# TECH : 2.5 FUTURE - Turbocharged or Supercharged



## Issam Abed (Feb 12, 2004)

Hey guys, 
I would like to engage in a serious discussions pertaining to the future of this motor with most of you. If you had the money which forced induced route would you go and why? 

If you have allready gone the turbocharged route do you mind posting up some details about your build and why you did what you did? 
Thanks


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## tay272 (Aug 22, 2007)

Ive been waiting for someone to make a supercharger for this engine for awhile now. I personaly prefer supercharged over turbocharged for a few reasons. One, I like the whine a supercharger makes more then the whistle of a turbo. Two, turbos tend to wear out and things break on them moe easily then a supercharger. In my opinion a supercharger will always be more reliable then a turbo. Three, I like the power to be there right away and not have to wait for it as you would with turbo lag. And four, I just wanna hear the sound this I5 makes when its a supercharged beast!


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## nothing-leaves-stock (Mar 1, 2005)

i've been waiting for someone to come in and wnat one supercharged. we have a setup we think will work mint on a 2.5L. just waiting for the right car. 
i like turbo's more, BUT i think the 2.5L with a SC with be a fun torque monster. and since no one has done one yet, theres no way to know how it will act and which is better. 

in the past SC and weaker in power and a bit in reliablity. like on VR6's and even R32's. we have swapped sc for tubos on both the cars for a few customers....and NONE looked back! all very happy with the upgrade. 

in for discusion and info:beer:


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## thygreyt (Jun 7, 2009)

i cliked on supercharged even thou i'm going turbo myself. 

i just would like to see a 2.5sc even if just 1...


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## kevin splits (Aug 23, 2010)

was gonna go turbo, but put money down to reserve the new r :laugh: a shop around here is jokin around doing a supercharged 2.5 jetta, :laugh: they seem to know it will work but i want to see it to believe it, because i thought i came upon a thread a while back and saw a guy trying to figure it out for a year or two, idk maybe im wrong, would sound nice tho :laugh: 
turbo for me tho :thumbup: 
(will be selling all my turbo hardware in a week or two)


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## lessthanalex (Oct 12, 2009)

Hands down supercharger. Supercharger feels iconically German to me, maybe that's cause I learned how to drive on a Benz Kompressor. I love how the power feels in an SC kit versus a turbo. If I had the money, I'd be going super right now. Maybe when I graduate...


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## DerekH (Sep 4, 2010)

Super charger for me. To me it just seems to make more sense with the way this engine is set up in the engine bay. Not to mention it already has more than enough torque to spin a supercharger with no issue. Id like to see one with a real twin screw super charger though, not the crap they put on a honda.


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## BlackRabbit2point5 (Sep 6, 2007)

Hands down turbo... Coming from someone who already is turbo. On the c2 stg 2 setup the torque is more a plateau than a curve, the 2.5 already has enough down low. With the turbo the power comes in when you need it letting the natural grunt of the motor get you off the line smoothly. Wouldn't surprise me if a supercharged 2.5 would run into tons of transmission problems. I haven't even touched on efficiency or potential.


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## pennsydubbin (Mar 3, 2010)

BlackRabbit2point5 said:


> Hands down turbo... Coming from someone who already is turbo. On the c2 stg 2 setup the torque is more a plateau than a curve, the 2.5 already has enough down low. With the turbo the power comes in when you need it letting the natural grunt of the motor get you off the line smoothly. Wouldn't surprise me if a supercharged 2.5 would run into tons of transmission problems. I haven't even touched on efficiency or potential.


 
I agree with you here. The 2.5 does have enough down low and the turbo would be a nice transition into when it needs more power. The down low torque does make it a plus to supercharge it for fact that it robs power to run the supercharger, but i feel that the supercharger would result in too much low end torque and not a smooth power curve. This is just what I think would be the case, but I could be completely wrong


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## [email protected] (Apr 14, 2005)

pennsydubbin said:


> I agree with you here. The 2.5 does have enough down low and the turbo would be a nice transition into when it needs more power. The down low torque does make it a plus to supercharge it for fact that it robs power to run the supercharger, but i feel that the supercharger would result in too much low end torque and not a smooth power curve. This is just what I think would be the case, but I could be completely wrong


 You are basically moving the powerband around with the difference between the turbo and the s/c. 

However, you can do that just as easily with a turbo, just pick a smaller one. 

Torque down low? 28RS and you are all set. 

HP up top? 30 series. 

Don't need a blower to get torque down low.


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## eatrach (May 13, 2004)

Turbo is more reliable than SC. I had an SC on my E36 M3; it was very noisy which led to a failure. Had it replaced but still the noise those bearings produced made me rethink that I should have gone with a turbo instead.


