$350 Turbo made 253rwkw @ .9bar

[BOOSTD]

I have been experimenting with a Hybrid VG30 as some of you know. After alot of teaks I have found a combination that works.

First things first. The turbo cost me $350 as I had all the machining side of things done free.

Stage 1.

VG30 bb turbo 49mm comp .6A/R 42mm turbine (ceramic) .81A/R

Action: Installed a TO4 Vtrim Compressor wheel.

Source: Compressor was bought from Adelaide Turbo Services

Machining of comp cover done by Russell Engineering

Result: Car made a slight power increase from 218rwkw to

224rwkw at less boost(.9bar). Increasing boost

resulted in power loss. Did some research and found

that any boost increase was causing exhaust gas to

flow back into the cylinders on cam over lap. This was

the result of to small a turbine causing excessive back

pressure. Turbo made 15psi at 2600rpm! Sounds

impressive but actually is very bad. Turbo suffered from

extreme surge as the compressor was trying to flow

more air at low rpm than the engine could digest.

Thinkpad-- Came to the conclusion that if I machined out the turbine snout I could decrease back pressure and increase lag. From researching the compressor map I found that 15psi had to be made by 4000rpm or later the pass the surge zone.

Stage 2.

Action: Removed the turbo and machined out the turbine snout

by 5mm in diameter. Total now 47mm

Source: Any machine shop with a lathe.

Result: Turbo now made 15psi by 3600rpm. Also was able to run

alittle more boost- 1bar without loosing power.

Detenation levels decreased slightly and power inreased

by 10kw to 234rwkw.

Thinkpad-- yep you guessed it, pull off the turd again and

machine the turbine snout out some more.

Stage 3.

Action: Machined a further 4mm out of the turbine

snout increasing the diameter to 51mm.

Result: Makes 15psi by 3800rpm with surge sometimes.

Obviously right on the surge line. Power increased by

19rwkw to 253rwkw. Any increase in boost did make

an increase in power, up to a theoretical 270rwkw @

19psi however detenation was present at any boost over

14psi. Either a reduction in compression or Tolulene was

needed for higher boost levels.

Thinkpad- Boring out the turbine to 52-53mm would be about perfect and eliminate surge.....I might do it when I get the energy to pull off the turbo again.

I will supply my dyno sheet along with Air fuel mixtures next week when I get use of a camera. I have attached the Compressor map for info to those in the know......R u not in the KNow??? Do a search for " How to read compressor maps"

[meggala]

the series 4 rx7 compressor wheelis 51 mm the series 5 one is 54 or 55 mm and they are steel I ahve driven an r32 with this turbo set up with a t4 front wheel worht some though.

btw still ahvent fittted that turbo waiting for the ceffy to come back. also detonation could be because of a lack of fuel have you upgraded injecotrs and afm?

cheers

meggala

[EnricoPalazzo]

Wow thanks Matt!

Umm does the VG30 bolt straight on? Also would u see any benefits in a mildy modded line, such as mine, with only full exhaust and POD doin this? Or is it best for a car with ECU and FMIC?

Thanks!

[BOOSTD]

Meggala: yes fuel was leaning out on extra boost. Needed 11:4 up top to keep cool. ps bought a Cefiro today auto turbo for $5200.....why buy a silvia

Enrico: VG30 is a straight bolt on. ECU and FMIC is an absolute must.

[hippy]

great stuff man .. i didn't really understand any of it .. but yeah thats great!!

[Guest RedLineGTR]

sweet....very nice power from that turbo...a little time & planning gos along way

[zandi2000]

where u get ur cefiro from if u dont mind me asking?

[dabigbolf]

so after all you work done to the turbo. what was the total sum for the work done...

is this a $1000 upgrade, with all machining extra done...

from sratch with a stock turbo..

[MRK25T]

What sort of work has been done to the car apart from the turbo.

I guess from this thread you have a FMIC and a modified/aftermarket ECU.

I wouldn't mind making 230rwkw so maybe I should sell my high flowed turbo and buy one of these?

Mark

[Steve]

Good work, nice to see a bit of R&D being done and some good results coming from it.

Just wondering what formula you used to determine the engines airflow?

Cheers

[BOOSTD]

dabigbolf: You will need a VG30 exhaust housing $50, and the machining and balancing will cost about $100, TO4 Vtrim Compressor wheel $250...so about $400 all up.

MRK25T: What size and type compressor wheel does you high flow have?? Has the exhaust side been modded?

Steve: 21st century performance has a graph for flow versus rpm.

[BOOSTD]

The Cefiro was bought from www.yahoomotorsport.com

[dabigbolf]

I am very close to being convinced to start hunting down these parts to build a turbo the same.

A gt30 was the plan, but summing up the costs involved, i could have a turbo poducing good power and change left over, to put towards a power fc, and a decent set of injectors.

I have heard that i can just use my r33 turbo, and fit the vg30 exhaust housing to it. Then i could do the machining, and fit the t04 front wheel. Or do i need a complete vg30 to start with.

Or

would a complete turbo assembly be what you have stated-

"VG30 exhaust housing $50, and the machining and balancing will cost about $100, TO4 Vtrim Compressor wheel $250...so about $400 all up. "

And that would include internal wastegate

but i would use the oil return lines off my r33 one.

whats the best way to go about getting a turbo such as this one made up.

E.g dont want to buy a complete vg30 turbo if i am gonna get rid of half of it.

cheers.

[BOOSTD]

Keeping ur RB25 turb is the go, VG30 turbs are getting old now and hard to find with good bearings. The VG30 exhaust housing will bolt up, just make sure the housing is from a BB VG as the non BB won't fit. Any Turbo shop will be able to find the parts if the don't have one laying around. Make sure the Exhaust snout is bored to 10mm bigger ie 52mm as mine still has very slight surge at 51mm. Should expect 15psi @ 4000rpm and start to make boost at 2500rpm. You should expect a reasonable life from your turbo also as it spins 20,000rpm slower to make the same boost.

Warning: My two week old 275 18's are past the wear bars already from this turbo. I turned the boost down to 11psi and still smoking em at 60kph...grrrr

[dabigbolf]

so basically this is just the t4/t3 hiflow.

I keep the same stock back wheel off the r33. Its just the vg30 exhaust housing.

thanks for the help.

will see what sort of responses i get from a couple of turbo places down here in melbourne.

cheers

[BOOSTD]

I will post my dyno Graph, quite nice to look at, goes up like a rocket then trails off in the last 2500rpm because of my timing retard. This turbo will make 270+rwkw with Meth Benzene.(race fuel) Mick from subzero got quite excited when its started rising toward the 300rwkw mark. A 0.7 A/R comp housing would help it make even more power... The Vtrim Comp wheel is 54.5mm inducer(smallest part) and the turbine 52mm( most unrestricted ) If you check those sizes against HKS that equates to around 420ps apples and oranges I know but a rough guide no the less.

[Guest Robo's]

Sounds like an excelent mod, and cheap if you understand the principles.

Im learning

[RS500]

BOOSTD,

for this turbo to be making the 253rwkw or approx 420ps as u state at 1bar, you'll need to be pushing about 45lbs/min which according to your compressor flow map for the V-trim wheel means that it's running at ~105,700rpm and about 55% efficiency.

not sure that it's as good as you're saying.

[Steve]

How do you convert lbs/min to kw?

[BOOSTD]

Times by 9 for rwhp

RS500 45lb/min equates to: 45x9=405hp /0.746 =302rwkw