My 2jzge Build

[rturbo 930]

I was also shocked when I saw how hybridmotorsports(above yellow pic) did their motor mount. I was a bit concern about it failing on them but then when I really think about it, all the power is delivered out the back, not the sides of the engine, since the side mounts just holds it from rocking side to side. I would think the rear end and the tranny mount will take most of the beating. But I went ahead and over killed my mount anyways.

Rear end for sure, but I don't think the tranny mount does. At least I hope not, because I've seen what I consider to be some pretty damn pathetic tranny mounts installed in these cars.

 

Also, as far as I know (which may be wrong), the engine does put a twisting force on those mounts. I don't recall which it is, but it pushes up on one mount and down on the other, which could end up twisting the frame rails, which is why it's common to see a cross member like John C sells. Or at least that's what I've gathered, someone else can confirm/deny that.

[19762802+2]

Another thing to think about is that the Straight six is a pretty well balanced motor compared to a V8 and the mounts should be just fine when idling/normal driving. During a hard launch is a different story though the power is delivered out the back of the car but the engine and drivetrain do twist during a hard launch just watch a video of a drag race where you can see the engine, the engines move a lot and some guys with high HP numbers twist the frame of the entire car. Just think of Newtons third law of motion for every reaction there is an equal and opposite reaction, When the internals of the engine spin they are going to cause the engine itself to turn in the opposite direction, Like standing on a platform that spins and trying to swing a bat, You will spin in the opposite direction that you swing.

 

You may not have problems if you use rubber mounts and they are as solid as you suggest but if your going for a solid mount, it might not stand up to the forces it has to endure over time. I love what your doing though, I plan on just going NA 2jz or 1.5jz (1jz block with 2jz head) down the road, I can't wait to see how your Z turns out and I hope everything holds together for you as well.

Edited December 9, 2010 by 19762802+2

[Livin9it2up1]

I was also shocked when I saw how hybridmotorsports(above yellow pic) did their motor mount. I was a bit concern about it failing on them but then when I really think about it, all the power is delivered out the back, not the sides of the engine, since the side mounts just holds it from rocking side to side. I would think the rear end and the tranny mount will take most of the beating. But I went ahead and over killed my mount anyways.

 

 

Thankyou! finally someone who has some faith. Hybridmorotsports bought the car with a 2jz already installed and he basically redid the entire swap along with most of the car. I have personally ridden in that car and it is extremely fast, and felt very smooth.

[Livin9it2up1]

Another thing to think about is that the Straight six is a pretty well balanced motor compared to a V8 and the mounts should be just fine when idling/normal driving. During a hard launch is a different story though the power is delivered out the back of the car but the engine and drivetrain do twist during a hard launch just watch a video of a drag race where you can see the engine, the engines move a lot and some guys with high HP numbers twist the frame of the entire car. Just think of Newtons third law of motion for every reaction there is an equal and opposite reaction, When the internals of the engine spin they are going to cause the engine itself to turn in the opposite direction, Like standing on a platform that spins and trying to swing a bat, You will spin in the opposite direction that you swing.

 

You may not have problems if you use rubber mounts and they are as solid as you suggest but if your going for a solid mount, it might not stand up to the forces it has to endure over time. I love what your doing though, I plan on just going NA 2jz or 1.5jz (1jz block with 2jz head) down the road, I can't wait to see how your Z turns out and I hope everything holds together for you as well.

 

 

Thankyou i appreciate the science lesson as well! i havent seen that stuff in years. I am using rubber insulators that i pick out of a NAPA catalog and they seem to be working great! So the engine itself has some cushion, I have driven the car already and it feels really smooth and quite quick even being N/A

[ShaggyZ]

I was also shocked when I saw how hybridmotorsports(above yellow pic) did their motor mount. I was a bit concern about it failing on them but then when I really think about it, all the power is delivered out the back, not the sides of the engine, since the side mounts just holds it from rocking side to side. I would think the rear end and the tranny mount will take most of the beating. But I went ahead and over killed my mount anyways.

