Twins vs single?

03dsgdreams · Aug 28, 2013

What are some of the benefits if any of a twin turbo kit over a single turbo kit? Lets say Helliions twin 62s vs JPC's single 76 for comparison. Is there a big difference in how the power comes on between the kits, which has the least lag? On lets say 7 pounds of boost on a stock coyote for each kit which one would make the most power/torque?

UnleashedBeast · Aug 29, 2013

My opinion,

Twins offer smaller turbos that can spool faster, offering a higher power potential from built engines. The piping is also better laid out with twins, compared to single. I've seen single piping on the S197. It's looks like poo to me.

CSG · Aug 29, 2013

I assume you meant the JPC single?

Single Vs. twin has been a hot debate for as long as I can remember. Plenty of opposing opinions with very few legitimate "facts". It is said a lot that the twins will spool faster since they are smaller turbos, but they are also only seeing half of the exhaust flow so i'm not convinced that that holds true to a noticeable extent. I'll be honest and say that I went twins simply because I think they are "cooler".

D.T.R · Aug 29, 2013

Usually, twins will spool up a little faster.
That's the main reason when you look at promod or cars in that level go twin and not single.

CPRsm · Aug 29, 2013

CSG is right. Twins can be smaller in size, but has half the energy to apply force on the turbo. Singles have more preturbine volume which lowers back pressure and can slow spool. Twins can be the opposite. The sooner u pressurize the hotside the sooner stuff spins. There is more to it than that generally. How kits are built are just as important. I prefer a big single. In this chassis you can fit a 5in down pipe which is larger in volume than twin 3in down pipes. This helps spool and relieves back pressure as well.
Post turbo volume is a big one as well. Longer it takes, the longer time to torque. For twin or single. Single will generally win here. Intercooler size is a determining factor. Use a small cooler and spool faster. If it's too small, the power starts to drop the longer you're on it because of rising inlets. We've been able to spool faster than any twin on the market by a few hundred rpm. and even faster yet with an air to water intercooler. So it being twins is not an automatic win there.
Twins do not also automatically mean more power. Power comes from efficiency. Where your plot is on a compressor map, if the AR housing is sized right, can the turbine process enough exhuast? Long story short it comes down to more than one or two turbo lol

D.T.R · Aug 29, 2013

CPRsm said:
CSG is right. Twins can be smaller in size, but has half the energy to apply force on the turbo. Singles have more preturbine volume which lowers back pressure and can slow spool. Twins can be the opposite. The sooner u pressurize the hotside the sooner stuff spins. There is more to it than that generally. How kits are built are just as important. I prefer a big single. In this chassis you can fit a 5in down pipe which is larger in volume than twin 3in down pipes. This helps spool and relieves back pressure as well.
Post turbo volume is a big one as well. Longer it takes, the longer time to torque. For twin or single. Single will generally win here. Intercooler size is a determining factor. Use a small cooler and spool faster. If it's too small, the power starts to drop the longer you're on it because of rising inlets. We've been able to spool faster than any twin on the market by a few hundred rpm. and even faster yet with an air to water intercooler. So it being twins is not an automatic win there.
Twins do not also automatically mean more power. Power comes from efficiency. Where your plot is on a compressor map, if the AR housing is sized right, can the turbine process enough exhuast? Long story short it comes down to more than one or two turbo lol

Which turbo did you use in your test that shows you spool faster than twins? And what WHP can you make with that turbo ?
A lot of these twin kits for the 5.0 have a LOT of room to go. IIRC, hellion made over 1250whp with more room to go... I want to say that in order to make that kind of numbers on a single on this motor you would probably need an 80mm if not bigger... that would be a more fair comparison of spooling IMO.

Deespeed99 · Aug 29, 2013

Single...im a little biased though LOL!

stretchb · Aug 29, 2013

twin Paxtons

CPRsm · Aug 29, 2013

D.T.R said:
Which turbo did you use in your test that shows you spool faster than twins? And what WHP can you make with that turbo ?
A lot of these twin kits for the 5.0 have a LOT of room to go. IIRC, hellion made over 1250whp with more room to go... I want to say that in order to make that kind of numbers on a single on this motor you would probably need an 80mm if not bigger... that would be a more fair comparison of spooling IMO.

To be fair hellion didn't make 1250rwhp. And I don't think their intercooler will support that. It was more like 1050rwhp uncorrected. And a 76 will do that. The 80's in this frame have done just under 1300rwhp and 84's are coming out

We used a 74mm for that testing, and we took it past factory limits no problem. You may not think it's a fair comparison but that's the advantage. This frame has tons of options. The twin kits on the market can't change AR or turbine without fabwork. The T4 stuff is stuck at .68 because the widths are different. T3 va and only has two sizes, neither have turbine selections. So being able to go smaller in the same frame has its advantages. A smaller set of twins can spool sooner as well, but will it fit the turbo kit? It's not to say one is better than the other, that wasn't really the point. Ea is different, but differences usually lay more in kit design than one or two turbos.

