Twin turbo 3.0 or 3.2 what size turbos for 400+ hp? - PeachParts Mercedes-Benz Forum

Turbo E320 · #1 11-21-2008, 03:04 PM

Just throwing around options but this is the most likely as my 190e project will be circuit track driven car as well as a weekday driver. I know a good m103 or m104 can make 400hp reliably already so I might as well continue using the I6 motors. I want the car to spool "fast" for the circut track use. It has to be reliable horsepower so I still want to run lower boost(under 15) which means a system with a 600 or 700hp capacity.

It took me 2 months to figure out the turbo for my e320 so any help you can give will be appreciated.

whipplem104 · #2 11-21-2008, 05:32 PM

Get Corky Bells turbo book. All the formulas for selecting the correct turbo based on flow are there. Once you do the math then find a turbo with the correct flow chart and ar ratio. I would think that something in the gt30-35 area would be perfect for what you are looking for. Twin scroll and ceramic ball bearings for a fast spool. Also get the shortest and correct size intake tract. If it is full race purpose car a new intake manifold will really help.
Remember that good ducting is as good as sticking the front mount right in front of the radiator. Look at porsche.

KarTek · #3 11-21-2008, 08:40 PM

Right off the top of my head I'm thinking either Garrett GTP038R or Holset HE351. The Garrett is ball bearing and the Holset is VG. I think either would support your HP requirement.

If you give me the desired RPM you want to develop your 400 HP, I can plug it into my spreadsheet and give you actual air flow and pressure ratios that you can plug into the maps.

Unfortnately the spreadsheet is at work so it'll have to wait until Monday.

jhodg5ck · #4 11-21-2008, 09:00 PM

+1 on Corky's book...it came highly recommended when I wanted to learn about FI and having read a few books since then it's still my fav/fall back etc...

As an aside, there are turbo calculators out on the web..

Jonathan

Turbo E320 · #5 11-22-2008, 01:25 AM

The car will have only a 100rpm increase from stock to 6500 rpm. I have checked some of the turbo calculators but most are out of date by several years.

KarTek · #6 11-24-2008, 09:00 AM

OK, I ran some numbers and you're looking at 44#/min and a PR of 2.23+ (depending on how good your intercooling and induction is...)

Garrett GT4088R would fit perfectly but it's big and probably pricey. GT3582R is also a good match and a smaller physical size. Not quite as perfect as the 4088 but will spool faster. The littlest turbo I'd put on there is a GT3076R. Any smaller and you're really beating the air up.

The Holset HE351 might work if you can find a map for it.

As alternative, you might want to look at some of the Turbonetics stuff... GT-K500?

This is also shooting for a AFR of 12:1 which is a little on the pudgy side.

RBYCC · #7 11-24-2008, 09:16 AM

I run twin Garrett T2's which are no longer available.
Each compressor is piped to three cylinders using discrete manifolds.

The smaller turbos spool up extremely fast, no lag and are very quiet.
Boost fixed at .48bar and AFR is 12.5:1 under boost.

Two major players with the best experience on M103 and M104 Turbocharging were Mosselmann and Turbotechnics.
Both chose twin small compressores with low boost and required no modification to the engine internals or fuel delivery system.

As far as dyno numbers they are only a tuning tool givng before and after mod comparisions.
High numbers that are thrown around forums are usually for bragging rights and rarely backed up by any timed acceleration runs.

I pulled 230RWP on a Mustang Load dyno an increase of 100RWP over stock.
With stock 3.07 rear gear timed acceleration to 60MPH is around 5.5 seconds and 1/4 mile high 13's around 100mph trap.
Drag radials will bring the time to mid 13's...
This is on a 4000lb vehicle ( car, driver, fuel)

Don't build a high rwp hand greanade...build it fast but also reliable...!

Ortolan · #8 11-24-2008, 01:58 PM

I also run twin T2 units on my M104, however, due to the increased displacement (3.5L) and boost pressure (14psi) the engine is unable to rev past 5000rpm. The turbos just can't pass enough air though.
I was looking at twin GT25 units as a replacement to maintain the same fast spool & torque curve but allow the engine to rev to 8000rpm.

PUMPISH · #9 11-24-2008, 05:47 PM

who sad that twin turbo is better and give faster spooling time???

Each turbocharger getting exhaust from the 3 cyl each.

If you want to fill a tank with 10 liter water from the 2 small cans with a little holes of from the dobble as big can with a dobble as bif hole. It takes exatcly the same time.

BUT with a singel turbocharger you can stil use ignition pulses by using twin entry turbocharger and manifold wich gives you faster spool and much softer curve.

Buy ballbearing??? Total pointless.
We have tryed ball bearing on many different engines and mercedes engines and it does not give any faster spool. Only cost more money and more sensitive.

Our TB60 t3 divided 60mm inducer (600hp) starts spooling at 2000rpm (m103 engine) and pumping up to 6500.

TB70 t3 divided 70mm indiucer (800hp)
starts about 2300 and up to 6500

GT45 (900hp) starts at 3000rpm and all the way up tp 7000.

With a stock M103 engne you can easy rev 8000rpm if you want it.

