What should I expect from 450hp?

-
Backally

Backally

FABO Gold Member
FABO Gold Member
Joined
Sep 4, 2011
Messages
627
Reaction score
392
Location
Wisconsin
Got a 408 a 3350# Duster, estimate 450-475hp. This is a street only car--4spd, 3:23 gears with 245/60-15 BF Goodrich's. I got a Holley sniper so can look at datalogs. If I am in first gear rolling along at about 2000rpm and mash it, it takes about 1.75 seconds to get to 6000rpm. Only traction addition is the pinion snubber, but seems like it hooks up, tires aren't squealing or leaving black marks . Just seems to me it should be quicker or am I expecting to much?

Sniper with WOT a/f at 12.8, Edelbrock rpm heads & intake. 235/239 @ .050, 535/550 lift. 9.5 compression
 
Torque converter stall? Oops 4spd nevermind.
Take it to the track. Sometimes seat of the pants isn't all
 
Last edited:
Backally said:
Got a 408 a 3350# Duster, estimate 450-475hp. This is a street only car--4spd, 3:23 gears with 245/60-15 BF Goodrich's. I got a Holley sniper so can look at datalogs. If I am in first gear rolling along at about 2000rpm and mash it, it takes about 1.75 seconds to get to 6000rpm. Only traction addition is the pinion snubber, but seems like it hooks up, tires aren't squealing or leaving black marks . Just seems to me it should be quicker or am I expecting to much?

Sniper with WOT a/f at 12.8, Edelbrock rpm heads & intake. 235/239 @ .050, 535/550 lift. 9.5 compression
Click to expand...

Dude, you have a camshaft in that thing that begs for 3.91 or 4.10 gears and you're wondering why it's a little soggy on the bottom? I know.....let me guess. You're not gonna put 3.91s or 4.10s in it. That thing would take off like a Saturn V rocket if you did.
 
So hard to make a judgement call off of the info you provided, but usually a stroker with aluminum heads will make quick work out of 245/60 normal street tire - as in gone up in smoke!! in more than just 1st gear.
 
[QUOTE=" I know.....let me guess. You're not gonna put 3.91s or 4.10s in it. [/QUOTE]

I do have a 489 carrier with 3:73’s, had these in with my 340. I was under the impression the extra torque of the 408 would more than make up for the gear change but not sure that it feels like it. I do a fair amount of highway driving
 
Backally said:
Got a 408 a 3350# Duster, estimate 450-475hp. This is a street only car--4spd, 3:23 gears with 245/60-15 BF Goodrich's. I got a Holley sniper so can look at datalogs. If I am in first gear rolling along at about 2000rpm and mash it, it takes about 1.75 seconds to get to 6000rpm. Only traction addition is the pinion snubber, but seems like it hooks up, tires aren't squealing or leaving black marks . Just seems to me it should be quicker or am I expecting to much?

Sniper with WOT a/f at 12.8, Edelbrock rpm heads & intake. 235/239 @ .050, 535/550 lift. 9.5 compression
Click to expand...


6000 rpm is about 60 mph in 1st gear so your going from 10 mph to 60 mph in less than 2 seconds and that ain't quick, pretty sure it's taking longer than 1.75 seconds :)
 
Backally said:
I do have a 489 carrier with 3:73’s, had these in with my 340. I was under the impression the extra torque of the 408 would more than make up for the gear change but not sure that it feels like it. I do a fair amount of highway driving
Click to expand...

3.23 with a 408 is similar torque to the ground to a 3.55 geared 360, basically a 408 allows you to run one gear step higher than you would with a similar 360.

or about two steps with a 340, does it pull as hard as your 340 with 3.73 gears?
 
Here's one.......is your clutch slipping ?? I am of the opinion that you should be desintegrating your tires when you mat the gas, 3.23's are not too tall for that to happen.

Decades ago I did a Pontiac 455 in a 77 Trans -Am, rear gears were 3.08, maybe 2.90 something, also a 4 spd car. At idle in first, mat the gas and tires went up in smoke instantly, or if from idle, you layed into the gas slowly to the floor, at about 1500 rpm the the tires would brake loose and up in smoke. I always ran out road before the tires would stop spinning, just before the 3-4 shift.
 
Keep the gears you have and likely make it from point “a” to wherever point “b” is sooner than you would going to a much higher numerically gear. Unless you can make the tires stick or settle for rolling runs (which is what I do to thwart tires churning) of course......hmmm. That’s be my take
 
it's your cam.My friend built a 408 with a small cam and 3.23 gears and could get massive tire spin in three gears.
He also has a 396 camaro with 3.31 gears.Has raced them side by side and his 408 dart walks away from the camaro until about 80 mph and then the 396 camaro runs him down and pulls away from the dart
With gears i think you would have a nice quarter mile performer!
 
ir3333 said:
it's your cam.My friend built a 408 with a small cam and 3.23 gears and could get massive tire spin in three gears.
He also has a 396 camaro with 3.31 gears.Has raced them side by side and his 408 dart walks away from the camaro until about 80 mph and then the 396 camaro runs him down and pulls away from the dart
With gears i think you would have a nice quarter mile performer!
Click to expand...
Not the cam. That is an entry level cam for a 408.
 
