Turbo advice

[Zmanco]

I'm just about ready to buy my turbo and need some advice.

 

Recap:

L28et bottom end stock

P90 shaved .080", port matched, unshrouded valves, CR = 8.4

MSA Stage II turbo cam

 

I'm currently running a N/A with 10.3 CR and a cam that makes power 3500 - 6500 and my goal is to more or less maintain the same power band, but obviously make more power, around 275 whp. Since I'm running a 4.11 diff with ZX 5 speed, I'm not too worried about making boost at low rpms - I don't have a lot of torque down low right now and I'm fine with that.

 

Based on dozens of threads I've read here along with my own calculations (I'm at 6200 feet) it seems like the T3/T4OE .50 trim is a great choice.

http://www.mygen.com/users/dbruce/myz31/TurboMaps/L28ET%20Engine%20Air%20Flow%20and%20Turbo%20Compressor%20Maps.htm

 

However, given I'm using a stage II cam, I'm wondering what the best choice is for the turbine wheel. Should I go with a stage 3 or 5? What are the tradeoffs of each with that cam? From what I've read, it will spool faster with the stage 3, but the stage 5 will breath better at high revs. Is that about right?

 

Also, what is the recommended Trim and A/R for the turbine with my cam? It looks like most people are staying with the stock T3 housing (0.63 A/R?), but I can't tell what Trim they're running.

[wigenOut-S30]

Sounds like it is a nice little setup. From what I have found a stage 5-P trim exhaust wheel in a .63 exhaust housing is the way to go. It will spool just as well as the stage 3 but flow a good bit more.

[jc052685]

I am running a .63 stage 5 hotside with a 60 series compressor and I have 18psi by 3400rpm.

[Zmanco]

I am running a .63 stage 5 hotside with a 60 series compressor and I have 18psi by 3400rpm.

So it sounds like a stage 5 turbine is the way to go with a bigger cam? Anyone else have any experience they can share?

[Brad-ManQ45]

Match the AR for the exhaust and the trim of the turbine to the rev range of the cam.

 

Stock cam needs to keep stock/clipped at most Stage 3 turbine and stock AR.

 

Bigger cams, moving powerband up the rev range would require larger (more open/larger outlet/higher trim # - Stage 3 or 5) and possibly larger AR housing.

[Pyro]

I run the msa turbo stage 1 cam with 7.4:1 cr and a T3 stage 5 turbine with a T04B-H3 compressor.

 

Starts to build boost at 3000 and makes full boost by 3500 and pulls hard to 6500. Drives nice on the highway as I can drive it at 80mph without boosting (10 inhg vacuum). The stock turbine was running at 0 inhg at 80 mph (almost boosting). Plus the bigger turbine hits much softer which makes it more controllable, unlike the stock turbine which is on or off.

 

My compressor would surge if boost was made any sooner. Not the best compressor but it fits without a spacer. The t04E-50 is the way to go but requires a 1/2 inch spacer between the turbine and manifold.

 

Yes, Brad is correct. match the cam to the turbine. a stock cam runs nicely with the stock turbine. A bigger cam does well with a free flow turbine. It is all about cam overlap (reversion) and pressure difference between the intake and exhaust manifold. Small turbines create lots of exhaust manifold pressure which doesn't tolerate any valve overlap. Great for low rpm torque.

[Zmanco]

So for a stage II MSA cam, should I go up on the compressor trim? The charts for the T3/4OE .50 trim fit my goals well (make good torque in the 3500 to 6500 rpm range) and I haven't been able to find one for other trims (such as .57).

 

How would larger trim numbers change the charts?

 

Also, can someone explain what changes with the turbine wheel as the stage number goes up? Is this just another way of measuring the trim of the turbine wheel?

[jeffp]

I ran the TO4E turbo I think it was a .50 trim. I had the stage 5 exhaust turbine wheel.

The cam 266 duration, 112 lobe centers 480 lift intake open 21 BTDC clises 66 AABDC and the same on the exhaust (strait up grind) overlap of 48 I believe.

Stock exhaust manifold and waste gate. 8.5 : 1 compression.

I wouold be fully spooled by 3K and boy what a change from no turbo boost to boosted, almost uncontrolable. I ran the car to 7K and I was doing about 475Hp with that setup.

 

Go for the TO4E a good 3" exhaust and stock wastegate with boost controller. That is a very good setup.

You guys mention stage cams like that is supose to mean anything to anyone. List the cam specifications and that will be much better.

Realistically, you could run a STOCK cam and get very good results to 450-500Hp or so.

[jgkurz]

I ran the TO4E turbo I think it was a .50 trim. I had the stage 5 exhaust turbine wheel.

The cam 266 duration, 112 lobe centers 480 lift intake open 21 BTDC clises 66 AABDC and the same on the exhaust (strait up grind) overlap of 48 I believe.

Stock exhaust manifold and waste gate. 8.5 : 1 compression.

I wouold be fully spooled by 3K and boy what a change from no turbo boost to boosted, almost uncontrolable. I ran the car to 7K and I was doing about 475Hp with that setup.

 

Go for the TO4E a good 3" exhaust and stock wastegate with boost controller. That is a very good setup.

You guys mention stage cams like that is supose to mean anything to anyone. List the cam specifications and that will be much better.

Realistically, you could run a STOCK cam and get very good results to 450-500Hp or so.

 

I agree with the T04E with a 50 trim compressor. Peak flow occurs around a pressure ratio of ~2.5 or 23psi. This translates to ~47.5lb/min which is roughly 475hp. For the turbine, use a stage 3 or stage 5 turbine wheel. Stage 3 will spool faster but supports less HP. Make sure to use a .63 turbine housing. 3" exhaust is a MUST in my experienced opinion. If you are using a Nissan L28ET exhaust manifold you will need a .50 AR compressor housing if no spacer is used. For reference, .60 AR compressor housing is usually preferred with the T04E turbos but not critical. Hope that helps.

