I was wondering if anyone knows how easy it would be to bore and extend the stroke to increase HP and where to do it.. I have searched online, but haven't found much information on extending the stroke. Thanks for your help cause I want to try to keep the engine naturally aspirated for reliability.

-Blueorb

Aside from having a crankshaft custom made for you, i seriously doubt that you will be able to increase the stroke. The bore, on the other hand, can change. Mine is going from the stock 89mm up to 90mm, im leaving the head combustion chamber alone (aside from cleaning it up) and doing a mild port/polish, and going with 10.5:1 pistons. Basically, its a total engine rebuild, which is exactly what im doing. Any good machine shop can bore your block, but im not sure what the maximum bore you can get is. Going from 89mm to 90mm bore will change my displacement from 2389cc to 2443cc (techincally still a 2.4L hehe).

What you should look into before even thinking of this is starter stuff like intake, exhaust, header, cams, ECU, ect ect to get more NA. Im rebuilding because i have a blown front main and rear main seal (never good). So while i have it all in pieces, why not make it better?

I am rebuilding my KA also. i cant really see why you would want to incress the stroke as its already pretty long. you would be better with just incressing the CR, and porting the head. I am rebuilding with about a 9.5 CR, and forged bottem end, so i can go turbo later if i want to.

Thanks for the input. Yeah I have thought of doing port polishing and Boring it out and I know machine shops like CE racing does it and other places.. My friend told me make sure you don't go cheap unless you know them cause you get for what you pay for with the bore and port polish.

The reason I want to increase the stroke is because HP can be greatly increased by doing this upgrade. Example, BMW 325 to 330 have the same engine size, but the 330 has 20 more HP due to many factors but a major one is the stroke... this where I got the idea... it may be flawed, but it seems logical. If I am wrong please correct me.

Oh yeah to the guy that is rebuliding his engine.. there is a guy on this forum named dauntless he has a link (I think its his comp) but it is http://www.afterdark-tuning.com which he specializes in 240's and has a KA engine that has been tuned NA to 200HP like 2000g's so take a look... If you are going to bore it out. I would def look at boring it out more and getting forged pistions.. I saw a good site where a guy was doing it to his SOHC engine...... Good luck

Yeah, Daunttless is selling the DOHC NA with 200 HP. I am hoping to get 200 HP from a SOHC. And for under $1000 (im doing all the labor). I could have gone even more wild with 11.1:1 pistons and a complete head job to try and get 220 RWHP but i need my car to be a daily driver in a few months.

I know that there is a stroker kit for the SR20DET, but i believe its in the neighborhood of $2000. This does, however, change it to a SR22DET (now a 2.2L engine, instead of a 2.0L)

That is cool.. if I had a sr20det motor.. do you know where that kit was and the performance increase.... I do plan on getting the s15 motor.. so I want to know if it is worth getting..

Thanks

http://www.junauto.co.jp/produ...ml?en

JUN USA has it, dont know what it takes the power up to. But i guarentee its expensive!

The stroker kit is in the neighborhood of 6-8k from JUN/Tomei/Etc for the SR20. The maximum overbore on a KA is 91mm, but I wouldn't take it past 90, and a lot of KA Tuners persay feel the motor should be destroked for more power. : )

far be it from me to question the law, but how is destroking a KA gonna make more power? i know youd have less issues with balance on an underdrive pulley but really...

Im taking a wild stab at this, but i believe making the stroke shorter on a KA will allow it to get higher RPMs, therefor creating more HP, but losing a lot of low end torque.