I have a Version 6 sti engine and which is apart awaiting some forged pistons. I am in 2 minds whether to go ahead with the 2.0L engine or change it for the USDM 2.5L sti Block. (I am leaning toward the 2.5 ATM)

My question is "is it possible?"

What compatability issues are there?

Will I need to change the cams in the version 6 engine?

Sorry if these are DUMB :o questions but I am relatively new to the engine building game?

Thanks in advance.

SOO00B

Yes it will work just fine. The only thing you may need to worry about is the Compression Ratio with your heads and the 2.5L STi block. You may have to run a thicker headgasket in order to keep the CR low, or if you dont mind a higher CR you can just run stock headgaskets.

I would suggest conversing with Ron @ Axis Power Racing to find out what the CR would be with that combo.

-Matt

I'd rather run a higher compression then mess with the timeing diffrences that come with a thicker head gasket. For some reason I remember some builder telling me that a thicker gasket can set of the timeing 2 degrees or so from the left bank to the right bank. Maybe its hear-say. Though.

If I were you though and had the block apart, I would look to help the topend and get some cams. A 264 cam or a 272 if your willing to sacerfice some of the idle. Since your going to be gaining a lot more bottom end, cams would help keep the topend from getting choked up with the extra exhaust from the .5L more displacement.

Just my 2¢. Good luck with the buildup.
-Neal

What flavor Ver 6 STi engine do you have?? plain or type R/RA

Why did you pull the stock forged pistons? They are just as good if not better then aftermarkets. The STi 2.0 and 2.5 lower ends will handle about the same HP in stock form. What are you looking for a high RPM screamer or a lower rpm engine with slightly more torque? What trans? The STi gearing is too short for a 2.5l block.

What flavor Ver 6 STi engine do you have?? plain or type R/RA

I believe it is plain


Why did you pull the stock forged pistons? They are just as good if not better then aftermarkets. My mechanic suggested that I change them as a saftey measure


The STi 2.0 and 2.5 lower ends will handle about the same HP in stock form. What are you looking for a high RPM screamer or a lower rpm engine with slightly more torque? I plan to track race the car every now and again, But I plan to drive it around on the street so torque is certainly a priority

What trans? The STi gearing is too short for a 2.5l block. STI 6 speed with DCCD

If I were you though and had the block apart, I would look to help the topend and get some cams. A 264 cam or a 272 if your willing to sacerfice some of the idle. Since your going to be gaining a lot more bottom end, cams would help keep the topend from getting choked up with the extra exhaust from the .5L more displacement.

-Neal

This is interesting, The whole reason I wnet with the version 6 engine in the first place was that I was told by more than person that the ver 6 heads and cams were the most effecient/power friendly of all the STi engines to date. I will need to look into this further.

SOO00B

The STi 2.5l will be well suited with the STi 6spd and work well for your application.


The Type R/RA STi had agressive cams, but I dont know about the standard STi. Either way the Ver 6 heads are nice units and more then capable of making the power you are looking for.

The STi 2.5l will be well suited with the STi 6spd and work well for your application.


The Type R/RA STi had agressive cams, but I dont know about the standard STi. Either way the Ver 6 heads are nice units and more then capable of making the power you are looking for.

I was hoping to make around 320 WHP. This setup should cope alright with that?