Does anyone know where I can find more specs on the jdm D15B motor? specifically the block. I have been trying to find more information, but can't seem to get the right stuff. from what I can tell the head is the same one as in the D16Z6, but the block is different. I am looking for things like bore size, stroke, rod lengths and so on. Thanks

 

http://asia.vtec.net/article/d15b/

 

I noticed nobody has posted the effects atmospheric pressure has on a boosted engine. At sea level atmospheric pressure is about 14.7psi. Most turbos and superchargers will boost relative to the atmospheric pressure. This is important because as you go up in elevation the atmospheric pressure drops. At 5K feet of elevation atmospheric pressure is about 12psi. Now what that means is the density of air at 5K feet is about 20% less than that of sea level. So when you have 6 psi of boost at sea level you are cramming air with a respective density of 20.7psi (neglecting heat related density loss factors). As you can see at 5K feet you are cramming air with a respective density of 18psi. So the engine will be putting out less hp at higher elevations. All these numbers are neglecting other factors, but you get the picture. At higher elevations the engine can handle more safe boost levels than that at lower. That is why everyone is always trying to say go by hp numbers when deciding what your engine can handle instead of boost levels. There are other factors that affect the engine much more than boost, but in the end, the hp output can give you a better idea of how much strain you are putting on your engine.

 

Thanks that was good reading, still no info on the block, but I will print this up and re-read it again to get a better idea of this engine.

 

except you have to factor in that the octane ratings will change with elevation. not drastically, but enough that on a finely tuned engine, you could have major detonation if you are using higher elevation fuel and then drop back down to a much lower elevation. like here in Sacramento, we can drive up to well over 6000ft, fill up the tank, then drop back down to near sea-level, where that extra 3/4 point of octane can be the difference in happy driving, and engine killing detonation. so low elevation (higher octane) 91 octane is good for higher elevation boost levels, but the boostctane ratios are about the same for one elevation as another.

 

I myself have never said a certain engine can handle a certain amount of "boost" because the level of "boost" has nothing to do with it. You allways see 7/8psi on a stock d series well I would love to watch someone put 7/8psi of boost on a stock d series from a dual bb T70 with 3 inch piping. It would last all of about one pull in 2nd gear. I have allways focused on tq because that is the deciding factor, horsepower and boost levels get thrown around like crazy and not one of them really matters.

The rods are the deciding factor with these engines first and formost then the pistons and head work. D series rods are tiny ranging from the smallest at 9.95mm from the obd1 usdm d15's like the d15b2 and d15b7 to the biggest 10.85mm from the obd1 D16Z6/JDM D15B and first on my upgrade list would be these no if's,and's, or but's about it.

Now for specs on the JDM D15B

stroke: 84,5 mm
cc: 1,493l
cr: 9.2:1
max power: 130hp at 6500 rpm
max tq: 107tq at 5250rpm