Cost to rev higher

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PackardV8
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Re: Cost to rev higher

Post by PackardV8 »

Bigchief632 wrote: Mon Nov 28, 2022 2:08 pm
PackardV8 wrote: Mon Nov 28, 2022 1:51 pm When customers ask about building for higher RPM, I tell them, "Revs are the most expensive horsepower to build and to maintain. Displacement horsepower is cheap to build and cheap to maintain. Unless building to a displacement-limited class, go bigger and turn it slower."
I prefer building a bigger displacement AND turning it more rpm. They make A LOT more power that way.
The other old speed shop quote:
"Speed costs money. How fast can you afford to go?"
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Re: Cost to rev higher

Post by mt-engines »

Bigchief632 wrote: Mon Nov 28, 2022 2:08 pm
PackardV8 wrote: Mon Nov 28, 2022 1:51 pm When customers ask about building for higher RPM, I tell them, "Revs are the most expensive horsepower to build and to maintain. Displacement horsepower is cheap to build and cheap to maintain. Unless building to a displacement-limited class, go bigger and turn it slower."
I prefer building a bigger displacement AND turning it more rpm. They make A LOT more power that way.
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Re: Cost to rev higher

Post by mt-engines »

PackardV8 wrote: Mon Nov 28, 2022 2:21 pm
Bigchief632 wrote: Mon Nov 28, 2022 2:08 pm
PackardV8 wrote: Mon Nov 28, 2022 1:51 pm When customers ask about building for higher RPM, I tell them, "Revs are the most expensive horsepower to build and to maintain. Displacement horsepower is cheap to build and cheap to maintain. Unless building to a displacement-limited class, go bigger and turn it slower."
I prefer building a bigger displacement AND turning it more rpm. They make A LOT more power that way.
The other old speed shop quote:
"Speed costs money. How fast can you afford to go?"
Well to be honest a 230@.050 cam costs the same as a 270@.050 cam.. and the springs could be within 100 bucks of another.. so..
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Re: Cost to rev higher

Post by PackardV8 »

mt-engines wrote: Mon Nov 28, 2022 3:39 pm
PackardV8 wrote: Mon Nov 28, 2022 2:21 pm
Bigchief632 wrote: Mon Nov 28, 2022 2:08 pm

I prefer building a bigger displacement AND turning it more rpm. They make A LOT more power that way.
The other old speed shop quote:
"Speed costs money. How fast can you afford to go?"
Well to be honest a 230@.050 cam costs the same as a 270@.050 cam.. and the springs could be within 100 bucks of another.. so..
That slope is way steeper and much more slippery. There are the more expensive valves, tool steel retainers, stiffer pushrods, better quality rocker arms with a girdle, better ignition, better lifters,et al.
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Re: Cost to rev higher

Post by n2omike »

My recent 363 SBF spins to 8k rpm. Peaked at 7300 and only lost 5hp out to 8k.

Big carb, big intake, big heads, good rotating assembly... and most of all, a good valvetrain.
Small blocks have smaller valves and can get by without going to Titanium more easily than big blocks.
My heads are Trick Flow High Ports. The intake valves were enlarged to 2.125" but a 5/16" stem was used to save weight.
Solid roller 258/264 @ 0.050" on a 108. 0.740" net intake lift. 3/8" thick wall pushrods, Tool Steel retainers, Crower Stainless shaft rockers. 245/600 lb Isky Tool Room (PSI) springs. Stuck with 1-3/4" headers for now.

Has around 120 dyno runs/dragstrip passes and a few hundred street miles. Zero issues.

I went with stainless valves for longer service life and better endurance. If you go with Titanium, be sure to get ones that are coated with Chromium Nitride. (CRN). Lots of cheap NASCAR surplus stuff out there from the 2000-2004 era, but it's not CRN. New CRN stuff isn't cheap. lol

Cheap/Fast/Reliable... CHOOSE TWO. lol
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Re: Cost to rev higher

Post by jeff swisher »

Almost All stock parts from a 1969 300 HP 350 Not bored Crank not turned.
Pistons were upgraded to Cast 345NP and rings E251K cylinder walls were left with the 100,000 mile golden glaze polish.
New Bearings.
Stock bolts rods not resized Not balanced but new standard bore pistons are 30 grams lighter than factory ones.

1969 #186 heads milled and ported and stock valves used that were in the heads New valve job.
Z28 springs Old 270H 224 @ .050 .470" lift 110 LSA cam Iron Q jet intake Ported Ported exhaust manifolds. Q jet 750.

Keeping it way inexpensive here see.
Stock rocker studs and stock rockers and pushrods. Ground down stock retainers. New keepers though :)

Sweet spot on the shift was 6900 RPM it would pull to 7400.
Later stuck in a Herbert Solid flat tappet 235-245@ .050 .500" lift 108 LSA Headers and Tunnel-ram intake.
7600 rpm and it seen it daily and I pulled the cam and lifters after 75,000 miles and gave it to a buddy.

He ran it 2 years in his dirt car.

I still have that engine today but with Ported 601 heads and a 268H cam.
It has seen many 7600 rpm shifts and 2 8000 rpm peg the tach missed shifts by friends.

Every thing is square and round where it should be and the old school cams I run are very rev happy.

