4g92p block into 4g91

[iswara204]

4g91,92 and 93'ers..pls do come in.."rojak planning"

*not sure whether this topic have been discussed*
Guys, after so many halfway canceled minor projects,finally able to collect some cash for some minor modi now..So just need some 2cent from u guys out there..

Current engine : 4g91
Mods : 4g92p or 4g93DOHC block and the internal

Power and Durability wise,Worth the drop in annot?

At the same time, i have doubts in certain areas which is

1) How does the compression ratio plays the part here. What should i go for since 4g91=9.5:1

4g92p/SOHC : 10.0:1
4g92DOHC : 11.0:1
4g93DOHC : 10.5:1

2) relationg to question1, the higher the compression is, the better it is right? correct me if im wrong. So if im gonna drop in the 4g92p(10.0:1) and wants the compression ratio be a lil higher (close to 10.5:1),should i add a thinner metal casket to make it a lil higher?

3) Comparing the piston stroke,
4g91 : 77.5mm
4g92 : 77.5mm
4g93 : 89.0mm

which is better?shorther stroke length or longer?

thanks for reading and commenting guys....app it..Good day!

 

[Turbo676]

2) Yes. When u say 'better' i'm assuming you want more power. However, the law of diminishing returns would apply. So NO if your 4G91 has a static compression ratio of 14:1, the only thing u would be getting is a blown engine.

Thiner metal head gaskets, raise the compression ratio of an engine. The metal headgasket sits sandwiched between the head n block. having a thinner gasket reduces the volume of the combustion chamber thereby increasing the ratio.

3) Assuming the bore of the 4G91 is the same as 4G92,93 ie 81mm, the stroke for the 4G91 would be around 74mm. Y r u asking this? Usually more stroke = more torque. HP = Torque x RPM. higher torque = More power.

 

[iz282]

2) Yes. When u say 'better' i'm assuming you want more power. However, the law of diminishing returns would apply. So NO if your 4G91 has a static compression ratio of 14:1, the only thing u would be getting is a blown engine.

Thiner metal head gaskets, raise the compression ratio of an engine. The metal headgasket sits sandwiched between the head n block. having a thinner gasket reduces the volume of the combustion chamber thereby increasing the ratio.

3) Assuming the bore of the 4G91 is the same as 4G92,93 ie 81mm, the stroke for the 4G91 would be around 74mm. Y r u asking this? Usually more stroke = more torque. HP = Torque x RPM. higher torque = More power.

Good explain bro...

 

[iswara204]

2) Yes. When u say 'better' i'm assuming you want more power. However, the law of diminishing returns would apply. So NO if your 4G91 has a static compression ratio of 14:1, the only thing u would be getting is a blown engine.

Thiner metal head gaskets, raise the compression ratio of an engine. The metal headgasket sits sandwiched between the head n block. having a thinner gasket reduces the volume of the combustion chamber thereby increasing the ratio.

3) Assuming the bore of the 4G91 is the same as 4G92,93 ie 81mm, the stroke for the 4G91 would be around 74mm. Y r u asking this? Usually more stroke = more torque. HP = Torque x RPM. higher torque = More power.

Thanks bro..
Well, this is wat im planning to do.
Compression ratio
4g91 = 9.5:1
4g92SOHC= 10.0:1
4g92DOHC= 11.0:1
4g93DOHC= 10.5:1

So im planning to drop in the 4g92SOHC (10.0:1) and add a thinner metal casket to make the compression ratio close to 10.5:1...this is wat i understand..is this the correct way??

4g91's stroke length is 77.5mm same as mivec's..the bore is 78.4mm. 4g92and93's bore is 81mm.

Understanding the bore and stroke, i understand A piston engine is oversquare or shortstroke if its cylinders have a greater bore (width, diameter) than stroke (length of piston travel). This is generally considered to be a positive trait, since a longer stroke means greater friction and a weaker crankshaft. An oversquare engine is generally more reliable, wears less, and can be run at a higher speed; though with the aid of modern technology, the disadvantages of undersquare or longstroke engines have been overcome. In oversquare engines power does not suffer, but low-speed torque does to some degree Stroke ratio - Wikipedia, the free encyclopedia

 

[iswara204]

and guys, what abt the timing belt uh? can i use back 91's if i droping in the 92 block?

 

[Turbo676]

dude, i think there's too much emphasis on static compression from your end. Since the stroke for the 4g91 and 4g92 is the same, y not go for 4G92 pistons instead of swopping the entire block? save the hassle on re-registration of your engine.

if i'm not wrong, the 4g series blocks run close deck cast iron blocks which should have sufficient 'meat' to run 81mm pistons (an increase of only 2.6mm).

