If EFR budget...
 

A two part query for you:

If you had the budget for a efr 7163 and a chassis waiting on power would you consider anything else (gtx, comp triple ball bearing, ect)?

Why?

I have the chassis, powerplant to support, and have done my research but need to get a new Mani built to insert said turbo and am looking for some other opinions. Thanks guys.

Not really. Maybe re-evaluate your power goals and decide whether you really want/need 500whp, and if you can live with 450, look at a 6758 to improve low-end power.

Although I agree that making sure 500rwhp is something you are actually looking for I would like to add that the testing I have seen of the two turbo's back to back show that the 7163 out performs the 6758 in almost every way because it is a gen 2 design.

EDIT: I also understand that this is a full throttle run and does not provide part throttle or transient response data but my throttle only has 2 positions anyway :party:

https://www.miataturbo.net/attachmen...ine=1404325846

EDIT 2: Not a built bp but the behavioral characteristics are still relevant.

Until there is an acceptable transmission solution I can't really recommend anything except 6258.

So the goal is 300 HP with low boost but also to have the ability to run a higher pressure and not be limited by the turbo or fuel. I feel I have the supporting items to do that before going with a new engine management system and a vvt head (these are the next steps for me).

get the 6258

I made you a chart
https://www.miataturbo.net/attachmen...1&d=1404398699

Gooby plz!

wish I could probab that 10 more times :bowrofl:

Get a 6258.

Along these lines... I already have a Precision 4828 which is supposedly a potato with some better parts. It is on a BEGI cast manifold. Would it make sense to move the precision turbo over to an EFR compatable manifold and fab a downpipe until I can afford to build the motor (hopefully get better spool out of it) or should I just hold off and do the EFR at the same time as the manifold/downpipe? I am at about 230whp now but I feel like I am not hitting 10psi boost until 4,300 rpm or so.

(my spool data:)
https://www.miataturbo.net/diy-turbo...2/#post1140285

Current downpipe is BEGI non-divorced gases pipe that exits to 2.5" and it continues 2.5" to the muffler at which point it exits at 3". I am holding off upgrading the mid-pipe until I also do the downpipe...

If my goal is to improve spool and reduce the amount of parts bought twice, where is the smart money?

Given the following future upgrades: build engine with forged rods, EFR 6758 or 6258, EFR compatable manfold, 3" turbo to tailpipe.

Also, consider that the block is stock for now.

if you want spool your money needs to go to tubular hotside parts and a proper 3" tbe
I'm also assuming you're already running ebc and the wga arm is tight. (forgot your mod list already)

^ Yes.

To isolate one question I asked above, can I mount my current turbo on a tubular manifold designed for an EFR? Obviously it would be a different downpipe than an EFR but if I am going to replace something, i'd rather it be the downpipe. Heck, I might even be able to modify the downpipe to make it work, but then that might be almost as much money as a brand new one?

Sounds like an efr it is. Thanks guys

One point here,

Never use a dynapack dyno to show differences in spool up of different turbos. You can program the ramp rate of the dynapack which allows you to set it to increase RPM's from 2000 to 4000 very slowly, and this will tend to make a large turbo spool at a much lower RPM than it would if RPM's increased at a faster rate. I'm not sure if other load cell dyno's can do this but I know that the dynapack can.

Keith

what is the availability like on these things now?

Stop using this graph please. The 6758 had the TGVs stuck closed on a bank and the 7163 was the pre-release version with the not as good compressor wheel.

This.

What's wrong with a TII drivetrain?

Gearing.