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Discussion Starter · #1 ·
I've posted about this before and gotten no volunteered info except my own. If anyone wants to add to my datapoints, please do!

Background: Turbo compressors (the cold side) all have a compressor map which makes it relatively easy to see how a compressor will work with our 2.7L V-6.

Turbo turbines (the hot side) on the other hand are a bit less scientific and kinda have to be tried out. Ignoring some of the fancy design variables, I want to discuss A/R as it is most referred to as the critical measurement on the turbine side.

A/R is a complicated ratio calculation of the large part of the turbine housing vs the small part of the turbine housing. Suffice it to say that a higher A/R will create less exhaust back pressure but will spool up slower. Always life is trade-offs!

Understand that I'm trying to simplify this way beyond reasonable, just for this discussion.

My very first turbo system had a 0.63 A/R turbine with a 0.50 A/R compressor. This turbo spools up REAL fast, but can't hold over 6.5psi (at the intake) thru the entire rpm range. The compressor is just too small.

The turbos that I sold in the 'Duffers Six' have the same 0.63 A/R turbine with a larger 0.57 A/R compressor. Tho I have not run this turbo myself, feedback says it will hold 10psi and still has that quick spool.

The 0.63 A/R turbine is readily available in the Ebay turbos. Then they jump up to around 1.0 A/R so that's what I am testing now. And it's TOO BIG! I've been spending all week sorting out how my EBC works (see other thread) and finally got it working but still was not getting big boost numbers that I expected from this turbo.

So this morning I ran it straight. No wastegate at all. Totally turbo. Here's what I see. (remember I have an automatic trans) thru 1st gear the boost gauge will start to climb to about 3psi. At the shift it will jump up a bit and thru 2nd gear it will hold about 6psi. It will jump again at the shift to 9psi and it will hold into 3rd gear where I'm now going like 80mph and have to get out of it.

The 1.0 A/R turbine takes an automatic, with foot on floor, into 3rd gear to reach 9psi. It may climb higher, but very slowly.

I wish I had some 'in between' data for turbine A/Rs in the 0.70s or 0.80s. There are no cheapo Ebay turbos that I see in this range.

Might have to actually buy a name brand turbo!
 

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You can get a .83 kidna cheap

And its quite in between of both of the situations you mentioned. Its not instant boost, but its not starting boost at 6k either.
 

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Welp I didnt turbo the tib but I have similiar displacement now. I just dont know how much the heads are gonna hold the tib back. My Ideal turbo is the GT3076 from Garrett. It has a 60mm turbine wheel with an 84 trim and 76.2mm, 56 trim compressor wheel. I will hit full boost on this at ~3800rpm and it flows enough to hit over 500hp at the crank. But I will be running at or over 20psi so im not sure how it would work in a low boost situation. I always wanted to see the discopotato on a tib although its a little small i think for a 2.7l motor, it would be a good powerlevel for a stock motor. Youd be maxing it out at like ~290whp. Even the other brand turbos im looking at (namely blouch) they use the garrett dual ball bearing center.
 

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Discussion Starter · #4 ·
Welp I didnt turbo the tib but I have similiar displacement now. I just dont know how much the heads are gonna hold the tib back. My Ideal turbo is the GT3076 from Garrett. It has a 60mm turbine wheel with an 84 trim and 76.2mm, 56 trim compressor wheel. I will hit full boost on this at ~3800rpm and it flows enough to hit over 500hp at the crank. But I will be running at or over 20psi so im not sure how it would work in a low boost situation. I always wanted to see the discopotato on a tib although its a little small i think for a 2.7l motor, it would be a good powerlevel for a stock motor. Youd be maxing it out at like ~290whp. Even the other brand turbos im looking at (namely blouch) they use the garrett dual ball bearing center.
The GT3076 has a nice compressor map, but there again you have the choice of Turbine A/Rs. You can get the GT3076 with a 0.63, 0.82 or 1.06 A/R and the only way to know which one works best on the Tib is to try each! (or get some brainstorming together creating an educated guess)
 

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Discussion Starter · #5 ·
You can get a .83 kidna cheap

And its quite in between of both of the situations you mentioned. Its not instant boost, but its not starting boost at 6k either.
I'll do some more searching. I'd like to try a 0.83 turbine if I can find one!

