joez71

I'm new to the whole turbo scene but I'm totally hooked from all the success stories I've read. I have a 41k miles Gen IV Flexfuel 5.3 (LMG) sitting on the engine stand and I'm itching to get things put together Here's some info on the car I have:

• 71 Chevelle SS (setup for a BBC)
• Stock weight
• Fuel system completely removed - shooting for E85 as its plentiful here.
• TH400 with a 3000 stall TCI converter with anti-ballooning plate
• 3.73 gears (probably switching to something else once the turbo(s) is in)
• Minitub with 335 drag radials (stock size 12 bolt)
• All steel except for the fiberglass front bumper which will probably end up steel again soon... Not safe on the street.
• 6 point cage
• Expecting 95% street time and maybe 3-4 trips to the track each summer.

Maybe you can debunk some of my "assumptions" and sway me to single because I don't want to waste money and time.

Things I "think" I like about twins:

1. Twins will spool up faster and since this is a street car I want to be able to hit the gas and not have lag that I might with a bigger single.
2. Hot side piping will be easier to fabricate as nothing is crossing over.
3. The merge will be simpler as both sides will enter the intercooler and it will take care of the merge as it will have a single output.
4. Smaller diameter downpipe - Easier to route on each side
5. Simpler connection to dual exhaust system.
6. The twins will look better. Everything is symmetrical under the hood.

Things I "think" I like about single:
1. One turbo to configure so less room for error or something not matching the other side. (waste gate / boost control mostly).
2. Cost will be less. (I am going the eBay turbo route so it won't cost that much either way really).

I see sooooooooo many singles and so few twins theres got to be a big reason for it. If anyone can help me better decide I'd be really grateful.

Thanks!
Joe

8flat

In for answers, I've had these same questions myself. I'm building a '33 5 window coupe and really lean towards twins just for the symmetry aspect. Hadn't thought about faster-spooling though, that's a good point assuming it's typically true.

TyCZ28

Theres no reason not to do twins other than the price. You need 2 turbos 2 oil train and feed lines 2 wastegates etc. Also some dont have space for all of that extras.

joez71

All of my reasons above seem valid?

transam69230

iTrader: (49)

Spool is going to depend on the size of CI and size of twins you go with. Having twins doens't mean you loose all lag. For instance my 427 with twin 75/75s doesn't see positive KPA until 3650 rpm or so.

Twins are nice because you don't have make a merge/crossover pipe for the hotside, but you do for the cold side or run some sort of dual inlet intercooler single out.

joez71

I've seen a lot of single recipes out there for stock 5.3 + turbo cam, but very few for twin turbos. What twins would work well and push the car into the 10's and still be a blast on the street with relatively low RPMs?

I've been looking at these on eBay.... Let me know if you think any of these would be good/bad/etc...

TX-60-62 Turbo Charger 70 a/r 3" V Band Exhaust 62mm T4 Twin Scroll
http://www.ebay.com/itm/TX-60-62-Tur...ZU2qKE&vxp=mtr

TX-60-62 Turbo Charger 84 a/r 3" V Band Exhaust 62MM T4 Twin Scroll
http://www.ebay.com/itm/TX-60-62-Tur...9U2qJ~&vxp=mtr

If you know of any other ebay turbos that would fit let me know.

mkvamso

iTrader: (2)

I used twin cxracing gt35s on a 5.3 in my gto
It would see positive pressure around 2700rpm and would be at full song a few hundred rpm later
Made 730hp at 17psi and trapped 140 in a full weight gto

vinceI

iTrader: (5)

Unless you trying to fit a class that doesn't allow twins go for it. I built twins so I wouldn't chase some kind of heads up class.

joez71

I've spent a couple hours looking around and I keep finding amazing single turbo builds out there. All the parts listed... no guessing. I can't find anything that specific for twins. I'm really starting to second guess the twin thing... Singles are so much more popular and people are going 9's with them easy... and driving on the street plenty. I'm having a hard time finding a lot of info on twins and even more difficult twins with e85 (finding injectors and such)...

transam69230

iTrader: (49)

Here is my Twin build thread : https://ls1tech.com/forums/forced-in...whp-build.html

Here is my buddies Twin build thread : https://ls1tech.com/forums/forced-in...dominator.html

Here is another buddies single build thread switched to twins after awhile thread :

https://ls1tech.com/forums/forced-in...-56-161-a.html

Fuel injectors have nothing to do with a twin setup or single setup. Injectors are determined by fuel type and power goals.

Parts list for twins :

- Two turbos
- Two wastegates
- Intercooler (a2a or a2w)
- BOV ( 1 is fine , 2 if got money)
- Manifolds
- t4 flanges to mate turbos to up-pipes
- Hot side pipes
- Cold side pipes and associated couplers

joez71

The injectors have me a little concerned... A friend of mine has a similiar setup to what I'm building and hes completely maxing out his 80 lb/hr injectors. I'm sure this is an E85 issue as those injectors work great in the 600 whp range on 93 cars. If I go higher than 80 it looks like they are at least twice as much if not more.

There are a lot of "nearly stock" builds for singles and only a few "nearly stock" builds for twins. Are twins meant mostly for those who want just all out insane power as opposed to the rest of the world where a single seems to work fine? hahaha - Let me know. Thanks!

transam69230

iTrader: (49)

I would just ask you friend for advice sounds like he knows what is going on.

mkvamso

iTrader: (2)

I have a build thread on here as well, tried to answer as many questions as i could and take pictures along the way
Theres nothing terribly difficult about doing a twin turbo setup, there are more than enough resources on this site alone to help you get it done

The hardest part for me was making it look neat, you start running out of room for things like catch cans, overflow tanks, etc fairly quickly

toytech93

iTrader: (2)

This statement is very true, you run out of room very quick!

I have a build thread here as well, needs to be updated though. Progress has slowed down, getting married next week

6.0L, LS3 heads, twin 6165s, Holley EFI, 4L80E, 12 bolt

joez71

I certainly want things to look neat... Maybe a single is the way to go. I dunno. So many options. Oh, and I talked to my buddy and he said get the 80lb or 95lb injectors. I really wish there was a kit for this car.

Boo"SS"t

iTrader: (2)

Lasershop

iTrader: (2)

Yup... Two of everything. This could be you!

BOOSTAT4500

iTrader: (17)

I went with twins for most of the reasons you stated. Mainly, the ability to run smaller exhaust. I wanted a full exhaust out the back of the car. I don't think it's cluttered at all and works great.

Ratical

iTrader: (82)

Some people only hear what they want to. Lol

zrultima

The thing I have a question on a lot of turbo builds is why they use such large turbos?? Im coming from a diesel perspective I have a compound setup where I have a small 63mm turbo feeding into an 80mm turbo I can get it to spool up at 1800 rpm and after that it just flies to 60psi. I have learn boost is a restriction not necessarily power correct me if i am wrong but I would run something smaller like to 66mm