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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 07-03-2006, 11:41 PM   #1
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Okay, I've considered strongly finding somebody who doesn't want their Greddy kit and just buying all the piping and accessories from them, and then getting a different manifold, downpipe and turbo. It seems like the 15G gets inneficient and is trying too hard after about 200 whp.
I would liiiiike to use a T25, but I am new to the turbo world and don't understand turbo designations/sizing/specs as well as which turbos fit which sized manifolds etc. Is there anyone who can help me out with this or knows of a place that has a list of which ones will bolt up to the same manifold flanges etc.?

Essentially, I like the T25 for how is spools quickly, maxes at ~250 whp (so my goal of 200 whp is in a very efficient range for the turbo) and using a different manifold and DP would avoid the notoriously weak Greddy units. But I don't know what to look for in a wastegate or DP to know if it will work for a T25, and I don't know if all "T25"s are created equal or if all the other 'trim specs' and such factor in - I would probably get the turbo off ebay or some similar source so I'm not sure what to look for to know if its the right one for me

Any help/info greatly appreciated!
-Ryan
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Old 07-04-2006, 12:26 AM   #2
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t25/t28 its a t25 with a bigger intake wheel.spools up quick and can hold the boost longer.
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Old 07-04-2006, 12:54 AM   #3
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The TD04H-15G that comes with the Greddy kit can flow 428cfm (32.5lbs/min. @ ~60% efficiency) vs. the GT2554's ~365cfm (~27.5lbs/min. @ ~65% efficiency). The GT2554/T25 will be tapped out by ~220-240rwhp on a Miata (260-280hp at the crank...best I've seen was ~240rwhp on a Miata), while the TD04H-15G has hit 268rwhp (~315+hp at the crank) here: http://flyinmiata.com/tech/dyno_runs/Danny_G_081701.pdf and at least 245rwhp (280-290hp at the crank) here: https://www.miataturbo.net/forums/showthread.php?t=2814
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Old 07-04-2006, 09:09 PM   #4
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Then why do I hear from some people that the 15G is not a good match for the miata's engine? I know the T25 is supposed to spool faster than the 15G - do people say the 15G is not a good pair for our engine because it takes longer to spool?
-Ryan

Oh, and what is the TD04 designation? Is it something to do with the flanges or family or turbos? Do all TD04-XXX turbos bolt up to the same manifolds/downpipes?

If so, what is the difference between the 15G and the 13C you run bripab007?
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Old 07-04-2006, 11:20 PM   #5
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Yes, the TD04H-15G is, by some people's standards, a bit large for the 1600cc of exhaust gas our Miatas produce. Others, such as the people driving the 245-270rwhp 15G setups might think otherwise; if 245-270rwhp is your goal, you're going to have to use a turbo of approximately that size and spool characteristic. If you goal is 200-240rwhp, then the T25 is probably the "correct" size.

I believe the 15G is Mitsubishi's compressor housing size designation, while the TD04 is the turbine housing designation, so my 13C has a smaller compressor housing. The wheels are also differently-spec'd. All TD04s do not bolt up to the same downpipes or manifolds. Mine has a 3-bolt compression flange for the downpipe, and the turbine-to-manifold flange was a strange, Volvo-specific T3 flange that I machined down to be about like a std. T3 flange.
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Old 07-05-2006, 04:00 AM   #6
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Oh my... confusing.
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Old 07-05-2006, 04:32 AM   #7
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I run the 15G, I like it and dont realy have any lag. Spools fast too. I think i am only making about 180 at the wheels, but then agin im only running a safe 5 pounds right now. Full bost at (2ed-3200rpm, 3rd 3200rpm, 4th-2800,)
Not 100% on all the numbers have had the car tooooo long and havent really been looking.
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Old 07-05-2006, 11:56 AM   #8
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Quote:
Originally Posted by ThePass
Oh my... confusing.
Do you want me to expound upon anything? What do you need help understanding?
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Old 07-05-2006, 10:18 PM   #9
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Well, if I do try to just peice together a turbo setup, the only thing I really am worried about is getting the right turbo with the appropriately fitting wastegate and downpipe. So... when you buy a turbo it comes with both the compressor and turbine side of the turbo. But, those two parts are seperately designated because...? Can they be taken apart and fitted to different parts, for example your 13C compressor which is attached the TD04 turbine - did it come that way or did you put them together?
And how do I know what manifold/dp will fit a TD04 15G turbo? Actually, I guess the 15G compressor side doesn't matter for that fitment - its tjust the TD04... but you are saying that not all TD04's use the same flanges... so a manifold or dp that is "for a td04" may not fit??
Are there any good places that sell them? I shy away from Greddy/s peices because their manifold cracks and their dp is a small diameter and has a tendency to break bolts....

