408 vs. 421 Iron Stroker
408 vs. 421 Iron Stroker I know a lot of people don't like the 4.125 stroke on these engines, however, I can't help but think they are perfectly fine and reliable in the correct situation if TSP is building and selling the short blocks.
First off, this engine will go in a manual driver. This won't be a nitrous or forced induction engine, or a max HP engine.
SO, 2 questions....
#1 - What is your alls take on the 408 vs. 421 overall?
#2 - What increase in HP should i see with the 421 with a similar cam and the same LS3 top end I will be using?
First off, this engine will go in a manual driver. This won't be a nitrous or forced induction engine, or a max HP engine.
SO, 2 questions....
#1 - What is your alls take on the 408 vs. 421 overall?
#2 - What increase in HP should i see with the 421 with a similar cam and the same LS3 top end I will be using?
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I personally would not go above a 4" stroke as the rod angles are severe at 4" and the amount the bottom of the piston hangs out the bottom of the cylinder is a bit scarey. 408 is also 4.030" bore. Why not stick to 4.005" for strength and being able to rebore later with ease.
This will be a street only motor built to drive as many miles as I want. My goal is to have 500 RWHP minimum through a 6 speed and be very streetable in stop and go traffic if needed. I know this CAN be done with a 408 but I also figured the more cubic inches the more mild the overall build could be to reach my goals, assuming the larger cubic inches is reliable.
Anybody from TSP want to chime in?
Anybody from TSP want to chime in?
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Im going with the same route in my 98Z28 M6...Im thinking about going with the 6.0L Iron block with the 408 Rotating Assy. myself but thats just my choice. I do know that TSP has the Iron 408 LongBlock package where you can pick and choose how you want it build. The 408 Stroker with PRC 235cc heads and the Texas Giant cam is gonna be an easy route to your 500 RWHP mark. Of course you will need a good intake setup and larger headers. Preferably 1 7/8 to get the best gains IMO. Give em a call if you want more info... They can itemize you a build and work with you every step of the way.
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I'm also wondering about the reliability and streetability of the 421 from tsp to put into my Nissan 350z.
I spoke with Jake from tsp for about 30 min yesterday telling him what I'm looking for in my car when its all said and done-told him that I wanted a very streetable and almost bullet proof reliable 500+rwhp for daily driving, that has great traffic manners, that I could eventually put about 10psi boost to down the road. He said he'd put an itemized quote together for me. When I'm looking at it, he said that he and his tech both agreed that a 408 is the way to go for what I'm looking for-after reading all the posts about the 4.125 stroke I see why...
I spoke with Jake from tsp for about 30 min yesterday telling him what I'm looking for in my car when its all said and done-told him that I wanted a very streetable and almost bullet proof reliable 500+rwhp for daily driving, that has great traffic manners, that I could eventually put about 10psi boost to down the road. He said he'd put an itemized quote together for me. When I'm looking at it, he said that he and his tech both agreed that a 408 is the way to go for what I'm looking for-after reading all the posts about the 4.125 stroke I see why...
With the right cam spec I don't think drivability between the two would come into question. I would more worry about longevity. I would not do a 4.125" stroke motor if you are trying to put a ton of miles on it. The rod angle just does not promote that. I am personally a big fan of the 408 because of its potential. I know people say they aren't going to spray, but more often then not people get bored. I personally would hate to limit my hp potential in the future by going with a longer stroke setup. While they do make more low end power and torque, its not a big enough difference for me to give up the ability to hit the motor with a 200 shot. Just my .02 cents.
I think a lot of people would do that, but to properly build a 427 you need 12k which is not in everyone's budget. To take true advantage of the 427 c.i., or to be more specific, the extra bore size you would have to go with LS7 heads which are a pretty penny.
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Yea, that's pretty much what Jake told me, and what a lot of others have said in various threads I've read about the 408 vs 421...and, ya, I do plan on spraying after about a year or two, so the 408 is the way I'm going...really just for the longevity that he talked about earlier.
-so, I'm happy to say I pulled the trigger on it today, and got the prc ls3. 260cc heads
-accts should get the transfer tomorrow around lunch your time.
I can't wait to put that monster in my Z!
Thanks for all the info, and help TSP!!
-so, I'm happy to say I pulled the trigger on it today, and got the prc ls3. 260cc heads
-accts should get the transfer tomorrow around lunch your time.
I can't wait to put that monster in my Z!
Thanks for all the info, and help TSP!!
Last edited by ChrisMa; Oct 25, 2012 at 11:20 PM.
I know a lot of people don't like the 4.125 stroke on these engines, however, I can't help but think they are perfectly fine and reliable in the correct situation if TSP is building and selling the short blocks.
First off, this engine will go in a manual driver. This won't be a nitrous or forced induction engine, or a max HP engine.
