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L28 NA with a GT3071?


redfogo

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I have a GT3071 from a past build, and I recently picked up a 280z. I know the L28 N/A can't handle alot of boost but the most cost effective turbo kit would be turboing my L28 NA with the GT3071. I figure get a manifold and a Megasquirt and run things on E85 for added safty.

 

Or I could wait around and look for a L28ET, but they are getting hard to find as it is!

 

Last option is a RB25 I guess they have come down in price, but I'm not sure if this will be worth swaping since I really just want a fun car to drive with a bit of boost nothing wild and RB25 still seems like it will cost alot to finish the swap.

 

Thoughts?

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That seems like the turbo will be too much for just an NA block with flat tops or a minor dish. Cost effective would be to sell the turbo, pickup an L28et manifold, a replacement T3, a crank trigger wheel, HES mount, and LS coils, and drill the pan for a bung and T off the oil pressure source if a bit of boost is all you want.

 

Unless you have a T3 hot side, you are going to have to run an adapter/spacer and there isn't much room in there to run one. I guess alternatively you can have one welded, but that means you have to get a dump pipe made up and custom exhaust work.

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I'm running a GT3071  with a  T3 .63AR on my L28ET. Not sure what your hotside is, but I imagine we're fairly similar in size. What AR exhaust housing do you have? I find the turbo to work great with my engine. Boost starts to build around 2500 and I hit the 8PSI i'm currently running by 3000-3200. I'm still tuning so haven't upped the boost yet, but I think it feels great even at just 8PSI. Personally I'd go for it, especially if you're capable of the fab work needed. 

Edited by calpoly-z
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GRT-TBO-020    Garrett GT3071R Turbo Ball Bearing Turbo       
               Turbin_AR: 63
               Select_Turbine_Housing_Style: T3_T4_Style_Dropin_Replacement
               Compressor_Hsg_Style: 300inchCompacdtHousing

 

The above is what I'm running. I bought a compact cold side, so no spacer was needed to prevent hitting the stock exhaust manifold, . Running the "utimate wastegate" that ATP sells as well. No issues with boost creep. I did a lot of research and looking at compressor maps before buying a turbo and I thought this turbo fit the L28 quite well. And now after driving it a bit I'm still very pleased with my choice. 

 

If you're worried about compression being too high, just throw a thick headgasket on to drop the static CR down a bit. 

 

I can't comment on the E85. I'm stuck running 91 octane out here in the West Texas desert. 
 

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I'm running a GT3071  with a  T3 .63AR on my L28ET. Not sure what your hotside is, but I imagine we're fairly similar in size. What AR exhaust housing do you have? I find the turbo to work great with my engine. Boost starts to build around 2500 and I hit the 8PSI i'm currently running by 3000-3200. I'm still tuning so haven't upped the boost yet, but I think it feels great even at just 8PSI. Personally I'd go for it, especially if you're capable of the fab work needed.

 

Yep I have a .63 AR and T3 ford style exhaust outlet. It seems to be like l28et have lower compression then needed I have seen plenty of people run 8:3 like the l28 has on other engine but most of those of DOHC set ups so I wasn't sure.

 

Calpoly-z sounds like we have the same turbo. Is yours on a l28? Or l28et?

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I'm running an L28ET with dished pistons overbored 0.030", and a slightly shaved P90. Compression is probably in the high 7's. If your L28 is around 8.3CR then I think you'll be good. Run conservative timing in boost and keep boost pressures reasonable and enjoy! 

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Keep your thick headgasket in the box  and just keep your boost reasonable.

Adding that thick gasket is a stopgap that just kills quench and makes the thing a detonation-prone monster.

8.3 or 8.5 will handle 10-12 psi from the stock turbo but that's a lot different than 10-12psi from a GT3071, you're better off getting the head reworked with pistons matching your closed-combustion chamber and ported cammed head.

 

You can run some higher boost then, and make great power. 

 

Or keep it all stock up top and start cranking in the boost and  start detonating, blowing the spark kernel out, etc....

 

Use the flow from the turbo, not necessarily the pressure. It makes everybody's life easier in the long run!

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E85 is another item to ditch that thick gasket. I ran 10-12 psi unintercooled on 8.5 with just gas gas... E85 is better in that regard, like race gas.

 

Almost any N/A engine is good for 10PSI out the gate. That's where I start. The stock wastegate is lower than that...but you aren't using a stock turbo so problem solved!

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