G4CS (150mm)Short vs (156mm)Long Rods

[Whiteshadow]

I am in the process of building a G4CS block(2.4L 6 bolt). I have been reading all night about rod ratios and piston speeds yada yada and have not come up with anything that will cause me to go one way or another pretaining to long rods/short rods. According to some calculations, along with other threads...

RATIOS:
stock 4g63 2.0: (150mm)/(88mm)=1.7045

G4CS 2.4 w/4G63 Rods: (150mm)/(100mm)= 1.500** <---**Same as a Stroked 4G63 I believe**

G4CS 2.4 w/156mm Long Rods: (156mm)/(100mm)= 1.56

Here are my questions:

1) Will that .06 make THAT much of a difference in terms of prolonging engine life? Is it worth the extra money?
2) Who offers the long rods (Ive only found Magnu$ so far)
3) Will shifting at 7500rpms be safe for either option (Long/Short)


Basically my setup will end up being somewhere around the 600awhp range. So if i can get away with using 4g63 rods and forged pistons then i will. But if "Long Rods" are needed for that kind of power then i guess that'd be my only option.

What setups/power are you other 2.4L guys running and have you run into any complications. Any help would be appreciated. If i was unclear on anything just put it out there and elaborate some more.

 

[Street Surgeon]

Long rods are not required but will be helpful, if you want to shift at 7500 that should be no problem with either rod combo, however you might want to look in to the Kiggly brace and a set of grooved ACL bearings if you want to shift higher!

 

[Whiteshadow]

Yea the max I will ever shift at will be 8000 RPM's...I have read all over people shifting them higher...I mean unless your sustaining 8k revs (which i cant think of a situation where someone would) then your only going to be at that point for a second or two. Im wondering what will happen to the cylinder walls though over time and if they will get egg'd shaped (someone that's running a 2.4 please chime in if youve had any problems)

I guess my next question is, Will the long rod setup yield anymore displacement compared to the standard rod?...I doubt it could be anything too substantial. But with that kind of rod angle it always sits in the back of my head.

What will i benefit from by using the Kiggly Brace?

 

[Turbo Monk3y]

Yea the max I will ever shift at will be 8000 RPM's...I have read all over people shifting them higher...I mean unless your sustaining 8k revs (which i cant think of a situation where someone would) then your only going to be at that point for a second or two. Im wondering what will happen to the cylinder walls though over time and if they will get egg'd shaped (someone that's running a 2.4 please chime in if youve had any problems)

I guess my next question is, Will the long rod setup yield anymore displacement compared to the standard rod?...I doubt it could be anything too substantial. But with that kind of rod angle it always sits in the back of my head.

What will i benefit from by using the Kiggly Brace?

Kiggly did a test on 8500rpms and up and found out the Main caps were moving causing premature bearing wear... The kiggly brace was designed to combat this and seems to keep the mains in place when taking it above 8500rpms....

My question was, and still is... Can I use the Kiggly brace with Longer Bolts rather than using ARP main studs because I do not want to have a line hone done as my block has already been to the machine shop..... I have the G4CS block and The mains are like 25% more Beefier than the 4g63 ones only they are not bridged... ANYONE????

 

[Whiteshadow]

which rod setup are you running?...ive read a few places that some need clearencing. I was just going to buy the Piston/Rod combo from slowboy, the eagle and wiseco's. Hopefully those will hold up to 600whp. Looks like ill add the ol Kiggly brace then...

Another question, what are peaking using in terms of the crank pulley, stock or something else?

 

[Street Surgeon]

Kiggly did a test on 8500rpms and up and found out the Main caps were moving causing premature bearing wear... The kiggly brace was designed to combat this and seems to keep the mains in place when taking it above 8500rpms....

My question was, and still is... Can I use the Kiggly brace with Longer Bolts rather than using ARP main studs because I do not want to have a line hone done as my block has already been to the machine shop..... I have the G4CS block and The mains are like 25% more Beefier than the 4g63 ones only they are not bridged... ANYONE????

Email Kevin (kiggly), he told me if your block is line-honed to not put on the brace as that will pull things out of spec. However, he also told me if the block has NOT been line honed you can put it on no problem. Just shoot him an email he's real friendly and answers promptly.

 

[kiggly]

My main girdle needs the ARP studs. It will not work with the OE bolts or some other similar bolt unless it has a really small head. The reason is the ARP nuts are about the smallest footprint fastener you will find, and they even require a little denting on the oil pan by the last main to clear with the main girdle.

As far as line honing goes - the bolt surfaces of the main caps need to be flush with each other or else the girdle may pull the bores out of round. If the block was line bored and all the caps had the same amount taken off, the main girdle can be used without worries. Pretty much, you have to be able to lay a flat edge across all the main caps when installed and verify they are all at the same height. OEM blocks are like this. Otherwise, it has to tweak the girdle to clamp it down and this can pull the bores a little out of round.

