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Old 12-26-2009, 07:22 PM   #1
dmcutter
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Default VF39 vs HTA68 vs Blouch TD0518G 8 cm

I've read endless threads on all of these, of course, including all 51 pages of the HTA vs 16G post, so this question is not being posed without considerable research.

I have an 06 WRX 4EAT with a VF39, Cobb catted dp (wrapped), TXS tmic, various silicone hoses, and a drop in panel filter. E tune by Clark Turner, running about 17 psi. I had a Borla Hush but my wife whined about how loud it was, so I went back to the stock cbe. Either that or be damned to an eternity of making all our trips in her CRV. This is my daily driver. I will probly never take it to the strip, may eventually track it since I'm only an hour from VIR. I live for twisty roads, though, paved or otherwise. Big hp numbers are great, yeah, everyone wants them, but honestly I don't care so much about power at redline as torque in the lower and mid range.

So here's the question. For the best low end response and daily drivability, which of the 3 is the best? I know that the 39 and 68 are hobbled at the top end by the 7 cm hot side, but most everything I read says the 68 spools crazy fast. I have also read that much higher boost and more mods, e.g. headers, are necessary to really wake the 68 up. What I like best that I've seen about the Blouch 18G is that it feels like driving a V8 and makes better power with lower boost. I am willing to do some more supporting mods (bigger injectors, of course) like a short ram intake if it helps, but I don't want the noise of an EWG and want to stay with the stock CBE.

Within those constraints, what's the best bet?
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Old 12-27-2009, 06:34 AM   #2
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depend..do you do your own wrenching?
turbo..either 68 or 18g..but you will need more injector
for either turbo...
header on either turbo will delay spool abit..
but you will gain more power after you go catless tbe..
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Old 12-27-2009, 04:04 PM   #3
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cant go wrong with either one, really. Go with what you find the deal on. Maybe even consider going a little unconventional with a 8cm 16g?
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Old 12-28-2009, 12:55 PM   #4
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My vote would be a Blouch TD05H-18G 8cm. The 8cm is a must on a 2.5L, it is a blast to drive, and has power EVERYWHERE. I love mine. I made 320whp/294ft-lbs at only 16PSI. IMHO it is the perfect size turbo for a daily driven 2.5L WRX.

LOL, my GF complains that my Borla Hush is a bit loud too. I just tell her be happy it is not a Blitz nur spec.

Last edited by csmithwrx'05; 12-28-2009 at 01:00 PM.
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Old 12-28-2009, 01:01 PM   #5
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Good info. Do you have a dyno curve? What other mods are you running? Seems like the 39 makes the best torque of the bunch, though. I've seen a lot of 310-330 ft-lb curves, thought peak hp is down.
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Old 12-28-2009, 01:06 PM   #6
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I would stick with the vf39... the other turbos really aren't that much bigger than what you got.
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Old 12-28-2009, 01:09 PM   #7
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I'm starting to read up on alcohol injection. Seems like that might be a reasonably cost effective way to maximize what I have now. Or I could just leave it the hell alone and improve the suspension, which is really what limits it on twisty roads, anyway.
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Old 12-28-2009, 01:58 PM   #8
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Add the alky (and tune of course) and see if you are happy. If you are, then you are set. If not, you can still use it to make even more power whenever you get around to your future upgrade!
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Old 12-28-2009, 02:32 PM   #9
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Quote:
Originally Posted by subenerd View Post
I would stick with the vf39... the other turbos really aren't that much bigger than what you got.
LOL! You're a funny little man
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Old 12-28-2009, 03:31 PM   #10
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Originally Posted by dmcutter View Post
Good info. Do you have a dyno curve? What other mods are you running? Seems like the 39 makes the best torque of the bunch, though. I've seen a lot of 310-330 ft-lb curves, thought peak hp is down.
I sure do. My torque numbers are down b/c I am only at 16PSI (also using the stock BCS) and not really even in the efficiency range of my turbo. My tuner and I were just shooting for 300whp and when it hit 320whp at 16PSI we stopped for my weaka$$ 5-speed tranny's sake. But, according my my tuner she has PLENTY power left and I would have a considerable increase in torque once the boost is upped to 18PSI or more.

