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By gt4tified
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#10405
For the folks who have boosted their G13b using oem rods with either G15, G16 or Honda D-series pistons, do you have any idea how much hp the stock rods can take, or how much boost? Let’s say 8.5:1 CR on a standard T3 or T25 turbo.
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By GT4LIFE
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#10407
I don’t want to find the limit, but they are taking everything I’m throwing at it with Vitara Honda pistons (It is more likely a 8:1 compression ratio).

You can still get the aftermarket forged rods, but unless I was shooting for high 200 hp or 300+hp I decided not to.

There are other turbos out there besides Garrett with T25 inlet flanges, but the following should help:

There are three models of T25 Turbos: the GT2554R-471171-3, the GT2560R-466541-1 and the GT2560R-466541-4.

Turbine Dimensions
The turbine for all models of the T25 has a 41.7 mm exducer and a 53 mm inducer with a 62 trim and an A/R of 0.64. This is roughly the same same turbine size dimension of the IHI RHB5200 I’m running. The GT2554R-471171-3 compressor has an inducer of 42 mm and an exducer of 54.3 mm. This also matches close to the RHB5200. The other two turbos have slightly larger compressors, but I doubt they will match as well on a compressor map with a 1.3 G13B.

Using the above T25 even with everything else setup up perfect for intake and exhaust side I doubt you would damage the rod unless you had an ignition or fuel problem. Boost is a term that doesn’t mean much since it doesn’t correlate the same with output from turbo to turbo, and setup to setup. If you are talking about a specific turbo boost or pressure ratio will give you some perspective. At best with the T25 with a setup similar to mine you would make about 210 hp at 15 psi. I haven’t taken a look at the compressor map but I doubt it will make much more over 15 psi.

As I currently look through the line up of turbos there are more contenders using a T25 flange then a T3. Most of the new T3 don’t match are engines well .

T3 inlet flange turbos have a huge range where anything over a T3-50 the hp output can be incredibly high where even with everything set right for fuel and ignition you can start exceeding the strength of your parts. Anything over a T3-50 is probably not going to match well with our engines either.
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By gt4tified
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#10408
Thanks brother. I appreciate the in-depth response. This is what I love about site forums over social media - it allows for fruitful, educated discussion. I am hoping we can rebuild the popularity of this site, as there seems to be quite an international following for our cars.

So given your response, what’s your take on these Chinese turbos that have flooded eBay? For a moderate setup on about 1bar boost? I’m looking to build a budget turbo engine using an old 1st generation Link EMS. Not. Looking to go wasted spark so I’m keeping the distributor. May just upgrade the coil to an MSD Blaster.
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By GT4LIFE
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#10411
I would narrow your search first with these questions:
  1. Are you planning on running an internal or external wastegate? This will change your selection choice right there. I’m trying to buy a ceramic ballbearing Turbonetics T3 50 but I need a 4 bolt hotside exit that doesn’t use the internal wastegate housing. I’m definitely going external wastegate to take advantage of my ram horn exhaust manifold with the T3 merge collector with wastegate port. This will give me a lot more control over the turbo. I have to call Jegs to see if they can order that specific one since Turbonetics will not return emails and will not answer the phone. If there was a T25 merge collector that was as nicely built as the cast stainless Treadstoneperformance one I would have bought that to give me more options.

  2. Are you planning on running oil and water cooled? I definitely am and would recommend it.

There isn’t anything wrong with making a cheap journal bearing turbo. The component parts of a Garrett journal turbo are not rocket science. These designs are over forty years old. The parts that get expensive are the turbine/wheel and the bearing systems. The CHRA (center housing rotating assembly) should be fine. Float bearings in journal bearings turbos are literally brass rings with holes in the them. The rear and front seals are prone to leak some. My rear seal on the brand new CHRA I bought leaks (more like a fine misting that does show on my dip stick). It is not effecting my performance, but it is making a mess and I also think it kills my wideband sensors super quick.
  1. What turbine size (inducer/ exducer) with what A/R do you plan on running? I wouldn’t buy an Ebay turbo that doesn’t specifically list these dimensions. Since there is no specific maps for these turbos your matching them with compressor maps that are similar vs. turbine size including A/R. I wouldn’t exceed much past a 60 mm turbine inducer, and wouldn’t recommend anything larger than a .80 A/R. I’m looking at the .63 A/R housing on the Turbonetics T3-50.

  2. What compressor size are you going to run? The T3/T4 hybrids are all too large. I’m looking as an example at a GT3076 T3 flange turbo on Ebay (link below). The turbine size will work nicely but the compressor is too large. The compressor will change the flow characteristic enough where it will be too far to the right to match are relatively small engines.

  3. What size compressor inlet? A 4″ inlet is going to be a nightmare to fit and will most likely be paired with a compressor that doesn’t match our engines. I wouldn’t exceed 60 mm compressor exducer.

https://www.ebay.com/itm/283773058394?h ... SwCYJdf0Ad
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#10443
On my turbo gti I was using a td04-13T at 16-18psi. Stock pistons, gasket everything.
It made around 205hp. It was a rocket. I did use water / meth injection (AEM).

Was also using 3000gt vr4 injectors and an old apexi super afc and wideband to keep everything in check.

The stock conrod can take a lot. They’re forged.
Walt liked this
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