Compound turbo, thoughts?

mechanicboy · Apr 19, 2016

Ok, Introduction first.

I have a complete 2016 2.3 ecoboost/auto combo pulled to transplant into my 1972 Mercury Comet. It was too good of a deal to pass up. I was originally going to convert to a mustang II front suspension and Coyote but this will save me about $5k and save a bunch of time so I figured what the heck, I'll give this a go. I'm probably the first to attempt this, but I don't mind a challenge.

Now to the real question here. I have been watching several forums and several builds and I've always wondered why no one has even mentioned doing a compound turbo build. Is it just costs? More space requirements(won't be as big an issue for me)? Is there something wrong with the stock turbo to make this not a good idea?

I ask because I love what I've seen the stock turbo do for low end torque development. I also want the car to do 10s, preferably mid 10s so I'm thinking around 500rwhp range. Keep in mind the Comet will likely weight less than 3k lbs with me in it (I'm actually thing more like 27-2800lbs because the weight savings of the 2.3 vs v8).

If your only opinion is to be negative without backing up your statement, then please keep that opinion to yourself. Constructive criticism is ok.

Thanks.

Edit: Some more background. I have a 2012 Supercharged supercrew 4wd Coyote(goes 11s), I love the torque. The stock turbo provides great low end torque with good spool time, I don't want to lose this. I know I'm not going to get that instant torque. I've had turbo diesels and current still own a turbo volvo that's had the turbo swapped and I miss the low end the stock turbo gave. I don't want to make that mistake again.

Jewishthunder · Apr 19, 2016

A - if you're in NorCal near the bay, I want to see it when it's done.
B - compound setups are always a nightmare to fine tune. Also, for 500whp the cost doesn't make as much sense. Turbo tech has come so far it's not as needed unless you're trying to spin up a MASSIVE turbo.

mechanicboy · Apr 19, 2016

Jewishthunder said:
A - if you're in NorCal near the bay, I want to see it when it's done.
B - compound setups are always a nightmare to fine tune. Also, for 500whp the cost doesn't make as much sense. Turbo tech has come so far it's not as needed unless you're trying to spin up a MASSIVE turbo.

A. I'm in the Valley, 90 miles north of Sac
B. The dyno graphs I've seen of the larger turbos to get to the power range I want to be look like they leave too much to be desired below 4k rpm.

While I definitely will be drag racing this car, it must be very derivable, I want to be able to drive it up to Hot August nights in Reno without have to rev the engine up to climb the hills.

I'll add some more background to my original post to help you understand where I'm coming from.

Lastly, I have thought about A Nitrous/e85 secondary system do get there, but I'd spend more for the turbo setup if for no other reason that being unique.

EcoBoostin · Apr 19, 2016

mechanicboy said:
A. I'm in the Valley, 90 miles north of Sac
B. The dyno graphs I've seen of the larger turbos to get to the power range I want to be look like they leave too much to be desired below 4k rpm.

While I definitely will be drag racing this car, it must be very derivable, I want to be able to drive it up to Hot August nights in Reno without have to rev the engine up to climb the hills.

I'll add some more background to my original post to help you understand where I'm coming from.

Lastly, I have thought about A Nitrous/e85 secondary system do get there, but I'd spend more for the turbo setup if for no other reason that being unique.

Chico?

Glenn G · Apr 19, 2016

Seems like a good idea, i'd love to see it when it was done.
The main reasons why it hasn't been done before.

1)Cost benefit ratio. As mentioned before Slightly larger modern turbos will give you 500 whp capability while losing only a bit of low end so the cost of building a tuning a compound system will out weigh the benfit for most people.
2) Motor Reliability: The instant hard hitting torque of the OEM turbo cvan and does break this motor if abused. 420ish ftlbs at 2500 RPM is a massive strain on the conrods of a 4 cylinder. I think 400-450 WHP is considered the 'safe' limit on the stock block. The stock turbo will make a good 320ish at the wheels so the bigger turbo cannot be that much bigger negating some of the advantage of going compound.
3)Fueling: The stock Fueling system is pretty much done at 400ish whp as well. you would need some sort of aux fueling to make it worthwhile.

If you go to a built block ~$3k some sort of Aux fuel system ~$1k Cost of the bigger turbo ~$1-2 k and all the custom work to get it fit, it would be a beast. Remember you still need an Intake, intercooler downpipe and exhaust.

But you can see why for most people it's easier to just pay ~$3K for a full bolt on kit, have their 400 whp with the capability to go to 6 if they do decide to build the engine.

