When folks refer to a turbo as a T76 for example, is that based on the inlet or the size of the transducer wheel?

 

impeller usually.

 

Well unfortunately even that number is becoming less meaningful. My new turbo is a Garrett/PTE GT42-2. The turbo is a ball bearing 1.16 AR 80mm unit. I have no idea what the 42 refers to.

In the old days the 76 would have referred to the impeller size, now I am not sure what it means any longer.

 

Here is a short explanation, since this can get long. All your standard T series turbos are measured at the compressor inducer. Like a T76 is a 76mm Inducer/ 102mm Exducer on the compressor side. Now the GT turbos have changed in naming. The GT-42 is offered in 2 versions. A 94mm and 102mm, those number stand for the Exducer side of the compressor. So the GT42 102mm turbo is basically a new GT version of the T76, since its also a 102mm exducer and the 94mm version is ~ a T70 or so. Now the trims are measured by compressor trim=(inducerdiameter^2/exducerdiameter^2)*100 , and same for the turbine trim side. All this means is as the trim size is increased, the wheel can support more air flow. Now on to the naming structure for these garrett's. The way they are always named is the basic GT model format is GTXXYYZZZZ. The first two positions are always GT for Garrett. Then Position "XX" tells you the turbine family and bearing system that the turbo uses. Position "XX" is considered the model # and is often used as the name for the turbo. Now position "YY" tells you the compressor wheel the turbo uses. Lastly position "ZZZZ" is used to tell you features of the turbocharger. Not all four positions are always used. Ok here is an example, I have a "GT35R" sitting in front of me here and I want to know what this thing has in it. Well the GT35R is the short name and it just the base model code for this turbo. There are many other variables to this turbo. Now to see exactly what the turbo is we would have to use the full name which is "GT3540R 56 trim". Ok first the "R" means this is a BB unit. The 40 means this turbo uses the wheel from the GT40 and the 56 trim means it uses the 82mm exducer wheel. Their are also other naming tricks used by other companies like PTE when talking about the GT40 stuff they sell. Another new unit that has passed through my hands was the GT40-67. Well that only means its using a GT40 chassis with 67mm compressor wheel measured at the inducer. You will in the very near future see PTE using the GT45-80, GT45-82, and GT47-88...plus some new others. BTW the GT45 is a nice piece, and should work very well on our cars. The GT47, GT60 and GT70 are huge, and I don't think spool would be good at all unless its a purpose built race motor only.

Jose

 

Wow, that's an answer

I was under the impression the GT42 was an 80mm turbo. At least I now understand the coding better, Thanks for the info

 

FFW Drag Radial/Street Outlaw/Pro Rules:

Measurement will be at the leading edge of the compressor wheel where it meets the compressor inlet housing. All incoming air is required to travel through the inducer from the front or leading edge of the inducer and cannot be introduced to the turbine blades through ports or slots of any kind.


NMRA Drag Radial/Super Street Outlaw/Pro 5.0 Rules (Sizes/Dimensions vary per class):

Turbocharger must be of conventional impeller and housing design and type. Turbocharger is limited to a choice of two turbochargers (at two weight breaks): [a] maximum size of 80.0 mm/3.150" - inducer wheel diameter at the point where the leading edge of the compressor wheel meets the inlet housing. Inlet housing is permitted a maximum inlet diameter of 3.230" where the leading edge of the compressor wheel meets the housing. [b] maximum size of 82.0 mm/3.228" - inducer wheel diameter at the point where the leading edge of the compressor wheel meets the inlet housing. Inlet housing is permitted a maximum inlet diameter of 3.308"where the leading edge of the compressor wheel meets the housing. Compressor wheel to housing clearance must maintain a maximum of 0.080" clearance beginning from a) where the leading edge of the compressor wheel meets the inlet of the compressor housing to b) the transition point where the trailing edge of the compressor wheel meets the volute. All air entering the turbocharger must pass through the turbocharger inlet. Injection of any liquid, gas, or any other substance into the inlet or exhaust housing prohibited. Turbocharger compressor wheel must be constructed of cast or billet aluminum. Exotic material wheels prohibited. Impeller wheel may not be stepped, cut down, or notched to meet impeller tip-to-tip dimension.

