Opinions needed about the k24 turbochargers

[FabS6]

Hi everyone,

I have a 1996 c4 S6 saloon with: 5spd gb, gutted cats, equal-lenght runners tubular exhaust manifold and screamer pipe, stock intercooler with a fan (water-air IC on my plans), 2.5 bar map stock, k24-7000 with ported and polished compressor housing, 1.5bar max boos and motronic launch control. and the car is with almost no extras...it's pretty light indeed. No idea about my 400mt ET yet...factory clutch yet.


Since I am not planning to upgrade my rods yet and want a fun street car with the least lag possible I have three turbo options and inside the k24 family. Unfortuntely the RS2's has too much lag yet, too expensive and too rare.

What do you think about that Volvo 7400 turbocharger? also with a billet wheel foundable at ardideas.com or leave it stock.

OR... what about stay with the cheapy 7000 easy to find with some mods like:
-Ported and polished compressor housing (done on mine)
-11+0 blade billet wheel with extended tip tech for more high-rpm flow
-Clipping a bit the turbine blades
-Porting the turbine housing

I want max safe torque, stay within 330-350bhp powerband and a fast car for long trips. I'd like to know what would you do in my case mates, also interested to know PRJ, PAUL and JAMO's opinions knowing they wide experience tuning these engines with every kind of upgrade.

Thanks!


PS.: further info: I'm not planning to change rods yet (only in the case I need to rebuild my engine due to high mileage), it has 152,000km, timing belt changed once (will change it next month again). Castrol Edge 10w-60 oil changed every Spring since i don't do more than 4-5000km a year, new sparkplugs and boots changed 6000km ago. Basically these are my car's engine conditions.

[Vorsprung durch Technik]

Hi everyone,

Since I am not planning to upgrade my rods yet and want a fun street car with the least lag possible I have three turbo options and inside the k24 family. Unfortuntely the RS2's has too much lag yet, too expensive and too rare.

What do you think about that Volvo 7400 turbocharger? also with a billet wheel foundable at ardideas.com or leave it stock.

I want max safe torque, stay within 330-350bhp powerband and a fast car for long trips. I'd like to know what would you do in my case mates, also interested to know PRJ, PAUL and JAMO's opinions knowing they wide experience tuning these engines with every kind of upgrade.

Thanks!


.

Hi FabS6, considering what you have written quoted above and want to limit BHP to 330-350 i would say you have chosen an ideal turbo in the Volvo 7400 and quite a bit has been written up on it.Its a better turbo than stock S6. It doesn't get chosen by many because it's not a sexy enough turbo as it seams most on here are looking for 400BHP plus. What i like about the Volvo 7400 is it's super quick spool will give you better than stock RS2 power and virtually no lag. Whats not to like about this turbo This would be a really great everyday day car if you fitted the Volvo 7400 and you wouldn't regret it given your requirements and what you have said above.

Quick question have you seen Biryd's and Ruffiano's thread on the Volvo 7400? Makes very good reading to me anyway!

Good luck with it.

Heres a link to a recent one that came up.

http://www.s2forum.com/forum/showthread.php?t=73700

[S2central.net]

I also think the Volvo 7400 is a nice way to go if you aren't looking for 400bhp and beyond. I have only done the one but it didn't have much lag to speak of and blew quite nicely. You need RS2 or bigger injectors of course if staying on 4bar FPR. The one I did was all bolt on - no fancy porting / polishing but a decent exhaust is highly recommended.

Fwiw - I wouldn't waste time on water : air cooler - there are proven ways to run FMIC on the UrS4/S6 without getting into drastic bumper mods.

[S2central.net]

I also think the Volvo 7400 is a nice way to go if you aren't looking for 400bhp and beyond. I have only done the one but it didn't have much lag to speak of and blew quite nicely. You need RS2 or bigger injectors of course if staying on 4bar FPR. The one I did was all bolt on - no fancy porting / polishing but a decent exhaust is highly recommended.

Fwiw - I wouldn't waste time on water : air cooler - there are proven ways to run FMIC on the UrS4/S6 without getting into drastic bumper mods.

[FabS6]

Hi FabS6, considering what you have written quoted above and want to limit BHP to 330-350 i would say you have chosen an ideal turbo in the Volvo 7400 and quite a bit has been written up on it.Its a better turbo than stock S6. It doesn't get chosen by many because it's not a sexy enough turbo as it seams most on here are looking for 400BHP plus. What i like about the Volvo 7400 is it's super quick spool will give you better than stock RS2 power and virtually no lag. Whats not to like about this turbo This would be a really great everyday day car if you fitted the Volvo 7400 and you wouldn't regret it given your requirements and what you have said above.

Quick question have you seen Biryd's and Ruffiano's thread on the Volvo 7400? Makes very good reading to me anyway!

Good luck with it.

