Sequential turbos... do-able?

[chevyinlinesix]

Like I said, if you turned the pump way down you might be okay, but I wouldn't want to take a chance on blowing a motor like that, especially since the engine's oil is circulated through the injection pump.

A DB4 is surely doable, and can be done. Peninsular has them available, as would a Stanadyne dealer. I was told the issue with them would be calibrating them, and it might smoke at lower RPMs. That's just what I was told, and am passing along the information

 

[Woody35]

these 6.5 forums have been bench racing for the last year on this idea and chevyinlinesix i think is the closet on getting there. one turbo i think is adequate for the all 6.5 applications but two is just freaking cool. nothing wrong with smoke at lower rpms.

 

[Woody35]

I believe he means one of Detroit's new designs. Think it's the DD16. They've added an axial turbine (connected mechanically directly to the flywheel) onto the engine's turbocharger exh outlet. Looks like the idea is to extract more of the heat energy still left in the exhaust stream & mechanically add that axial turbine's power output back directly to the flywheel.

cummins is doing something like this with the isx

 

[BigBlueChevy]

these 6.5 forums have been bench racing for the last year on this idea and chevyinlinesix i think is the closet on getting there. one turbo i think is adequate for the all 6.5 applications but two is just freaking cool. nothing wrong with smoke at lower rpms.

I'll second that one. Will i think your definatly on a roll with your truck and there could very well come a time where our 6.5's could very well hit 350hp fully built. I'd love to see that day.

 

[allproroofing]

Hey guys , anyone taken a look at possibly doing a remote mount turbo setup? I don't know how it would do on diesel engines , but I was looking into doing for a hotrod project. They say the remote mount turbo has virtually no turbo lag. Check out ststurbo.com

 

[chevyinlinesix]

If I am reading this right, yes someone has done a remote mount turbo setup. He is now removing it in favour of one mounted close to the engine.

 

[restoguy]

This is the direction I was going in my "you bastards" thread. That's what my random queston was about. Here's my thoughts at this point. It's not about more power, neccessarily. It's about having boost across the whole RPM range without choking the exhaust. A small turbo makes boost at lower RPM, but can't keep up as RPM increases. The larger turbo does very little at low RPM, but as the RPM rises it begins creating boost and keeps up with the needs of the engine. Best-of-both-worlds kind of thing. I hope that everybody is on board with the idea now. It seemed that a few were thinking different. Anyway, I asked about a van/hummer engine fitting in a GMT400 because it is set up for a center mounted turbo, leaving the passenger side of the bay for the second turbo. I think that a set of take-off's from a 6.4L powerstroke might work well, at least as a place to start. It's approximately the same displacement, although it's designed for more horsepower than our engines make. But a van turbo with an ATT might be the ticket for someone who doesn't want to use any Ford related parts on his GM! The 6.4 stuff I've seen has been pretty spendy, but some paitence may be rewarded with a steal that can be used to test this. Someone also mentioned variable geometery turbos. I like that idea too. It achieves, more or less, the same thing with less mechanical complication. The HE351VE on the new 6.7L cummins is a VGT and they are pretty cheap on ebay. The problem is that I'm not aware of a controller for it that would work in our trucks. I think it's just a matter of some electronics, which is out of my leauge, but there are others working on it. If(when) they are successful, it should provide the best power with the best economy, depending on what you are doing with the truck at any given time. It's something I'm going to pursue, and when I know something worth sharing, you can bet I'll let my loyal 6.5 buds in on it!

 

[Slim Shady]

The ATT turbo makes boost across the rpm range. No need to have two turbos. Sometimes things can be over engineered, and be made to complicated for a daily driver. Our engines do not, do so well at high load and low rpm with boost, A V8 was never made for that kind of pulling.

A straight line engine with a long stroke is a low rpm torque motor, there are trade offs for everything, nothing is a free lunch. V* engines inherently are short stroke high rpm motors. We are forgetting basics.

