2.3l better than 2.4l?

[delta448]

How exactly does this setup do that? I'm just trying to understand how/why this works so well.

Well, it's not technically the same for either, but it's the best compromise between optimizing each of the two since they're generally opposites.

Dennis already noted the biggest points, so I'll just add a little:

More lever arm length (crank throw) with the same amount of force (combustion pressure) applied to the end (rod journal) generates more torque. Same holds true when you use a cheater pipe on a wrench. I'm sure you don't need me to elaborate even this much. It's the basic principle of why increasing stroke on any engine is so beneficial.

The 94mm crank splits the middle between the 100mm (2.4) and 88mm (2.0) perfectly. When you couple that with the 2.4 block made to accommodate a 100mm crank, you use longer rods and end up with a rod ratio that is nearly the same as a 2.0 4G63.

You can use up to or slightly more than a 159mm length rod with a 94mm crank and custom wrist pin location piston. A rod length of 159mm with a 94mm crank would give a rod ratio of 1.69. Chris's 156mm rod gives him a ratio of 1.66. For comparison, a stock 4G63 with a 150mm rod has a 1.70 rod ratio and a 2.3 stroker has a rod ratio of 1.5.

Using longer rods with higher ratios does a couple things:

1. Transfers less force into side loading which equals:
   • less friction,
   • less heat,
   • less egging of the cylinder bores,
   • less stress on the piston's wrist pin.
2. Increases the TDC and BDC dwell time of the piston, which can:
   • increase Mass Fraction Burned,
   • lower pumping losses from high ignition advance angles,
   • is more forgiving of incorrect ignition advance
   • reduces stresses on the con rod and it's cap bolts in tension at TDC on the exhaust stroke

 

[rlacasse1]

Yes Sir!
Only thing that sucks is the $1300 price tag of the 94mm Billet Manley crankshaft.

I could go with a 94mm Eagle crankshaft, but why even mess with Eagle when Manley makes a much better product that is lighter, has much better oiling, is nitrided and knife edged.

I would love to run 159mm rods, but since I have the 156mm Pauters I'll rock them.

Plus the wrist pin only needs to be moved up 3mm instead of 6mm when using 156mm rods.

This will keep the wrist pin out of the oil ring groove so there will be much better oil ring control at higher rpms.
I already have a head that can handle 11k rpms...

Question about this.

Do you know of any bridges or machine shops that could pull that off? Some of the american muscle guys have bridges for pistons that have the wrist pin interfering with the rings.

They put the wrist pin in, and then a small piece is put in place that pretty much completes the ringland.

Another question. When you say move the wrist pin up 6mm for the 156 mm rod you meant with the 159mm rod right? With the 156mm rod you only move it 3mm right? And with a 159mm rod you would only have a 29mm compression height piston?

So basically:

156mm rod - wrist pin moved 3mm - 32mm compression height

159mm rod - wrist pin moved 6mm - 29mm compression height

 

[Strm Trpr]

Question about this.

Do you know of any bridges or machine shops that could pull that off? Some of the american muscle guys have bridges for pistons that have the wrist pin interfering with the rings.

They put the wrist pin in, and then a small piece is put in place that pretty much completes the ringland.
Another question. When you say move the wrist pin up 6mm for the 156 mm rod you meant with the 159mm rod right? With the 156mm rod you only move it 3mm right? And with a 159mm rod you would only have a 29mm compression height piston?

So basically:

156mm rod - wrist pin moved 3mm - 32mm compression height

159mm rod - wrist pin moved 6mm - 29mm compression height

Yes Sir, but those compression heights and rod lengths only work in a 4G64 block with a 94mm stroke crankshaft!

Not sure what you're asking about your machining question.

Typical 2.3L pistons have a 28.7mm compression height, 0.3mm deck clearance, 100mm stroke and 150mm rods.

The wrist pin is typically into the oil ring, and they come from the piston manufacturers like that.

 

[rlacasse1]

Yes Sir, but those compression heights and rod lengths only work in a 4G64 block with a 94mm stroke crankshaft!

Not sure what you're asking about your machining question.
Typical 2.3L pistons have a 28.7mm compression height, 0.3mm deck clearance, 100mm stroke and 150mm rods.

The wrist pin is typically into the oil ring, and they come from the piston manufacturers like that.

I'll add a link later that might explain it better as long as I can find it. But it's talked about on v8 engines.

But, what it is, from my understanding, is where the ring crossed the wrist pin hole, they make a insert. The insert is there to help keep the ring in place and not be unstable in that area.