Heres a link to a recent one that came up.

http://www.s2forum.com/forum/showthread.php?t=73700

Yes mate I have read those threads too and been following them since a pair of years ago. Always been curious about that 7400 and it's newer tech! Hope to find one at a reasonable price as soon as I have that money to spend in my hands hehe

I also think the Volvo 7400 is a nice way to go if you aren't looking for 400bhp and beyond. I have only done the one but it didn't have much lag to speak of and blew quite nicely. You need RS2 or bigger injectors of course if staying on 4bar FPR. The one I did was all bolt on - no fancy porting / polishing but a decent exhaust is highly recommended.

Fwiw - I wouldn't waste time on water : air cooler - there are proven ways to run FMIC on the UrS4/S6 without getting into drastic bumper mods.

Thank you Paul! I think will follow your suggestions. About the fmic not sure yet as I don't like the looks of a fancy intercooler in the front...want to stay as much oem look as possible (I love to have a sleeper). Another question... may I upgrade my map to a 3bar one too?

[UrS4boy]

One option that has been used over here with good success on an AAN is the KKK K26/Garrett GT2871 hybrid turbo that 034 sells. Less lag than a K24-7200 RS2 turbo and more hp than the stock AAN K24-7000 (with the appropriate injectors and software)

http://store.034motorsport.com/k26-gt2871-turbocharger-20843.html

[Vorsprung durch Technik]

Hi everyone,
What do you think about that Volvo 7400 turbocharger? also with a billet wheel foundable at ardideas.com or leave it stock.

Thanks!

I don't know the answer to this question FabS6 but i am very interested to know what the advantage of a billet wheel might be too. I now have the Volvo K7400 turbo with the porsche K26/6 hotside but as ever its all money so progress will be slow. Are you going to Flow and port match the head? I am thinking about it long term as a flowed and ported head along with a well matched exhaust has got to add another 30 BHP to compliment further the k7400. K7400 + Extractor manifold/exhaust + flowed and ported head in my eyes should be an awesome set up. What do you think?

[S2central.net]

Yes mate I have read those threads too and been following them since a pair of years ago. Always been curious about that 7400 and it's newer tech! Hope to find one at a reasonable price as soon as I have that money to spend in my hands hehe

Thank you Paul! I think will follow your suggestions. About the fmic not sure yet as I don't like the looks of a fancy intercooler in the front...want to stay as much oem look as possible (I love to have a sleeper). Another question... may I upgrade my map to a 3bar one too?

Yes - they blow to about 1.7bar max so a 3bar MAP sensor is the way to go.

[andy10v]

i am very interested to know what the advantage of a billet wheel might be too.

Billet wheels are lighter, this is true. The cone in the middle of compressor wheel is significantly smaller in modern billet wheel designs than in the cast opponents of same dimensions. Hence they have more flow area, and obviously more flow capacity. IOW if cast and billet wheels same dimensions, billet wheel has longer blades.

Less lag if lighter, more flow for the same size.

There is discussion on billet RS2/K26s Iroz offers here

http://www.s2forum.com/forum/showthread.php?t=57883&highlight=billet

I dont think you would get quite the same flow gains, as a k24 7400 has a much more modern compressor than the k24 7000 (90s tech v 2006? tech) But still should be an improvement.

[FabS6]

One option that has been used over here with good success on an AAN is the KKK K26/Garrett GT2871 hybrid turbo that 034 sells. Less lag than a K24-7200 RS2 turbo and more hp than the stock AAN K24-7000 (with the appropriate injectors and software)

Well mate, you see...I prefer to stay with KKK. Garrett offers a super technology but very low durability if we make a comparisson with KKK which lasts really a lot, and there is the need to work on the cartridge adaptation and the ballbearing tuning difficulties to go through.

I don't know the answer to this question FabS6 but i am very interested to know what the advantage of a billet wheel might be too. I now have the Volvo K7400 turbo with the porsche K26/6 hotside but as ever its all money so progress will be slow. Are you going to Flow and port match the head? I am thinking about it long term as a flowed and ported head along with a well matched exhaust has got to add another 30 BHP to compliment further the k7400. K7400 + Extractor manifold/exhaust + flowed and ported head in my eyes should be an awesome set up. What do you think?

It sounds pretty good mate. I wont open my engine untill I have my engine rebuild yet untill I have some wear problems that needs an engine rebuild (I still have less than 100K miles so the engine is still in great conditions). Hope to find a nice 7400 soon or later at a reasonable price! Then look for some 400cc injectors, K26/#6 turbine housing, 3bar map and some nice mufflers to replace the silencers.

Yes - they blow to about 1.7bar max so a 3bar MAP sensor is the way to go.

Got it Paul, I'll try to get all the bits little by little and then look for the chipsets fro the motronic, hopefully with launch controll included.

Less lag if lighter, more flow for the same size.
There is discussion on billet RS2/K26s Iroz offers here

http://www.s2forum.com/forum/showthread.php?t=57883&highlight=billet

I dont think you would get quite the same flow gains, as a k24 7400 has a much more modern compressor than the k24 7000 (90s tech v 2006? tech) But still should be an improvement.

