[The Scifi Guy]

Y'know, Charlie is the #1 importer of 2.4 stuff and has extra 2.4 stuff, why not contact him? I know he has extra pistons and rods.

He has also made a SUPER torquey variant using a 2.3 diesel crank with custom rods and pistons that you might want to look into.

 

[GThound]

Look. All this stroker talk just needs to stop!!
Every time I start reading about them, out comes the calculator and I start searching the internet for pistons and rods... madness I tell you pure madness..

It is pure madness! The kind that should make me smile when I stomp the pedal. I am going to change the name of this thread to torque monster.

 

[GThound]

Are the 2.4L rods forged? I have a set of stock rods and pistons that I won’t be needing.

According to Bob…”Euro 2.4 liter engines have 134 mm forged rods with floating pins (22 mm)”

So, those should be forged rods. Could you send a picture? That might just work for me. It would be a little higher rod ratio vs using the stock 1.9 rods with 0.25” offset crank, which should help reduce tendency (so I have heard) for wonky cylinder wall and piston wear. I am not sure if I could use the pistons (pin height and piston diameter questions). Let me ponder and kick that around a bit in the spreadsheet.

Thank you reaching out and for the offer!

 

[GThound]

Y'know, Charlie is the #1 importer of 2.4 stuff and has extra 2.4 stuff, why not contact him? I know he has extra pistons and rods.

He has also made a SUPER torquey variant using a 2.3 diesel crank with custom rods and pistons that you might want to look into.

Thank you for the idea. Maybe someday on a 2.4 block / head. Right now I am going for more of a budget build and would like to leverage assets in hand (1.9 liter low port head multi-port modernized fuel injection system that is running so well).

I had not pondered the idea of using the 2.4 stock rods until now. More thinking and planning to do which admittedly can get tricky with some parts out of production for decades.

 

[Autoholic]

He has also made a SUPER torquey variant using a 2.3 diesel crank with custom rods and pistons that you might want to look into.

Unfortunately Charles no longer has any of these kits available.

 

[jmbinjax]

Not sure of your budget, or if you've done this already, what about German ebay?

 

[Autoholic]

According to Bob…”Euro 2.4 liter engines have 134 mm forged rods with floating pins (22 mm)”

So, those should be forged rods. Could you send a picture? That might just work for me. It would be a little higher rod ratio vs using the stock 1.9 rods with 0.25” offset crank, which should help reduce tendency (so I have heard) for wonky cylinder wall and piston wear. I am not sure if I could use the pistons (pin height and piston diameter questions). Let me ponder and kick that around a bit in the spreadsheet.

Thank you reaching out and for the offer!

I can send a pic tonight. I haven't separated the pistons and rods yet, but I could do that. You are planning on custom pistons anyways, so the 2.4L rods should still work.

 

[RallyBob]

Are the 2.4L rods forged? I have a set of stock rods and pistons that I won’t be needing.

Yes, forged, 134 mm long, and bronze-bushed for 22 mm floating pins.

 

[GThound]

Not sure of your budget, or if you've done this already, what about German ebay?
View attachment 454175

Thanks for the idea and another option. I had not considered it. There seem to be quite a few options on the table at the $400+ price point for rods ranging from Opel to VW G60 to Eagle Neon and other even pricier options.

 

[GThound]

I got a little more data tonight, specifically the combustion chamber volume.

Here is what I did:

1. I flipped over the head so the combustion chamber was facing up
2. I screwed in an old spark plug to close the hole.
3. I filled a big 100 ML syringe with water, put it on the gram scale and zeroed the scale
4. I filled up the cylinder head with water to the brim and then weighed the syringe and wrote down the weight
5. Then extracted the water with the syringe, dried out the combustion chamber with paper towel and repeated for all cylinders

The photo below shows a combustion chamber filled with water. It was a bit tricky with the meniscus.

I had an average of 53 cc (I had previously estimated 55 cc) volume per cylinder combustion chamber. This tightens up the error bars on my compression ratio calculations. I believe it is coming in at something like 10.3:1 now. I will fine tune the numbers even more once I have the finished crank and deck height measurements as well as piston top recess volume.

 

[Autoholic]

You can use a clear piece of lexan with a hole drilled in it to fill it with water. No problem with meniscus, less error in the volume.

 

[Vincent]

You can use a clear piece of lexan with a hole drilled in it to fill it with water. No problem with meniscus, less error in the volume.

X2

Best to use the lexan trick to get more accurate measurments

 

[GThound]

You can use a clear piece of lexan with a hole drilled in it to fill it with water. No problem with meniscus, less error in the volume.

Thanks gentlemen. Glad to learn from the voice of experience. That totally makes sense now that you say it. I had just not done this before or thought of it before. Thanks for solving my meniscus woes. I will give this a try and get better numbers today.

 

[Autoholic]

Get the thicker Lexan for this.

Falken Design 12 in. x 12 in. x 1/4 in. Thick Acrylic Clear Sheet Falken Design ACRYLIC-CL-1-4/1212 - The Home Depot

Falken Design Acrylic has many benefiting characteristics like glossy surface, weather resistance, sturdy, durable, light weight, thermoplastic and innovative. Acrylic is lighter and stronger alternative

www.homedepot.com

 

[GThound]

I found a piece of lexan at home and made a quick cover with an hole in it and sealed it to the cylinder head with aquaphor.