7200 is normal if you choose Turbo for about 700-800hp

Turbonetics t61 is allmost the same size like our TB60 but much slower spoole becaurse of heavyer shaft

New TB60 is producing now and comes very soon

p.s. Even Supra MK4 makes much better and faster spool with a Singel Turbo convert then stock twin.

Twin turbo is something poeple belived at 80s and 90s was a best before they find out that Truck pulssplitt system and singel turbo is much better

c280nz · #10 11-25-2008, 02:32 AM

im with pumpish,

if your building a high hp road/race car big single is better.

RBYCC · #11 11-25-2008, 09:04 AM

Quote:

Originally Posted by PUMPISH

who sad that twin turbo is better and give faster spooling time???

Twin turbo is something poeple belived at 80s and 90s was a best before they find out that Truck pulssplitt system and singel turbo is much better

Roman...

You need to be a consultant to the auto manufacturers who are stuck in a time warp..

BMW got it wrong with the 335I TT introduced in 2007...
And how foolish was AMG with the SL65 TT...

And then there is APS with the TT installs on LS1 and LS2 small blocks..

Technically a single turbo is more efficient. several things are in it's advantage: less surface area for heat to escape before it enters the turbine, better flow/inertia ratio, less total system weight, higher compression efficiency possible, higher air pressure/flow rates for the backpressure it creates, the entire system can be made shorter and lose less pressure over the whole system.

But there is one big disadvantage: the single big turbo only has all these advantages over a very small operating range.

Where as a multi-turbo system misses a percent or two in overall system efficiency it more than makes up for that by achieving close to peak efficiency over a wider operational range. This is the key to why multi-turbo systems can achieve better drivablity in real world applications.

To state with no doubt that one is better then the other lacks true knowledge of application.

Maybe they wanted to build a more reliable and durable vehicles instead of hand grenades ?

I admire what you have achieved, but to achieve more your mind must always remain open to ideas and concepts other then what you subscribe to !

Ed A.

Joreto · #12 11-26-2008, 05:24 AM

Quote:

Originally Posted by PUMPISH

...... With a stock M103 engne you can easy rev 8000rpm if you want it.
7200 is normal if you choose Turbo for about 700-800hp

Do you mean that the stock valvetrain(springs, retainers ect.) has no problem handling 8000 rpm, would it be safe to rev a stock m103 with turbo to 7000-7200 rpm ?

As to single vs twin turbos, wouldn't a properly sized single give about the same response as a twin turbo, say a single matched to give the same power as the mosselman twin turbo ? I my opinion atleast the response time would be similar since the single turbo won't be very big and it'll have all the exhaust pulses going into it where as on a twin (setup like mosselman) every other exhaust pulse goes to one of the turbos. Also I think that most lag from the single turbos is caused by using very large turbos, say capable of 500hp-600hp when you only intend to put out say 350-400hp. To sum it up sizing is everything, for instance if mosselman intended the kit to be capable of say 500hp then the twins would have been bigger which would have
resulted in more lag

.

P.S.

Quote:

Originally Posted by RBYCC

.....Boost fixed at .48bar and AFR is 12.5:1 under boost.

Isn't the AFR a bit on the lean size? I know that .48 bars is not a lot of boost but I always prefer to tune to ~ 12.0:1 under boost just to be on the safe side (in case of say a clogged injector or so) . Also any idea what your total timing is @ .48 bars, I read that you pulled the resistor to get a bit of retard.

Turbo E320 · #13 11-25-2008, 11:08 PM

I wanted to use twins so I could have the power at lower RPM. I cant dance around at 6000 revs all through the track. At some points in this course you will be pulling out of a corner at 3000 rpm.

On the supra note, supras have become straight line cars and most big power single turbo setups on supras are lag monsters. Theres a 850hp black supra around here and it gets jumped by 400-500hp sti's when racing for a few moments before the turbo finally hits full boost.

c280nz · #14 11-26-2008, 01:08 AM

get a manual box and anti-lag

and just chop thru the gears.

haha im just tryn to keep the debate going!

what about running a similar turbo to on your e320, how does that setup go?
very laggy?

whipplem104 · #15 11-26-2008, 01:43 AM

I would say if you want truly linear throttle with lots of power down low then use a supercharger. There is no lag and the power is very predictable and easy to control on the gas pedal.
If you are dedicated to a turbo set up then for the hp numbers you are looking for there is no reason that you cannot have almost full boost by 3000 rpm with a twin scroll turbo. I would think that you could actually have more even earlier. I work on an audi aan rallye quattro that uses a little turbo with a restrictor. This thing makes full boost [18lbs] by 2200 rpm and full torque as well. It would easily make over 400 hp without the restrictor and it is a 2.2l 5 cylinder. As mentioned here the mercedes v12 twin turbo makes full torque by 1800-1900 rpm. Cut that motor in half and you have a straight six.
If you wanted full torque by 1900 rpm and 800 hp then you would probably have to do something else.
Also for racing you could do a true bypass to keep the turbo rpms high while out of the throttle. Mercedes and I assume others now do this. Keeps the compressor from stalling from the pressure spike when throttle is closed.