More of a book than a post (BB TWINS!)
08-10-2007, 10:14 PM
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Very good read. Your posts always get me thinking.I like the idea of a air to water cooling between stages. I have thought of this but as of yet have not come up with a feasable way to do it.
Joe
Joe
08-11-2007, 01:35 AM
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For a 500rwhp rig, its been done to death. Buy the BD twins, they work well and low spool-up. If your thinking about supercharger, I would like to try a GMC 8-71 sized roots. Lots of air flow, low boost pressure though. If you run the super at 5 psi at idle, a 2-3 pressure ratio turbo will get you to 70psi+ range. I would go with a small a/r ratio on the turbo. Fast spools and you get to 50-60psi. I didn't read the stuff, its too long. Building the twin stuff is way harder than thinking about the prefect turbo. I just re-built my turbos, tons of work tweaking this and that. Imagine welding hot pipes and the air tubes. Lots of playing around. I could build one but it would take time to get it right. I would also keep you cold air tube small as posible. It takes time to fill-up the tubes. I was talking to PDR about building a twin BB garrett. I liked the super idea to but that more work than twins.
08-11-2007, 03:15 AM
#18
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HOHN: Very good read and a lot of thought in the calculations. My question is as to why 500 hp at 2k rpm. I think that widening the powerband of the CTD can be done by using an aftermarket cam and this can get you to go a little higher up in the rpm, needing less torque to get to the desired hp and therefore less troubles with clutches or automatic trannies. Personally I can not imagine a situation where you have the need for a constant 500hp in a pickup truck at a steady 2k rpm. IMO you'd either need to drag some mid-sized building up chillicoote pass (and no way that this is safe going down with a pickup) or you'd most definitely accelerate with any lighter load. I think that your calculations would be valid for a genset, a combine or something like those applications.
Your suggestion of air to water intercooling is good- but I think the problem you are going to get is that the amount of energy going from the air to the coolant of the engine is going to be more than the maximum cooling capacity of the Dodge.
Throwing my 2c into a theorethical discussion... maybe some practical use will come out of it
AlpineRAM
Your suggestion of air to water intercooling is good- but I think the problem you are going to get is that the amount of energy going from the air to the coolant of the engine is going to be more than the maximum cooling capacity of the Dodge.
Throwing my 2c into a theorethical discussion... maybe some practical use will come out of it
AlpineRAM
08-11-2007, 03:31 AM
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Since a lot of the replies thus far have been wondering what my point is (gee, you want 500hp twins? that's original!), I think I should address that.
First, I'm talking about 500hp at 2K rpm. This would be 750hp at 3K rpm for those of you scoring at home. Now, 750hp isn't as common as 500, though certainly we've come VERY far in the last few years.
Secondly, I'm talking about a setup that has essentially ZERO lag, or dang close to it. Meaning, I want to be able to floor it with M4s and get very little if any smoke with the Smarty on #5 or so. I think #9 is impossible to make smokeless with large injectors, but you can bet I'd shoot for that as a goal if I thought it was achievable.
Finally, we're trying to eek out max efficiency without using nitrous, water, or meth-- this has to be truly standalone.
Now, any single aspect of these requirements isn't all that difficult. But building a system that can meet ALL of them is certainly a challenge.
Perhaps I need to explain how lofty a goal I'm shooting for in terms of spoolup. For my purposes here, the stock HX35 is WAY too slow in terms of spoolup. We need to improve the spoolup by a factor of two or better over the stock turbo's ability.
Then, we need to take this much faster-spooling turbo and STILL get it to flow at least as much as the HX35, but ideally quite a bit more.
The spoolup goal we have for the big charger is somewhat lofty as well. We are expecting a large primary turbo to spool as fast as a modestly enlarged single might-- think of a full HX40 or a HTT 62/12 and that's what we want from the BIG turbo.
On top of these lofty spoolup goals, we're still asking the chargers to deliver 73 lb--min of air at a temperature that might honestly be completely unreachable. There's a good chance that you just can't get the outlet temps down as far as you want to.
I may end up having to run a secondary that's marginally smaller than an HX35 to meet the spoolup criteria.