273 said:
6000 rpm is about 60 mph in 1st gear so your going from 10 mph to 60 mph in less than 2 seconds and that ain't quick, pretty sure it's taking longer than 1.75 seconds :)
Click to expand...

never though of it like that. I have to pedal it at 6k and it’s still accelerating


JBurch said:
Here's one.......is your clutch slipping ??.
Click to expand...

no, clutch feels solid, and don’t smell burning clutch

thanks guys, wasn’t sure if it was performing as it should but sounds like it is. I may stick those 3:73’s in for when I’m staying around town
 
273 said:
3.23 with a 408 is similar torque to the ground to a 3.55 geared 360, basically a 408 allows you to run one gear step higher than you would with a similar 360.

or about two steps with a 340, does it pull as hard as your 340 with 3.73 gears?
Click to expand...

I’d say so, it was a 380hp 340 so ran pretty good with the 3:73’s
 
I have a 410 stroker with a cam of similar specs with 3.91 gears , 5 speed manual and 255x17 rear tyres and at any time I put my foot into it in second gear it instantly breaks traction and wheel spins at six grand. My car has caltracs which work good and does 11.4 @ 119.5 mph in the qtr on small slicks.Sounds like you need some tunning?
 
273 said:
3.23 with a 408 is similar torque to the ground to a 3.55 geared 360, basically a 408 allows you to run one gear step higher than you would with a similar 360.

or about two steps with a 340, does it pull as hard as your 340 with 3.73 gears?
Click to expand...

sorry, not true. There is basically no difference between a 3.23 and 3.55 gear. Very little. Barely noticable
There is a big difference between a 3.58 and 4inch stroker crank. Real big. Very noticable
 
B3422w5 said:
sorry, not true. There is basically no difference between a 3.23 and 3.55 gear. Very little. Barely noticable
There is a big difference between a 3.58 and 4inch stroker crank. Real big. Very noticable
Click to expand...

408/500 lbs-ft 1st gear 2.45 x 3.23 x 500 lbs-ft = 3957 lbs-ft
360/440 lbs-ft 1st gear 2.45 x 3.55 x 440 lbs-ft = 3827 lbs-ft
340/415 lbs-ft 1st gear 2.45 x 3.73 x 415 lbs-ft = 3792 lbs-ft
 
Last edited:
B3422w5 said:
Drive those different combos you mention.
Real world
Click to expand...

Not exactly I went with an achievable 1.23 ish lbs-ft per cid. The dyno for a crate 380hp/360 makes 440 lbs-ft, just looked at a couple of 318 builds were doing 385-405 lbs-ft A 340 411 lbs-ft, lot of 408 don't even hit 500 lbs-ft some do better, nothing out of the realm of possibility, if they made 3.66 and 3..88 gears all three of those would come out the same.

Just was showing the gear has just as much as the stroke when it comes to power to the tire.
 
B3422w5 said:
sorry, not true. There is basically no difference between a 3.23 and 3.55 gear. Very little. Barely noticable
There is a big difference between a 3.58 and 4inch stroker crank. Real big. Very noticable
Click to expand...

it's not quite that simple...I remember a comparison Dulcich did with an identically built 408 and 360.Can't remember exactly but i think they used a stout cam and stock heads.There was very little difference between the 2 engines.
 
Need to verify it’s not spinning the BFG T/A radials.

OP has had issues with the Sniper FI.

Backally, have you run this motor with a carb.

Was this motor dyno’d with the Sniper? If not, did you drive it with the dyno carb?
 
lo gear (3.23), tall tire and long duration cam can kill bottom end on big blocks too!.
 
Backally said:
[QUOTE=" I know.....let me guess. You're not gonna put 3.91s or 4.10s in it.
Click to expand...

I do have a 489 carrier with 3:73’s, had these in with my 340. I was under the impression the extra torque of the 408 would more than make up for the gear change but not sure that it feels like it. I do a fair amount of highway driving[/QUOTE]

Sometimes that's the case.......and even though I said that, it might be worth your while to make SURE your tune is top notch. normally, strokers or larger cube engines kinda "don't care much" about gear ratio. So I think before I went drastic enough as a gear change, I would make sure everything else was right. That said, that 3.73 sure would wake it up either way.
 
You must log in or register to reply here.
-

Back
Top