Please explain "3.0-3.2 inch tangent on the exhaust housing"

[KWIKR 1]

Due to the design of the sbc TT kit I have I was told I can only use turbos with the following dimension : as quoted to me : "It must be a 3.0-3.2 inch tangent on the exhaust housing. If you lay the exhaust housing flat on the v-band flange the edge of the inlet flange should be touching the table too."

Please explain to me where or what the hell is the 3.0" - 3.2" tangent that he's talking about ??? I understand the other part about the v-band flange and inlet flange . Many thanks !

 

[RUQWKNF]

Very odd indeed. The only thing I can gather from the 3.0 - 3.2 tangent would be the size of the downpipes that come with the kit are designed to work with 3" to 3.2" discharge T4 turbine housings. Tangent = tangential?
T4 housings that are sold today are of the Tangential design. This means that the centerline of the T4 inlet flange is not inline with the centerline of the rotating assembly. The other style T4 turbine housing that were made, were an On Center design. Those T4 housings had the centerline of the T4 inlet flange inline with the centerline of the rotating assembly. Hence the on center name.

With regards to the flange info, if you turn the turbo so that the turbine housing downpipe flange is resting flush on a table, (basically having the compressor side pointing skyward) the edge of the T4 inlet flange should be on the same plane as the flatness of the downpipe flange. This is probably due to the design of the downpipes and clearance issues. Most all T4 housings that are out there, including the ones that we make, are not flush in this spot. The T4 inlet flange slightly sticks our further from the downpipe v-band flange. Exactly how much varies from turbo to turbo.

I would want a lot better clarification from that kit maker as to why that is so important before I purchased a complete kit. As what has been said is very vague at best. I can understand about the Tangent deal, as the turbo picture you included is of a turbonetics Tangential T4 turbine housing equipped turbo.

Hope some of this helps.

Patrick

 

[KWIKR 1]

Very odd indeed. The only thing I can gather from the 3.0 - 3.2 tangent would be the size of the downpipes that come with the kit are designed to work with 3" to 3.2" discharge T4 turbine housings. Tangent = tangential?
T4 housings that are sold today are of the Tangential design. This means that the centerline of the T4 inlet flange is not inline with the centerline of the rotating assembly. The other style T4 turbine housing that were made, were an On Center design. Those T4 housings had the centerline of the T4 inlet flange inline with the centerline of the rotating assembly. Hence the on center name.

With regards to the flange info, if you turn the turbo so that the turbine housing downpipe flange is resting flush on a table, (basically having the compressor side pointing skyward) the edge of the T4 inlet flange should be on the same plane as the flatness of the downpipe flange. This is probably due to the design of the downpipes and clearance issues. Most all T4 housings that are out there, including the ones that we make, are not flush in this spot. The T4 inlet flange slightly sticks our further from the downpipe v-band flange. Exactly how much varies from turbo to turbo.

I would want a lot better clarification from that kit maker as to why that is so important before I purchased a complete kit. As what has been said is very vague at best. I can understand about the Tangent deal, as the turbo picture you included is of a turbonetics Tangential T4 turbine housing equipped turbo.

Hope some of this helps.

Patrick

Thanks Patrick . maybe if you go to the site and look at the kit it may make more sense as to what he's talking about . because I don't have a clue .

The kit is at : Company | Wrenchrat

Twin turbo kit - Team Camaro Tech few other close up pics of it .

 

[RUQWKNF]

I see what's going on now.
The reason they are mentioning the 3.0 - 3.2 is probably due to the fact of clearance from the turbine housing to the valve cover. The way the downpipe feeds through the primary tubes would be totally screwed up if you tried to use a larger turbo than a standard T4 Tangential style turbine housing equipped turbo.

Some of the larger mid frame turbos, like our HP8884, feature a much larger T4 turbine housing and a much larger compressor cover that would never work with this kit. But from the looks of that design, our largest standard T4 turbo that we offer, the PT76HPS, should fit just fine and provide a lot more hp capability than the ones listed on their site.

I know, I sure would like to see an intercooler on that setup though. Huge increase in power vs non intercooled. It's all about clearances. Those are standard T4 Tangential t-netics turbine housings. Same outside dimensions that our T4 Tangential turbine housings have.
Hope this helps.

Patrick

 

[KWIKR 1]

I see what's going on now.
The reason they are mentioning the 3.0 - 3.2 is probably due to the fact of clearance from the turbine housing to the valve cover. The way the downpipe feeds through the primary tubes would be totally screwed up if you tried to use a larger turbo than a standard T4 Tangential style turbine housing equipped turbo.

Some of the larger mid frame turbos, like our HP8884, feature a much larger T4 turbine housing and a much larger compressor cover that would never work with this kit. But from the looks of that design, our largest standard T4 turbo that we offer, the PT76HPS, should fit just fine and provide a lot more hp capability than the ones listed on their site.

I know, I sure would like to see an intercooler on that setup though. Huge increase in power vs non intercooled. It's all about clearances. Those are standard T4 Tangential t-netics turbine housings. Same outside dimensions that our T4 Tangential turbine housings have.
Hope this helps.

Patrick

Thanks....for figuring it out . I will be using a IC . . so...3.0-3.2 is what actual measurement ? so any standard T4 Tangential style turbine housing equipped turbo will fit ? why does the v-band flange have be even with the inlet flange? I can't see that being a issue , it would just move the DP a little forward or back .. a PT76HPS is a little crazy big for my needs . what do you have in a 62-1 that would fit , non BB and BB ? would a Precision SC6265SP fit ?

like this one : http://cgi.ebay.ca/Precision-SC6265...r_Truck_Parts_Accessories&hash=item518d6d4c85

 

[RUQWKNF]

Yes, those 6265 turbos would be capable of supporting 900-1200 flywheel hp pretty easily on that setup. One thing to remember though, those are journal bearing so you will be torque converter dependent with those turbos on a 350-400ci V8. T4 .68 A/R housings would be the smallest I would go with on them for that combination. If you went with the Air Cooled DBB version, you could get away with T4 .81 A/R sized turbine housings and have more flow potential and more HP potential. Due to the reduction in back pressure from the larger turbine housing.

HTH

Patrick

 

[KWIKR 1]

Yes, those 6265 turbos would be capable of supporting 900-1200 flywheel hp pretty easily on that setup. One thing to remember though, those are journal bearing so you will be torque converter dependent with those turbos on a 350-400ci V8. T4 .68 A/R housings would be the smallest I would go with on them for that combination. If you went with the Air Cooled DBB version, you could get away with T4 .81 A/R sized turbine housings and have more flow potential and more HP potential. Due to the reduction in back pressure from the larger turbine housing.

HTH

Patrick

will do...thanks Patrick . In relation to the attached diagram , what dimension would be the 3.0"-3.2" reference ?

 

[KWIKR 1]

got ahold of the guy who designed this system . The 3.0"- 3.2" "tangent" dimension that he was referring about . Is the measurement from the face of the the inlet flange to the center of the exhaust housing . in respect to the diagram that I posted it would be the 2.93" measurement . the reason for it is , any more than 3.2" the downpipe will hit the primary tubes . does make sense when you look at the picture of header/DP . would of been little easier to figure out if he just said that the first time , rather than referring to it as tangent dimension .
Many thanks Patrick for helping me with this and your suggestions .