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Old 06-06-2018, 02:15 PM   #26
Lankku
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I wouldn't build that type of an engine under 8.5:1 compression ratio. 9:1 would still be ok. The lower it is you lose in driveability, fuel economy and the engine wakes up later. It's all about the tune.
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Old 06-06-2018, 02:22 PM   #27
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Went and picked up the engine block today, all nicely cleaned, bored and honed and he surprised me with the pistons, turned out he was able to source a Wiseco FORGED piston kit for the same price as original pistons, nice, brought a smile to my face. Need to do a couple things to the block, like deleting the stupid pcv, and then it's time for reassembly.
Nice! Now you need a set of HBeam rods!
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Old 06-07-2018, 05:06 AM   #28
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If by "a lot of boost" you mean, constantly over 30psi, sure maybe.

Nice pistons, I'd run a thinner hg and maybe skim off the head a little bit. Verify rod straightness of the rods. I'd personally just get a set of hbeams regardless and move on, but ymmv. These days, 9:1 is low compression, anything much lower than that is either very high output or just old.
Well, I do have a Holset HX35 sitting on the shelf, waiting to go in. I'm looking for h beam rods but it doesn't look promising. I actually drove my block to and from the shop in a WRX with (stock) 8:1 compression, that thing flies, even in low rpm it's pretty good. Would it really be so much different in a b230?

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Originally Posted by Lankku View Post
I wouldn't build that type of an engine under 8.5:1 compression ratio. 9:1 would still be ok. The lower it is you lose in driveability, fuel economy and the engine wakes up later. It's all about the tune.
My engine was 8.7:1 stock.

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Nice! Now you need a set of HBeam rods!
I know right! I'm trying to source them in a timely manner but it doesn't look promising. I think I might just put it together as is and check out the effect of the compression change. If I don't like it I'll have the shop machine the head a little bit and throw in H beams at the same time.
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Old 06-07-2018, 06:14 AM   #29
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I wouldn't build that type of an engine under 8.5:1 compression ratio. 9:1 would still be ok. The lower it is you lose in driveability, fuel economy and the engine wakes up later. It's all about the tune.
Mine is 8.5-1 I don't suffer any of those characteristics. Have you driven an 8.5-1 car to know what your talking about or just repeating what you've read on the all knowing internets?
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Old 06-07-2018, 10:15 AM   #30
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there's definitely a difference, it's not bench racing.

but you guys can go ahead and ignore 17 years of experience dealing with all types of volvo engines and do your own thing. I don't have to drive it or deal with it, not my problem if your stuff doesn't quite measure up ;)

I'm not sure I would use a subaru engine as a good example, they seem to lose pistons regardless of what the static CR is on otherwise stock turbo engines.

Rods can be bought off ebay, from vendors nearby (I'm sure you could get a set from sweden pretty quickly), etc. Might do yourself a favor at the same time and get the ones that convert to crank-steered vs the OE piston steering that goes on in b230s. No machining necessary.
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Old 06-07-2018, 10:54 AM   #31
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there's definitely a difference, it's not bench racing.

but you guys can go ahead and ignore 17 years of experience dealing with all types of volvo engines and do your own thing. I don't have to drive it or deal with it, not my problem if your stuff doesn't quite measure up ;)

I'm not sure I would use a subaru engine as a good example, they seem to lose pistons regardless of what the static CR is on otherwise stock turbo engines.

Rods can be bought off ebay, from vendors nearby (I'm sure you could get a set from sweden pretty quickly), etc. Might do yourself a favor at the same time and get the ones that convert to crank-steered vs the OE piston steering that goes on in b230s. No machining necessary.
I don't think I'm ignoring you, I very much appreciate you sharing your experience. That said, I think experiencing something yourself is very valuable and something you can take with you for life. So I think I'm going to try it and if I don't like it rip the head of and have it machined. Taking the head off is easy.

