mrsteezy123

The machine shop came across a isssue with my block, so my gsr block had "pr4 .8" stamped ls pistons, so I felt that those were OEM spec b18a1 pistons. I​​​​ ordered 81.5mm weiscos assuming it was stock bore, but the machine shop tells me the pistons fit right in.

​​my first question was if we can get away with just a hone and he stated that the piston to wall clearance would be out of spec, because the cylinders aren't perfectly in round.
luckily he has some 82mm flat tops but I'm a little shook about running these on stock sleeves.

The machine shop said they have a couple people running around with stock sleeve b20s making north of 400 which raises my confidence.
But if I search the forums It seems many people recite that it's a bad idea, but how many people actually tried it?

Anyway the build would look like this currently
b18c1 block
Eagle rods
Arp hardware for everything
Weisco flat top 82mm
Ls crank
Gsr head.
he said he can send it to get css and that will make it much stronger with that bore, but also said if I only plan on making 400 I don't necessarily need it.

Keep in mind I'm running 93 pump no e85 for me, so any fresh opinions on this subject would be appreciated

Chance EG

I'd say the OEM sleeves start to become a bit questionable regardless of any other factor at the 400WHP level. Obviously a good tune can help longevity significantly.

Assuming the flat top pistons would give you about 10:1, if the P2W clearances are fine then this won't impact the reliability of your engine. If the sleeves are a questionable component, 10:1 pistons aren't going to hurt anything more.

Personally though if you're dead set on 400WHP I'd take the extra time and money and get it bored out to 81.5mm to get the cylinders back to perfect round, and getting the CSS process done if you intend to stack up miles on this engine.

mrsteezy123

The bore is already at 81.5 and is out of spec a hone won't do it, the piston to wall clearance is already too loose, 82mm pistons or virgin block is my only choice.
The tune will definitely be on point, I'm just real concerned about cracking a sleeve even thiugh 400 is not that crazy, I plan on Daily driving the car once it's done.
and I think compression will be a tad bit higher due to the ls crank, and the head getting resurfaced

Chance EG

Get the CSS process done then, so you don't have to second guess yourself or hold your breath every time you rev out a gear.

Make sure of the compression ratio you'll end up getting. If you're doing something like GSR pistons in an LS or vice versa, that will have a drastic impact on the resulting compression.

TheShodan

iTrader: (14)

Sorry. I disagree. The CSS process isn't even remotely necessary at 400whp on a B18c block. A lot of us have been at that for years before it was even needed. 500whp, she, if you want CSS , that's more for that level. But 400whp, I wouldn't think twice and run the stock sleeve with a 10.0:1 piston on an LS crank..

extremeracer

Since you'll be on stock sleeves you want to avoid detonation and excessive cylinder pressures at all costs. It is therefore important your turbo size and more importantly, the flow rate can support the horsepower target without pushing the turbo to its limit flow (which will require race gas or E85) . Trying to squeeze 400whp out of a GT28 on 93 Octane might be difficult and beyond the octane limit of the fuel where as 400whp on a GT3076 (50 lb/min minimum) or similar might be more achievable.

Balor_Gr

Thats our findings here too.
b16 stock gt35 at 400 hp 5 years+
b16s with gt28s, small t3s or t3/4, exploded before 300-400, cracked sleeves etc.
Its in my opinion how much you push on the low rpm than hp. Probably combination of too much torque on long duration combustions.
My tuner (very experienced on hondas) said stock sleeve is tottaly different than sleeved on the mapping.
If i were you id still do the CSS for the 82mm just for the peace of mind. Because if it bothers your brain now it WILL bother you every time on wot.

2x0

Going an extra 0.5mm over should not hurt anything for that power level on stock sleeves. Run conservative timing, make sure the turbo is within it's efficient range to keep IAT's down and you will be fine. From what I've seen the sleeves work perfectly fine at 400whp unless you are going up to 84mm bore, then it gets iffy.

mrsteezy123

It's a sc61 I made 309 with 10lbs and ls pistons.
should be perfect for 400
Yea a part of me wants to get css because I know they warranty the sleeves for anything under 500hp and that's a huge peace of mind.
​​​​​​​But than again we got experienced guys like shodan and my machinist saying that 400 is cake

mrsteezy123

Its a ls crank and rods so the compression will be bumped up slightly nothing crazy though, and yes css is cheap and I'm definitely considering it, time is my concern sending it out to css means another two weeks off this build and I wanted this car back on the road by the end of the month, which is definitely possible if I skip the whole css process
​​​​​​​Even with a 82mm bore? That raises my confidence, I go back and forth every 20 mins, one things for sure the car won't see much over 400 ever, but it will be daily driven

mrsteezy123

Is a 84mm bore even possible on a b18 with stock sleeves?
I think the service limit is 82mm which is why I'm a little paranoid

TheShodan

iTrader: (14)

We know the limit on stock sleeve is 82mm, and again, whether you are 81.5mm or 82mm, the piston to wall clearance and assemly must be right. So there is no point in trying paranoid because it could fail either way, if not put together properly.

You cannot bore to 84mm on a stock sleeve

mrsteezy123

Yeah it's the only reason 82mm is even in consideration is that my bore is currently out of spec and a virgin gsr block is similar price to css, but I don't want to do neither tbh.
​​​​​​
i was reading on older threads on this subject and golden eagle said "looking to run boost with 82mm sleeves is asking for trouble" that's a pretty reputable company, so the opinions are conflicting.

I might have to go css just for the peace of mind even though it might be overkill

TheShodan

iTrader: (14)

Peace of mind is nothing to dismiss. But CSS CNC WERX only guarantees 81.5 mm for their process anyway.

mrsteezy123

FML I did not know that..
​​​​​well Idk what to do then in that case, I guess just get everything perfectly in spec and just go for it on stock sleeves, with just a bore and deck.
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