ok, so what is the difference besides about $1900?
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T-88 vs. HT3B
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I cant find crap on the HT3B! However I can find heaps of stuff on the T88. The T88 flows 1450 CFM, and has the ability of moving enough air to make 1200 HP on a gasser. At a PR of 2. 2 and a flow rate of 100 LBM/min its efficiency is at a whopping 74%. At 2. 0 and 70 LBM/min it goes up to 80%. The T88 is spendy, however the HT3B is not in comparison. Unless there is another reason other than price why a HT3B is better than a T88 with a "Q"trim turbine and a 22CM housing please tell me.
would someone please throw me a bone?
would someone please throw me a bone?
Just curious what the over all physical size is of the T-88 and what the inlet ans exhaust are, my guess(with lookin at both) is the HT3B is about like a 91MM, guess I need to go look at some gasser stuff. Try doing a search on the net for Garrett or Swishter(sp) mine is a Garrett. All need the Piers treatment, I've already had one person(locally) that wanted to take mine a part to see what he did to it, answer... ... ... ... UUUUUHHHHH... ... ... NO
Jim
Jim
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well the inducer on the T88 is 88mm, and the exducer is 109mm, or 3. 64 and 4. 6 inches respectively. I have no data on the turbine side.
Just found out that the T-88 will move more air more efficiently than the HT3B. Then other than cost why is the HT3B used?
Cost, and perhaps durability?
hmmmm, durability for the turbo or the engine?
The HT3B/HX35 combo at 70 PSI can have a final discharge temp of 724F where the T88/HX40 final discharge temp at 70 PSI is a bit lower at 587F.
this is with 60F ambient air at sea level. It kinda sucks that the HT3B drops to about 60% efficient at the same flow rate as the T88 where the T88 is closer to 78% efficient.
The HT3B/HX35 combo at 70 PSI can have a final discharge temp of 724F where the T88/HX40 final discharge temp at 70 PSI is a bit lower at 587F.
this is with 60F ambient air at sea level. It kinda sucks that the HT3B drops to about 60% efficient at the same flow rate as the T88 where the T88 is closer to 78% efficient.
Dang dude, you really are looking into it aren't you, cool that you have the knowledge or ability got figure the knowledge. There is a few things I would like to try and/or test on like back pressure and just what boost the HT is putting out at 60 PSI. Thanks for the info but 724F make my butt hurt, guess that's why the silicone boots are swelling just a tad
Jim
Jim
This is very long, and I am not the author.
An adiabatic process is one in which heat does not enter or leave the system. Though this is not strictly true in a turbocharger, it is a close approximation over a very short time period. An adiabatic temperature or pressure change can be calculated from the volume change using the following two equations (which usually are found in your physics texts):
(T2/T1) = (V1/V2)^g-1 and (P2/P1) = (V1/V2)^g,
where g is the ratio of air's heat capacity at constant pressure to air's heat capacity at constant temperature; T1, P1, and V1 are the initial temperature, pressure, and volume; and T2, P2, and V2 are the final temperature, pressure, and volume. Taking the log of both of these equations, and knowing that log ab = b log a, the following equation relating adiabatic temperature change to pressure change can be derived:
(T2/T1) = (P2/P1)^[(g-1)/g].
Physics texts will tell you that for the diatomic gasses like N2 and O2 in air, g is assigned a value of 1. 4. By substituting and rearranging we get
T2 = T1 x (P2/P1)^0. 286.
Actually, the exponent in the above equation that you usually see is 0. 283, meaning that g is actually closer to 1. 395. You can use either number, the difference it makes in the calculations is about 0. 25%. We need to note that temperature in all of these equations must be absolute temperature in either Kelvin (centigrade scale) or Rankine (Fahrenheit scale). If you want to work in C then K = C + 273. 15. If you are more comfortable with F then R = F + 459. 69. Also note that 1 degree on the Kelvin scale equals 1 degree on the Centigrade scale, and 1 one Rankine degree equals 1 Fahrenheit degree. I prefer the Fahrenheit scale and will round off 459. 69 to just 460 for the examples here. I'll assume that we are at sea level at a standard pressure of 14. 7 psi with an ambient air temperature of 70F.
