Changing Turbo.(Fuel adjustment advice/PS 1000)
 

My old turbo was supposedly a TO4S and since the turbo was going(blew smoke on decel on dyno) I decided to try something else.

This is the old turbo specs.

Specs that I got from the CHRA are:
the Front turbine wheel is 66.6 and 84.
The back wheel is 11 bladed. 64.3 and 74.3
The Center cartridge has no visible part numbers other than an |"A" and a "Y5" raised in the cast.It is oil cooled only.
Exhaust housing is a .96 Undivided with a 3 inch Vband out.
Compressor housing is a .70 (says M24 and EC-1 on it..)

Now I am changing the Turbo to find out IF the "smoke problem"(that is still present But not as much after a "rebuild") is engine related or turbine related(bad oil bearing in turbo.

The dilemma is I am now faced with the fact that this turbo is going to push more air.

Specs on new turbo T76:
- 76mm Wheel Compressor
- P Trim .96 A/R Turbine
- 102.4mm/76.7 Compressor Wheel ***(concerned ..bigger than original T04S)
- 74.1mm/64.6mm
- 3" V-band Hot Side

SO,my question is Without having to get a "tuner guy" to Dyno this thing Again,can I adjust fuel..say 10%more on my PS1000 to safely compensate for the extra air this thing is gonna push?

Specs on car: made 357 at the wheels on the dyno with the old nasty smoky/squeaky Turbo.
T04s..
S5 TII stock ports with Fd upper and TB/Tps.
ID 1000/2000
PS 1000 Ecu.
Jgs blowoff and wastegate(Hks cast mani on 3 inch rb exhaust).

I hope this is enough info,the car is ready for coolant and a test run.

Thanks Gents.
STYX.

translating:

your current turbo

compressor is typical midsize wheel.... 7 average square inches... 550 rotary rwhp capable max.

turbine P trim 5.89 sq inches

new turbo

compressor 9.9 sq inches

turbine P trim 5.89 sq inches

you would be going from a midsize to a LARGE size turbo based on compressor sizing. similar to an HKS T51 SPL, larger thane a GT4202.

trim is quite different. you have a 63 trim presently which is spool unfriendly and the larger turbo is a spool friendlier 56 trim.

working against you is the overall compressor size... larger than a GT4202 or some of the BW S475 turbos... these turbos can make in the area of 90 to 100 pounds per minute compared to your present turbo around mid 70s.

there is also the size of your hotside wheel compared to the compressor... most turbos w 10 sq inches of compressor have more than 7 inches of turbine. you have 5.89. more backpressure, more heat rolled in to the incoming charge air on the next rotor face.

finally, my rule is bring enough fuel, always, for peak turbo output... if your wastegate sticks you could be looking at over 90 pounds per minute of air. if you don't have the fuel you will be looking at a new motor.

90 pounds of air at 10.5 AFR is 9.45 pounds of fuel per minute net of duty cycle and lag...

9.45/6.35 = 1.488 gallons gasoline per minute or 5633.

5633 X 1.35 (lag and duty) = 7604 of injectors. you have 6000.

you will also need a proper fuel pump.

this is a monster turbo w a somewhat challenged hotside.

your current turbo can do over 500.

howard

A simple awnser is no, you its not that simple unluckly, :( that new turbo is biiiiggggg

Regardless of the fancy turbo math, the short answer is no. The mass will be different at different MAP values. A universal trim will not work.

^ lol. I did this to when i changed to a bigger turbo. added about 15% to start, but like Chris said i will need further tuning.

ah ..FUDGE Nuggets..

Someone sell me a freakin turbo..or BUY This POS.

I just went for a 1/4 mile drive and hit 14 AFR on acceleration..Screw that..Parked it.

Buy which turbo?

