Hi so I am building my Gsr all motor and would like to know how much horsepower I should be making with my setup so if anyone could help.
-Bored over block to 81.25 with forged stock pistons
-Ported and polished head
-Supertech valves, retainers, and springs
-Ctr cams
-Skunk2 intake manifold and throttle body 70mm
-Tri-Y headers
-straight piped from 2.25 following 2.50 with burnout exhaust
-Aem ram air intake
I am planning on purchasing ctr or itr pistons as wellfor higher compression, so all that plus getting it tuned im hoping to make around 200 hp . How much do you think I will make?
And anything else you recommend adding?

 

With that setup you should be able to hit 200+ easily especially with a bump in compression. Really it will come down to tuning, but if your tuner is any good regardless of what software uses you should be able to meet your goal. I would open up the exhaust a bit though. At a minimum keep it 2.5" all the way from front to back. Also, you will know more after you get her on the dyno, but Tri-Y headers generally produce more midrange than raw top end power. If peak power up top is your goal, a header change may benefit you some as well as a larger exhaust. What tranny are you running by the way?

 

Thanks it helps a lot. And I have a 2000 Gsr hydro transmission with an act stage 2 street clutch and a 12 pound prolite flywheel, which feels amazing when shifting ha.

 

so whats the brand and specs on the pistons? Any headwork? are the valves just stock size replacements? also what ECU are you running? is it chipped? with a ITR map equivalent ecu you should be good for 190ish+WHP like that...if its just the GSR ecu maybe a touch less but still a strong sounding build.

 

He mentioned having it tuned so I was assuming a chipped ecu. Agree with above poster tho, easy 190s with a type R base map which is why I think a quality tuner could pull 200 out of it. And i was assuming they were just stock replacement forgings for a honed block rebuild. Just based on the .25 overbore it sounds like he took it down for rebuild and the walls needed a little honing so they rebuilt it basically stock but to accommodate the machine work. If they are higher than stock comp Pistons or have some type of burn or air fill advantage over stock castings then hitting his 200 will be all but guaranteed with a sufficient tune.

 

well i was also curious as to witch p72 pistons he had if usdm or jdm spec...slight variation in CR and depending if there was some deck milling done it could affect just how high the output ends up. also just fyi to poster stock pistons are cast not forged...forged implies high strength pistons

 

Yes im running a stock untuned ecu but my plans are to buy a p28 ecu and chip and tune it with Kaizen speed and I haven't bought the pistons yet but my goals are to buy the jdm itr pistons for a jump in compression.

 

Phearable.net is a very quality and affordable ecu tuning/engine management option as well. Good luck with the build!

 

ok heres my take -
some usdm itr replica pistons from say rsmachines will be fantastic and more than enough. avoid the ctr pistons.

use the oem valves if they are in good shape. the supertech 70lb springs are more than enough for ctr cams. you can use the rsx retainers they are cheap, reliable, and not a wear item like ti retainers.

2.5" exhaust with a big resonator and a vibrant muffler. if you are not careful setting the exhaust up you could very well have that asshat fartcan rasp.

i dont think i would run that on stock 240cc injectors. even jumping up to a prelude 290cc will likely get it done and not be at like 95% duty cycle

you may not hit 200whp depending on the dyno u go to, but 190 should be a walk in the park. even if you dont hit your number you will be very happy. that kind of setup will make great midrange and could be 135-140ftlbs from vtec to 7000 rpm which will feel fantastic. seems like the tradeoff between ctr and some stage 1 aftermarket cams. the ctr's make a bit less hp and fall off like 500 rpm sooner, but will give you an extra 5-10 ftlbs through the midrange which is worth it all day imo.
i had a pretty similar setup last year about the same compression, same cams, header, intake manifold etc as you are going to run and the thing was a blast. certainly faster than i though it was going to be