Rebuilding an SR20DET (talk to me)

[BlackZenkiS14]

Ok, so I havent done the compression check yet (tomorrow morning), but Im 90% sure I burned up the rings in cylinder #2 on my S14 SR20DET. So Im going to need to re-ring it at the least.

I am on a budget, and will not be BUILDing this motor. As long as the block/cylinder walls are clean enough (pretty sure they are), im going to use factory pistons and rods.

I plan on having the blocked either honed or punched out .10 over, .20 at absolute most. Putting new rings on pistons, reconditioning the cranks, entire block with new freeze plugs, etc...full machine work to get the parts like brand new.

Then put it back together with an Apexi Headgasket and ARP Head Studs, and throw some Greddy rocker arm stoppers while its apart.

The car will never see a turbo bigger than a 2871R (.86), and wont be expected to make over 365whp ever, and doubtful even that high.

Is there anything Im forgetting or should plan on adding to this rebuild?

[Sileighty_85]

You cant bore out the cylinders and slap in new rings you need to get over-sized pistons to match the new bore other wise you'll do more harm than good.

[BlackZenkiS14]

Well actually, from what I understand from the local machine shop that rebuilds many SR's, you can do up to .20 over with factory pistons and get rings to compensate. However, your right, best case scenario, I will just hone to block instead of bore.

[R_G]

You will need to get the correct RA for a metal head gasket. IMHO it will be cheaper to get a block. s14 blocks are around 500

[D.Adams]

ok i just did my motor 5 months ago. I did all oem pistons - rings - rods with a hone it is not safe to bore .20 and run oem pistons and bigger rings to make up the .20 thats a easy way to get ring blow by. if you are on a budget like i was i would do a hone and oem internals. Have the head decked or shaved 20 thousandths and port and polish the intake and exhaust thats all stuff you can do yourself while youre working on the head have the valves re-seated again something you can do yourself. Also if you want to save $50 just get the C/S rocker arm stopers there just as good as greddy / hks .

just my 2 cents

[BlackZenkiS14]

Your right on man. Ideally I will hone it, and use factory stuff. I dont want to punch it either. I am also doing the rocker arm stoppers from Greddy as well.

Compression numbers:

#1: 133/120
#2: 52/50
#3: 126/120
#4: 134/126

[codyace]

As said above, you can't bore a motor and use factory pistons (well factory pistons @ factory bore).


If you don't ever plan on making big power, I'd say you'd be best of swapping in another used bottom end and going from there. By the time you buy new bearings, buy all new rings, get another pistons, and then install it all, you could have been already up and running with another OE block found in the classifieds.
If you're doing all of the work yourself, then I'd roll new bearings in the bottom end, re ring tha

[jdm213]

you may also want to replace the turbo seals and put steel braided lines

[BlackZenkiS14]

Already have braided lines. and Its a ball bearing turbo, so no replacing seals.

[wrxkyle]

is there a way to tell if you will have to re-bore with the head on still? like with a boroscope down the spark plug hole? i have low compression, front of car to back its 115, 110, 110, 105 (105 closest to firewall) did a compression test at two shops and got the same numbers so i don't think that it's an error in the test. would be nice though if it was...

i'm hoping to be able to hone and not have to bore, but who knows.

[D.Adams]

Originally Posted by wrxkyle

is there a way to tell if you will have to re-bore with the head on still? like with a boroscope down the spark plug hole? i have low compression, front of car to back its 115, 110, 110, 105 (105 closest to firewall) did a compression test at two shops and got the same numbers so i don't think that it's an error in the test. would be nice though if it was...

i'm hoping to be able to hone and not have to bore, but who knows.

you can rent one of these from home depot.. Why go through all the hassle hunting down a scope when you got to take the head off anyways. You got to measure the cylinders to make sure there not ovaled if you are going to do a rebuild. A hone will do in most cases if you had fucked up walls you would get real low numbers like 0-30. how many miles on the motor and how beat is it that all plays into what your looking at. When i re built my motor it still had the OG OEM hone marks i only rebuilt it due to the fact i dont trust allmost anyone when it comes to motors.

