CTR PISTON COMPRESSION RATIO

[speedminded]

i have a ITR full swap....and a ls long block w/ ctr pistons rebuilt...and a gsr tranny....and a new job, LOL!!

Mmm, full itr swap...where did you run across that?

[Jdm94Coupe]

well u know what they say..........










everythings on ebay! lol...... nah totaled itr a minute ago, lol....

[Jdm94Coupe]

btw i just looked at ur cardomain.... do ur calipers RED, lol....

[speedminded]

btw i just looked at ur cardomain.... do ur calipers RED, lol....

if i had charcoal wheels i would, dunno how red and bronze would look together.

[Jdm94Coupe]

o damn ur wheels look charcoal in the pic in your sig, i thought you re did them, lol nvm

[Jdm94Coupe]

btw wut do u run in the 1/4.... ur car runs quick (watched the video)

[speedminded]

btw wut do u run in the 1/4.... ur car runs quick (watched the video)

dunno, never ran with the LSD...was spinning 2nd and 3rd gear before.

[Jdm94Coupe]

oh ok ok

[BLk92DA]

btw wut do u run in the 1/4.... ur car runs quick (watched the video)

[Jdm94Coupe]

wutz so funny?^^^ somethin u need to say to me?

[silversol]

nevermind

[y-49]

i was gonna order some oem ctr pistons for my ls/vtec im building but i want to run pump gas. so not a good ideal. what kind of compression would i have with a ls with b16 head? im glad i read this before i started waisting money. lmk thanks

[Vteckidd]

The b16 head is listed with CTR pistons an LS block.

your BEST BET is to run PR3 pistons, itll be a much better engine. trust me

[AllmotorDC4]

I was wondering, would it be safe to use itr pistons on a Ls? With a built Ls head?

[RISKYB]

thanks for the info mke

[k20]

ls block with gsr head and ctr piston ...is it safe

[Thundercat]

ls block with gsr head and ctr piston ...is it safe

P72 head/B18A/B Block

STD = 13.170743903246784
.25 OS = 13.236528215133324

You like Pump Gas ???

[mr.koupe]

here you go for all your b series compression calculation needs.... rep me plz

http://www.clubcivicquebec.com/compr...r_bserie_f.php

[Mangrum]

if you are trying to build a na gsr like i am wanting to in the future.. why would you not want to go with the ctr pistons if they have a higher compression? than the pr3 pistons? dont you want to gain the highest compression possible?

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

[Vteckidd]

if you are trying to build a na gsr like i am wanting to in the future.. why would you not want to go with the ctr pistons if they have a higher compression? than the pr3 pistons? dont you want to gain the highest compression possible?

no you dont want the highest compression possible. You want the highest compression with the flattest dome for an even flame front.


Optimizing combustion chamber space is often one of the most over looked aspects of an engine build. Although its a simple concept it has many rewards, including increased power, lower octane requirements, reduced fuel consumption and better overall throttle response. This is really important when your build has a compression increase as one of its modifications. Raising the compression ratio is equally important as the quality of the combustion space.



If your combustion space isn't well defined you wont see the full potential of the compression increase. Also your fuel octane requirement will be higher with a poorly defined combustion space.

The pent roof Honda 4 valve combustion chamber is one of the most efficient combustion chamber shapes, basically a triangle, with a flat piston. As the dome of the piston is increased the space becomes oddly shaped and not only takes longer to burn the air fuel mixture but also requires more ignition timing (starting the burn sooner) to do so. The reason it requires more timing is because the area becomes more like a winding passage vs an open triangle. This in turn promotes detonation and increases the octane requirement. As you can see in the diagrams below the large dome will cause the combusting air fuel mixture to hit the piston at 45 degree angles in some areas diluting and diverting the combustion energy. In the other diagram you can see the engine with the flat piston has a clearly defined area and combustion gasses will push directly on the piston downwards providing a more efficient piston push. The better defined combustion area requires less timing because of its superior burn efficiency.

Many things affect compression ratios. Here is a list of things that change compression with all other things being equal.

-Stroke length will change compression ratios, longer strokes increase compression while shorter strokes decrease compression.

-Bore size will change compression ratios. Bigger bores increase compression ratios while smaller bores decrease compression ratios.

-Head gasket thickness will also change compression ratios. Thicker head gaskets decrease the compression ratio and thinner head gaskets increase the compression ratio.

-Piston dome volume changes compression ratios. larger domes increase smaller domes decrease compression.

-Piston compression height (the distance from the center line of the wrist pin to the flat of the piston) {measured as if the piston was a flat top}. This can determine how much the piston is in the hole or out of the hole or flush with the block. the more the piston is in the hole (under the block deck) the less compression, the higher it is the more compression.

-Chamber volume changes compression ratios. The larger the volume the more it decreases the compression. The smaller the volume the more it increases the compression ratio.

