quick question

[kasperferio]

wat up ctvtec.. im building a allmotor gsr stock 81mm sleeves have a full built head all skunk2 valve train pro 1 cams... wat compression ratio would be good thnking bout jdm itr pistons and rods, or eagle rods with 11.5-1 comppression.. thanx

[DOHCtor Miguel]

wat up ctvtec.. im building a allmotor gsr stock 81mm sleeves have a full built head all skunk2 valve train pro 1 cams... wat compression ratio would be good thnking bout jdm itr pistons and rods, or eagle rods with 11.5-1 comppression.. thanx

11.5:1 is good or 12:1. What HP goals are you trying to make?

[STITCH]

11.5 is alright, I think 93 octane maxes out at around 13:1 compression. You'll also want to clay the motor for valve clearance.


Higher compression isn't going to significantly raise your peak power, most likely will increase midrange if tuned properly.

[Herminshs]

11.5 is alright, I think 93 octane maxes out at around 13:1 compression. You'll also want to clay the motor for valve clearance.


Higher compression isn't going to significantly raise your peak power, most likely will increase midrange if tuned properly.

Is more like 12.5:1 with a good tune.

[STITCH]

Is more like 12.5:1 with a good tune.

I've seen people with 12.5 max out at 91 octane.

[Mr Layy]

oh man... not that im stealignt he thread. but im going with practically the same build. i dont know what im doing for the head right now, but the block is done, with a .25 bore usdm itr pistons on stock rods and crank in a b18c block... what should i do for my head?

[RLA_DC2]

please make the subject title a little more specific next time

[kasperferio]

sorry bout the title i noe for next time.. as for horsepwer goals i want somewhere in between 185-200 whp.. dont really knoe if its possible with 81 mm bore. i just want a fast reliable dd. but i dont wanna go to crazy for now have another build im interseted in starting after this one

[kasperferio]

im gonna tune with hondata s300, i have
block:
eagle rods
kinkg bearings
itr oil pump+water pump
arp rod bolts
vibrant belt tensioner
greddy timimg belt

head:
skunk2 pro valve train
skunk2 flat valves
mild p&p
skunk2 pro 1 cams+gears
bronze valve guides
arp head bolts

[daveedd357]

12.5:1 compression ratio will compliment the cams that you are going to use . anything less and you will suffer in the lower rpm range. You should always design your bottom end around the cams that you are going to use. The smaller the cam the lower the compression. Big cams tend to bleed off compression at lower rpm, requiring more compression to maintain good Transient Response. Under-camming an engine will require better fuel because the cylinder pressure will be too much for pump gas, depending on the compression chosen.

[kasperferio]

good to knoe, now where im i gonna get a tuner so i wont blow it up..... with 12.5-1 comp with good tune how much whp will i be lookin at (estimate)

[myrakle]

with that comp u should get bigger cams maybe pro2s, good header and a nice tune should be over 200hp

[daveedd357]

At this point, head flow is going to determine the peak hp. only the dyno can tell how much ultimate power will be reached. good headers and a 2.5inch exhaust can never hurt, as they will help in midrange response.

[kasperferio]

already have 2.5 inch exhaust doing sohc turbo i a few weeks. stock motors. headers i will definatlly get. my concern is that i dont wanna have any problems with reliabilty. already have pro ones so i dont really wanna get rid of them.

[daveedd357]

it is the builder for reliability and the tuner for drivability/fuel economy