Dsmguy1993

Hi guys okay so Ive owned a 240sx in the past but it was all stock. Long story short I have a 89 hatch with a redtop sr20 ecu transmission and harness already inside it and I have a quick question to the veterans and you experienced guys. Would I be better off piecing together a redtop sr20det? Cylinder head, block, intake manifold wiring harness turbo etc? Look I only ask because I wanna use a wiring specialties harness I already have a tomei expreme turbo header so I wanna cut out uneccessary stuff I do not want a full swap if I dont need it does that make sense? If you guys can help thats be great thank you. I ask because the full swap on ebay and in general is pretty pricey.

Kingtal0n

If you have ten years of building engines experience and combine the service manuals notes with some updated materials of course it would be a wise investment to build your own engine, even a stock one.

However many people lack the tools and experience


so you gota ask yourself. Do I feel lucky

oiling orifices in modern engines are so small the slightest bit of grit glob clogs a passage, ruins the engine.
If you buy one thats been exposed to atmosphere. Lets say I have a running engine and take it apart all oily inside, and I set it on a table top and leave it there for years.

After a year or two the sheer quantity of debris buildup inside the engine due to time and atmospheric entropy, interaction with myriad content and natural tendency of forwards reactions such as oxidation when exposed to long term storage/exposure as in this example renders the engine block useless forever. After just a short period of time environmental ingredients attack and stick to and alter the surfaces of an engine's internally exposed materials because they are intended to be sealed up with very clean oil, sealed perfectly away from the atmosphere and a wide variety debris. You can't just clean an engine thats been improperly exposed to certain conditions so being very selective is the main point when choosing a block with intention of rebuild and high mileage. Likewise never use an engine which has already had a catastrophic failure unless absolutely necessary.

In short, if you find an engine and intend to rebuild it, make sure the engine has never been open to the air (for very long), and has as much of track record for oil changes (visual indicators may help determine maintenance) and when you go to rebuild the engine if you have enough experience you will learn to use a clean room, air filtration, and build it as quickly as possible, then seal it up very tight and keep the oil clean using high quality filtration and pcv systems.
Novices can get away with slight rebuilds by following the service manual exactly and making sure to start with an already good running engine. But thats a different story than trying to piece one together... IF you got a running one that needed a rebuild with clean oil and no abnormal wear, it would be ideal as a novice to simply swap the bearings/rings hone and go, with no machine work and close cleaning attention to detail. However where will the novice acquire a cheap, running, high mileage sr20det engine without any issues or abnormal wear.... That was not the question being asked and doesn't seem cost effective, merely easier and higher chance of success. Which actually might make it more cost effective in the long run since failure rate is empirical for the person asking, I guess it still comes back to experience because exp leads to mistakes and If you've never made certain mistakes with sr20 engines (or any engine) You are bound to make them for the first time on the first attempt....

Many have tried building the sr20det engine, there are many mistakes to make

https://zilvia.net/f/showpost.php?p=6285960&postcount=4

Dsmguy1993

That was very well said I do agree with you as well there are many mistakes to make and insane amounts of room for error. With that being said in regards to the oil orifices being clean is that not what the machine shop takes care of? Perhaps im wrong but I thought thats what hot tanking and cleaning the block does? Now I got some experience working on engines I redid my own timing belt in my 4g63 turbo water pump etc but this would be my first actual rebuild if I did do it. I should clarify as well when I mean piece it together I dont neccesarily mean cheap out per say I would pay to get machine work done on the block and get it cleaned and make sure the crank gets looked at as well. Perhaps that is a lot of work altogether and I may even be better off just buying a swap from someone I dont know because I dont know about sr20det but I want to learn as much as I can before I put money in so I know I am making the most educated decisions.

blkvrtswp

Buy the full swap to get the warranty - then sell what you don't need. Buy something that does not need to be rebuilt. Rebuilding SR20's is for over 500 WHP goals or after you have spun a bearing. Many many paths to failure in rebuilding SR20's. PS some machine shops SUCK BALLS - find one with proven SR20 experience. Good luck.

