Spinning to 7k
Thread Starter
Melting Slicks
Joined: Jun 2013
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Spinning to 7k
Okay so I just want to find out a few things here. On an L98 bottom end, this does not include the TPI intake, is it possible to go to 7k RPMs safely with some modifications? What is needed? I have heard somethings about the rod bolts being the ones that go first, and the main cap bolts being the ones that cause the engine to shake itself apart. So I'm just wondering, how true is this? Because we all know you don't need forged internals and all that jazz to get to 7k, the ricers do it and some times can't even handle 300 hp, but they can get to 7k.
Would you need a better oil pump? Bigger oil pan?
Just for education here. Thanks!
Would you need a better oil pump? Bigger oil pan?
Just for education here. Thanks!
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Reliably no that stock L98 is going to pop period
Unfortunately theres nothing "performance" about the shortblocks sam ething they have in station wagons and trucks.
forged bottom end 4 bolt caps recommended. Those ricers have some stout blocks for their size and dont move around much. Better engineered too.
Every wannabe circle track guy is going to tell you they do 7k wtih stock stuff maybe better rod bolts those go too...and 2 bbl wonders only make about 350hp anyway.
Do it right the first time, spend the money once.
Unfortunately theres nothing "performance" about the shortblocks sam ething they have in station wagons and trucks.
forged bottom end 4 bolt caps recommended. Those ricers have some stout blocks for their size and dont move around much. Better engineered too.
Every wannabe circle track guy is going to tell you they do 7k wtih stock stuff maybe better rod bolts those go too...and 2 bbl wonders only make about 350hp anyway.
Do it right the first time, spend the money once.
Thread Starter
Melting Slicks
Joined: Jun 2013
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Well I Have AFR 195 Heads, With their valve Train And Comp Cams Roller Rockers With Crane Cams Hardened Chromoly Push Rods And Melling flat Hydraulic Lifters. I Think My Top End would Be Sufficient Enough.
Melting Slicks
Joined: Nov 2010
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From: Michigan
I drag raced a stock bottom end 450hp 350 4 bolt for a few years, 6500 shifts with who knows how many miles before I rebuilt it(tad lighter than stock hypertech pistons). I paid for ARP rod bolts, but didn't get them and was too young n dumb too check for the correct bolts. If I knew it didn't have those arp rod bolts I'd of shifted at 6000 and I do with my C3 L48 and will with my C4 L98 total stock bottom ends.
Still your 85 has oem forged pistons(trw leftovers I read somewhere) and even an old heavier style(like yours and my example) trw domed 400 piston is lighter than a stock cast dish 350. Well I'd assume a 85 forged piston is lighter and maybe someone has a weight or can weigh one. Maybe the lighter pistons would give you a little more safe rpm, how much no clue.
Still your 85 has oem forged pistons(trw leftovers I read somewhere) and even an old heavier style(like yours and my example) trw domed 400 piston is lighter than a stock cast dish 350. Well I'd assume a 85 forged piston is lighter and maybe someone has a weight or can weigh one. Maybe the lighter pistons would give you a little more safe rpm, how much no clue.
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From: Database Error Indiana
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Team Owner
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From: Park City Utah
Tell us this: How can AFR supply a spring and make an RPM claim when they don't know cam you will be using??
Thread Starter
Melting Slicks
Joined: Jun 2013
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Because the question was at what point will the components become unsafe to use at that RPM, not if they can get there. And I'm sure my cam could get to 6800 RPMs.
Team Owner
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Why not take your engine to a race engine builder and have him set you up?
Like this: "Keith (Black), I wanna a screamer that spins to 7200 RPM.
Like this: "Keith (Black), I wanna a screamer that spins to 7200 RPM.
Team Owner
Joined: Aug 2004
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From: Park City Utah
Thread Starter
Melting Slicks
Joined: Jun 2013
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Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
You give me the "crazy" sign when you are that one who has no clue.