The expression (P2/P1) represents the turbocharger compressor pressure ratio (PR), where P1 is atmospheric pressure on the inlet side and P2 is the absolute pressure on the outlet side. T1 is the air temperature entering the compressor and T2 is the air temperature leaving the compressor.
Many people think that 12 psi in the manifold is a moderate boost level so I'll use that as an example. If we can assume there is a 2 psi pressure loss from the turbo to the manifold, then the PR at the compressor is about 1. 95 ( (14 +14. 7)/14. 7). Let's also assume we manage to keep the intake air temperature down to 80F (or 540R). The air temperature leaving the compressor, due to adiabatic heating only, would be 194F which is 654R = 54R x (1. 95)0. 286. This is an increase of 114F! But the air is actually hotter than that.
Turbochargers compress the air by increasing the velocity of the molecules. When the air molecules don't move in a direction toward the intercooler (IC), they serve only to heat the air. The more the air is heated above that predicted by adiabatic compression, then the less efficient the turbocharger is. Compressor flow maps usually show at various flow amounts and pressure ratios the measured efficiency of a turbocharger. Compressors usually operate in the 55-75% efficiency range depending on engine load, pressure ratio, turbine speed, and compressor size (65-70% is average, 75% or more is where we would like to be).
When we factor in compressor efficiency (CE) the final temperature of the air leaving the compressor is
T3 = T1 + (T2-T1)/CE.
If compressor efficiency is 70% in the above example, then the final temperature is 242F, more than hot enough to boil water. If we increase the PR to 2. 36 (18 psi manifold and 2 psi IC loss), the temperature would increase to 295F. These high temperatures explain why intercoolers are so important when boost pressure is above a few psi.
The intercooler of course is supposed to cool the air. Intercooler efficiency, IE, can be calculated by measuring the air temperature going into the intercooler, Tin, the air temperature leaving the intercooler, Tout, and the ambient air temperature, Tamb.
IE = (Tin-Tout)/(Tin-Tamb) or Tout = Tin - IE x (Tin-Tamb).
High efficiency levels are near 90% and lower levels are toward 50-60%. If an 80% efficient intercooler had been used in the above example, then manifold air temperature at 12 psi boost would have dropped to about 104F = 242F – 0. 8 x (242-70)F. Intercooler air cooling by the way is not an adiabatic process. Ideally, heat is removed from the air without a corresponding decrease in pressure. If you think about it, you'll see that intercooler efficiency is far more important than the efficiency of the turbocharger.
By Jeff Lucius
An adiabatic process is one in which heat does not enter or leave the system. Though this is not strictly true in a turbocharger, it is a close approximation over a very short time period. An adiabatic temperature or pressure change can be calculated from the volume change using the following two equations (which usually are found in your physics texts):
(T2/T1) = (V1/V2)^g-1 and (P2/P1) = (V1/V2)^g,
where g is the ratio of air's heat capacity at constant pressure to air's heat capacity at constant temperature; T1, P1, and V1 are the initial temperature, pressure, and volume; and T2, P2, and V2 are the final temperature, pressure, and volume. Taking the log of both of these equations, and knowing that log ab = b log a, the following equation relating adiabatic temperature change to pressure change can be derived:
(T2/T1) = (P2/P1)^[(g-1)/g].
Physics texts will tell you that for the diatomic gasses like N2 and O2 in air, g is assigned a value of 1. 4. By substituting and rearranging we get
T2 = T1 x (P2/P1)^0. 286.
Actually, the exponent in the above equation that you usually see is 0. 283, meaning that g is actually closer to 1. 395. You can use either number, the difference it makes in the calculations is about 0. 25%. We need to note that temperature in all of these equations must be absolute temperature in either Kelvin (centigrade scale) or Rankine (Fahrenheit scale). If you want to work in C then K = C + 273. 15. If you are more comfortable with F then R = F + 459. 69. Also note that 1 degree on the Kelvin scale equals 1 degree on the Centigrade scale, and 1 one Rankine degree equals 1 Fahrenheit degree. I prefer the Fahrenheit scale and will round off 459. 69 to just 460 for the examples here. I'll assume that we are at sea level at a standard pressure of 14. 7 psi with an ambient air temperature of 70F.
