My bone stock R may need a rebuild soon so I was wondering if the 11.1 compression will require tuning for it to run reliably and last for a long time?
There is no plans in the future for any mods but I would like to my options open if I decide to get some cams or what not. So the extra compression would help. But I am willing to install stock OEM O.S pistons if the JDM ones are too much work. This R is my daily driver so I need something that will run on 91 octane pee water without tuning.

 

If my horrible short-term memory serves me right, the USDM pistons are 10.6:1 and the JDM are 11.0:1 which resulted in a difference of only 5hp (on paper). I'm unsure about the head gasket thickness but I'm going to take a stab in the dark here and say that they are the same, across the board. I'm going to be an inexperienced dumb *** and say that: Yes you will be okay with out tuning. However, you should build the bottom end if your going to tear into it anyways. That makes sense to me, yah?

Whenever you do anything to your car, light or not, it's always a good idea to get it tuned. This will yeild knowledge to you which will help you decide the best mods for your car in the future and tell you what the current ones are doing. It will also tell you how your car is running, which I feel, is pretty vital.

 

The JDM pistons are 11.1:1 not 11.0, and i don(t think only 5 hp difference, because the EUDM model have 10hp difference and 11.1 pistons.

SAE hp is different to DIN or ISO hp

 

i would imagine it'd be ok because it comes with ITRs stock in japan and a few other lucky places. however, i see no need to upgrade if you don't plan on modding your car anyway. stock USDM is fine by me.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sylvain &raquo;</TD></TR><TR><TD CLASS="quote">The JDM pistons are 11.1:1 not 11.0, and i don(t think only 5 hp difference, because the EUDM model have 10hp difference and 11.1 pistons.

SAE hp is different to DIN or ISO hp</TD></TR></TABLE>
The more hp is from the JDM 4-1 Header and more agressive ecu tuning assuming you guys have the same setup as jdm 98 spec rs.

 

I recently put JDM ITR pistons in with my rebuild, and it runs fine and strong. It COULD use a tune, but it's definitely not necessary.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B2FiNiTY &raquo;</TD></TR><TR><TD CLASS="quote">
The more hp is from the JDM 4-1 Header and more agressive ecu tuning assuming you guys have the same setup as jdm 98 spec rs. </TD></TR></TABLE>

Yeah i'm with him on this one, the pistons count for as much as the ecu tunning to match them in JDM Land. So with a bit of tunning you should get more out of them...
good luck

 

i would swap to a jdm ecu (P73) before I tuned it cause it was cheaper. but if you dont want to do that just keep using the usdm ecu...it'll be fine. I would at least do one pull on it just to see were it stands.

 

The JDM Type R is not tuned to run on 91 octane, I believe it is 96 or higher, so running the jdm ecu on 91 with the pistons might give you some problems.

Victor Penner

 

The JDM ECU also conflicts with OBDII accessibility, I think, so you may have problems getting it through emissions.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PyR01-0347 &raquo;</TD></TR><TR><TD CLASS="quote">My bone stock R may need a rebuild soon so I was wondering if the 11.1 compression will require tuning for it to run reliably and last for a long time? </TD></TR></TABLE>

JDM ITR's run higher compression because they have access to higher octane gas. So, yes, you'd have to tune your car to take advantage of the compression.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dr Pooface &raquo;</TD></TR><TR><TD CLASS="quote">

JDM ITR's run higher compression because they have access to higher octane gas. So, yes, you'd have to tune your car to take advantage of the compression.</TD></TR></TABLE>

This is partially the case. Its not that they have access to higher octane gas, and we do not... its that not everyone across the US has access to the higher octane (93-94) gas (i.e. poor californians with the terminator ruling)....which I think is approximately the same rating gas they have over in japan...after the conversions, and all.

 

ive been running my 96 B18C spec R on 92 for year and a half with the p73 untuned and it ran like a champ, no knocking, no emssions problems, consistant spark plug wear, etc. Im not saying it wouldnt run better on 96 but, I had no apparent problems running on 92-93 octane.

 

Well the R is at the shop right now about to get it's head removed. Cylinder #3 has zero pressure when I did a compression test. So my uncle is going to check it out tommorrow and tell me if it is the rings or valves or maybe something even worse.