Here is a link in my original build thread with dynochart:

http://forums.nasioc.com/forums/show....php?t=1598649
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Old 12-28-2009, 03:47 PM   #11
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Thanks for posting that csmith, this is the exact info I was looking for! Next year I am stuck between the cheap route (vf39+perrin tmic) or the proper but expensive route (18gc 8cm + perrin tmic + DW650+ walboro fuel pump etc etc).

Since this was a year ago, how does your tranny feel after going over 300WHP? my WRX is my DD also and I drive fairly conservatively, about 99% of the time. Once in a while after work I open her up but thats maybe once a week. I am afraid of grenading 2nd gear with this 2.5's tq.
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Old 12-28-2009, 03:54 PM   #12
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Originally Posted by d3v0 View Post
Thanks for posting that csmith, this is the exact info I was looking for! Next year I am stuck between the cheap route (vf39+perrin tmic) or the proper but expensive route (18gc 8cm + perrin tmic + DW650+ walboro fuel pump etc etc).

Since this was a year ago, how does your tranny feel after going over 300WHP? my WRX is my DD also and I drive fairly conservatively, about 99% of the time. Once in a while after work I open her up but thats maybe once a week. I am afraid of grenading 2nd gear with this 2.5's tq.
Correct me if I'm wrong but I hear 3rd gear is the weak link for our years. I also have two buddies both running 18g's with supporting mods and they love the damn things. Very nice powerband. I'm however going the vf39 route getting tuned next month so I'll post my impressions.
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Old 12-28-2009, 03:58 PM   #13
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Originally Posted by subenerd View Post
I would stick with the vf39... the other turbos really aren't that much bigger than what you got.


Dear God I hope you're joking.


OP- the 18G-8CM is, by far, the best option, if for no other reason than the 8cm hotside. Better throttle response, better off-boost torque, and an on-par performer with the HTA68, perhaps even better up top.
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Old 12-28-2009, 05:56 PM   #14
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Dear God I hope you're joking.


OP- the 18G-8CM is, by far, the best option, if for no other reason than the 8cm hotside. Better throttle response, better off-boost torque, and an on-par performer with the HTA68, perhaps even better up top.
Well, I have held both in my hand (there isn't much of a size difference) and I have seen 18gs custom tuned in my area, they only make about 20hp more than custom tuned vf39's. If he wants more low end grunt why not just get a custom tune? That will increase spool/torque and top end for way cheaper.

Sure, going from a TD04 to an 18g is a HUGE improvement but honestly I don't see the point in spending all the time/money/effort/tuning into switching to an 18g if he already has a vf39. The vf39 is a great turbo when tuned properly.

My 2 cents.
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Old 12-28-2009, 06:28 PM   #15
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Quote:
Originally Posted by d3v0 View Post
Since this was a year ago, how does your tranny feel after going over 300WHP? my WRX is my DD also and I drive fairly conservatively, about 99% of the time. Once in a while after work I open her up but thats maybe once a week. I am afraid of grenading 2nd gear with this 2.5's tq.
Tranny feels great (a little over 80K miles on it) I changed the tranny fluid to Motul Gear 300 about 2K miles ago and she shifts better than ever. I am still on my stock clutch too (just changed the clutch disc when we did the build).

I drive my car very hard and take it past 7K RPMs (have a 7500RPM limit) almost daliy, as I have a nice 15 minute drive home form work on some great roads. I just don't launch/bang gears like an a$$ and always make sure to fully engage the clutch/shift smoothly and slip the clutch when needed. But, I when/if my tranny goes (or money is not as tight) I will upgrade to a 6-speed or some form of upgraded 5-speed gears (i.e. PPG, DS1, etc.).

FYI...If I had to do it over again the only thing I would do differently is going bigger on the injectors, so I could run e85 b/c 650ccs will run out of flow way too quick for e85 (prolly get some DW850s just to make sure). But, at the time I did not even know e85 existed..LOL.

