SR20DET build/project advice

[AceOfHz]

Hey everyone. A few years ago I bought my KA24E '90 240sx and finally brought it back to life after it had been sitting in a field for 10 years. When I bought it, a red top SR20DET in pieces also came with the deal.

The owner was in the middle of building it out and gave up mid way. He said the guy he bought it off of blew it up and he bought the blown engine. He also said he had the crankshaft balanced after he got it. The block came with the crank, rods, pistons, head on, valve train all put together minus cams. Otherwise it is all in pieces. I currently do not have any part of the intercooler set up, radiator set up, clutch/flywheel, or gauges.

Parts wise, it has Probe pistons, eagle rods, ARP head and main studs, BC 264 cams, BC springs and retainers, some brand of 3 layer metal headgasket, stock turbo that needs rebuilt, and rocker arm stoppers. Also has Megan racing turbo manifold and ISR downpipe. Everything else is stock. Also came with a full OEM gasket set, all accessories, 2 transmissions, stock intake and exhaust manifolds, OEM harness and ECU.

This is my first engine build and turbo car. I have done low/medium level tasks on several cars, but have never done anything to an actual engine besides timing belts/chains and adjusting valves, so I am new to this aspect but do have half decent mechanical ability. At the same time I would be building this solo as I don't have any friends into this sort of thing.

All I want is a fun, streetable, (decently) reliable turbo car, I'm not looking to go super fast or race or drift competitively. I am wondering if I should just sell and part all of this out and buy an assembled stock SR from ebay or a JDM engine yard, or continue the build and go with what I have. Also keeping in mind I'm missing about $600 more in parts with the build I have. I paid $1000 for the SR20 part of the deal.

Any advice is immensely appreciated. I apologize for any ignorance, like i said, I'm new to this sort of thing.

[unicoder]

It all depends on your patience and how willing you are to learn. You can do this all yourself if you practice searching the forums. As EVERYTHING you need has either a thread or YouTube video already.

If you don’t want to, it’s perfectly fine just sell it and buy the swap.

My main advice is don’t take the previous owners word for anything. Rip that block apart and make sure it’s done right.

[AceOfHz]

I believe with forum and youtube info, I could assemble the motor. And you're right, I do need to disassemble the block and start from nothing just for peace of mind. He even gave me this old DVD called "Shift 180" that supposedly shows how to rebuild the engine yourself.

One of the main things I was worrying about is if all of the aftermarket pieces and forged internals would be overkill or even work together, but I already have them and from what I've been reading, they'll work to make the engine more stout and reliable.

I think at this point I'll start doing research on assembly procedures and maybe track down some sort of shop manual and just dig in.

[Kingtal0n]

built engines don't last long

SRs that built and failed quick

http://zilvia.net/f/showthread.php?t=535520


http://zilvia.net/f/showthread.php?t=569861

http://zilvia.net/f/showthread.php?p=5765974

http://zilvia.net/f/showthread.php?t=579996

http://zilvia.net/f/showthread.php?t=586960


http://zilvia.net/f/showthread.php?t=415523&page=2

http://zilvia.net/f/showthread.php?p=5951668#post5951668


I stopped keeping track years ago so this is just a small fraction


my advice is to use a stock engine. Stock engine list of HP support for daily drivers:
sr20det up to around 320-350rwhp
2jz-gte and LSx are 500-600rwhp capable daily

If you are dead set on a rebuild then do a STOCK rebuild and follow FSM procedure, and do NOT allow a machine shop to touch the engine. If you need something "cleaned" or "shaved" buy another identical part that doesn't need that work done, never send it to the machine shop. That's where most mistakes occur. You will wait weeks/months for something and it will be done wrong, and you won't even know it until it costs the entire engine.

[e30gangsta]

Find yourself a legit machinist that knows what he's doing. I've seen plenty of local sr cars make power down here that are "built". The difference is that they weren't built in some dudes driveway, also once its 'built' get yourself someone to properly tune the car. Goodluck.

[Kingtal0n]

I've never seen a built engine go even 20,000 miles

I've seen a properly maintained factory engine go 250,000 miles+

you get 90% more mileage from a factory engine, 90% of the time.

Part of the reason built engines are not friendly as daily drivers is their clearances are too large for frequent cold starts and cold driving. A built engine needs warmup "laps" where the car is driving gently for the first 30 minutes to expand internal engine parts and heat the oil up. Then for 20 minutes it can be driving harder to finish warming the oil to a full 210*F~ the process takes 40-50~ minutes for most engines to fully expand parts and warm engine oil.

And then finally it can be used near full power 500+ horsepower

If you don't need 500 horsepower+ from a 2.0L engine then there is no point using forged parts. ask me why


Another problem I've noticed, an sr20 with a large bearing clearance will put excessive wear and tear on the rod bearing #1 as it is the farthest away from oil pressure during a cold start. The motor ultimately fails gradually and rod knock #1 just from being cold started with a thicker, 'racing' weight oil. Which is necessary once the engine hits full operating temperature with such a large clearance.

