Alright Soulezoo, let's build a set of Garrett twins.
05-21-2012, 11:33 AM
#1
Registered User
Thread Starter
Alright Soulezoo, let's build a set of Garrett twins.
Soulezoo,
I think I want a set of twins in between your first set and current set of twins. I was going to get MPI to make my piping set. I am looking for a max
of 1250-1300 EGT's around 750 hp with good spool. Only mods I will be adding is Hamilton valve springs, a little water, and head studs.
Just inspected by current turbo and the compressor while is rubbing the housing just a little. So much for longevity of a BW bushing charger. I only have about 50,000 miles on the turbo.
I think I want a set of twins in between your first set and current set of twins. I was going to get MPI to make my piping set. I am looking for a max
of 1250-1300 EGT's around 750 hp with good spool. Only mods I will be adding is Hamilton valve springs, a little water, and head studs.
Just inspected by current turbo and the compressor while is rubbing the housing just a little. So much for longevity of a BW bushing charger. I only have about 50,000 miles on the turbo.
05-23-2012, 12:40 PM
#3
DTR 1st Sergeant
patience grasshopper, I just saw this.
Nathan's made a number of these BB sets since I've done mine and he may have a different opinion-- but there are a number of ways to skin that cat.
One of the oddities of the Garretts though is in seen EGTS-- so you can't really use that as your measuring stick. Let me try to explain this way:
Take an engine and with a BW turbo that puts out X lbs/min of air, let's say the engine dynos at 500hp with the given tuning and mods. Let's say max egt for this is 1300*. Now keeping the same engine and tuning identical, the only change is to a Garrett BB turbo that puts out the same X lbs/min of air as the BW turbo, the result is usually an increase in HP (for our virtual comparison let's say it is now 515 hp) and egts will show 1400-1450*.
Now conventional wisdom would suggest that the BW having the lower egt should be able to have more headroom and provide more power, or is at least providing more cooling air to achieve the lower egt. Dyno tests and other empirical evidence suggests this is not the case.
It is well documented that a GT4508r will support more HP (with much faster spool) than an s480 with race cover that provides 3-5 more lbs/min of air. Why/how? I don't know.
I can tell you I have seen conventional turbos producing egts of 1500* melt pistons and Garretts hit 1600* under the same conditions and be fine. Why/how? I can't explain that. I've seen it enough though to be comfortable putting it in print for all to see and be subject to the inevitable doubts and/or ridicule.
I do not suggest that folks take this information and try it for themselves... let caution be your guide.
So what I do suggest is that you size the chargers to the HP you wish to support and then use water (which you should be using at 750hp anyway) to get egts where you want them. It's best to get a good system that you can tailor a "spraying curve" (as opposed to a system that just opens fully at a given psi).
For the chargers and that given HP, I am inclined to suggest the gtx3582r over a GTX4508r.
On the 3582, I would use the .82ar exhaust housing, weld the internal wastegate shut (IMO the big garrett drawback is a small internal wastegate, but it is designed for the intended purpose, which is not twins) and employ a 44mm external gate. On the gtx4508, use the 1.28ar EH.
That will provide the best performance and compromise between low end and top end support while keeping drive pressure in check. Others may point to using a stage 3 gt3788r as a lower cost option and that is a good choice too using the .89ar. Tom at Turboresource makes a good modified version of this.
I see you have flux 1.6 stix. You'll need flux 3.3-3.5 to get 750.
Nathan's made a number of these BB sets since I've done mine and he may have a different opinion-- but there are a number of ways to skin that cat.
One of the oddities of the Garretts though is in seen EGTS-- so you can't really use that as your measuring stick. Let me try to explain this way:
Take an engine and with a BW turbo that puts out X lbs/min of air, let's say the engine dynos at 500hp with the given tuning and mods. Let's say max egt for this is 1300*. Now keeping the same engine and tuning identical, the only change is to a Garrett BB turbo that puts out the same X lbs/min of air as the BW turbo, the result is usually an increase in HP (for our virtual comparison let's say it is now 515 hp) and egts will show 1400-1450*.
Now conventional wisdom would suggest that the BW having the lower egt should be able to have more headroom and provide more power, or is at least providing more cooling air to achieve the lower egt. Dyno tests and other empirical evidence suggests this is not the case.
It is well documented that a GT4508r will support more HP (with much faster spool) than an s480 with race cover that provides 3-5 more lbs/min of air. Why/how? I don't know.
I can tell you I have seen conventional turbos producing egts of 1500* melt pistons and Garretts hit 1600* under the same conditions and be fine. Why/how? I can't explain that. I've seen it enough though to be comfortable putting it in print for all to see and be subject to the inevitable doubts and/or ridicule.
I do not suggest that folks take this information and try it for themselves... let caution be your guide.
So what I do suggest is that you size the chargers to the HP you wish to support and then use water (which you should be using at 750hp anyway) to get egts where you want them. It's best to get a good system that you can tailor a "spraying curve" (as opposed to a system that just opens fully at a given psi).
For the chargers and that given HP, I am inclined to suggest the gtx3582r over a GTX4508r.
On the 3582, I would use the .82ar exhaust housing, weld the internal wastegate shut (IMO the big garrett drawback is a small internal wastegate, but it is designed for the intended purpose, which is not twins) and employ a 44mm external gate. On the gtx4508, use the 1.28ar EH.
That will provide the best performance and compromise between low end and top end support while keeping drive pressure in check. Others may point to using a stage 3 gt3788r as a lower cost option and that is a good choice too using the .89ar. Tom at Turboresource makes a good modified version of this.
I see you have flux 1.6 stix. You'll need flux 3.3-3.5 to get 750.
05-23-2012, 01:17 PM
#4
Registered User
Thread Starter
I agree with you on the internal wastegates for a Garrett, external is the way to go. How did you position your nozzles for your water system? Not too worried about the stix's yet. Can get them upsized later.
05-23-2012, 02:29 PM
#5
DTR 1st Sergeant
For my water injection, I have two systems married together done as I advanced in power. So it may not be applicable.
However, I have on one system 2 625's installed in the intake plenum. One by #6 and one by #1. Then on my other system, all 3 nozzles are installed in the intake horn (the plastic one) a 175, 375 and a 625. That one is a snow max mpg system and works great.
I have 3 egt probes installed and the funny thing I have found is that on my engine #1 and #2 cylinders are always hotter than #5 and #6. That is different than conventional wisdom says, but the probes don't lie. And I have moved them all around thinking that one was reading different than the others, well, that wasn't the case. They are all very close to one another.
However, I have on one system 2 625's installed in the intake plenum. One by #6 and one by #1. Then on my other system, all 3 nozzles are installed in the intake horn (the plastic one) a 175, 375 and a 625. That one is a snow max mpg system and works great.
I have 3 egt probes installed and the funny thing I have found is that on my engine #1 and #2 cylinders are always hotter than #5 and #6. That is different than conventional wisdom says, but the probes don't lie. And I have moved them all around thinking that one was reading different than the others, well, that wasn't the case. They are all very close to one another.
Thread
Thread Starter
Forum
Replies
Last Post
Spooler
3rd Gen High Performance and Accessories (5.9L Only)
5
04-16-2012 09:17 AM
Red3quarter
Other
541
12-12-2009 11:12 PM