Last edited by csmithwrx'05; 12-28-2009 at 06:43 PM.
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Old 12-28-2009, 06:41 PM   #16
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Quote:
Originally Posted by subenerd View Post
Well, I have held both in my hand (there isn't much of a size difference)[...]
The Blouch 18G has a TD06 compressor cover. It's significantly bigger than whatever compressor cover is on the VF39.
Unfortunately, most people go out there and buy the "small" 18g with a TD05 compressor cover which is simply a TD05H-16G with a 18G compressor wheel stuffed in it.
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Old 12-28-2009, 07:16 PM   #17
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Also from what I've read the 18G with an 8cm hotside is critical on the 2.5; I don't know how the VF39 compares...
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Old 12-28-2009, 07:30 PM   #18
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Quote:
Originally Posted by dmcutter View Post
I've read endless threads on all of these, of course, including all 51 pages of the HTA vs 16G post, so this question is not being posed without considerable research.

I have an 06 WRX 4EAT with a VF39, Cobb catted dp (wrapped), TXS tmic, various silicone hoses, and a drop in panel filter. E tune by Clark Turner, running about 17 psi. I had a Borla Hush but my wife whined about how loud it was, so I went back to the stock cbe. Either that or be damned to an eternity of making all our trips in her CRV. This is my daily driver. I will probly never take it to the strip, may eventually track it since I'm only an hour from VIR. I live for twisty roads, though, paved or otherwise. Big hp numbers are great, yeah, everyone wants them, but honestly I don't care so much about power at redline as torque in the lower and mid range.

So here's the question. For the best low end response and daily drivability, which of the 3 is the best? I know that the 39 and 68 are hobbled at the top end by the 7 cm hot side, but most everything I read says the 68 spools crazy fast. I have also read that much higher boost and more mods, e.g. headers, are necessary to really wake the 68 up. What I like best that I've seen about the Blouch 18G is that it feels like driving a V8 and makes better power with lower boost. I am willing to do some more supporting mods (bigger injectors, of course) like a short ram intake if it helps, but I don't want the noise of an EWG and want to stay with the stock CBE.

Within those constraints, what's the best bet?
90% of this is correct. The 18g making the same or more power with less boost is completely incorrect though. THe 68 will hand the 18g8cm its ass on the bottom, and up top, I cant stress this enough.
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Old 12-28-2009, 07:47 PM   #19
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I just purchased the 68HTA since my VF39 took a dump during some highway topend pulls. From what I've seen, it's possible to buy the 8cm turbine housing from FP separately for $295 if the topend feels choked off, so there is some tuneability.
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Old 12-28-2009, 07:51 PM   #20
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Originally Posted by subenerd View Post
Well, I have held both in my hand (there isn't much of a size difference) and I have seen 18gs custom tuned in my area, they only make about 20hp more than custom tuned vf39's. If he wants more low end grunt why not just get a custom tune? That will increase spool/torque and top end for way cheaper.

Sure, going from a TD04 to an 18g is a HUGE improvement but honestly I don't see the point in spending all the time/money/effort/tuning into switching to an 18g if he already has a vf39. The vf39 is a great turbo when tuned properly.

My 2 cents.

You can NOT compare turbos based on their size difference. And an 18G may only make 20 more whp than a VF39, but it makes it just as quickly and holds MUCH better.

Now, my POINT was about the 8cm hotside, not 18g vs. VF39. With the 8cm hotside on ANY turbo, you'll have (as I already said) better throttle response, off-boost torque, and an even larger increase in peak power, which will hold MUCH better up top, while still making it just as quickly as the VF39.
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Old 12-28-2009, 08:31 PM   #21
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You can NOT compare turbos based on their size difference. And an 18G may only make 20 more whp than a VF39, but it makes it just as quickly and holds MUCH better.

Now, my POINT was about the 8cm hotside, not 18g vs. VF39. With the 8cm hotside on ANY turbo, you'll have (as I already said) better throttle response, off-boost torque, and an even larger increase in peak power, which will hold MUCH better up top, while still making it just as quickly as the VF39.
Your right, its simple physics when considering the 8cm hotside. But you know as well as I, sometimes physics, for some reason doesnt apply.