[e30gangsta]

I guess dry sump it is then lol. there's plenty of vet sr's that have seen 20+k miles, I agree with most of what you are saying, but anyone who's trying to daily a 25 year old 500hp sr car is on a mission anyways. I know you've been in the game a long time, what do you suggest then for the rotating assembly? Do you know of a certain piston/rod combo that is currently available that its better than the "forged" stuff out there?

[AceOfHz]

So under further inspection of what was assembled of the block I bought, I found these two things that concerned me a bit.

Here it looks like an aluminum shaving, possibly from when they put in valve guides? Like I've said earlier, I'm new to this, but this looks like it could be bad news if left as in and ran. On the other side of the engine, another valve had a similar shaving, but much much smaller.

https://i.imgur.com/Uh5afXVl.jpg

Another oddity I noticed was that one of the spring retainers did not have any markings like the rest of the BC ones, is this anything to worry about?

https://i.imgur.com/1KI7GIhl.jpg

[derass]

Excellent posts from Kingtal0n.

I came here to say the same thing. But he went above and beyond proving evidence. Built engines never last as long as unopened ones from the factory. They're rarely built with the same precision. And OP's mystery motor in pieces sounds like a guaranteed failure.

I'd buy an unopened, running engine. And take that box of parts as a learning experience.

[e30gangsta]

Found a post in one of threads kingtalon linked. Bearing clearence's for future reference.

per FSM EM-94
Main bearing clearance
Standard 0.004 - 0.022 (0.0002 - 0.0009)
Limit 0.05 (0.0020)

Connecting rod bearing clearance
Standard 0.020 - 0.045 (0.0008 - 0.0018)
Limit 0.065 (0.0026)

Does Nissan still sell new sr cranks?

[CompleteXen]

built engines don't last long

SRs that built and failed quick



I disagree, I've built&machined and have many other friends who have forged piston setups that have been running and competing the past 4-5 years on their SR's with great success against what I've recommended to them. The key consistency was the tuner and never pushing their limits of the head/bottom end. Cams and springs were kept very mild if not stock, none went past 500whp. Many of these cars were and still are street cars.

At the end of the day though.. Stock is king. Rocking a .0015" clearance vs .0035+ will be better on skirt wear all day. You speak a lot of truth.

Ace, if you get it built find a good machinist who has dealt with these motors before and knows to go through and atleast check through everything. If that's not in the realm of possibilities than a stock, unopened motor is the route for you.

[CompleteXen]

So under further inspection of what was assembled of the block I bought, I found these two things that concerned me a bit.

Here it looks like an aluminum shaving, possibly from when they put in valve guides? Like I've said earlier, I'm new to this, but this looks like it could be bad news if left as in and ran. On the other side of the engine, another valve had a similar shaving, but much much smaller.


Another oddity I noticed was that one of the spring retainers did not have any markings like the rest of the BC ones, is this anything to worry about?



Looks fine for the most part, sometimes they rub off after repeated install/removal. For the shaving if could be from installing guides or resurfacing the head and just not cleaning it out properly.

Run air through all the ports, oil and water jackets in the head if you can and brake cleaner to try and break up any oil/shavings that might be in there before you do any assembly. Lots of machine shops don't care to go through and clean the engines before they send them off.

[jedi03]

if a built engine is built with care and precision it can last with care..i have seen several last...yes if they are horse beaten with cold start raced at 9k rpm then shut down immediately just like any thing they wont last, a factory engine wont either...anyone can show built or stock engine failures...do it right, take care of it and it will last. I sold my built sr that I put 10k miles on it to a friend to dailies it with another 10k on it. I moved to the Subaru world where there are several posts about built motors going upwards of 150k...yes several do break before then but several do last...im currently at 140k on a stock block but I also take care of mine with frequent oil changes, don't launch my car, keep it at redline all the time, good cool down time etc. so measure everything. do research on how to measure it do it right and take care of it then enjoy the car!

[Bnr32gtr]

Yeah I totally disagree about built motors don't last. That's just crazy I've had a built motor for over 10 year might be 13 dd it for 4-5 years beat the living crap out of it. I've also had sleaves sink causing h/g failure but it was my own falt for haveing a Machine shop install sleaves on a motor they were not familiar with. Do your home work on the parts u plan to use/ clearances that where it gets tricky from a stock rebuild to a hi hp motor.

[zenkicpe]

I can agree that a built motor can last, but as a general rule of thumb OEM engines are built to far better tolerances, esp for DD use. I think the same sort of thinking applies to V8's that muscle guys use. Some builders go the extra mile and match or exceed OEM, but most builders do not. I have a hunch $$$ separates the two.

350-400hp goals on a SR? Id much rather go with a clean unsealed OEM Nissan engine, at the most studs and a MLS. Just my opinion, which prob isn't worth all that much its zilvia after all lol.

[CompleteXen]

Keep in mind he was referencing cylinder wall to piston clearance, which heavily determines wear on the piston skirts. Larger clearances needed for forged pistons means that no matter what you have increased wear.