All that being said, If you can pull it off, I'd be looking forward to lots of pics and dynosheets, true car-porn stuff there. It would be a work of art and like most art, making financial sense is not really the point.

04SloSnake · Apr 19, 2016

There was a shop on here that was talking about it a few months ago, but for the life of me I cannot remember what company. I remember it was kind of their thing though.

dragonacc · Apr 19, 2016

ATM was talking about it, but nothing has come of it so far. Not sure if [MENTION=11871]JerseyDevil[/MENTION] has any new developments.

higdominator · Apr 19, 2016

Assuming you have all of the electronics to run the swap....

A compound build is more flair that functional IMO. The time spent getting it right and tuning it would be much greater than doing a proven build.

An EFR 7163 would be ideal. Quick spool, plenty of power up top to get you where you need to be. Other wise the PTE5558 is another smaller big turbo option to get you where you need to be.

But what about all that lag? Easy answer- Circle D torque converter. I added a 4K stall to my 5558 and the car went from sluggish pile of expensive parts to wicked beast. Off the line it would previously require a difficult to obtain foot brake stall or just patience as boost built. Now I can be sitting at a light and just mash the gas, the converter flashes, and the tire roast begins (at least on cold DR's on the street).

I don't mean to discourage making something really cool, but realistically a sequential setup just doesn't seem to be necessary with the availability of twin scroll turbos and other supporting mods.

*edit: the time in my sig was ran with a stock converter dealing with all that "lag" ;) That MPH is 10 second territory in a car that weighs 3610lbs....

arghx7 · Apr 19, 2016

Fuel system point is a good one. If a bolt on turbo will max out the fuel system, and no aftermarket higher flow parts for the high pressure side are available, why go with a complicated turbo system?

Jewishthunder · Apr 19, 2016

The idea of running a low HP nitrous shot (50-75) with a larger turbo makes a lot more sense to me. Obviously this needs to be a built block or you will shit it's guts.

This would bring you the torque band you want for drags early on, and help with turbo spool. Now, I think if it's been a hot minute since you've had a new big turbo car you might just want to look at the newer turbos with newer billet wheels. You can make plenty of power under 4k rpms, and then really have it come on after that.

The new Borg Warner turbos are things of beauty as usual from BW, and the GTX wheels of new garrett turbos are never a bad idea.

mechanicboy · Apr 19, 2016

EcoBoostin said:
Chico?

Pretty close.

Glenn G said:
Seems like a good idea, i'd love to see it when it was done.
The main reasons why it hasn't been done before.

1)Cost benefit ratio. As mentioned before Slightly larger modern turbos will give you 500 whp capability while losing only a bit of low end so the cost of building a tuning a compound system will out weigh the benfit for most people.
2) Motor Reliability: The instant hard hitting torque of the OEM turbo cvan and does break this motor if abused. 420ish ftlbs at 2500 RPM is a massive strain on the conrods of a 4 cylinder. I think 400-450 WHP is considered the 'safe' limit on the stock block. The stock turbo will make a good 320ish at the wheels so the bigger turbo cannot be that much bigger negating some of the advantage of going compound.
3)Fueling: The stock Fueling system is pretty much done at 400ish whp as well. you would need some sort of aux fueling to make it worthwhile.

If you go to a built block ~$3k some sort of Aux fuel system ~$1k Cost of the bigger turbo ~$1-2 k and all the custom work to get it fit, it would be a beast. Remember you still need an Intake, intercooler downpipe and exhaust.

But you can see why for most people it's easier to just pay ~$3K for a full bolt on kit, have their 400 whp with the capability to go to 6 if they do decide to build the engine.

All that being said, If you can pull it off, I'd be looking forward to lots of pics and dynosheets, true car-porn stuff there. It would be a work of art and like most art, making financial sense is not really the point.

1. Losing enough torque to need a converter, no?

2. How many people have popped the rods on a stock turbo?

3. I've read there's aftermarket injectors, how good are those and how much do they cost? I'm already building a custom fuel system...

Short block could happen, but after everything else is built. As for tuning, that will be an adventure in itself because I'll be doing my own tuning. I fact, I'll be doing almost of of this myself. Custom intake, intercooler/piping, exhaust and fuel system will be needed just to fit the engine in the car. I'll have the major supporting mods done before the car drives an inch.

higdominator · Apr 19, 2016

mechanicboy said:
Pretty close.

