bore size

[lbkid180sx]

i was wondering how big of a bore i can go on my sr20 without sleeves beeing needed and how much of a compression ratio can i go with im looking to get cp pistions

[Sileighty_85]

Its pointless, once you max bore the cylinders you cannot properly rebuild the engine after that, unless you sleeve the block.

Just go with a set of 86.5 at a 9.0:1

[Dream240]

I'm curious, what usually causes the cylinder to taper after usage? Poor maintenance? Too much boost?

Also, if you were to overbore a block to 89.5mm, and you needed to do another rebuild 10 years and 150K miles later, what are the chances that the cylinders will need to be overbored again? CAN you even overbore again? Couldn't you just get the block serviced without increasing the bore size?

Just some thoughts....

[codyace]

i was wondering how big of a bore i can go on my sr20 without sleeves beeing needed and how much of a compression ratio can i go with im looking to get cp pistions

What are your goals?

.5 overbore is all you really need. Stick with 8.5:1 or 9:1 compression. Anything beyond that bore wise really is race/track specific.

[codyace]

Also, if you were to overbore a block to 89.5mm, and you needed to do another rebuild 10 years and 150K miles later, what are the chances that the cylinders will need to be overbored again? CAN you even overbore again? Couldn't you just get the block serviced without increasing the bore size?

Hard to say really. You should always check bores before a rebuild. At a minimum you can sometimes get away with a quick brush hone and be on your way.

[cotbu]

Sleeve are recommended for 40 over, 87mm pistons, IIRC
I'm curious, what usually causes the cylinder to taper after usage? Poor maintenance? Too much boost?
straight travel, fresh honed (O), Out of round, taper (o ) It's the nature of the beast, the internal combustion engine.
Even normal driving has the same effect, just more time less wear. I'm not saying things can't speed this up drastically, like overheating, improper piston ring install, etc.
Knowing this they give us tolerances, and The almighty sleeves, I think there an 86mm sleeve kit for the SR.

[lbkid180sx]

im looking to make a good amount of power but not really sure how well the block handles bore i didnt want to go to big but not stock bc im pulling the motor apart might as well go a little bigger bore and comp but if stock bore is fine and will make a good amount of power then ill stay at 86mm and just go 9.0:1 comp ratio ..... i do eventually want to go with sleeves but thats for my other block.. im kinda new to the sr20 so im not sure of its limits

[codyace]

im looking to make a good amount of power but not really sure how well the block handles bore i didnt want to go to big but not stock bc im pulling the motor apart might as well go a little bigger bore and comp but if stock bore is fine and will make a good amount of power then ill stay at 86mm and just go 9.0:1 comp ratio ..... i do eventually want to go with sleeves but thats for my other block.. im kinda new to the sr20 so im not sure of its limits

What are you power goals



Seriously, if everyone on here is looking at 400 whp, than stock bore (or .5 over) with stock compression is your best bet. will you see marginal response increases at 9:1 compression? Surely....but it's not worth the detonation risk if you ask me on a street car using varied fuel sources.

[lbkid180sx]

right now car is stock im going with a aem computer with wideband and map sensor full race turbo kit gt35r tomei head parts hks fuel rail not sure what size injectors yet so im looking for like 550whp with eagle rods cp pistons .... if this much power needs sleeves then i guess thats what it cost to go fast im sure theres some stuff i left..... i kno the 35 can make alot more then that but i dont want to get a 30r then want more power and have to buy another turbo and if i can make more then that with out needing sleeves i will 550 was my "safe" number"

[codyace]

right now car is stock im going with a aem computer with wideband and map sensor full race turbo kit gt35r tomei head parts hks fuel rail not sure what size injectors yet so im looking for like 550whp with eagle rods cp pistons .... if this much power needs sleeves then i guess thats what it cost to go fast im sure theres some stuff i left..... i kno the 35 can make alot more then that but i dont want to get a 30r then want more power and have to buy another turbo and if i can make more then that with out needing sleeves i will 550 was my "safe" number"

I'd be more concerned with the Eagle Rods than the factory sleeves at this point

Sounds like you'll be making some good power though, regardless. I'd say you're fine on a stock or .5 overbore yet.

[lbkid180sx]

concerned witht the eagle rods as in a problem with them ?

[shagspeed]

Order Stock Z32 TT pistons from JE or CP ... Run them... There extremely strong and 87mm. Run a torque plate when boring... Everyone I know in the SR20 crowd ran this setup including me... I been building / working on SR20's for about 14 years now... This combo has never let me or anyone I know down...

BTW I ran 500WHP on 87mm bore for over 100K miles most of that was at 403WHP on Pump gas daily driven.. I ran Crower Rods that where double tanged for both the 53J 17mm rod bearings and the 54C 19mm wide bearings.. I ran the 19mm wide bearings with Arias Z32 TT pistons. Arias where using High Silicone in there Aluminum back in the day not sure if they still are the idea was that the High Silicone where less brittle but not as strong... Kind of like Mild steal vs. Chrome-Alloy.. Arias would not knock as bad when cold and where better for long life... Like I said this was the idea. Mine still knocked when cold and I always let my engine idle and warm up.. Like I said mine lasted over 100K and failed to overheating on a failed thermostat and not anything to do with the build itself...

Just my 2c Good luck with your build hope all works out...

Chris Allen aka Shaggy
500WHP 54C SR20DET in B14 back in 2001
Current Project is 52F/1N5 head in S13 W/GT35R on Haltech 475-500WHP on Pump Gas is the goal.

[brian3676]

Order Stock Z32 TT pistons from JE or CP ... Run them... There extremely strong and 87mm. Run a torque plate when boring... Everyone I know in the SR20 crowd ran this setup including me... I been building / working on SR20's for about 14 years now... This combo has never let me or anyone I know down...

BTW I ran 500WHP on 87mm bore for over 100K miles most of that was at 403WHP on Pump gas daily driven.. I ran Crower Rods that where double tanged for both the 53J 17mm rod bearings and the 54C 19mm wide bearings.. I ran the 19mm wide bearings with Arias Z32 TT pistons. Arias where using High Silicone in there Aluminum back in the day not sure if they still are the idea was that the High Silicone where less brittle but not as strong... Kind of like Mild steal vs. Chrome-Alloy.. Arias would not knock as bad when cold and where better for long life... Like I said this was the idea. Mine still knocked when cold and I always let my engine idle and warm up.. Like I said mine lasted over 100K and failed to overheating on a failed thermostat and not anything to do with the build itself...

Just my 2c Good luck with your build hope all works out...

Chris Allen aka Shaggy
500WHP 54C SR20DET in B14 back in 2001
Current Project is 52F/1N5 head in S13 W/GT35R on Haltech 475-500WHP on Pump Gas is the goal.


so i assume by 19mm bearing you did the gtir bearing mod. Was it worth it in your opinion?