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Old 11-16-2012, 01:10 PM   #1
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402 stroker or ls7

Been building a new 402 stroker but now am considering maybe going with a ls7. What are the pro's and con's
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Old 11-16-2012, 01:17 PM   #2
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My amateur 2 cents:

Pros:

higher revving with an over-square piston dimension
7K rpm 427cid

Cons:

figuring out how to transfer the dry sump system (If I were doing it)

That's what I'd have trouble figuring out anyways
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Old 11-16-2012, 01:46 PM   #3
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402 Stroker...LS7's make great power but in car as heavy as the GTO id go 402 stroker with production or aftermarket cathedral port heads...may not make as much peak HP as LS3/LS7 headed cars but torque will be much better In my opinion
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Old 11-16-2012, 08:19 PM   #4
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well it looks like the ls7 deal isnt going to happen so on to finishing the 402 short block i have.
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Old 11-16-2012, 08:26 PM   #5
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Quote:
Originally Posted by mike27408...View Post
402 Stroker...LS7's make great power but in car as heavy as the GTO id go 402 stroker with production or aftermarket cathedral port heads...may not make as much peak HP as LS3/LS7 headed cars but torque will be much better In my opinion

You don't really believe a N/A 402 is going to come close to an LS7 do you?
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Old 11-16-2012, 08:27 PM   #6
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Quote:
Originally Posted by sakeunited...View Post
My amateur 2 cents:

Pros:

higher revving with an over-square piston dimension
7K rpm 427cid

Cons:

figuring out how to transfer the dry sump system (If I were doing it)

That's what I'd have trouble figuring out anyways

Everything else being equal ( balance, coatings, etc) you should be able to rev the 402 as high/higher than the 427. 402 would have a smaller circumference, so less surface area friction, and less piston mass on the same rod and stroke. Can a more experienced member please veify/discredit my modest understanding please?
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Old 11-16-2012, 08:28 PM   #7
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Quote:
Originally Posted by sakeunited...View Post
My amateur 2 cents:

Pros:

higher revving with an over-square piston dimension
7K rpm 427cid

Cons:

figuring out how to transfer the dry sump system (If I were doing it)

That's what I'd have trouble figuring out anyways

You do not need to run a dry sump system with an LS7 in a gto.
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Old 11-16-2012, 08:32 PM   #8
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Quote:
Originally Posted by GTO_gotta_go...View Post
You don't really believe a N/A 402 is going to come close to an LS7 do you?

If done correctly an na 402 is pretty stout. If both optimized I don't see why they wouldn't be pretty close. It's only 25ci.
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Old 11-17-2012, 05:31 AM   #9
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Quote:
Originally Posted by eaglegoat...View Post
Everything else being equal ( balance, coatings, etc) you should be able to rev the 402 as high/higher than the 427. 402 would have a smaller circumference, so less surface area friction, and less piston mass on the same rod and stroke. Can a more experienced member please verify/discredit my modest understanding please?

MY thought is that it would be harder to rev that high because of the increased piston speed of the longer than stock LS2 stroke? but then again the forged assembles are stronger than OEM

Quote:
Originally Posted by GTO_gotta_go...View Post
You do not need to run a dry sump system with an LS7 in a gto.

didn't know that, thank you
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Old 11-17-2012, 05:54 AM   #10
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Mod for mod a 427 will always have more power and torque than a 402.
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Old 11-17-2012, 06:05 AM   #11
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when it comes down to it 25 ci is the difference. now i just have to figure out what head and cam i want on the 402 planning on staying with a ls2 style head.
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Old 11-17-2012, 08:35 AM   #12
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Quote:
Originally Posted by GTO_gotta_go...View Post
You do not need to run a dry sump system with an LS7 in a gto.

This is correct, although you'll need a short snout crank for wet oiling instead of the long snout dry sump oiling crank. Also, the LS7 block does not come pre-drilled for an oil dipstick since it was designed for dry sump oiling. For wet sump oiling, you will need to drill the dipstick hole. To be honest, the LS7 block is not that strong. A sleeved LS2 block is probably the better route to go if you want a 427.
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Old 11-17-2012, 09:09 AM   #13
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Quote:
Originally Posted by batboy...View Post
This is correct, although you'll need a short snout crank for wet oiling instead of the long snout dry sump oiling crank. Also, the LS7 block does not come pre-drilled for an oil dipstick since it was designed for dry sump oiling. For wet sump oiling, you will need to drill the dipstick hole. To be honest, the LS7 block is not that strong. A sleeved LS2 block is probably the better route to go if you want a 427.

true
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Old 11-17-2012, 09:22 AM   #14
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Quote:
Originally Posted by mike27408...View Post
402 Stroker...LS7's make great power but in car as heavy as the GTO id go 402 stroker with production or aftermarket cathedral port heads...may not make as much peak HP as LS3/LS7 headed cars but torque will be much better In my opinion

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Old 11-17-2012, 09:50 AM   #15
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Quote:
Originally Posted by GTO_gotta_go...View Post
You don't really believe a N/A 402 is going to come close to an LS7 do you?

