SR20 Rebuild: how are these bores??

[RalliartRsX]

Well, I finally had a chance to tear ton a short block that previous owner clamed had no low compression. As seen, the cross hatch is very visible, but there seems to be some cylinder/bore "wiping" as well as heat marks at the very top of the bore.


I know its fairly diffult to judge just based off pics, but if the bores are still uniform top - bottom, can this be bored over 0.5mm/0.020 and be fine, or do you think a bigger overbore would be required??

Cylinder 4



Cylinder 1



Cylinder 2



Cylinder 3

[jr_ss]

Do any of the vertical marks grab a finger nail? Have you checked for out of round? Is that pitting in the last photo or just crude? It doesn't look like a bore/hone wouldn't fix said issues.

[RalliartRsX]

1) None of the vertical marks grabbed a finger nail, but I will check to confirm again
2) Nope, have not checked for out of round (but that is definitely on the to do list once it is fully torn down. This is just a preliminary check)
3) No pitting and just "crud". It actually flakes right off and the pistons clean up with ease

Thanks for the response. It seems a few other people share your same view: This should clean up with a .020 overbore

[Krusty_s13]

Should clean up fine. No crazy scoring visible.

[Kingtal0n]

it looks like every sr i ever took apart. main thing is roundness with hardware installed after any machine work.

on that note, i dont know of any machine shop thats ever given me back an sr20 i would assemble. I finally gave up after 10 years or so and just stick to stock longblocks, i put a cap on rwhp output around 350-380 and get 8~ years out of a stock longblock $1200.00 at that power level. If you want over 380 to the wheel use a 2jz or lsx, same deal, stock longblocks for 500-600rwhp are fine, the lsx being the cheapest option ($800 truck engine 5.3L from 04-06 is ideal).

[jr_ss]

Originally Posted by Kingtal0n

it looks like every sr i ever took apart. main thing is roundness with hardware installed after any machine work.

on that note, i dont know of any machine shop thats ever given me back an sr20 i would assemble. I finally gave up after 10 years or so and just stick to stock longblocks, i put a cap on rwhp output around 350-380 and get 8~ years out of a stock longblock $1200.00 at that power level. If you want over 380 to the wheel use a 2jz or lsx, same deal, stock longblocks for 500-600rwhp are fine, the lsx being the cheapest option ($800 truck engine 5.3L from 04-06 is ideal).

He didn't ask your opinion on what motor he should run at what power level. Move on with your broken record bullshit.

[Kingtal0n]

Originally Posted by jr_ss

He didn't ask your opinion on what motor he should run at what power level. Move on with your broken record bullshit.

U madbrah?

Yeah lets ignore statistical evidence and just go with our intuition

[RalliartRsX]

Originally Posted by Kingtal0n

U madbrah?

Yeah lets ignore statistical evidence and just go with our intuition

I agree with Jr on this. Technology has progreased very far in the last 20 years. I can riddle off 5 shops that use a torque plate to not allow the inconsistent bores.

Mazworx is in your backyard. They had a 1200 hp SR before going to a billet block.

Anyways, please kep this on topic. Thanks for the info king and Jr

[jr_ss]

Originally Posted by Kingtal0n

U madbrah?

Yeah lets ignore statistical evidence and just go with our intuition

I'm not mad "bro". You seem to think that people care what YOU think is an acceptable horsepower limit on a given block/motor. You interject your opinion every time someone asks a question related to a motor/setup/power goals and frankly it's tiring. Your "statistical evidence" is nothing more than failed builds parted out in the FS section. You had a bad experience with an incompetent shop, I'm sorry, but not all shops are the same. We get it, you like to keep it under a specified level, move on.

[hanzbrady]

Originally Posted by RalliartRsX

I agree with Jr on this. Technology has progreased very far in the last 20 years. I can riddle off 5 shops that use a torque plate to not allow the inconsistent bores.

Mazworx is in your backyard. They had a 1200 hp SR before going to a billet block.