SO, 2 questions....
#1 - What is your alls take on the 408 vs. 421 overall?
#2 - What increase in HP should i see with the 421 with a similar cam and the same LS3 top end I will be using?
First off, this engine will go in a manual driver. This won't be a nitrous or forced induction engine, or a max HP engine.
SO, 2 questions....
#1 - What is your alls take on the 408 vs. 421 overall?
#2 - What increase in HP should i see with the 421 with a similar cam and the same LS3 top end I will be using?
It had a Cola 4.125" crank in it and thats with the old 2002 SHORT sleeves. People have no idea what they're talking about saying its not good and won't work. BUT.....you might have excess oil burning.....maybe not. Brian Nutter at Wiseco has designed a piston that fights oil burning in a 4.125" stroke short sleeve/cylinder length.
After maybe 4 years into owning my 427ci it started burning oil.....I probably put 1qrt in every 2 weeks....but this was my only car, I drove the **** out of it daily.
My friend has an iron 422ci with a 4.125" stroke....he's been spraying a 300 shot for 8 years and the engine is still fine.
Do it....strokers are nice.
I'm having my Cola 4.125" crank cleaned up and resurfaced......gonna sell it for about $800.00. Perhaps the best crankshaft ever made for small block Chevy engines.....
Put that in an iron LQ9 408ci. and it could make 500 RWHP depending on top end. If thats not enough, it'll easily handle a 250 shot all day long.
.
Staging Lane
Joined: Jun 2012
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it comes down to who builds it...
If you want to do super stroke then I would have someone with more experience build it for you. 4" is stroking it to begin with and is the desired stroke if you are going with a power adder but lots of shops out there run bigger strokes to over 100,000 miles without issue. It comes down to who is specing and building the engine. Not trying to dis TSP here but they dont have the experience with more challenging builds that some other shops do.
If you want to do super stroke then I would have someone with more experience build it for you. 4" is stroking it to begin with and is the desired stroke if you are going with a power adder but lots of shops out there run bigger strokes to over 100,000 miles without issue. It comes down to who is specing and building the engine. Not trying to dis TSP here but they dont have the experience with more challenging builds that some other shops do.
have to take my hat off to you LS6427 
you have a 427ci with ls1 heads/TB, ls6 intake, baby cam and and a auto with a 12bolt and still made just about 500rwhp and more rwtq then alot of the higher end (streetable) 408s do lol
like is said, if i ever do it again i wont even think twice about it
you have a 427ci with ls1 heads/TB, ls6 intake, baby cam and and a auto with a 12bolt and still made just about 500rwhp and more rwtq then alot of the higher end (streetable) 408s do lol
like is said, if i ever do it again i wont even think twice about it
Teching In
Joined: Oct 2016
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My fully built and forged 427ci LS6 resleeved block just failed after 173,000 miles and 10+ years of beating the **** out of it. Rod finally broke doing 160mph....
It had a Cola 4.125" crank in it and thats with the old 2002 SHORT sleeves. People have no idea what they're talking about saying its not good and won't work. BUT.....you might have excess oil burning.....maybe not. Brian Nutter at Wiseco has designed a piston that fights oil burning in a 4.125" stroke short sleeve/cylinder length.
After maybe 4 years into owning my 427ci it started burning oil.....I probably put 1qrt in every 2 weeks....but this was my only car, I drove the **** out of it daily.
My friend has an iron 422ci with a 4.125" stroke....he's been spraying a 300 shot for 8 years and the engine is still fine.
Do it....strokers are nice.
I'm having my Cola 4.125" crank cleaned up and resurfaced......gonna sell it for about $800.00. Perhaps the best crankshaft ever made for small block Chevy engines.....
Put that in an iron LQ9 408ci. and it could make 500 RWHP depending on top end. If thats not enough, it'll easily handle a 250 shot all day long.
.
It had a Cola 4.125" crank in it and thats with the old 2002 SHORT sleeves. People have no idea what they're talking about saying its not good and won't work. BUT.....you might have excess oil burning.....maybe not. Brian Nutter at Wiseco has designed a piston that fights oil burning in a 4.125" stroke short sleeve/cylinder length.
After maybe 4 years into owning my 427ci it started burning oil.....I probably put 1qrt in every 2 weeks....but this was my only car, I drove the **** out of it daily.
My friend has an iron 422ci with a 4.125" stroke....he's been spraying a 300 shot for 8 years and the engine is still fine.
Do it....strokers are nice.
I'm having my Cola 4.125" crank cleaned up and resurfaced......gonna sell it for about $800.00. Perhaps the best crankshaft ever made for small block Chevy engines.....
Put that in an iron LQ9 408ci. and it could make 500 RWHP depending on top end. If thats not enough, it'll easily handle a 250 shot all day long.
.