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-   -   HOW TO BUILD A KA-T D21 or Frontier! (

Motorhead 02-27-2013 02:05 AM

HOW TO BUILD A KA-T D21 or Frontier!
This is a guide to building a SOHC hardbody Turbo.

Most of this info also helps if you have a 4 cyl frontier too.This info was gathered by myself and from other members of infamous Nissan and directly from this will hopefully assist you all and future members. With a little bit of ingenuity and fabrication skill these little trucks can become powerful street machines, around 350 wheel hp on the stock bottom end is very common and not unheard of in the s chassis world, and our trucks have been blessed with the same motor! What small sport compact can take that kind of strain stock? Not too many! Also, look at how many members here used to have or still have s-chassis cars. These trucks are cheaper to buy initially and easier to find without being beat to crap from “drifting” because they aren’t super popular like the s chassis YET.

if you have a show truck, its awesome to surprise people with the turbo and it looks awesome, especially if you get a polished compressor housing, or some elbow grease and and polishing...

Anyway, enough rambling, heres some info from the ka-t community.
Together we will go through typical setups from mild to extreme to reach the power goals you desire.
If you are using your truck’s existing motor, regardless of the miles or its condition, I would do a simple compression test to the cylinders to make sure the motor is in good shape. These trucks and their motors are tough, so mileage is not a huge concern here, the condition of the motor (lack of oil leaks, good compression) is what matters in my opinion. If you are using a freshly rebuilt motor, that’s even better. Just follow the proper break in procedure.
If you are using a 240sx sohc or dohc ka24 motor, this has been installed in our trucks before, and has been turboed in our trucks before. It is possible. There are some sticky threads about this already. Oil pan modifications and a different dipstick location, cylinder head differences, etc, is about it.
There are several modifications you can do to your truck before you actually bolt the turbo to it and start boosting. If the truck is your daily driver (which I would not suggest, at least have something else to drive in the meantime imo) you can install the 240sx intake and maf (recommended, easier to connect charge pipes, less restrictive), bigger fuel pump, the wideband 02 sensor, the oil drainback hole (you can install it and put in a plug temporarily) and most of the intercooler piping. Also, if you want to rebuild your motor you have to think about running a stronger bottom end with the correct compression.

It should be a prerequisite to have these skills:
Basic tools and knowledge assembling/disassembling motors
Electrical knowledge and soldering ability
Access to someone that welds or your own ability to weld! If you can weld aluminum that will come in handy for the intercooler piping!

These are lists of items that are easily attainable by the average person. All setups should have the Air to Fuel Ratio verified on a dyno with wideband or at very least on a track using an in-car wideband setup (NO watching the standard O2 signal and calling it good). If your using pump gas and seeing air to fuel ratios more lean than 11.8:1-12:1, some rethinking on the tuning/fuel setup will be needed. A narrowband guage(typical A/F guage from Autometer for instance) is not complex enough to be a real indication of the ratios inside your combustion chamber.

Heres some links to some good widebands. These will give you an idea of exactly what your car is doing air/ fuel wise. I run the digital innovate mtx-l and I love it, and it has definitely saved my ass.
I also run a cheap ass knock sensor gauge tapped in to the stock sensor. If you have an apexi safc2 it has a knock feature so you don’t need this.

with that done, what kind of parts are you going to get?
I know a lot of you want to look real good turboed and show worthy, so here goes- for the manifold, stick to top mount to have clearance. A bottom mount turbo manifold for a 240sx isn’t going to work

JGS makes a great manifold that fits our trucks very well, the downpipe almost works as is, it might need slight modification. This is where I got my oil feed and return lines and manifold. His stuff is great quality
for fancy stuff and fancy intakes and cams you can go to these guys, they know ka-t’s
now for the cheap stuff that a lot of 240sx guys have had good luck with. The manifold needs some spots strengthened so it doesn’t crack, but its decent. If you run the turbo they supply, plan on buying a quality new or used garret or oem turbo soon-the turbo don’t last long, but the rest of the kit is decent.

as for the intercooler piping, you gotta get creative. I got a cheap set of ic pipes for a 240sx on ebay and cut and added couplers as necessary. Then I found a good but smallish intercooler I could fit in the bumper. Voila.

now lets move on to the builds

Very Mild Build: around 180 rwhp

Turbo Manifold
Blow Off Valve
Turbo (T25)
Downpipe 2.5" is perfectly fine
Pipe to connect turbo to throttle body