Oh and last, different company's manifolds have different turbo placements... yes or no? Because if so, I guess I have to get a manifold and dp from the same company because only that company will make a downpipe that will match up to the location that theie wastegate will make the turbo sit at... yes?
-Ryan
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Old 07-05-2006, 10:23 PM   #10
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Quote:
Originally Posted by TurboMiatKid
I run the 15G, I like it and dont realy have any lag. Spools fast too. I think i am only making about 180 at the wheels, but then agin im only running a safe 5 pounds right now. Full bost at (2ed-3200rpm, 3rd 3200rpm, 4th-2800,)
Not 100% on all the numbers have had the car tooooo long and havent really been looking.
180 whp w/ only 5psi? What else is done to the car/what have you upgraded on the tubo setup? That seems very very high. I've seen some people with 8 psi only dyno 180 whp with the Greddy kit... My goal is 200 whp with 10 psi...
-Ryan
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Old 07-05-2006, 11:30 PM   #11
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Yes, every vendor sells a different manifold, so to piece together a kit, you're going to have to at least buy the manifold and downpipe from the same vendor, and possibly the turbo as well, unless theirs is designed to work with a fairly standard turbo with fairly standard flanges.

Yes, the compressor and turbine are two separate parts that are each attached to either side of the center section/cartridge. The center section is what the compressor and turbine wheels rotate in/are attached to. Yes, a lot of times it's possible to swap wheels and housings around; it's done quite often, but not always with great results. A car company or turbo manufacturer specs out a turbo with certain things in mind, so many times it's best to go with what they've designed to begin with. Yes, in theory, I could fit a 15G compressor to my TD04 turbine housing and center cartridge, but my compressor wheel might be too small to work effectively in that compressor housing; it may introduce new problems. My TD04-13C came off of an early 90s Volvo 940 Turbo.

Yes, different Mitsubishi turbos have different flanges, and different TD04 housings have different inlet and outlet flanges. Volvo may decide they want a particular flange for the 940 Turbo that uses a TD04 housing, while Mitsubishi used a more generic flange on their 3000GT VR-4 (which had two, tiny TD04-09B turbos, but it had 1.5L of displacement pushing each one...I've only got 1.6L of displacement pushing the next larger size compressor housing in that turbo family). The Volvo turbine inlet//manifold flange also is a T3 size and bolt pattern, while, I think, the 15G in the Greddy kit uses a T2 size and bolt pattern.

Is that enough to chew on for a little while?
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Old 07-05-2006, 11:44 PM   #12
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Oh boy lol thanksf or all the info...
Seems like since this is my first turbo setup and I am learning all along the way, I had better just bite the bullet and get the Greddy setup even though I am wary of their manifold and downpipe... I don't want to get in over my head.

I also thought that by peicing a setup together I may save a few $$ compared to getting the Greddy kit and adding the IC and AFPR etc. because I could just get the IC piping straight away and also an AFPR instead of buying the Greddy kit, and tossing the rrFPR and crossover tube when I added them later. Didn't make sense to pay for things I will swap out anyways but... for simplicity's sake I think maybe the kit is the best thing for me.
-Ryan
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Old 07-06-2006, 12:19 AM   #13
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I would think long and hard about going with a BEGi manifold (http://bellengineering.net/Pages/pro...tmanifold.html) and downpipe (http://bellengineering.net/Pages/pro...peupgrade.html) to start a kit. I mean, these pieces are sooooooo much nicer than the Greddy stuff.
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Old 07-06-2006, 04:18 AM   #14
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I agree those peices look beautiful, but that would mean I have to go find a T25 - and from what I'm seeing there are just too many different variations and things for a beginner to this scene to be able to know I'm picking all the right parts. To be honest, if I could get the manifold/dp from begi and find a proper t25 on ebay or something, the biggest problem for me would be to know about all the little things I would need to get that normally come in the kit like oil lines/fittings/washers that all have to be certain sizes and such...
-Ryan
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Old 07-06-2006, 08:16 AM   #15
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Don't worry about the little things; we can help you with those, too. The bolt/stud sizes are pretty easy because you can just bring the turbo and/or manifold to the hardware store and match them up with what you need.
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Old 07-06-2006, 11:15 PM   #16
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Let's assume I bought the BEGi manifold and DP - how much does a T25 run on average, and is BEGi's stuff made for the Nissan, eclipse, or a different version of the T25?