Kingtal0n

This is what I am saying, if you choose an engine which is NOT currently clean and running well, there is a very high chance the machine shop will 'clean it' and it will NOT be cleaned properly. The rebuild will fail quickly. For example if you find a motor that lost a cam lobe and then a rod bearing. Let me tell you how that happens, first the oil orifice for the cam lobe fails because a tiny, less than 1mm of carbon crust is all it takes, lodged in the hole permanently and that melted the cam lobe quickly. The metal washed through the engine and took out the oil passage for a rod bearing and started taking out the next one and so forth.
You can take that motor apart and try to clean it. You can take it to three different machine shops and have each of them clean it. It will still spin bearings for the rest of its life because nobody will ever put the full time and attention required to remove every bit of debris, its "impossible".

If you let a block sit exposed to the atmosphere for very long, it becomes un-cleanable in a similar manner, because every tiny bit of organic carbon life form from the air (fungus, pollen, bacteria, tree materials, skin, the air contains everything and there are something like 200,000 particulate per square not-so-large volume) is just as deadly as metal particulate to engines with the only main difference that when metal finally sticks down its under a significant pressure or trapped in a space, whereas organic carbon is gooey and smaller particular may tend to stick wherever it feels like or to an already growing pile of itself somewhere (atherosclerosis, coalescent carbon chains of fat as in cell membranes), and the organic carbon can react vigorously in the high temperature and pressure of the engine's oil and internal combustion. In many ways air exposure is more deadly to an engine than metal particulate, when we consider all the potential reactions with engine oil and combustion byproducts (pollen for example contains myriad constituents as: potassium, iron, sulfur, calcium, molybdenum, sodium, the elements of life) that are available.

Oh sure, the machine shop will take it and 'clean' it for you, but that doesn't mean anything because it is typically a very basic approach and there is very little inspection or attention to detail spent. There are changes that the atmosphere makes to exposed metal surfaces which may be slight at first but ultimately reveal themselves as permanent damage.

If you want to see the actual surface of the engine insides it takes microscopy, severe attention to detail, surface samples, oil orifice camera elapse footage, fluid dynamics for entry/exit of flow over journals, etc... there are thousands of influences inside the engine oiling system which a machine shop will NOT care about, they will likely NOT take the necessary time, potentially hundreds of hours to fully inspect and clean a highly "filthy", externally exposed engine or for testing and modifying existing oil passages for high performance nature. They don't consider that part of 'cleaning' the engine yet under any real racing conditions where winning was an absolute must, of top importance, yes the entire engine internally is inspected and dynamically challenged to meet the strictest of specifications, and that means not one little tiny bit of goop is inside one of the oil passages. Its up to YOU to clean every channel/orifice/hole and make sure the oil moves smoothly and completely from one to the next as it should. This is the mistake many make: assuming the machine shop fully "did everything" to clean and inspect 100% of the engine. And there are many who have been building engines for twenty thirty years still not really sure about how to fully achieve this. You can buy an engine, or assembly an engine, with the assumption the oiling system is perfect. But it rarely is and very few are actually testing the flow rate throughput in volume/time and modifying their pump and system to achieve the right flow range for each operating conditional.

jedi03

its not impossible, just takes more time than most shops want to spend...the sr isn't a one off engine that requires much "special treatment" but you do need to pay attention, measure accurately and don't just throw parts on it as you can have catastrophic failure. This is applicable to every engine type...i personally have rebuilt several of my own engines in less than ideal areas and have yet to have a failure...i have measured and taken extensive amounts of time cleaning all parts during assembly and while assembling making sure all parts are moving the way they should, just in case of over/under torqueing on bolts. However, even if you do everything right theres still potential for failure as there are many variables outside of our control...we can only mitigate by making sure to buy quality parts and do what we can correctly!

Kingtal0n

thing is you'll get some guys that say they build engines all the time without cleaning or measuring anything and do fine.

What they don't say is how many failures, what kinds of failure, what they've done to prevent failure, i.e. just because you build 100 engines and 78 of them survive doesn't mean the other 22 of them failed for reasons outside of their control. But that's how machine shops and builders often think "it wasn't the machine shops fault... prove it"

tell you what if you aren't getting a list of exact dimensions, sizes, specs, measurements, surface finish quality, weight, balance, and so forth back from an engine 'care' giver with every dollar spent then you have no idea what the $(@*#%$ is going on, what was done, or even what oil to use.