Good news, I think I found a UK supplier: https://www.maxspeedingrods.co.uk/hi...s-conrods.html. Will those bolt up, nothing else needed? Are these the ones that are crank steered?
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Old 06-07-2018, 11:56 AM   #32
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I don't think I'm ignoring you, I very much appreciate you sharing your experience. That said, I think experiencing something yourself is very valuable and something you can take with you for life. So I think I'm going to try it and if I don't like it rip the head of and have it machined. Taking the head off is easy.

Good news, I think I found a UK supplier: https://www.maxspeedingrods.co.uk/hi...s-conrods.html. Will those bolt up, nothing else needed? Are these the ones that are crank steered?
You can write and ask questions about the rods directly to Maxspeedingrods. They responded pretty fast the last time I asked them a question regarding their Volvo Whiteblock rods.
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Old 06-07-2018, 12:07 PM   #33
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I don't think I'm ignoring you, I very much appreciate you sharing your experience. That said, I think experiencing something yourself is very valuable and something you can take with you for life. So I think I'm going to try it and if I don't like it rip the head of and have it machined. Taking the head off is easy.

Good news, I think I found a UK supplier: https://www.maxspeedingrods.co.uk/hi...s-conrods.html. Will those bolt up, nothing else needed? Are these the ones that are crank steered?
It was not a response directed solely at you.

lemme go look, 24.8mm is something of a grey area in the memory bank. the length is correct. I'll go check in the archives and get back.
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Old 06-07-2018, 12:19 PM   #34
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based on some old spreadsheets I've got from the good oriental folks, 24.8 to 25.2 is what you'd be looking for for crank steerage.
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Old 06-07-2018, 12:39 PM   #35
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You can write and ask questions about the rods directly to Maxspeedingrods. They responded pretty fast the last time I asked them a question regarding their Volvo Whiteblock rods.
Email sent, thx.

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based on some old spreadsheets I've got from the good oriental folks, 24.8 to 25.2 is what you'd be looking for for crank steerage.
Thanks, nice. Does that mean I don't install the little end spacers that came with the Wiseco piston kit? The ones that go in between the rod and the piston.
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Old 06-07-2018, 12:58 PM   #36
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Email sent, thx.
Thanks, nice. Does that mean I don't install the little end spacers that came with the Wiseco piston kit? The ones that go in between the rod and the piston.
No spacers on the small end, if they rods are crank steered.
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Old 06-07-2018, 01:14 PM   #37
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Email sent, thx.



Thanks, nice. Does that mean I don't install the little end spacers that came with the Wiseco piston kit? The ones that go in between the rod and the piston.
if the rods are crank steered, you don't need them (but they wouldn't hurt either).
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Old 06-07-2018, 10:32 PM   #38
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Don't need a machine shop to tell you if it needs bored, just buy a set of telescoping guages and measure the bore in the thrust direction and perpendicular. Check against specs and make the call.
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Old 06-07-2018, 10:35 PM   #39
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Mine is 8.5-1 I don't suffer any of those characteristics. Have you driven an 8.5-1 car to know what your talking about or just repeating what you've read on the all knowing internets?
Higher compression ratio does result in more thermodynamic efficiency, meaning more power out of boost. Doesn't mean your car wont run with lower compression. Higher compression will be more prone to knocking meaning without a proper ignition map for the compression your ECU may pull timing and negate the gains from higher compression.
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Old 06-07-2018, 10:58 PM   #40
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Higher compression ratio does result in more thermodynamic efficiency, meaning more power out of boost. Doesn't mean your car wont run with lower compression. Higher compression will be more prone to knocking meaning without a proper ignition map for the compression your ECU may pull timing and negate the gains from higher compression.
Lol pull timing, I run microsquirt sans knock sensors. It's been a joy since I've lowered the compression back to 8.5-1. I tried tight squish, I got tired of changing head gaskets, the head got so thin the timing belt was getting loose. It'll turn over the 275/40/17' hankook rt615's no problem 3.35 1st gear T5/3.91 rear modded G80. B21F+t, B21 intake manifold.
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Old 06-07-2018, 11:01 PM   #41
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Lol pull timing, I run microsquirt sans knock sensors. It's been a joy since I've lowered the compression back to 8.5-1. I tried tight squish, I got tired of changing head gaskets, the head got so thin the timing belt was getting loose. It'll turn over the 275/40/17' hankook rt615's no problem 3.35 1st gear T5/3.91 rear modded G80. B21F+t, B21 intake manifold.
Just getting theoretical on your ass.
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Old 06-08-2018, 03:07 AM   #42
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No spacers on the small end, if they rods are crank steered.
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if the rods are crank steered, you don't need them (but they wouldn't hurt either).
Thanks guys, learning so much new stuff.

