4G92 DOHC MIVEC wHP???

[Wajafly]

Wow.... supercharge!

Anyway, anyone can post the standard mivec dyno chart please?

 

[cooljas]

In response to what it takes to make a Mivec 1.8 go fast....
A Mivec 1.8 requires a lot of tuning. Pistons sizes have to correct, a full balance or blue print is needed, ecu tuning, higher compression pistons (But not as high as Mivec unless you have done extensive tuning) and not to mention the obvious stuff like intake and exhaust parts. That's just to get around 190hp or more at the crank. The next step is Jun Mivec cams which will blow your engine because Mivec 1.8 can not consistently rev over 8500 rpm before blowing (Too long stroke)

Deacon,
Y u say 1.8 cant consistently rev over 8500rpm?other than too long stroke is there any reason?Also y too long stroke if rev above 8500rpm, the engine will blow?Sorry i am stil new in 1.8mivec engine, care to give me some hints?Thanks

 

[deacon]

Compression is already high in a 4G93P engine. It normally runs around 10:5:1 compression ratio.

When you add Mivec pistons to the engine your compression goes up to 12:1:1 or something really close to that. In M'sia there is no high enough octane gas to power such compression.

Even if you use normal 1.6 pistons its still tricky and dangerous.

The reason being that the aforementioned pistons stick out of the block whereas the normal 4G93P pistons do not. When your high compression pistons push up there is more compression build up. In a long stroke engine that's very bad.

Think of it this way (Hopefully this will make some sense) a B16A has the same bore and stroke size as the 4G92 Mivec engine. Our 4G93P engines has the same bore size but a longer stroke than the Mivec and B16A. Which means to get the extra 200cc of displacement a lot of stroke has been added.

The longer the stroke the harder the engine needs to pump upwards to create the desired power. This creates more problems because the higher the revs the more stress the engine experiences.

For example comparing a B18C1 or B18C5 to a 4G93 Mivec hybrid. The B18C has a 84mm size piston which mean it has more bore while maintaining a shorter stroke therefore making it easier to rev.

I don't know whether this makes any sense, haha. But that's as much as i can explain.

A good piece of advice to some is maybe bore the block out and use 82mm pistons but you really need a mechanic that knows what he's doing or you're basically screwed.

 

[spyderslr]

dude,
B18C : 81mm x 87.2mm = 1797cc
4G93 : 81mm x 89mm = 1834cc

a b18c has the same bore wif 4G93 ler....cheerzz. =)

 

[cooljas]

Compression is already high in a 4G93P engine. It normally runs around 10:5:1 compression ratio.

When you add Mivec pistons to the engine your compression goes up to 12:1:1 or something really close to that. In M'sia there is no high enough octane gas to power such compression.

Even if you use normal 1.6 pistons its still tricky and dangerous.

The reason being that the aforementioned pistons stick out of the block whereas the normal 4G93P pistons do not. When your high compression pistons push up there is more compression build up. In a long stroke engine that's very bad.

Think of it this way (Hopefully this will make some sense) a B16A has the same bore and stroke size as the 4G92 Mivec engine. Our 4G93P engines has the same bore size but a longer stroke than the Mivec and B16A. Which means to get the extra 200cc of displacement a lot of stroke has been added.

The longer the stroke the harder the engine needs to pump upwards to create the desired power. This creates more problems because the higher the revs the more stress the engine experiences.

For example comparing a B18C1 or B18C5 to a 4G93 Mivec hybrid. The B18C has a 84mm size piston which mean it has more bore while maintaining a shorter stroke therefore making it easier to rev.

I don't know whether this makes any sense, haha. But that's as much as i can explain.

A good piece of advice to some is maybe bore the block out and use 82mm pistons but you really need a mechanic that knows what he's doing or you're basically screwed.

May i know y more compression will be bad for a long stroke?

b18c does not have 84mm bore...as i remember 84mm bore belongs to the b20b block......

May i ask u, wat is d highest rev u ever c on a 4G93P block bfore?

 

[deacon]

My bad i think i had myself confused with my old Accord B20B and it's 84mm x 89mm bore and stroke.

Highest rev was 7,800RPM - limiter.

Google - easiest place for answers and infinitely more reliable than myself haha.

 

[cooljas]

My bad i think i had myself confused with my old Accord B20B and it's 84mm x 89mm bore and stroke.

Highest rev was 7,800RPM - limiter.

Google - easiest place for answers and infinitely more reliable than myself haha.

Actually i've seen bfore a few 4G93P revving more than 8000rpm without a problem, maybe u should do more research on tat on www.google.com!Cheers

 

[deacon]

Umm 7,800 is when my rev cuts out. Thanks for the google tip genius.

 

[cooljas]

Umm 7,800 is when my rev cuts out. Thanks for the google tip genius.

