Pat's Ebay Turbo Compound Boost Build
 

This will be a compound setup for now, turbo in the rear of the car under the A/C condenser. May end up bypassing the supercharger once it spools, but not for now as that adds complexity for valves and crap. Also plan to just unhook the supercharger at some point just to see how it spools without the blower at all. Probably be extremely laggy without the SC helping it spool though.

Goal is to complete the entire setup for under 1,500 dollars. I'm around 1,100 in it so far and need to order some fuel system stuff.

Always wanted to try this for a long time, so doing it now since the Whipple by itself isn't fast enough and there isn't much I can do to really get a lot more out of it. With the SC after 20 PSI the SC is killing my power as Eric suggested more than once. So I'll be putting a bigger pulley on the SC so it only runs around 20 PSI, and the turbo will pickup the rest.

Air flow path will be:
Air filter, turbo, 2.25" pipe to the front, Whipple, Intercooler, Engine.

Turbo:
Ebay GT45, 68.7mm inducer, 97.8mm exducer, T4 Turbine 1.05 AR twin scroll.

Will be using engine oil to lube the turbo and a scavenger pump to push oil back to the motor. Ebay BOV/60mm wastegate. No intercooler on the turbo for now, gonna see how it does and go from there.

Not sure how much boost/power I'll run, going to get it built and run 5 PSI from the turbo at first. With compounding, that will be about 32 PSI at the motor once I put the 2.75" pulley back on the SC. Probably end up around 40-45 at the motor once the fuel system can keep up but who knows.

Hoping it hits full boost by 4,000-5,000 and rev it to 8,000 for a 3-4K powerband. Got a feeling it will be closer to 5,000 but we will see.

For those that will ask, I'm hoping this setup works ok, and I'll sell the EFR to help cover most of the cost of the compound build.

As for why? I've always wanted to try compounding, and always wanted to try an ebay turbo.

Not much to show, but the turbo showed up today!

EFR 7670, Garrett GT3271, and piston/rod for reference.

https://www.miataturbo.net/attachmen...ine=1454194839

https://www.miataturbo.net/attachmen...ine=1454194839

https://www.miataturbo.net/attachmen...ine=1454194839

https://www.miataturbo.net/attachmen...ine=1454194839

https://www.miataturbo.net/attachmen...ine=1454194839

Well then....

In for soon to be sequentially-compounding turbo feeding supercharger running on c16. (I'd gather that the trans will shatter at take off at this point)

OOH, OR MAYBE YOU CAN USE THE QUICKTIME BELLHOUSING.........

This seems like a terrible idea to me, can't wait to see how it turns out. Keep us updated, I'd really like to see it actually work.

Trans solution? Get a powerglide.

Why a ebay turbo over something a little more proven but still cheap like a used turbo from PTEs site..normaly 6766s are on there rebuilt with a warranty for around $700. I also dont see a turbo of that size from ebay spooling on a 1.8L fully by 5,000 even with the supercharger helping it along.


You also have to remember on a turbo of that size 5 psi will mean absolutely nothing for power. For example on my 68mm turbo on my 2.5L motor it made only 580whp at 28psi..and from there finally woke up and stopped looking like a disappointment from 28psi on to 36 it was averaging 25ish whp per psi and what was with a nice billet wheel/race cover on a well tested and developed turbo.

I think you would see much better spool/response from a nice 62mm efr or a nice borg based unit like a bullseye.


On another note are you going to by pass the supercharger after a certain point or are you going to ram the air through the supercharger?
What are you going to be doing about fueling? I am struggling with my build fuel wise right now i do not want to spend $2-3k on a surge tank setup with a big external from fuel lab or other xx company like i did with my sti but i also do not want to shove two wally460s in the tank and just Y them together and pray that works :s.

Not sure yet, I have 2 6 speeds though to think about it.

This turbo was 200 SHIPPED. Ebay special. Just want to see what I can do on a budget. I know it's cheap/crapy/why didn't you spend 5x more for something better. There is no sane reason to do this, it's for fun.

As for spool, don't know yet but target turbo boost will be 5 PSI from the turbo starting out. I think it will do that by 5K with the SC shoving 15-17 PSI into a 1.9L VVT motor.

Already answered the bypass part in post 1 since I knew that would be a common question.

I have a Walbro 450 and Walbro 255HP in the car now with ID 1000's. Going to drop the base pressure back down some and run a couple nozzles to up the fuel. Probably size the nozzles around 60% of my injector size and stage them in. Will do twin 450's if fuel pressure can't hold, I'm logging fuel pressure already.

Can you please at least get a dyno before starting? Just for a somewhat controlled a/b result that isn't virtual dyno..............

No, just going to build the new setup. It's around 350whp/300wtq now with the whipple. A 350whp turbo car would be faster since they usually have 350wtq too. I drag race the car every weekend, so I know what it runs now, and I'll know what it runs when the turbo is on. If it goes faster in the 1/8th, then it works better than the whipple.

:bowrofl:

This is Pat's version of avoiding complexity! Love it. Sub'd. Gotta' see this.

Haha, yeah... In all honesty it looks like it's going to be fairly easy to fab all this up. I think the worst part will be fabbing a pipe to get to the front without affecting my ground clearance.

Going to get started now, got some work I can do while I wait on parts to arrive.

Have you ever actually tuned for MBT with the blower?

--Ian

I'm fairly confident I would die first time out in a 300whp miata.

This guy is at 350 and wants more.


I'm in awe.

sub'ed.

Just here to say this is completely impossible and I won't believe it until I see it. :skid: Oh- and you should go dry sump with tank-in-trunk since you'll be pumping oil all the way back to the rear of the car. That'll simplify things. :D

Just... Just do it. Just do it man.

Small update, had a change in the plan. Everything the same as above, except change "Whipple" to "small turbo in normal location". Got a little bit done, all SC crap is off the car, header gone, oil pan tapped, valve cover tapped for rear turbo drain to return, shelf cut to firewall for extra clearance (V8 style, should have done that years ago, highly recommend). Haven't fabbed anything, just getting what I can done while I wait on parts to arrive. Plan to remove muffler and find a home for the GT45 tomorrow.

Codrus, not on a dyno, but I did play with adding timing at the drag strip, and it did not help my mph or ET any. That's all I got to answer that question.

OK. FWIW, I really do recommend dyno tuning next time -- a drag strip's mph has too many variables in it to give you the back-to-back comparison you need to measure the effect of adding timing. Even if you could factor out the effects of varying temperature, traction levels, air density, etc, it's only giving you one number instead of the 20 or so you need (torque at 250 rpm breakpoints from say 3000 to 8000).

--Ian

Fucking called it! Compound-turbo feeding a what, cold side supercharger? Or are you just leavingi t off now