Yet Another "Which Turbo" Thread - 120 mph Goal

[mgmshar]

My 1987 GN is a full-weight car with a mild build-up (see below). I'm currently running a TA-49 with a Precision .85 turbine housing. With my combo, this turbo spools like crazy - I can easily reach 0 psi at less than half throttle against the converter. Last time I checked, there was some play in the bearings, so I'm thinking it's time for a rebuild or replacement.

Best 1/4-mile on this combo was 11.42 @ 119, which I did with 100-octane unleaded. I was running about 25 psi and 23-deg. of timing on those passes. My goal would be to run a similar ET (don't have a cage), but a little more mph (would like to break the 120-mph barrier). At the same time, I would like to maintain as much of the streetability as I can.

My options, I'm thinking, would be as follows:
1. Rebuild the TA-49 - cheapest option, assuming no wheel damage.
2. TA60 - bigger compressor wheel than TA-49, but same exhaust wheel
3. TA51 - same compressor wheel as the TA49, but larger exhaust wheel
4. TA52 - bigger compressor wheel and exhaust wheel than TA-49
5. Something from the new technology (GT wheels, CEA, etc.) - most expensive option

Combo is below:

Air Intake: Tin-Man CAI, CAS-V2, Ported throttle body and plenum, Power Plate

Engine: Completely stock internals (heads are not ported, stock cam)

Fuel: 57-lb injectors, upgraded/hot-wired fuel pump

Exhaust: 3" THDP, test pipe, ATR 2.5" duals

Torque Converter: Mike Ridings lock-up unit, would guess about 2800 RPM stall at 0 psi (give or take a bit). Like I said, spooling the current TA-49 with Precision .85 exhaust housing is no problem at all.

If you propose something from the "new technology", I would appreciate if you can provide a compressor map. I like to look at the data rather than rely on blind faith.

Opinions?

Thanks,

 

[Mr.Spool]

how does the rest of the timeslip look?60ft,330,1/8mph etc.if the car has no bar you are technically finished at the track now being slightly under 11.49.not quite sure about wanting to go 120 since you are already at 119mph you won't feel it,not sure why you would change the combo?you are getting to the end of the road with the 49 although you can drop the et and maybe squeeze a few more mph.cheapest way to go would be to keep the 49 and take weight out of the car.with c16 3500lbs 30psi the 49 turbo has been 10.80's at 125 on a slick and stock motor.

 

[mgmshar]

how does the rest of the timeslip look?60ft,330,1/8mph etc.if the car has no bar you are technically finished at the track now being slightly under 11.49.not quite sure about wanting to go 120 since you are already at 119mph you won't feel it,not sure why you would change the combo?you are getting to the end of the road with the 49 although you can drop the et and maybe squeeze a few more mph.cheapest way to go would be to keep the 49 and take weight out of the car.with c16 3500lbs 30psi the 49 turbo has been 10.80's at 125 on a slick and stock motor.

60-foot time was a 1.59. Can't remember 330' and 1/8-mile, and I don't have the time slip handy (it's buried in a pile). In a nutshell, I know that the TA-49 is pretty much maxed-out (just got done plotting data on the compressor map - it's scary). I'm considering something a little bigger to allow me to make a few more hp without giving up too much streetability.

Thanks,

 

[Jerryl]

60-foot time was a 1.59. Can't remember 330' and 1/8-mile, and I don't have the time slip handy (it's buried in a pile). In a nutshell, I know that the TA-49 is pretty much maxed-out (just got done plotting data on the compressor map - it's scary). I'm considering something a little bigger to allow me to make a few more hp without giving up too much streetability.

Thanks,

What RPM did you cross the line?
What size tires?

 

[mgmshar]

What RPM did you cross the line?
What size tires?

About 5350 RPM with 26-inch tires. It's about time to invest in a new set of slicks, so I can change the tire size.

 

[Jerryl]

About 5350 RPM with 26-inch tires. It's about time to invest in a new set of slicks, so I can change the tire size.

I would get a bigger tire. Much easier and cheaper than retuning the combo.

Alky injection at lower boost (21-22) will easily get it done as well.

 

[mgmshar]

I would get a bigger tire. Much easier and cheaper than retuning the combo.