Ok read the third full paragraph. So it's the paragraph that is right under the picture of the two pistons side by side. It talks about a rail that supports the ring.

http://www.strokerengine.com/RodStroke.html

 

[Strm Trpr]

Cool site.

Jackson Racing use Venolia Pistons in their high end engine builds.
I found this pic of an Evo 2.3L Venolia Piston.
They use Teflon Pin Buttons that have a flat for supporting the oil ring.

 

[gyd23]

So what kind of RPM range, torque, rod ratio, and reliability would a G4CS block bored .040 over (87.5mm) with 100mm crankshaft, 150mm rods, and Wiseco stroker pistons give me?

(please do not think of me as dumb or reply with negative comments if this seems sort of on edge for a safe build... I for god knows what reason bought the car with this setup already done up about a month ago. Did a little wrenching on it myself, and dyno'd it at 328hp & 320lbs of torque on 19psi)

 

[delta448]

At your current power level or even a bit higher you should have a pretty reliable and streetable shortblock. That's pretty much just a forged 2.4L 6 bolt with an overbore.

It would displace 2405cc, have a rod ratio of 1.5, have slightly better rpm durability than a stock 2.4 due to the lighter and stronger rotating assembly, and depending on a plethora of other things would have a little less power/torque potential than a 2.3L 6 bolt only due to thinner cylinder walls.

But with that displacement it would spool a 16G like a 2.0L does a T25.

 

[1fastlaser]

I currently just blew up my G4CS that had 8 year old wiseco/eagle combo. It has seen a lot of street miles, a lot of 9k revving, revv limter 1-2 shifting. I converted the car over to another car/automatic because with the gt4294/5spd it was just taking out 3-4th evo gears like crazy. Surprisingly the last trans I had in the car was a bs first half of 91 trans with single syncro everything and it held it all. I pulled the trans apart and put a welded diff in it and that was it.

Pretty much when I got the motor apart, the nitrous killed the motor for the auto. The motor was never setup for spray so when I started using it the pistons to wall was too tight, and the rings were also. It finally burnt cylinder 3 up and lost all compression in it.

I got it apart, and the crank/bearings (acl race main/rod bearings) where all perfect, no issues. Rods where perfect. I had a crank issue a year after I built it 8 years ago...broke the last balancer. I got a fresh crank/ polished magnafluxed/ balanced, got new bearings and put it back together with the same rods/pistons/rings. It broke while normal driving so I got lucky.

Right now im in the process of building a new 2.4. It will be after a lot of research a eagle rod with arp aged 625+ rod bolts and a 9:5.1 piston which is looking like CP at this point. I am trying to run a spare virgin G4CS block I had laying around and hopefully run the 86.5 factory bore to save piston weight.

I couldnt justify going to a 2.0 with my setup. I like the torque of the 2.4

 

[gyd23]

At your current power level or even a bit higher you should have a pretty reliable and streetable shortblock. That's pretty much just a forged 2.4L 6 bolt with an overbore.

It would displace 2405cc, have a rod ratio of 1.5, have slightly better rpm durability than a stock 2.4 due to the lighter and stronger rotating assembly, and depending on a plethora of other things would have a little less power/torque potential than a 2.3L 6 bolt only due to thinner cylinder walls.

But with that displacement it would spool a 16G like a 2.0L does a T25.

sweet.. why i don't know but the guy i bought the car from (who knows more than i do about these cars) told me it was stroked, he was right about it being built for torque and fast spool but however is not stroked.. since the crank that is in it is a forged 100mm crank and that's factory sized, i don't get why he thinks its stroked.
thanks for the answer though that helped my understanding of this build a lot more.

But i tell you what though compared to my friends 2.0 with a 16g on 25lbs the 87.5MM 2.4 spools my scm61 P-trim turbo like it's freaking nothing! i can be cruising in 5th gear at 70mph - punch it and as soon as it catches boost i can't even blink without it getting to full boost, probably a second or so. (i'm talking ZERO turbo-lag). I'm loving the torque and spool times, just not the reliability and simplicity of it. because it is definitely not simple and easy for me to efficiently tune, compared to a built 2.0 or even a 2.3.

Heck if your G4CS lasted that long i should get some miles out of this thing, i hardly ever beat on it and once i tune it for meth or race gas/91 mix it will rarely see 30 lbs.

...Should i be ok re-using my ARP head studs for the 3rd time in 600 miles?
(hint: the engine seen a water temp of 244 degrees the last time i drove it the day after i got it tuned, so i am assuming i warped the head and blew the head gasket. therefore i am going to replace it next time i see the car.
Which leads me to another question, would i be okay with just milling the head (if i can) and using a composite head gasket?