• CTR PISTON COMPRESSION RATIO

      This article was originally published in forum thread: CTR PISTON COMPRESSION RATIO started by Vteckidd View original post
      Comments 89 Comments
      1. IntegraXTR's Avatar
        IntegraXTR -
        12.9 on a gsr motor? damn thats high, is that safe for daily driven because I was going to ctr pistons or itr.
      1. Vteckidd's Avatar
        Vteckidd -
        12.5 is the threshhold of PUMP GAS.

        I will go into more detail of why CTR pistons are not ideal at a later time (prob tomrrow). i would go with PR3 pistons, they yield highercompression that a ITR pistons and they are cheaper.
      1. IntegraXTR's Avatar
        IntegraXTR -
        Quote Originally Posted by vteckidd View Post
        12.5 is the threshhold of PUMP GAS.

        I will go into more detail of why CTR pistons are not ideal at a later time (prob tomrrow). i would go with PR3 pistons, they yield highercompression that a ITR pistons and they are cheaper.
        which one gets a better power gain?
      1. Vteckidd's Avatar
        Vteckidd -
        ill draw a graph tonight and post it tomrrow.

        IMO PR3 pistons will make more power than CTR pistons and ITR pistons. In an all motor car you want a even flame front with as little turbulence as possible. You dont want to split it, and that causes the motor to scavenge, and volumetric efficiency drops, making the motor less productive and efficient, power decreases. in a nutshell, ill draw graphs to explain this later tonight
      1. IntegraXTR's Avatar
        IntegraXTR -
        so I should just go with pr3 pistons? thats the first time I ever had someone tell me to go with b16 pistons in my motor, everyone is always like get ITRs or CTRs.
      1. Vteckidd's Avatar
        Vteckidd -
        As promised here is my graph. THESE ARE NOT TO SCALE, but a good enough representation.



        This graph (LEFT) depicts a PR3 piston. Notice the much flatter dome. what this does is when air is coming down the intake manifold, and is let into the combustion chamber, it has a more direct shot across the piston to the exhaust. There is less turbulence, IE air trying to push back off the dome of the piston , the air flows more freely, etc. Also, the FLAME FRONT which is the explosion that happens when the air and fuel meet in the combustion chamber is ignited by the spark plug. the "explosion" is distributed evenly across the top of the piston.

        The Next Graph(RIGHT) is a CTR piston. the higher dome DOES give you higher compression. that is true. However, look at the AIR TRAVEL on this graph vs the PR3 piston. there is MUCH more turbulence. Also notice how the Flame Front is split in two, that means less effciency.

        Volumetric Effciency is essentially how well the motor runs. Most honda motors run above 100% VE if built right. You cannot make more power without more air, and the air must flow freely. A motor will run longer and last longer and be more efficient with proper air travel and combustion effciency.
      1. IntegraXTR's Avatar
        IntegraXTR -
        so my question now is, should I go ahead and switch to PR3 pistons or just rebuild with gsr pistons? keep in mind that its going in a gsr motor.
      1. Vteckidd's Avatar
        Vteckidd -
        PR3 pistons if you are staying all motor.

        PR3 Pistons will yield around 11.6:1 in a GSR motor
        ITR pistons will yield around 11.0:1 in a GSR motor
        CTR pistons will yield around 12.9:1 in a GSR motor
      1. IntegraXTR's Avatar
        IntegraXTR -
        thanks, I'm just looking for the best power gain while staying all motor in a budget, any ideas on where to get new pr3 pistons with rings?
      1. Vteckidd's Avatar
        Vteckidd -
        Topline they are on Fulton Industrial

        or

        Honda
      1. TallGuy's Avatar
        TallGuy -
        Would you recommend ctr pistons for the b16a1?
      1. 99SI's Avatar
        99SI -
        That's not a graph, it's an illustration! lol. Sorry, I had to do it. I'm impressed by your "graphing" skillz Mike, I didn't know you were such an artist! lmao!
      1. IntegraXTR's Avatar
        IntegraXTR -
        Quote Originally Posted by TallGuy View Post
        Would you recommend ctr pistons for the b16a1?
        I would just because I've seen a b16a with ctr's run before.
      1. Vteckidd's Avatar
        Vteckidd -
        CTRs in a B16 arent bad. They are significantly lower compression than the other 1.8l.
      1. Jdm94Coupe's Avatar
        Jdm94Coupe -
        .....yea i sounded stupid 2 years ago......
      1. Vteckidd's Avatar
        Vteckidd -
        it WILL blow up.

        you cannot run CTR pistons in an LS block with a GSR head. the combustion chamber of a GSR head is too small, the piston dome on the CTR piston will hit the head. eventually itll pound the rod bearings out and rip the wrist pin out of the piston.

        get a b16 head, r get rid of those pistons. compression will be very high, look at the 1st page of this thread. its around 13:1

        P72 head/B18A/B Block

        STD = 13.170743903246784
        .25 OS = 13.236528215133324
      1. Jdm94Coupe's Avatar
        Jdm94Coupe -
        yea i seen that, and stover told me it's not good to be over 12.5 or somethin like that.....well b16 head it is....it wont hurt anything to run itr cams will it?

        would a ctr head be ideal, since ctr heads are obviously meant to be used with ctr pistons? cause i wanna run either itr or ctr cams anyway..
      1. Vteckidd's Avatar
        Vteckidd -
        The heads are pretty much the same. i wouldnt but a CTR head cause you can buy b16 head and buy ITR cams for MUCH cheaper.

        Even with a B16 head youll be at 12.8ish compression. still high, i suggest you get a cometic headgasket that is thicker to bring the compression down
      1. Jdm94Coupe's Avatar
        Jdm94Coupe -
        ok thankz....pm me if u find a b16 head for a good price....thankz
      1. IntegraXTR's Avatar
        IntegraXTR -
        Quote Originally Posted by Jdm94Coupe View Post
        ok thankz....pm me if u find a b16 head for a good price....thankz
        think someone is selling one in car parts forum
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