-Spark plug depth also has a small effect on compression ratios. By taking off the sealing ring or washer you can add a small amount of compression to any engine.

In short anything that changes or can change the volume of the cylinder or combustion space will change the compression ratio. Even a valve job can sink the valves into the head slightly and increase chamber volume thus decreasing compression slightly.

When planning a built engine always try to increase the compression without adding to the piston dome. Here are some examples of ways to increase the compression without adding to the piston dome (keeping the flattest possible piston).

With so many areas affecting compression ratios its almost never needed to use dome volume to gain compression, although it is the easiest way. Certainly not the most efficient.

-flat faced valves can add .2-.4 on many engines
-milling the head can add upto a full point (be sure to account for piston to valve clearance changes).
-over boring can add .1+
-stroking can add quite a bit depending on how much you add to the stroke.
-decking the block to change the piston from negative deck height to flush or slightly/less negative.

When you buy pistons the advertised compression ratio is for one engine combination. For example if you buy 12:1 pistons for a 2.0 liter rsx engine and plan to put them in a 2.4 liter tsx enigne you will have a lot more than 12:1 compression.

[Mangrum]

wow you really went into detail.. thank you that helps alot

[southside]

what about b16 pistons in a ls with ls head

[Samhonda95]

Not to go againts anyone but I had a stock ls bottom end with a type-r head (cams,intake,tb, etc.) and built a ls bottom end with .20 ctr's and swapped it out. Needless to say, it runs very well.

[TheChosenOne]

What he said.

All that stuff about CTR pistons being the devil is uneducated lies. I had a ls/vtec with CTR pistons and it ran like a slave on the underground railroad: Fast and with a purpose!

All that really matter is build quality. Think about it. If they really were that troublesome, than Honda would have never made them.

[Vteckidd]

Uneducated lies?

nah its proof

Just because you got lucky doesnt mean everyone else will.

CTR Pistons were designed for short stroke CTR engines.

not 89mm stroke LSVTECs.

Honda never inteneded those pistons to go into other combos of engines.

Uneducated? this info has been around before you even were on IA or had a honda to mod.

Me an johnzm found this info out like 5 years ago when i was building my OEM 190whp GSR. He built a GSR with CTR pistons, and he had nothing but problems, he had to pull 10 degrees out just to avoid detonation.

ANyone that has TUNED or DYNOED a CTR pistons powered GSR or ITR or LSVTEC KNOWS that its a problem.

Anyone that knows a LSVTEC with GSR Head and CTR pistons knows that the engine WILL BLOW UP because the CTR pistons stick out of the hole and will hit the head. eventually a rod bearing will get pounded out.

So no, its not lies, its backed up by the likes of

Omniman- Inventor of LSVTEC
DonF- Engine builder 40 years
Jim Justice- #1 engine machinist in USA

and many others.

[southside]

what about b16 pistons in a ls with ls head

Since no one seen it the first time.

[Vteckidd]

thats fine

[southside]

what should the compression ratio be?

[Josh miller]

my gsr hatchback was like half a car i thought gsr post to beat h22 whats faster

[Jazze Ek]

What would you say to a gsr with ctr pistons and flat face valves and head ported

[Vteckidd]

What would you say to a gsr with ctr pistons and flat face valves and head ported

it will blow up, compression will be around 13+:1

Run ITR or PR3 Pistons

[Jazze Ek]

Have already put the setup in and have not had anything 2 go wrong with the motor and it pulls really good. Could this be something that could go wrong later on

[Vteckidd]

like i said, you are on 13:1 compression, you WILL detonate . Get it tuned

[Boosting EG]

Question,

GSR block , 40 over ctr piston , gsr rods and crank and a B16 head is that safe and what power are we talking about or would you go with , GSR block , LS rods and crank , CTR pistons a B16 head ?

[Vteckidd]

Question,

GSR block , 40 over ctr piston , gsr rods and crank and a B16 head is that safe and what power are we talking about or would you go with , GSR block , LS rods and crank , CTR pistons a B16 head ?

YOu are reading the thread right?

I dont advocate CTR pistons in ANY MOTOR unless its a pure B16 (1.6 Block and head)

Any of the setups you listed will be well over 12.7-13.3:1 compression which is way too high for the street.

you will be better off using B16 Pistons, flat top is a much more efficient piston

[Boosting EG]

thanks

[Jazze Ek]

it will be tuned soon but can i get by with a vtec controller and i also have a 97 itr ecu

[Vteckidd]

no you cannot, youll need to go to OBD1 an have it tuned with Crome or Hondata.

[southside]

no you cannot, youll need to go to OBD1 an have it tuned with Crome or Hondata.

How much is crome vs hondata?

[scttydb411]

How much is crome vs hondata?

crome is the cost of chipping an ecu...approx $80.
hondata is the cost of the unit plus chipping/installing to ecu=$280-700 depending on model installed.
tuning is the same for either one.