Milano Twin Turbo

Greg Gordon
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Re: Milano Twin Turbo

Post by Greg Gordon »

granturismo:

Thank you. Believe me I thought long and hard about the pipe's routing. In the end, no matter which way I set the compressor outlets, there was some sort of problem to deal with. Like all solutions, the way I set it has advantages and disadvantages.

It's true the extra length of pipe from the passenger side takes more energy and time to reach the "Y" before the intercooler, but the actual numbers make it seem pretty insignificant. There just isn't that much volume in that pipe as compared with the total flow of the turbos. The time it takes the passenger side turbo to fill that pipe is measured in thousandths of a second. The extra drive power is so low, I have no idea how to measure it.

Ideally in a twin turbo setup, everything (exhaust and air) would be equal length and with equal bends. The reality is, it's not really possible, at least not in practical terms. Remember the turbos are not mirror images of each other, so even their basic structure makes things unequal length right from the start.

I am pretty sure the owner will be putting bigger tires on it. That will help with traction, and the car needs it.

Greg

gran turismo
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Re: Milano Twin Turbo

Post by gran turismo »

Greg,

I did a quick pressure drop calc with a compressible flow program.....

I based the calc on 100%VE at boost pressure, 7000 rpm, 204 F turbo outlet temp, 140 F intercooler outlet temp, 1 psi drop across intercooler, 10 psi at the throttle body, estimated pipe lengths, fittings. I used 2" tubing for the turbo outlets and 3.5" tubing between the intercooler and throttle body.

According to this calc the passenger side turbo would need to put out 13.4 psi and the drivers side turbo would need to put out 12.8 psi to get 10 psi at the throttle body at 7000 rpm. (probably not significant)

It looks like you could get away with a little bit smaller tube between the intercooler and the throttle body (like 3" dia) if you wanted to save some space and not suffer any significant increase in pressure drop.

Also the 2" turbo inlet pipes have a very high velocity (over 16,000 fpm) and pressure drop (about .4 psi). I know that you are matching the turbo inlet size but it might be worth experimenting with a larger size and reducing to the turbo inlet pressure drop.

Greg Gordon
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Re: Milano Twin Turbo

Post by Greg Gordon »

Good work, but I suspect all the pipes are quite a bit smaller than you think. The turbo inlets are 1.75", the outlets are 1.62". The pipes in and out of the intercooler are 2.5". All the pipe sizes are matched to whatever they connect to. In other words, the pipes connecting to the turbo inlets are the same size as the inlets, etc. The pipe out of the intercooler is actually 2.5". Of course it goes up to over 3.00" at the throttle so it can connect.

The temperature out of the intercooler is only about 20F above ambient, about 90F on a 70F day. There is no way the pressure drop through that intercooler is 1psi, it's probably more like .1 or .2 psi at these volumes and boost pressures.

I am not saying it can't be improved, but I think the gains would be minimal. As it is the turbos spool faster than most other turbo cars I have recently driven, these include a WRX, Callaway GTV6, and Ford 2.3, the last two use similar IHI turbos. I can make all the boost I want. It's set for 10psi, but I know for sure it can make 12 because I set it that way for one quick run before I turned it back down. I am guessing it can make 14psi with the wastegates set for max blow.

At this point we are focused on tuning. I have not been able to go to the dyno due to scheduling conflicts.

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Steve R
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Re: Milano Twin Turbo

Post by Steve R »

Hi Greg - Nice job indeed!

Is that car still running a transaxle, or a front mounted or otherwise stronger gearbox?

I'm curious as that motor spec should put the output somewhere well up over the interesting side of 300bhp & 300lbft torque. Wondering how the driveline will hold up to that kind of stress!
83' GTV6, 3.0 24v supercharged

Greg Gordon
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Re: Milano Twin Turbo

Post by Greg Gordon »

Hi Steve,

It's running a transaxle. The turbos are pretty small and probably have max flow capabilities just shy of what the transaxle can handle.

Greg

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GarthW
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Re: Milano Twin Turbo

Post by GarthW »

Mine is making abit over 300hp, transaxel is handling it fine, but i dont drive it like an idiot either, also with around 460nm of torque, you hardly have to rev it. 8)

And that is with a small turbo.

Sorry Greg, dont mean to high jack..when you going to tune her up??
Image

Selling 1985 GTV6.

Ecu and injectors, lightened.....plays music.

Greg Gordon
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Re: Milano Twin Turbo

Post by Greg Gordon »

The on road tuning is pretty much done. I am trying to get to the dyno, but my flying job is keeping me away a lot.

Greg

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fedezyl
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Re: Milano Twin Turbo

Post by fedezyl »

Greg Gordon wrote:The on road tuning is pretty much done. I am trying to get to the dyno, but my flying job is keeping me away a lot.

Greg

Got to love the airline business, high season is keeping me from finally finishing up my giulie V6 project, hey greg, what do you think about a G60 compressor out of a 2.8 corrado for a 3L v6??

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Giuliettaevo2
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Re: Milano Twin Turbo

Post by Giuliettaevo2 »

G60 charger is a piece of sh*t... You can wait for it to self-destruct. :(

The G60 has a 1.8 litre engine(160bhp with charger), not 2.8 that's the VR6. :wink:

It also is a rather large thing, and that's just the outside dimensions not the CFM it produces.... :(

They were very popular over here for a few years but now you hardly see them anymore. They're very expensive to replace if broken and rebuilding them is also specialist work. With a small pulley on they may ned rebuilding every 10.000 km or so. :shock:

Eaton M64 from Mercedes is a loved upgrade for the G60, as is the turbo..
Drive it like you stole it...

Greg Gordon
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Re: Milano Twin Turbo

Post by Greg Gordon »

Hi fedezyl:

Yup, the airline business is tough for pilots right now. I am gone 18-22 days a month, going all over the planet in a 767 and making very, very little money. It's darn close to what I would get on unemployment! At least I get to go to some cool places and see newer Alfas. Tomorrow I am heading to Cyprus. I wonder if they have Alfas there.

Enough of my airline rant. Regarding the G60, I agree 100% with Giuliettaevo2. VW, went out on a limb trying to use a vane type supercharger instead of a more proven type like a Roots, Lysholm etc. Nobody has ever had real success with that design, but every 25-35 years someone tries it. Now that I think about it, it's usually the Germans, for whatever reason they always do oddball things with superchargers, 90 deg drive mechanisms, on/off clutches, vane types, etc.

Greg Gordon,
www.hiperformancestore.com
www.okinjectors.com

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