2G Rod style, Piston clearance, 2g block, 1g rod, 2JZ-GE piston

[RSS]

Hi there,
I'm trying to build a 2g 7 bolt engine using 1g 6 bolt connecting rod (which a lot of people say that they are stronger than 2g 7 bolt rods) and I got 2JZ-GE pistons with 86 mm bore and 22 mm pin, These pistons are full floating. I know that the rod surface needs to be machined and it’s ok. Also the rod pin end will be bored to accept 22 mm pin.
all machining is free for me. I need professional advices for following problems.

# Piston to cylinder clearance:
Both 4g63 and 2jz-ge blocks are cast iron, 4g63 workshop manual says 0.02 mm to 0.04 mm for piston to wall clearance. However, 2JZ-GE workshop manual mentioned clearance is 0.073 mm to 0.096 mm. What should be 2jz piston to 4g63 cylinder wall clearance?
What about piston rings end gap?

# Rod and pin style, which one is better and why? I also need diameters and clearance in each case.
1. Press fit:
1g rod pin end should be bored to press fit 22 mm pin, what should be exact diameter of rod pin end?

2. Floating pin without bushing:
Some people say that it could be a floating pin without bushing in the rod pin end, is this ok? If yes, what would be the clearance?

3. Floating pin with bushing
In this case pin end needs to be bored little more than previous cases. Does this excessive pin end boring make it weak and more likely to rod failure? Note that these rods are made to work with 21 mm press fitted pin. If this case is ok what clearance needed for accept bushing and floating pin.

My engine target power is 250 whp and max RPM would be around 6500. These parts are all I got and I have to use them.
Regards,

 

[1990TSIAWDTALON]

Don't even bother with that mess if all you want is 250hp. Rebuild it stock and turn it 7500. Use 6 bolt rods if you want which are beefier than the 7 bolt. Put a E16g turbo on it and enjoy it.
Why in the world do you want to mix and try to match all of that stuff for a dismal 250 whp? The 4G63 can do over 300 with a bigger turbo than the stock unit. It is relatively easy to get 100 hp per hole out of these motors with very minimal upgrades such as a tuning platform, larger turbo and the supporting fuel upgrades needed. That would be SO much easier. Just sayin.

 

[Maximuscr31]

Stock internals will hold 350whp just fine without breaking a sweat

 

[RSS]

Don't even bother with that mess if all you want is 250hp. Rebuild it stock and turn it 7500. Use 6 bolt rods if you want which are beefier than the 7 bolt. Put a E16g turbo on it and enjoy it.
Why in the world do you want to mix and try to match all of that stuff for a dismal 250 whp? The 4G63 can do over 300 with a bigger turbo than the stock unit. It is relatively easy to get 100 hp per hole out of these motors with very minimal upgrades such as a tuning platform, larger turbo and the supporting fuel upgrades needed. That would be SO much easier. Just sayin.

thanks for your response, these parts are all thing I have and I should use them. In my country, It's difficult to find new and original parts.

 

[1990TSIAWDTALON]

I understand now. I am sorry and didn't realize you were not in the states. I build these little monsters over here. You can achieve over 250hp with the stock components very easy. Put a bigger turbo on, bigger fuel injectors and a way to tune it (I put the tuning part in FIRST because you will need it to control bigger fuel injectors and more boost)
Just for instance, I turn my 6 bolt highly modified 4g63 to over 9000 rpm and I am sure it is making over 400hp. It has a 60mm turbo and very big fuel injectors.
The answers to your questions are complex for the components but I normally build them with .006"-.0010" PTW clearance and solid .002" main bearing clearances with .0015-.003" rod bearing clearances.
I am trying to be helpful.
Manley has a good guide for the pin diameter HERE.
It looks like the answer to question #2 is .8671"
Manleys 21mm bushings are a part I have in stock and they measure .8945" OD. They are for replacement in a set of I beam rods I have. The 22mm bushings are also available and I am sure Manley could provide the dimensions if you can't find it on their website, but I would think that the OD would be the same.
Marty

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[dwb]

I seem to recall when researching 1g rods/2g pistons that the big end of the rods won't natively fit a 7 bolt crank. The width of the rod is too wide and would need machined. I don't know if the journals are the same size, so that's something to verify before you start.

This drawing was very helpful when I put 2g pistons on 1g rods:

You must be logged in to view this image or video.

