B20-CRV VTEC - Why it Blows.....

pencalat

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pencalat

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overrev?
can i know your shifting point?
stnd internal?
aiyoh...
frankly speaking... my english not good enuff..
sometime certain word that i didn't understand...
more over in matter of car issues.. i always wrong predict...

shifting point that what rpm that i shift tha gear kah??
 

jeheyr

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jeheyr

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aiyoh...
frankly speaking... my english not good enuff..
sometime certain word that i didn't understand...
more over in matter of car issues.. i always wrong predict...
shifting point that what rpm that i shift tha gear kah??
aisey... mine also not so good..
yeah, thats what i mean.. rpm when u changed gear..
one more.. u still using standard CRV piston?
 

dcloo

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dcloo

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Piggyback applies what we call a lambda on the original fuel mapping.

remember the tables your tuner looks at?

as an example,
The RPM is the 1000,2000 value, called the RPM index,

The 1, 2, 3, 4, is the load zones (or load index), some, like the PowerFC, uses numbers, while hondata, uses actual units (it doesn't matter really) Most piggybacks just use TPS to simulate the load index, like VAFC, Neo, etc. which means a little like guessing where the computer is ACTUALLY reading the map from.



You can also replace the load zones with TPS indexing on standalones, but usually that's done for running quads, because they can't have good part throttle (on/off driving) at low rpms due to lack of good MAP signal (it's doable, but well, what's the benefit of running quads with a tuning method designed for manifolds?)

That's why that's there manifold versus ITB, which is better? debate down in honda-tech, I think.

Back to topic. Well, what the piggyback does is apply 'adjustments to the map'



Like emanage, and unichip, they work in this method. They add adjustments to the original mapping, which is all good and fine, if the original mapping is static.

The thing is, the mapping of honda ecu's in open loop mode is not static, (for the most part, at near to full throttle it's static) it changes from time to time, courtesy of it's long term and short term fuel trim. I think powerFC does this feature the best as an example, just start and wait for it to find it's own idle during intial setup. That is a more extreme example of how it works, but even the stock honda ecu's have that feature, although not at such a high correction rate.

But it's not like piggybacks are bad, they are good for minor adjustments, esp when the original ecu mapping is suited to the engine, but just need a little tweaking.

In the B20B case, most of the ECU's used, the original mapping is for the B16A, imagine what kind of adjustments are needed for that, and what kind of fuelling changes the original honda ecu will do as time goes by.

having a static lambda (fuelling adjustment) while the stock keeps adjusting itself, it's like trying to swat a moving fly while driving a car in the rain. lol. those raindrops and the fly start to blend in.. and both are moving, so you can't really see where the actual fly is.

I'm not sure if the newer gen piggybacks start tricking the 02 into a closed loop mode yet, but if you're the curious type, if D14 on the P30/P08 ecu is connected to the piggyback, then it probably is. I think that's probably one way to get around it, but well, originally piggybacks were made to map more accurately the original mapping (cleaning up the mapping due to added mods that changed the flow of the engine, when the original cannot cope anymore)

I don't think it'll ever come to that since it's like the piggyback trying to become what it's not, but well, just thinking out loud.

Well, that's just a small aspect of tuning. Now I know why mat salleh find it so fun. :P
no matter what stand alone ECU/Piggyback you tuning your car running in 13.5:1 < CR with pump gas (petronas,sheel,mobil,bla bla bla) daily driving confirm your piston will melt/blow your engine

some sample picture show below using wesico 12.5:1 CR and skim head&block and around 13.5++:1 CR after 15000 KM tune with microtech LT 10s


 
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pencalat

500 RPM
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pencalat

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aisey... mine also not so good..
yeah, thats what i mean.. rpm when u changed gear..
one more.. u still using standard CRV piston?
hehe... for the moment of my pow sin chee b20b... yup i used the std CRV piston..
i've changed almost at 9k at that time maybe more... didn't rememberlah...
then... kaboom la... asap putih from front bonnet.....
conrod patah... head terangkat... 1 best part is i can see my piston...
hehehe....
 