RUQWKNF · Aug 29, 2013

D.T.R said:
Usually, twins will spool up a little faster.
That's the main reason when you look at promod or cars in that level go twin and not single.

Just to set the record straight, turbo Promod cars run twins because they are trying to make over 4000 hp in order to be competitive in the class. No single turbo has ever come close to supporting that hp level, as the T5/T6 frame size / component level limitations, are far surpassed for that power level. I should know as I worked for PTE when twin turbos were first introduced in NHRA Promod racing. Not meaning to pick on you D.T.R., just stating facts.

Some very good points have been made. Here are a few that I can think of off the top of my head.

 Pro’s for single turbo:

Less plumbing required with both piping and oil feed/return lines.
When properly spec’d, a single can spool up just as fast as twins.
Less chance of boost leaks in the piping.
Auxiliary component requirements and pricing are typically less.
Capability for cooler charge temps with an air to air intercooler, where a single can utilize the entire core, vs twins utilizing a split core.
Less underhood heat associated with a single.
It’s also easier to manage the heat generated in a certain area, vs having to relocate and or blanket electrical or fluid containing components.
Typically lower costs associated with repair and or refreshing the turbo when it comes time. (IE: age and or amount of mileage and or track passes the turbo has on it)

Con's for single turbo:

You are ultimately limited to the amount of hp potential with a single T4 frame size turbo. Typically around 1300 fwhp is it with a standard T4 frame size turbo. Anymore would require completely reconfiguring the kit to accommodate a T5/T6 large frame turbo. Underhood room, plays a huge factor at those hp levels. We already have very little space to work with as it is.
Back pressure can become an issue when trying to make as much hp as a single unit can make. Just because a single is rated to support 1300 fwhp, you might not be able to make it because of back pressure issues.
Typically, blow off valve and wastegate requirements are higher/larger than what is required on a low boost twin setup.
A single is more susceptible to turbine wheel damage if something comes out of the engine due to failure. IE: Broken ring lands, broken piston rings, welding slag from the pre-turbo exhaust, spark plug tips. Anything that could come out of the engines exhaust that is not supposed to. You have a 50/50 chance of damage with twins in that scenario.
If not properly sized or spec'd, you could have significant lag associated with a large single.

Pro's for twin turbos:

Packaging and placement requirements are less, vs a medium/large frame single turbo.
You can get away with using smaller turbos for a given hp goal.
Boost levels are typically lower.
Spoolup characteristics or "Transient response" is typically faster with two smaller units. However this can be offset slightly by using a single turbo with a dual ball bearing CHRA. (Which I HIGHLY RECOMMEND on any turbo setup)
Twins work very well on a high intake/exhaust flow engine such as the Coyote. Especially with the v-band / v-band style turbine housings as used on Hellions kit. Whenever you can keep the exhaust flow to the turbine wheel on a round path, efficiency is high.
Ultimately more hp potential is available with twins, as you can simply crank up the boost and not run into back pressure issues.
Transient response between shifts is a lot faster for a given boost level. (only on manual trans equipped applications, automatic guys don't have to worry about this, as boost is maintained between shifts :rockon IE: boost recovers quicker after the shift. Mainly due to the smaller rotating assemblies used on the smaller twins.

Con's for twin turbos:

Plumbing and piping requirements are more. More clamps, more hoses, more pipes.
More potential for boost leaks and harder to diagnose boost leaks when they occur.
Finicky oil feed and return line setup, vs a much simpler single feed and single return on a single turbo setup.
Higher costs associated with repair and or refresh if something happens to the engine or turbos.
Higher underhood heat temps. Two turbine housings and two wastegates generate a lot of underhood heat. Typically requiring heat blankets and or relocating of electrical components or fluid containers.
More front end weight added to the car with twins vs a single.
Limitations with turbine housing selection for more flow, once you reach back pressure limits of the turbos used. IE: reconfiguring of the hot side piping would be required, if you were trying to make more power than the turbos can support.
The potential for more cooling system requirements, due to increased underhood temps and engine oil temps generated with twins.
Higher costs associate with more components in the kit.

These are just some of the points that come to mind between the two setups. I helped customers spec turbos for both single and twin applications on a daily basis, with thousands of different engine combinations. Both of the front running kits on the market today (JPC & Hellion) have been thoroughly tested and are high quality designs. I am a fan of both of their kits. I am not knocking the On3 setup in the least, (or anyone else's kit for that matter) as it too has it's place (price point) in the market. On that note, I will just say that I know the components used in both JPC and Hellions kits and I know of their quality and reliability. I worked with both companies on a daily basis while at PTE and can vouch for both of them with high respect. Both are excellent companies to work with and I would not hesitate to recommend either one of them. Great bunch of guys. I go with what I know when selecting my personal go fast parts. I myself prefer the simpler route, so JPC is the way I would go.

