2.1 litre high rev engine

[cheekychimp]

There have been a few posts about engine rebuilds recently and a lot of guys seem to be going the stroker route, putting the 2.4 crank in the 2.0 litre block.

So has anyone actually done the opposite and put the 4G63 crank in the 2.4 litre block? I have been reading more and more about this and a 2.1 litre engine with a 10,000 rpm limit sounds like it would be an absolute screamer.

To be honest I'm surprised more people haven't tried it. What's the bad side?

 

The transmition is the problem. It wont last long and most likley wont shift at 10-11k.

 

[JB]

what about a dog box?

 

Well thats what easy $4000

 

[cheekychimp]

Yeah it's a lot of money, no doubt about that ... BUT just in theory what could you expect from that combination.

We've got an extra 100cc displacement to spool a marginally bigger turbo but I'm worried here about whether we'd get anything to spool by 4000 that was going to be able to flow enough air for 10,000 rpms.

Any ideas?

 

Quote:
There have been a few posts about engine rebuilds recently and a lot of guys seem to be going the stroker route, putting the 2.4 crank in the 2.0 litre block.

So has anyone actually done the opposite and put the 4G63 crank in the 2.4 litre block? I have been reading more and more about this and a 2.1 litre engine with a 10,000 rpm limit sounds like it would be an absolute screamer.

To be honest I'm surprised more people haven't tried it. What's the bad side?



So, if the 4g64 block has 6mm more deck height and there are 1.13" compression height pistons available (for 100mm stroker in short-deck g63 block)...

and we use:

88mm stroke g63 crank

in 6mm taller g64 block

with 1.13"CH stroker pistons

we could use a (custom) 12mm longer rod or perhaps, even a little bit more and run the pistons flush or even out of the hole a little. But we will assume this rod to be 150mm (stock) + 12mm (gain) = 162mm rod length.

4g63 rod ratio = 1.70454545
theoretical hybrid rod ratio = 1.84090909

and the graph is a plot of piston acceleration for:

the short rod and long rod on short stroke

and the blue line represents the stock rod on the 100mm (long) stroker for reference

and the green line represents and unobtainable 200mm rod length, for our purposes infinite.

all using 10000rpm suggested rev limmit:




Those two lines that almost trace over eachother represent the difference between this golden-child block and a stock 4g63. So unless there is a magical quality in the combination of parts you have suggested that eludes me, it would be utterly pointless to go to the trouble of making these 162mm rods. They would be heavier which would probably negate any benefits. They would cost a little bit more than off the shelf units too (think kidney/lung/heart, at least in Villivakkam.)

Plots for piston velocity are similarly uneffected.

The stock rod ratio is already beautiful. The valve's (large) included angle is what makes these things rev turds. But then again, looks very close to b16a included angles. I'll have to continue this investigation.

Oh yeah, I didn't spec any pin offset which would skew results but not substantially up or down, just a fraction of a degree of crank angle.

 

Finally someone is here to play myth busters with the whole 2.1L question.

 

[cheekychimp]

So what are you saying? That this combination doesn't offer any significant evidence to suggest it is any more likely to be capable of being revved to 10,000 rpms than a standard 2.0 litre?

 

Quote:
Yeah it's a lot of money, no doubt about that ... BUT just in theory what could you expect from that combination.

We've got an extra 100cc displacement to spool a marginally bigger turbo but I'm worried here about whether we'd get anything to spool by 4000 that was going to be able to flow enough air for 10,000 rpms.

Any ideas?



The turbo is definately an upper limit for flow in application, but there is something fundamental making the 4g63 rev-challenged. I have not seen many dyno charts with torque peaks beyond 5250 RPM and beyond 6krpm, forget about it.

Perhaps the 88mm stroke is already relatively long which produces piston velocities that outstrip the ability to accelerate air from the plenum... The 74mm stroke of the 4g61 looks promissing. If it were a direct fit, 1.7l of displacement would be available. With 87mm pistons, 1783cc available. That is where it's at. I am switching to colt/mirage platform tommorow.

 

I am saying just that. In fact, I beleive that the additional piston mass and rod mass (upstroke and upbore) will contribute to less rev-ability.

 

[cheekychimp]

Well Magnus' pistons are supposed to be lighter with that very fact in mind, but I can't argue with your figures especially since you quoted the exact 162 mm rod length that a lot of the 2.1 destroked motors carry.

I guess that's why a lot of guys on the other side of the fence consider this option to be a huge waste of potential of the 2.4 litre block.