Fuel Control:
Wideband o2
FMU (not recommended, but doable) Raises fuel pressure per boost to make injectors flow more than normal.
DSM 450cc Injectors or Comparable (These injectors are low impedence, while the ECU requires high impedence. Making it necessary to wire in resistors to alter that so the ECU can control them. These can be found at places found at the bottom)
Apexi SAFC2
Greddy Emanage

Mild power adder, say you want around 200 rwhp.

wideband 02
Turbo Manifold
Blow Off Valve
Small Intercooler (potentially get away with a side mount)
Turbo T25/T28/14B, etc. Smaller T2 setups. Usually will be internally wastegated.
Downpipe 2.5" is perfectly fine
Replacing the Exhaust is starting to be very necessary at this stage, so I would start to shop for that as well.

Fuel Control
DSM 450cc Injectors
Apexi SAFC2
Greddy Emanage
Back off base timing at distributor or MSD BTM

Average: 300 rwhp to 350 rwhp, you have to start to expect a little more lag. This is about the perfect "street car" limit. No race gas, just good honest street car fun that is fully capable of bring home a 12 second timeslip on a good run.

Turbo Manifold
T3/T04E .50 Trim compressor, .60 trim compressor housing / Stg 3 (aka TA31) turbine wheel, .48 to .63 A/R exhaust housing. External wastegate recommended.
Downpipe can still be 2.5", but this is as far as I would want to push that.
Front Mount Intercooler (FMIC) It's time to upgrade to a larger front mount as the larger intercooler will push more air than the smaller intercooler can cool.

Fuel Control
550cc Injectors
SAFC2 to control your fuel injectors, along with the stock ecu.
MSD BTM At this stage I would be running the BTM to control timing retard.
Reflashed ECU-This can be a DIY thing with Eprom Tuning or a JWT. This is the largest JWT is capable of flashing for those that want it.
Z32 Maf is required, as the stock Maf stops being able to read at around 260 rwhp.
Wideband O2 Sensor should be installed for tuning.

Block Internals
This is where I would start to consider it necessary to replace you pistons.

Above Average: 350 rwhp to 425 rwhp

Turbo Manifold
Blow Off Valve
T3/T04E 50 Trim .48/.63 or slightly larger turbo, this is where I would start to make the switch up to an external wastegate. You have the option to reroute it back into the exhaust, or merely "dump" it out into the open. "Dump" is usually a mini exhaust in the form of 1.5" piping routed out to the open.
FMIC Larger is starting to be necessary. Typical for setups from here on, are 12"x24"x3" for the core.
Downpipe 3", at this point I would switch to the larger downpipe. You can probably get away with it at 2.5", but it will be causing a little bit of backpressure. Moving to 3" piping as quickly as possible is what you want though. If you run the JGS manifold you will have plenty of exhaust clearance.
Exhaust 3"

Block Internals
At this stage you'll want to "build" or fortify your block to better handle boost. Previous to this you can walk the line, but here and forward I find it necessary to do so.
Forged Rods
Forged Pistons
Stock Crank
Plus your typical rebuild items.

Fuel Control
Standalone fuel management is recommended at this stage in the game and is absolutely necessary at the next. These allow you control not only very large injectors, but the tuner to have complete control over both timing and fuel.
720cc Injectors.
Wideband O2 Sensor is necessary for tuning.

With that said, here is some links to some more info:
Maximum boost by corky bell. Its old but it’s a great read for turbocharging info.

Another turbo book

Jgs turbo’s hardbody truck build
nis720’s build- sick ka24e running nistune engine management
bendiesel’s turbo megasquirt hb
ka-t setups (incuding schmauster’s, a very good time tested daily driven setup)

that’s it for now. I hope this inspires people to get out there and turbo their trucks! if anyone has any info to add or share please post it up!

Gordo78 02-27-2013 02:36 AM

Awesome man. Thanks for taking the time to write this all up!

eddie402 02-27-2013 05:34 AM

I vote sticky, could be helpful to a bunch of people!