The expression (P2/P1) represents the turbocharger compressor pressure ratio (PR), where P1 is atmospheric pressure on the inlet side and P2 is the absolute pressure on the outlet side. T1 is the air temperature entering the compressor and T2 is the air temperature leaving the compressor.
Many people think that 12 psi in the manifold is a moderate boost level so I'll use that as an example. If we can assume there is a 2 psi pressure loss from the turbo to the manifold, then the PR at the compressor is about 1. 95 ( (14 +14. 7)/14. 7). Let's also assume we manage to keep the intake air temperature down to 80F (or 540R). The air temperature leaving the compressor, due to adiabatic heating only, would be 194F which is 654R = 54R x (1. 95)0. 286. This is an increase of 114F! But the air is actually hotter than that.
Turbochargers compress the air by increasing the velocity of the molecules. When the air molecules don't move in a direction toward the intercooler (IC), they serve only to heat the air. The more the air is heated above that predicted by adiabatic compression, then the less efficient the turbocharger is. Compressor flow maps usually show at various flow amounts and pressure ratios the measured efficiency of a turbocharger. Compressors usually operate in the 55-75% efficiency range depending on engine load, pressure ratio, turbine speed, and compressor size (65-70% is average, 75% or more is where we would like to be).
When we factor in compressor efficiency (CE) the final temperature of the air leaving the compressor is
T3 = T1 + (T2-T1)/CE.
If compressor efficiency is 70% in the above example, then the final temperature is 242F, more than hot enough to boil water. If we increase the PR to 2. 36 (18 psi manifold and 2 psi IC loss), the temperature would increase to 295F. These high temperatures explain why intercoolers are so important when boost pressure is above a few psi.
The intercooler of course is supposed to cool the air. Intercooler efficiency, IE, can be calculated by measuring the air temperature going into the intercooler, Tin, the air temperature leaving the intercooler, Tout, and the ambient air temperature, Tamb.
IE = (Tin-Tout)/(Tin-Tamb) or Tout = Tin - IE x (Tin-Tamb).
High efficiency levels are near 90% and lower levels are toward 50-60%. If an 80% efficient intercooler had been used in the above example, then manifold air temperature at 12 psi boost would have dropped to about 104F = 242F – 0. 8 x (242-70)F. Intercooler air cooling by the way is not an adiabatic process. Ideally, heat is removed from the air without a corresponding decrease in pressure. If you think about it, you'll see that intercooler efficiency is far more important than the efficiency of the turbocharger.
By Jeff Lucius
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Originally posted by CMNS PWR
Thank you sir. Those thermodynamics calculations are very straightforward. I do have texts that explain all of that. I just forgot I had them.
Me too, and I never thought I would be using them in reference to a "Hobby".
Oh, and BTW, please do not call me "sir". I do not squat when I pee.
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looks like one of the 2 books i just got the other day......
I have heard of twins on our trucks using a Garret T-type turbo as the big turbo, and working VERY well. As for rather it is the T-88 I don't know. It would make perfect since though after seeing the numbers compaired to the Ht3B. I can not find squat on the Ht4B.
Let us know what you decide on DF.
Andrew
I have heard of twins on our trucks using a Garret T-type turbo as the big turbo, and working VERY well. As for rather it is the T-88 I don't know. It would make perfect since though after seeing the numbers compaired to the Ht3B. I can not find squat on the Ht4B.
Let us know what you decide on DF.
Andrew
Re: looks good to me!
Ugh, you just had to remind me of T/s diagrams, steam tables, Mollier. Acadamia is a PITA.
Now all we have to do is plug the numbers onto a 'puter.
Now with all this, does anyone have any more input on my Turbo research?