Emailed maxspeedingrods, and they are indeed to correct ones with a 23mm little end. They promptly gave me a little discount and free shipping, awesome. Put in the order and they should be here within about a week.

So excited, this engine is gonna be close to bulletproof . Well apart from the discussion that is the compression ratio of course , but hey, if need be, that can easily be fixed. At least the bottom end is solid.
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Old 06-08-2018, 04:30 AM   #43
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Don't need a machine shop to tell you if it needs bored, just buy a set of telescoping guages and measure the bore in the thrust direction and perpendicular. Check against specs and make the call.
Sure, but I could't easily get my hands on a decent bore gauge and he offered to measure it, so win win. Oh and also I wanted a pro to judge the ring ridge.
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Old 06-08-2018, 04:32 AM   #44
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Lol pull timing, I run microsquirt sans knock sensors. It's been a joy since I've lowered the compression back to 8.5-1. I tried tight squish, I got tired of changing head gaskets, the head got so thin the timing belt was getting loose. It'll turn over the 275/40/17' hankook rt615's no problem 3.35 1st gear T5/3.91 rear modded G80. B21F+t, B21 intake manifold.
Nice, good to hear, that's some serious rubber. That reminds me, need to check if my car is fitted with a G80, getting tired of those one wheel peels.
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Old 06-08-2018, 05:26 AM   #45
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Higher compression ratio does result in more thermodynamic efficiency, meaning more power out of boost. Doesn't mean your car wont run with lower compression. Higher compression will be more prone to knocking meaning without a proper ignition map for the compression your ECU may pull timing and negate the gains from higher compression.
Actually one of TB smart-er-er guys Janne aka Wagner posted some years ago some data that showed un-optimal ignition timing/curve costs more than lowering comp to some reasonable level...
the thing that hasn't seemed to penetrate here very widely is what the Honda and VW/Audi boys can get away with with their little 81-82mm bores and so many really nice motors like 3GSE, SR20DE and SR20DET, GMs XE 16v, E36 M3, and the latest Evo 10 and FJ Subie and a pile of French hot 2,0s with their "ideal" 86mm bore, 86mm stroke and pent-roof heads with that spark plug right in the middle,, is not saying that "we" with the relatively huge 92 and 96mm bores and a spark plug way over on one side, can do the same in terms of compression and boost...

I know a whole lot of experts sneer and say "I ran 9.8 and XX boost for years and I drove 110% every day and every shift..and never had any problems, so neener neener.."
Fine..
Everybody is always right..
Everybody's opinions are all exactly equal.

me though I'd prefer 8:1 and some fun boost and good ignition curve than be worrying about blowing rign lands out with no warning..
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Old 06-08-2018, 09:35 AM   #46
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This is true, everyone's opinions are equal. Which means yours is equally as worthless as mine
All the high compression stock engine GM guys would beg to differ on the CR discussion, as do many tuners.


So, if you're like John, and you don't know how to tune (or how/where to ask for help) by all means go low and slow. As they say, ignorance is bliss. If you don't know what you're missing, you'll never miss it. I don't see any honda comments. Your straw-man is weak and so are you old man!

