That's the stuff I was talking about. There are perks to using stock Honda blocks when all parts are already forged. Unlike the H22 where the pistons are still cast and an obvious weakness for boost our motors are "fully built" out of the box as far as I'm concerned.

To me the F20C is already low on torque for the first 4000rpm NA. With an added charger in the line and lower compression it would surely be very noticeable. Low compression is for the V8s imo then you get no tradeoffs.

Now that said, I think Ap2 pistons in the Ap1 would be tits for reducing compression and still use all OEM parts. It might even leak less given the better ring design on the AP2. With some titanium retainers it would complete the list for "building" the block. Everything else is gold from factory.

It will be interesting to see if your built block will be better. I hope you run the same gear/tune so we can compare.

 

For tunning go to Bisi

 

Someone somewhere in the FI section had a dyno sheet of a N/A motor running at 9:1 and 11:1 difference was small like 15hp. No biggy IMO but I guess everyone's different. My butt dyno barely detects 15hp changes, ambient affect cars that much.

The piston swap is an interesting point, not sure actually how the 2.2 was made from the 2.0 but we know it was stroked, still I'm not sure what the piston changes were, yet I think that drop would be too much..... maybe not.

Gear = same for a while, but there's no way the tune will be. It was 11.1:1 prior and I'll build for 9:1 (though 8.5 is prime turbo CR) because I want the motor to be spirited off boost. I think any comparison would be apples and oranges as a built motor is always going to demand a tuning change unless you specifically set out to keep it the same.

My first goals out of the 700hp cap motor will be the max of the 30R, from there I'll go 3" down pipe with a butterfly valve or simply run no exhaust at all still debating. Then injectors, map sensor, intake piping etc. to get out of the 500 range IF I so choose to, a 35R or more likely ...larger and the motor will sing at 9k instead of 8500 current.

 

Well they shaved the pistons a pit to cope with the longer stroke. That's precisely why you would get a lower compression using ap2 pistons in ap1. Ap1 pistons can be shaved too but I'd go oem again. The drop would be around 10.3 or so if I remember correctly.

For overall Hp I'm sure dropping compression is not a big deal but torque at low rpm will most definitely suffer. You will also get full boost later in the band. In 100 degree weather with the A/C on I am positive the low end will suck a bit. If you are using AP2 bottom end keep it at 8.5k rpms. Any higher and you are running record high piston speeds. I saw one of these vids where DK blew a 2.2 at 9k, it was more like a duh moment haha.

 

^ Good info on the pistons, hadn't ever researched changes, I just figured I have what I have.

What I meant was they tested it N/A without the turbo setup yet. The hp drops were pretty small across the board from what I expected. I was thinking 50hp or something major...it wasn't. I'll search around for the dyno chart.

If the 4k hp change from 11.1:1 to 9:1 is say 10hp, that's really no biggy to me but I suppose it's certainly something to consider.

On the flip side going from 11:1 up to 13:1 doesn't net a whole lot of hp either really. Couple points didn't seem to do as much as expected in either direction.

I know the piston speed in the 2.2 is probably getting crazy past 8.5k That's why I left it at 8.5 thus far but fully built I expect those rods to work their butts off. ALSO on boost numerous tuners have told me the boost helps to take the load off by providing positive pressure to the piston for turn around instead of it having to be returned by the rod.

I'm amazed he blew at 9k though.... do you know what blew? I've personally been in the car at a 10,500 rev in a 2.2 that survived it fine. Log showed the mechanical over-rev... scary.

Also though.... I won't be running it into 9k, it'll be track only time that I actually run to 8500k and 9k will be my over-rev zone to avoid a shift in a corner that barrrrely needs it, probably be partial throttle then too. Otherwise I'll set it to 8500 and generally shift at 8 even on a fun canyon.

Hell as is.... I find most 30R/35R s2ks don't really need to be above 6k on canyons, I have trouble even putting more down then that on the horribly paved gravel flooded roads we carve, more about tire selections then hp most days.

 

[QUOTE=05TurboS2k,Jul 16 2010, 02:08 PM] ^ Good info on the pistons, hadn't ever researched changes, I just figured I have what I have.

What I meant was they tested it N/A without the turbo setup yet.

 

"fire fire fire"