 

[chevyinlinesix]

The ATT turbo makes boost across the rpm range. No need to have two turbos. Sometimes things can be over engineered, and be made to complicated for a daily driver. Our engines do not, do so well at high load and low rpm with boost, A V8 was never made for that kind of pulling.

A straight line engine with a long stroke is a low rpm torque motor, there are trade offs for everything, nothing is a free lunch. V* engines inherently are short stroke high rpm motors. We are forgetting basics.

Making boost across the RPM range isn't the only thing to consider though. With my limited knowledge of turbos, I know that you want to operate a turbocharger as close to it's highest efficiency point as possible. With two turbochargers (or two VGT) you can in fact get near peak efficiency throughout the whole RPM range. One turbocharger cannot cover it all.

 

[Slim Shady]

Making boost across the RPM range isn't the only thing to consider though. With my limited knowledge of turbos, I know that you want to operate a turbocharger as close to it's highest efficiency point as possible. With two turbochargers (or two VGT) you can in fact get near peak efficiency throughout the whole RPM range. One turbocharger cannot cover it all.

All I am going to say is the ATT is designed for our motor, it is the only bolt on kit out there that is affordable. We never had a choice for a different turbo:nono: that was Bolton until recently, and now everyone is a critic :nonod:. NOTHING is good through out the whole rpm range not even a Variable vane turbo. The variable is about as close as you can get to a positive displacement gear or belt driven (Supercharger):thumbsup:. But then you lose horsepower to drive the supercharger, :sad: THERE IS NO FREE LUNCH , everything is a trade off. ):h

I was merely saying that the ATT turbo makes boost acrossed the rpm range not just at higher rpm as was stated in a previous post in this thread. That was missleading information.

How is the dual turbo setup comming?

 

[chevyinlinesix]

No need to have two turbos.

All I was saying is that two turbos are more capable than one turbocharger.

My project is at a near stand still until I get back to work.

 

[SmithvilleD]

Without trying to induce or restart the turbo A - vs - turbo B rehash, I think Slim's point regarding high loads/boost/fueling at low rpms is certainly something to consider on most commonly built 6.5's. Using the 5.9 Cummins for comparison, beyond having the longer stroke & its leverage/low rpm torque design advantages, that engine has a dramatically tougher bottom end & block.

Not saying the 6.5 bottom end can't be improved to be more durable than the original design. Just saying if one builds a turbo setup that's capable of building say 15+ psi below 1500 rpm on a 6.5, I'd suggest carefully considering if you really want to use that capability down too low in the rpm range.

There is some experimental work being done w/ the Holset HE351ve VGT turbo on a 6.5. As discussed previously, one challenge is finding or designing a control mechanism for the VGT that can utilize PCM or aftermarket computer control to maximize the benefits the VGT turbine offers. I suspect the VGT turbine could show some highway fuel economy gains by opening up the turbine as much as possible while maintaining necessary hwy cruise boost levels.

As another DIY'r turbo to consider, the last of the 5.9 Cummins ('04-'06) rated at 325 hp came w/ the Holset HE351CW which I believe is the same compressor section as the later VGT on the 6.7's, but is wastegated. It came on the Cummins w/ the smaller 9cm^2 turbine housing like the HY-35W's had (prolly for v quick spool/emissions reasons). That turbine housing might be a bit restrictive for the healthier breathing 6.5's. I'm checking if the 12cm^2 turbine housings from the common HX-35W's are bolt-on to the HE351CW. This might well be another good 6.5 turbo option for the 6.5. These turbo's compressor sections are optimized for a bit higher pressure ratio range than most 6.5's will want to run, but they're still nicely in the higher efficiency islands where most mainstream, mildly modified 6.5's will pull effectively.

When discussing 6.5 turbo design with folks, I often come across some assumptions I'm not certain are reasonable. 100% volumetric efficiency from 2 valve heads designed in the late 80's strikes me as optimistic. Also, while a 6.5 can be built to pull hard at 3400 rpm for significant amounts of time & do it reasonably reliably, the % of time the engine will spend at that rpm is very limited.