How can AFR make a specific RPM claim for springs, when they don't know what cam you are using. The fact that THAT question doesn't make you "wake up", shows how clueless you really are.
Ya claim "Ricers can do it!" which is so misguided it's unbelievable. "Ricers", have shorter stroke. Smaller pistons (lighter). Stiffer, stronger blocks that support the cranks better. There is NO comparison at all. My RC airplane motor spins 17k...so my Small Block Chevy should be able to also. See? No comparison.
Since you don't "get it"...I'll suggest what others have; go out and rip 'er to 7k and let us know how it works out for you.
How can AFR make a specific RPM claim for springs, when they don't know what cam you are using. The fact that THAT question doesn't make you "wake up", shows how clueless you really are.
Ya claim "Ricers can do it!" which is so misguided it's unbelievable. "Ricers", have shorter stroke. Smaller pistons (lighter). Stiffer, stronger blocks that support the cranks better. There is NO comparison at all. My RC airplane motor spins 17k...so my Small Block Chevy should be able to also. See? No comparison.
Since you don't "get it"...I'll suggest what others have; go out and rip 'er to 7k and let us know how it works out for you.
Thread Starter
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
You give me the "crazy" sign when you are that one who has no clue.
How can AFR make a specific RPM claim for springs, when they don't know what cam you are using. The fact that THAT question doesn't make you "wake up", shows how clueless you really are.
Ya claim "Ricers can do it!" which is so misguided it's unbelievable. "Ricers", have shorter stroke. Smaller pistons (lighter). Stiffer, stronger blocks that support the cranks better. There is NO comparison at all. My RC airplane motor spins 17k...so my Small Block Chevy should be able to also. See? No comparison.
Since you don't "get it"...I'll suggest what others have; go out and rip 'er to 7k and let us know how it works out for you.
How can AFR make a specific RPM claim for springs, when they don't know what cam you are using. The fact that THAT question doesn't make you "wake up", shows how clueless you really are.
Ya claim "Ricers can do it!" which is so misguided it's unbelievable. "Ricers", have shorter stroke. Smaller pistons (lighter). Stiffer, stronger blocks that support the cranks better. There is NO comparison at all. My RC airplane motor spins 17k...so my Small Block Chevy should be able to also. See? No comparison.
Since you don't "get it"...I'll suggest what others have; go out and rip 'er to 7k and let us know how it works out for you.
Team Owner
Joined: Aug 2004
Posts: 21,543
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From: Park City Utah
You THINK that I make no sense at all, b/c you don't know WTF you're talking about here. The title of your thread makes that abundantly clear right off the bat...then everything you say going forward backs it up.
Do you think that a mild cam creates as much valve velocity and force as a radical/aggressive cam? No. An aggressive cam opens a valve faster, further, and closes faster than a mild cam. SO...how can AFR (or anyone) make a universal claim about an RPM when they don't know your cam, lifters, pushrods, rockers....How can that be? They can't. All they can do is give a general estimation based on common combos. The cam grinder would know far more about the right valve spring, then the head manufacturer would.
Which is why it's laughable when you say; "AFR's website says that the springs that came with my heads can go to 6800, which is pretty close"
Do you think that a mild cam creates as much valve velocity and force as a radical/aggressive cam? No. An aggressive cam opens a valve faster, further, and closes faster than a mild cam. SO...how can AFR (or anyone) make a universal claim about an RPM when they don't know your cam, lifters, pushrods, rockers....How can that be? They can't. All they can do is give a general estimation based on common combos. The cam grinder would know far more about the right valve spring, then the head manufacturer would.
Which is why it's laughable when you say; "AFR's website says that the springs that came with my heads can go to 6800, which is pretty close"
Last edited by Tom400CFI; Feb 12, 2014 at 01:18 AM.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
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From: Michigan
RPM rating of a spring by afr is a best guess. The spring does more than close the valve, it keeps the lifter on the cam lobe and an aggressive cam will need more spring at higher rpm. But if your other parts can't handle the heavier pressure you can still have trouble.