Yeah mate, I've been looking that thread too, but the volvo seems to be the best choice for me as the RS2 has that expensive price+too rare to find, and that iroz-k26billet offers a great bhp peak but torque comes too late. A k2474 has virtually no lag at all, then add a billet wheel...it would be a great little turbo.

You know why am I looking for the best bottom end torque? This car is only used for long trips I do once in a while, I even was thinking to get the AAT (c4 tdi 116bhp 6spd 4,111:1) gearbox with that long 6th gear to cruise at low revs and good torque to maintain the speed without stellar fuel consumption of the higher rpm...but having a strong engine to make it a real sleeper.

[Quattronaut]

Especially for high torque in low rpms upgraded rods should be used... so be carefull with that bottom power, still those little turbis can crack the rods without reaching 350hp.

The 7400 turbos are quite good in spool an power, but they only have 270° bearings, which limits reliability at high pressure- with a stock one, 1,7bar are quite much and should be reached only a very short time- better to think about upgrading to 360° bearing for reliability and still bit more performance.

Another posibility is to upgrade the stock S6 turbo with the comp wheel from the TTRS- a very simple and cheap mod for around 330hp and good spool. Or take the same comp wheel, another turbine wheel, 360° bearing and you have a stock looking and usable turrbo that can do reliable 350-360 hp and 500 nm.

[mouse]

Less lag if lighter, more flow for the same size.

There is discussion on billet RS2/K26s Iroz offers here

http://www.s2forum.com/forum/showthread.php?t=57883&highlight=billet

I dont think you would get quite the same flow gains, as a k24 7400 has a much more modern compressor than the k24 7000 (90s tech v 2006? tech) But still should be an improvement.

It will be interesting to see where iroz are going with the below comment from the same thread:

....
We have a really neat k24 billet coming out that should actually make the rs2 billets obsolete FYI. It is in testing and is again playing on the theory that a #6 hotside(or .42AR in garrett terms) can only do so much work, so why overload teh assembiles with bigger wheels to get marginal gains in the name of lag?

[Rusty]

The IROZ K24 that's in development will suit your needs perfectly OR there's a 2871 for sale on here at present.

Running an RS2 setup, lag is as much about the map as the turbo. Stock RS2 map is pretty slow to boost whereas my remap is much faster.

Although you may think you want 330, aim for 350 and you'll be happy

[mouse]

Must be this one:

http://forums.quattroworld.com/s4s6/msgs/298218.phtml

Early testing shows almost 70whp(!) gains with identical spool...should be a fantastic option for daily drivers
https://youtube.com/watch?v=bwrDUkwiJ1k

[FabS6]

Especially for high torque in low rpms upgraded rods should be used... so be carefull with that bottom power, still those little turbis can crack the rods without reaching 350hp.
The 7400 turbos are quite good in spool an power, but they only have 270° bearings, which limits reliability at high pressure- with a stock one, 1,7bar are quite much and should be reached only a very short time- better to think about upgrading to 360° bearing for reliability and still bit more performance.
Another posibility is to upgrade the stock S6 turbo with the comp wheel from the TTRS- a very simple and cheap mod for around 330hp and good spool. Or take the same comp wheel, another turbine wheel, 360° bearing and you have a stock looking and usable turrbo that can do reliable 350-360 hp and 500 nm.

Yes I have read the remapped s60R's blow the turbos easily and they chose the MHI 18G for it's high boost setups.
I feel some curiosity about that TTRS compressor wheel mate... any idea where can I get one?

It will be interesting to see where iroz are going with the below comment from the same thread:

The IROZ K24 that's in development will suit your needs perfectly OR there's a 2871 for sale on here at present.
Running an RS2 setup, lag is as much about the map as the turbo. Stock RS2 map is pretty slow to boost whereas my remap is much faster.
Although you may think you want 330, aim for 350 and you'll be happy

well yes Andy, the more bhp, the better....I just want to avoid that horrible lag to have a more fun car to drive and without going over the rod's strenght limit

Must be this one:
http://forums.quattroworld.com/s4s6/msgs/298218.phtml

And.... I like pretty much the idea with a billet wheel on the 7000, maybe a single blade with extended tip for increased flow at high rpm. Wanted to order one to KTS but they only sell them in the 6+6 design (good torque and spool but poor high rpm flow) and there was a minimum units to buy.

I like pretty much the 7000 for various reasons and will take a 7400 only in the case the 7000 wouldn't be enough after upgrading it. Having the tubular EM and the ported and polished compressor housing is enough to feel the difference on how it maintains and delivers the boost than stock and I do not get less than 2.0bar absolute at the redline....before I could see 1.8 or 1.9 maximum.

Now I have 3 options:
- K2474
- TTRS compressor wheel (billet?)
- maybe Iroz's billet for the 7000? I feel very curious about it!!!