WOOTEN

So, let me ask this question from another perspective. Say you have an SR20DET with 40k on it that's been sitting in the engine bay for years. Do you look towards rebuilding with spec parts and no machine work? or do we just run the thing?

brndck

personally i'd pull the valve cover and oil pan, inspect as much as I could, put fresh fuel and oil, then run compression and leakdown

as long as those numbers are good, and the pump is making good oil pressure, fire that fucker up.

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nick_d_240sx

New fluids, turn it over by hand and make sure it rotates smoothly, fire it up, check for leaks, or any gas/burning smells and if all is good, RUN IT!

If you're not a machinist, or if you don't know a good one, you probably shouldn't be 'rebuilding' your engine. Proper clearances, tolerances and assembly are a must for rebuilding an engine.

I agree with Kingtal0n.

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1990 240SX SR20DET GTX2863R

WOOTEN

I have rebuild several engines, thought I have never tore an SR20 apart. In my career its always good to talk to the guys on the ground. Everything you guys said is what I was planning on doing. just figured it would be batter to ask for advice them not to.

I do believe your being hard on the machinist community. Why I agree that there are shitty techs out there in all fields. Most machine shops I know of do really good work, in there field. If your in a region that builds tractor engines, you probably wouldn't want them building your SR20.

With that said; does anybody have experience with any machine shops in the Nashville region that knows SR's

Kingtal0n

The sr20det never came to America. I think that is why its so hard to find a good machinist in America that does sr20det already for many years.

I can't name a single place that does good sr20 rebuilds. I tried a couple locals to me just out of curiosity, got the engines back in all out of sorts. One had the timing chain on wrong, and the wrong head/oil pan surface and leaked from the headgasket oil constantly. One forgot to put all the bolts back into the head and oil pan. A next one bled all of the oil OUT of the lifters and left them all full of air.

I mean holy shit this stuff isn't even that hard. Forgetting bolts? You don't need to be an sr20 expert to not forget the bolts. But there you go

Have had some friends with success, but we are talking fully built forged pistons and head work, 5-10k engine rebuilds. That get barely driven. I think one has close to 3000 miles on it after 4-5 years. So who knows how long its really going to last? It's not an accurate comparison to say "yeah I had an SR built ten years ago and its fine" because that might only be 10k miles, but thats the sort of thing people are going to tell you when you ask where to get your engine build "I had mine built at so-and-so ten years ago and it's been great" (but I only drive it once a month)

If the engine has low miles then all the above advice is great, oil it up, turn it easy, clean it the best you can all reachable areas but don't take it apart. Just run it. Compression test and if compression is low it might just need the valves cleaned, they get hard carbon buildup and then stick open.
Remember while it sat some of the valves were open and there is a very high chance the surface coating of carbon is 'mobile' think of an amorphous solid, so over (long period of) time it sort of 'dribbles' slowly into positions where normally the valve wouldn't allow it to rest because on a running engine the valve is constantly being shut harshly against the seat which drives the sealing surface 'flat' as carbon is malleable, it can be quite soft and gooey, or very hard like a diamond, you get all in between which is why cleaning is sometimes necessary (cleaning with a knife by hand for example I've done)

The engines don't "go bad" when they sit unless they sat open the atmosphere.

brndck

Bluemoon in costa mesa is excellent
http://bluemoonperformance.com/

obv that doesn't help the dude in Nashville, but there ARE engine builders who have excellent attention to detail, and plenty of small shops like Corner3 in Irvine that wont cut corners either.

what I've found is lots of people will want to ask "how much to rebuild my engine" (which is dumb as fuck, theres a million variables that will dictate the cost) and shitty engine builders will throw out a dollar amount, just to sucker you in to agreeing to the work

a legit engine builder will tell you "we have no idea until we tear down and inspect, and can verify what parts can and should be reused, and what cannot/should not". Good engine builders will charge a teardown fee, which will be credited towards the total cost of the build, if you choose to have them complete the job.

if someone just says "oh it'll be $x.xx to 'rebuild' your engine", be very skeptical.

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WOOTEN

it may just be me, but I generally always build my own engine. that way I know its down right. that said; I dont have the skill set nor the equipment to machine a damn thing... lol

jedi03

rofl that's a recipe for disaster! but if you go in understanding something may fail due to inexperience that's different than trying to build a vehicle you need to go 100k with little to no issues...but i agree you never know unless you do it yourself...but imo its less expensive to get a full jdm swap and just run it...