Anyways, please kep this on topic. Thanks for the info king and Jr

1500hp.. Just saying

[Kingtal0n]

It isn't the bores, or the 'level'; it is the cost to failures ratio given a particular power output per unit mile. Around/after 450-500bhp or 600bhp the cost of the sr20 'built' far exceeds similar statistical ratios given a larger more robust, near stock engines at a tiny % of the comparison cost (i.e. cost to failures ratio per unit output/miles is significantly better when using a larger engine) as mileage increases above say, 20k to 100k.

And then you have the in between 380 and 500 crowd. You want 450? You will want a 'built sr20'- opening the same avenue for parts related failure that the 500 and 600bhp crowd has to deal with, with hundreds less horsepower. That is what I call the 'dead zone' where nobody should find themselves, a pointless grey area where other, larger stock engines are not only cheaper but tend to be more reliable.

I am only trying to save people headache and money. If a $800 longblock from a truck weighs 80lbs extra and exceeds the power goal of a $5,000 sr20 engine in the dead zone AND is statistically likely to give you many more miles (mileage = fun)... where is the logic behind using the 2.0? Unless you absolutely NEED that 2.0 for some reason (class or specific genre or personal desire) engines are just engines.

[RalliartRsX]

......and we're off topic lol

King, as mentioned, thanks for the input. I never once mentioned my power goals or end use of the engine, so not sure why you are making these assumptions or posts. I simply asked if the bores were good and the answer was received. Let's leave it at that. You have your experience and build and although apprevised is fairly outdated and antiquated information.

I refuse to trust any long block I pickup as quiet frankly, these enfines are almost 30 years old! Technology allows us ro rebuild stronger and more reliably and regardless of the experience you have had, IMHO is does not reflect what I have personally witnessed and experienced and is somewhat removed from reality.

Again, I very well appreciate the input, but I do have a certain pland in mind and I am going to stick to what I know works.

[Kingtal0n]

Originally Posted by RalliartRsX

......and we're off topic lol

King, as mentioned, thanks for the input. I never once mentioned my power goals or end use of the engine, so not sure why you are making these assumptions or posts. I simply asked if the bores were good and the answer was received. Let's leave it at that. You have your experience and build and although apprevised is fairly outdated and antiquated information.

I refuse to trust any long block I pickup as quiet frankly, these enfines are almost 30 years old! Technology allows us ro rebuild stronger and more reliably and regardless of the experience you have had, IMHO is does not reflect what I have personally witnessed and experienced and is somewhat removed from reality.

Again, I very well appreciate the input, but I do have a certain pland in mind and I am going to stick to what I know works.

by all means progress. However I would kindly ask that for the sake of our community you keep us updated with the progress and mileage of the engine as you use it.
I don't know anybody with 50k on a rebuilt sr20, or even 30k with an aftermarket bearing. Some people rebuild them and just don't drive them much. Many fail without any report; what you see "failures" is only a small fraction of what truly exists (many are too embarrassed) and we have quite a fair number of confirmed failures from folk who weren't too embarrassed.

Originally Posted by RalliartRsX

I never once mentioned my power goals or end use of the engine, so not sure why you are making these assumptions or posts.

As to this statement I think the anwer is obvious; everybody wants infinity horsepower as a goal. Nobody shoots for minimum power, that is upside down. You want the max you can squeeze given the constraints of the budget and materials available (parts and juices) and how far you intend to drive it (or how long), which is cost(budget) to failures(limits of materials) ratio given a particular power output(X is power, a variable approaching infinity) comes from, and we use miles (distance) as the unit of measure for how far the money, parts and power actually drives you down the road in a daily driver comparison (it can be converted to years or track days, for example, as a unit of measure for non-daily drivers)

[jr_ss]

Originally Posted by Kingtal0n

by all means progress. However I would kindly ask that for the sake of our community you keep us updated with the progress and mileage of the engine as you use it.
I don't know anybody with 50k on a rebuilt sr20, or even 30k with an aftermarket bearing. Some people rebuild them and just don't drive them much. Many fail without any report; what you see "failures" is only a small fraction of what truly exists (many are too embarrassed) and we have quite a fair number of confirmed failures from folk who weren't too embarrassed.

Track miles > Daily driver miles...

Ralli- What does your "budget" VE build consist of, less the obvious?

[zombiewolf513]

Originally Posted by jr_ss

Do any of the vertical marks grab a finger nail? Have you checked for out of round? Is that pitting in the last photo or just crude? It doesn't look like a bore/hone wouldn't fix said issues.

