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Old 01-18-2007, 05:33 PM   #1
oversteer
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Default Turbo talk - TD06-18G vs TD05-20G - experts inside please

Over the past few months the subject of mid sized turbo upgrades has been beaten to death on the 2.5L section of this forum but even after reading over all of the posts I feel there is still some vital information missing.

Many of us are looking for a nice little bump over the VF39 without introducing more lag or slow boost response into the picture while still being able to retain the stock MAF for ease of tuning. To qualify what we want I would say at least 300whp on a Mustang and at least 330whp on a Dynojet with 91 or 92 octane fuel. This is to say about 10% + more power than a well tuned STi with the stock turbo since these are often around 300whp. Naturally all the supporting mods would be present to reach this power goal.

After reading over all the posts I can find and some mid level turbo tech FAQs I am still left wondering what the best turbo is but I know that an FP Green would be the upper size limit and is probably even too big for my needs. Let's try to avoid having this thread go OT with people suggesting that GT30s and FP Reds are fine for daily combos since this is not where some of us want to be. If I wanted to beat Z06s in the 1/4 I would just go buy a Z06.

The two turbos that keep coming up are various combinations of the 18G and 20G turbos combined with the 8cm exhaust housing to avoid creep with the IWG. Can one of the resident turbo experts please explain the technical and real world differences and consequences of going with the smaller compressor (18G) and larger exhaust wheel (TD06) vs the larger compressor (20G) and smaller exhaust wheel (TD05)?

I have never understood which side of the turbo has a larger effect on the spool up time and boost response feel but my gut feeling is that of the two the TD05-20G would spool faster but have more exhaust back pressure at high boost/rpm and the TD06-18G would spool a bit slower but with less back pressure at high boost/rpm. Is it possible that although there are technical differences between these two turbos they would actually feel the same to drive and make about equal dyno numbers on the same fuel?

Whew...that should just about cover it
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Old 01-18-2007, 05:34 PM   #2
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Here is a good post I found but it doesn't address the different sized compressor sides.

Quote:
The TD05-20G (7cm) spools very similar to the stock turbo, will made about 40more ft/lbs in the midrange and 20whp up top. It's very responsive as it's a small turbine, small turbine wheel. The TD06-20G on the other hand is worth about 40whp up top about 40ft/lbs in the midrange, but is a bit laggier and less responsive than the TD05-20G.

In my opinion the TD05-20G is great if you're looking for pure midrange, while the TD06-20G makes a lot more power up top (especially with good gas) if you're willing to put up with a bit more lag and a bit slower response (actually I'd consider the RR500 or FP Green for the money).

Cheers,

Gary
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Old 01-19-2007, 02:58 PM   #3
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Lots of views and no replies Was my question too far out there?
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Old 01-19-2007, 03:34 PM   #4
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Most of those threads you read suck because 90% of the posts contained within are something the effect of "go big or go home" or "get a GT35R, lag is overrated" or "not enough top end gain, not worth the money."

Thanks for the effort! I'm curious to see what is said about this.
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Old 01-19-2007, 03:52 PM   #5
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I also want to find more quality info about a "mid-level" turbo upgrade. Just like the poster at the top said a TD06-18 and a TD05-20G with 7cm or 8cm exhaust housing. The TD05-20G with an 8cm exhaust housing is a very intriguing combo and I would love to see more data on this setup. Would the 8cm kill any spoolup/response advantage that the TD05 wheel gives the 20G at the expense of increased top end? Or would you still get turbo that spools quicker then the TD06 wheel with close to or similar top end? I know the 8cm is suppose to help with creep issues. So that is a plus.
These are big questions for me.
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Old 01-19-2007, 04:08 PM   #6
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Hey Mykl & darkcrystal05 thanks for getting involved here.

I don't want to complicate this thread too much but I probably should have included the VF30/34 and VF22 in this discussion. AFAIK these there versions of the VF turbos should be able to make at least as much power as an 18G so maybe they should be considered in this discussion

It looks like the large VF turbos (VF22/VF34) might be about the same size and output as a TD05-18G. Which will spool and respond fastest?

Last edited by oversteer; 01-19-2007 at 04:31 PM. Reason: .
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Old 01-19-2007, 05:35 PM   #7
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I figured someone would love to impress everyone with their vast turbo knowledge so that those of us who are not as well versed in turbo maps would gain some good insight. Good thread, exactly the type of information I would love to hear some qualified opinions on.
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Old 01-19-2007, 06:34 PM   #8
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Quote:
Originally Posted by oversteer View Post
It looks like the large VF turbos (VF22/VF34) might be about the same size and output as a TD05-18G. Which will spool and respond fastest?
From my limited internet knowledge, the 18G is a 40lb/hr wheel and the VF22 is a 35 lb/hr. Also, the VF34 will spool quicker than the 22 due to the ball bearing center section. From what I understand, a TD0518G will spool similar to stock (VF39), maybe giving up 100-200 rpm's.
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Old 01-20-2007, 01:18 AM   #9
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Quote:
Originally Posted by cwepruk View Post
From my limited internet knowledge, the 18G is a 40lb/hr wheel and the VF22 is a 35 lb/hr. Also, the VF34 will spool quicker than the 22 due to the ball bearing center section. From what I understand, a TD0518G will spool similar to stock (VF39), maybe giving up 100-200 rpm's.

