Sticky: DOHC Turbo For Dummies

Basic tech questions such as future setups, different turbo kits, car diagnosis, etc
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veilside180sx
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Sticky: DOHC Turbo For Dummies

Post by veilside180sx » Sun Sep 25, 2005 7:46 am

These are the Prerequisites to building a DOHC Turbo. Together we will go through typical setups from mild to extreme to reach the power goals you desire. These are lists of typically used 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.



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:
FMU (not recommended, but doable) Raises fuel pressure per boost to make injectors flow more than normal.
SR 370cc Injectors. These can be found at places found at the bottom)
Apexi SAFC2
Greddy Emanage


Mild power adder, say you want around 200 rwhp.


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
SR 370cc 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. Internal wastegate optional but not 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 will push more air than the smaller sidemount 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 Megasquirt Tuning or a JWT.
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. Usually it is necessary to have the first bend 2.5" to clear the steering shaft though.
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.

Wild Build: 425 rwhp to 600 rwhp. Lag is obviously going to be much more apparent, full boost isn't going to happen until around 4000-5000 rpms or so. Once spooled it will pull very hard.

Turbo Manifold
Turbo T3/T61/SC61 or GT35R seem to be the typical turbo's in the area. External Wastegate is your only option that should be considered.
Blow Off Valve You'll want a good performing more expensive blow off valve to alleviate reverted air when the throttle body closes from pushing against the compressor wheel.
FMIC the 24"x12"x3" Core's are still effective in this range.
Downpipe 3" is still capable of handling these power levels
Exhaust 3" or larger

Fuel Control
720cc-1600cc Injectors
Standalone Fuel Management
Recommeded to switch to Map instead of Maf for reading airflow.
Wideband 02 Sensor installed and wired into standalone for adjustments and monitoring.
Dyno tuning is very valuable.

Block Internals
Along with the previously mentioned internals I would add these to the list
Cams (per your discretion)
Build your head as well
Valve Springs
Valve Retainers
ARP Head/Main Studs
Cometic Headgasket or similar


Absolute turbo necessities...amongst the aforementioned goodies above.

Oil Lines (Picture of good return location)
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Fuel Pump:
The stock pump is decent but not intended for such use. For Walbro 255's being as cheap as they are, anyone turboing their vehicle should upgrade previous to turboing.

Boost gauge

Here's lists of aftermarket products that are currently on the market

Turbo Build Parts:

Turbo Manifold (Exhaust Manifold)


Ground Zero Motorsports

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Full Race

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Peak Boost (release date TBD)

Revhard

Turbo240.com

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JGS Precision

Realnissan.com

Import-AutoPerformance.com

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Nizzx.com

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SSAutochrome (not recommended)


BOV

Tial
Greddy RS
JGS
HKS SSQV

Wastegates

Tial

Image

JGS

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Turbonetics

Block Internals

Pistons: Can be accomplished one of two ways, by purchasing ones that are made for the E with their intended compression ratio. The other is to use DE pistons and subtract a full compression point to equal the difference between the E and DE head. (ie 9:1 DE pistons will be 8:1 in an E)

Arias 8.8:1(DE)
Wiseco 9:1(DE)
JE 8.5:1
Ross 8.5:1(DE)
CP 9:1(DE)
Supertech 9:1

Rods: Any rod that will fit the bottom end of the DE will work with E as well.

Crower
Pauter
Carillo
Eagle (release tbd)

Bearings

Whatever your preference is for rebuilds. Mine is Clevite.

Headgasket

Cometic

Valves

Supertech Dual Valve Springs
SI Valves
Ferrea Valves

Retainers

Supertech Titanium Retainers

Cams

PDM Racing
Nissan Motorsports
Colt Cams
Crower
JWT Technology


Typical Injectors Used on DOHC

SR 370cc Injectors

SR Upgrade Injectors are available in various sizes between 550cc-720cc as side feed, anything larger usually you'll want to switch to a top feed fuel rail and injector combination.


Injector Resistors (To alter low impedence to work with a high impedence ecu)

JWT Technology
JGS Precision
Last edited by veilside180sx on Fri Sep 30, 2005 12:40 pm, edited 1 time in total.
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hmong337
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Post by hmong337 » Sun Sep 25, 2005 8:47 am

WOW! this is exactly what i needed to know... nice thread!