 

LEts continue:
Limit Engineering built my hybrid (twins) turbos..here are the specs they gave me:
* 76 mm Turbines... TO4E housing...then something regarding "350"
* GT42 56 mm compressors, T3 housings...
The a/r is .63
What exactly am I playing with and do these jive.

 

They make a GT-45?? The 42 compressor wheel is optioned at either about 74 and 76, The GT47 is optioned either 80mm or 88mm.....

Andy

 

This is good information. That's what this forum should be about.

 

Jammer, the 76mm is probably the inducer size. The T04E is the compressor cover used, which if I remember correctly "don't have the papers in front of me" is a 3" inlet with 2" discharge. The 350 is probably a 360 which is a 360 degree thrust bearing vs a 270 degree. The GT42 and 56 mean the GT42-56trim, which is equivalent to about a 70mm turbo since it uses a 94mm exducer. The .60 is a A/R ratio for the exhaust.

Andy yes they make a GT45, its not well known yet, but it will be. It is offered in a 80mm version. The GT47 is 80mm and 88mm, but its a TV style flanged turbo.

Jose

 

Have you heard anything about the masterpower turbos? i found this site, they have nomenclatures listed similar to the garret and turbonetics names. not sure if the turbos are actually the same or not, maybe you could take a look and let us know? they have the measurements on the site by each turbo and one is named the GT45 and one is a T70, these look like the largest on the site from whatb i can see!

Link:
http://www.partsexpressonline.com/highperformance.htm

 

Yes I deal with Master Power. They are nice units, basically the same as a Garrett unit, but the bearing structure is more solid. They don't offer the newer style wheels though for the T series units. But they are a very cost effective choice to the other brands.

Jose

 

JZ 97 SS 1500,

sorry for hijacking this thread, a while back when i first began this project, i purchased a T-70 Master power is the reason i ask, I purchased a 1.15 A/R exhaust housing for it as i don't really car about fast spool at low rpm as much as a nice pull up top, and to help alleviate some exhaust back pressure pre turbo. I am not sure exactly how this turbo will peform, but have heard several good things about them being quick spoolers anyhow. the turbo will be going on a 355 8.9:1 motor with ported heads/intake and i think i have decided to stay with a stock LT4 camshaft for the best street manners possible. do you think i will run out of turbo on this setup? your input is greatly appreciated!

Chris

 

Depends on what hp your shooting for. The 1.15 A/R will really help since the MP T70 only comes with a .68 A/R. If your shooting for big numbers the smaller p-trim wheel will become a large restriction. I personally would go with the MP GT-45, its a nice unit and will make good power.

Jose

 

well, as far as power output goes, for starters just getting all the various systems on the car together and functioning properly as well as all the custom fabrication completed and made road worthy for the long haul, with this turbo I am hoping for at least upper 500rwhp maybe in the 600rwhp range with 112 or 116 gas, the down pipe will be 3.5" and the manifolds and plumbing is all larger sized for future upgrades as well as the mounting location of the turbo, i left room in all directions to grow later on. using a 50mm HKS wastegate, 50mm Tial BOV, and a large FMIC by spearco with lots of flow in it. 3" aluminum intake plumbing.. basically, I want to make sure the turbo is the shortcoming because once everything else is in place it will be the easiest thing to upgrade down the road when i get used to the power the T-70 makes. the fuel system is twin intank GSS340 walbros with dual -6AN feed lines to an external Aeromotive regulator with a single -6AN return line, and probably the 60lb motron High Z injectors. do you think that power goal is reasonable? the motor is fully forged and putting power down through a mcleod twin disc. the tranny is the ZF vette tranny, an the rearend is a Dana 44, the rest of the driveline will be beefed up as the components fail..lol so lemme know what ya think, Down the road the GT45 is likely what i will go with if the performance of the T70 is up to snuff!

Chris

 

Looks like you covered all your bases well. Those components will do the job easily. The #'s your shooting for shouldn't be a problem with that turbo at all. I think you will be very happy with the results. BTW, the GT45 is nice, but thier are some new ones coming

Jose

 

What GT45 are u talking about? Does Garret make one, that is the next size up from the GT42? Should support about 1300hp right?

 

The GT45 is a 80mm unit and also is offered in an 82mm unit. Should be good for 1200-1250hp. And yes, it is the next step up from the GT42.


Jose

 

BTW, look for some other turbo companies coming into the mix. Look for some borg warner & schwitzer units coming and they are pretty bad.

Jose