Hello, I have a 2001 ITR and I’m looking to gain more torque out of the motor. After much research I have decided to re-sleeve and bore as opposed to stroking because the car is used as a daily driver. I have rebuilt the top end with Skunk2 Stage 2 cams as well as valves, springs, retainers, etc. The intake, throttle, intake manifold and exhaust have also been upgraded and Hondata has been used for the tuning. I have a few questions with regards to the bottom end being upgraded and any input to point me in the right direction would be much appreciated. First of all I have heard varying opinions about the maximum “safe” bore diameter of a sleeved block. My plan is to bore to a diameter of 85mm to bring the displacement up to a 2.0 litre. Is this diameter attainable safely with a high compression motor? My second question is in regards to the pistons themselves. I would like to install JE pistons with a compression ratio of 11.5:1 but I have read that boring causes a decrease in compression. This is a concern to me because the S2S2 cams work well with high compression. Would it be necessary to go with a piston of higher compression, say 12:1? My third question is in regards to the Rods. I would like to replace the factory rods with Eagle rods. Are Eagle rods heavier that the factory rods? If so, would this affect performance? My fourth question has to do with where the block meets the head. Because the cylinders will be of larger diameter would it be a good idea to bore the portion where the valves are located in the head to 85mm as well? I’m not sure what this area is called so it’s hard to describe what I’m referring to. My next question has to do with gasoline injector sizes. Currently mine are stock, but after rebuilding the bottom end in addition to what has already been done to the motor would it be necessary to increase the size of the injectors? Lastly, because of the high compression, what level of Octane gasoline should be used? Is there a general rule when it comes to motor compression versus Octane level? Sorry for the list of questions, but any and all help would be greatly appreciated. Thank you.

 

cliffs?

 

Like thats a lot of questions...

Current state of mind

maybe someone else could help

 

This may not be in the order you wrote, but here goes:
A) If you're planning on boreing the block to 85mm there are a few other factors than what you mentioned that will be associated with the reliability of the motor(stroke being one of them). New sleeves will be a must if boring that much on a B18C. My .02, I would go with Weisco or Arias pistons over JE as well.

B) It will really depend on who puts your engine together, but your 11.5:1 pistons may not be a bad idea. It is true the larger lobed cams (Jun3, Toda C, Skunk2 2, etc..) love higher compression, but IMO, I would be willing to bet you probably won't see more than 65,000 miles go on the engine till you're looking at a rebuild (probably just opened the flame war gates with that comment). This may be fine for you but if you're looking for an engine to go 100,000+ miles (without any "major" problems), I would sacrifice a little power and use a smaller compression.

C) 310cc injectors may do the job, but I would probably go with 370cc and maybe even a little bigger. I can't imagine you would tap the 370s out though.

D) Don't know the weight of stock ITR rods (could search for it on here but I'm too lazy), but aftermarket rods would be a must for this build. I personally like Pauter and Crower rods, but I haven't personally heard any complaints about Eagles.

E) If you're serious about spending this kind of money on your engine, port matching the head to the block will be worth every penny.

F) Not sure where you live, but you will have to buy the highest octane possible in your area. If you live on the West coast you will have to deal with crappy 91 octane in which case adding octane booster would definitely not be a bad idea.

Anyway, there is my lecture. A lot of it is personal opinion and I'm sure there is several things people will disagree with me about, but overall with a build like that I wouldn't be surprised at all to see you put down 250 whp with around 150+ lbs. of torque with some good tuning. Just keep in mind, even though it will be fun you pay to play

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bbasso &raquo;</TD></TR><TR><TD CLASS="quote">Like thats a lot of questions...

Current state of mind

maybe someone else could help </TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rand0m &raquo;</TD></TR><TR><TD CLASS="quote">cliffs? </TD></TR></TABLE>

Would probably feel the same way, but I'm stuck at work and getting paid right now to read this

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phred &raquo;</TD></TR><TR><TD CLASS="quote">I have read that boring causes a decrease in compression</TD></TR></TABLE>

Well...I'm not 100% on this answer but I'll give it a shot...from what I understand...when you increase displacement relatively you will decrease compression due to the fact that you now have a higher power/torque output motor with the same pistons...obviously youre not gonna make the same amount of hp and torque...so you must increase ur compression to accomidate the increase in displacement...i dunno if u got that...i kinda juss went along with what i was thinking...but heres an example...the Honda s2000 originally came with a 2.0 liter motor producting 240 hp...in 2004 they came out with a 2.2 liter motor also producting 240 hp...if you read in this site... http://www.s2000.com ...it says something like...they had to up the compression a bit to make the same HP...

i dunno if that helps but thats all i got

 

Return.
Enter.
Ascii Code 32.

these are nicknames for the key on your keyboard that is apparently broken.

 

Dude, First of all obviously when u increase piston diameter, compression falls due to incresed overall cc size\ piston head surface area.

due to increased piston size you will have a higher inertiatic force being exerted on your small end and consequently your bottom end.

You will require the extra weight in the eagle rods due to a two+ fold increse in the mass of your larger pistons at 8000- 9000 rpm.

INfact your increase in cc \piston surface area means a TOTAL ENGINE REBUILD to Maintain
Anywhere near factory RPMs and Mileage\ reliability .SHOTPEENING CRACKTESTING and all MEGABUCKS.
new top and bottom everything come to think of it
LOL why dont you build a 2.5litre stroker rear wheel drive with computer yaw con too bra.