What you are saying about the VF34 vs VF22 is similar to what I've read.

It would be great if the TD05-18G spooled and responded almost the same as a VF39 but it is hard to believe without experiencing it firsthand.

Can everyone agree that a TD05 hotside is larger than that of a VF39? Many poster have said that TD05s are too small for our 2.5L engines, but if they are larger than a VF39 then...

Last edited by oversteer; 01-20-2007 at 03:56 PM. Reason: ..
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Old 01-20-2007, 11:22 PM   #10
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Quote:
Originally Posted by oversteer View Post
Can everyone agree that a TD05 hotside is larger than that of a VF39? Many poster have said that TD05s are too small for our 2.5L engines, but if they are larger than a VF39 then...

From what I have been told, the 7cm^2 Mitsu hot side is indeed larger than the VF39's P18 hot side. If I can ever save up enough $, I will be trying a td05h 20g with 7cm^2 hot side with an external wastegate and a reversed intake manifold/FMIC setup.
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Old 01-21-2007, 08:53 PM   #11
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Quote:
Originally Posted by oversteer View Post
The two turbos that keep coming up are various combinations of the 18G and 20G turbos combined with the 8cm exhaust housing to avoid creep with the IWG. Can one of the resident turbo experts please explain the technical and real world differences and consequences of going with the smaller compressor (18G) and larger exhaust wheel (TD06) vs the larger compressor (20G) and smaller exhaust wheel (TD05)?

I have never understood which side of the turbo has a larger effect on the spool up time and boost response feel but my gut feeling is that of the two the TD05-20G would spool faster but have more exhaust back pressure at high boost/rpm and the TD06-18G would spool a bit slower but with less back pressure at high boost/rpm. Is it possible that although there are technical differences between these two turbos they would actually feel the same to drive and make about equal dyno numbers on the same fuel?
The A/R ratio will have a big impact on the lag of the turbo. If you go with an 8cm (about .63 A/R), you are going to have some lag with extra power up top. In my view, the TD05 is too small for the 8cm housing, with the TD05 spooling later because of the A/R and limiting you at the top end. So I'd say a TD06 - 18g or 20g would be best with the 8cm housing. I'd be skeptical of an 8cm TD05-20g. I'd worry the higher A/R would spool later and the TD05 would choke the high end creating a limited power band.

On the other hand, if you have a 7cm housing, then the TD05 and TD06 are both nice matches. In that case, the TD06-18g and TD05-20g would most likely be pretty similar. I agree that the TD05-20g would most likely spool faster between those two, as the weight difference in the compressor wheel (18g vs 20g) would probably have less impact than the difference in the exhaust wheel (05 vs 06).

Just my two cents. I am in no way an expert - just an old guy who has been around turbos for a while. Everything I said is theoretical conjecture, not real empirical data. The best way is to find someone who has tested the setups. After all, "there are more things in heaven and earth than dreamt of in your philosophy". Bump for others who know more than I.
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Old 01-22-2007, 05:18 AM   #12
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TD05H-18G with 8cm^2 housing
or TD06-20G with 7 or 8cm^2...
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Old 01-24-2007, 12:17 AM   #13
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Quote:
Originally Posted by WRX_UA View Post
TD05H-18G with 8cm^2 housing
or TD06-20G with 7 or 8cm^2...
Thank you for the post but a bit of additional information as to why these are the best options would be great appreciated

My thread hasn't generated the type of tech filled posts I was hoping for. Where are all the turbo experts when you need them Oh yeah, probably somewhere out there playing with GT35Rs

Back to my original question...please explain the technical and real world differences and consequences of going with the smaller compressor (18G) and larger exhaust wheel (TD06) vs the larger compressor (20G) and smaller exhaust wheel (TD05)
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Old 01-24-2007, 06:58 AM   #14
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Quote:
Originally Posted by oversteer View Post
Thank you for the post but a bit of additional information as to why these are the best options would be great appreciated

My thread hasn't generated the type of tech filled posts I was hoping for. Where are all the turbo experts when you need them Oh yeah, probably somewhere out there playing with GT35Rs

Back to my original question...please explain the technical and real world differences and consequences of going with the smaller compressor (18G) and larger exhaust wheel (TD06) vs the larger compressor (20G) and smaller exhaust wheel (TD05)
Td06 wheel is too big. Better go Green in this case... Td05h-18g is 300+whp with no lag...
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Old 01-24-2007, 08:35 AM   #15
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Here's my help as I'm in the midst of a highly technical give it hell no kidding watch what you are doing Turbo FAQ article for Subiesport Magazine:

<--fast spool/lower power------slow spool/higher power----->
TD04--------------------TD05----------------------TD06
7cm------------------------------------------------8cm

As to your wheel choices, it's a matter of top end, so pick your poison the 18G or 20G. In theory when you compare say a TD05 7cm^2 18g to a td05 7cm^2 20g, they should spool the same, with our high school pysics telling us that the 18g version would probably get there a touch quicker due to it's reduced size/mass.