Alky injection at lower boost (21-22) will easily get it done as well.

Tuning doesn't bother me, since I burn my own chips. New tires and alky may be in the equation in the next year or two, but I'm not sure yet.

Maybe I should ask a simpler question. I have a pretty good understanding of the "old-school" turbos (TA and PT series), but I don't know much about the newer GT-series and PTE CEA series. Within these newer series, which would be the "next step up" from a TA-49? Would compressor maps be available for those?

Thanks,

 

[mgmshar]

Just to expand on my previous post...

The image below with the red dots shows where my turbo (TA-49) is operating during a 1/4-mile pass with 93-octane and no alky (a typical "street" configuration). This as a 108 MPH pass. The large cluster of points is where the turbo was operating after reaching full boost and going through the gears (most of the run). The points are in a pretty good spot - away from the surge line and reasonably efficient.

The image below with the blue dots shows where my turbo is operating during a 1/4-mile pass with 100-octane (my typical "drag strip" configuration). This is a 119 MPH pass. The large cluster of points is where the turbo was operating after reaching full boost and going through the gears (most of the run). The cluster of points is off the map. I would guesstimate that they are between the 60 and 70% efficiency lines, and the turbo was running something like 125,000 RPM. Anyone who is running close to 500-hp through a TA-49 is operating like this.

My goal is to get a turbo whose compressor map goes a little to the right and up of this map. That would put the blue points closer to the efficiency islands, and the red points almost dead on the efficiency islands. The result should be more efficient airflow, and thus hp, potential. Hopefully that makes sense.

 

[bison]

Just to expand on my previous post...

The image below with the red dots shows where my turbo (TA-49) is operating during a 1/4-mile pass with 93-octane and no alky (a typical "street" configuration). This as a 108 MPH pass. The large cluster of points is where the turbo was operating after reaching full boost and going through the gears (most of the run). The points are in a pretty good spot - away from the surge line and reasonably efficient.

The image below with the blue dots shows where my turbo is operating during a 1/4-mile pass with 100-octane (my typical "drag strip" configuration). This is a 119 MPH pass. The large cluster of points is where the turbo was operating after reaching full boost and going through the gears (most of the run). The cluster of points is off the map. I would guesstimate that they are between the 60 and 70% efficiency lines, and the turbo was running something like 125,000 RPM. Anyone who is running close to 500-hp through a TA-49 is operating like this.

My goal is to get a turbo whose compressor map goes a little to the right and up of this map. That would put the blue points closer to the efficiency islands, and the red points almost dead on the efficiency islands. The result should be more efficient airflow, and thus hp, potential. Hopefully that makes sense.

View attachment 156394

View attachment 156395

60-1. You need to increase the airflow through the engine to really see a gain with more turbo though. You would see about 100whp with a 60-1, heads, and 206/206 roller @25psi if the converter could couple it. Increasing airflow will move you down and to the right on the map. The 60-1 hits hard around 55lbs/minute 2.2:1

 

[Jerryl]

Tuning doesn't bother me, since I burn my own chips. New tires and alky may be in the equation in the next year or two, but I'm not sure yet. . .

I really should refrain from "giving advice” about something I have never done . (No pun intended) I wanted to say 60-1 based on what Bison has done, but I would listen to Bison and go from there. Good luck, and let us kow what you decide.

 

[mgmshar]

I already plotted the points against the 60-1 (see below) - this would be what I would see with a TA-60. The points are definitely too far to the left. I wonder if going to a larger exhaust wheel (like TA-52 with T350 turbine) would allow enough additional airflow through the engine to move them significantly to the right? A cam and heads are not in the cards in the near future.

Second question - how much does it cost to get a turbo rebuilt (bearings and balance of rotating assembly) assuming the wheels aren't damaged?

Thanks,

 

[JT'sV6]

Lock the converter.

 

[mgmshar]

Lock the converter.

I already am locking the converter - after the 2-3 shift is completed.

