Twin Turbo Better On Engine Than Single?

[GNDreamin]

http://www.espperformance.com/twins.html

I was reading on this websight the other day and it mentioned this twin turbo setup for the Grand National engine. It claims to generate 500hp while maintaining lower temperature and 10lbs of boost pressure in the cylinder walls. I'm no turbo expert but I would think that 10lbs of boost from one turbo or two wouldn't make any difference to your engine. Wouldn't one turbo at 20lbs of boost be the same as two turbos at 10lbs of boost each...or does air work differently when calculating that? I know the twins would spool up faster but would their actually be such a drop in total boost pressure and still maintain the horsepower?...or are they refering to each turbo running at 10lbs? I'm not trying to make any accusations against the company I'm just trying to gain some understanding. Thanks for any help in clearing up this confusion for me :biggrin:

 

[Sinful6]

http://www.espperformance.com/twins.html

I was reading on this websight the other day and it mentioned this twin turbo setup for the Grand National engine. It claims to generate 500hp while maintaining lower temperature and 10lbs of boost pressure in the cylinder walls. I'm no turbo expert but I would think that 10lbs of boost from one turbo or two wouldn't make any difference to your engine. Wouldn't one turbo at 20lbs of boost be the same as two turbos at 10lbs of boost each...or does air work differently when calculating that? I know the twins would spool up faster but would their actually be such a drop in total boost pressure and still maintain the horsepower?...or are they refering to each turbo running at 10lbs? I'm not trying to make any accusations against the company I'm just trying to gain some understanding. Thanks for any help in clearing up this confusion for me :biggrin:

You're forgetting something very important that most people do when then learn about turbochargers. The difference between Flow and Pressure. A turbo at 10psi and (2) turbos at 10psi are NOT the same. (2) turbos at 10psi is NOT 20psi. The engine is still seeing 10psi of pressure, BUT, it is seeing twice as much AIRFLOW(measured in CFM) as with a single turbo. Thus the power benefit of more air. Coming from the Supra world, I can tell you that twins don't necessarily spool faster than a single. IMHO, I'd say single for a GN.

Hope this helps you out.

 

[ESP Products]

Hello, I re-read the page and didn't see any mention of "..10lbs of boost pressure in the cylinder walls." The only mention I saw of 10 lbs was "...At only 10 psi of boost you can still produce 500 hp (380 hp and 425 ft/lbs to the tires)." and "Turn the boost down to 10 pound and still know you have the power for mid 11s."

Feel free to ask any questions you want.

P.S. I've been in powerful single turbo Buicks and this Twin. I like the Twins much better. As far as Buicks, you can't tell me that this isn't faster spooling. The Supra had a totally different design. Again, I've been in both types of Buicks. IMO :biggrin: We have no lag; and the power comes on much lower/sooner.

 

[GNDreamin]

Thanks....I knew I was missing something.

 

[BlackBandit]

I don't get how 10 psi from two turbos is going to flow any more than 10 psi from one turbo if you're measuring intake pressure. Seems to me the intake is going to flow the same volume at 10 psi regardless of whether you use one turbo or fifty. I could be wrong though, after all I am just a simple man from Michigan.

 

[22lbChevelle]

I'm with this guy..

 

[Googs]

Psi or pressure is a measurement of resistance in the engine. Using 2 turbos at a given psi is similar to upgrading to bigger single turbo, the same resistance, just more volume. For example, lets say, on a given set up, a stock turbo flows 300cfm at 15psi then a PT70 would flow 600cfm at the same pressure. The bigger turbo is able to move more volume, same as the 2 turbos. I hope my crude explaination helps.

 

[BlackBandit]

Psi is a measure of resistance. Since the resistance of the engine is a constant the only thing we can do is change the characteristics of the flow of gasses (air) into the engine. USUALLY a bigger turbo it more efficiant than a smaller one (on our drivers) and therefore will move more air at a given psi. However, go too big and you'll start to lose power again, (mainly cause you can't spool the thing) just like if you take a stock turbo to 45 psi. It's all about turbine efficiancy. Of course, none of this take into account any factors other than turbos. (intercoolers and such)

 

[BlackBandit]

And for what it's worth I agree with googs that going twin turbo is probably supposed to yeild the same type of benefit as going to a bigger turbo.

 

[GNDreamin]

This is finally starting to make since to me. Thanks for all of the input. I know it was kind of a bad question with too many variables to consider but the information posted has given me a clearer outlook on how turbos are changing the airflow and the way it affects the engine. Thanks Again

 

[ESP Products]

Going twin is not the same as going to a bigger turbo, in every sense. Example: Bigger turbos, if you look at their maps, make their power at high boost levels and higher RPM levels. Boost raises compression and high RPM is not good for our V-6s. Higher boost is also higher heat. Bigger turbos are designed for biiger engines. Twins, two smaller turbos, spool faster, make power at a lower boost level (efficiently), create less heat and compression. The power range of usable HP is also very broad when compared to a single big turbo. The way it accelerates is also different. Again, this is from our account in building this engine and set-up, and building other single turbo cars using 62-1, T66, and other turbos. There is more to it than just this, but space is limited.