Can anyone verify if the deck height of the 4G91 is the same as the 4G93? If yes, then the crank n rods from the 1.8 could technically fit in as well. Ahh....a stroked n overbored 1.5 :)

 

[boyzone]

my brother engine is rojak by mivec block with 91 head.
So far running well.

 

[calvin9683]

i'm using 92SOHC block for my 91 now.......
initially upgrade injector n throttle body....
but then the driving feel is not really fun la.....
wat i can say is dat the power is kindda linear....
not like ori 91....can feel the pull after 4k rpm.....

then do up some other mods....
pnp, setting cam n piggyback.....
end up oni got a fun to drive car.....

a lot ppl will say y not bore n fit 81mm piston....
coz 91 stroke is same as 92.....
but then there's always the question of reliability la.....
everyone got their own ways of doing....
somemore changing block is faster than send to do rebore.....
correct me if i'm wrong on this.....

anyway...
there;s a tendency to regret la....
so i'd suggest u to go all out....
93 kasi sama dia.....
happy modding.....

 

[iswara204]

im more to realibility kinda person. i rather drop in than rebore..hassle free

calvin9683- bro,so wats the total cost of the 1.6 modification uve done?can u break it down?u can pm me if u don want to discuss here..hehe..is the power better than 4g91 now? since u have drop in a 1.6, are u happy with the power u have now or u think it would produce more power if droped in a 1.8 earlier?

 

[iswara204]

dude, i think there's too much emphasis on static compression from your end. Since the stroke for the 4g91 and 4g92 is the same, y not go for 4G92 pistons instead of swopping the entire block? save the hassle on re-registration of your engine.

if i'm not wrong, the 4g series blocks run close deck cast iron blocks which should have sufficient 'meat' to run 81mm pistons (an increase of only 2.6mm).

Can anyone verify if the deck height of the 4G91 is the same as the 4G93? If yes, then the crank n rods from the 1.8 could technically fit in as well. Ahh....a stroked n overbored 1.5 :)

the realibility is not confirmed if the block is rebored to fit in the 81mm pistons..i might aswell just go for the block,save the hassle and worries..haha..

 

[badgti]

bro,

the 4g91 block can be bored to accept the 81mm pistons as it has enought meat to do so, 4g91/92/93 are all same blocks except that the 93 has a longer stroke a the block height is slightly longer, i am using a 4g91 bored to fit 81mm mivec pistons and a 4g91dohc head.runs good but u really need a slightly thicker headgasket , use stock 1.3mm headgasket or thinner but don't use the 0.5mm ones that are commonly sold as it'll give a lot of problems with your engine constantly knocking.with this setup u should be looking at a good CR of maybe 11.0:1.
cost of doin all of the above:
rm250 mivec pistons
boring rm80
new bearings (crank and conrod)-rm200( i think)
metal head gasket-rm2++
or ori mitsu 1.3mm gaskt-rm200
the rest is lbour for installation

the above costing is estimated costs for the parts u need.

 

[calvin9683]

well...
i'd say the fastest way to do it is to change block.....
coz its somethin like take out the 91 block...
n put back the 92 block....

if u were to send for re-bore n change the block internals.....
more time is needed lo....
n another question is...
the machine shop need to do it properly....
if not accurate...
u might b facing never-ending probs in the future....
if u dun need to use car urgently n can leave ur car at the workshop for some time then y not??
as the cost looks around the same.....

n also...
less hassle in the sense of registering lo....
coz if u change block....
its either u go n re-register...
or u ketuk ur engine number (n worry bout JPJ).....
if u do up ur ori block...
then no need to worry abt the engine number......

so...
the choice is urs la...
heehee

 

[iswara204]

bro,

the 4g91 block can be bored to accept the 81mm pistons as it has enought meat to do so, 4g91/92/93 are all same blocks except that the 93 has a longer stroke a the block height is slightly longer, i am using a 4g91 bored to fit 81mm mivec pistons and a 4g91dohc head.runs good but u really need a slightly thicker headgasket , use stock 1.3mm headgasket or thinner but don't use the 0.5mm ones that are commonly sold as it'll give a lot of problems with your engine constantly knocking.with this setup u should be looking at a good CR of maybe 11.0:1.
cost of doin all of the above:
rm250 mivec pistons
boring rm80
new bearings (crank and conrod)-rm200( i think)
metal head gasket-rm2++
or ori mitsu 1.3mm gaskt-rm200
the rest is lbour for installation

the above costing is estimated costs for the parts u need.

thanks for the cost breakdown n the info's bro..but say im lookin into having a 1.6(CR is 10.0:1)block or 1.8(CR is 10.5:1) block. Whats the casket size should i go for to make it 11.0:1....btw the how does the calculation works..blur la bro..haha..