 

[RSS]

The answers to your questions are complex for the components but I normally build them with .006"-.0010" PTW clearance and solid .002" main bearing clearances with .0015-.003" rod bearing clearances.

thanks a lot for your time and info. I got answer about bearing clearance. 0.001'' to 0.006'' PTW clearance is very wide range, It's about 0.025 mm to 0.152 mm, I'm very confused about this.

I seem to recall when researching 1g rods/2g pistons that the big end of the rods won't natively fit a 7 bolt crank. The width of the rod is too wide and would need machined. I don't know if the journals are the same size, so that's something to verify before you start.

This drawing was very helpful when I put 2g pistons on 1g rods:

You must be logged in to view this image or video.

This info is for press fitting pins, It's ok. what about using bushing for floating pin?!

 

[1990TSIAWDTALON]

thanks a lot for your time and info. I got answer about bearing clearance. 0.001'' to 0.006'' PTW clearance is very wide range, It's about 0.025 mm to 0.152 mm, I'm very confused about this.

It is my OWN specs as I build engines as my 2nd job currently. They are MY own clearance thresholds, not from a service manual. I don't know if I said anything about that so I'm sorry. I've built motors since 1978 or so so I don't go "by the book" on engine builds but they are a good "guide" if you are not familiar with what you are working with.

 

[RSS]

It is my OWN specs as I build engines as my 2nd job currently. They are MY own clearance thresholds, not from a service manual. I don't know if I said anything about that so I'm sorry. I've built motors since 1978 or so so I don't go "by the book" on engine builds but they are a good "guide" if you are not familiar with what you are working with.

No problem, I know what are you talking about. As you are an experienced engine builder, please let me know what's your idea about PTW for my specific engine

 

[bastarddsm]

stock 4g pistons are cast and wants 0.001-0.002" clearance. But I think I remember that 2jz stuff was forged from factory. So it might want a bit more clearance. I strongly doubt they would be 2618 as it's soft and would not last long enough for an oem application. 0.006" would be very wide clearance for even a 2618 forged piston at our bore sizes. I would think 0.002"-0.004" would be a good safe range, and that falls right into the range from your 2jz manual. Use what the 2jz manual says, which looks like 0.003"-.004". Make sure you check ring end gaps! Use the 2jz spec too!

For rods, we have a motor almost exactly like what you are trying to do. We narrowed up the rods, and bored the ends for 22mm pins. We do not use a bushing. We drilled the end of the rod for an oil hole, and run about 0.001" clearance. Seems to work out fine for us. You possibly could tighten up that clearance some.

IIRC the 2jz piston has a shorter compression height, are you planning on building a 2.3L motor with a 100mm stroke?

 

[1990TSIAWDTALON]

I will try my best to find a more specific PTW for you. You are not asking for alot of hi performance numbers so let me do some looking into it.
Ring gaps for my engines are pretty close to the piston manufacturer turbo/NOS applications.

 

[bastarddsm]

The answers to your questions are complex for the components but I normally build them with .006"-.0010" PTW clearance and solid .002" main bearing clearances with .0015-.003" rod bearing clearances.

please do not ever reccomend clearance specs to anyone. That's simply too much ptw for anyone but like boostin. and the rod clearances you spec are for someone running 50wt oil. It's not good for anything but a special case, and you didn't add any of that information in there.

 

[1990TSIAWDTALON]

We narrowed up the rods, and bored the ends for 22mm pins. We do not use a bushing. We drilled the end of the rod for an oil hole, and run about 0.001" clearance. Seems to work out fine for us. You possibly could tighten up some.

Is this where you drill your oiling holes Curt?
This is just a Manley I beam rod with bushings. The new bushing come with no holes so aligning is as easy as making that hole in the bushing. Glad to here that yours works without the bushing without issues.

You must be logged in to view this image or video.

 

[1990TSIAWDTALON]

please do not ever reccomend clearance specs to anyone. That's simply too much ptw for anyone but like boostin. and the rod clearances you spec are for someone running 50wt oil. It's not good for anything but a special case, and you didn't add any of that information in there.

Sure I'll remember that.
Disclaimer.......All of my engines are built for more than stock applications to my own specs.
My specs only work for me. Sorry to damage this thread.
Is that better? I sure hated to have to repeat what I already said IF YOU WOULD READ IT.
Now continue on fellows.

 

[bastarddsm]

Yes, that's exactly what we did, on an I beam type rod that's about the only place to do it - could maybe come in from the bottom at an angle, but idk may disrupt stress flow too much.