Kingtal0n

In the near future I want to try it. Piece together an sr block and clean the living F out of it. Assemble using mostly FSM and oem parts if necessary. I'll rent the dial bore gauge and indicator tools to make sure its round with a deck plate strapped how I want to run the head and compensate in fastener torque if necessary for slight deformation, if it even makes a difference. Its not 1000hp so I don't need special O-ring or head gear. Stock head gasket would even work but I would just use a cometic or typical multi layer steel. You don't want a strong head gasket on a daily driver build, just in general, but I won't have any tuning issues so I am not afraid to use MLS. If I was unfamiliar with the application I would def use OEM HG though, first.


Avoid the machine shop by dealing with the cylinder walls and ring selection personally, or find another block. I would weigh the cost of new blocks against success of finding good blocks, against the cost of using OEM pistons with existing blocks. If we give it some extra budget, I'd like to find an OEM +/-0.00XY style drop in forged piston like they have for LS engines with easy to hone at home, skip machine work. After accurate measurement, call the various companies and ask I guess. "do you carry SR forged for drop in OEM cylinder? Ya what is cylinder wall recommended clearance... uh-huh and how should the cyl walls be prepped for those rings? What is alloy of piston?" collect data see if you can make it work.
Then Simply measure and look for perfect fits by chance. It sounds crazy but I think the piston will be a little tight by design which allows for hone to take some 1 thousandth give or take. Before purchase make sure the manufacturer is willing to work with you on sizing somehow (if I get a piston that is .0008 too tight can I send it back for a re-fit, etc...)
Its a tedious process but if you manage to calculate correct piston-wall clearance for each correctly to fit with the required cylinder wall finish given the type of ring provided, it would work as well as if any machine shop did it in theory. I would def do your own calculations based on piston alloy and high temperature, i.e. (mechanics of materials) expansion coefficient to find out total diameter in bore at high temperature 2200*F 2500*F 3000*F etc... for that alloy and starting diameter. Find the margin of safety/error in piston'wall clearance or find how the piston manufacturer came up with that number (ask?). Sometimes you can run a less expansive forged piston alloy tighter. The manufacturer is assigning some number based on max temp so to err on the cautious side (since nothing is perfect) which way will you go, just under or just over? For my daily driver, I would be under, but a racing application would be over. A racing application wouldn't use an low expansive alloy though. So it depends on how the manufacturer approaches the problem of stock bore sizing in daily vs racing applications, do they offer STD bore forged piston in a high expansion alloy? (they actually do because you can buy brand new blocks sometimes, summit sells them for engines with new blocks available, but they are labelled as "street friendly" alloy which I have to wonder at) And if so, how many thousands less in diameter will it be than the stock unit. And then there are .005" larger forged which I presume is for weathered OEM bore with mileage, hone it just right and you have a forged piston with no machine work needed in the bore.
Balancing is the issue and actually getting a good hone (could take more or less than you wanted), many potential failure spots hidden I am sure. I would likely just use OEM piston.

Then try to get 100k+ out of it with ~500rwhp

I think it's entirely possible 1 person does everything including tuning and has enough experience.
Hopefully thats the message the first post is sending

IMO
even with 100year experience and super mechanic skills, stuff just goes wrong sometimes. There is a luck involved in many aspects. Do not attempt if you don't feel lucky

Dsmguy1993

Yeah you guys rock man I def agree with talon up there when you say sr20DET never came to america and therefore you cannot rebuild it with just traditional engine rebuilding theory. For example the crank is nitride coated and is a very tight tolerance thats why if you ever machine an sr20 crank(which i would never do I would buy a new nissan one) you seriously have to take off very very little and recoat it and thats expensive and it takes skill. Yes I agree as well I always like to get down to it myself and im well aware of plastigauge and coming to correct tolerances ive read books on engine building and ive taken classes in automotive I fixed my old dsm engine myself however that was not a true rebuild.
Okay guys I wanna run this by you I just picked up a red top sr20det with a spun bearing I dropped the oil pan and there were metal shavings and a torn rod bearing in there. Now I know that the crank and rods need to be replaced along with bearings and hell ill even do pistons and rings too but what scares me is can I really trust a shop to clean all the minute shavings out of this engine? Its just like KingTalon said LOOK HOW SMALL the jets are on the oilers for the cams.. if even a small metal shit was lodged in there that would be catastrophic! I dont mind spending money to rebuild it but Im just scared of can it be cleaned correctly again tbh idk what do you guys think? I paid 1500$ but I got apexi power fc wiring specialties harness a radiator a transmission and a power fc commander.. I wanna do this right though thats why im asking your opinion on this.

