2.5 liter 250sx...just something i did...

[hafaznsensation]

Hey guys, new at the forum, but ummmm....i port polished & bored out my engine to a 2.5 liter engine and gained 35 horsepower. I will be sending pics of the dyno test later on. it cost me about $245 to do this, but it's all worth it. I just don't like the sound of 250sx, but its okay, more power for me. I will also KA-T this car (by the way, its a 93 240sx SE), but i am still looking around. The boostdesigns dude is pretty cool, and his kit is VERY affordable costing only @ $1900 for 220+ horses. hopefully ill get this thing running in the high 13's soon. Well thx for reading my first thread. I kinda like this place (feels like home haha...)

[GT500916]

how much did you bore you? i mean to go from 2.4 to 2.5 that sounds like a pretty big bore thats like what.. a 1.04% bore more over stock...

did you go like .40 or .60 over ?

i did a .40 over on my 67 stang with a 91 5.0 in it and thats as much as any engine should be bored because of the overheating probs, but i had to because my walls were worn out , and had to make them even.

and welcome home

[zauber]

i was always curious on displacement up modifications. because when i get my sr motor i wanted to look into increasing it's displacement. can one bore and overstroke, or are they similair?
like is bore increasing the radius of the cylinders, and overstroke changing the how far down the pistons compress?
sorry for asking a dumb question if it is one i just been curious on this for a while.

[pnoiSR20]

When boring out the block, are u still able to pass smog?

[SR20DETpower]

u pretty much got the grasp of it zauber

back on topic

nice gains, I myself believe the KA24de could go up to around 250rwhp and still be streetable on NA power... should be enough to put you in the low 13's with traction mods... I know someone who ran a 12.9 with a 250rwhp KA. Be good enough to beat up on a lot of mustangs and older camaros

imagine upping the compression, running the new pdm billet NA II cams, fabricating ITB's, and doing all the bolt ons like pulley, flywheel, H/E.... that would be enough to put you over 200rwhp I believe


to bad you didn't dyno the car with just the boring done, would like to see what gains that provides by itself, likewise with the porting...

[GT500916]

Originally Posted by pnoiSR20

When boring out the block, are u still able to pass smog?

when you bore i dont think it changes anything as far as smog regulations, you just gain some 5-10 hp if that, depending on ho wmuch you bore... wich i dont recommed if you want to gain some HP...

if you are getting a turbo or something and replacing the pistons might as well get .20 over pistons and bore the block exactly for those pistons , so they will fit nice and tight... dont ever bore block .20 over then buy pistons that are .20 over because sometimes that .20 over can be a .21 or.19 so its better off to buy pistons and meassure then exactly what they are and do the bore...

Originally Posted by zauber

i was always curious on displacement up modifications. because when i get my sr motor i wanted to look into increasing it's displacement. can one bore and overstroke, or are they similair?
like is bore increasing the radius of the cylinders, and overstroke changing the how far down the pistons compress?
sorry for asking a dumb question if it is one i just been curious on this for a while.

yes bore is just making the cylinders slightly bigger and overstroke is making the strokes longer. IMO stroker kits are not good with turbos because of the longer strokes it will make the crank and rods and pistons work harder with the turbo and will put a lot of stress on your engine... so with the SR just upgrading the turbo is the best way to go, unless u just go with a stroker kit and no turbo, or stroker kit and run low boost will be good too, i dont think they have stroker kits for the SRs? i might be wrong...

If your SR has a lot of miles on it and you plan on rebuilding it do the bore .20 over, thats the most common pistons size, if you go .40 or .60 then you will have major overheating problems specially with a turbo and the SR already having overheating problems with lots of people i heard about.

As an example.. i bored my mustangs block out because it needed it... it was a 302ci 5.0 engine and it needed a bore so i went .40 over and now i have a 306ci engine... there is no power gain from bores, just makes the walls of the cylinders all nice and new and straight...

[SR20DETpower]

it ups your displacement, thereby allowing more energy to be made


they make a few stroker kits for the SR20det

really though they are kind fo pointless, they do work the engine harder and don't really provide that much power for the money, your better off with turbo upgrades, or you shouldn't have bought a small ass 2 liter in the first place....

2 liter < 5.7 liter muhAhahaha no matter how you cut it, the engine just has more capability to make power

[D-Bo]

sr20det, which V8 would you put in a 240?

[Chuki_breath]

an old school hemi lol that would be sweet lol. Come rumbling up to the races....id be like ricer what?? ricer who???? yea bring out daddy's viper. bitch.

[D-Bo]

where can you get them?

[Chuki_breath]

my uncle knows where to get them, but there a hefty penny to get. Plus it would probably tear our little 240's in half when you mash the gas. You would need alot of reinforcement.

[sidewayzS13]

yea sr20 stroker kits are crazy expensive though like 6 grand if i had everything i wanted done to my engine and i had 6 grand lying around id spend it on the stroker kit but it would be like the last engine mod if ever do

[SR20DETpower]

I would either go with a chevy z28 302cu in motor with a m-21 4 speed if you wanted a carb'd setup

or a LT-1


LT-1 has good fuel injection system and can be had in pre obd-II years unlike a ls-1. You can find them with a t-56 transmission as well.

[hafaznsensation]

Originally Posted by GT500916

how much did you bore you? i mean to go from 2.4 to 2.5 that sounds like a pretty big bore thats like what.. a 1.04% bore more over stock...

did you go like .40 or .60 over ?

i did a .40 over on my 67 stang with a 91 5.0 in it and thats as much as any engine should be bored because of the overheating probs, but i had to because my walls were worn out , and had to make them even.

and welcome home

I went .40 over, but i forgot to mention i also got upgraded vavle springs and some better cam gears. ^_^; One question, can I still get a turbo kit with my motor now since its been bored out? I mean...its not that much bigger...then again...maybe it is. Could you guys give me some feed back on this one? Btw...thx for the posts.

P.S. Also, check out the turbo kit from boostdesigns and tell me what you think. "Good for the price" or "Dude..thats crap". Thx

[nissanfanatic]

Generally you get whatever percentage increase in displacement as an increase in power. Soooo

2389 stock cc.
2500 bored 2.5l

You should get a 4.6% increase in power. That should have given you 162bhp. It depends on your P&P job but average is about 15-20whp scenes how the KA head flows pretty well to begin with. I would believe your numbers, but where the fuck did you get all that shit done for $245? Pistons alone are about $400 at the cheapest. a P&P job usually runs about $600 if you take it to someone you can trust. Machine work usually runs about $150-$200 if you half-ass it and don't get it hot-tanked, rotating assembly balance, O-Ring, decked, and the crank micropolished among other things I am forgetting. Oh and not to mention you have to know what kind of sketch pattern to put on the cylinder walls. Pics would really put my skepticism at bay.

And I would never stroke out an SR. Just not the engine to do that. The 350 is the kind of engine you stroke out. Torque ownz jooo.

And I can not see stroke affecting how well a turbocharger works. If it is sized correctly, then the engine configuration should not matter. The engine is flowing a set amount of air. Remember, people have put turbochargers on just about everything now. From SBC& I beleive BBC to freaking Hayabusas(yea watch the video! 18psi on that mofo!).