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Post by katdude » Mon Sep 26, 2005 6:49 am

nice. great starter project. helped a lot, too bad im leaving today
leaving for San Antonio in less than a week, the 27th to be exact,
for USAF basic training. Then off to Sheppard AFB till March for tech school. Should be fun!!!

95 corolla 5spd
ka24de s13 coming as soon as December. add the t with the coming summer.

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Post by rocky2843 » Mon Sep 26, 2005 10:19 am

great thread man...very informative....but for around the 300-325 range...how would a phatka-t gt32 compare to a t3/t04e??
IM in NJ. I can take you money and punch you in the nuts equally as good. Your gonna want to steer away from BD.--onefast240

^at this point iced tea shot out my nose and onto my dog..Gotta love being from Jersey

veilside180sx
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Post by veilside180sx » Mon Sep 26, 2005 10:50 am

It should produce very comparable numbers as a .63 turbine housing T3/T04E.
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Post by Slick Nick » Mon Sep 26, 2005 11:41 am

Great post, this will help me out A LOT with my engine rebuild!!! Much appreciated

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Post by jrivera » Tue Sep 27, 2005 5:47 am

thanks rich, awesome post :D

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Post by WesK » Thu Sep 29, 2005 6:50 pm

i agree.. i wont be collecting parts for my build up until feb/march of the coming year ( ill have 4k) but still.. this is a great read and i will be looking on it for certain things. appreciate it!
I <3 My S13

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Post by LumXingXing » Mon Oct 03, 2005 8:35 pm

great post. Thanks a lot :D

can we give suggestions or pictures so u can update it?

veilside180sx
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Post by veilside180sx » Tue Oct 04, 2005 6:37 am

If you want to give me suggestions for additions, do so through PM's
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Post by TIREKILLER » Tue Oct 04, 2005 1:30 pm

Very good thread, even if it is a little (ok alot) biased toward the T3 flange.

Add the pertinent info on 300 HP T2 flanged setups and this would be a very comprehensive thread.

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Post by veilside180sx » Tue Oct 04, 2005 4:56 pm

There are very few KA guys that run T2 based turbos. Most that do are SR crossovers, that now run KA's.
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Post by TIREKILLER » Wed Oct 05, 2005 8:15 am

I dont think thats very true nowadays. Considering the advancements in the availability of T2 flanged turbos, there are a few very viable options. Being able to use readily available parts (for SR aplications) makes installs much easier and more accesable to less experienced (or financialy/schedule challenged) people. I have never had an SR, **** i hadnt even driven one till last Sun. Yet Im puting together a 300 HP KA-T using a GT2871R. For drifting I think it will yeild a good usable power range.

Still a great thread, good job.

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Post by Hynes » Sat Oct 08, 2005 4:15 pm

The one you called "Mild power adder" how much psi would be pushing? 3-6? I'm trying to build a "cost effective" system for a autoslalom car that would be boosting 5-6 psi and I can get a good deal on SR injectors just trying to figure out if these will be enough for my set up. Or if I should go for a set of 450-550's?

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Post by veilside180sx » Sat Oct 08, 2005 4:32 pm

370's would suffice at that power level. On a smaller turbo it would be probably 7 psi.
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Post by Hynes » Sun Oct 09, 2005 1:29 pm

Excelent! Thanks for posting that too, answered a few of this Dummies questions :lol:

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Post by ninty1s13 » Thu Oct 13, 2005 10:24 am

thanks for the post, it helped alot..but with a t25 could i run 8-10psi..with an IC of course and will the 370's be safe at that boost level?Where can i get oil lines and what turbo manifold should I run with the basic basic set up?

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Post by vietdood » Wed Nov 16, 2005 1:57 am

great post! gave me my first step on how to build a turbo but there's so much more to learn

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Post by Stay KA » Tue Dec 06, 2005 3:51 pm

Grasiouso now how much boost is enough boost :oops: probably would of blown a engine :lol:

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Post by lopro240 » Mon Jan 02, 2006 5:49 pm

what kind of boost level's are we running to achieve these power numbers???