1. Losing enough torque to need a converter, no?

2. How many people have popped the rods on a stock turbo?

3. I've read there's aftermarket injectors, how good are those and how much do they cost? I'm already building a custom fuel system...

Short block could happen, but after everything else is built. As for tuning, that will be an adventure in itself because I'll be doing my own tuning. I fact, I'll be doing almost of of this myself. Custom intake, intercooler/piping, exhaust and fuel system will be needed just to fit the engine in the car. I'll have the major supporting mods done before the car drives an inch.

1. It's not lost, just moved a bit;) And yes, a converter is ideal.

2. About 90% or more of the blown motors have been on stock turbos.

3. Injectors aren't the problem, it's the HPFP. It will not flow enough to support big power without Aux injection.

How to you plan to control the motor? ECU? Did you pull the entire PCM from the donor, with gas pedal?

Glenn G · Apr 19, 2016

mechanicboy said:
Pretty close.

1. Losing enough torque to need a converter, no?

2. How many people have popped the rods on a stock turbo?

3. I've read there's aftermarket injectors, how good are those and how much do they cost? I'm already building a custom fuel system...

Short block could happen, but after everything else is built. As for tuning, that will be an adventure in itself because I'll be doing my own tuning. I fact, I'll be doing almost of of this myself. Custom intake, intercooler/piping, exhaust and fuel system will be needed just to fit the engine in the car. I'll have the major supporting mods done before the car drives an inch.

1) I know jack about automatics, so someone more knowledgeable than me will have to answer that one.

2) a few, but mostly on the stock turbo and some of the "Driving Mrs Daisy" accounts of how it happend are suspect.

3) it's not really the injectors, it's the HPFP that cant keep up, Larger injectors without a HPFP upgrade (which AFAIK, isn't available yet) won't do much.

Tune+ · Apr 19, 2016

mechanicboy said:
Ok, Introduction first.

I have a complete 2016 2.3 ecoboost/auto combo pulled to transplant into my 1972 Mercury Comet. It was too good of a deal to pass up. I was originally going to convert to a mustang II front suspension and Coyote but this will save me about $5k and save a bunch of time so I figured what the heck, I'll give this a go. I'm probably the first to attempt this, but I don't mind a challenge.

Now to the real question here. I have been watching several forums and several builds and I've always wondered why no one has even mentioned doing a compound turbo build. Is it just costs? More space requirements(won't be as big an issue for me)? Is there something wrong with the stock turbo to make this not a good idea?

I ask because I love what I've seen the stock turbo do for low end torque development. I also want the car to do 10s, preferably mid 10s so I'm thinking around 500rwhp range. Keep in mind the Comet will likely weight less than 3k lbs with me in it (I'm actually thing more like 27-2800lbs because the weight savings of the 2.3 vs v8).

If your only opinion is to be negative without backing up your statement, then please keep that opinion to yourself. Constructive criticism is ok.

Thanks.

Edit: Some more background. I have a 2012 Supercharged supercrew 4wd Coyote(goes 11s), I love the torque. The stock turbo provides great low end torque with good spool time, I don't want to lose this. I know I'm not going to get that instant torque. I've had turbo diesels and current still own a turbo volvo that's had the turbo swapped and I miss the low end the stock turbo gave. I don't want to make that mistake again.

ATM is doing a compound turbo setup that I will be tuning here shortly. I actually just tuned a supercharged and turbocharged Ecoboost the other day. Great results but a little too much boost down low for my taste but they understood the repercussions of such spool.

You can do it, but without a built motor you really aren't going to get the benefit that compound turbo setups generate.

Tune+ · Apr 19, 2016

mechanicboy said:
A. I'm in the Valley, 90 miles north of Sac
B. The dyno graphs I've seen of the larger turbos to get to the power range I want to be look like they leave too much to be desired below 4k rpm.

While I definitely will be drag racing this car, it must be very derivable, I want to be able to drive it up to Hot August nights in Reno without have to rev the engine up to climb the hills.

I'll add some more background to my original post to help you understand where I'm coming from.

Lastly, I have thought about A Nitrous/e85 secondary system do get there, but I'd spend more for the turbo setup if for no other reason that being unique.

Maybe you just seen the wrong graphs? I make 30psi by 2900rpms and make 500whp, that is more than enough for a small displacement big turbo car.

Compound turbo, thoughts?

mechanicboy

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Jewishthunder

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mechanicboy

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EcoBoostin

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higdominator

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arghx7

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Jewishthunder

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mechanicboy

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higdominator

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Glenn G

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Tune+

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Tune+

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