6G Celicas Forums

Ok, my understanding is that its really hard to bore a 5sfe because the cylinder walls are so thin. My understanding is that its not even worth it because its to easy to bore to much and weaken the cylinder walls so bad that it could cause cracking or stress fractures. Or that what you could bore out wouldnt make a big enough difference in the end.

Well me and a friend of mine where talking the other day about how i want to take my spare 5sfe and do the 5sfte upgrade. I was telling him that i wouldnt be able to run to much boost because the engine wouldnt be able to handle it. he said that i could bore it out and put sleeves down to make up for what was bored out and i would be able to handle higher compression and would be able to run higher boost. Now he is a Honda fan and has been working on cars since he was like 10 and has been building Hondas since he could drive. he really doesnt know a lot about Toyotas but he is a fantastic tech.

Can this be done? Has it been done? and what kinda of boost gain has come out of doing this kinda work?

This post has been edited by Havok1997GT: May 27, 2008 - 3:28 PM

Anyone? Or does no one know what im talking about?

I know what you're talking about but the bore is not the weak point for high boosting a 5S. You need to be looking more towards fuel/ignition control and monitoring if you plan to up the boost some.
That being said why are you looking for more boost than some of the guys on here are putting down on their stock motors? Pressure's been running more boost than me for a very long time on a stock motor with no hiccups so far. Hell, I'll go out on a limb and say he's been running reliably for longer than most 3S equipped swaps [quite a few on here are beside the point]. It's all in how you tune it and monitor it IMO.

BTW - I don't know how true that whole "you can't re-bore a 5S" BS is or not. It may be true [probably is considering a 5s block is just a bored/stroked 3s block - basically] that you can't "bore out" a 5S block - meaning you can't bore it out for increased displacement/gains but I've known plenty of people who have re-bored their blocks just for a fresh build. Alex is one of them. His bored block has been running strong for 5 years that I know of - no problems yet and that car has been abused. Knock on wood - sorry Alex.

This post has been edited by DEATH: May 27, 2008 - 3:46 PM

Im not really. I was think more along the lines of Stability. I was thinking that if i could reinforce the motor more then i would be able to run the boost more reliably.

But dont i need to replace the Fuel system and ignition system anyways? I thought all that had to be done just to boost at all. ( and i refuse to do anything half ass) which is really why im looking at making the thing as stable as possible.

Read my edit above BTW.

You have to remove some/most of the fuel system to boost yes: Injectors, Fuel pump. The ignition can be done without upgrades [in fact stock is best in some cases - OEM Plug Wires > Autozone Wires etc.].
That doesn't mean you shouldn't [IMO] upgrade to a MSD coil, NGK plugs etc. but gone are the days when we thought you had to run an MSD BTM or the like.

This post has been edited by DEATH: May 27, 2008 - 3:52 PM

so do you think Sleeves would be over kill?

This post has been edited by Havok1997GT: May 27, 2008 - 4:24 PM

Just not necessary IMO - but I'm not a 5S-FTE god or anything, nor is my knowledge in deep motor stuff. I'm sure others [*cough* Pressure2 *cough*] will be along to weigh in with their considerably more knowledgeable opinions in due time.

I'm really not sure about the sleeves deal. But I have had my engine bored out and I know of a few ohters on here who have done it. Mine is .03 over and strong as ever.


the whole piece about making it too brittle is just a myth IMO. You dont gain too much by doing it, but when i did my rebuild, I figured "what the hell"



as long as you dont go overboard, you shouldnt have an issue boring out your 5s. The weak point would be fuel and the rods.

Pretty much a x2 - worry about the fuel and ignition and just bore as much as you need to clean up the cylinder walls when rebuilding.

well, now i thought that if i bore it out, im going to have to get new Pistons because after the bore they will be to small. That another way to go about it was to sleeve after the bore and the old pistons will fit again. is this not true?

no its true. you will need new pistons, but they are the same price as regular pistons even if they are oversized. and its a great opportunity to upgrade (forged?) so you know you have a solid bottom end for what ever other overhauling you want to do.

Right but thats what i thought sleeving allowed you to do, reinforce without having to change out pistons.


Again, im not trying to half as anything with my project, but it would seem to me that that would be better. Bore all the imperfections out and sleeve and use the old pistons that are already built for the engine.

sounds like you have a solid plan. GL!


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