U r always welcome!Ur rev cut at 7800rpm then ur peak power is at 7800rpm also?sorry for tis noob question...

 

[deacon]

6,900 rpm is peak, my car's peak powerband stretches until 7,300 rpm.

 

[sta]

Actually i've seen bfore a few 4G93P revving more than 8000rpm without a problem, maybe u should do more research on tat on www.google.com!Cheers

so those cars engine can last how long ? 1 year ? or 1 lap ?

 

[cooljas]

so those cars engine can last how long ? 1 year ? or 1 lap ?

On how tis engines can last how long, it all depends on da parts that u r using in the bottom block, i've seen a few cars tat last more than 1 year...if tat car can last for 1 lap, then there muz be something wrong v the mechanic!

 

[deacon]

blue print anyone?

I think it's safer to tune lower and be happy with torquey power but then again what do i know.

 

[Zeroed]

Deacon is right. A long stroke, high revving engine places a lot of stress on the cyllinder walls. This has long been one of the major debates with the VTEC guys when it comes to 1.6 VS 1.8.

With the two engine having the same bore, a 1.6 will be able to rev a lot easier than the 1.8 due to lower piston travel time and sideways piston load. Efficiency in the high rpm range is just higher.

Revving a 4G93 all the way to 8500+rpms constantly I think really is risky unless with upgraded and balaned internals. Revving the 93P engine like that is asking for trouble, long term wise. IMO lah. :)

 

[deacon]

Ahh somebody with reason and more logic than me. Now i don't feel like the only one who shares that opinion :D

 

[cooljas]

Deacon is right. A long stroke, high revving engine places a lot of stress on the cyllinder walls. This has long been one of the major debates with the VTEC guys when it comes to 1.6 VS 1.8.

With the two engine having the same bore, a 1.6 will be able to rev a lot easier than the 1.8 due to lower piston travel time and sideways piston load. Efficiency in the high rpm range is just higher.

Revving a 4G93 all the way to 8500+rpms constantly I think really is risky unless with upgraded and balaned internals. Revving the 93P engine like that is asking for trouble, long term wise. IMO lah. :)

Zeroed,
Ah yes u r correct, a 1.6 will be able to rev a lot easiear than the 1.8...but remember there is always a lot of ways to make a 1.8 to rev as high as d 1.6!Nothing is impossible if u got the cash to fool around with....

Ok at this point if we wanna high rev an engine(pls don compare with stock engine), the life span of the engine will be shorten maybe can last u 1 year or maybe less than 2 years, some cases a few months(depends on the mechanic tat build ur engine).....Also balanced internals is one of the steps to go thru if u wanna build a strong n high rev engine, but let me share v u something...i've change 3 mechanics bfore and i've rebuild 4 engines of 4G93P bfore! 2 of the engines tat i rebuild was fully balanced bfore but tat 2 engines only last me for 4months and tat time i was revving only 7500rpm..tis is to tell u guys choosing a mechanic will be very important, goin to the wrong mechanics, ull be screwed up!

And lastly let me tell u some secrets of mine...im running on a 4G93P n my peak power is at 9500rpm!Pls don ask me wat spec im running as im not gonna reveal my spec here!Cheers

 

[V8_nutter]

You should run on 4 throttle cooljas,,,or you already played it ?:regular_smile:

 

[deacon]

Let's see your 9,500RPM beast.

Is there a need for you (Cooljas) to show others up on the thread? Contribute friendly like.

 

[Zeroed]

deacon: In the west, half the world shares your opinion... and the other half are die hard oem spec reliability believers.

cooljas: 9500 rpm is amazing for a 4G93P. :O
Well with adoption of the few familiar Type-R engineering techniques, good angled and bore intakes, well profiled (not necessarily huge) cams and very high compression you should be able to obtain those figures... plus maybe a few trade secrets that I dont know of lah. Its not impossible, but keep in mind that no matter what a 1.6 will be able to handle that 9500rpms easily and a lot more reliably than the 1.8... no doubt a well sorted 1.8 will be safe as well, but with those kinds of mods on a 1.6 you'll probably be touching 10,000rpms and above with ease; taking into account careful consideration on the measurements of the internals (at those rpms, even the conrods may lengthen slightly apparantly). Its just the laws of physics in engine designs with short vs long strokes.

Of course, this is all theory, and youre right... in reality a good mechanic may probably sort out everything for you with years and years of know-how. Besides, there are also ways to strenghten the block for it to run in extreme conditions in a safer manner like Posting between outer cyllinder and block walls. The typical mechanic who believes that engines designs are durable, that inconsistency doesnt matter too much, and that agak-agak will run safe will not succeed here.

My 2 cents =)



and yup i'd like to hear that engine at those kind of speeds! Gotta be addictive.

 

[deacon]

I was gonna say something less than friendly but ended up with what i said. Zeroed i think you hit that on the dot.