Dsmguy1993

I dont mean to double post but you are soo correct with that why should I pay 2.5-3k for some “jdm” engine I don’t even know about? If theres one thing I know about cars its you do it right once or youll do it again and buying a used silvia engine contradicts that if you think about it.

jr_ss

I’ve owned unopened(head gasket and studs) SR’s for years. I had one last 3yrs and 30k with me beating on it regularly. I was also sub 300whp on no tune. Stupid? Sure, but it had been done one more than one occasion.

Look, any SR you buy is already long in the tooth. Basic maintenance and repairs will be necessary. I suggest buying an entire swap to ensure you have every piece you need for the swap. You won’t save money buying pieces here and there. Not to mention, an assembled engine is less likely to have been fucked with throughout the years. There are shady people out there that will sell you a head that is worth nothing more than scrap prices.

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My SR20VET

Jorgs_7

Lol - The most long winded yet fantastic reply.

He is right. Do not bother piecing together. Buy an assembled SR20, likely from a local or importer. You wont save much money piecing together.

My 0.02 - Buy a known running SR20, keep it T2 turbo, under 17 PSI and you wont have to build the bottom rotating assembly.

nick_d_240sx

Uhm, one note, the SR20 isn't some magical engine. They've been built up in Japan since the early 90's. Build to specs.

180sx SR20DET FSM in Japanese

https://www.junauto.co.jp/machining/sr20.html

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1990 240SX SR20DET GTX2863R

Kingtal0n

As soon as I find metal the block is trash to me, doesn't matter what engine block (LS, 2J, SR, 4G, RB). The only way I would even consider using it is if that was the last block available and I desperately needed to build something. Like an original RB26 and it was my last block... they are expensive and I might consider trying to save it. But I wouldn't spend a bunch of money on parts for it just yet- rebuild it stock first put some mileage on it. 50k maybe you know drive it around everywhere. Then pull it apart and see how it did. Re-check everything. It shouldn't wear much if at all if assembled properly and clean enough. Looks good? then use it for a massive $$$ build after that.


You'll probably make a mistake on the first one which takes the engine out completely that has nothing to do with metal debris, but its still nice to have a failure and not say "Hmm I wonder if it was MY fault, or the previous failure that contributed" Because then you don't know if you did something wrong or not, you may repeat the mistake.

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Dsmguy1993

Yeah I definitely understand why you would not want to use a block if you found metal shavings inside of it and I never would either unless it was being rebuilt. So your saying you would not use that block even if a machine shop cleaned the entire block and it was running a brand new crank, rods, bearing, and pistons? In my opinion as long as u throw a new oem crankshaft rods and pistons in there with new bearings after a machine shop has fully cleaned it I see no issues. Thoughts?

Kingtal0n

i dont know dude do you feel lucky? let us know how it goes

not tryn to be a dick but you keep asking the same question my answer aint gonna change,

if you even have to ask, the answer is no

best odds with perfect application of mechanical skill i put 50/50 chance on it

but honestly when people tell you not to do something, sometimes you can do it, and get away with it (50% aint that bad, afterall), and rub it in their faces. So it's ok if you want to try and do that too because it fosters motivation, an idea of success, which is sometimes all it takes to get some in one form or another.

I get the feeling you really want to try and somehow think you need the permission of people on the internet to try... no need permissions to try guy

jr_ss

Kingtalon is a bit extreme when it comes to his expectations.

People have rebuild motors for years with great success. I personally would steer clear of any motor that had spun a main bearing. However, they can be fixed, but you need to find a shop that specializes in SR’s.

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My SR20VET

Kingtal0n

I just don't like taking chances that aren't necessary. Why use a potentially ruined engine block (49% chance) when you can still get a complete running swap and rebuild it using FSM (80-95% Chance) Or just drive it the way you get it (98%)

600hps14

the sr20det? is that like a thing around here?