Hope this helps.

 

[GN owner]

The engine can consume only so much air depending on the displacement of the engine. From what I can see if you use two turbos instead of one the total volume to the engine will not increase if the boost is kept the same. The difference is how much air will be flowing through each of the twin turbos which will be lower. In other words to flow 300 CFM through one turbo you will only be flowing half that amount through each of the twin turbos if all of the turbos are the same. This will result in less heat buildup in the intake charge. Thus as an engine accelerates this results in a greater reserve amount of air being provided in a shorter period of time because the turbos will be working less to keep up with the increase in air demand.

 

[BlackBandit]

I think I see what you're trying to say. I'm responding for clarification, not to be an ***hole. Bigger turbos are (generally) meant for higher flowing applications. However, this does not mean they work better at higher boost (or rpm) levels. It's all about pressure ratio and flow. I can definately see how a twin setup would make more overall power, though probably with less peak hp (which would make a faster car) by spooling faster and spending more time in and around the peak efficiancy zone of the turbo. What turbo does this kit use?

 

[ESP Products]

It sounds like you're starting to get the idea. What we are doing is matching efficiencies (if I spelled that correct), head, cam, turbo(s). If thay are work efficiently with one another they have a synergy ($0.25). The peak power I don't believe is lost, but the average power is greatly increased. We have, up to now, made 505 hp and 570 tq at the tires at 18 psi. That's about 630-640 hp and 700 tq at the engine. The stock Iron heads are being pushed. The kit will support 800 hp if the engine can flow it. That's what we are doing next week. :biggrin: New heads should bring us up about 75 more hp. We will still hold 18 psi.

 

[ESP Products]

The ESP Twin Turbo kit uses 2 T3/T4 turbos. They are larger than stock, but smaller that a TE60. We have had more requests for custom jobs than off the shelf kits. We are now working on an 800-1,200 hp kit. That kit will use turbos close in size to the TE60, but with BB. This kit will actually spool just as fast as the 600-800 hp kit. I'd like to call them Stage 1 and Stage 2 kits, but that would start to get confusing, I think.

Hope this helps.

 

[Pronto]

You could call one Twin and the other Evil Twin...

 

[BlackBandit]

What we are doing is matching efficiencies (if I spelled that correct), head, cam, turbo(s). If thay are work efficiently with one another they have a synergy ($0.25).

synergistic effect. (.50)

For some reason the first couple of times I read your article it sounded like the only change from stock was your turbosetup and that the fact that it was twin drastically increased the peak horsepower at a given boost. That's my bad. I'd like to know the differance in power from a single to twin setup at a specific point in time (say 4500 rpm) 10 of boost (same intake temp) as the differance in power could only come from the exhaust side. I don't imagine it would be a ton, but it would be nice to know which way it would go. Good luck on your next step and let us know how it turns out.

 

[GNDreamin]

Do you also run a lower stall converter with that setup compared to a larger single turbo?....If so roughly how much? If that's the case I bet these would be a pretty cool alternatives for a street/drag applications.

P.S. Maybe you could post a comparison of dyno sheets :wink:. Then we can see the visual differences in the power bands. I think that would be really interesting.

 

[ESP Products]

We have tested the car with a 3200 stall and a 3500 stall. We feel the 3200 worked better. We ahve not changed it back because we are making other upgrades that may require that stall to work well.
I can't scan a dyno sheet just yet but here is a conparison of two similar engines. Our ESP Twin Turbo kit on one and a TE60 on the other.

RPM 3500 4000 4500 5000 5500 6000

TT 415 475 490 501 490 480 HP @ 18 psi Pk 501
60 N/A 360 ^ 400 399 380 N/A HP @ 21 psi Pk 405 (^)

TT 540 ^555 520 475 430 389 TQ @ 18 psi Pk 568
60 350 480 ^ 475 420 375 N/A TQ @ 21 psi Pk 499

This is not exactly Apples to Apples, but you have an idea. Both were done on Dyno-Jets but different machines. That's the best I have right now.
Sorry about the chart - it looks better on my screen.

Have a Happy 4th, to all.

 

[larry33kc]

I read this and see alot of guy's saying things like "the enjine can only consume so much" I think we have to remember that we are FORCE inducted meaning that yes there is a limit to what our motors can take but we are still forcing or craming air into them via Turbos.

Also how much is you TT kits I didn't see a price on your site but was also haveing probs. with the computer