Hey guys I was wondering is it possible to bore out an is250 (2.5L) to a 350 (3.5)

 

Is it because of compression ratios or what?

 

It's possible, but not easily done due to the aluminum block and the required sleeve work that would need to be done. In addition, getting to 3.5 with just bore would be tough, you would likely need to bore and stroke it (similar to what Toyota did to get the 3.5L in the 2GR).

Better to just start with a 2GR block.

Jeff

 

I didn't read too much into why he was asking. Could be curiosity, could be genuine interest in doing it, could be many things.

For what it's worth, if you just used IS350 pistons in a 4GR, you would get 3.2L.

Jeff

 

You're right, this isn't a typical task, and I would also say that Toyota's sleeves in their aluminum blocks are much thinner than even you are thinking. If any boring was to happen, it would 100% require new sleeves, and they wouldn't be done the same way that Lexus did their sleeves (which are fused to the aluminum block and have a rough spiny surface between them for better adhesion).

I definitely agree that it would be better to start with the larger engine, that said, if you were going to do something like Ray Hall did with their 2GR and bore it out to 96mm, re-sleeve it and use a modified 1GR crank, custom pistons and reworked 1UZ rods to get to 4.0L, you could probably start with either a 2GR or 4GR block and the work would be essentially the same, haha. You would probably still want to find a set of 2GR heads though, so again, probably best to just get the 2GR engine and start with that.





Jeff

 

Well im asking out of curiosity and out of doing it. I was wondering if such a thing is even possible since i know how to do alot of work myself but not much when it comes down the the insides of the block and so it is possible to by 350 pistons amd just swap them into my 250?


My main goal is to add power without getting a new car. I was gift my 09 is250 in mint codition but it lacks power. Iv read alot of articles from this site on superchargers anx they seem like a waste of money for only boosting you up to 50 more whp. . I want the car over 300 maybe up too 400 but inbetween there would be perfect. Iv also been thinking turbo bit i know the compression ratio is 12:1 and that wouldnt really work with most turbos 52mm and up i assume?

 

If that is your goal, my suggestion is probably honestly to sell the car and find an IS350. This isn't a simple task, both to do mechanically or to control electronically. If you really want to keep your car, look into a 3GR-FSE engine swap with stock electronics, or just do a complete 2GR-FSE swap (engine, electronics, all of it).

Turbo or supercharger would be more possible these days with tuning available.

Jeff

 

I will read these replies whether they benifit me or not or whether i like them or not. I got a lot of good info even asking on here. Even though some of these answers are beyond me. Im still very new to modifying any major engine componants. My most advance skils would have to be, knowing how to change spark plugs, headers, cams, and the radiator.



Im here to gain knowledge from experienced people who admire the Is models.

 

Dude, sell your 250
Buy IS-F
Bam!!! 416-hp instantly, even more than you asked for.
Enjoy driving your new car the same day.
Save yourself thousands of dollars and multitude of headaches.

You can thank me for it later, lol