DeVIIIn

2003 Evo 8 GSR
Spun a bearing recently and I’m doing a full overhaul. I have new oil pump, strainer, cooler and filter of course. I’m going to leave stock cams and valves for the time because it’s still somewhat budget. I have a little rust around the car because it spent some time up north but nothing catastrophic. New exhaust studs for that. And I’m getting ARP head studs. Looking for recommendations on replacing the balance shaft and whether or not it needs to be new or if I can leave the old one in. Also looking for recommendations on rotating assemblies. Brands, strokes, bores. I’m new to the engine building thing so any comments are helpful! Also for the time I’m keeping stock turbo and exhaust manifold. I’ll worry about those and any other bolt ons later. Also remote tuning recommendations would be great! I don’t have any import tuners local.

LetsGetThisDone

iTrader: (1)

I wouldn't build a 100mm motor. Stick with a 94mm crank, you can still run 150mm rods with the appropriate compression height piston (I think CP makes a shelf piston for this combo). Eagle forged is a great crank, rods will depend on torque/power goals.

Balance shafts should be deleted.

kikiturbo

manley and, IIRC, CP even have 2.2 pistons that wotk with 156mm rods in g63

LetsGetThisDone

iTrader: (1)

I would not use a 156mm rod with 94mm crank. The short compression height does not work well. There is a reason English Racing spent the money to use custom 153mm rods when they were first developing the combo.

DeVIIIn

Theres an import engine builder not too far from me that recommended a 4g64 crank, so 100mm stroke, 85mm pistons and 150mm rods. What does anyone have to say on that?

kikiturbo

well, that is your usual affordable 2.3 setup. I would bore to 85.5 while you are at it..

ronaldo9

iTrader: (2)

And there's a reason letsgetthisdone said to stay away from the 2.3. If you insist on using the 100mm crank I'd at least opt for 2.4 long rod but then you'd need a 4g64 block.

Evo9isLife

The 100mm crank with a 150mm rod creates a poor rod ratio, increases piston speed and cylinder side loading. All are things you want to avoid for longevity

LetsGetThisDone

iTrader: (1)

I mean...

DeVIIIn

What are the downfalls of 100mm? Where would you recommend I find that stuff? Every kit I find just seems like they’re 100mm or like crazy big pistons or stupid long rods that or they’re just factory length and I don’t understand how they would end up upping displacement. I know these are probably dumb but I’m trying to figure it out haha

cficare68

iTrader: (6)

I love my 2.4. JE Piston, BME Aluminum Rods, and 100mm Crank. The torque is awesome and still able to rev it to 9k with no issues at all.

LetsGetThisDone

iTrader: (1)

The 100mm crank in the 4g63 block has a horrendous rod ratio and is hard on rod bearings.

You can give English Racing a call, they can set you up with a rotating assembly.

alpinaturbo

iTrader: (5)

The Honda motors that rev to 9000rpm stock have what you term more HORRENDOUS Rod Ratio, and Evo X stock has worse rod ratio than 4G63.
Its a number.

If I knew nothing about the engines, like my wife, and heard this comment, I would of course take it for granted and unfortunately make assumptions and choices guided by such strong words.

I think we have to be more objective than that.


Perhaps we should say that "on paper" the 2.3 on 4G63 has rod-ratio which seems less desirable?

However, in reality, there are many successful road and race Evos running the very 2.3. Additional benefit is improved spool gained by 100mm crank over 94mm crank.


You can have your opinion and voice it of course, but I would not want a new-to engine-building fella here to take this Horrendous term for gospel, because it is not a true-statement in engineering terms.

Nobody has ever measured, that I am aware of, the actual difference in longevity under certain use of 2.2 vs 2.3, 94 vs 100 mm strokers.
We have seen graphs of theoretical side loading.
But as they say, the proof is in the pudding, and if anything, the proof in the pudding suggests 2.3 works just as well as 2.2 for virtually all.


My $0.02 cents as they say.

I love the 2.3, and unless I had a race car living at 10K rpm I would not go 2.2.
The loss of spool and low end torque, the fact that 2.3 will happily rev out to 8500 and that cam and turbo choice virtually dictate the efficiency range up to 8.5K rpm...means that we realize most benefit on road and road-course, form 2.3.

Which is why RRE and similar road-race oriented shops favor 2.3.

Evo8cy

Although in theory rod ratios do affect negatively or positively the efficiency and longevity of an engine, in reality that effect is not so crucial. In reality, 2.2, 2.3, 2.4 configurations work well, when build right. It is all down to what one wants from his setup and his intended usage of it.








Marios

LetsGetThisDone

iTrader: (1)

2.3 rod bearings, pistons, and cylinder walls always look worse than 2.2 stuff, every single time. There is a reason some shops don't even build 2.3L's with the 4g63 block, and some of those shops actually set records.

You give maybe 200rpm for boost threshold with a 94mm crank instead of 100mm. And the motor is a happier one.

The Hondas youre referring to don't have a 1.5:1 rod ratio. They are all 1.55 or better. B18 for example is 1.58:1 (close to 2.2slr 4g63), K20 is 1.62, K24 looks to be among the worst at 1.54.

Things also get much different when you're talking boosted vs N/A. There's a lot less load on the rotating assembly in an N/A application since they generally don't make as much power per liter.