For the ARP studs, I've used them in several different blocks with no line hone. Just don't tighten them to huge levels and instead use near-stock torque. My last 3 builds were with the main girdle, ARP's, and no line hone (55ft-lb, so I even went above OE levels). I didn't see strange bearing wear in any of these.

Also for what its worth, main bearings are nowhere near as finicky as rod bearings.

If I missed any questions or you have any more, just ask.

Kevin

 

[JWoodley]

Here is some information I've gathered that I'll pass along:

A few points to consider.

1: A change in stroke length will have the biggest effect on piston speed.
2: Long rod motors are generally considered better for higher RPMs.
3: Short rod motors are generally considered better for lower RPM applications.
4: A longer rods will actually increase piston speed over a shorter rod for a given stroke length. This is because a longer rods increases the dwell time of the piston at both top dead center, and bottom dead center in terms of degrees of crankshaft rotation, therefore for a given stroke length, a longer rod has less time to travel the length of stroke, for a given RPM.


I would also suggest that you do as gixman suggests, and call someone in the business. Build a repore with them, and together determine what is best for your application.
-Big Woo

Partially right. Longer rods actually decrease instantaneous piston velocities (most notably right around TDC and BDC). The piston accelerates away from TDC for instance more slowly with a longer rod (for a given stroke length) than with a shorter rod. However, it's worthwhile to note that if you're talking about mean piston speeds, obviously rod length has no effect as long as the stroke stays the same. The dwell time increase you enjoy is a function of the fact that the piston accelerates away from TDC slower than with a short rod.

The main reason (IMO) to go with a long rod 2.4 is that a long rod design puts less stress on the pistons and bearings (reduced side loading due to reduced centerline angle). You are also runner lighter pistons, with the associated benefits.

If you're talking strictly numbers, a short rod motor is actually capable of generating more torque, due to the fact that it achieves a 90 deg. rod/crank angle in less time (as measured by crank degrees) with the piston higher in the bore.

However, when you're only talking about a rod length difference of about 4%, most of these differences are lost in the noise anyway. Real world testing has shown that the long rod 2.4 is more robust and capable of quite a bit more RPM with a better powerband.

Talk to Marco at Magnus, he's been doing this quite a bit longer than me and is who I would consider one of the most knowledgable builders of 4G strokers.
-TurboGarageTech

 

[Boost Junkie]

I'm trying to build a long rod G4CS, but am being severely delayed because I can't get the 156mm rods for it. If ANYONE has any suggestions for a source please let me know.

Marco can get them for $750, but his phone guy couldn't even tell me what brand or how long it'd take it to make them/have them made.

Oh, and I have one of Kiggly's girdles waiting to go in too... waiting on these impossible long rods.

 

[goodbye]

Just go with stock length rods, a 1.5 ratio is not that bad, especially for a motor under 8000rpm. I shift mine at 8500 with no problems.

 

[JWoodley]

I'm trying to build a long rod G4CS, but am being severely delayed because I can't get the 156mm rods for it. If ANYONE has any suggestions for a source please let me know.

Marco can get them for $750, but his phone guy couldn't even tell me what brand or how long it'd take it to make them/have them made.

Oh, and I have one of Kiggly's girdles waiting to go in too... waiting on these impossible long rods.

Get the specs for them and call around to a few trusted manufacturers and see what you can come up with.

BTW, I'm located in Northern AL. Keep me posted with your progress!

 

[Lunch_Box]

For anyone wanting 156mm rods in the future just call up Pauter, they were the company to first make them for Magnus and last time I talked to them they had 3 sets.

 

[GSX_Dan]

I've placed an order for the long rods with magnus and after 7 weeks(3 weeks quoted) and many unreturned phone calls I cancelled my order. Marco just doesn't seem like he wants to deal with the little guy.

 

[Whiteshadow]

yea i cant blame ya for being mad, thats why i just went with the standard rod length, the gains are negligible when going to the long rod anyway

 

[Lunch_Box]

I've placed an order for the long rods with magnus and after 7 weeks(3 weeks quoted) and many unreturned phone calls I cancelled my order. Marco just doesn't seem like he wants to deal with the little guy.

If you still want a set of rods call Pauter (they use to make the rods for Magnus, not sure if they still do) and order direct. When I talked to them last they had 4 or so set sitting on the shelf.

 

[JWoodley]

If you still want a set of rods call Pauter (they use to make the rods for Magnus, not sure if they still do) and order direct. When I talked to them last they had 4 or so set sitting on the shelf.

Price?

 

[Lunch_Box]

Price?

Not sure but I think it was around $780. Give them a call and find out.