Help me pick a turbo (Non Miata)
 

I’m trying to pick a cheap turbo for another vehicle out team is bringing to the GRM challenge. Time and money have kind of changed our plans and I’m now looking at cheap ebay T3/T4 turbos. This is not going on a Miata. The engine is a 4.0L that makes peak power at 4750 RPMs with a redline of 5250. Our goal is about 325 hp and I’m thinking that 10 psi on a 50 or 57 trim T3/T4 should work. Now looking at the 2 compressor maps the 50 trim looks like a more efficient turbo even though it’s smaller. Here are 2 images from squirrel performance to give you an idea. The lines on the maps might be off a little since I was only trying to get a rough idea.

http://www.squirrelpf.com/turbocalc/...&product_id=57

http://www.squirrelpf.com/turbocalc/...&product_id=60

Now a 60 trim would be a better fit but those turbos go for more money. The $130 price for the others is a better fit to our budget. Now I just wanted to know if the 50 trim is a better fit then the larger 57 or am I seeing things.

Next question, do you think I can get away with running an internal wastegate? An external would cost us more money.

a 4.0l? hmmm the old jeep i used to have certainly comes to mind lol. something much larger then a 50 trim would be better. go for something comparable to the prescision 6057

well either will work, your exhaust housing will make a big difference, the graphs seem weird for a 50 better(over all) then the 57.

Either will most likely start to run out of power above 5k with a 4L. I know 50tirms on a 2L will start to just lose breath above 8K. I would try and find the best budget 50/57 unless you can find a good used 60 trim

5k is pretty much our redline and we wont be going past that. It looks like we really can't go wrong with either turbo for our goals.