Me personally, I tow the fast car with the 10:1 turbo car (that's a 96mm bore size x 8 for the kids at home, with 2v heads sitting on top. They're aluminum too). It's a new swap, I've only put 3 years on it and only had a few runaway boost situations. Hasn't been out yet (but soon. stupid lifters, stupid transmission. Stupid car that blows the tires off from an 80mph roll)


Anyway, Some of us actually do these things much to the chagrin of others, and a lot of us that do, have great success with it-again, much to the chagrin of others. Personally, I feel that low compression is a band-aid for ****ty engine management and ****ty tuning, and it comes at a cost. Perhaps just a transient cost, but a cost none the less. If you're running a system that isn't always repeatable in what it does (looking at you, LH), or one that's almost as old as John (looking at you, K-jet), then sure. You have little to no control except gross adjustments and prayer. Run low compression and be satisfied with mediocre results if that's the case.


What is "a fun amount of boost" anyway? That's a non-sequitur. Either the setup makes power or it doesn't, boost is just a number. Is 10psi boring boost and 20psi fun boost? On what turbo? What about 30psi? Is 15psi then just garden variety boost? Inquiring minds need to know


This is all meant somewhat tongue-in-cheek, like I said several posts up, your car, do whatever you want with it. If you really want to set john off on a tangent, start telling him that longer rods suck
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Old 06-08-2018, 12:05 PM   #47
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It might be easier and cheaper for the average turbobricker to get god results with compression ratios in the lower spectrum. A stock ancient 7.5:1 b21 longblock can easily give you 350whp with enough boost, timing and a few bolt-ons (90+ mani and na k-jet intakte) . Not the best powerband, but it works and is cheap ����
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Old 06-09-2018, 08:16 AM   #48
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I got plenty of experience in breaking piston ring lands over more than one setup, large turbo and NA :D

I would definitely agree that the tuning / timing mapping is the most important ingredient. What is optimal completely depends on the specific combination of hardware you have - turbo sizing, optimal boost range for that turbo, head flow, etc., etc. Much better to start with a more conservative timing map in your engine's peak torque range & then add carefully using logging or det can. I would have saved myself much headache & head gasket failures (in addtion to the broken pistons) if I had heeded that advice much earlier :D

Dropping compression makes off boost driving miserable.
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Old 06-09-2018, 02:13 PM   #49
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I got plenty of experience in breaking piston ring lands over more than one setup, large turbo and NA :D

I would definitely agree that the tuning / timing mapping is the most important ingredient. What is optimal completely depends on the specific combination of hardware you have - turbo sizing, optimal boost range for that turbo, head flow, etc., etc. Much better to start with a more conservative timing map in your engine's peak torque range & then add carefully using logging or det can. I would have saved myself much headache & head gasket failures (in addtion to the broken pistons) if I had heeded that advice much earlier :D

Dropping compression makes off boost driving miserable.
I thought reliability and longevity were maybe the most important..

And the last line "dropping compression"...Truthiness award contender ya got there>

8.0:1 on a B21 is raising compression.
And the all the yakitty yack about compression is more truthiness..
Compression ratio depends on when intake valve closes...everybody ought to know that, so talk of compression ratio without reference to intake valve closing is just flapdoodle..
And in the context of a turbo motor compression ratio must be looked at as a variable thing: it all depends on the volume of additional air that gets crammed into the engine.

So driveability on or off boost depends on cam timing and when the turbo begins cramming more volume of air in...

I've driven Redblocks with 8.0 and T cam and off boost they are fine..and when the turbo begins to spool at 2200 they drive more fine.

All this fapp-talk and nobody even mentioned what I consider the Number1 variable and that is hanging over everything: which fuel?

Whatever, carry on fapping..
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Old 06-09-2018, 07:36 PM   #50
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Mine is 8.5-1 I don't suffer any of those characteristics. Have you driven an 8.5-1 car to know what your talking about or just repeating what you've read on the all knowing internets?
I've heard more from an engine builder who has done race engines a couple of decades than read from the internet

I've had a reasonably powerful whiteblock with T6 pistons meaning 8.5 compression, and the same engine with Wiseco and 9.5 compression. There is a noticeable difference and 9.5 gave a sligthly better fuel economy too. Though it had only 700hp with T6 pistons and 800hp with Wiseco, both on E85.
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