Turbonetics with Precision Exhaust Housing

[turbojimmy]

What’s the deal with Turbonetic turbos with Precision exhaust housings? I stumbled across what I think is a fair price for a used Turbonetics T70 BB turbo locally. It has a Precision .85 A/R housing. I’ve already committed to buying it so I’m looking after I’ve leapt so to speak. I’m just curious as to why some of the Turbonetics turbos are this way. I'm assuming it's something the users are/were doing rather than something Turbonetics is/was doing? Doing a search here and on ‘the other’ boards I’ve found more than a few references to Turbonetics turbos that have .85 A/R Precision housings.

Thanks,
Jim

 

[RUQWKNF]

From what I've seen over the years, it's all about the flow potential. The highest flowing 3-bolt Buick housing has been the PTE housing. (Stock Garrett that's been ported, vs T-netics, vs PTE) Not sure if ITS ever made a dedicated 3-bolt Buick housing or not. This is especially true on the 70 series turbos. It's not un-common to see swaps like this. As long as the turbine wheel specs are the same, and the housing will bolt up the same, there are no down sides to mixing the housings, just a bonus of more flow potential. It's all about relieving the back pressure.
HTH

Patrick

 

[turbojimmy]

From what I've seen over the years, it's all about the flow potential. The highest flowing 3-bolt Buick housing has been the PTE housing. (Stock Garrett that's been ported, vs T-netics, vs PTE) Not sure if ITS ever made a dedicated 3-bolt Buick housing or not. This is especially true on the 70 series turbos. It's not un-common to see swaps like this. As long as the turbine wheel specs are the same, and the housing will bolt up the same, there are no down sides to mixing the housings, just a bonus of more flow potential. It's all about relieving the back pressure.
HTH

Patrick

Thanks for the info. The Turbonetics T70Q-trim exhaust wheel seems to be the same size as on Precision's PT71 GTQ? If so then it makes sense to me that the Precision housing would work. I just hope I can spool this thing - the ball bearings should help.

Jim

 

[RUQWKNF]

Unless T-netics started using the exact GT wheel that PTE has been using for 6 years, then there is a difference between the Tnetcis Q trim and the GTQ. The PTE housing will fit over the Q trim wheel and quiet possibly bolt up, but there is alot more gap between the wheel and the tongue of the housing. This could lead to some spool up issues. You need to measure the inducer and exducer of the turbine wheel on the turbo that you have 1st. Then find the part number that is cut into the side of the turbine housings' dp flange surface. See this pic for reference to part number location.

In the above pic, the part number is THB3-76,
TH = Turbine Housing
B = Buick
3 = .63 A/R
76 = 76 "P" trim turbine wheel.

What you are looking for on your housing should read, THB5-80
This would be the correct part number for a .85 A/R housing that is cut specifically for the GT-Q turbine wheel that PTE specifically uses.
Where as the PTE housing will fit over the older Q trim wheel, a turbine housing that was cut for the older Q trim wheel, will not slide over the newer GT-Q wheel.

The GT-Q wheel specs straight from PTEs website are:
3.110" inducer
2.695" exducer
70 trim

Here is a pic that shows you basically how to measure the inducer and exducer of both wheels.

HTH

Patrick

 

[turbojimmy]

Unless T-netics started using the exact GT wheel that PTE has been using for 6 years, then there is a difference between the Tnetcis Q trim and the GTQ.

I have no idea what's been done to this turbo. I had just ASSumed that since it's a "Q" that the housings could be interchangable if the Q-trim wheel was the same size as PTE's. The guy has been using the turbo for a couple of years and hasn't had any trouble with it. I'll check the stamping on the housing when I get it to see what it says.

Thanks,
Jim

 

[turbojimmy]

What you are looking for on your housing should read, THB5-80
This would be the correct part number for a .85 A/R housing that is cut specifically for the GT-Q turbine wheel that [font=+1]PTE[/font] specifically uses.
Where as the PTE housing will fit over the older Q trim wheel, a turbine housing that was cut for the older Q trim wheel, will not slide over the newer GT-Q wheel.

Patrick,

After re-reading your post (multiple times) did you mean to say Turbonetics above?

