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KA24DET
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Discussion Starter #21
bridrive55 said:
MAF sensor choice usually goes with management choice. SAFC-II likes the Nissan MAFS. A GTR MAF will handle huge ammounts of airflow (>60lb·min^-1), and the Z32 MAF fits nicely on 3" piping while still being able to process lots of airflow.
To clarify notation, lb·min^-1 reads "pounds per minute."
 

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Metal > Rap
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What about downpipe selection? like using a SR downpipe (performance or stock) for a stock T25/T28, would it even fit up to the catalyst converter?

Maybe I should have asked this on KA-T.org...
 

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KA24DET
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Discussion Starter #23
Nismo14-180 said:
What about downpipe selection? like using a SR downpipe (performance or stock) for a stock T25/T28, would it even fit up to the catalyst converter?

Maybe I should have asked this on KA-T.org...
The stock SR downpipe works on Nissan T2s. It's easiest to get high flow stuff from step one, however. Custom downpipes are manufactured that go past just the "elbow" and bolt up to factory S13 or S14 exhaust loci. EBay it.
 

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KA24DET
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Discussion Starter #24
PICTARS!

Hey guys,
I figured all this talk deserved at least a little pic-action. So last summer I spent all my time and money on my project, but I quickly ran dry, and I was going from paycheck to paycheck, putting every penny in my car. I didn't get anywhere near where I wanted to get, and I didn't work out all the kinks, but here's where I was at:

VLSD swap complete: 1995 Infiniti J30
Race clutch
3" dummy exhaust, welded by buddy... Soon to be redone professionally
T04E
Tial 38mm WG
3" FMIC piping
Type S BOV
Big FMIC (never measured it)
550cc galley injectors
Z32 fuel pump
SAFC-II
Q45 MAF (actually an RB26DETT)
Lots of etc.

So it's not anywhere near done, but here's how it looked when we fired it up to run SAFC-II numbers:


From the front: a modified S13A front end that I had laying around. I know it looks stupid, I just wanted to show how sneaky the FMIC is:


This is the engine when I was redoing the spark system, no exhaust or FMIC piping attached:


So it's nothing special, but when it's done it should be nice. I don't aim for more than 325whp, because it's scary. There's a 2" spring drop as well, and shaved everything. Stock rims and such. I plan to paint it this summer, and get a real exhaust. We did actually port the WG into the exhaust to make it nice and quiet, because I like the whooooosh noise. I ran it at 15psi for a little while, but 7-10 are what it's usually at.
The main point of this project was the engine swap. The turbo kit just kind of fell into place. I really just wanted to wire in an S14 motor because my KA24E spun a bearing.
 

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KA24DET
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1,000 Posts
Discussion Starter #25
Looked up the MAF codes and it is actually from a VH45, not a GTR at all. Stupid importers don't really know where their parts come from. Anyways, just wanted to set that straight.
 

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KA24DET
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1,000 Posts
Discussion Starter #26
DANGER: KA leanout!

Hey guys,
Considerable evidence points to the conclusion that the stock KA24DE OBDI (and KA24E) oxygens sensor band is exceeded by the fuel/air ratios generated when a turbocharger generates atmospheric pressure (manifold neutral pressure, reads 0psi on a vacuum gauge). This preboost spool occurs during regular driving every time the throttle plate is not fully open and manifold (post throttle body) pressure is between 4"Hg and 3-4psi boost. The factory ECU map cannot compensate for the increased air, and unilinear A/F curve adjustments will not compensate for this! Preboost leanout will hurt your KA, so I strongly advise all turbocharged KA's to take extra care in enriching the fuel/air mixture in that pressure range. I recommend usining wideband oxygen sensing and an earlier fuel pressure onset if possible.

The OBD-II oxygen sensors have a wider band (wider voltage range), and this might compensate for preboost leanout. Once again, this is only a consideration on turbocharged vehicles.
 

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KA24DET
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Discussion Starter #27
Oil restriction

Oil starvation and bearing oil seal hyperpressurization are two leading causes of premature turbo failure, when douchebaggery and idiocy are not considered causes of failure. Ensuring the right pressure for your turbo by variable resistance would be the most reliable method of controlling bearing lubrication, but it would be difficult to monitor the pressure adequately right before the oil inlet on the turbo. I've kicked around the idea of a rising-rate resistor linked to a vacuum line (boost line) that would open a valve under boost and permit more oil flow to the turbocharger, but my first design using a modified fuel-pressure regulator failed. The best way remains unilinear resistance of a large aftermarket oil line.
This unilinear (constant, as opposed to variable) resistance is usually achieved by placing a NOS jet in the oil feed line right before the inlet to the turbo. Other down-and-dirty methods include the tapered head of a BIC ball-point pen and the actual piece that I use, which is a selectively cut plastic tip from a micropipet, a device used by molecular biologists (such as myself) to accurately aspirate and deliver small quanitities of liquids. This is a polystyrene cone that I cut at two sections to create a tubule that supplies the peripheral resistance needed to save the turbo bearing seal from hyperpressurization. I recommend the NOS jet route. Do NOT run a turbocharger (especially a T2) without oil resistance of some sort.
Oil starvation can be prevented by monitoring oil lines carefully. If an oil line becomes kinked, the turbo seal will dry out and the bearing will blow. This destroys the turbocharger. Too many good people have sold their cars after the frustration of blowing multiple snails.
 
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