Top speed of an SB stroker

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brewil

brewil

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Im curious what the top speed of a SB 408 might be, forged internals with H beams, Air Gap, Solid Flat tappet 246/252@50 with 600 lift, Dana 60 3.54 gears

just an average idea?
 
what size tires...diameter ?

what is the max rpm?
 
All you realy need to know is the RPM, tire hight, and gears.

Then use this to find out.

Tire hight divided buy two divided buy gears X RPM divided buy 168.


So lets say

26 divided by 2 divided by 3.23 X 6000RPM divided by 168=143.74
 
These speed charts are only theoretical speeds, they won't take into account wind, tire resistance, etc. which is usually what tops out a car. Cars usually run out of HP before they run out of RPM.

This is what is limiting the speed of my Crossfire to 154mph. It runs out of HP before the PRM hits redline.

Granted your 408 will have more HP than my Crossfire but you are trying to push a brick through the air while I am pushing a car with a lower drag coefficient.


Chuck
 
flat out on the highway? the 3.54 gear is gonna hold ya back depending how high ya want to rev that *****. i know my stock 360 with 2.94 gears will go 120 with ease.
 
I've seen 145 in my Dart for a short period. 408 stroker with an A518 OD tranny and 3.23 gears, 27" tall tires. Still had plenty to go but I was running out of empty interstate....
 
brewil said:
Im curious what the top speed of a SB 408 might be, forged internals with H beams, Air Gap, Solid Flat tappet 246/252@50 with 600 lift, Dana 60 3.54 gears

just an average idea?
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In a 30 plus year old A body, it will go fast enough to make you slow back down.
 
You mean to ask, "what is the max safe rpm" the motor can take. My guess, just a guess 7,500 maybe more but $$$, the block is the weakest area. With a $3,00 racing block 8,000 plus.

So lets say a super safe 7,000 rpm. With 3.55 gears and 27 inch tires, you be at around 150 mph. Fast enough to make the 11 o clock news, ha ha
 
We were at the track earlier this week with a '68 Valiant. It went about 145 mph on the back straight. Given more room it could go faster, maybe 155 or 160 max. With different gears it might go a bit faster but the aero isn't very good on those cars. Engine is a 427 with Edelbrock heads and a 650 carb.
 
I think of the times I went over a hundred in my Signet while just today I drove a few miles on I-5 in my 6 cylinder Mercedes coupe' at 130 just to clean it out. There's more to it then just an engine
 
In a 30 plus year old A body, it will go fast enough to make you slow back down.
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You can believe that chitttt, I have a 410 stroker in my 70 Dart with 4spd and 355 gears with a 26" tire on it. It is pretty scary on the pipe in 3rd gear, bang 4th and I don't trust it on the street at all, the front and rear starts to float and it forces me to get out of it at around 120-130 MPH! It gets there quickly too:-D
 
340mopar said:
Man, this is the quote that says it all. No truer words can be spoken.



Chuck
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IF, you have stock suspesion and alignment on it.

Tim Werner in his 68 Valiant just hit 150mph on the straight-a-way at PIR Raceway in Portland on Monday. He said it had a lot left. He has a 427 sb stroker with over 500 HP. He said the car will now run with C6 Z06's on the road course!. Before the new motor it could only run with C5 Z06's.

A C6 Z06 Corvette is a world class supercar.

The ARengineering's latest Baer conversion brakes worked great to haul the car down from 150mph for the next turn.

Tim's Valiant...

TimWerner68Valiant1.jpg
 
Awesome, just was curious. There's no way I will go much over the speed limit. I' going alterkation and street lynx and chassis stiffening under and in the engine bay. 0-60 will be under 6 secs? do you guys think?

thanks for all the replies
 
340mopar said:
These speed charts are only theoretical speeds, they won't take into account wind, tire resistance, etc. which is usually what tops out a car. Cars usually run out of HP before they run out of RPM.

This is what is limiting the speed of my Crossfire to 154mph. It runs out of HP before the PRM hits redline.

Granted your 408 will have more HP than my Crossfire but you are trying to push a brick through the air while I am pushing a car with a lower drag coefficient.