In the end, this is all just conjecture on my part, and it's not until such a system is built and exhaustively tested that I could begin to give firm data. I'm talking about temps AND pressures into the big charger, into the little one, and into the engine itself.
I suspect I'll have to invest in some high-dollar guages with data logging ability. Hence my earlier post on the PLX gauges.
I'm disappointed that there are so few attempts made to use performance turbos on our trucks. The only set of BB twins I know of were the set on Tasha'sEvilTwin's truck, and the fabbing on the set was quite unconventional.
Quite frankly, I'm very disappointed that there is so much groupthink and a love affair with the status quo. "Just get the BD twins". I don't want BD twins. I want JH twins. I want better. I firmly believe that there's ALWAYS a better way to do things, and I'd like nothing more than to demonstrate that.
Unfortunately, the money that was going to fund this project will most likely disappear in paying future medical bills, as we received bad news. So I might just have to put this off for, say, a decade or so
JH
First, I'm talking about 500hp at 2K rpm. This would be 750hp at 3K rpm for those of you scoring at home. Now, 750hp isn't as common as 500, though certainly we've come VERY far in the last few years.
Secondly, I'm talking about a setup that has essentially ZERO lag, or dang close to it. Meaning, I want to be able to floor it with M4s and get very little if any smoke with the Smarty on #5 or so. I think #9 is impossible to make smokeless with large injectors, but you can bet I'd shoot for that as a goal if I thought it was achievable.
Finally, we're trying to eek out max efficiency without using nitrous, water, or meth-- this has to be truly standalone.
Now, any single aspect of these requirements isn't all that difficult. But building a system that can meet ALL of them is certainly a challenge.
Perhaps I need to explain how lofty a goal I'm shooting for in terms of spoolup. For my purposes here, the stock HX35 is WAY too slow in terms of spoolup. We need to improve the spoolup by a factor of two or better over the stock turbo's ability.
Then, we need to take this much faster-spooling turbo and STILL get it to flow at least as much as the HX35, but ideally quite a bit more.
The spoolup goal we have for the big charger is somewhat lofty as well. We are expecting a large primary turbo to spool as fast as a modestly enlarged single might-- think of a full HX40 or a HTT 62/12 and that's what we want from the BIG turbo.
On top of these lofty spoolup goals, we're still asking the chargers to deliver 73 lb--min of air at a temperature that might honestly be completely unreachable. There's a good chance that you just can't get the outlet temps down as far as you want to.
I may end up having to run a secondary that's marginally smaller than an HX35 to meet the spoolup criteria.
In the end, this is all just conjecture on my part, and it's not until such a system is built and exhaustively tested that I could begin to give firm data. I'm talking about temps AND pressures into the big charger, into the little one, and into the engine itself.
I suspect I'll have to invest in some high-dollar guages with data logging ability. Hence my earlier post on the PLX gauges.
I'm disappointed that there are so few attempts made to use performance turbos on our trucks. The only set of BB twins I know of were the set on Tasha'sEvilTwin's truck, and the fabbing on the set was quite unconventional.
Quite frankly, I'm very disappointed that there is so much groupthink and a love affair with the status quo. "Just get the BD twins". I don't want BD twins. I want JH twins. I want better. I firmly believe that there's ALWAYS a better way to do things, and I'd like nothing more than to demonstrate that.
Unfortunately, the money that was going to fund this project will most likely disappear in paying future medical bills, as we received bad news. So I might just have to put this off for, say, a decade or so
JH
08-11-2007, 04:09 AM
#20
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Apart from the complexity of the whole system I think that using two VG turbos could be the key to your spoolup goals. I think that spoolup vs exhaust backpressure at high rpm is one of the factors to balance, and it can be done by an extremely nifty wastegate for the secondary, but I think going VG would be much more efficient. Since you would want to draw a map for the efficiencies of the complete system wiht all the additional variables of VG twins I think you'd be in for a really puzzling job....
I am sad to hear the bad news about your wife and I wish her a speedy recovery.
AlpineRAM
I am sad to hear the bad news about your wife and I wish her a speedy recovery.