The auto tranny can get away with a higher turbine A/R. I don't mind the first gear lag since there's no traction down there anyway. Just need boost by 2nd gear!
 

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im not intirely convinced that im giving up a VGT turbo,
here is a link i was reading about a man that put a VGT holset on a DSM 1gen eclipse! if his posts are right than hes running like 30 pis and something like 400 hp, i deal VGT turbos all the time in out new cat accert stuff these equipment compared to the latter stuff if night and day and thats all due to the accert technology and the miller cycle in the intake valves, and most importantly dual turbos that run VGT in them, the VGT in this equipment is controlled by ECU so its maximized for tier 3 emmisons, now what im saying is that having turbo laga and being able to change the fin possition is turely amazing and proves it self in these appplications, now my lack of knowlde on other system like the smaller ISB cummins and the newer powerstroke turbo is my down fall, the stone age VGT was controlled by a vacum actuated solinoid and i wonder if we can addapt this technology to our use

http://www.dsmtuners.com/forums/turbo-system-tech/323774-holset-he351-vgt-goin-my-car.html
http://www.fordtechservice.dealerconnection.com/vdirs/subsites/diag/6lvgtguide.pdf

im a repair by replace mechanic and my skills at addapting this to our use ismuch like giving a 10 year old hammer and telling him not to hurt himself! but for your consideration i give u the reseach that ive got complted and the 2 most usefull links that i found!

hope u genius rockstars can do more with it than i can!
 

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Discussion Starter · #9 ·
I know the .82 is popular because the .63 falls off a bit up top. But you are right, nothing is easy. I know what I do about the garrett turbos because of other peoples experiences, but like you said you dont have that in this community.
I found and bought another cheapo Egay turbo! You guys KNOW how much I love beating on these cheapo turbos!!! It's on its way. It has a 0.70 A/R compressor and a 0.82 A/R turbine. It should bolt right in place of my current one. I did HOURS of research trying to find a comparable compressor map for the turbo specs that were listed on the ad and found a couple very close.

It's about half-way between a T04E-46 and a T04E-50. Basically a knock-off of the HKS GT3037. Problem is HKS never posts their compressor maps. Both of the T04E's maps look good tho.

Here's another rant about Evay turbo ads. These idjits don't know what turbo they are selling! So don't believe the title, which in this case identified this turbo as a T-70. It's no where near that big!!! Once I sat down with the listed specs, which at least this ad posted, I was able to figure out what it actually was. Ads will often say" T3/T4, T04B, GT35....." on the same turbo. Those turbos are completely different beasts.

If the ad gives you no specific specs, you have no idea what you are getting cuz they have no idea what they are selling! :3_lijstje

I see this alot on Craigs too. Kids selling turbos by size and some huge horsepower number. "450hp turbo for sale. Huge!" and a pic of the turbo sitting next to a pack if cigs!
 

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IMO, the perfect turbo for our cars would be one that allows a bit of lag in at low rpms.

a gt35r with a a/r a ranging around .65-.75. I wouldnt go with a bigger compressor than .70 though.

Since your going for a low boost setup (low because anything under 20psi is low in this world) one cant really say how efficient turbos made for 30psi+ will work. Imo, if you going for less then 10psi, stick with a .6x a/r. I've seen people call gt35 turbos trash because they dont boost higher than 12psi.

Of course this all changes if your using a multy-stage ebc.
 