In summary, it really comes down to what your ultimate goals and preferences are for your car. Some people prefer the Shock and Awe factor of twins when the hood is popped at the local cruise in. Others prefer the simpler setup with a single turbo. When it comes to HP potential, both have their merits. Make 700 rwhp and never go higher? A properly spec'd single turbo will do that all day long without breaking a sweat. Make 1300 rwhp on kill without maxing out the turbos? Twins are your best bet. In the end, you won't regret going with a turbo setup, as it is the most efficient way to make power, although not the easiest to install nor the cheapest. And lastly, in my personal opinion, it is the most addictive power adder. There's nothing quiet like the rush of that full boost pull that never let's up when making a 1/4 mile pass. Combine that with the sound of a 747 airliner spooling up for take off. It's more addictive than the smell of fresh cooked bacon eggs and toast in the morning.
:rockon:

Hope some of this helps.

Patrick

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SteveG@Lethal · Aug 29, 2013

CPRsm said:
To be fair hellion didn't make 1250rwhp. And I don't think their intercooler will support that. It was more like 1050rwhp uncorrected. .

I am not going to start, argue or anything and will not down grade anything and I mean that!!

But Hellions car has the same system that everyone can buy and did make 1250 SAE in NM. Below is the attached graph. We did tune this car. Aluminator motor w/ valve spring & billet gear, Return style fuel system w/ race fuel, basic Twin turbo kit from Hellion, and a manual

And before someone says MPH isn't accurate. with dyno's running off a wheel sensor, the mph reading is the true info.

but here is the graph in RPM. You can see we even let off just over 6500. The number is only different by 15 and I can promise no one will feel that difference.

OP, you can be happy with either route. Just comes down to what you really want with the car.

CPRsm · Aug 29, 2013

Steve@BBR said:
I am not going to start, argue or anything and will not down grade anything and I mean that!!

Ok? Do you have the uncorrected graph that is 17-20% lower than the one you posted?

4.6+5.0 · Aug 29, 2013

I've got a dumb question, why no more than 2? Is it possible to do a 3 or 4 turbo setup? Just something I've always wondered even though 2 makes plenty power as well as 1.

Ultrakla$$ic · Aug 29, 2013

^^^:dw:

Nuar · Aug 29, 2013

4.6+5.0 said:
I've got a dumb question, why no more than 2? Is it possible to do a 3 or 4 turbo setup? Just something I've always wondered even though 2 makes plenty power as well as 1.

two on each side of the engine :rockon:

epper:

poof100 · Aug 29, 2013

D.T.R said:
Which turbo did you use in your test that shows you spool faster than twins? And what WHP can you make with that turbo ?
A lot of these twin kits for the 5.0 have a LOT of room to go. IIRC, hellion made over 1250whp with more room to go... I want to say that in order to make that kind of numbers on a single on this motor you would probably need an 80mm if not bigger... that would be a more fair comparison of spooling IMO.

The JPC race car made over 1250rwhp with a PTE 7685 Single.

Commenting in these types of threads is always tough, cause you have the Single camp and the Twins camp. Both make power and both will make you happy.

My JPC Single Turbo car runs pretty strong from the track mph on only 10-11psi and only that much power in 3rd and 4th gear.

Really comes down to what you prefer, who is doing the install and tuning, etc. I'm lucky to have JPC close by.

Sof Top · Aug 29, 2013

Nuar said:
two on each side of the engine :rockon:

epper:

fap fap fap fap

Stormtrooper5.0 · Aug 29, 2013

poof100 said:
The JPC race car made over 1250rwhp with a PTE 7685 Single.

"My JPC Single Turbo car runs pretty strong from the track mph on only 10-11psi and only that much power in 3rd and 4th gear."

What did you mean by this? I'm a bit confused, maybe I'm just dumb. Haha. But I'm very interested in what you meant.

poof100 · Aug 29, 2013

Stormtrooper5.0 said:
What did you mean by this? I'm a bit confused, maybe I'm just dumb. Haha. But I'm very interested in what you meant.

I am running the AMS 1000 boost controller that allows you to run Boost by Gear. Since my car is a stick, we run a different boost level for 1st, 2nd, 3rd and 4th gears. We ran 145mph on our best pass with the following boost levels in each gear:

1st- 6.5psi
2nd- 8psi
3rd- 10psi
4th- 10-11psi

Basically what I meant is that we went 145mph in the 1/4 with only running 10psi in 3rd and 4th gear and lower boost levels in 1st/2nd. Wanted to show how efficient the Single 76 setup is at low boost levels.

Stormtrooper5.0 · Aug 29, 2013

poof100 said:
I am running the AMS 1000 boost controller that allows you to run Boost by Gear. Since my car is a stick, we run a different boost level for 1st, 2nd, 3rd and 4th gears. We ran 145mph on our best pass with the following boost levels in each gear:

1st- 6.5psi
2nd- 8psi
3rd- 10psi
4th- 10-11psi

Basically what I meant is that we went 145mph in the 1/4 with only running 10psi in 3rd and 4th gear and lower boost levels in 1st/2nd. Wanted to show how efficient the Single 76 setup is at low boost levels.

Ahh I see! That's freaking awesome!! Thanks for the clarifications. Any videos of said car? Sounds like an amazing setup.

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