need some suggestions on comporession ratio for my pistons..

B16, B18, B20
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need some suggestions on comporession ratio for my pistons..

By 1-low-92-EG-Sedan
- Mon Feb 04, 2013 6:03 am #325545 ok so im getting just over $1,100 for tax returns....so im going to buy my pistons and rods and get the block machine work done and what ever i have left over will go to my trans that is sitting at the shop...

but i have some questions and hopefully some one could help me out here..im thinking of going with wiseco 11.8:1 - 12.4:1 with a bore size of 81.5
is this safe to run with a rebuilt stock LS head?? or should i do a step down and get 11.1:1 - 11.6:1 with a bore size of 81.5???

and how do i go about tuning the car?? i have a stock obd1 P75 ecu...do i need to buy a chip or can it be tuned as is??

any insight or criticism is welcome..it is my first performance build and want it done right..any help is welcome...thanks in advance

By HeikDiesel
- Mon Feb 04, 2013 2:00 pm #325558 You'd get more performance out of a vtec head than you would high compression pistons. You might look into that as well. All depends on what you want to end up with.
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By Fada Blayne
- Mon Feb 04, 2013 5:34 pm #325578 instead of doing a build i honestly suggest that you just buy a vtec swap and work ur way up from there :thumb:
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By 1-low-92-EG-Sedan
- Mon Feb 04, 2013 10:32 pm #325601 well i have the ls head done and it was machined, milled, and had a 3 angle valve job...and i already have the block sitting waiting to be machined as soon as i decide what do do for internals... but i plan on doing a vtec head later next year when i have the money so im trying to do the block work now and get it out of the way so when time comes the block should be reliable to handle the vtec head

thoughts?? :?

By bks84
- Mon Feb 04, 2013 11:32 pm #325603 theres nothing wrong with putting high compression pistons in an LS motor with the intent of swapping a VTEC head on at a later time.

You can not swap in pistons that are 3:1 to 4:1 higher in compression (stock LS is 9.2:1...) and run on a stock ECU. It will have to be tuned. You will at the very least need to chip the ECU, crome or something similar if youre cheap, Hondata or Neptune if you've got a lil extra money.

What are you end goals, once you go with a VTEC head swap?

If its just going to be a fun engine, take a serious look into a set of RS Machine pistons, you can achieve close to the CR you've suggested, for lot less than going with a Forged piston, and you dont need to use Forged rods either, which would save more cash for future upgrades.

If it were my build, I'd do a simply RS machine PR3 piston, on stock LS rods w/ARP rod bolts installed, have it all machined and balanced.

Heres a link to some pistons, I would use
http://www.ebay.com/itm/RS-MACHINES-B16 ... 23279ef7e2
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By 1-low-92-EG-Sedan
- Tue Feb 05, 2013 3:46 am #325607
bks84 wrote:theres nothing wrong with putting high compression pistons in an LS motor with the intent of swapping a VTEC head on at a later time.

You can not swap in pistons that are 3:1 to 4:1 higher in compression (stock LS is 9.2:1...) and run on a stock ECU. It will have to be tuned. You will at the very least need to chip the ECU, crome or something similar if youre cheap, Hondata or Neptune if you've got a lil extra money.

What are you end goals, once you go with a VTEC head swap?

If its just going to be a fun engine, take a serious look into a set of RS Machine pistons, you can achieve close to the CR you've suggested, for lot less than going with a Forged piston, and you dont need to use Forged rods either, which would save more cash for future upgrades.

If it were my build, I'd do a simply RS machine PR3 piston, on stock LS rods w/ARP rod bolts installed, have it all machined and balanced.

Heres a link to some pistons, I would use
http://www.ebay.com/itm/RS-MACHINES-B16 ... 23279ef7e2



i know i will need to get a tune..but i just dont know how any of that works..i understand mechanics..but im not so great with computers and such :lol: ...so now i know i will definitely need a chip or just get a hondata or something of the sort...any suggestions on what kind of chip i should get?? like i said..im not so great with computers/ECUs

the reason i am going with forged piston and rods is mostly for piece of mind i guess...i know they are new and never beaten on and by the time i spend the money on getting the arp rod bolts and some of the machine work done to make them fit properly..i would just rather spend that extra money and get forged rods with the arp bolts already installed

i greatly appreciate your feed back...sorry if some of the questions i ask are noob...but its my first performance build and i want it done right the first time considering the amount of money going in to this build

By bigpunn421
- Tue Feb 12, 2013 7:35 pm #326315 sell the ls head you have. no matter how much work yo do to it it will never out flow a stock vtec head.


my buddy built a all motor b20 with 11.5to1 no vtec with cams and he made less than 160whp with a tune.

im not saying yours will be slow just saying that the non vtec head flow like garbage.

ls vtec or vtec motor i would say too. japan star in albany sells new jdm gsr motors for $1800 with warranty




also forged internals at that power level reduces power. your rotating assembly will weigh more with the stronger forged internals. that means slower revs and less hp.

i know of people using ls internals on a vtec motor. thats a great setup. people push the ls internals to over 300whp.

the weakest part of ls rod is the rod bolts. arp makes them better

i would suggest ls internals in a gsr motor for more hp. for the most part the vtec head makes about 30-40hp more than the ls on the same motor.
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