Chuck
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Gearing has a lot to do with it too. My Shelby Daytona would run faster (135ish) in 4th than it would in 5th (130ish).

FWIW, 130ish is the fastest I have pushed my 68 Barracuda with a 360. The front end starts to get light and the car is moving around in its lane. I would need to get the car closer to the ground and add some spoilers if I wanted to go faster and feel comfortable.
 
dgc333 said:
FWIW, 130ish is the fastest I have pushed my 68 Barracuda with a 360. The front end starts to get light and the car is moving around in its lane. I would need to get the car closer to the ground and add some spoilers if I wanted to go faster and feel comfortable.
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sounds familiar.he he

you end up changing lanes, like you meant to..

but really it just so you don't lose it and crash.lol

it's thrilling.
 
My old 62 Valiant, 225 & 4sp, 3.23 gears, would do 5,000rpm in 4th and that was 120mph. It wasn't all over the road either, very steady....helps when you spend a bit of coin on the suspension.
 
Yeah Im going RMS suspension. My Hemi 265 did about 120 with 2.72 gears and a 3 speed but I want that big V8 pooooowwwwwweeeeerrrrr
 
cjh said:
My old 62 Valiant, 225 & 4sp, 3.23 gears, would do 5,000rpm in 4th and that was 120mph. It wasn't all over the road either, very steady....helps when you spend a bit of coin on the suspension.
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yes the suspension / aligment is 'key'
But yeah and your car weighs 2700lbs +/- and probably does not have ss springs sitting a mile off the ground and raked...

my 71 dart with 225 would also do the same as yours and not be all over the road, but this like you are saying-120'ish

try 140'ish+ some time.
 
I recall the mid 70's 440 cop cars. Not like really quick but could do an honest 140 mph--and not with an electronic speedometer that keeps climbing even thou the car doesn't feel like its picking up speed!

I went for a ride in that 440 grand fury cop car. Pulled hard when the cop punched it in first gear and we had 7 people in the car. Cop was laughing how other cars might be quicker but they can't do 140 for miles on end ha ha. Those were the days, no seat belts but helmets the cops used.
 
340mopar said:
These speed charts are only theoretical speeds, they won't take into account wind, tire resistance, etc. which is usually what tops out a car. Cars usually run out of HP before they run out of RPM.

This is what is limiting the speed of my Crossfire to 154mph. It runs out of HP before the PRM hits redline.

Granted your 408 will have more HP than my Crossfire but you are trying to push a brick through the air while I am pushing a car with a lower drag coefficient.


Chuck
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Your forgetting that your crossfire has a OD 5th gear and our older cars only have a 1/1 4th gear. leave your crossfire in 4th gear then you will tach it out. Even my stock 340 Dart with 3.23's will run out of RPM before it runs out of HP. Now if it had a 5th gear that would be different.
 
1wild&crazyguy said:
you can go death speed if ya don't let out of it..

I've buried the speed-o many times with my 340 and 410

btw corvettes suck farts
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I'm a Mopar Guy, but would be more than happy to let you suck a fart of of my Corvette....that is if you could get close enough.....gotta be real carefull with those kind of statements....lol

Orlando2009NHRADiv-21.jpg


Rickster
 
Burntorange70 said:
Your forgetting that your crossfire has a OD 5th gear and our older cars only have a 1/1 4th gear. leave your crossfire in 4th gear then you will tach it out. Even my stock 340 Dart with 3.23's will run out of RPM before it runs out of HP. Now if it had a 5th gear that would be different.
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True, why some build a motor for high rpm's. Then shorter stroke motors can safely rev higher than a 4 inch stroke motor, at least its cheaper to build a 7,500 rpm 3.31 stroke motor than one with a 4 inch stroke.

Listen to these guys who are talking about not losing control. It can happen and at 45 mph you might get bang up a bit, at 70 mph you might be in hospital for over week and at 100 mph+ your car and life is all over with.

Why today few if any new cars can do an honest 140 / at least in a 1/2 mile. Brakes are better but brakes don't help the car stick to the road and brakes don't slow the car down when the car is skidding out of control, brakes will filp the car over.
 
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