Northiswara

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Northiswara

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hehe... for the moment of my pow sin chee b20b... yup i used the std CRV piston..
i've changed almost at 9k at that time maybe more... didn't rememberlah...
then... kaboom la... asap putih from front bonnet.....
conrod patah... head terangkat... 1 best part is i can see my piston...
hehehe....
soli to cucuk half way in but curios. :idea:
u use what head? b16a? b18cr? b20b head?
 

jeheyr

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jeheyr

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hehe... for the moment of my pow sin chee b20b... yup i used the std CRV piston..
i've changed almost at 9k at that time maybe more... didn't rememberlah...
then... kaboom la... asap putih from front bonnet.....
conrod patah... head terangkat... 1 best part is i can see my piston...
hehehe....
fuhh.. with stnd p3f piston rev until 9k..
thought b20 will lost torque after 8k rpm..
is it true dcloo/hattech/shiro? - consider using stnd internal part(no jun/skunk/whateva)..
 

dcloo

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dcloo

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fuhh.. with stnd p3f piston rev until 9k..
thought b20 will lost torque after 8k rpm..
is it true dcloo/hattech/shiro? - consider using stnd internal part(no jun/skunk/whateva)..
this happen normal where the con rod bearing was wear out and cause the jam then only the rod will broke 2 pcs cause he mention he still saw the piston, if piston was break u can't even saw a complete piston on high rev cause will hit the head and rod will crack in 1000 of pcs and if you think to rev so high always recommended change to better bearing like ACL race bearing/stock type r bearing its reduce the risk of bearing worn out in such high rpm This i have did a b20b for my customer and equip with toda C cam went to track days 5 times with P3F piston and the engine still very healthy no white smoke/silence engine condition and its just service his car every 5000 km
 

shiroitenshi

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shiroitenshi

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Usually head won't terangkat unless even the head bolts fail spectacularly (I think it's unlikely, there's 10 of them, and if you were cheapskate enough to REUSE them that often, I have NO COMMENTS.)

Blown engine usually means a broken rod, the rod will whack the liner and eject a chunk out of the side of the block. That's why most blown engines will always have a hole at the block. It's not the pressure that makes the hole, it's the broken rod. This is probably the most common damage I see on B16a shortblocks, which is usually traceable to the owner deciding that 9.5K rpm is a good idea on stock valvetrain, and installing an ecu without a revcut.

There's also the valve dropping part. This one is the piston has a hole, the rod may or may not break (but it will at the very least be bent beyond repair). The piston has no melted edges/VERY pitted surface that are the telltale signs of detonation.

There's also improper installation. The signs will be almost like the valve dropping, except in this case, it's the pistons hitting the valves at high rpm. Cam and stroke cycle = not enough minimum clearances. The rods stretch at high rpm, so if the valves don't touch the piston during installation, there's no guarantee that it won't at high rpm. I think the minimum clearance is quite large for high rpm engines, in the region of 3mm+, esp when they are degreeing the cam.

There's also hydrolocking, which can be due to driving over puddle and the intake sucking in quite a bit of water, this one also can break rods, and etc. Hydrolock can also be caused by leaking gaskets, though this is probably not as common.

There's others, but I'm sure others can contribute.
 

pencalat

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pencalat

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aiyah bro jeheyr...
wat i get if i tipu2...
u can go to danau kota n see my car over there...
sangkut almost 2 month...

what people say in malay? "x caye pi tgk sendiri"
hehehe.... don't get angry arrr......
 

sybaritic

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sybaritic

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fuhh.. with stnd p3f piston rev until 9k..
thought b20 will lost torque after 8k rpm..
is it true dcloo/hattech/shiro? - consider using stnd internal part(no jun/skunk/whateva)..
it can be done..........................but d power might be loss b4 8k rpm.........:itsme:
 

pencalat

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pencalat

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hehe... not daily scary....
on that day i got satan in my head...
:biggrin: :biggrin: :biggrin:
that's y it's blown.. hehe...
 

dcloo

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dcloo

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2k++...
interested?
how come u interest wth 84mm/85mm?
u said ure using b16a...
:rofl:
b16a block also can you 85 mm piston with 89 stroke thanks for malaysia engineering shop
I dun believe until i saw it with my past 2 years ago
 

D-IV

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D-IV

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dcloo,

Thats a pretty interesting piston crack. Only one side affected and ringland didn't seem to break that hard. How was the rod condition on that piston?

As a summary:
Improper built engine + shitty tune + revving the piss outta the engine is formula for blown engine already.

Anyway shiro, you got pm.
 
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