Makes some sense though. I often wondered why 2.0 litres were the fastest. I figured maximum speed had to be a product of rpms. The faster the engine and then the gearbox is turning the faster the wheels go.

 

I typed up a long post but deleted it. The combo defintely has it's advantages to me but until someone puts their money where there mouth is I suppose it's all bench racing. The reason I didn't build one is because I want to try the 2.4. But if that goes bye bye one day maybe I'll try the 2.1 since I already have a dogbox. I can't wait to see how one here in Colorado works. I'm not in control of the budget or timeline so don't ask me when it's going to be done. I'm just technical ASSistant.

 

[147/1000]

What about a 2.3l going to 9k RPM. Would there be any benifits or draw backs? I have read that you dont need to rev a 2.3 past 7.5k but would it be pointless to go to 9k? I havent read of any one accually doing this and if I can get some kind of evidence that it would be benifical im willing to try it.

 

I see little benefit to this 162mm rod motor unless there is serious overbore potential in the 4g64 block that the g63 and g61 blocks don't have. Since the nature of this question was RPM, I would think that you fellas are seeing some substantial RPM ceiling change with the extra rod ratio that just isn't there. I don't know if you think most of that will come from aspiration/geometry relationships or straight peak piston acceleration/rod breaking relationships.

The 1.78l destroker on the other hand, look tricky too. At the same limmit of piston acceleration, the 2.0l will only be at about 10% less RPM. The displacement of the 2.0l is more than 10% greater, however. That coupled with the fact that friction on the destroker at 10% higher RPM will also sap some power and It will be harder to obtain the same VE at higher RPM (in my opinion) makes the 1.78l look doggish.

The peak piston velocity on the 1.78l will be 7% lower though.

What does that mean, I have no idea whatsoever. Maybe easier to aspirate?

(the 2.1l long rod motor, like I said, has roughly the same peak piston velocity as 2.0l, doesn't apply there)

 

Since we are bench racing, it is important to realize that ther is alot more to this than piston acceleration. How do these different combos relate to piston dwell time, piston/cylinder wall friction, and thermodynamic effects?

Factor those into the equation, and the differences may be greater.

 

This really is horrible bench racing but to claim that 162mm rod is improvement requires justification. I can't make that justification. This is such a minute detail. I think there is more power and durability hiding in a thousand other systems in the car:

poor injector location.
stupid intake runner floor.

stupid utilization of available combustion chamber quench area
typical wastegate configuration is rediculous (i have one that is tapped off one runner he he he).

oil pump system
oil drainback
windage

especially crankcase ventilation (possibly vacuum pump)

crank harmonics and damper

water pump/cooling system

ring tension
ring sealing
piston gas porting?
skirt design?

what have you...

In regards to reving a 2.3l to 9k. Of course there are benefits if you can get it to aspirate and stay together. Neither of which I give high probability of success to, given the current state of technology.

 

[HHIVR4]

SBR is selling a destroked 2.1..It would definately require a heavily modded trans to keep up..Seems to me there are alot of other factors involved ..I dont really think it would be worth it in the long run..For the price you can get the stroker and for the money the 2.3 or 2.4 gets my vote..
Here

 

[CO VR4]

There are alot of 2.0 DSM race built motors that rev in excess of 9K. The limiting factor in the stock motor is the strength of the rods and factory cast pistons. The rod ratio is near that of the 2.0 liter for the 2.15 short stroke long rod motor. Magnus sells this combination and pistons that are well designed for this application

 

[GVR-4]

I don't think there is much advantage to revving these engines past ~7500 rpm. Start looking at some dyno charts and checking to see where power falls off. The power band seems to be between 5000 and 7000 rpm. I know there aren't many (if any) 2.1 dyno sheets available, but there are lots of 2.0 liter charts around. I've got the May 2004 issue of Sport Compact Car and there are 9 dyno charts of different modified Evos and peak power for all of them came before 7k. It seems the engineers designed the head, cams, manifolds and turbo to work best between 5 and 7k. I know these can all be modified and/or changed, but it seems to me you would be redesigning the engine.

Just my $.02.

 

Yes!!! You must redesign to make use of any built motor but a 2.0 or 2.1L for sure. You can make power with revs or displacement. If you do it with revs you need a good valvetrain and cams! 4g63 cams as a whole suck for high high rpm use. Honda's own us in that department. Taking a good long look at what head you use is important too.