Cast with proper clearancing will last a hell of a long time (ignoring ring wear variables) 200k+ miles.
Forged with done right usually won't go past 60-80k, and thats a stretch.

[zenkicpe]

Certainly fair observations, good conversation to have

[AceOfHz]

Okay, so I'm learning these engines have super tight and strict clearances when it comes to pistons. Let's say whoever installed the previous ones did them wrong. Is it possible to buy new ones and reinstall them myself, ensuring the correct tolerances, and thus correcting an error that could kill my newly built SR? Or am I screwed since they've already been installed? My current pistons are 86.5mm (I read stock was 86mm), so I assume the piston walls have been honed out a bit to fit those and it's too late? The headgasket says its 87.5mm if that matters.

Thanks for all the input and responses guys, it's really really appreciated.

[derass]

Yeah, you would get bigger pistons.

And generally, you bore the block for larger pistons. Not hone. Boring removes notable amounts of material, honing instills the desired cross-hatched surface finish.

If you want to check piston wall clearances, you will need the appropriate micrometers and bore gauges. This process is called "blueprinting". As in recording precise measurements, and calculating the clearances, like an engineering blueprint.

If you want precision and quality, these are expensive tools. That's why it's rarely done, "built" engines are slapped together, and they fail.

[CompleteXen]

Okay, so I'm learning these engines have super tight and strict clearances when it comes to pistons. Let's say whoever installed the previous ones did them wrong. Is it possible to buy new ones and reinstall them myself, ensuring the correct tolerances, and thus correcting an error that could kill my newly built SR? Or am I screwed since they've already been installed? My current pistons are 86.5mm (I read stock was 86mm), so I assume the piston walls have been honed out a bit to fit those and it's too late? The headgasket says its 87.5mm if that matters.

Thanks for all the input and responses guys, it's really really appreciated.

If the PO fucked up the pistons then yes you can, you'll just have to stick with a .020" piston. If you can, have the blocks sizing and tolerances checked by a shop with some dial bore gauges. If you are going to install them yourself make sure you have the proper tools before hand.

Most forged or oversized pistons require ring cutting, and Id recommend you have a ring installer tool and a 86.5mm piston installer tool before going at it. Last thing you want to do is snap a ring during install on the piston or in the block.

Headgasket being 87.5mm is fine. Headgasket bore sizing is recommend to be slightly larger (.5-1mm) than your final cylinder bore.

[240KA]

some great information in here!!! awesome things to keep in mind when us OCD/perfectionist people want to rebuild a motor.

CompleteXen, i'm definitely gonna hit you up when i decide to rebuild an SR.

Find yourself a legit machinist that knows what he's doing. I've seen plenty of local sr cars make power down here that are "built". The difference is that they weren't built in some dudes driveway, also once its 'built' get yourself someone to properly tune the car. Goodluck.

but what's a "legit machinist"!?!? someone local who builds 1000hp Ford or Chevy engines or someone who has worked on SR's before? obviously would prefer the machinist who has done quite a few SR engines. it seems like if you want it done right, most of us will have to have the engine shipped out of state.

i don't keep up with SR news, but the first "legit machinist" that comes to mind would be Mazworx, but i feel as though that'd be an expensive route for a 300-350hp oem rebuild setup.

anywho...start listing some legit machinists guys!!

[derass]

Is it possible to buy new [pistons] and reinstall them myself, ensuring the correct tolerances, and thus correcting an error that could kill my newly built SR?

If the PO fucked up the pistons then yes you can, you'll just have to stick with a .020" piston. If you can, have the blocks sizing and tolerances checked by a shop with some dial bore gauges.


I hate to nit-pick, but tolerance and clearance are two different things. When building an engine, you're ultimately interested in the clearances.

[mewantkouki]

some great information in here!!! awesome things to keep in mind when us OCD/perfectionist people want to rebuild a motor.

CompleteXen, i'm definitely gonna hit you up when i decide to rebuild an SR.



but what's a "legit machinist"!?!? someone local who builds 1000hp Ford or Chevy engines or someone who has worked on SR's before? obviously would prefer the machinist who has done quite a few SR engines. it seems like if you want it done right, most of us will have to have the engine shipped out of state.

i don't keep up with SR news, but the first "legit machinist" that comes to mind would be Mazworx, but i feel as though that'd be an expensive route for a 300-350hp oem rebuild setup.

anywho...start listing some legit machinists guys!!

Mazworx, 5523, etc.

[lonewanderer]

keep it stock for reliability, if you want more power and want to upgrade the internals, then you can still do so while keeping it stock. Id opt for keeping those aftermarket rods and then using z32 TT pistons as they're 87mm stock

[AceOfHz]

Unfortunately most of the past posts talked me out of it and I sold off my block a few months ago. That does sound like a good point though, didn’t know that z32 tt pistons would work in that situation.

Regardless, thanks to everyone who posted for the advice. Right now I’m just sticking with my KA24E. So far I’ve done suspension and wheels. Was thinking 1uz or KA-T for the future once I think I’m good at this level.