DC2-ProdUcTiOnS

iTrader: (2)

Last night I was able to pick up a OBD1 JDM D15B!

Since my previous experience has been with B-series, Im def excited to see what these single slammers are all about....Ive seen some crazy numbers come outta these puppys, even with the stock sleeves!! My plans for the motor right now are to figure out my best route to go before I just jump into throwing parts at it....I already have my EJ6 that its pretty much done now that is my pride and joy for the time being, so this is going to be somewhat of a budget based build for me hence why I titled it mild, but reliable.

Some issues I have read into with the D-Series are that is has paper thin rods that are unable to hold any boost over 6-8 psi reliably. It also seems that the most common thing to do with these motors is the Vitara pistons. It came with a VX tranny which seems like people are saying is too long of a trans for boost?? idk, thats where you guys come in....So heres what im thinking about doing...lmk what you think. Also how reliable are the heads on these motors? Do I need to think about upgrading valvetrain??Or will it be able to hold 10-12 psi safely?

I want to get the motor built and running in the car and break it in a little bit before i slap a turbo right onto it, but im most definitely going to boost it.

On with the plans:

- Complete tear down of motor / Fully disassemble Block
- Bore to 75.5mm
- Re-surface
- Is the crank strong enough? Or does it need some sort of machining?

Im going to buy a kit for re-building the bottom end: which includes:

- FJ R Spec Custom Length JDM D15 I Beam Connecting Rods
- ARP 2000 3/8" Rod Bolts
- ARP Lube
- YCP Vitara pistons ( 75.5mm )
- Wrist pins and C clips
- Piston rings (Hastings or NPR)
- OEM Timing Belt
- Japanese Water Pump
- ACL D16 Rod Bearings
- KING D15 Main Bearings
- King D15 Thrust washers
- Full engine Gasket & Seals set
- Metal 3 layer Head gasket (approx .030 thickness)

.................................................. .................................................. .................



From there I will need to figure out how durable / reliable the head and valvetrain is. The compression I should be getting with that setup is around 8.1:1......


Also, ive always been a N/A guy so all the a/r and trim stuff with the turbos is all new to me. I see how people use a different turbo at a lower psi and make way more power? gotta read into it a bit more....


lmk what you FI guru's think of what ive got goin....again, im not shooting for an outrageous build....

thanks for the help!

Dc2

ChokolAwt

iTrader: (1)

your compression could be a little higher... anywhere below 9's and you get diminishing returns.


but it sounds like a pretty solid build. you dont need to upgrade the head if you dont plan on winding it out past the stock redline. do you know what size turbo you're going with?

also, most important question when building a turbo motor. what's your hp goal?

DC2-ProdUcTiOnS

iTrader: (2)

I thought the lower your compression was the better it will be for Turbo? again...FI newb here!!! Why does having lower than 9:1 provide diminishing results? Why is this bad??

Yea the stock redline is fine by me.....7500??? thats fine....if i wanna slap 9K, ill just drive my coupe with JDM ITR in it!!

i have NO idea what kind of turbo i should use....like i said, i saw some people using a different turbo at a lower psi making more power than another turbo at a higher psi with similar/exact setup.....still need to learn what would be best? any suggestions???

as far as a whp goal? idk, i have no idea?? would 300 be attainable with this setup with the right turbo??? i dont want it to spool really late....again im a total newb to the FI part of the game so i could be talking non-sense.....

also, i know that a big part of doing one of these builds is in the tune, but once i get this project started well get further into that!

DC2-ProdUcTiOnS

iTrader: (2)

bump

shifty35

The FJ rods + Vitaras is pretty much all you need for the block to handle 400+ whp.

For the head, I'd just upgrade the valve springs, and get whatever cam you need to reach your goal.

DC2-ProdUcTiOnS

iTrader: (2)

ive read that the JDM D15B cam is similar to some of the aftermarket ones?

is this correct?

again, this is a somewhat budget build, so if i dont have to upgrade the head that would be great....

shifty35

I'm using a JDM D15B cam in my Z6 + D17 crank. Bisi measured them. The D15B cam is identical to a Z6 cam in lift / duration, but has a slightly wider LSA, so less overlap.

