Exhaust and Turbo confirmation and suggestions.

[fresh tulip]

Just need some clarification, found out for my build I will be running on my pistons chart of 15-30lbs of boost for the hp (and also so my builder knows the proper gaps and clearances) I want. Just deciding on the exhaust manifold and turbo I should get. I don’t care about lag, but don’t want to be holding the throttle down forever, but boost creep and lag seem kinda fun. I have looked at a lot of exhaust manifolds go the rb26 and a lot look shitty or have stupid straight pipes from the manifold. This one seems decent but has 2 wastegate flanges which I guess is nice, idk. It is a twin scroll t4 which is nice and looks pretty good. The turbo which I legit briefly looked at after googling “good t4 turbos” is this borgwarner one as listed. How are my choices? Will they work? Any better suggestions?

Turbo https://turbochargersdirect.com/new-genuine-oem-borgwarner-171702-turbocharger-for-detroit-diesel-series-60-12-7l-replaces-garrett-tmf5502-tur-100025-bwn/?gad_source=1&gclid=Cj0KCQiA5fetBhC9ARIsAP1UMgHoW6sKNPoh03vrotHKmppC8JhYbqwpkHUOt7eX9uHQvbxk216qXdUaAnaGEALw_wcB

Manifold https://jackspaniaracing.shop/products/rb20-rb25-rb26-det-t4-top-mount-turbo-manifold-for-nissan-gtr-44mm-twin-scroll?variant=44432444326113&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gclid=Cj0KCQiAn-2tBhDVARIsAGmStVln-sU8a0dUkcjqTNNp_TSZ3dOXmNwjPA1yfhpEdDEiTz2Ff_GXyKAaAi3JEALw_wcB

Thanks for any advice or suggestions 😊

[left quail]

So first, like I tell pretty much everyone in here, figure out what boost is.

[fresh tulip]

Air being forced into the cylinders

[left quail]

No. What does that boost gauge measure

[fresh tulip]

The higher the boost the higher the amount of air being forced

[left quail]

If the engine is an air pump what is boost?

[left quail]

You're getting closer

Sorta

[fresh tulip]

The engine in NA can only suck in a certain amount of air. A turbo being added onto the engine adds an additional amount of air

[left quail]

And the excess is ____?

[fresh tulip]

Dumped

[left quail]

Broder

Boost is just a measure of restriction and the restriction depends on everything from the turbo to the cam

So you find out how much air you plan to move at your power goal and build around it.

[fresh tulip]

Doesn’t the wastegate help regulate the pressure? Is it a problem having two?

[left quail]

Depends on the setup

Some will use every bit of air the turbo can give it and won't need a wastegate, on the other hand too much restriction can need two wastegates

[fresh tulip]

Ya 15-30lbs of boost is what I need for my setup. 20lbs will get me the power I want

Is the turbo too big or something

[left quail]

So figuring off of the stock cam?

[fresh tulip]

No

[left quail]

So who figured up the cfm ?

[fresh tulip]

Are you asking how I got the boost number for what I will be running?

[left quail]

Yes

[fresh tulip]

I took multiple different builds on the internet similar to mine and averaged them out. None of them were lower than 15lbs

[left quail]

If you're going to do that pick a tried and true setup and copy it to the tee

[fresh tulip]

I want 500whp at the beginning and 650whp when I upgrade my tranny

Went through similar builds and there

[left quail]

If you want to give me every bit of info on the engine I can figure out exactly what you want when I get home and can load up the analyzer

[fresh tulip]

Aight good luck finding a similar build; but sure. Rb25de with eagle rods and wiseco pistons 8:4:1 87mm. Supertech valve train +1 and tomei cams (can’t remember the spec on those but probably getting forged cams; just wanted them for the break in month to test the cam caps). the cylinder head intake is ported same with exhaust and intake valves. The combustion chambers on the head will be widened and expanded to get rid of the sharp edges and provide a lower comp.

The cylinder head is an rb26 btw

Bottom block is an rb25de

If it is a too big of a turbo you got a better one

[left quail]

So, since I don't know the Nissan stuff worth a damn I need
Cam specs
Bore and stroke
Valve size
Rough estimate on what the head flows (really should consider putting it on a bench if you want to blueprint something)
Intake and exhaust manifold flow

[left quail]

Many, but "too big" is hardly ever the case

[fresh tulip]

Aight good

[fresh tulip]

I listed the pistons and the bore. Also goes to the chart above. Valve size is a +1 from the oem rb26. Forgot the cams, will have to did through my mail. It is probably still around a 2.5L with the bore.

I don’t know if I can give an estimate on flow without the porting being done

[left quail]

I can tell you that a 400 series is gonna suck for driveability, and a 300 would still make upwards of 850-900 chp and drive 10x better, just be a little hotter

[fresh tulip]

Awesome

Thanks, I will look at that one

[left quail]

400 series needs about 350cfm from the na engine to be worth a damn on a driver, assuming it can pull that at a driveable rpm

[fresh tulip]

It is a smaller engine so ya, I assume going for a smaller turbine would be better.

[left quail]

When I get home I'll plug it in the analyzer, it probably has the stock head specs on file

[left quail]

Who ported your head? Do you have a flow sheet?

Also need cam specs

[fresh tulip]

They haven’t started yet. Just gonna make the valve ports larger and the intake and exhaust to match the gasket. The combustion chambers will also be completely domed.

[fresh tulip]

I have done more research and I am set on the borgwarner 300 series as some people run them with stock cams and drop in cams with no problems

Looking at an airwerks 300sxe

My cams are tomei duration cams

Let me check, but I am only gonna run them for a month with the initial Break-in and then I am gonna go for proper forged ones.

So it doesn’t really matter imo

I did make sure they will work properly with my valve train and my turbo setup as I emailed the supplier my specs of my valvetrain