Cost vs. Benefit of twins? Chime in

[BDR]

I was wondering what everybody’s thoughts were on this? What's needed in a solid twin set-up? Pros and cons? I'm looking for everybody’s thoughts, opinions, ideas, and experiences. Please chime in. Why twins?



I've read a lot, just wondering what everybody thinks about twins.

 

[Hohn]

I was wondering what everybody’s thoughts were on this? What's needed in a solid twin set-up? Pros and cons? I'm looking for everybody’s thoughts, opinions, ideas, and experiences. Please chime in. Why twins?



I've read a lot, just wondering what everybody thinks about twins.

The simple answer is that you get a lot more capability from two turbos sharing workload than from one trying to do it all. A turbo is a lot more efficient (and effective) if it can be designed to loaf at 20-23psi instead of having to trying and belt out 55-60psi. The efficiency map of a turbo that CAN make 60 psiis pretty narrow and difficult to use. On the other hand, a turbo that only has to make 20psi has a MUCH fatter map and more useable range without issues (surge, inefficiency, barking, etc).



So in a twins setup, you can run each turbo in a way where it "sees" a workload of about 20psi-- and end up with 55-60psi of boost. It's FAR more efficient than a single turbo trying to do the same work.



So here's the short version



Twins PROs:

-- efficiency

-- cooling



Twins CONs:

-- Cost

-- much more tuning required

-- higher maintenance

-- perhaps less reliable

-- takes up more space underhood (may lose battery)

-- Slower spoolup





jh

 

[SRadke]

If you're pushing a single too hard, hard enough to blow one (or more) up you've already spent enough money to have done the twins to start with.



-Scott

 

[RonA]

Twins do cost a little more. They spool a little slower than stock, but faster than a single at the same performance level. Tuning is not that hard. Twins will be more reliable than a high performance single. 35/3b twins spool faster than an HX40 and run alot cooler.

 

[Diesel Nut]

I am in this same situation, but I look at it like this-

What do you plan to do with the truck?

I want big power, but have to tow.

What are you willing to spend?

I have seen twins range from 3k to 6K. Thats a lot on coin.

For me, and I have had people pushing twins on me bigtime, I just can't see spending 4-5 grand on turbos when there are so many good singles out there. I agee that twins are the way to go for effiency and turbo life, but the costs are just way up there. Also, depending on the truck and set up, there are other things required with turbos. O-ringing the head or fire rings, head studs, blown head gaskets, and I am sure there are others. I want twins in the worst way but unless they come down in price I will be saving like crazy to move up to a single that is engineered for my application. If you have the wallet, twins are the only way to go. I just don't have the wallet.

 

[Pmaloney]

As to the cost of twins, if you can weld/fabricate a little they are cheap and easy. I built mine myself and could'nt be happier with them. I tow 10k+ through the rockies and it is hard to break 1200 degrees pre-turbos. This is with the mods in signature. Granted I only run the box on 1 or 2 and at the moment I am right foot limiting my boost to 40 or less.

The cost was very low, you figure about 150$ in tubing (including exhaust mods, downpipe), 250$ for a external wastegate, 450$ish for a HT3b turbo, I had my flanges made for 50$, then about another 100$ between silicone connectors/clamps. If you are using a factory turbo this is comparable to the cost of a aftermarket larger turbo.

I know that I will be even happier when I finally figure out how to get that 2 wastegates set correctly Any help here would also be appreciated.

All in all I say the only way to go is twins, plus the sound is to good to describe

 

[swankmetal]

I was wondering what everybody’s thoughts were on this? What's needed in a solid twin set-up? Pros and cons? I'm looking for everybody’s thoughts, opinions, ideas, and experiences. Please chime in. Why twins?



I've read a lot, just wondering what everybody thinks about twins.

cost vs benefit:



good. it's nice NOT being able to get the egt's over 1200. period.



what's needed? another turbo, a wastegate, some exhaust bends, and a 90 from a plumbing store. would you be putting them together yourself? it can be done for a lot less than 3k.



pros:



they sound cool



cons:



they require more attention than a single. big deal, right?



about all i can say is that i will never go back to a single. less neck snapping and more checking the seat mounts.



dave

 

[swankmetal]

patrick, glad to hear they're working out for you. i'm loving mine.