Thanks,
Jim

 

[bison]

What’s the deal with Turbonetic turbos with Precision exhaust housings? I stumbled across what I think is a fair price for a used Turbonetics T70 BB turbo locally. It has a Precision .85 A/R housing. I’ve already committed to buying it so I’m looking after I’ve leapt so to speak. I’m just curious as to why some of the Turbonetics turbos are this way. I'm assuming it's something the users are/were doing rather than something Turbonetics is/was doing? Doing a search here and on ‘the other’ boards I’ve found more than a few references to Turbonetics turbos that have .85 A/R Precision housings.

Thanks,
Jim

Mine is a turbonetics with a .85 precison ex housing but has a p trim turbine. Spools really fast with the 3000 stall.

 

[RUQWKNF]

The PTE housing is cut for the larger GT-Q turbine wheel, and if T-netics is still using the older Q-trim wheel, the PTE housing will fit over T-netics wheel. But, a T-netics 3-bolt housing cut for a T-netics regular Q-trim wheel, will not slip over a PTE GT-Q wheel unless it has been machined to the GT-Q turbine wheels measurements.
People with combinations like this can learn a lot from the part number that's been cut into the side of the PTE housing. T-netics does talk about a Pro Q trim 10 blade wheel on their Super T series, but they no longer list wheel specs and measurements on their website. It wouldn't suprise me if they have copied the GT-Q wheel by now. A lot of people have been experimenting with the PTE housings on other makers bb turbos for the past 3-4 years, mainly because PTE didn't offer anything BB in their 70 series line up, until just recently. Some have had to have their housings specially machined, others have just lived with the lag.

Patrick

 

[turbojimmy]

Some have had to have their housings specially machined, others have just lived with the lag.

Patrick

I suspect I will fall into the latter category. I'll have to bolt it up and see.

Thanks,
Jim

 

[turbojimmy]

The GT-Q wheel specs straight from PTEs website are:
3.110" inducer
2.695" exducer
70 trim

Sorry to keep asking questions, but you've been very helpful.

The specs on the Turbonetics Q-trim wheel are:
3.111" inducer
2.693" exducer

So I can see why the Precision housing will fit. Is the difference in size enough to affect spool?

Thanks,
Jim

 

[RUQWKNF]

I don't think you'll have a problem. If that turbine wheel has 10 blades, then that is what they call their Pro Q trim wheel, and is almost identical to the GT-Q. Doesn't surprise me that they might have copied the GT-Q.
I think you'll be fine.

Patrick

 

[turbojimmy]

I don't think you'll have a problem. If that turbine wheel has 10 blades, then that is what they call their Pro Q trim wheel, and is almost identical to the GT-Q. Doesn't surprise me that they might have copied the GT-Q.
I think you'll be fine.

Patrick

It does indeed have 10 blades. Unfortunately the roads are covered with salt and will be for quite some time. I won't be able to test it for a while.

Jim

 

[DonnieShort]

Mine is a turbonetics with a .85 precison ex housing but has a p trim turbine. Spools really fast with the 3000 stall.

Did you notice any pick up when you switched to the PTE .85 housing?
I've got a Turbonetics T70 P trim with Turbonetics .82 housing and thought about switching over to the .85 PTE if it would be worth it.

 

[turbojimmy]

Did you notice any pick up when you switched to the PTE .85 housing?
I've got a Turbonetics T70 P trim with Turbonetics .82 housing and thought about switching over to the .85 PTE if it would be worth it.

I talked a little more about it with the guy that sold me the turbo. He did have PTE custom mill the housing to work with the Turbonetics Q-trim wheel. However, given how close they are in specs I'm not sure how much work really needs done.

Jim

 

[bison]

Did you notice any pick up when you switched to the PTE .85 housing?
I've got a Turbonetics T70 P trim with Turbonetics .82 housing and thought about switching over to the .85 PTE if it would be worth it.

Mine came from a boardmember with the .85 precision ex housing. So i have no comparison. Also note that its a p-trim, not a Q or GTQ and has the ball bearing option. Its a real tire burner with spool up in around a second. It will only spool faster without the MAFS on there and a leaner mixture at the transition when i put the FAST on it.

 

[Fuelie600]

I wouldn't be the least bit concerned. T-netics builds the BB70Q turbo with the PTE housing. Mine came new this way. As for lag with a BB turbo---what? I can't stop the turbo from spooling. On the foot brake, it used to hit 20 psi. Bolt it on and enjoy. Brian