Have you ever revved an engine with the hood open and seen the engine twist one way? Imagine how much more twisting force there is when more than the engine's own weight (including the clutch and flywheel) resisting the increase in engine speed. I think the tranny mount does very little to resist the twisting.

[Livin9it2up1]

Have you ever revved an engine with the hood open and seen the engine twist one way? Imagine how much more twisting force there is when more than the engine's own weight (including the clutch and flywheel) resisting the increase in engine speed. I think the tranny mount does very little to resist the twisting.

 

I do agree with you i think the engine mounts are the what keeps the engine from twisting, so they would see most of the torque, aside from the rear end.

[piston]

I have seen a good amount of cars on the dyno 3 ft away and strap down dyno myself some pretty decent hp rwd vehicles. I know it toss and wants to turn per shift and wot. Just very curious on how much force and stress the mounts itself is actually taking being said the inline 6 is a pretty balanced motor. But I get the picture. The factory mount is not a straight bolt through the rubber instead it is two bolt/stud design molded into the rubber for better cushion so the rubber itself, cushions the pull on wot or first response. Meaning with a straight bolt through a plain rubber mount like some have used or like above, it will definitely pull and put most of the stress on the fabricated mounts itself on full boost or WOT since the cushion is no longer there. I hope this makes sense because I can't find the exact words to explain it.

 

#1. Think about it like this. two individual bolts, one bolt glued to the other by the rubber(middle section), when pulled on 1st bolt, the rubber absorbs the pull so 2nd bolt wont take a direct yank.

 

#2. Now with a straight through bolt(single), with rubber in the middle surrounding bolt, your fab mount takes a direct yank when engine jumps because your engine brackets are bolted directly to your fabricated mounts that are welded to the frame. Chances are your frame is not going to bend first, but your fabricated mount will if they are not strong enough.

 

I'm in your boat though Livin9it2up1. I agree that it is a budget build and it's all an experience. I don't see a problem with it being n/a and just cruising around, however stomping on it with boost in future is a bit risky. I shouldn't even be talking since mine is not even running yet. lol here's what mine ended up looking like after being chewed up by plenty on here.

[piston]

By the way, the markings on the cross member and steering rack in the center of the first pic is where the center of the original crank bolt is lined up. It is however offset towards passenger between 5/8" and 3/4" inch and that's the location of the 2jz crank bolt. Everyone has different point of views on the Z chassis. Some say the way you have it, it will flex the frame. Others say, no it wont because it is only about 5-7 inches away from the factory cross member which ties them together for strength which does kinda make sense too. IMO, you better be laying down some hardcore HP's because every car I heard twisting frames lays down high HP's. I'm really curious is there even a thread regarding a Datsun Z with twisted front fame rails besides failing due to rust issues?

Edited December 11, 2010 by piston

[Livin9it2up1]

I have seen a good amount of cars on the dyno 3 ft away and strap down dyno myself some pretty decent hp rwd vehicles. I know it toss and wants to turn per shift and wot. Just very curious on how much force and stress the mounts itself is actually taking being said the inline 6 is a pretty balanced motor. But I get the picture. The factory mount is not a straight bolt through the rubber instead it is two bolt/stud design molded into the rubber for better cushion so the rubber itself, cushions the pull on wot or first response. Meaning with a straight bolt through a plain rubber mount like some have used or like above, it will definitely pull and put most of the stress on the fabricated mounts itself on full boost or WOT since the cushion is no longer there. I hope this makes sense because I can't find the exact words to explain it.

 

#1. Think about it like this. two individual bolts, one bolt glued to the other by the rubber(middle section), when pulled on 1st bolt, the rubber absorbs the pull so 2nd bolt wont take a direct yank.

