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Old 07-16-2006, 04:10 AM   #1
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Default T28 or T25 and what do I look for in a turbo?

So seriously considering not getting a Greddy kit and doing a DIY setup... if I do that allows me to pick the turbo that I really want... obviously I'd like minimal lag so the T25 looks nice, but I'd rather get a slightly larger turbo that can flow a bit more per psi so I can get a bit more power per psi instead of having to really up the pressure to get the power... I think the T28 would be the best choice... any input on how much of a difference the two have in spool up vs. power output?

And when shopping on eBay for a T28, and for downpipes and manifolds, will any manifold/downpipe made for a T28 work for a T25 and vice versa?
What should I look for when shopping for a T28? I hear alot about trim numbers and some turbos with the same designation but different trims being very different... so what should I look for? And I see alot of the Nissan T28s off of things like the S14 - if I picked up a used one of these would it work well or would it be inferior to some other type of T28?

ANY info greatly appreciated!
-Ryan
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Old 07-16-2006, 08:17 AM   #2
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T28's are commonly found on Nissans. There are some older ceramic wheel style ones, those aren't really know for longevity.

Finding a T25 may be easier... I used a T25 off a Nissan 300zx. These can usually be had very cheap(~150.00 still in good shape) Both Saab and Volvo used T25(or slight mitsi variants) over the years. These can be picked up cheap as well.

The hardest part of using the nissan I chose was the exhaust flanges(some weird 4 bolt). They are all custom made. Do you have a plasma cutter, or access to one?
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Old 07-16-2006, 01:53 PM   #3
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why not go mitsu and use the megan racing parts with a 16g or other mitsu flanged turbo?
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Old 07-16-2006, 03:19 PM   #4
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The best turbo for stock internals, driveability, power etc, is GT2560R (GT28R)

P.S. For 1,6 lt
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Old 07-16-2006, 03:53 PM   #5
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This is a budget turob setup so even though the 'best' turbo for the 1.6 is the GT2560R I can't afford it - I need to find a good used turbo for cheap that will work well with my car.

magnamx-5: I haven't considered the 16G because I seem to hear that its just a tad too large for our engines... yes I want something capable of a bit more power so I can get more power for less psi, but I don't want to have to wait for boost till wayyy late in the rpms.... would a 16G be a comparable turbo to something like a T28?

Jefe - the reason I am considering a T28 over a T25 is because when I talked to the guys at Flying Miata they said a T25 would max at ~240 whp whereas the T28 could get close to 300... and I really want something that can get me to ~215 whp without having to work super hard and it seems that the T25 will have to spin alot more boost to get that power than a T28 - and on stock engine internals I don't want to run high boost.

I found this on ebay:
http://cgi.ebay.com/ebaymotors/Miata...QQcmdZViewItem
Its a generic stainless steel DP and manifold combo. Obviously the price is beautiful... are these akin to the Megan racing ones or are the Megan ones different? This combo says its for a T25 / 16G - does that make sense?? Do those turbos both use the same mounting flanges etc.??

P.S. no I don't have a plasma cutter. why?

-Ryan
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Old 07-16-2006, 04:41 PM   #6
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goto the garrett site. the t28 lags more at the bottom. i'm using a gt25r (gt2554r) if your goal is 215rwhp, the gt25 is a bit better, imho. you can get supercharger pull without the lag of the 28.

the 16g and t2 flanges are imilar, that one may have oversized holes to accommodate both.
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Old 07-16-2006, 05:29 PM   #7
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Quote:
Originally Posted by ThePass
I found this on ebay:
http://cgi.ebay.com/ebaymotors/Miata...QQcmdZViewItem
Its a generic stainless steel DP and manifold combo. Obviously the price is beautiful... are these akin to the Megan racing ones or are the Megan ones different? This combo says its for a T25 / 16G - does that make sense?? Do those turbos both use the same mounting flanges etc.??

-Ryan
yes if you understand one thing. That manifold is for a mitsu styled turbo, and in the mitsu world, the stock 2gen turbo came with a t-25 that had a mitsu exhaust hosuing. That is why it has T25/16G it setup for only the mitsu turbos, you can not run any other turbo with out doing custom work.

Do some searching, there are some people running around this boarding using that manifold and you can read thier reviews. Most people well tell you to avoid them, unless you can weld the cracks when they form and you have a mitsu turbo laying around, or can get one for less then 75 dollars. Other wise get a normally styled T-25 and then a HKS manifold or another. That been said I plan to use that manifold/Dp in the future, but I already have a t-25 and 14B from when I owned a DSM.

Hope that helps
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Old 07-16-2006, 05:58 PM   #8
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that is the megan racing manifold set my small 16g makes 2 psi by 2k rpm if i lug into it in fifth it spools pretty quick and out flows the big 16g until you hit 16psi at 8 psi i got 176 whp on a mustang chassis dyno with a fpr, WI and stock 1.6 fuel pump, injectors. as for the manifold quality the dp is abit off and will probably need ot be corrected but no craking to date after about 7000 milesof boost now at 10psi and loving it.
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Old 07-17-2006, 01:30 AM   #9
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Aren't the HKS manifolds really pricey / wheres the best place to get them? And I'm assuming that you would then need both the HKS manifold and Downpipe yea?
Oh, and by 'normally styled' T25 what do you mean - would a Nissan T25 or T28 fit that description?
-Ryan

Last edited by ThePass; 07-17-2006 at 01:43 AM.
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Old 07-17-2006, 02:15 AM   #10
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If you took a T28 and T25 turbo... and put them on identical cars at say... 8 psi, the T25 would spool faster but make less hp and the T28 would spool slower and make more power correct? So how much of a power difference are we talking between them? I don't want a super laggy turbo but I want something that will give me a very solid amount of power at 10 psi.

I want to pick the right turbo... I want to be able to get good hp levels without having to up the boost too much. I'm afraid that the T25 gets inneficient around 200 hp - you have to crank the boost up more and more to get a just bit more hp past 200 whp... if thats not so, set me straight and I will go with a T25! Yes, my goal is 215 whp... but if I do want to go past that down the road I dont want to be running a T25 if its going to be practically maxed out at that point.
-Ryan
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