2.1 stroker help

[Dsm8697]

Looking to do a 4g63 7 bolt stroker keeping the stock 88mm crank. Is this possible with 60 over wiseco pistons?

 

[RadDsm]

No, because you aren't actually increasing the stroke at all.
You aren't going to get a noticeable increase in displacement by just boring the motor.

 

[Dsm8697]

I didnt mean to call it a stroker I just want a 2.1 displacement without buying a different crank. People put 88mm 4g63 cranks in 4g64 blocks to get 2.1 with the stock 86.5 mm 4g64 pistons which would be 60 over for a 4g63 block. I know the 4g64 has a 6mm taller deck I dunno if that helps in displacement or not.

 

[RadDsm]

You could do that with a 4g64 block, stock 88mm crank, and a 156mm rod.

 

[Dsm8697]

But why couldnt you do that in a 4g63 block with 60 over Wiseco's?

 

[RadDsm]

I can't explain the mathematics because I'm not that smart/technical (but hopefully someone will be able to explain it), but increasing the bore size by 1.5mm doesn't add up to .1L of extra displacement.

 

[ckrell]

Its rounded up from 2.07L. The 2.1 setup(156MM rod) has a better rod ratio it takes more side load off of the piston and gives a littel more time at TDC and BDC. Its benifits are at high RPM (8000rpm+)

 

[Dsm8697]

So going 60 over would give me 2.07? Thats like a 100 rpm quiker spool on boost or something?

 

[H4G64T]

You could just put a 2.4L crank in and have a 2.3L engine.

If you want to do 2.1 do it with the 4G64 block and 4G63 crank with super long rods for a better rod angularity.

 

[Dsm8697]

Nope I wanna build a 98-99 7 bolt with an 88mm evo crank and just wanna couple hundred rpm quicker spool.

 

[dsmusmc]

Nope I wanna build a 98-99 7 bolt with an 88mm evo crank and just wanna couple hundred rpm quicker spool.

Then do 156mm rods with higher compression stroker pistons and you will have a similar ratio and torque of a 2.1 destroke.

 

[XiKeiyaZI]

A .060 bore is pushing it a bit on a 4G63 block, eh? I wouldn't recommend over .040 without a lot of prep/clearance/understanding of just how thin you're making those walls.

 

[RadDsm]

Nope I wanna build a 98-99 7 bolt with an 88mm evo crank and just wanna couple hundred rpm quicker spool.

Just want to make sure you know that all 7 bolt cranks are the same (1G, 2G, Evo).

 

[stuckwithgsx]

A little off topic maybe, but if you're wanting to bore that much then why not sleeve it? And run higher compression? Wouldn't spool times become quicker that way?

 

[dsmusmc]

Just want to make sure you know that all 7 bolt cranks are the same (1G, 2G, Evo).

They are but I believe the EVO crank is a few pounds lighter.

 

[RadDsm]

They are but I believe the EVO crank is a few pounds lighter.

They have the same part number as 1G/2G cranks, so I think their weight would be the same.

 

[dsmusmc]

They have the same part number as 1G/2G cranks, so I think their weight would be the same.

Just going off what Darren at FFWD quoted.

 

[H4G64T]

I doubt you are going to get "a couple hundred RPMs of faster spool."

I mean it's not perfect but let us do the math. A 2351cc 4G64 block swap will get you, on a great build 800 RPMs more of spool on a 16G.

So for the sake of fun, that is 2.26 (rounded) RPMs per 1cc increase (the 4G63 is actually 1997cc so the difference is 354cc). That 60 over is really going to be more lik 2070cc so that is a gain of 73, which would put you about 165 rpms faster spool. Like I said this isn't fully scientific, there are other details to keep in mind, but it is a starting point and the larger the turbo you get, the less of a benefit that spool increase becomes.

 

[Dsm8697]

Well I know all 7 bolts have the same crank. I wanted to build the 98-99 7 bolt because of the split thrust bearing design to reduce crank walk problems. Evo 8 cranks weigh 5 pounds lighter then the dsm cranks. And 60 isnt pushing it. Ive seen alot of people going 60 over and even seen a few cases of 80 over. I wanted to do 60 over with a evo crank and not sure about rods yet. The pistons will have a higher then stock comp ratio. Not sure on what im doing for the head besides hks 264 cams. Im looking for a winter project is all.

 

[Boostinsideways]

To get a drastic increase in spool, your going need to need more than the .07 litre increase you would see with a 60 over.

You would be better off sleaving it and running higher CR, especially if E-85 is available.

 

[H4G64T]

Uh, 60 over is pretty drastic. I mean, I have seen people shoot heroine between their toes, but it doesn't mean it is safe to do, or recommended even. You want to basically thin the cylinder walls, build an engine that will produce more heat, subject it to higher internal compression numbers all while introducing boost which is more likely to create a detonation scenario.

Yeah, that needs to be rethought.

 

[Dsm8697]

Um, isn't the 4g64 block and 4g63 block just about the same dimensions? Because the 4g64 is like having a 4g63 with 60 over stock and theres no problems with it. 60 is a big number but in reality it's only 1.5 mm. I wasn't looking for like a 1000 rpms difference in spool just a little something noticeable.

 

[BoredDSM]

Um, isn't the 4g64 block and 4g63 block just about the same dimensions? Because the 4g64 is like having a 4g63 with 60 over stock and theres no problems with it. 60 is a big number but in reality it's only 1.5 mm. I wasn't looking for like a 1000 rpms difference in spool just a little something noticeable.

No, the 4g64 like you stated earlier has a taller deck height that does increase displacement much more than boring would do. That is the reason for the 100mm crank for a longer stroke. By using a shorter crank in a 4g64 you are destroking it and decreasing displacement but increasing rod ratio.

Just to put into perspective a 4g64 has thin walls to begin with. Not many if any people go beyond .040 over on a 4g64 and even if they got .060 over on a 4g63 they do not do so without at least sonic testing the block.

If your looking for increased spool just use a 2.3 motor or for a higher revving motor just go with a 2.0 long rod. There is a reason why people do not over bore for the purpose of displacement on DSM's because it is not worth it with all the better options out there.

 

[Dsm8697]

I know its taller im just saying that it would end up with the 4g64 bore and I would some how detonate unless im running low octane gas and beating the piss out of it. Or is I jack the comp really high and could only use race gas. And getting e85 in Vermont is pretty hard. I would have to drive 3 hours to town in New York for it which is the closest e85 for me.

 

[BoredDSM]

By boring it over that much you are sacrificing durability for a slight if any notable increase in displacement. Keep in mind the bigger the piston, the heavier it is which will play its role in how long your bearings handle the abuse. It just doesn't make sense to do such a thing. To answer your question yes it is possible to go .060 over but in the end is it going to be worth it? Personally it doesn't even make sense to do such a thing but it isn't my car.