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## dmgraz (Jan 3, 2008)

Thank you for starting the poll. Supercharger all day everyday!


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## kevin splits (Aug 23, 2010)

how bout 2.5tc(twincharged):laugh: like the motor the euro mkv golf gt has, but the 5 cylinder twincharged would be kinda cool.. a little much but cool :thumbup:


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## b1aCkDeA7h (May 27, 2008)

kevin FaKiN spLits said:


> how bout 2.5tc(twincharged):laugh: like the motor the euro mkv golf gt has, but the 5 cylinder twincharged would be kinda cool.. a little much but cool :thumbup:


 I believe a reviewer of the Euro twincharged Golf GT said that it wasn't very smooth. I believe the quote was: 

"The smoothness of someone in a wheelchair falling down some stairs." 

I for one have never driven a supercharged car so I would like to try one out first before I make a pick. That being said, I have driven an Audi with a tuned 1.8t and a 240sx with a tuned SR20DET and they're both great fun.


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## kevin splits (Aug 23, 2010)

Ya but this would have double the displacement plus an extra cylinder. It would be instant boost if u charge the turbo with the sc. And I read a review similar but can't find that one? Also looked in an old issue of pvw and a fix to that problem was a simple re-flash. 

Build the motor with real low compression, gt40, powered by a twin screw! Holy sh** instant boost at the tap of a gas pedal!


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## Issam Abed (Feb 12, 2004)

tay272 said:


> turbos tend to wear out and things break on them moe easily then a supercharger. In my opinion a supercharger will always be more reliable then a turbo.


They are equally reliable when done right


[email protected] said:


> However, you can do that just as easily with a turbo, just pick a smaller one.


:thumbup:
Nice to see you in these parts Keith



nothing-leaves-stock said:


> i've been waiting for someone to come in and wnat one supercharged. we have a setup we think will work mint on a 2.5L. just waiting for the right car.
> i like turbo's more, BUT i think the 2.5L with a SC with be a fun torque monster. and since no one has done one yet, theres no way to know how it will act and which is better.


Thank you for your contribution Josh.

Now I created this thread to get feedback from people to see where and what direction they would go in. Basically just giving us a general basis. Since the beginning of the year I have been actively working on both a turbocharged kit and a supercharged kit for the 2.5 motor. In the end the choice was clear that a turbocharged kit would be more favorable and I will explain why.

*Supercharged:*
I have developed kits for VW engines using Rotrex superchargers in the past and HKS units currently so naturally if I was going to use a supercharger it would be one of these *units.*
Another option was using an Eaton unit with a cast intake manifold with built in laminova cores but after working it out the cost of this would have been in the $5000 USD range so it was back to the HKS unit. The HKS units are very well engineered and offer great performance for the packaging involved , not to mention are affordable compared to using an Eaton unit.

So what stopped development? The primary problem with the 2.5 motor is the accessory belt system. As most of you know the crankshaft pulley only turns the A/C compressor. The A/C compressor has a dual serpentine pulley which rotates the rest of the accessory system (water pump , alternator and p/s if you have a Beetle). Adding a supercharger to this secondary belt system will add additional load to the A/C and cause probable failure to the unit or even cause extreme belt slippage. Not to mention it takes HP to rotate a supercharger rather then running off spent exhaust gas so you are actually "wasting" hp.After weighing the pros and cons and seeing how to implement a kit , the choice was made towards turbocharged.

*Turbocharged:*
As Keith has stated , it is very much possible with today's turbo technology to get supercharger like performance . Just choose the right turbocharger.
_PROS OF GOING TURBO:_


No need for a cast intake manifold
No worry of how serpentine accessories will be affected
Can use oem downpipes
will be completely OEM looking


I think as time goes on and more of these vehicles end up in enthusiast hands , we will be seeing alot of forced induced projects popping up. :biggrinsanta:


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## ~kInG~ (Jun 8, 2005)

Issam,

Around what turbocharger are you developing the kit?


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## nothing-leaves-stock (Mar 1, 2005)

issam,
you are correct on the A/C belt issue and we have spec'd out the rotrex unit for our "setup".
but we figured out a way to run the SC without touching the other assy ont hte original belt setup 
all we need is a willing 2.5L customer to step up and we will built it. we just sold our 2.5L car....so no more testing on that


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## lessthanalex (Oct 12, 2009)

Josh, I've mentioned it before and I'll say it again, if I find the money somewhere, I'll be in to see you in a flash for an SC kit.


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## Issam Abed (Feb 12, 2004)

~kInG~ said:


> Issam,
> 
> Around what turbocharger are you developing the kit?