Toolmonger » Blog Archive » Starrett’s New Inspection Scope

[wrxkyle]

Originally Posted by s13bdafocker

you can rent one of these from home depot.. Why go through all the hassle hunting down a scope when you got to take the head off anyways. You got to measure the cylinders to make sure there not ovaled if you are going to do a rebuild. A hone will do in most cases if you had fucked up walls you would get real low numbers like 0-30. how many miles on the motor and how beat is it that all plays into what your looking at. When i re built my motor it still had the OG OEM hone marks i only rebuilt it due to the fact i dont trust allmost anyone when it comes to motors.

Toolmonger » Blog Archive » Starrett’s New Inspection Scope

yah, to all questions about the motor, who knows, can't get a hold of the guy that built it, the kid i bought it from was an idiot (the mbc was run from the wastegate to the intake, no, not intake manifold, the intake. between the mafs and the turbo, no hookup to boost, anywhere. enough said) i'll check on the HD thing, sounds like a good idea. i know i'll have to check but i'm trying to see how long i can put it off, because when i do build i'll be too tempted to drop a couple grand and do all new internals, but i'm only going to be running a 2871r .64

[NewfoundlandDude]

Interesting to see this on an S14 SR20det.
I did the exact same thing (cyl #2)and had about the same compression numbers with the same turbo last season.

Is Cylinder #2 a "hot" cylinder for the S14 sr20?

[D.Adams]

Originally Posted by wrxkyle

yah, to all questions about the motor, who knows, can't get a hold of the guy that built it, the kid i bought it from was an idiot (the mbc was run from the wastegate to the intake, no, not intake manifold, the intake. between the mafs and the turbo, no hookup to boost, anywhere. enough said) i'll check on the HD thing, sounds like a good idea. i know i'll have to check but i'm trying to see how long i can put it off, because when i do build i'll be too tempted to drop a couple grand and do all new internals, but i'm only going to be running a 2871r .64

Sounds like your having fun. i hade the same thing bought my car from a kid that didnt know anything about it. I have had to do allot to it to get it where i like it now. When i did my motor i only spent a lil over $700 for my OEM pistons / rings / connecting rods / full gasket set / arp studs. If your only going to run a 2871r oem internals will be good.I wouldnt run your motor longer than 10,000 miles with those compression ratios. You run the chance of doing more bad than good...

[BlackZenkiS14]

Originally Posted by NewfoundlandDude

Interesting to see this on an S14 SR20det.
I did the exact same thing (cyl #2)and had about the same compression numbers with the same turbo last season.

Is Cylinder #2 a "hot" cylinder for the S14 sr20?

That is interesting. What ended up happening with yours? Just bad rings? or did you melt a piston?

And what did you do to fix it? What was your rebuild like?

[NewfoundlandDude]

I ended up breaking a chunk off my piston (JE 86.5mm), which damaged both the head and bore. I got it re-bored to 87mm and bought CP pistons, but ended up buying another engine for this year.

Build is here.
Project NL S14 - Nissan Road Racing Forums

[BlackZenkiS14]

Well, I havent torn into it yet, but the way its looking, Im just gonna end up buying another short block and slappin it on It sounds like i'll need to repalce pistons...etc...and I just dont have that kind of money to make it happen.

[teamsprock]

My advice is as Cody said, but a used block. Most of the time you will never get a rebuilt engine back anywhere near as well balanced as a stock block. Also don't waste your money on RAS. No need for them at all.

[mct3351]

Lots of misleading information.
Your ring lands are cracked. Both the one between the first compression ring and the one between the second compression ring and the oil rings. If there was a hole in a piston your compression in the failed cylider would be 0 psi. I am almost certian the rings themselfs will look fine. This was caused by excessive knock/detenation that could have been caused by a number of things. The cracked ring land will most likely be on the intake side.

You absolutly can NOT oversize a bore without an oversized piston, your piston to bore clearance would greatly exceed the limit. Your only option from the OEM oversize perspective is a one time 0.20mm (.0079in) oversize. This will also require an "oversize" ring set.

Do NOT have the head or the block resurfaced if it is not needed (ie. check with a straight edge per OEM FSM). You can not put that material back on in the future. FYI the OEM limit is a COMBINED 0.008in from the head and block. If more is removed this will require a thicker than stock (1.1mm) headgasket to keep the compression ratio down (stock ratio 8.5:1). You would not believe how fast the compression ratio rises as material is removed from the head and block. Also if you remove more than the OEM limit it will alter how tight the "squish area" is and the rest of the combustion chamber geometry and it will alter the cam timing since the cams are closer to the crank shaft. If the engine has never seen excessively high water temps and is not warped of scored/gouged a resurface is not needed. NOTE: When cleaning off the stock gasket make sure to not gouge/scratch/score the mating surfaces of the block and head.

