Question for modified 4B11 NA Guys

Hey folks .
I am looking for someone who knows what they are talking about.

To make a long story short I am looking at using the 4b11 Naturally aspirated motor in a mirage cup car as the 4g93 mivec motors just are not cutting it anymore and can not keep up to the k20 motors.

Now my questions are:

What kind of engine problems are you guys getting ? are your timing chains stretching/ tensioners failing.
Any head gasket / cylinder sleeve cracking or oil Pressure issues etc.

From what information I have gathered the 4b11t head flows just as good as a k20 at 280 cfm but the problem is that even the biggest evo camshaft available does not come close to the stock k20a camshaft.
My question on this is has anyone measured the max lift before coil bind or valve stem contact on the 4b11 head?

Also just to add that compression is not an issue and this engine does not need to have everyday drivability it will spend most its life above 5000 rpm.

Cheers Brendan
 
Is there a cc limit preventing you from going 4B12?

K20 is variable lift and a 6 speed FWD transmission.
You don't have that in a 4B1X series motor and sadly I am not sure that it'll be competitive in any way compared to a K20.

As far as max lift etc Evo X forums should be able to tell you.
Lift is calculated in so many different ways though and I am not sure it takes into account the rocker arm ratio so comparing what the K20 has may not really clear anything up
 
Is there a cc limit preventing you from going 4B12?

K20 is variable lift and a 6 speed FWD transmission.
You don't have that in a 4B1X series motor and sadly I am not sure that it'll be competitive in any way compared to a K20.

As far as max lift etc Evo X forums should be able to tell you.
Lift is calculated in so many different ways though and I am not sure it takes into account the rocker arm ratio so comparing what the K20 has may not really clear anything up

Yes the class has the 2 litre restriction so that rules out 2.4
6 Speed is not an issue.
Variable lift does not increase overall power it just helps getting up in the revs / makes it idle nicely / allows a relatively high powered engine pass emissions.

The 4b11 is shim and bucket type so no rocker ratio to consider there .

Thank you for your reply.
 
You are right about variable lift not helping in outright power but it helps in spreading the torque which for race applications K20s would likely run cams such that the primary made its peak power around 7k and then the secondary would make peak power at say 8.5k.
Without the variable lift the 5,5k - 7k range which you'd spend a fair amount of time in on the track would be making less power that with variable lift.

I like the idea of a 4B11 though as it is a lightweight engine which should help handling.
I have seen photos of one in Puerto Rico fitted into a coupe but not much info on it.

Have you considered 4G63 with Evo IX head?
 
You are right about variable lift not helping in outright power but it helps in spreading the torque which for race applications K20s would likely run cams such that the primary made its peak power around 7k and then the secondary would make peak power at say 8.5k.
Without the variable lift the 5,5k - 7k range which you'd spend a fair amount of time in on the track would be making less power that with variable lift.

I like the idea of a 4B11 though as it is a lightweight engine which should help handling.
I have seen photos of one in Puerto Rico fitted into a coupe but not much info on it.

Have you considered 4G63 with Evo IX head?

Sorry my friend but your information is somewhat incorrect the typical vtec point in a b series or k series is the 5 to 6 k depening on the cam used.
Again vtec has noting to do with all out power trust me on this as I have built many engines and dyno'd them.

Your idea with the 4g63 is one that I had tossed around but the basic design of the engine ie the 88mm stroke and 85mm pistons does not make it a good candidate for an all motor engine.
The k20 features a design developed by Toyota in the 3sgte engine which is 86mm stroke and 86mm bore which is referred to as a square engine design.
The 4b11 also shares this design of 86 x 86 and the intake valves are the same size as the k20 but the exhaust valve is 1 mm smaller which will not be an issue.

Without getting to tech about how the 86mm stoke reduces piston speed and power lost from friction due to piston speed you get the basic idea that on paper the 4b11 with its all aluminium engine looks like a very good option which is why in my first post I asked about the reliability of the engine and the bucket to valve stem clearance .

Thanks Brendan.
 
Why not use a 4g64 tall block to make a 2.0L?
A good suggestion and I have looked at those engines and they will not suite my needs because they have a 86.5mm bore and if you put in the 88mm 4g63 crank you are at 2068 cc which is outside the 2000 cc class.
Besides the cc the engine just does not suite Naturally aspirated reliability with its balancer shaft and its over all weight.
I have also built a 4g94 13 to 1 comp block with a 89mm crank from a 4g93 and 157mm long rods to make up the deck height.
The idea was simular but it ended up down on power compared to straight high comp 4g93 or 4g94.

Now a lot of that could be put down to port and valve sizing in the 4g92 mivec head which in itself is another thread.
Also the age and the supply of parts are drying up.

Its time for a new engine and on paper the 4b11 is looking the best option right now.
 
So the 4G94 block with 93 crank didn't do too well?
I would've expected that the better R/S ratio would've helped.
That's one thing that I always thought Mitsubishi did very wrong in their 4 cylinder engines as they used something like a 1.5 R/S ratio which is less than ideal.
Honda for their B series used something like 1.7 and their B16B motor was a 1.8 block with but shorter stroke for more rev potential.
The 6 cylinder Mitsubishi engines generally have good R/S ratios though.

As for VTEC/MIVEC not making any more outright power, yes I agree with this.
What I am saying is that if the primary and secondary lobes are very close to one another in lift/duration and hence the changeover point is really high you will have more usable torque and power on the track.
I understand that stock cams in a K20 would negate the point of variable lift as you would always be above the 5,500rpm point and would never drop into the primary lobes.

Without going too off topic I think the 4B11 engine is good and just seeing what the Evos can do it's clear it will be reliable especially in NA form.
I have read that their chains stretch and have caused blown engines so definitely swapping in new chains would be ideal.

There aren't many 4B11 owners on this forum so you'd likely get better and more responses from Evo X forums and latest gen Lancer forums.

Make sure to keep us update with your progress and post many pics.
I've always wanted a 4B12 Asti... it'd be incredibly fun with that kind of power/torque and better weight distribution
 
Early 4B11 had stretch problem with cam chain current and late models, no problem, heavier chain. not sure from when!
 
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