Thread: How far can you bore out an SR20DE?

Question #1
What is the maximum I can bore out a 1992 USDM SR20DE before I run the danger of cracking the block due to pressure? Keep in mind that I intend to go turbo with this puppy and run 25+ PSI (not soon, though.)

The reason I ask is because I am going to be purchasing a Brian Crower 91mm stroker kit, and since it comes with custom pistons, I am going to be boring it out a little bit at the same time to get the most bang for my buck. I was thinking of going to an 88mm bore, which would make it a little better than a 2.2 liter (2.213 liter).

I could also have them make the pistons high compression, but I'm thinking about sticking with 9.5:1 due to the turbo plans for later.

Question #2
Does anyone know what the piston volume, deck clearance volume, gasket volume (assuming stock head gasket), and combustion chamber volume is for these engines?

wouldn't it be smarter to go lower than 9.5:1 compression if you're going turbo setup??

i agree...

also, i believe the most the stock sleeves can be bored is 87mm. someone please correct me if i am wrong. beyond that you will need to have the block sleeved.

Well I know that Jun's old motor setup was about 9.5:1 on a built Bluebird and he was making over 500 WHP. He's currently running 9.5:1 on a 87mm stroke (making it a 2.1L) VE+T and making over 600. 9.5:1 on boost isn't necessarily BAD but it's higher. If I were running 25psi, I'd prolly only go 8.8-9:1 at most. But that is me trying to be more safe than sorry.

On another note, I wouldn't bore the motor out. It's a strong as hell motor the way it is and I've only really seen them stroked rather than bored. Besdies, getting a nice blalbearing snail along with that motor will more than make up for the power you'd get with a bore. My 2 cents though. Good luck man. keep us posted.

Thanks for the input, guys.

Actually another big reason why I wanted to get it bored out is so that I can use the next size up in piston rings - I'm concerned about cylinder wall wear and I don't want to have to go back in for a long time after I get done with this. So, perhaps I should just go to 86.5mm and call it a day?

However, if I did decide to bore it out for power, since I can't go further than 87 without sleeving it, I would just sleeve it and go to 89 (to make it a 2.26 liter). If I did that, what would you guys recommend for sleeve type?

Thanks,

What do you plan on using the car for?

If it is for drag racing I would just sleeve it and bore it to 90MM with a stock crank and call it a day. You can still rev the motor out to 9k or so and not worry.

If you are making a show/dyno queen just go as big as u can and drop a big ass turbo on it. I hope you aren't doing this.

Matt

startig out with a lready turbo motor that can handle a great deal of power, you really should choose what the motor is going to be used for, if its going to be a street car i would go with a slightly higer compression ratio piston with 86.5-87mm bore.

now if you are looking for sme mean power, i agree with the abvoe post go with sleeves,90mm bore,choice of compression pistons,huge turbo, and go with it.

these motors are really great as far as power to streetability wise ith stock bore

For the record, it's simple enough to make the above calculations if you know the total displacement and compression ratio:

Clearance Volume:

Vc = total volume/(4*compression ratio)


Swept Volume (stroke region):

Vd = (total volume/4) - Vc


Where by total volume I mean 2000cc, or w/e the exact number is. Also, the clearance volume includes the head gasket region. If you wanted them separate, it would be just a little extra work to calculate and subtract from clearance volume if you know gasket thickness and bore.

Well at this point I am looking to make it really, really fun for daily driving. I want to be thorough, and make as much power as I possibly can with this SR20 so I can drag race the hell out of it at the track once she's done. Torque is always fun, so maybe sleeving it with a 90mm bore and stroking it out would be the most "fun" way to go, and when I turbo it later it'll make more high end power.

So in this case deck clearance volume is going to be
1998/(4*9.5) = 52.579 (for stock)

As far as swept volume goes, is that going to be the same as piston volume? In this case it would be
(1998/4) - 52.579 = 446.921 (again, using stock numbers)

The swept volume accounts for the piston travel, and only has to do with the crank throw and bore, not piston height. It's the volume that the piston sweeps through as it moves from BDC to TDC (and vice versa), and the clearance is just the volume remaining in the combustion chamber when the piston is at TDC.