'm not very turbo intelligent. But I was hoping a 58 wouldn't choke it too much. I really want to keep the truck over 600. 700 would be great but I know running in a compound setup will limit max hp a little compared to a single.

I guess my main question, is what will a 58mm support as a secondary?

Also, I'm thinking I might retain the spool flange.....
 
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The BD towing twins will not break 600 HP to the tire fuel only. Lots of guys tried back in the day and the most I ever saw was 590 HP.

If I were in your shoes, I'd pick up an HX35, HE341, or HE351 and build a set of junkyard twins using an HT3B, HT60, GT4202, S472, S475, K31, or similar and have yourself a nice towing setup, capable of 600-650 HP, and spool-up like a stock truck!!!

If money wasn't an issue, I'd do an HE351 over S475.
 
He351 with the 67 should be an amazing setup for towing. When I had my 351 and gt55 I would have 10 psi at 1500 and 20 at 1700. Then vroom LOL
 
Big Blue24 said:
The BD towing twins will not break 600 HP to the tire fuel only. Lots of guys tried back in the day and the most I ever saw was 590 HP.

If I were in your shoes, I'd pick up an HX35, HE341, or HE351 and build a set of junkyard twins using an HT3B, HT60, GT4202, S472, S475, K31, or similar and have yourself a nice towing setup, capable of 600-650 HP, and spool-up like a stock truck!!!

If money wasn't an issue, I'd do an HE351 over S475.
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x2

I loved my hx40/475 on my old 12v...super fun to drive, and always ran clean.

Any of those turbos listed above are fairly cheap, which is always a plus.
 
I made 601 with my A3K/A5K (57mm/71mm) on a 160hp pump, and it tows awesome. Do it....it's ridiculously drivable.
 
To all saying that that I should run a bigger primary, I'm banking on the 67 flowing 95 lb/min. Maybe I'll run a 60mm secondary then. I just really want to keep it over 600hp, as a matter of pride. And I already have a 67 and will never be able to sell it for what I have into it.

Also, I know crap about the 341/351 stuff. If its anything variable then I won't have the skill to set it up.

I'll rephrase again because I'm terrible with getting my thoughts into words : I want the fastest spooling secondary possible that will do a proven 650hp.
 
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What does your truck dyno now? I lost 30hp with twins.

Edit: at the same boost level, with the same amount of fuel. The twins were later capable of more boost and supporting a lot more fuel without getting into EGT trouble.
 
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JQmile said:
What does your truck dyno now? I lost 30hp with twins.

Edit: at the same boost level, with the same amount of fuel. The twins were later capable of more boost and supporting a lot more fuel without getting into EGT trouble.
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Last dyno was 623 @ 48psi and 1200*, unloaded, with boost leaks and only God knows what timing.

Thats why I think with a capable secondary, the 67 with a larger exhaust housing will still do 600-650 as long as it doesn't get choked by the secondary especially once I swap to 13mm p&b. I guess I wouldn't mind a small drop in HP because I know it'd be picking up gobs of torque.
 
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mike the he351cw's are not electronic or variable.... has a super hx40 compressor wheel a decent flowing internal gate and a 9cm housing.
 
As long as the small charger has even a decent internal wastegate, I wouldn't worry about it. Buddy of mine has 3 1st gen HC1's (50mm) and gets 70psi out of that setup.
 
Forrest Nearing said:
don't worry about a bigger primary... bigger is not always better. especially for towing
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I'm not, just the exhaust side. I'm not going huge, just don't want the .91 to be the limiting factor. Be nice to keep the EGT's a little happier too.

Lostnwalmart said:
mike the he351cw's are not electronic or variable.... has a super hx40 compressor wheel a decent flowing internal gate and a 9cm housing.
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super 40 was a 60mm right? T3? I'd like to keep to a T4 setup.

JQmile said:
As long as the small charger has even a decent internal wastegate, I wouldn't worry about it. Buddy of mine has 3 1st gen HC1's (50mm) and gets 70psi out of that setup.
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I'm not worried about exhaust side, that can always be gated, just don't want the physical size of the compressor to limit anything.
 
Definately interested to see how this goes for you. Might be something to do in the future for my new tow rig. Oh and keep me in mind if you decide to sell the 67.7
 
351 with a 1 inch spring wastegate works great on the street. With the convertor locked I can make 30 lbs. of boost a 1500 rpms. I have to be a little gentle taking off to not create to much smoke but I have a very tight convertor which doesn't help. I 341 will spool a 10 or so rpms sooner seems to choke more on the top end.
 
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