Twin turbo: 318 or 360, and why? This are your only options. GO!

Twin Turbo

  • 318

    Votes: 9 40.9%

  • 360

    Votes: 13 59.1%
  • Total voters
    22
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Build them how you want, stroker, screamer, let us know.
 
Why twins? Why not a single? EITHER "run whachaya brung"

WHY NOT A 273?
 
NOTHING beats Cubic Inches. Cubic inches + boost = Cubic inches on crack! Go big or go home!
 
If your building from scratch, the 360
If your using existing engines and only adding the snails, then the 318
Unless the 360 is a real low compression engine to begin with
 
Yes I have a 318 sitting in my shop cost me a case of good old Canadian beer ! Now some junk yard turbo’s and Bob’s your uncle ! Zoom zoom :thumbsup:
 
451Cuda said:
Either one will be fun and fast, but the extra stroke of the 360 will do a better job of getting the car moving before boost comes on.
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Keep the compression higher to get it moving and lower boost = the same on the top.
 
BigBlockMopar said:
So you provide us a box and we have to think inside it?
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Heresy!

See post #9.. keep true SCR in the low-mid 8's; it will indeed help this move out better before the turbo's spool up. (Direct experience of 7.4 vs 8.2 SCR in a turbo 4 banger that needed decent low-mid range torque.)

Sounds like the 318 vs. 360 choice is more about having a free 318. The 360 choice seems like a no-brainer....

So, OP, is this 1 turbo on each bank with an equalizer, or 2 turbos in series? We can't answer the question without this..... :D
 
The base motor is the only stricture. How you build it is up to you
 
teen it. you already got it and it will be a good learning experience. Take the entire top end off and put it on a 360 later if you feel like it. 302's make huge power on turbos with a small stroke. turbos allow you to make changes with little mechanical change to the base hardware.
 
69wacuda said:
The base motor is the only stricture. How you build it is up to you
Click to expand...
Oh well then I'll tell you my dream;
A staged kit with a big remote.
Two tiny ones, not twins; one stuck in up in each fenderwell with the exits coupled to valved bypasses, that then spool up the remote. The cold side plumbed to the primaries of a spreadbore, with small tubes. The remote coldside plumbed to cover the entire airhorn with a pressure balance to the primaries.
The front turbos are sized to work right off idle and be done sometime after cruising speed, say 2800.
The remote is sized to be ready to begin about there and power up the topend.
Who cares what size SBM you use with this set-up, the fronts are already making 360HO torque, rpm for rpm. I'd probably start with a cheap to replace heavy-rod 318 with a steel crank. I'd try to hide the cold pipes in the cowl and pressurize a modified 14" OEM type air filter house. You'll have to look carefully to find the turbos.
If I had to, I would sacrifice the rear seat, cuz nobody has been there in ~16 years. The seat has not even been in the car since 2004.
I would try to run it with no mufflers.
I would switch to an automatic. And start with 2.94 gears, for 65~2300rpm. That means I would have to run the standard 727 ratios to hit 60=5450.... still in first gear. And that means an easy-on-the-fuel cam, and a remote dial-a-pressure;maybe.
I'd try it with about a 2200stall.
I hate BOVs

Although I do have a 273 block, and a steel 318 crank,hmmmmmmmmmmm;
oh sorry 273 was not on the list,lol.
I didn't vote yet
Ok then;I could make it small-valve 360 heads, onto a 318,with maybe a 360 cam, I think I got a couple of those around here somewhere........

I'd be happy with about 440/350, cuz a fun streeter don't need a lot of horsepower, but with a stinking automatic, it does need a wide torque band, that starts right at stall.
 
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AJ/FormS said:
Oh well then I'll tell you my dream;
A staged kit with a big remote.
Two tiny ones, not twins; one stuck in up in each fenderwell with the exits coupled to valved bypasses, that then spool up the remote. The cold side plumbed to the primaries of a spreadbore, with small tubes. The remote coldside plumbed to cover the entire airhorn with a pressure balance to the primaries.
The front turbos are sized to work right off idle and be done sometime after cruising speed, say 2800.
The remote is sized to be ready to begin about there and power up the topend.
Who cares what size SBM you use with this set-up, the fronts are already making 360HO torque, rpm for rpm. I'd probably start with a cheap to replace heavy-rod 318 with a steel crank. I'd try to hide the cold pipes in the cowl and pressurize a modified 14" OEM type air filter house. You'll have to look carefully to find the turbos.
If I had to, I would sacrifice the rear seat, cuz nobody has been there in ~16 years. The seat has not even been in the car since 2004.
I would try to run it with no mufflers.
I would switch to an automatic. And start with 2.94 gears, for 65~2300rpm. That means I would have to run the standard 727 ratios to hit 60=5450.... still in first gear. And that means an easy-on-the-fuel cam, and a remote dial-a-pressure;maybe.
I'd try it with about a 2200stall.
I hate BOVs

Although I do have a 273 block, and a steel 318 crank,hmmmmmmmmmmm;
oh sorry 273 was not on the list,lol.
I didn't vote yet
Ok then;I could make it small-valve 360 heads, onto a 318,with maybe a 360 cam, I think I got a couple of those around here somewhere........

I'd be happy with about 440/350, cuz a fun streeter don't need a lot of horsepower, but with a stinking automatic, it does need a wide torque band, that starts right at stall.
Click to expand...


You forgot the NOS, put the NOS nozzle in the turbo housing aimed at the fan to spool up the turbo faster, Now were having fun:lol:
 
OK, I vote for 2 turbo's, one on each exhaust. No need for 2 in series as that is just to get to higher levels of boost. Easy to get 15 psi with this size of engine and some common turbo's.

Mitsubishi 14G's will get 12-15 psi boost easily for 2.6L displacement..... more than you are gonna be able to use without getting better pistons, forged crank, etc. (Block will be pressed with 15 psi.... it'll be pushing past 500 HP if you intercool it!) The 14G Mitsubishi is easy to find, plenty of sources, and plenty of improved models for more boost and better low end spooling. 16GSuper with a better impeller would be impressive. Use the wastegates for sure. Will need some attention to keep things boosted evenly side-to-side and get the 2 wastegate responses equal; maybe there is some control to make that better. Surely that has all been done.

I'd for sure go want to go with an electronic FI for this; TBI would be adequate IMHO. But it will take some fanagling and patient tuning to make this work unless you can find some already made maps.

Not a project for the faint of heart....
 
If it is truly my call you can toss those snails on a neon, and put a 6-71 On the 360
 
one of a series of GM 2 stroke helical rotor positive displacement superchargers from 2/71 up
71 is cubic inches of each cylinder 53 and 110 are also popular
dragsters run 14/71s
google 6 71 supercharger
put one under that scoop
 
doogievlg said:
What are your goals?
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Daily (3 season) driver/WEEKEND WARRIOR! .
Quick spooling, Mild/moderate boost (8-12psi)
Reliability, not looking for peak power output; yet, but maybe a dedicated racer in the future. Just laying the ground work.

Honestly just need a strong base engine that can handle the boost.

Currently, the car has a 71 360 with 120psi in most cylinders. Less than 10%deviation between all cylinders. Motor was built about 23years ago, but sat off and on for 15 of those years. Probably only has 4k miles on the motor. I will probably go with a stroker kit since I'm rebuilding anyway, but we'll see.

I thought a 392 stroker 318 would be pretty sick as well.

I was wondering if an original 4 barrel 318 would be a better rotating assembly than a stock 71 360.
 
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