 

T04E Map:

http://majesticturbo.com/30375.html

[Zmanco]

Thanks everyone for the feedback - this is just what I was hoping for.

 

FYI, the MSA stage II turbo cam is a Schneider cam with the following specs:

Intake Duration (gross): 270

Exhaust Duration (gross): 260

Intake Duration (.050”): 230

Exhaust Duration (.050”): 220

Intake Valve Lift*: .460"

Exhaust Valve Lift*: .460"

Lobe Separation: 114

 

I'm torn between a stage III and stage IV turbine wheel but am leaning towards the stage III even though it will limit my power at the top end. Remember, my goal is "only" ~275 whp and most of my driving is on the street. I have a 4.11 diff so like turning revs...

 

Now I'm looking for a good place to buy the turbo. I found a shop in AR called G-Pop Shop and spoke with him for a while. I have a near zero miles stock T3 which he recommends building into the hybrid, but that is around $700 (all Garrett parts though). I'm wondering if I should be looking at buying a new Precision Turbo (made by Garrett?) for only a little more and then sell the T3?

 

Either way, any suggestions for where to buy the turbo? I'm in Colorado and would love to buy local if I could.

 

Edit: what do you think about a Turbonetics version of a T3/T4O3?

[wigenOut-S30]

I ran the TO4E turbo I think it was a .50 trim. I had the stage 5 exhaust turbine wheel.

The cam 266 duration, 112 lobe centers 480 lift intake open 21 BTDC clises 66 AABDC and the same on the exhaust (strait up grind) overlap of 48 I believe.

Stock exhaust manifold and waste gate. 8.5 : 1 compression.

I wouold be fully spooled by 3K and boy what a change from no turbo boost to boosted, almost uncontrolable. I ran the car to 7K and I was doing about 475Hp with that setup.

 

Go for the TO4E a good 3" exhaust and stock wastegate with boost controller. That is a very good setup.

You guys mention stage cams like that is supose to mean anything to anyone. List the cam specifications and that will be much better.

Realistically, you could run a STOCK cam and get very good results to 450-500Hp or so.

 

Hey Jeff, What boost level were you running with this setup?

Thanks

[Zmanco]

For those of you who went with at T3/T4OE, how thick does the spacer between the manifold and the turbine housing need to be? Would 3/8" allow the compressor to clear?

[wigenOut-S30]

Im running a 1/2 spacer

[jgkurz]

For those of you who went with at T3/T4OE, how thick does the spacer between the manifold and the turbine housing need to be? Would 3/8" allow the compressor to clear?

 

Remember, you only need a spacer if you have a compressor housing larger than .50 AR. The larger .60 housing is actually better if you plan to use a spacer.

[Zmanco]

Remember, you only need a spacer if you have a compressor housing larger than .50 AR.

jgkurz, given I'm planning on the .50 AR, do I still need the spacer? From what I've read here I think I do, but I'd be glad to leave it off if it's not required.

[jgkurz]

jgkurz, given I'm planning on the .50 AR, do I still need the spacer? From what I've read here I think I do, but I'd be glad to leave it off if it's not required.

 

All I know is that my turbo has a .50 compressor housing and I don't have a spacer. Not sure if it's from a T04B or T04E. It may not matter. Another issue is you will need to re-route your PCV and possibly wrap your exhaust manifold since the compessor only has about 3/16 clearance with a .50 AR housing.

[Zmanco]

Thanks John, I suspect you have the TO4B - I understand the diameter is a bit smaller and will fit without a spacer.

 

I currently have a N/A intake manifold that is port matched to my P90 head so was hoping to use that. But I also have a turbo manifold which I believe solves the PCV relocation issue. Once I have the turbo I'll mock it up and decide which one to use.

[Soundmasterg]

Remember, you only need a spacer if you have a compressor housing larger than .50 AR. The larger .60 housing is actually better if you plan to use a spacer.

 

How do you tell which housing you have? I bought a rebuilt T3/T04E at the Canby show and I don't have much info on it besides that the exhaust is a .82 or something like that. Still trying to figure out what all these numbers and A/R ratios and trim stuff means and how my turbo fits into the equation.

 

Thanks,

 

Greg

[jgkurz]

How do you tell which housing you have? I bought a rebuilt T3/T04E at the Canby show and I don't have much info on it besides that the exhaust is a .82 or something like that. Still trying to figure out what all these numbers and A/R ratios and trim stuff means and how my turbo fits into the equation.

 

Thanks,

 

Greg

 

It's not easy. Look at the casting of both the compressor and turbine housings. There should be some number(s) inscribed on the side indicating A/R. BTW, a .82 A/R turbine housing is the max I'd use on a street L28 but only if I was willing to sacrifice spool for peak HP. Personally I prefer a .63 A/R turbine.

[Soundmasterg]

It's not easy. Look at the casting of both the compressor and turbine housings. There should be some number(s) inscribed on the side indicating A/R. BTW, a .82 A/R turbine housing is the max I'd use on a street L28 but only if I was willing to sacrifice spool for peak HP. Personally I prefer a .63 A/R turbine.

 

Thanks,

 

I'll have to see if I can spot any numbers on it. I got this one because the price was good and Hugh talked me into it, but I'm not opposed to selling it and getting a .63 or something more correct. I haven't built the engine yet so I can tailor it to whichever turbo I end up with. Since you're local to me, maybe you might be able to look at this turbo and tell me what it is that I have one of these days?

 

Greg