 

[Mr.Spool]

when you change the ex wheel your stall requirements will also need to change.i wouldnt worry about the map so much,my old 49 combo ran 11 teens for years that way.never hurt it and the turbo is running strong on another car right now.i think you could drop the 60ft, take some weight out and go a little faster,a taller tire will have more rollout and take the hit better off the line.i went 1.55 60ft on a stock motor with a mild port head and a ta49 on a 275 60 15 drag radial. the next step up in turbo will require the supporting mods that bison suggested,and the combo will need to be adjusted and retuned.you have a good running car there may want to keep it where its at.if you need a turbo rec,62/65 or 62/62 or 61/ptrim with a tight ex housing with heads/cam and a smaller dia converter 3200 stall,but like i said thats alot of stuff for the need for 120mph.

 

[mgmshar]

Thanks to everyone for their recommendations. I do appreciate them. I think I'm going to stick with my TA-49 and just get it rebuilt somewhere. It seems like the "next step up" in a turbo is really going to need a bigger cam, heads, etc. If I'm going to go that far, I'll just build a second engine when I get the inclination and do everything right from scratch. Besides, if I had grown a pair and put C16 in the car, I could have run a lot more timing, and I probably would have gotten my 120mph pass on that TA-49...

Instead of putting the money on a new turbo, I'll probably upgrade my ten-year-old slicks to a 28-inch diameter.

Thanks again. Hopefully the turbo maps I put up will help somebody down the road.

 

[mgmshar]

when you change the ex wheel your stall requirements will also need to change.i wouldnt worry about the map so much,my old 49 combo ran 11 teens for years that way.never hurt it and the turbo is running strong on another car right now.i think you could drop the 60ft, take some weight out and go a little faster,a taller tire will have more rollout and take the hit better off the line.i went 1.55 60ft on a stock motor with a mild port head and a ta49 on a 275 60 15 drag radial. the next step up in turbo will require the supporting mods that bison suggested,and the combo will need to be adjusted and retuned.you have a good running car there may want to keep it where its at.if you need a turbo rec,62/65 or 62/62 or 61/ptrim with a tight ex housing with heads/cam and a smaller dia converter 3200 stall,but like i said thats alot of stuff for the need for 120mph.

Mr. Spool,

I would love to know how you went 1.55 on a 275/60-R15 drag radial. I have a set of Nitto Drag Radials, exactly that size, mounted on a set of GN rims that I had widened to 8-inches. I have the ATR sway bar, tubular upper and lower control arms with polygraphite bushings, and air bags. I know I couldn't even come close to that time on the Nittos, and it would take a perfect track for me to get that on my 26X9 slicks. Any tips?

Thanks,

 

[bison]

I already plotted the points against the 60-1 (see below) - this would be what I would see with a TA-60. The points are definitely too far to the left. I wonder if going to a larger exhaust wheel (like TA-52 with T350 turbine) would allow enough additional airflow through the engine to move them significantly to the right? A cam and heads are not in the cards in the near future.

Second question - how much does it cost to get a turbo rebuilt (bearings and balance of rotating assembly) assuming the wheels aren't damaged?

Thanks,

View attachment 156396

View attachment 156397

The t350 would show power with a 60-1 but the 60 trim is about done if you're looking for 120mph.

 

[Mr.Spool]

mike,timing was at 26 in 1st gear,car had a 4.10 rear and a 3200 stall 10.5 protorque.actually went 1.58 on the stock suspention with both sway bars in and bfg drag radials, that was before the softer stuff came out.not sure which nitto you are running but the nt05r is comparable to the mt street radials,the 555r is a harder compound.track prep wasnt great either on my passes.the 1.55 was the sway bar out, metco uppers and lowers.

 

[we4Mateo]

Mr. Spool,

I would love to know how you went 1.55 on a 275/60-R15 drag radial. I have a set of Nitto Drag Radials, exactly that size, mounted on a set of GN rims that I had widened to 8-inches. I have the ATR sway bar, tubular upper and lower control arms with polygraphite bushings, and air bags. I know I couldn't even come close to that time on the Nittos, and it would take a perfect track for me to get that on my 26X9 slicks. Any tips?

Thanks,

I go 1.6x 60's a lot with just a 255/60/15 tire w/ a best of 1.61. That's both sway bars in and launching on the spoolup around 4psi or so. For me it was the stall that accomplished this. Hope this helps.