My advise, if you choose the rebuild option, would be to disassemble the engine to gain access to the failed piston. Replace the failed piston ($50) with the size stamped on the deck. Put new rings in it ($105 for all 4 cyliders). Have a machine shop lightly hone at least the poped cylider to remove any aluminum deposits from the "floating ring land pieces". You shouldnt need to bore it out. You'll likely see light "scoring" in the cylider that can NOT be felt with you finger nail and that should be taken care of with the hone. Put new OEM bearings in it according to the sizes indicated by the markings on the block and crank (~$110 for rod and mains). Buy the complete OEM gasket kit ($124). Replace the head gasket with an OEM one if you never intend to take it apart again and dont resurface anything. Buy an Apexi if you plan on a "built" rebuild in the future because the stock headgasket is a pain to remove (leaves behind gasket material on the head and block that is a pain to remove) or remove more than the OEM limit resurfacing a warped head/block. There will be no performance advantage to an Apexi HG at sub 400hp numbers. In all likelyhood all tolerances in the engine are within the limits of the manual as long as the motor was decently taken care of. You'll have around $400 in parts(w/o shipping) plus what the machine shop charges for the hone into it and it will be in better shape than it was in before the ring lands broke.

[bb4_96]

^ Took the words right out of my mouth

[SxMachine]

I would also stay oem on head and main bolts if your hp goals are low. Especially if your staying oem with your internals. Nothing wrong with a complete stock rebuild. If you do want a decent head/main bolt upgrade just go gtir, they're a bit stonger than the oem sr bolts

[S14Serge]

Having the same problem as the op, and didn't consider just getting a used block!! After it's all said and done with the rebuild you could have the car up and running and save some money will your at it. Good advice codyace!

[BlackZenkiS14]

Well, found out I need new pistons, so CP pistons it is.

Yep, it was exactly what I thought it was going to be. Smashed/broken ring land on my #2 cylinder. Pistons will be replaced by forged CP pistons/rings.





Motor is completely disassembled, organized, and is being brought out to ET Tuning for machine work, and rebuild tomorrow. Will be a fairly factory rebuild. Plans are: Apexi metal headgasket, ARP headstuds, Greddy Rocker Arm Stoppers, and CP Pistons and rings. Hot tank, cylinder hone, freeze plugs, etc...

Very excited to get it back in my hands soon!

[fliprayzin240sx]

So how bad is the cylinder wall? Are you gonna have to bore it out or a fresh hone gonna be enough to clean up the walls?

[spools420a]

Originally Posted by BlackZenkiS14

Well actually, from what I understand from the local machine shop that rebuilds many SR's, you can do up to .20 over with factory pistons and get rings to compensate. However, your right, best case scenario, I will just hone to block instead of bore.

That has piston slap written all over it,Dont do it Just oversize the pistons with the bore and whoever told you its ok to put factory pistons in a bored cylinder is absolutly incorrect that pistons gonna slap into the cylinder walls.

[spools420a]

Originally Posted by NewfoundlandDude

Interesting to see this on an S14 SR20det.
I did the exact same thing (cyl #2)and had about the same compression numbers with the same turbo last season.

Is Cylinder #2 a "hot" cylinder for the S14 sr20?

It should be,Thats the cylinder that would always break ring lands on turbo 420a engines when there was a slight hint of detonation,I'm so glad I moved from working on those pos engines.But yea It seemed cylinder #2 was always the weakest link.

[BlackZenkiS14]

Originally Posted by spools420a

That has piston slap written all over it,Dont do it Just oversize the pistons with the bore and whoever told you its ok to put factory pistons in a bored cylinder is absolutly incorrect that pistons gonna slap into the cylinder walls.

Yea, I agree, I decided to go with Forged pistons anyways, so we will see. Hoping to keep factory bore and get away with just a hone, its at the shop now, so they are going to make all the measurements and see what will be needed. But you can see all the factory crosshatching in the cylinder walls still, only a few straight lines in number 2, no scoring or gouging at all, still completely smooth. A cylinder hone should take care of it, but wont know til next week.

[BlackZenkiS14]

Welp. That was shortlived on the new motor

[jr_ss]

What happened to make it short lived?

[Sileighty_85]

sounds like you should find another shop