Wont it be out of round anyway because there isnt a head/torque plate bolted to it?

[RalliartRsX]

Originally Posted by zombiewolf513

Wont it be out of round anyway because there isnt a head/torque plate bolted to it?

Technically yes. However, the FSM has tolerances for three measurement spots along the bore, so if they are within FSM spec, then the assumption is once you bolt the head on the tolerances will be tightened up.

[240KA]

what are some other techniques that machine shops should be using while working on these SR blocks (probably applies to other blocks too)?

so far i've learned:
1) make sure to use a torque plate when honing or boring out the cylinders

[jr_ss]

Aluminum blocks tend to distort when you apply torque to the fasteners. A torque plate and a bell housing would ensure you have all axis covered. I'd also verify the mains/girdle are in place as well, if possible. However, that may be on the extreme end. If I'm not mistaken Mazworx uses only a torque plate.

[RalliartRsX]

Originally Posted by jr_ss

Aluminum blocks tend to distort when you apply torque to the fasteners. A torque plate and a bell housing would ensure you have all axis covered. I'd also verify the mains/girdle are in place as well, if possible. However, that may be on the extreme end. If I'm not mistaken Mazworx uses only a torque plate.

x2. I think after a certain bore they just just resleeve the blocks

240KA: Also, to keep in mind; you have wet vs dry sleeves and FWD SR guys when they were sleeving for 90mm were having the sleeves drop because they were dry sleeved.

But that is a whole other story in itself. Mazworx has done the process and is very versed in doing this.

[hanzbrady]

Originally Posted by RalliartRsX

x2. I think after a certain bore they just just resleeve the blocks

240KA: Also, to keep in mind; you have wet vs dry sleeves and FWD SR guys when they were sleeving for 90mm were having the sleeves drop because they were dry sleeved.

But that is a whole other story in itself. Mazworx has done the process and is very versed in doing this.

To just explain some of what we do,

1) ALL blocks, not just aluminum are machined with a torque plate and all main hardware assembled to ensure the block stays in spec.

2) ALL blocks are cleaned after every machining process and allowed to fully cool down to ambient temperature before any further machining or quality control

3) A torque plate isn't removed from a block until final QC or assembly.

4) All forms of QC are double checked by two separate techs to ensure no mistakes get by

5) Most importantly ALL work is done in house with no outsourcing which leads to less chance of miscommunication and opportunities for mistakes to be made. All work is performed on CNC machines operated by trained professionals who've been working exclusively in the racing industry for years.

As per the sleeve comments, after 87mm we will sleeve blocks, 87mm is the "safe" limit for an SR before heat soak and cylinder wall distortion become a failure point.

Also all SR20 sleeves are "dry" sleeves, as the block can't physically accept Darton's wet sleeve (MID) meaning that once you sleeve an SR it's permanent and ruining a sleeve ruins the block. For this reason all machining on sleeved blocks is proprietary so that we can eliminate any failures associated caused by 3rd party actions. Also since the sleeves are permanent for SR's we often recommend going with a smaller bore size such as 86mm or 87mm simply so you have room to mess up because you can go up all the way to 92mm, however; that requires custom pistons. By leaving yourself several bore sizes available your block lives much longer.

[RalliartRsX]

Originally Posted by hanzbrady

To just explain some of what we do,

Also all SR20 sleeves are "dry" sleeves, as the block can't physically accept Darton's wet sleeve (MID) meaning that once you sleeve an SR it's permanent and ruining a sleeve ruins the block. For this reason all machining on sleeved blocks is proprietary so that we can eliminate any failures associated caused by 3rd party actions. Also since the sleeves are permanent for SR's we often recommend going with a smaller bore size such as 86mm or 87mm simply so you have room to mess up because you can go up all the way to 92mm, however; that requires custom pistons. By leaving yourself several bore sizes available your block lives much longer.

Thanks for clearing that up. I was reading up on Darton and found that, yep, their sleeves are not accepted by our AL blocks if wet sleeving, and that also may have been a failure mode (as compared to wet vs dry sleeving). From what I understand, the FWD guys were not using your process at the time