I suspect sizing to meet mass airflow requirments for these assumptions makes some efficiency compromises in the rpm & load operating ranges most 6.5's will spend the vast majority of their time running at. For those like me that are comfortable limiting power goals to the practical fueling limits a chipped DS4 can provide, there's a practical limit to how much turbo a 6.5 can use - as compared to tougher engines with more fueling capability headroom like the Duramax.

 

[restoguy]

I'm not putting the ATT down, Slim. Judging by the reviews of ATT owners, I have no doubt it's an excellent addition to our engines. I plan to put one on my christmas list and I'm excited to try it out. I still want to play with VGT's and sequential twins, just to see where it goes. We got where we are with the 6.5 because people tried some different stuff just to see what happened. Some things worked and some didn't. We kept the winners and took it up another notch. I'm just looking for stuff that doesn't work

 

[Veg_Out]

I'm not putting the ATT down, Slim. Judging by the reviews of ATT owners, I have no doubt it's an excellent addition to our engines. I plan to put one on my christmas list and I'm excited to try it out. I still want to play with VGT's and sequential twins, just to see where it goes. We got where we are with the 6.5 because people tried some different stuff just to see what happened. Some things worked and some didn't. We kept the winners and took it up another notch. I'm just looking for stuff that doesn't work

You will love it!

 

[Slim Shady]

I Am not knocking anyone's idea and the ATT is not the end all be all. It is a good match for our engine. I am sure that there are other combinations that will work.

Lots of work goes into making something that will work reasonably well across the board. I could have made it for towing at x rpm range, and could have made it for off the line grunt, lots of combos. I think that the project turned out well.

 

[Matt Bachand]

I asked Guy to his face about the ATT immediately after seeing the large unit in his rig.. His face lit up and he looked right at me, and said. "Matt, that is THE BEST thing I ever bought for this truck". It was an instant response with complete sincerity.

I will buy the ATT due to ease of install. This is really THE only option for me, as I'm not a fabricator, nor can I tie my truck up. In fact, if it wasn't for the ATT, I woulnd't even consider changing turbos. I like the efficiency. Cooler, better mpg.

I still like talking about other turbo's and duals and remotes, and blowers, and everything else. Very few readers are actually going to take the time and effort to customize a non bolt on turbo and take the effort to fabricate its install. Many will buy an easy to install upgrade kit that dramatically improves areas of the 6.5's range. I will be one of those who buys a kit, for a fantastic price too. I just hope it comes with another Idaho Spud!

 

[Woody35]

nothing beats the ease of installiation and the great towing performance the the Att makes. so what ive heard. but this thread was intended for racing im pretty sure and big hp 6.5s. not your typical 6.5

 

[Slim Shady]

nothing beats the ease of installiation and the great towing performance the the Att makes. so what ive heard. but this thread was intended for racing im pretty sure and big hp 6.5s. not your typical 6.5

These are all true, and the ATT will accommodate all the fuel you are able to put to your 6.5. It compliments any fuel or modifications to the engine you may make.

 

[chevyinlinesix]

These are all true, and the ATT will accommodate all the fuel you are able to put to your 6.5. It compliments any fuel or modifications to the engine you may make.

I don't think that's what he's saying exactly. It seems as though running sequential turbos would have much less pumping losses. It not a matter of simply supplying enough air to the engine, but doing it as efficient as possible at the same time. That way you can make more power from the same amount of fuel.

 

[Slim Shady]

I don't think that's what he's saying exactly. It seems as though running sequential turbos would have much less pumping losses. It not a matter of simply supplying enough air to the engine, but doing it as efficient as possible at the same time. That way you can make more power from the same amount of fuel.

Compound / sequential turbos? one turbo driving another turbo?

or two turbos driven independently of each other feeding the same motor.