Melting Slicks
Joined: Feb 2014
Posts: 2,409
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From: NC
Can I ask..why are you wanting to spin to 7k?
Better solution... buy an LT5. It'd save you a boat load of money than building a normal SBC that can handle 7k.
Unless you're beating the utter snot out of the car on a circle track that 7k mark isn't something you're going to be kissing often. Even in racing, unless you're running some pretty steep rear gears.
You'd have to reinforce the block (That stock 2 bolt main isn't going to cut it), get a better crank, pistons, rods, studs and bolts all the way around, a high rpm camshaft, pushrods, (maybe Titanium) lighter valves would be a good start too.
I'm assuming you don't have the LTR intake setup anymore either. Because if you do, you need to change that as well, because the LTR won't breathe at that RPM at all. Even with large aftermarket runners, a ported plenum, and a Ported Aftermarket Lower Intake.
I'd go More Displacement loong before I'd be shooting for 7k rpm.
Better solution... buy an LT5. It'd save you a boat load of money than building a normal SBC that can handle 7k.
Unless you're beating the utter snot out of the car on a circle track that 7k mark isn't something you're going to be kissing often. Even in racing, unless you're running some pretty steep rear gears.
You'd have to reinforce the block (That stock 2 bolt main isn't going to cut it), get a better crank, pistons, rods, studs and bolts all the way around, a high rpm camshaft, pushrods, (maybe Titanium) lighter valves would be a good start too.
I'm assuming you don't have the LTR intake setup anymore either. Because if you do, you need to change that as well, because the LTR won't breathe at that RPM at all. Even with large aftermarket runners, a ported plenum, and a Ported Aftermarket Lower Intake.
I'd go More Displacement loong before I'd be shooting for 7k rpm.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
its all a learning process this engine stuff
7k can be fun but its hard on parts only real purpose is because the combo has to run up there and most street engines are done well before then
Mines set up to run that high and a valve lash check 2x a yr, checking springs 1x a yr or so is just part of it.
Even then something can let go wiht the best of parts
Gen1 SBC is still a cheap way to great horsepower iwth the parts we have today. Sure an LT5 can spin that high but it isnt making any power up there just heat and neat sounds btdt.
You got a nice set of heads Dan if you run a bone stock L98 to 7k you could risk popping that bottom end and damaging them.(say if a piece of piston skirt lets go and takes a walk through the combustion chamber lol)
You can do up a shorblock that will handle it for not too much no exotic stuff needed.
I run mine up to 7k once in awhile not often. Most the time honestly 6500 is plenty on the street. Many wouldnt consider it a street car with the manners it has below 3k.
There are days when I too think "shoulda gone much larger" and shot for a max of 62-6300 or so it will be funner and live much longer. One day
7k can be fun but its hard on parts only real purpose is because the combo has to run up there and most street engines are done well before then
Mines set up to run that high and a valve lash check 2x a yr, checking springs 1x a yr or so is just part of it.
Even then something can let go wiht the best of parts
Gen1 SBC is still a cheap way to great horsepower iwth the parts we have today. Sure an LT5 can spin that high but it isnt making any power up there just heat and neat sounds btdt.
You got a nice set of heads Dan if you run a bone stock L98 to 7k you could risk popping that bottom end and damaging them.(say if a piece of piston skirt lets go and takes a walk through the combustion chamber lol)
You can do up a shorblock that will handle it for not too much no exotic stuff needed.
I run mine up to 7k once in awhile not often. Most the time honestly 6500 is plenty on the street. Many wouldnt consider it a street car with the manners it has below 3k.
There are days when I too think "shoulda gone much larger" and shot for a max of 62-6300 or so it will be funner and live much longer. One day
Last edited by cv67; Feb 12, 2014 at 06:27 AM.