3076R with a 1 bar wastegate.
That will really help given the volume of displacement this motor has. We will not be developing a kit based on Journal bearings nor will we be offering components of the kit for sale.


nothing-leaves-stock said:


> issam,
> you are correct on the A/C belt issue and we have spec'd out the rotrex unit for our "setup".
> but we figured out a way to run the SC without touching the other assy ont hte original belt setup
> all we need is a willing 2.5L customer to step up and we will built it. we just sold our 2.5L car....so no more testing on that


Thought about going through the rear of the motor too and running a separate pulley off the crankshaft pulley but after lazer cutting brackets , and running accessory pulleys / idlers , the cost raises up to the point where you might as well go turbo.
A Rotrex unit is 2250 USD by itself....no billet compressor wheel and the only candidate I would use hardly gives a 28RS a run for its money.


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## ~kInG~ (Jun 8, 2005)

Issam Abed said:


> 3076R with a 1 bar wastegate.
> That will really help given the volume of displacement this motor has. We will not be developing a kit based on Journal bearings nor will we be offering components of the kit for sale.


:thumbup::thumbup:

Just wanted to confirm if the 3076 was the best unit for this engine!


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## stangg172006 (Jul 21, 2006)

Turbo... way more flexible...


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## nothing-leaves-stock (Mar 1, 2005)

issam,
the cost would be about the same as a turbo from what we figured. BUT then again we didn't finish one yet, so changes could happen in prices. never know till its done and perfect.

we were thinking that the rotrex would be comparable to the turbo kit in power. but as always, sc get beat by turbo in the crazy hp game....but for a stg1 or 2...i think we'd be in the same ball park just with differnt drivability feature.

yes no?


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## Issam Abed (Feb 12, 2004)

nothing-leaves-stock said:


> issam,
> the cost would be about the same as a turbo from what we figured. BUT then again we didn't finish one yet, so changes could happen in prices. never know till its done and perfect.
> 
> we were thinking that the rotrex would be comparable to the turbo kit in power. but as always, sc get beat by turbo in the crazy hp game....but for a stg1 or 2...i think we'd be in the same ball park just with differnt drivability feature.
> ...


 You are correct that the S/C would be very much in the same ball park range but the unit itself costs $2200 USD.
Then you need brackets etc etc:thumbdown:


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## nothing-leaves-stock (Mar 1, 2005)

when we priced it out with making everything, tune and software...we would be about only $100 more then a turbo kit thats out now.


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## 4enjunk (Oct 7, 2010)

The flexibility of turbochargers is where it's at. Where can you get so many choices that are direct bolt-ons? Once you have the manifold and plumbing fabricated- pick a turbo, any turbo! The load on the motor isn't all that good either. I'd rather a little back pressure than more load on my crank. I like that when I let someone use my car, I can simply turn the boost down to a level where they won't get scared and kill someone. When I go to the track I can crank the boost up to the edge of it's efficiency range. It becomes a completely different animal with just the turn of a screw. Considering also the proprietary design of superchargers, turbochargers are simply the most logical choice.


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## kevin splits (Aug 23, 2010)

4enjunk said:


> The flexibility of turbochargers is where it's at. Where can you get so many choices that are direct bolt-ons? Once you have the manifold and plumbing fabricated- pick a turbo, any turbo! The load on the motor isn't all that good either. I'd rather a little back pressure than more load on my crank. I like that when I let someone use my car, I can simply turn the boost down to a level where they won't get scared and kill someone. When I go to the track I can crank the boost up to the edge of it's efficiency range. It becomes a completely different animal with just the turn of a screw. Considering also the proprietary design of superchargers, turbochargers are simply the most logical choice.


more back pressure than load on your crank  lol had to do it eace:


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## BlackRabbit2point5 (Sep 6, 2007)

kevin FaKiN spLits said:


> how bout 2.5tc(twincharged):laugh: like the motor the euro mkv golf gt has, but the 5 cylinder twincharged would be kinda cool.. a little much but cool :thumbup:


see the Hellion twin turbo kits for the GT500 to see why twin charging is a terrible idea (removing the supercharger yeilds more power)... to keep it short the supercharger causes a major bottleneck and all the extra parts means your car would most likely never run reliably. On a small displacement OEM application like the 1.4TSI its not a horrible idea because its OEM engineering and not shooting for huge power.


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## turbomonkeyexpress (Nov 26, 2004)

What's the overall cost look like total for a supercharger, and power output?


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## Issam Abed (Feb 12, 2004)

Sorry to disappoint but now that these cars are getting more affordable Turbocharging is happening


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