When is the last time you saw a, 18G on an SAE corrected dynojet make 415whp and hold 400 at redline.. Never. I didnt even lean into my 68 and it made 30 more whp than when my vf was maxed out throwing me to 12.0's down the 1/4. Its capable of getting DEEEP into the 11's in a relatively stock form car (Im not talking Xdrian type 18G stuff where the car weighed 2600 and had ppg's).
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Old 12-28-2009, 08:57 PM   #22
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See, now this is what I was hoping for when I posted. How come it took the heavy hitters so long to weigh in?

And Mikey, you're an engineer. We know that physics ALWAYS applies!
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Old 12-28-2009, 09:15 PM   #23
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Originally Posted by dmcutter View Post
See, now this is what I was hoping for when I posted. How come it took the heavy hitters so long to weigh in?

And Mikey, you're an engineer. We know that physics ALWAYS applies!

Haha, yes, I know. What I am implying is that even at 27-28 Psi, I havnt seen the 7cm hotside take its toll on this turbo up top.





On the E85 tune it fell off a little, but they also talk about more timing and more boost for the future and that 430 falling to 400 isnt out of the question. The slight inconsistencies are the stock 2 litre SCREAMING for life, lol.
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Old 12-28-2009, 09:47 PM   #24
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Originally Posted by csmithwrx'05 View Post
Tranny feels great (a little over 80K miles on it) I changed the tranny fluid to Motul Gear 300 about 2K miles ago and she shifts better than ever. I am still on my stock clutch too (just changed the clutch disc when we did the build).

I drive my car very hard and take it past 7K RPMs (have a 7500RPM limit) almost daliy, as I have a nice 15 minute drive home form work on some great roads. I just don't launch/bang gears like an a$$ and always make sure to fully engage the clutch/shift smoothly and slip the clutch when needed. But, I when/if my tranny goes (or money is not as tight) I will upgrade to a 6-speed or some form of upgraded 5-speed gears (i.e. PPG, DS1, etc.).

FYI...If I had to do it over again the only thing I would do differently is going bigger on the injectors, so I could run e85 b/c 650ccs will run out of flow way too quick for e85 (prolly get some DW850s just to make sure). But, at the time I did not even know e85 existed..LOL.
Closest E85 is about half a gas tank away for me doing the math....probably looking at DW650s

My tranny has 85k on it currently. I dont load the engine much w/ high speeds, but I do run through 1-3 WOT on occasion (not racing as this is bog launched haha, I need to remind myself why I spend so much on this car) I ease nicely into second to help with driveline shock but I am also on a Stage 2 Cobb TD04 haha, making ~240-50WHP tops.

I like the 5 speed. I am going to look into PPG in the future, quite possibly before the 18g.
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Old 12-28-2009, 10:18 PM   #25
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Quote:
Originally Posted by STi Mikey View Post
Your right, its simple physics when considering the 8cm hotside. But you know as well as I, sometimes physics, for some reason doesnt apply.

When is the last time you saw a, 18G on an SAE corrected dynojet make 415whp and hold 400 at redline.. Never. I didnt even lean into my 68 and it made 30 more whp than when my vf was maxed out throwing me to 12.0's down the 1/4. Its capable of getting DEEEP into the 11's in a relatively stock form car (Im not talking Xdrian type 18G stuff where the car weighed 2600 and had ppg's).

Ah, yes, I agree. HOWEVER, the benefits of an 8cm over a 7cm on a 2.5 are more than just numbers and hypotheticals on paper.

Xdrian ran an 18G into the 10s if I recall, and a VF39 hasn't gotten within a half second. But we all know that the difference in numbers and output alone did not make that difference. the PEAK numbers won't be drastically different from VF39 to 18G-8cm. What WILL be drastically different is the fatness of the powerband and, even more drastic, the improvement in driveability. And that's the point I'm making.

My argument is NOT based on better performance numbers, but rather the improvement in driveability and fatter powerband. Would you agree, even apples-apples, that better driveability and fatter powerband make for a better setup even with the same numbers or track times?

That's all I'm saying, but the icing on the cake is the improved numbers...
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