AlpineRAM
08-11-2007, 05:58 AM
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OK, I think I found an interesting primary charger alternative.
The GT4202R is quite a bit smaller than the 4518, but would work fairly well.
It's not "loafing" to make the required 73lb or so, but you don't really want to be on the CENTER of the map wide open, anyway. For a streetable turbo with wicked spoolup, you want to be on the ragged edge of the right/top of the map.
Since we need a higher PR on the primary than first thought, we need to re-examine which primary would work better at a higher PR in the mass flow range we seek. We may re-validate the original selection.
here's the map for the GT4508:
For comparison, here's the GT4202:
It looks like the 4202 might be even better for our application. The 4202 has a slightly higher PR capability (notice the narrow, more flame-shaped map) and cannot give you more than 90lb/min.
By comparison, our original choice of the 4508 gives us a turbo with a lot more reserve-- it will go up to 120lb and then some. That's enough for over 750hp, which my HO will never have enough fuel to do. Hence, this compressor is too big.
Going back to the 4202, we can also see that we are maximizing spoolup by sort of "riding the rail" on the surge line. Still, surge will not be an issue because the secondary compressor will draw enough air from the primary to keep the PR where it needs to be.
Finally, the 4202 has a tighter hot side which should give us even more spoolup.
So now we have a GT4202 handling primary duties. This will give us more response onthe bottom in two ways: it spools up faster on its own, and it allows us to go a little smaller on the small charger and gain more spoolup. So, we'd go with a Stg 1 powermax diesel turbo instead of the stg 3. The stg 1 is only rated to 350hp, but will spool incredibly quickly.
So I can now see three possible ways to do BB twins, depending on application.
1) Maximum spool and smoke control, great for towing and fuel-limited HO 24Vs: GT3782R over GT4202.
2) Medium sized twins, just a tiny bit slower to spool, but can support bigger HP and/or bias the response curve to the upper RPM: GT3788R over GT4508R
3) Biggish twins that will spool relatively well and support more than 750hp with a clean tailpipe: GT4094R over GT4718R
I'm hoping Turbonetics puts their maps online sometime soon so we can look at those options as well...
JH
The GT4202R is quite a bit smaller than the 4518, but would work fairly well.
It's not "loafing" to make the required 73lb or so, but you don't really want to be on the CENTER of the map wide open, anyway. For a streetable turbo with wicked spoolup, you want to be on the ragged edge of the right/top of the map.
Since we need a higher PR on the primary than first thought, we need to re-examine which primary would work better at a higher PR in the mass flow range we seek. We may re-validate the original selection.
here's the map for the GT4508:
For comparison, here's the GT4202:
It looks like the 4202 might be even better for our application. The 4202 has a slightly higher PR capability (notice the narrow, more flame-shaped map) and cannot give you more than 90lb/min.
By comparison, our original choice of the 4508 gives us a turbo with a lot more reserve-- it will go up to 120lb and then some. That's enough for over 750hp, which my HO will never have enough fuel to do. Hence, this compressor is too big.
Going back to the 4202, we can also see that we are maximizing spoolup by sort of "riding the rail" on the surge line. Still, surge will not be an issue because the secondary compressor will draw enough air from the primary to keep the PR where it needs to be.
Finally, the 4202 has a tighter hot side which should give us even more spoolup.
So now we have a GT4202 handling primary duties. This will give us more response onthe bottom in two ways: it spools up faster on its own, and it allows us to go a little smaller on the small charger and gain more spoolup. So, we'd go with a Stg 1 powermax diesel turbo instead of the stg 3. The stg 1 is only rated to 350hp, but will spool incredibly quickly.
So I can now see three possible ways to do BB twins, depending on application.
1) Maximum spool and smoke control, great for towing and fuel-limited HO 24Vs: GT3782R over GT4202.
2) Medium sized twins, just a tiny bit slower to spool, but can support bigger HP and/or bias the response curve to the upper RPM: GT3788R over GT4508R
3) Biggish twins that will spool relatively well and support more than 750hp with a clean tailpipe: GT4094R over GT4718R
I'm hoping Turbonetics puts their maps online sometime soon so we can look at those options as well...