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Discussion Starter · #12 ·
Yeah! My newest turbo arrived. I LOVE Ebay turbos! Don't like your turbo? Spend a couple hundred bucks and buy another one! Hopefully installed Monday. It's a 0.70A/R compressor and a 0.82 A.R turbine. Interestingly, it's a split exhaust inlet, but not a T-4/T-60 sized flange like the last one. It's a split T-3 flange, so I have to build a new inlet. Oh well.

ot btw: got my 15mm/25mm spacers installed and my rear fender lips rolled. Huge improvement to the stockers since the wifee won't let me spend on new wheels.
 

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Discussion Starter · #16 ·
Yeah! My newest turbo arrived. I LOVE Ebay turbos! Don't like your turbo? Spend a couple hundred bucks and buy another one! Hopefully installed Monday. It's a 0.70A/R compressor and a 0.82 A.R turbine. Interestingly, it's a split exhaust inlet, but not a T-4/T-60 sized flange like the last one. It's a split T-3 flange, so I have to build a new inlet. Oh well.

ot btw: got my 15mm/25mm spacers installed and my rear fender lips rolled. Huge improvement to the stockers since the wifee won't let me spend on new wheels.
So the latest turbo is installed. That took WAY longer than it should have. All my fault.

First didnt notice that although the new turbo is divided turbine and the old one is also.... new one is T3 and old one is T4. So gotta weld up another flange.

then, there are apparently be two different '2.5" 4-bolt' outlet patterns. Modified that flange too.

then also didn't see that the compressor outlet is 2.5". Luckily I have extra couplers.

and lastly, my adaptable air filter does not go up to 4"! So I gotta fab one.

Made a test boost. By redline, I had hit 8psi and I got out of it. Needs some time to reset the fuel trims and then I'll make some tuning runs, but she spools up nicely.
 

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Discussion Starter · #18 ·
Learned a bit more today. I've had to turn down the Profec quite a bit to get this boost under control. I want to start at 5psi again. Get a better handle on the tuning and then bump it up.

The turbo spools up nicely. Not nearly as fast as the .67 A/R turbine, but fully boosted by the shift to 2nd gear. That's what I want. By increasing the gain on the Profec, I was able to lower the shift surge to +1psi. So I hit 5.5psi by 5000rpms and then it surges to 6.5 at the 2nd gear shift and settles back down to 5.5psi thru 2nd. The open-dumped wastegate does get kinda loud at the shift surge point, where the Profec opens the w.g. hard to control the surge.

Also tapped my boost gauge straight to the turbo, (the Profec is to the intake) so I could measure the pressure drop across the new FMIC...... and it's only 0.5psi! The same side unit had a 1.5psi drop. I'm sure the cross-flow is not cooling as well as that huge same-side, but I like it alot and I think it's gonna work well with this newly designed system!
 

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What WG you have? how the vacuum hose are connected? how is the WG botled?

BTW
that "T70" you have is a big MOFO :D thats what the fastest only turbo v6 have right now
IMO for an automatic a .82 turbine is a bit big "laggy" the perfect combo is a 57trim/.63turbine
for a Tib auto and for anyone who want 280whp or so with only 6~8psi.
 

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Discussion Starter · #20 ·
What WG you have? how the vacuum hose are connected? how is the WG botled?

BTW
that "T70" you have is a big MOFO :D thats what the fastest only turbo v6 have right now
IMO for an automatic a .82 turbine is a bit big "laggy" the perfect combo is a 57trim/.63turbine
for a Tib auto and for anyone who want 280whp or so with only 6~8psi.
My wastegate is an ebhay knock-off, plumbed into the 'Y', dumping to atmoshpere and vacuum hosed as per Profec instructions.

I've dyno'd the .50/.63 and the .57/.63 is what comes in my kits. I just wanted to try something bigger. No so big that the lag is like running a jet boat, but enough lag so that first gear does not just immediately go up in smoke!

and with the auto, I don't have that drop between gears. The boost just stays up there once it gets there.

I also wanted the ability to boost double-digits.10, 11, 12 or more. Still trying to pop my stock engine, don't ya know!
 
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