Turbo?..whole damn car!

full retune bruh

no way around it

Any change you do that alters the flow or load per rpm will need a re-tune.

turbo is definitely one of them.

the vacuum side of the table should remain basicly the same... do u have a wbo2? if u have connect it to ur haltech, add like 10i-15ish percent overall fuel and make a 4th gear pull that u logg on a computer. Ask a friend watch ur afr gauge and let go fast if its going to lean, watch the loggs and add fuel where its needed and remove where its needed.
This should work atleast up to 10ish psi and should take like 5-10 pulls, then u can just finish it of with a tuner on the dyno with knockbox etc.
do u have conservative timing?

Be careful!

Ok then,I have TWO Choices.This is pretty well to find out if the turbo is my problem..PLUS get a last run in before the weather turns into Crap up here.

One is to change the wheel and compressor housing on the turbo to keep it the same as before.
The plates will not mate(different size) so I would have to change them.(that 4 bolt affair to the compressor housing)

OR..Can I just change the wheel and NOT the housing(retain the bigger compressor housing but run the smaller "before" wheel)?

Dont, the balancing isnt the same

UPDATE!:

In order to do this as "cheap and effective as Possible"..(yeah,stay with with me on this.)

My solution is I went ahead and ordered a cheap ass Turbo that has the exact wheel specs as the OLD Turbo,except the hotside is 1.00..
I will however be using the OLD hotside (.96) and therefore by rights I should have the SAME turbo setup as before and not have to Retune.
This gives me a chance to find out IF the Bearing in the old turbo was Fudged and also relieves me from tossing on another turbo that is not compatable to the Tune I presently have.
This saves me from having to drive the car 500km or Flatbed it to the tuner as there are no tuners within the are a to do a rotary.

So,new comparable Turbo..no extra tuning needed..and Hopefully I get to the bottom of my problem..(cheaply!!)

*the car ate up all the extra funds that I "could have" thrown at it,so I had to keep it Frugal yet accomplish what I set out to do.
I still have the winter to build another engine and setup for Spring,which I have the parts for (S5 TII with reinforced tear iron) and plan to do anyhow.So in effect this Cheap turbo allows me to juggle my finances and keep going..lol!

this maybe a stupid question, but why not just rebuild the old turbo? or is it ball bearing?

The price of the new one is less than getting the repairs done!...and who is to say that the turbo is actually bad?..This is what I am going to find out.
In the long run it is buying a cheapie to source the problem.
If it IS the Old turbo then the new one won't cause smoke.
No smoke,Problem solved,I get the car running..run gingerly until I can afford another Brand name turbo(or get the old one "repaired")
IF it is NOT the turbo then the engine is the Problem.(then that's another problem!)

Did you observe the ports/rotors with the turbo manifold removed? Was any of them oily?

The exhaust/down pipe flange is a Real PRICK to get together with one person,so instead of taking the whole system off the engine I took the CHRA and compressor off the exhaust housing,leaving the Exhaust housing and downpipe/manifold wastegate etc intact on the car.

Anyways,the car will not smoke until it gets high RPM ..mostly HI end 2nd gear,or after a dyno run..lol!
The car smoked on dyno.End of run.,(see one of my posts..has a video).Other than that the car has balls and will play soccer!

I may be wrong but I still think you should not rule out your oil control rings.

Originally it was the turbo,as I took it off and Man!,the thing was not spinning freely.
I got it rebuilt BUT the thing is The rebuilder is mentioning oil pressure of the Rotary engines.
I restricted oil to the setup and got less smoke but It didn't make it go away completely.

Now I have NOT ruled out Oil control Rings,but the original diagnosis of it being the turbo led me to say "I should try another turbo"..BEFORE I go and rebuild.

As I said I got another Turbo being shipped and have another engine I am cleaning up right now to get rebuilt.It should be an experience as I have never done one in the 9 years I have had Rx7s!.But I am watching Aaron's videos and taking notes!
I'll keep you guys up to date once I get the New turbo on to let you know if indeed that was the problem.
Thanks to all who replied.Cheers.