 

#2. Now with a straight through bolt(single), with rubber in the middle surrounding bolt, your fab mount takes a direct yank when engine jumps because your engine brackets are bolted directly to your fabricated mounts that are welded to the frame. Chances are your frame is not going to bend first, but your fabricated mount will if they are not strong enough.

 

I'm in your boat though Livin9it2up1. I agree that it is a budget build and it's all an experience. I don't see a problem with it being n/a and just cruising around, however stomping on it with boost in future is a bit risky. I shouldn't even be talking since mine is not even running yet. lol here's what mine ended up looking like after being chewed up by plenty on here.

 

 

By the way, the markings on the cross member and steering rack in the center of the first pic is where the center of the original crank bolt is lined up. It is however offset towards passenger between 5/8" and 3/4" inch and that's the location of the 2jz crank bolt. Everyone has different point of views on the Z chassis. Some say the way you have it, it will flex the frame. Others say, no it wont because it is only about 5-7 inches away from the factory cross member which ties them together for strength which does kinda make sense too. IMO, you better be laying down some hardcore HP's because every car I heard twisting frames lays down high HP's. I'm really curious is there even a thread regarding a Datsun Z with twisted front fame rails besides failing due to rust issues?

 

 

 

Every word what you said made perfect sense to me, i love the way your mounts came out, i have reconsidered my mounts and have defiantly decided to reinforce them quite a bit, I am not worried about twisting the frame due to the fact that my original cross member is only 8 or less inches away, I am trying to decide what approach I am going to take to reinforcing them. I made sure to get the "#2. Now with a straight through bolt(single), with rubber in the middle surrounding bolt" mounts due to the fact of iv seen many of the glued type rip apart from hard launching and that just seems id be asking for mount failure trying to use mounts like that.

[ShaggyZ]

The I6 being a "balanced" motor has nothing to do with the twisting forces.

[Livin9it2up1]

The I6 being a "balanced" motor has nothing to do with the twisting forces.

 

agreed

[ShaggyZ]

agreed

 

You just told piston "every word you said makes perfect sense to me." That's the second time two opposing thoughts have been posed and you agree completely with both.

[piston]

The I6 being a "balanced" motor has nothing to do with the twisting forces.

 

What I'm saying is that a v motor has 2 banks with pistons moving in different directions away from each other as to inline is centered, only moving up and down. No left right left right going on here, more balanced, less movement.

 

IMO, vehicle weight transfer is the most common cause of twisting forces especially in these uni body chassis.

[19762802+2]

What I'm saying is that a v motor has 2 banks with pistons moving in different directions away from each other as to inline is centered, only moving up and down. No left right left right going on here, more balanced, less movement.

 

IMO, vehicle weight transfer is the most common cause of twisting forces especially in these uni body chassis.

 

 

I agree at idle there is a difference in the forces on the frame between a L6 and a V8, If you have ever watched either one idling you can see the difference. I'm not totally sure if that is the case during a hard launch or at speed. I haven't dealt with V8's enough to know for sure but I'm guessing that it still transfers a lot of force to one side only during a hard launch. Hopefully one of the more experienced car guys will chime in.

[gtikyle]

It's very basic engineering...

The torque the motor is producing is trying to drive the vehicle forward. There is resistance in several pieces of your drivetrain, including the clutch/flywheel, gearbox, rear end, and ultimately your tires are resisting the forward motion of movement your engine is trying to produce. As the engines torque is resisted by these forces, a "moment" (see below) is created about the line of action of the force, the crank. This moment is resisted by the engine mounts. Imagine if the engine mounts were not there, and your wheels were cemented into the ground...Your engine would spin around itself.

 

It doesn't come down to "engine balance" so much as it does the torque from the motor, and the resistance it has to overcome to finally create acceleration of the body. While engine balance does play SOME into the need for good mounting, it's more about the power output of the engine, and the weight.

 

http://en.wikipedia.org/wiki/Torque

[piston]

"While engine balance does play SOME into the need for good mounting, it's more about the power output of the engine, and the weight."

 

correct...