7odd 02-27-2013 06:32 AM

^^ agreed. sticky it up.

very well written.

heh, i just picked up a turbo and a 240 intake...i was about to start making my "parts needed" list...well, look who just wrote it all for me.. :)

Bubba 02-27-2013 10:30 AM

Ya'll need to sticky this!

alabama_lowlife 02-27-2013 11:21 AM


nis720 02-27-2013 08:42 PM

FYI... the CX racing manifold is not recomended. Wastegate flange will eventually break from the heat and the thin material. It also places the turbo way too close to the valve cover and will fry spark plug cables. JGS or similar manifold works best.

Motorhead 02-28-2013 02:38 AM

Thanks for the heads up nis720 I know that some guys were having good luck with some of the cheap eBay manifolds. Which ones were they? The SS autochrome ones?

What about the do-it-yourself manifolds on eBay?

Motorhead 03-01-2013 04:19 PM

This is a conservative rating at 3 bar. * indicate side feed inj sizes that can be bought from Nissan, Nismo or Tomei. Alot of the sizes you can not get but are there to help you if you are looking at a cetain flow rate by going to 4 bar.

3 BAR = 44 PSI, All the Nissans with Fuel Presure Regulators operate at 3 bar.

4 BAR = 59 PSI Running at 4 bar is better than running at 3 bar. Here is why, you can get more WHP from your inj at 4 bar, there is no xtra cost for a 4 bar program from JWT, you get better drivability at 4 bar because of better fuel atomization and you car will do better at the emmisions station becasue of better fuel atomization.

All Nissan Side feed injs are high impedence

The GTIR 444cc Inj is low impedence

91-99 USDM SR20DE = 259 cc side feed injs
00-02 USDM SR20DE RR = top feed injs

U12, U13, W10 and W11 SR20DET = 370 cc Side Feed injs
Pulsar GTIR SR20DET = 444 cc Top Feed injs

S13 and S14 RWD SR20DET =370 cc Side Feed injs
S15 RWD SR20DET = 444 cc Side Feed injs

SR20VET = 444cc Top Feed
SR20VE 20V = 350cc Top Feed

Side Feed Injs

23 cc = 16 WHP
46 cc = 31 WHP
93 cc = 63 WHP
139 cc = 94 WHP
185 cc = 125 WHP * Pink GA16
231 cc = 156 WHP
259 cc = 175 WHP * Red or green SR20DE -also the sidefeeds on hardbodies 96-97
278 cc = 187 WHP
324 cc = 218 WHP
333 cc = 226 WHP * Grey SR20VE
---------------------------------------------333 cc @ 4 bar = 261 WHP
370 cc = 250 WHP * Purple SR20DET
---------------------------------------------370 cc @ 4 bar = 290 WHP
416 cc = 281 WHP
444 cc = 299 WHP * Brick Brown SR20DET ( S15 )
---------------------------------------------444 cc @ 4 bar = 345 WHP
462 cc = 312 WHP
509 cc = 342 WHP
520 cc = 348 WHP * Yellow Subaru STi side feed
---------------------------------------------520 cc @ 4 bar = 400 WHP
555 cc = 373 WHP * Yellow
---------------------------------------------555 cc @ 4 bar = 423 WHP
601 cc = 405 WHP * Yellow Tomei
---------------------------------------------601 cc @ 4 bar = 457 WHP
647 cc = 436 WHP
692 cc = 468 WHP
740 cc = 500 WHP * Red
---------------------------------------------740 cc @ 4 bar = 580 WHP

850 cc = 570 WHP SARD
---------------------------------------------850 cc @ 4 bar = 660 WHP

Nissan Top Feed Injs

270cc - stock red injectors on obd1 hardbodies and 240sx sohc cars

350cc = 275 WHP * Green SR20VE 20V P12

444cc = 299 WHP * Yellow RNN14 GTIR

444cc = 299 WHP * Yellow SR20VET

MSD Top Feed Injs

36 lb = 250 WHP
50 lb = 355 WHP
72 lb = 520 WHP
96 lb = 690 WHP

MSD Injs do not run right at 4 bar so don't try it.

nis720 03-01-2013 10:00 PM


Originally Posted by Motorhead (Post 326791)
Thanks for the heads up nis720 I know that some guys were having good luck with some of the cheap eBay manifolds. Which ones were they? The SS autochrome ones?

What about the do-it-yourself manifolds on eBay?

The only one i considered just for the sake of trying it was the CX Racing one because of where it places the turbo is ideal for a truck setup. So I have no idea who else makes one that would fit our trucks. I also considered the Gladman one, but it seems to put the turbo on the steering assembly.

My next step is to have a custom one built.

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