Originally posted by banshee
I'm with Daniel... everything looks good and is right on the money. Reminds me of those 5 page problems on steam systems in Thermo 2 in college Oo.
John
Ugh, you just had to remind me of T/s diagrams, steam tables, Mollier. Acadamia is a PITA.
Now all we have to do is plug the numbers onto a 'puter.
Now with all this, does anyone have any more input on my Turbo research?
Originally posted by CMNS PWR
Only 5 pages? Johnner, I guess you never had quantum mechanics! Oo.
That was fun!
hey, what was the difference between Thermal, Prompt, and Fast Neutrons?
Geez, I really am a Geek!
the maps on the big t-series just get prettier and prettier as the numbers go up... the pressure ratios they can run at and still remain efficient are awe inspiring... and you don't really lose much by going higher... obviously a heavier wheel will take a little longer to get up to speed, but you don't pay a surge or efficiency penalty really... my buddy had a T76 on a fairly stock 302... that thing went 10. 70's with a rediculously cheap combo! LOL! most people told him to go with a 60-64mm turbo, but he got a screamin' deal on the 76... he added some race fuel and cranked up the boost, and the rest was history.
Garrett doesn't seem to be able to produce a small turbo that operates at high 3 to low 4:1 pressure ratios... Holset seems to have the lock on that department...
but when you're talking about fairly large CFM at fairly high pressure ratios, Garrett is where you need to look... . check out the maps, they just get fatter and taller!! LOL!
the number following the "T" is the minor measurement of the compressor wheel in milimeters...
not sure what an HT3B major/minor diameters are.
also, you gotta realize that all those "T" series turbos are just Garrett bits and pieces... for example, the "T76" uses the compressor wheel off a 60 series Detroit. companies like Precision and Turbonetics are making a killing on that stuff... granted, they're paying to have their own housings cast, and that's not cheap, but their R&D is fairly cheap because they're just taking existing wheels and mixing/matching them and putting them in a common center section... .
hell, even Vortech uses old Garrett stuff for their blowers... the S-trim and R-trim compressor wheels are just old Caterpillar T-18 compressor wheels... sluggish/crappy old wheels IMHO, but they make a killing off 'em! LOL!
sorry for the tangent.
you can get a rough CFM idea based on minor diameter, but blade pitch/curve/count/etc. is where your pressure ratio efficiency comes into play.
you can't judge a book by its cover... different wheels of very similar diameters will have totally different efficiency ranges as far as boost is concerned.
Forrest
Garrett doesn't seem to be able to produce a small turbo that operates at high 3 to low 4:1 pressure ratios... Holset seems to have the lock on that department...
but when you're talking about fairly large CFM at fairly high pressure ratios, Garrett is where you need to look... . check out the maps, they just get fatter and taller!! LOL!
the number following the "T" is the minor measurement of the compressor wheel in milimeters...
not sure what an HT3B major/minor diameters are.
also, you gotta realize that all those "T" series turbos are just Garrett bits and pieces... for example, the "T76" uses the compressor wheel off a 60 series Detroit. companies like Precision and Turbonetics are making a killing on that stuff... granted, they're paying to have their own housings cast, and that's not cheap, but their R&D is fairly cheap because they're just taking existing wheels and mixing/matching them and putting them in a common center section... .
hell, even Vortech uses old Garrett stuff for their blowers... the S-trim and R-trim compressor wheels are just old Caterpillar T-18 compressor wheels... sluggish/crappy old wheels IMHO, but they make a killing off 'em! LOL!
sorry for the tangent.
you can get a rough CFM idea based on minor diameter, but blade pitch/curve/count/etc. is where your pressure ratio efficiency comes into play.
you can't judge a book by its cover... different wheels of very similar diameters will have totally different efficiency ranges as far as boost is concerned.
Forrest
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Issue 128 – Digital Version
Digital Magazines
FREE!
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Renew
Subscribe
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Back Issues
Subscription Status
Address Change Form
Buyer's Guides
Ram Diagnostic Trouble Codes
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What Makes Us Tick?
Product Showcase
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