Here is the other half of the measuring apparatus.

I got more consistent volumes with this approach. And I have an average of 52.4cc to add to the compression ratio spreadsheet.

Cylinder 1: 52 cc
Cylinder 2: 53 cc
Cylinder 3: 52.6 cc
Cylinder 4: 52 cc

Plus it is extra fun doing this with my sons, learning about engines, scientific method.

 

[GThound]

So here is where my thinking is starting to land regarding my engine geometry rod ratio for the torque monster. I want maximum torque (low rod ratio), but still decent revving (sports car rather than truck like) and good reliability (engine life).

If a stock crankshaft stroke is roughly 2.75” ~ 70 mm and stock rods are roughly 128 mm long. Then a stock rod ratio would be 128 / 70 = 1.82. Does that sound right?

If I get my crank welded and offset ground by 0.25”, the new stroke would be roughly 3.25” ~ 82.5 mm. Although this stroke is 0.5” longer than a 1.9L, it would still be shorter than the 85mm stroke of the factory Opel 2.4 engines. So, hopefully I can achieve a little higher revving if I can move enough air for it to breathe at higher RPMs. I calculate the rod ratio with the stroker crank and stock rods at 128 / 82.5 = 1.55. This would be great for torque, but concerns me about the piston and cylinder wear from the side forces. So, I would like to get rod ratio above 1.6.

If I use the eagle rods for the dodge neon they are 5.472” which is 139 mm for a rod ratio of 139 / 82.5 = 1.68. Better on the rod ratio. A few downsides are 1) price @ $400, 2) not quite as torquey, 3) shorter compression height (short pistons).

If I use the original 2.4 forged rods, mentioned a few entries back…

forged, 134 mm long, and bronze-bushed for 22 mm floating pins.

In a 1.9 block with the welded and offset ground crank, I would have a rod ratio of 134 / 82.5 = 1.62. That is the current plan. As it maximizes the torque but get rod ratio in the safer > 1.6 rod ratio realm. Plus, this gives me a larger pin height for better ring separation and larger piston skirt for less wiggling / rocking in the bore.

Your rod to stroke ratio is also something you need to pay attention to as mentioned above. If too low, you will also accelerate the cylinder wear. I was able to use off the shelf 97mm Buick V6 pistons (cheap!), VW G60 136mm rods and put together a combination that yielded 2.6L displacement.

This is another cool option, and one I contemplated. The VW rods would give me a rod ratio of 136 / 82.5 = 1.65. I like that number.

But since this is a torque monster budget build, I am going to go with the 134 mm forged opel rods that yield the 1.62 rod ratio. I will send pics of those one they arrive in the mail (thanks Autoholic) and I start the rod refurbishment and balancing process.

 

[Autoholic]

Cylinder and piston wear is going to be one of those topics that takes a lot of variables into account. Your rod ratio is only going to be a component of that. How long your piston skirts are also matters, the piston rings, and your oil just to mention a few other considerations. I think it's important to remember that the vast majority of engine wear happens when the engine is cold. You could have two identical engines that are treated very differently with respect to maintenance and how they were operated over a span of 50,000 miles, resulting in very different amounts of engine wear.

You're building an engine for the street, I'd focus more on torque than high RPMs.

 

[guyopel]

Most of the piston, rings and cylinder wall wear is because of increased piston speed with using the longer stroke. Opel pistons are 30 Degs. off-set. in stock form.
You could off-set bore your block to slow piston wear and control trust.
2.2 and 2.4 piston rings are thinner than 1.9 pistons so 2.2 & 2.4 rings should not wear any faster.

 

[Commodåren]

Cylinder and piston wear is going to be one of those topics that takes a lot of variables into account. Your rod ratio is only going to be a component of that. How long your piston skirts are also matters, the piston rings, and your oil just to mention a few other considerations. I think it's important to remember that the vast majority of engine wear happens when the engine is cold. You could have two identical engines that are treated very differently with respect to maintenance and how they were operated over a span of 50,000 miles, resulting in very different amounts of engine wear.

You're building an engine for the street, I'd focus more on torque than high RPMs.

Concentrate on low and mid range torque with a power peak below 5500-6000 RPM, and the rod ratio shouldn't matter much anymore.

 

[Piver]

Most of the piston, rings and cylinder wall wear is because of increased piston speed with using the longer stroke. Opel pistons are 30 Degs. off-set. in stock form.
You could off-set bore your block to slow piston wear and control trust.
2.2 and 2.4 piston rings are thinner than 1.9 pistons so 2.2 & 2.4 rings should not wear any faster.

Hello,
the easiest way and without too much hassle is to mount Wiseco CIH 2.4 pistons, height of 31.15 and diameter 96 (4 Wiseco ASC-07351 Opel Custom 1.020 X 3.8380 Forged Performance Pistons) with Toyota connecting rods length 138mm x55mmx22mm only the width is to be reduced ( Connecting Rods for Toyota Camry MR2 Celica GT SX 5SFE 5S-FE 2.2L ) on a 2.2 cih
;-)