 

[RonA]

I have talked to alot of turbo shops lately looking at different primary turbos. Everyone is pushing the S300 variations. They say that a 3rd gen spools so well that with 66mm version,twins are a waste. So maybe spending 1500 to 1700 on a single is better for a 3rd gen owner. Either way if you have that MLS gasket and studs you probably won't have any problems running a single or towing twins.

 

[SRadke]

If you're looking for big power (600+) combined with the ability to tow heavy, especially at high altituded twins are the only way to go. On a third gen you have a chance with a single because you can make big power on small injectors but if you're trying to do it on 200 hp injectors it just doesn't work.



I tried the S300 variant and liked it. It didn't cool well enough for me but everything else about it I liked. I took that turbo, another $1600 and bought everything I needed to put another turbo under it. I didn't go cheap either, $1300 and some for the big charger, wastegate, and manifold. The rest being silicone hoses, piping, oil lines and clamps. Had I been looking for the cheap route I could have used the stock charger on top and got the whole project done for $1000.



I'm never going back to a single. With my box off I get a max egt of 950° pre turbo at 31 psi boost



-Scott

 

[BDR]

Thanks for the replies fellas! Well if I could build my own, I would. But tools, welders, and knowledge are the things I lack in the field of "do it yourself" fabricating. I don't tow with my truck, maybe my motorcyle or some stuff in the bed. But that's it. I was actually looking at some Piers twins. I would love to install some twins with some help, that would save some money. I've got my transmission on the way, so I'm trying to figure where I want to go for a set up. Just lookin to have a sweet street truck. I just payed it off last week, so it's time to play.



Maybe:

Piers street twins

Mach ? injectors

O-ringed or fire ringed

studs

new gasket

 

[SRadke]

Mach 4's will make 500 hp with the right box and a single. If you're thinking twins mach 6's are sweet. My best advice is decide how far yuo want to go and work for it. Buying 2 clutches, 3 sets of injectors, and 2 turbos on your way is a spendy way to go about it.



-Scott

 

[BDR]

Did you fab up that external wastegate bracket, between the housing and turbo?

 

[OWeigel]

Twins theory?

I think there´s many of us that have a lot of wonders about twins and to how you set it up (or at least I do).

Anyone know about some old threads or links with that kind of info, like configs, routing, plumbing etc? (or if someone wants to educate us with a new thread?)

Dont want to hijack this thread, but i think this can be interesting for us who leaning towards twins.

 

[BDR]

That's why I started this thread, to learn more about twins.

 

[SRadke]

Yes, I built the wastegate space as well as all of the stuff in my setup. I bought exhaust elbows and cut/fit the radius' in the corners. I cut the flanges out of plate and turned the v-band flanges on the lathe. You don't have to go that far... . v-band and turbo flanges are available for sale if you don't have the machines to do it.



The best I can do for plumbing is to say look at my pics and try to get an idea of what is going where. If you have specific questions post, we'll try to answer.



-Scott

 

[RMalone]

Now this is an informative thread! Thanks guys.



I have a sps66 on my truck per sig. I'm not running pressure but from a 25mph roll my truck is a "fat old dog that just ate too much yardbird". Seriously I wouldn't race a stock civic from 25 to 50mph. When it finally boosts to about 14or15 psi it then goes to 45psi right now. But there is a 3-4 second wait for anything to happen.



So twins wont help with that kind of situation? I would love to use the sps66 in a twins arrangement.



Is it feasable to fab a set of "mini-twins" where you have a real small top turbo and a 66 class bottom? Would such a setup provide very fast spool and still support 50-55 psi or am I just dreaming? I would love to have a useable 450-500hp, but still get stock turbo type spooling.



My truck with the TST and stock turbo would smoke my truck with the sps66 and same setup if the race was from 25 or 30mph up to 60 or 70mph. Now from a dead stop when you can boost launch the sps66 would eat the stocker alive.



My point is if twins won't help with spool (realative to a big single) on a truck that spends most of it's time as a daily driver why bother? Unless your at the track or towing heavy what is the advantage? Still, they look Sooo COOL.

 

[TReed]

When you guys are talking about more maint. on a set of twins what are you referring to, name a few.



Travis

 

[swankmetal]

more clamps to come unglued, more oil fittings to squirt black goo, a LOT more bolts to retorque. more boost= more strain on everything, so i i like to keep it all a little closer to spec.

 

[BDR]

Is there a certain boost psi that twins are the most efficient? I would imagine it depends on the twin set up.