DC2-ProdUcTiOnS

iTrader: (2)

what kind of Turbo recommendations do you guys have?


again like i said, im a complete newb to FI....

shifty35

What's the power goal? What will the car be used for? You want an all out drag turbo, or something more street friendly?

DC2-ProdUcTiOnS

iTrader: (2)

def street friendly....

DC2-ProdUcTiOnS

iTrader: (2)

bump...

Mutiny1

id probably recommend t28 turbo. the bigger u go on trim size on a small engine the longer your gonna be in turbo lag waiting for boost..

shifty35

Ditto on something in the GT28R / GT28RS size range. Puts you in the 300 whp peak neighborhood, with excellent spool / response and midrange.

For the 400 hp range, I'd say something like an Evo9 16g with a twin scroll manifold.

But none of those ideas are really budget friendly. If you want to save money, you'll have to make sacrifices.

blackeg

i just did a very similar build in my old jdm itr front eg hatch last year. i sold the car to a local and he painted it orange for some reason. look for it im sure you will see it around.


anyhow if the fjt rods are anything like the eagles you are going to have to notch the block a fair amount. on mine the main girdle needed more work than the block did.

that motor setup that you have listed + arp headstuds is good for 400hp or more, as was previously said. stock crank is fine, honda makes good cranks. i think a power goal of around 300 is better suited for what you want out of the car, as it will let you run a smaller turbo and have better response out of it. something t28 based will work, as will a straight t3 50,60 or super 60. i ran a mitsubishi 15t on mine, power was mid to upper 200 range on 15-17psi.


pm me if you have more questions

DC2-ProdUcTiOnS

iTrader: (2)

Turbo Lag =



i think i would like to be in the 250-350 whp range if possible....




I believe the FJT rods are already made to custom length and size for direct fitment....i will def check tho, thanks for the heads up....



Thanks for the responses guys!! Where would be a good spot to look for or pick one of these up?? Do i really want to go with a used turbo?? I know there can be issues like shaft play, bent fins, and f'ed up lines?? is there anything else i should look for? Or should i just go new....

so it seems like some of the recommendations have been as follows:

- T28
- GT28/GT28RS
- T3 50/60/ or Super 60

What size piping should i be looking to??



Also a lil update, I popped the valve cover and everything looked great inside....

the issue with this motor was that it was unable to be started by lack of ignition/spark....it seems like some mistakes were made with connection and some broken faulty parts were used and could be the culprit...

wiledwhitecivic

2.25" piping for your power goals.
If you get a used turbo with the wheels and shaft in good shape, you never know if the seals are blown out.
A rebuild kit on a journal bearing turbo isn't two expensive if you do it yourself.
You should be able to push 2" piping to 300whp with enough boost on one of those smaller medium sized turbo's.
Don't be afraid to have to take it close to 20lbs tuned for your goal.
A 2.5 bar map sensor would then be a good idea.
The heads can be real reliable if they aren't warped. A resurfacing is a good idea if you're not sure about it. The set up fee at the engine shop is way worth it after you've been through several head gaskets even with a half way decent tune. It doesn't take much to over heat the oil and spin a bearing on a d-series. 4, 3rd gear pulls is about all they can take before a cool down. The engine coolant won't even be hot and you won't even know it except oil pressure gauge readings dropping down.
I didn't see anything about injectors and a wabro255. You might want to look into a stg3 clutch and ex trans. Even the dx gearing is a bit slow unless you can't afford a trans upgrade.
Put a new fuel filter on there. It's a good idea to relocate the pvc hose from the black box with a slash cut to the preturbo intake or to a catch can.
Static compression from 8-8.5 is plenty safe for boost with out being two low and you're out of boost response is still good, given enough timing that can be safely added.

Aykayek

Do you still have the motor?

Freemananana

iTrader: (3)

Ya know, it's only been 2 years. I bet he does.

Schister66

Probably not...since this thread is 4 years old.