DCnotTHEshoes

What are <U>some of the way's </U>to get your compression to 13:1 for a type r motor ?

(both b16b and b18c, which are already at 10:8:1) ...?

- Thanx

ekim952522000

CTR pistons

Reid

None of the B18C's have a 10.8:1 compression ratio. North American ITR's have a 10.6:1 compression ratio, while ITR's in all other markets have a 11:1 compression ratio.

As has already been stated, CTR pistons are a cheap way to increase your compression.

JjuuN R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ixislikixi &raquo;</TD></TR><TR><TD CLASS="quote">
you can run pump gas. just tune it on 93 and throw some 110 octane in there once in a while just in case you run into some bad 93.</TD></TR></TABLE>
how the expletive are you supposed to know you have gotten bad 93? you bring a CSI kit to the pump and check it out before you pump it into your car?? get real...

ITR#132

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DCnotTHEshoes &raquo;</TD></TR><TR><TD CLASS="quote">What are <U>some of the way's </U>to get your compression to 13:1 for a type r motor ?

(both b16b and b18c, which are already at 10:8:1) ...?

- Thanx </TD></TR></TABLE>

Pistons, headgasket, mill the head, deck the block, weld the combustion chambers, ....etc. Anything that makes the combustion chamber smaller will raise the compression.

b18c-rDC2

my method was employing ctr pistons with a head milled 20k....if I were to do it again though Id probably run ctr pistons, leave the head alone and remove 1 or 2 layers from the head gasket....

cltitus

toda pistons will run it to 12.3 head gasket will run it up to 12.6 maybe 12.5 plus if you get headwork you can getsome 13 and up compression

Black R

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JUN.R &raquo;</TD></TR><TR><TD CLASS="quote">
how the expletive are you supposed to know you have gotten bad 93? you bring a CSI kit to the pump and check it out before you pump it into your car?? get real...</TD></TR></TABLE>


You'll know right away with all the pinging going on!

Bradstard

I wouldn't run 13:1 on pump gas. You can actually end up losing power if you have to retard the timing so much to compensate for detonation. Good luck with whatever your goal is.

92TypeR

13:1 is fine on 92 if you have cams that are big enough.

Example: Running ITR cams on a 12.4:1 motor is roughly the same dynamic compression as running Buddy Club 4's on a 13:1 motor.

92TypeR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by neo_ &raquo;</TD></TR><TR><TD CLASS="quote">13:1 + Pump Gas = Detonation


As Bradstard said, your timing would be retarded so much to compensate for it that its going to be a useless.</TD></TR></TABLE>

13:1 + Pump Gas + small cams = Detonation.

13:1 + Pump Gas + big cams = perfect

Let me make it more clear: On my 12.3:1 2.0L, the MAXIMUM ignition timing I can run on ITR cams is 18.5 degrees in the WOT columns, otherwise I get predetonation. With the BC5 cams, I am running 36 degrees timing in the WOT columns, and I can go higher, but the motor stops making power, I am no longer limited by detonation, but rather by power.

How much timing you can run is not dependent on your static compression, but rather your dynamic compression.

DCnotTHEshoes

Ok, thank you guys for the info. and help. I appreciate it.

-

itralex

I am running 13.1 on Pump 94 with m22x's

if i had to do it over again, would i go this high?........Nope, i would stick with something in the 12.0-12.5 area

b20mike

So detonation is a result of dynamic compression?? ie. a motor with the same static compression will yield less detonation with larger cams and thus less dynamic compression??

b20mike

I had a problem with detonation at load in the lower rev range would this be as greatly effected by dynamic compression as in the upper rev range??

camlob

Let me share this article that I just read. I am no expert and in fact a student. It explains pretty much dynamic compression in my opinion. But then again, the article could be wrong.

"At low rpm, there is little-to-no ramming of the cylinder from intake charge velocity. As the piston starts to move up the bore on the compression stroke prior to the intake closing, some of the induced air is pushed back into the intake manifold. This means the volumetric efficiency(breathing efficiency) and thus the effective displacement of the cylinder is well below 100 percent. In other words a 10:1, 700cc cylinder may only pull in 600cc of air. This means the dynamic CR, at 8.7:1, has dropped well below the static CR of 10:1. The bigger the cam, the more this effect comes into play. Lets consider what happens to the dynamic CR compared with the static when three cams, all in 108 LCA and 4 degrees advanced are installed. If this cylinder had a 12:1 static CR then the dynamic CR for a 300 degree cam would drop into the bottom of the 8s, the 275 cam into the mid 10s and the 250 profile cam into the mid to low 11s." It further states "to compensate (at least on cams to about 285-290 duration) and restore low speed output, the static CR must be increased."

On domed pistons: "The domed pistons may look like an easy short cut to more compression but it does not always deliver the hoped-for power increase. Although intended CR ratio may be achieved, the combustion process may be severely compromised by the presence of the dome."

Hope this helps and makes sense. I am also thinking of putting CTR pistons in my ITR.

b20mike

So if a had a small amout of detonation with my Crower stage 1 (essentially ITR) then with my BC4's there is a good chance that it will go away??

DCnotTHEshoes

ok.

-

sixspeeddemon

flat top valves and ctr piston will definetely bump up the compression on a type r