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Post by nissanfanatic » Mon Jan 02, 2006 6:38 pm

^Depends on what kind of setup you run. You will be capable of running higher numbers if you have a more efficient setup. Lower boost means less thermal/physical stress on the engine.
-Cory

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Post by lopro240 » Tue Jan 03, 2006 9:43 am

yes, i understand that. but there are horsepower numbers listed, but just curious at what boost levels, i could have all of those modifications and only be running 7psi, and achieve no where near those numbers or be right in the range, thats why i was just curious if you had an estimated boost range to achieve each power for each setup

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Post by vrmilionzx » Tue Jan 03, 2006 12:12 pm

lopro, i have no problem with you, but you need to do your homework. rather than asking vague questions, you should either
A) do more research, look at other people's setups and numbers
or
B)give a specific setup you had in mind, along with management and turbo trim, then ask for a rough estimate on output/boost level required for desired output.
i have noticed a lot of people suddenly signing on and asking these questions without doing much looking of their own.
don't get me wrong, you are reading this thread, which is a good start. just make sure you get more specific.
arias pistons (8.8:1), pauter rods,
cometic headgasket
garrett t3/4 50 trim
mild p&p, pdm cams, 3" turbo back,
jwt flywheel and ecu, clutch specialties clutch
740cc injectors, ebay fmic,
elec fans, msd, stock vlsd, z32 brakes and mafs, safc2, hks evc 4, Koyo Radiator, protective layer of dirt.
-"stock" s13 dd - Project MPG

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Post by lopro240 » Wed Jan 04, 2006 2:15 pm

i understand what your saying...i've done my homework. I was just saying that all that thought was put into telling you what kind of setup to run to make this kind of power, but boost levels were not listed...i was just trying to say that they should be included in the sticky to give noob's more of an idea. not looking to start any fights just thought it was something that i thought should be included in the forum for turbo dummies, hence the title dohc turbo for dummies

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Post by vrmilionzx » Thu Jan 05, 2006 10:18 am

hey, it's all good. i lurked on this site for at least 6months, and waited until i actually had a ka-t to join......
you have something of a point in that no boost levels are listed, but based on the trim (and size, if the one listed is not being used) of the turbo, the management, and just about any number of different inputs will change the output. manifolds are listed, but which one will also have some effect on spool and output. the problem is that adding a boost level for the general setup is difficult. the boost level would deffinitely depend on the turbo (obviously), but a good tune will make more power on less boost, so dependant on the management and tune, you could almost go with a slightly smaller turbo.
to put it simply, stating a boost level is very difficult for a generalized sticky like this, becuase then if someone tries it, and their setup is not as fine tuned as the writer, they will sign on and say "i did what you said, and it didn't work"
not to worry, i am hard to offend, you can pretty much call me an idiot if you want. it's the internet, i don't take it personally :wink:
arias pistons (8.8:1), pauter rods,
cometic headgasket
garrett t3/4 50 trim
mild p&p, pdm cams, 3" turbo back,
jwt flywheel and ecu, clutch specialties clutch
740cc injectors, ebay fmic,
elec fans, msd, stock vlsd, z32 brakes and mafs, safc2, hks evc 4, Koyo Radiator, protective layer of dirt.
-"stock" s13 dd - Project MPG

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Post by fogdor » Fri Feb 03, 2006 10:17 pm

Hey, since this is a dummies thread, I'm gonna ask a dumb question.

Are manifolds built for S13 and S14 ka24de's incompatible with each other?

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Post by modzilla » Fri Feb 17, 2006 11:49 am

good write up.. read up on it a while ago when i was first thinking of going boost.. and I still go back to it every now and then just to brush up while shopping around for parts.. just wanted to say thanks for the help.. aiming for the 300-400 HP mark.. ETA: 6-2006
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Post by Ham » Sat Mar 04, 2006 8:58 pm

Thanks very helpful. In the process of cleaning parts then off to HRT for work.

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Post by Chozen » Sat Mar 11, 2006 8:44 am

I am a FWD SR guy about to get an S13 that already has a KA-T. It only has an FMU, stock injectors, and an inline high volume pump. The turbo is a T25/T28 ball bearing. My question is, are the 370 injectors from the FWD SR's compatible with the KA fuel rail and injector clips? Could I just swap in a set of 370s installed in their rail onto the KA? Im pretty sure all nissan stuff is interchangeable, I just want to get an idea.

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Post by dopefish » Wed Mar 22, 2006 8:55 pm

The purple side feed injectors are compatible with the KA rail and harness.

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