JH
08-11-2007, 06:37 AM
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OK, so this is turning almost into a blog!
Something else worth noting is this: The Garrett turbos that are "designed" for our trucks are the GT3782R (stg1 and 2) and GT3788R (stg 3).
The Stg 3 turbo, the GT3788R is really just a GT4088R that's been fitted into a GT37 frame. Why not just run a 4088? Well, the 4088 has a T4 flange that would require adapting, while the 3788R has a T3 flange that will bolt right up to the factory manifold.
If you have yet to buy an ATS or HTT manifold, it's worth considering getting the bigger T4 flange version and bolting on the 4088R turbo. The slightly larger passages would not be as restrictive at a given flow rate, I suspect.
More importantly, the 4088 has a V-band flange outlet, instead of the stupid 4-bolt mount of the 3788. That means you can avoid having to use that crummy restrictive adapter that Garrett includes with the Cummins-specific turbos that's known to make EGTs soar.
Justin
Something else worth noting is this: The Garrett turbos that are "designed" for our trucks are the GT3782R (stg1 and 2) and GT3788R (stg 3).
The Stg 3 turbo, the GT3788R is really just a GT4088R that's been fitted into a GT37 frame. Why not just run a 4088? Well, the 4088 has a T4 flange that would require adapting, while the 3788R has a T3 flange that will bolt right up to the factory manifold.
If you have yet to buy an ATS or HTT manifold, it's worth considering getting the bigger T4 flange version and bolting on the 4088R turbo. The slightly larger passages would not be as restrictive at a given flow rate, I suspect.
More importantly, the 4088 has a V-band flange outlet, instead of the stupid 4-bolt mount of the 3788. That means you can avoid having to use that crummy restrictive adapter that Garrett includes with the Cummins-specific turbos that's known to make EGTs soar.
Justin
08-11-2007, 07:17 AM
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OK, so this is turning almost into a blog!
Something else worth noting is this: The Garrett turbos that are "designed" for our trucks are the GT3782R (stg1 and 2) and GT3788R (stg 3).
The Stg 3 turbo, the GT3788R is really just a GT4088R that's been fitted into a GT37 frame. Why not just run a 4088? Well, the 4088 has a T4 flange that would require adapting, while the 3788R has a T3 flange that will bolt right up to the factory manifold.
If you have yet to buy an ATS or HTT manifold, it's worth considering getting the bigger T4 flange version and bolting on the 4088R turbo. The slightly larger passages would not be as restrictive at a given flow rate, I suspect.
More importantly, the 4088 has a V-band flange outlet, instead of the stupid 4-bolt mount of the 3788. That means you can avoid having to use that crummy restrictive adapter that Garrett includes with the Cummins-specific turbos that's known to make EGTs soar.
Justin
Something else worth noting is this: The Garrett turbos that are "designed" for our trucks are the GT3782R (stg1 and 2) and GT3788R (stg 3).
The Stg 3 turbo, the GT3788R is really just a GT4088R that's been fitted into a GT37 frame. Why not just run a 4088? Well, the 4088 has a T4 flange that would require adapting, while the 3788R has a T3 flange that will bolt right up to the factory manifold.
If you have yet to buy an ATS or HTT manifold, it's worth considering getting the bigger T4 flange version and bolting on the 4088R turbo. The slightly larger passages would not be as restrictive at a given flow rate, I suspect.
More importantly, the 4088 has a V-band flange outlet, instead of the stupid 4-bolt mount of the 3788. That means you can avoid having to use that crummy restrictive adapter that Garrett includes with the Cummins-specific turbos that's known to make EGTs soar.
Justin
The 4088 WILL NOT spool like you want it too...even with a custom .68A/R housing. The 3788 (which I haven't used, but basing opinions from a 3782) will outspool it.
Now once I get the Helix 2 and port work installed in a couple weeks, I'll let you know how she spools
Chris
08-11-2007, 09:46 AM
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Cliff(Dieselfreak) did something like this combo a year or 2 ago after much thought and calculation. He is over on NWB site. It would be a shame to see you have to run 70psi of boost to accomplish your goal. You may find it to be possible to do with less.
