4.25 stroke too much? please help :)
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Staging Lane
Joined: Sep 2002
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From: Leonardtown, MD
4.25 stroke too much? please help :) Guy's I'm looking at a bunch of different options... I don't want the car to be a high reving 8500 rpm machine, i like torque <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Anyway would the Iron block 4.0 stock bore and a 4.25 stroke be a good idea? Or is the ratio of stroke/bore a bad idea etc. I was either looking to do that or a 4.125 stroke with a 4.035 bore. Also which would be better for a power adder/and overall life of the motor. I'm trying to find a happy medium here. I would hook the spray up bur rarely use it.
Thanks everyone
Anyway would the Iron block 4.0 stock bore and a 4.25 stroke be a good idea? Or is the ratio of stroke/bore a bad idea etc. I was either looking to do that or a 4.125 stroke with a 4.035 bore. Also which would be better for a power adder/and overall life of the motor. I'm trying to find a happy medium here. I would hook the spray up bur rarely use it.
Thanks everyone
TECH Apprentice
Joined: Aug 2002
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From: Gambrills, MD
Re: 4.25 stroke too much? please help :) Donovan, can you go that big on the stroke w/o going to a shorter rod? If not, you will have more side loading & resultant friction. Certainly the compression height of the pistons will have to be shorter.
Who are you looking at to build this motor --- ARE, SLP, MTI? I'm sure the builder can give you many insights into the pros & cons of various bore/stroke combos.
I'm old school, so I always preferred square-built engines. The LS1 is a different beast, though.
Who are you looking at to build this motor --- ARE, SLP, MTI? I'm sure the builder can give you many insights into the pros & cons of various bore/stroke combos.
I'm old school, so I always preferred square-built engines. The LS1 is a different beast, though.
TECH Senior Member
Joined: Nov 2001
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Re: 4.25 stroke too much? please help :) I think you are limited to a 4.125 stroke. I believe you cant get a rod for the 4.25 stroke and also the block will need significant clearancing if I remember correctly.
I would go with a 4.125 stroke and a 4.030 overbore (4.030 overbore to allow for a BIG shot of juice)
That with good heads/cam and studs/gaskets will be bulletproof <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Cheers,
Chris
I would go with a 4.125 stroke and a 4.030 overbore (4.030 overbore to allow for a BIG shot of juice)
That with good heads/cam and studs/gaskets will be bulletproof <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Cheers,
Chris
Re: 4.25 stroke too much? please help :) </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Chris ARE 360:
<strong>I would go with a 4.125 stroke and a 4.030 overbore (4.030 overbore to allow for a BIG shot of juice)
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Nine Ball recommended that one should go with a square or oversquare configuration than an undersquare one like 4.030 x 4.125. I would still like to know the disadvantages of going with an undersquare configuration.
<strong>I would go with a 4.125 stroke and a 4.030 overbore (4.030 overbore to allow for a BIG shot of juice)
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Nine Ball recommended that one should go with a square or oversquare configuration than an undersquare one like 4.030 x 4.125. I would still like to know the disadvantages of going with an undersquare configuration.
TECH Senior Member
Joined: Nov 2001
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From: Troy, AL
Re: 4.25 stroke too much? please help :) "I think you are limited to a 4.125 stroke. I believe you cant get a rod for the 4.25 stroke"
It's already been done. MTI did it with their 449 and I'm going to do it again with my 471.
The whole bore/stroke ratio thing is way overdone, IMO. Actually bore has nothing to do with it. It's ROD/stroke ratio that effects side loading and piston velocity. At the RPMs that we're generally turning in our little street/strip engine (generally less than 6800) I really don't see a little extra piston velocity or side loading of the pistons outweighing the benefits of the extra cubes afforded by a longer stroke. How long does an engine last with stock rod/stroke assuming that it's eventual death is caused by cylinder wear? 150,000 miles at least if not 200,000. How much difference could the extra side loading make? Are we only going to make 125,000 miles? 100,000? Maybe only 75,000 miles? I seriously doubt that it would make THAT much difference but even if it did, I would think that it would be acceptable to most folks building this kind of engine.
It's already been done. MTI did it with their 449 and I'm going to do it again with my 471.
The whole bore/stroke ratio thing is way overdone, IMO. Actually bore has nothing to do with it. It's ROD/stroke ratio that effects side loading and piston velocity. At the RPMs that we're generally turning in our little street/strip engine (generally less than 6800) I really don't see a little extra piston velocity or side loading of the pistons outweighing the benefits of the extra cubes afforded by a longer stroke. How long does an engine last with stock rod/stroke assuming that it's eventual death is caused by cylinder wear? 150,000 miles at least if not 200,000. How much difference could the extra side loading make? Are we only going to make 125,000 miles? 100,000? Maybe only 75,000 miles? I seriously doubt that it would make THAT much difference but even if it did, I would think that it would be acceptable to most folks building this kind of engine.
Re: 4.25 stroke too much? please help :) Thanks for the info Colonel <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> I think I will be doing the 4.060 x 4.125 option. This is much cheaper than resleeving a block.
New LQ4 block overbored to 4.060 with Lunati 4.125 crank: $600 + $350 + $2175 = $3125
New LQ4 block resleeved and overbored to 4.125 with Lunati 4.0 crank: $600 + $2100 + $2095 = $4795
Both are 427 CID motors.
New LQ4 block overbored to 4.060 with Lunati 4.125 crank: $600 + $350 + $2175 = $3125
New LQ4 block resleeved and overbored to 4.125 with Lunati 4.0 crank: $600 + $2100 + $2095 = $4795
Both are 427 CID motors.
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TECH Senior Member
Joined: Nov 2001
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Re: 4.25 stroke too much? please help :) How much clearancing of the block is required with the 4.25 stroke iron block motor? What rod needs to be used?
I am not against longer stroke motors at all. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
At our typical rpm limits (under 7000rpm with a 6500-6600rpm shift point) it isnt really an issue <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
4.030 and 4.25 stroke would be almost 434ci and would handle massive juice hehehe <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
4.060 x 4.25: 440ci <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
The 4.030 bore is the best for big nitrous shots however.
Cheers,
Chris
<small>[ September 27, 2002, 06:52 PM: Message edited by: Chris ARE 360 ]</small>
I am not against longer stroke motors at all. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
At our typical rpm limits (under 7000rpm with a 6500-6600rpm shift point) it isnt really an issue <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
4.030 and 4.25 stroke would be almost 434ci and would handle massive juice hehehe <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
4.060 x 4.25: 440ci <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
The 4.030 bore is the best for big nitrous shots however.
Cheers,
Chris
<small>[ September 27, 2002, 06:52 PM: Message edited by: Chris ARE 360 ]</small>
