Long rod motors?

[Pushit2.0]

I just thought we should talk about this a little more. So what, if any, tested information do we have on this. I have 2 sets of Crower rods for my car, normal and 6mm longer rods. I was going to come up with a way to test the two sets, keeping as much the same as possible. With the longer rod you need to get custom pistons that moves the pin up in the piston, giving a better rod ratio and more dwell time at TDC. What do we think on this?

~John
I am running a 2.0 still also

[Pimpin Dsmstyle]

Ironically, I was just talking about this with someone last night. I was going to create a post but I didn't know what to say. I don't know much about it but I would like to.

If people could, could we have information added newb style? I want to be able to understand. good call John.

[JET]

The longer rods will give the rod a shallower angle. This reduces side load on the pistons, and as John stated, increases the dwell time. Dwell time is good in an NA application, you can make more power. In a FI engine with high boost, it is not desirable since we are fighting detonation and that gives more time for detonation to occur.

The rod ratio of the 2.4 is 1.5 and the long rod version is 1.56. 1.7 is considered ideal for a NA engine. I really don't see a big enough difference with the long rod version to warrant the extra cost. It is less than a 10% difference in rod ratio and there are some bad effects too.

[Shane@DBPerformance]

I am not sure why you would want a longer rod on a 2.0, unless you want to rev it like a motor cycle. It already has a 1.69 rod ratio, which is quite good. With that and the 88mm stroke, you should be able to rev to 9600 with off the shelf parts. Most of the guys reving higher than that are running aluminum rods.

[Jakey]

So what justification does Marco use for his long rod shortblocks?

[SlowWhite]

Also do you have to change anything on the motor as far as Oil goes? Talked with my brother about this for like 2 seconds and he mentioned that on his built MR2 Motor that he plans to rev the car to I think he said 8K (but anyrated point is) that he also mentioned he had to have something done to his oil pump in order to keep the flow of the oil up enough to handle the higher Revs? Or at least I think that's what he said. (again really quick conversation, didn't go into depth)...

Just thought that might be why guys like brent go with a Dry Sump system.

[JET]

Originally Posted by Jakey

So what justification does Marco use for his long rod shortblocks?

He's canadian?? He sells them saying you can rev them higher than a regular rod 2.4.

A dry sump system prevents foaming of the oil and also allows the engine to be mounted lower in the frame to lower the CG.

it also cuts parasitic drag since the crank doesn't have to plow through all that oil anymore

[CVD]

All what oil?

[Pushit2.0]

So for a turbo motor you want the rod ratio lower then a NA motor, so the piston is not at TDC as long. I planned on reving my motor as high as possible, a few things like power band, trap speed will help me deside how high I should go. 9600 might be high enough I do not know.

~John

[Shane@DBPerformance]

Brent got rid of his dry sump a long time ago due to crank problems. DSM oil pumps make too much oil pressure to begin with once you remove the balance shafts and they rarely fail, unlike on some cars like Hondas. So we don't have to worry too much about aftermarket oil pump gears and such, unless you want to do a dry sump system.

[Shane@DBPerformance]

Originally Posted by Pushit2.0

So for a turbo motor you want the rod ratio lower then a NA motor, so the piston is not at TDC as long.

No, it's just that the 2.0 rod ratio is good enough already. You never want a bad rod ratio, the question is just if the hype is worth all the extra effort. Especially, when it really doesn't help the piston speed problem on the 2.4l.

[JET]

Originally Posted by mastadonic

it also cuts parasitic drag since the crank doesn't have to plow through all that oil anymore

What the hell are you talking about?? The crank doesn't get changed at all, just the rods and pistons.

[1ViciousGSX]

Marco "claims" that in theory, based on the geometry, the rod ratio difference is worth about maybe 200-400 rpm more, but in practice it's worth alot more.

My main reason for going with the long rod version is not because it was the most expensive (althought some might think differently ), but because I wanted the "best of both worlds" so to speak. I wanted the longer stroke of the 2.4L for my heavy car, but I also wanted the ability to turn higher rpms with less chance of scuffing the pistons/cylinder walls that can happen on a high rev'ed 2.4L

[EclipseGST]

I'm not a fan of Marco or what he "claims"! Long rod motors seem overrated and so does dry sump oil pumps. Just my $.02~


Off topic: Welcome back Mike.

[FattyBoomBatty]

use some 2.6 rods with some really thick bearings.

[SlowWhite]

I wondered about the oil thing ever since my motor went. One of the things I changed was reving my car to 8200rpms regularily. Thought Oil starvation was one of the reasons my motor went? And didn't even think to wonder about oil until my brother mentioned it in his list of things he did to his motor.

Thanks for the info... What if you still have your balance shafts?

Anyone know how high Brent and Shep rev'd there 2.0's?

[JET]

I know Shep was shifting over 10k RPM, I saw his AEM log at the 2003 shootout. 8200 RPM wasn't a reason for your engine to die Brian. It may have quickened it, but it isn't the cause. 8200 RPM on a 2.0 is nothing. That is the redline I plan to run on my 2.4.

[Goat Blower]

I was just running 8500 rpms on the dyno last night, 124 miles on a 2.4, standard rod length. I've yet to see any actual data showing a regular 2.4 can't rev past a certain limit.

[Pushit2.0]

Brian you should be able to rev that motor to 9,000rpm if you want, but 8,500rpm is where I had my rev limit set to all last year.

~John