I run Beehive PAC springs today as I have had some of the newer "Z" springs break.
I DO NOT like a spring with damper anymore.

That same 1969 engine has been in 4 vehicles and I ran the highway at 6500 RPM for 15 miles.
It does not take much money to have a 7500 RPM reliable engine.

This 1969 350 has over 400,000 hard miles on it and still perfect bore and no crank wear.
Keep good oil and filters in them.
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Re: Cost to rev higher

Post by David Redszus »

BobbyB wrote: Thu Nov 24, 2022 7:02 pm Street/Strip SBC or SBF safely revs to 6000 rpm
How much more money and how much shorter life to build to:
Safely rev to 6500 rpm?
Safely rev to 7000 rpm?
Safely rev to 7500 rpm?
Safely rev to 8000 rpm?
What is the bore, stroke and rod length of current engine?
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Re: Cost to rev higher

Post by thecarfarmer »

PackardV8 wrote: Mon Nov 28, 2022 8:38 pm
mt-engines wrote: Mon Nov 28, 2022 3:39 pm
PackardV8 wrote: Mon Nov 28, 2022 2:21 pm The other old speed shop quote:
"Speed costs money. How fast can you afford to go?"
Well to be honest a 230@.050 cam costs the same as a 270@.050 cam.. and the springs could be within 100 bucks of another.. so..
That slope is way steeper and much more slippery. There are the more expensive valves, tool steel retainers, stiffer pushrods, better quality rocker arms with a girdle, better ignition, better lifters,et al.
The old "bottom of the page cam is no more than the top of the page cam" dilemma...

... followed by the "if I'm going to step up to this, then if better upgrade that" loop...

...enough iterations, and the grocery getter has just become a comp eliminator car
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Re: Cost to rev higher

Post by BobbyB »

David Redszus wrote: Tue Nov 29, 2022 8:00 pm
BobbyB wrote: Thu Nov 24, 2022 7:02 pm Street/Strip SBC or SBF safely revs to 6000 rpm
How much more money and how much shorter life to build to:
Safely rev to 6500 rpm?
Safely rev to 7000 rpm?
Safely rev to 7500 rpm?
Safely rev to 8000 rpm?
What is the bore, stroke and rod length of current engine?
4.030”
3.400”
5.400”
347 ford with factory 1974 block
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Re: Cost to rev higher

Post by David Redszus »

B --4.030
S --3.4
R --5.4
SCR -10.0-1
DCR - 7.93-1
BMEP - 10.32
Torque - 345

RP.M.....MSp m/s..Load lb..Power hp
6000......17.27....2745.....395
7000......20.15....3736.....461
8000......23.06....4880.....526
8600......24.76....5639.....565

I would redline this engine at 8600rpm, providing the valve train can
withstand valve float. The piston loading becomes fairly high as well.
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Re: Cost to rev higher

Post by Alaskaracer »

Bigchief632 wrote: Mon Nov 28, 2022 2:08 pm I prefer building a bigger displacement AND turning it more rpm. They make A LOT more power that way.
Yep, I agree. Cubes AND rpm......the direction I've gone and it's been a good move......
Mark Goulette
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Speed kills but it's better than going slow!
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Re: Cost to rev higher

Post by Lloyd klem »

This is late 2022.8000 rpm is not a large perimeter to meet at all.Most things I get to work with launch from that rpm or start the Dyno pull there.Guys were running 8000 rpm with garbage 30 yrs ago.Some ran pretty good,some ran quite awhile.Some came apart hugely.Today the parts that are available 8000 rpm has pretty good longevity and have been well established in several forms of racing.
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Re: Cost to rev higher

Post by jsgarage »

Question: Street/Strip SBC or SBF safely revs to 6000 rpm.
How much more money and how much shorter life to build to:
Safely rev to 6500 rpm?
Safely rev to 7000 rpm?
Safely rev to 7500 rpm?
Safely rev to 8000 rpm?

One of our go-faster members set out to answer this age-old question in his '66 autocross Mustang. Started with a Mexican block, good aftermarket balance job, upgraded rods, forged pistons. Then cam after cam, magic valve springs, head work etc. Ran fine at 6000 and with autocross you're only looking at maybe 90-100 seconds for full-bore runs. Next chip in the rev limiter was 6250; still fine and a little faster. He started winning his class. Same with 6500- really sounded nice. Next week at 6850, the crank broke at #4 main, splitting the block vertically separating the last 2 cylinders from the rest of the block. Game over for everything below the cylinder heads including bent clutch & flywheel. The frame is easily fixable.

An often overlooked problem with hi-rpm failures is, the inertia of all those parts flying around becomes great enough that its more difficult to do post-mortems as the remains become smaller. Smokey Yunick called this "weak-link engineering": you quit when the goal is met or you run out of money. He's not sure at this point whether he continues to explore rpms on track or stays married. Wife is a really good cook......
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Re: Cost to rev higher

Post by Alaskaracer »

ANY engine will rev as high as you want it to....How well it stays together and lasts will depend on how much you spend....quality parts aren't cheap...and cheap parts aren't always quality.....
Mark Goulette
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Speed kills but it's better than going slow!
http://www.livinthedreamracing.com
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Re: Cost to rev higher

Post by 289nate »

Piston speed and pushrod length should be part of the discussion.
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