The appeal of the Greddy kit is that I can spend 1600 and get a starter kit + bipes and boost and oil temp gauges, get it on the car, and then over time I can work towards my goals - adding intercooler, AFPR, boost controller, bov, wideband, injectors, oil cooler...

If I try to source a kit together myself I don't start with alot of the things the Greddy kti comes with like the rising rate fpr, the crossover tube, the 6psi max wastegate.... so I have to purchase a bunch of the things I wanted to add on later initially just to get the kit on the car - I have to get the Intercooler and associated pipes because I'll have no tubing to run for now, I'll have to get the BEGi AFPR right off the bat, as well as a manual boost controller, plus all those little things like oil lines, fittings, silcone hose connectors, clamps, etc.

So I priced it out:
If I go with the Greddy kit it will be $1600 for the kit/ Bipes / boost+oil temp gauges. And the end result for 10 psi will cost me $3100. And I can spread the $1500 difference over the course of a year as I slowly make money and put it into the car...
If I go with a peiced together kit, its going to cost $1475 + the cost of a T25 and all of the fuel & oil lines, fittings, hose connectors, and clamps... so how much should a T25 and all the misc. parts cost? But then its only another $850 after that to reach my same goal for parts because I've already bought alot of the parts initally that I would have had to swap out for on the Greddy kit... and then I've got a far better manifold and dp...

-Ryan
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Old 07-06-2006, 11:18 PM   #17
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I would say go greddy. Itll be alot cheaper. PS you can get greddys 1200 shipped, and with gauges your talking another 250, get a used bipes or new I bet you can do it for around 2gs if your careful.

MBCs can be had for 15 dollars on ebay or make one (ebay for sure)
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Old 07-06-2006, 11:52 PM   #18
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Quote:
Originally Posted by Loki047
I would say go greddy. Itll be alot cheaper. PS you can get greddys 1200 shipped, and with gauges your talking another 250, get a used bipes or new I bet you can do it for around 2gs if your careful.

MBCs can be had for 15 dollars on ebay or make one (ebay for sure)
Thanks for the input. For gauges I plan to do the oil temp and boost gauges first - only ~$55 each, and then a wideband A/F wich will be $280 so really end result is $400 for gauges - but its been chanted down the streets that its worth it to have the wideband, so I'm willing to get it.
And I'm not sure about making a MBC - I prefer paying a bit more and knowing someone made it who knows it will work right, but who knows maybe when the time comes to bump it above 6psi I will go that route.

Yes, it'll just barely hit $2k for the Greddy kit + bipes + boost & oil temp gauges + intercooler & piping + porsche 944 bypass valve. But thats only the first stage and will be 6 psi. Then MBC / injectors / wideband / AFPR are added and the boost will go up to 8 psi and that will put me at ~$2800.
After that I'd like to see 10 psi but before I do I'll add an oil cooler / oil thermostat kit and perhaps a fuel pump depending on how a current discussion about the fuel needs for 10psi goes on miata.net...

-Ryan
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Old 07-07-2006, 12:09 AM   #19
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Look for things used. I got Injectors, MBC, AFPR, fule pump for 400 and wide band is 250 on ebay. http://stores.ebay.com/Kuruma-Motoring
check that guy. I have a bypass valve bosch type off a supra ill sell ya. Its possible just take your time and talk to everyone
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Old 07-10-2006, 04:18 PM   #20
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I agree- your prices are higher than what you need to pay. Do some shopping. I got a used turbonetics t3/t4 with less than 1k miles on it for $350. That's about a 40% discount over new. Not everything has to be a bolt-in for a Miata either. I picked up some used rx7 550cc injectors for $75 and used some NAPA pigtails at $12 to wire them in to the stock harness. I've got a supra fuel pump now, and used a high pressure mustang pump on my previous Miata. Research can save some and asking questions can save you some dough. - rob
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