So you pick 18 or 20 based on your WHP goals and you pick TD0X and Xcm^2 based on your spool goals. Talk to a turbo Vendor though as their real world knowledge may assist as theory does not always equate to real world results.

Mind you...............this is all theory. You are building a Frankenstein unit that is impossible to plot like a traditional, purpose built turbo. Your mileage may vary, don't run with scissors, exempt in Hawaii and Alaska, etc.
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Old 01-24-2007, 01:03 PM   #16
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If I had a 2.5L, I'd run a TD05 hot side, "big 16G" compressor, external wastegate, and water+meth injection.

That would make an awesome setup with at least 310whp and GOBS of torque from 3200-5500 on a non-inflated dyno, IMO.
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Old 05-15-2007, 12:28 AM   #17
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Bump! This thread is great I don't kow how I missed it the first time around. I hope it doesn't die. I'm been researching my next turbo for a long time and oversteer has asked the exact questions I've been tyrying to answer through lots of searching.
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Old 05-15-2007, 10:41 AM   #18
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Quote:
Originally Posted by import111 View Post
From what I have been told, the 7cm^2 Mitsu hot side is indeed larger than the VF39's P18 hot side. If I can ever save up enough $, I will be trying a td05h 20g with 7cm^2 hot side with an external wastegate and a reversed intake manifold/FMIC setup.
I've got a similar setup about to go on my STi. Deadbolt TD05-20g 7cm and external WG, but I'm opting for the bigger TMIC and lots of coating/shielding instead of FMIC. I'm also doing the TGV deletes and some other misc stuff, so it will be interesting to see how it all turns out.

Jorge at P&L tuned my regular stage 2 map last year, and I'm having him do this map, too, so I'll post the before/after once it's done (probably not for a month or so).
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Old 05-15-2007, 11:54 AM   #19
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Quote:
Originally Posted by jblaine View Post
If I had a 2.5L, I'd run a TD05 hot side, "big 16G" compressor, external wastegate, and water+meth injection.

That would make an awesome setup with at least 310whp and GOBS of torque from 3200-5500 on a non-inflated dyno, IMO.
I don't mean to be harsh, but that seems like a waste of a 2.5. EWG ?? why spend the $$$ . Yes, you will spool quick, but your top end still won't be all that.

I have a 2.5 w/TD06-18g 8cm2 IWG, I don't have any problems with the spool. In fact, I thought about a jumping to the 20g since I already took the spool penalty with the TD06/8cm part. TGV deletes would negate the minor difference between the 20g/18g part. fmic vs tmic would pose a much greater impact to the spool.
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Old 05-15-2007, 01:42 PM   #20
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Just for point of reference I have used the TD06/18G on WRX's with 2.5 liters and it works extremely well. Full spool in the 3100 range with 310-320 WHP on 93 octane easily achievable. Boost is nice and consistent and doesn't get drop off at the top end like the TD05/18G
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Old 05-15-2007, 03:38 PM   #21
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Great thread! Keep the info coming.
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Old 05-22-2007, 08:38 PM   #22
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How about anybody that can give numbers on either the TD06-18g and the TD05-20g on the 2.5l. But... compairing the whp numbers, and the differences between using meth injection and or tmic and fmic. Because these turbos will produce roughfly the same numbers, how will they differ using different set-ups and which will prove to be better for which purpose it is used for. Is the 20g going to be better for a fmic or will the 18g be better with meth. Answers like these might better help people better decide on which route to go. If any one has one of the following set-ups please tell how it works for you or how it dose not.
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Old 05-22-2007, 10:34 PM   #23
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Old 07-11-2007, 07:39 AM   #24
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Quote:
Originally Posted by Unabomber View Post
Here's my help as I'm in the midst of a highly technical give it hell no kidding watch what you are doing Turbo FAQ article for Subiesport Magazine:

<--fast spool/lower power------slow spool/higher power----->
TD04--------------------TD05----------------------TD06
7cm------------------------------------------------8cm

As to your wheel choices, it's a matter of top end, so pick your poison the 18G or 20G. In theory when you compare say a TD05 7cm^2 18g to a td05 7cm^2 20g, they should spool the same, with our high school pysics telling us that the 18g version would probably get there a touch quicker due to it's reduced size/mass.

So you pick 18 or 20 based on your WHP goals and you pick TD0X and Xcm^2 based on your spool goals. Talk to a turbo Vendor though as their real world knowledge may assist as theory does not always equate to real world results.
So based on this and all other aspects of a turbo being constant what turbine wheel / exhaust housing would spool faster:

a TD06 7 cm^2 or a TD05H 8 cm^2?

Last edited by coolcougar; 07-11-2007 at 07:51 AM.
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Old 07-11-2007, 10:49 AM   #25
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Evoiii 16g Ftw!!!!
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