Not in peak hp...but all around power and torque in a 4000 lb car and on a budget id go 402 all day long...
I dont care what kind of food fight it starts LS7's are over rated...Ive seen 2 N/A 402's make 570RWHP/510RWTQ with out having to turn 7K rpm(one with trick flows one with AFR's) running in the mid-hi 10's on motor
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Old 11-17-2012, 09:52 AM   #16
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dollar for dollar 402 is a better bang for the buck

Last edited by mike27408; 11-17-2012 at 09:55 AM.
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Old 11-17-2012, 10:23 AM   #17
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resleeving an LS2 block $2000.00 in machine work alone , LS7 heads minimum of $2500.00 for stock take off heads from ebay not taking into account most people try to keep the Ti valves, offset rockers , LS7 intake , wet sumps vs. dry sump
F all that BS
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Old 11-17-2012, 10:27 AM   #18
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Quote:
Originally Posted by mike27408...View Post
resleeving an LS2 block $2000.00 in machine work alone , LS7 heads minimum of $2500.00 for stock take off heads from ebay not taking into account most people try to keep the Ti valves, offset rockers , LS7 intake , wet sumps vs. dry sump
F all that BS

Let me guess... you have a 402 stroker...

And certainly whatever you have must be the best...

Hopefully, Chevrolet sees your posts and starts putting 402's in their Z06's.
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Old 11-17-2012, 11:13 AM   #19
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Quote:
Originally Posted by sakeunited...View Post
MY thought is that it would be harder to rev that high because of the increased piston speed of the longer than stock LS2 stroke? but then again the forged assembles are stronger than OEM

We are comparing 402 ls2 and 427 ls7. Both have a 4". Stroke. Stock ls2 stroke is 3.622.
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Old 11-17-2012, 11:22 AM   #20
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Quote:
Originally Posted by GTO_gotta_go...View Post
You don't really believe a N/A 402 is going to come close to an LS7 do you?

The power comes from the heads
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Old 11-17-2012, 02:17 PM   #21
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Quote:
Originally Posted by GTO_gotta_go...View Post
You do not need to run a dry sump system with an LS7 in a gto.

If you mean both modded not nearly but I wouldn't mind a 505 crank hp 402


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Old 11-17-2012, 02:46 PM   #22
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Quote:
Originally Posted by sakeunited...View Post
If you mean both modded not nearly but I wouldn't mind a 505 crank hp 402.

http://www.ls1gto.com/forums/showthread.php?t=443912
I know its more power than you asked for but you can make him an offer.

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Old 11-17-2012, 03:30 PM   #23
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No wrong answer. Dollar wise the 402 is a better deal. If money was no object I'd drop in a 427 in a hot minute.
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Old 11-17-2012, 03:40 PM   #24
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Quote:
Originally Posted by eaglegoat...View Post
Everything else being equal ( balance, coatings, etc) you should be able to rev the 402 as high/higher than the 427. 402 would have a smaller circumference, so less surface area friction, and less piston mass on the same rod and stroke. Can a more experienced member please veify/discredit my modest understanding please?

the piston's larger diameter stabilizes it more in the cyl bore than the 402 piston. More stable = less side loading = less friction. Over-square vs square. You're right about piston mass though, so if the rod bolts are the limiting factor, then you could be right, but then the solution is a cheap set of rod bolts

Quote:
Originally Posted by mike27408...View Post
Not in peak hp...but all around power and torque in a 4000 lb car and on a budget id go 402 all day long...
I dont care what kind of food fight it starts LS7's are over rated...Ive seen 2 N/A 402's make 570RWHP/510RWTQ with out having to turn 7K rpm(one with trick flows one with AFR's) running in the mid-hi 10's on motor

but i've seen LS7's push 650whp cam only... soooh...

besides, if someone is making the argument of more area under the curve, but not necessarily more peak power, then displacement is the place to look.
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Old 11-17-2012, 03:41 PM   #25
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Originally Posted by SJFGTO...View Post
No wrong answer. Dollar wise the 402 is a better deal. If money was no object I'd drop in a 427 in a hot minute.

For the money I'd personally go for a 418 $200 more than a 402 from tsp.
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Old 11-17-2012, 04:21 PM   #26
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Don't forget I believe sensors have different connectors. So that would mean cutting and splicing I believe.

Also, my vote is for a 402. It's just easier in my mind. I would love a ls7 don't get me wrong lol.
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Old 11-17-2012, 05:09 PM   #27
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Originally Posted by GDL...View Post
Don't forget I believe sensors have different connectors. So that would mean cutting and splicing I believe.

Also, my vote is for a 402. It's just easier in my mind. I would love a ls7 don't get me wrong lol.

it means swapping his existing sensors over...?
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Old 11-17-2012, 05:45 PM   #28
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There's a bit of brain damage in here.
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Old 11-17-2012, 06:11 PM   #29
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ERL 404-416 $3650 +core
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Old 11-17-2012, 06:29 PM   #30
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Somebody call me?













ERL 404-416 $3650 +core
ERL 427-454 $5500 +core
SDPC 402 $4500 outright

no, no one asked what cam to use! lol

comparing prices of engines from different vendors is kind of apples to oranges. compare TSP's engines with their own, ERLs with their own, etc. to find price differences between the 402 and 418 options
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