As for the other, it isn't exactly written as don't do this.... Say some impressionable kid had a set of 4032 pistons (mahle, srp) and did 0.010 clearance, the thing would be terrible! - or like in this case where the pistons are most likely cast or some other low expansion alloy, and the poster may not be fluent in english, nuances may be hard to pick up.

Actually I failed too, I should have asked the poster to show a picture of his pistons so we can see what they are - for all we know they could be a cheap casting that needs a tight clearance, or they could be some old trw like dinosaur deal that needs ton's..

No problem, I know what are you talking about. As you are an experienced engine builder, please let me know what's your idea about PTW for my specific engine

Post a picture of your rods and your pistons please.

 

[RSS]

stock 4g pistons are cast and wants 0.001-0.002" clearance. But I think I remember that 2jz stuff was forged from factory. So it might want a bit more clearance. I strongly doubt they would be 2618 as it's soft and would not last long enough for an oem application. 0.006" would be very wide clearance for even a 2618 forged piston at our bore sizes. I would think 0.002"-0.004" would be a good safe range, and that falls right into the range from your 2jz manual. Use what the 2jz manual says, which looks like 0.003"-.004". Make sure you check ring end gaps! Use the 2jz spec too!

For rods, we have a motor almost exactly like what you are trying to do. We narrowed up the rods, and bored the ends for 22mm pins. We do not use a bushing. We drilled the end of the rod for an oil hole, and run about 0.001" clearance. Seems to work out fine for us. You possibly could tighten up that clearance some.

IIRC the 2jz piston has a shorter compression height, are you planning on building a 2.3L motor with a 100mm stroke?

nice info. 2jz pistons are not forged, but they are heavier and I think they are die cast and more condensed relative to other oem pistons. I also think it's better idea to use 2jz workshop manual for piston clearance and ring end gap.
what about longevity of floating pin without bushing? I think it will cause scratches on both of pin and bushing.
2jz piston compression height is about 1 mm shorter than 4g63 piston, I would use thinner head gasket or deck block and head. It's cylinder head is sohc version.
I'm posting pictures of pistons and rod.

 

[bastarddsm]

It is fairly common to use a floating pin without a bushing. Many motorcycles are this way, I beleve some mopar v8's are that way. You really don't have much choice as a 6 bolt rod would be getting pretty thin if you installed a bushing imo. You could do it as a press fit...

 

[RSS]

I have built some Chevy 350, 305 and 250. This engine is my first 4 cylinder turbo full floating non-V8 engine.

I'm worry about converting full float to press fit, do you think it's not bad idea?

 

[1990TSIAWDTALON]

It can be done, as our other member said. After he mentioned motorcycles, I thought about it, and our small engine stuff (Predator 212cc go-cart motors) are that way. They don't run bushings and are full floating pins that see around 6500-7000 rpms with no ill effect. We pull the side covers on them and rotate the engine until we can see the wrist pin, then we work the retainer off of one side, slide out the pin and replace the stock rod with a billet aluminum rod for hi rpms. No failures there and we do run those engines hard.
If you have rebuilt those Chevy motors, you can do the 4g63. It is just a little different but still easy.
I was going to ask if you had access to a DOHC head? It would be a nice addition to the build instead of the SOHC head.

 

[RSS]

pictures

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[RSS]

I would search a little more about pins.
there is DOHC heads, but price is about my two month income!

 

[bastarddsm]

How about a picture of bottom of piston? That definately looks like it's a cast piston. The ptw specs you have, make sure that is not a service limit, and that it is new clearance! I think you will want to be on the tighter end of the clearance measurements, and break it in slow.

 

[RSS]

How about a picture of bottom of piston? That definately looks like it's a cast piston.

The ptw specs you have, make sure that is not a service limit, and that it is new clearance! I think you will want to be on the tighter end of the clearance measurements, and break it in slow.

You must be logged in to view this image or video.

any comments?

 

[1990TSIAWDTALON]

Have you checked you cylinder bores for size and then mic'd the pistons and done the math to determine your PTW clearance? That service manual is saying a maximum of .0047". I have ran with more but that should be the next thing for you to check and post back.

 

[bastarddsm]

2jz is 86mm bore iirc so he's gonna have to bore/hone. 0.0047 would be pretty loose for a cast piston imo.

OP have you thought about valve reliefs?