08-11-2007, 11:55 AM
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Cliff runs a HX40 and a T-4 GT4202 1.15R.
After reading the first post I thought GT4202 way before the GT4508. You have to remember that you sacrafice drive pressure for quick spool up. So the faster a turbo spools (ie. the tighter the housings) the higher the drive pressure is going to be. There are small ways to get around drive pressure but they include running larger or more "open" turbine wheels with tighter housing. The problem is getting the housings you want to do what your trying to do. Also remember that a T-4 manifold/housing will flow more at the expense of spool up. So essentially everything that spools fast has to deal with higher drive pressures.
After reading the first post I thought GT4202 way before the GT4508. You have to remember that you sacrafice drive pressure for quick spool up. So the faster a turbo spools (ie. the tighter the housings) the higher the drive pressure is going to be. There are small ways to get around drive pressure but they include running larger or more "open" turbine wheels with tighter housing. The problem is getting the housings you want to do what your trying to do. Also remember that a T-4 manifold/housing will flow more at the expense of spool up. So essentially everything that spools fast has to deal with higher drive pressures.
08-11-2007, 07:39 PM
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Thanks for posting, Nathan.
I haven't PMd cliff or read any of his postings in quite awhile, and I'd forgotten that he was working on a setup that reflected my priorities.
What this has me coming back to is just how much spool does a person need? I imagine that there is DEFINITELY a point of diminishing returns, in that you find yourself adding, say, 50% more restriction to get 10% more spoolup.
Anecdotally, my truck "feels" like the stock turbo is already on the restrictive side of that optimum. From what I understand, the spoolup difference between a 12cm and 14cm housing on an overfueled HX35 is negligible. That tells me we've gained efficiency and not given up much if anything in the spoolup department.
The other thing I come back to is this: the larger the housing, the more efficient the the turbine, in general.
Another observation is that the "spoolup" portion of the stock turbo that's lacking isn't the threshold, but rather the rate of shaft acceleration. So I have a little room to work with in the boost threshold area, and the faster acceleration of a BB CHRA should be just about what I'm looking for.
I'll have to blow the dust off my NWB account and touch base with Cliff again.
Justin
I haven't PMd cliff or read any of his postings in quite awhile, and I'd forgotten that he was working on a setup that reflected my priorities.
What this has me coming back to is just how much spool does a person need? I imagine that there is DEFINITELY a point of diminishing returns, in that you find yourself adding, say, 50% more restriction to get 10% more spoolup.
Anecdotally, my truck "feels" like the stock turbo is already on the restrictive side of that optimum. From what I understand, the spoolup difference between a 12cm and 14cm housing on an overfueled HX35 is negligible. That tells me we've gained efficiency and not given up much if anything in the spoolup department.
The other thing I come back to is this: the larger the housing, the more efficient the the turbine, in general.
Another observation is that the "spoolup" portion of the stock turbo that's lacking isn't the threshold, but rather the rate of shaft acceleration. So I have a little room to work with in the boost threshold area, and the faster acceleration of a BB CHRA should be just about what I'm looking for.
I'll have to blow the dust off my NWB account and touch base with Cliff again.
Justin
08-11-2007, 07:41 PM
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I still think its been done why bother. The BD twins would work as good or better than your combo. I'm still trying to figure out why the supercharger doesn't work, at least in Hohn mind. Its been done too. That where the GMC6-71 comes from off a 2 stroke diesel. Have you even figured out how the exhaust down tube is going to work? How about wastegates? I'm not up on the garretts, are these turbo internally wastegated? Call me lazy but I rather buy one at a cheaper price than build a more expensive set that spools the same or worse. Buy the BD twins, a helix cam, smarty and SO pump. Its less money, more power and decent spools. IMO
08-11-2007, 08:42 PM
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Just curious the hole twin setup has me a little confused, I don't mean to high jack this thread but can a guy use a 62 for the big turbo and the stock charger for the small? If so where do you come up with the plumbing for such a setup?? I'm just wondering if it will work at all? Chris
