What is the furthest our blocks can be bored out to?.

[silver bullit]

What is the furthest our blocks can be bored out to?. I know i have heard 10-20-30-40-50-60 over but how much is to much?
I know there is meat on the block but i dont wanna take it to far where is compromises the blocks structural integrity, cant have the cylinder walls to thin next to the water jackets.

Not to mention its useless on a closed deck block to have to sleeve it.

 

[TunaTalon]

The maximum bore recommended by Magnus is 88mm.
Magnus Motorsports - DSM/Mitsu Engines

2.4L 6 bolt block, utilizing the largest bore possible (88mm) this is the largest displacement on 88mm stroke we can safely achieve.

See http://www.dsmtuners.com/forums/str...acement-various-combinations-bore-stroke.html for the effect on displacement for various combinations of bore and stroke.

 

[Big Woo]

88mm = a 3.465 inch bore diameter, but as stated above this is the spec for the 2.4 liter block, not the 2.0 block.

 

[silver bullit]

Well what is the limit threshold without going to sleeves, on the 2.0-2.1-2.2-2.3-2.4 blocks, skip any information except max bore size, and stroke.

 

[project_tsi]

Well what is the limit threshold without going to sleeves, on the 2.0-2.1-2.2-2.3-2.4 blocks, skip any information except max bore size, and stroke.

I'm not positive but form what I remember .060 over was the largest on-the-shelf piston available.


However, if you are regarding your own block, take it to a machine shop and have them measure the current bore. Also ask them their recommendations for boring. You always want to bore the least amount possible. So if you can run .020 oversize, do it and don't bore it to the max for more displacement, as you won't notice any difference.

 

[silver bullit]

Whats the max recommended compression, i see 9 to 1 but i was thinking of doing 10 2 1

 

[RipperXX]

If you go 10:1 I hope you are using propane or water/meth injection because you are going to have one hell of a hard time tuning. I personally would not go over 8.8:1 but hey thats me.

 

[project_tsi]

The lower the CR you run equals a larger tuning window you will have. On my 2.3L with 8.8:1 CR I ran 31 psi daily on 93 and meth. On the 2.0 I am building I am going with 8.3:1.

 

[silver bullit]

The lower the CR you run equals a larger tuning window you will have. On my 2.3L with 8.8:1 CR I ran 31 psi daily on 93 and meth. On the 2.0 I am building I am going with 8.3:1.

I know but you know as well as i do that a 9.0-9.5/10.0 compression motor will allow same hp numbers on lower boost then the 7.8/8.0-8.3-8.5 on more boost, just the tunning window will be more difficult and knock becomes more of a issue. Not to mention how much faster (Maybe 100-800 rpm @ max boost sooner thanks to the bump in displacement similar to a stroker (2.1-2.2-2.3-2.4 etc) would spool) a turbo will spool on 9.0-10.0 compression then a 7.8/8.0 etc would.

I plan on using 93+ maybe 94 since its in my area and race gas on higher boost but i definitely want to run a 9.0 compression piston.

I think for for the sake of getting a decent setup going while keeping the car semi street able with 9.0 compression pistons and maybe 30 over though i like to bore it out to the max.

I dont need to bore the block as it is fine but would a 10-20-30-40 maybe a 50/60 over bore, would that in turn help help bump the volumetric efficiency (V.E.)?

 

[GVR4592]

Higher compression won't spool the turbo any quicker, in most cases it's actually a slower spool. The increase in torque might make it seem like it's coming on quicker, but it's not.

 

[project_tsi]

i like to bore it out to the max.

Did you even read any of my previous posts'? While boring will give you a hair larger VE, you won't gain anything. Like I stated before, you should always bore to the smallest size you can get away with, that way if you have a failure and need to, you could bore the block again so it can be reused, and not leaving having to find a block. Also the larger you go, the thinner the cylinder walls get, leaving you more prone to cracks, overheating, etc.



9:1 CR is perfectly fine IMO for a pump gas car. My setup was closer to 9:1 than the listed 8.8:1 b/c my head and block have both been cut down. I ran 31 psi daily on a 35R sized turbo with pisss gas 93 and meth injection. Without the meth it could see low 20's psi on a decent tune.

You also have to remember that boost makes more power than CR. Boost also makes more power then timing. So, Boost over Timing over CR. I would rather have an engine that spools 100rpm slower but allows me to run 3more psi, rather than an engine that spools 100rpm faster but is unable to run the extra 3psi on the same octane.

 

[silver bullit]

What is the stock bore?

I measured mine with a micrometer and i got 3.338

 

[GVR4592]

Stock bore is 3.346. You have an inside micrometer that fits in the cylinder?

 

[silver bullit]

Stock bore is 3.346. You have an inside micrometer that fits in the cylinder?

Yeah i do but i think its off a few thousandths.

Never mind the 3.338, i got the better one out and i got 3.3462

 

[awesome_asim187]

Another question regarding the wall. What is the thickness of the walls between the pistons and the water jackets?

 

[SBR Joe]

If you go 10:1 I hope you are using propane or water/meth injection because you are going to have one hell of a hard time tuning. I personally would not go over 8.8:1 but hey thats me.

I tuned a 10:1 car, 93 octane and 23 psi on a e316g....no problems, no meth injection. And correct me if i am wrong i think i have seen .080 over. Wiseco and Ross make .060 over though.



joe

 

[brute]

pisss gas 93 and meth injection

Highest I got is 91.

To the OP, why exactly do you want the largest bore and higher compression ratio? As stated previously, larger bore doesn't really net you any gains while weakening the structural integrity of the block. And compression ratio is for those ultra-race cars when the owner/driver is trying to squeeze out every last horsepower.

project_tsi's got it going on -- boost over timing. Compression ratio (in my book) doesn't even play a factor for power. It plays a huge role when tuning, but not for power.

And if you want larger displacement, instead of going with a .060 or - heaven forbid - and .080 over bore, why not just step up to a stroker?

Also, as a side note, compression ratio does not help boost. GVR4592 has had a vigorous time trying to defend this statement. There's a big thread about it, which I'll find for you if you want. For what it's worth, a dream street motor for me would be low compression stroker with huge boost. But that's just me.