Author Topic: Word of Thanks: 'A Good Day on the Dyno'  (Read 3183 times)

Offline motorvation2go

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Word of Thanks: 'A Good Day on the Dyno'
« on: December 19, 2011, 05:35:51 PM »
Hello to all,
   I'd like to thank Cliff for all of the great info provided in his book, and also for that which can [so easily] be gained through this forum!
Today was the day of reckoning for my lil' ol' Chivvy' :) 406.
She got strapped to the dyno with her 'new' Q-Jet.
This is strictly a street motor, and I was more than happy to sacrifice a few ponies at the very 'top' for crisp bottom end throttle response and midrange grunt.
With this goal in mind, I ran a Q-Jet Performer RPM fully divided(!) side to side (but open front to rear).
!.5" total spacer height (again totally divided)
800 Q-Jet (originally from a 1980 truck)
I do confess to having gone overboard with a bunch of mods to this carb, but suspect that a stock one (properly built) would have showed nearly as good.
I just like playing with the fine details, thats all.  ;D
A quick engine rundown: 10.2 CR, 'off the shelf' Comp Cams 274S flat tappet, AFR 195 Street Eliminator heads, and a fair bit of overall attention to the [aformentioned] 'detail stuff'.
Cutting to the chase: Motor made 492 HP@ 5700 rpm with torque peaking 522 lb/ft@ 4000.
Lowest RPM recorded during pull was 3489 rpm with the motor already making 506 lb/ft.
BSFC .397 to .420 'ish' throughout pull.
Motor is happiest at 34 degrees total (within 1 hp of 36 total)
The thing starts just unbelievably quick. I mean hit the key on the dyno console ... and instantly(!) it's running.
Even had it idling happily at 500 rpm... not where I'll run it, But Man!!!  8)
The graphed computer readout was incredibly smooth... none(!) of that sawtooth stuff to be found.
The shop where all of this took place today is run by two good friends (both multiple time NHRA record holders in both Superstock and ProComp).
They confided *that in their honest opinion, the motor was making a little better power than it had (~ two years ago) with a near $1000.00 custom built Holley then in place atop a Performer RPM w/1" open spacer and reworked plenum etc.
The 'big' number at that time was 503.7 HP peak, but(!) recent changes to the dyno setup have proven to give lower numbers than previously tested-and [now] recently retested 'known and freshened up' engines.
They were both highly impressed with the Q-Jet's performance.
And these guys don't impress easily, believe me.
Should quickly note that torque production has moved another 400 to 500 rpm down the rpm scale (widened!) with no sacrifice towards the top.
If you think that maybe I'm happy with the days events... you're not mistaken.  8)
So once again, please allow me to express my sincere thanks to Cliff for helping make this good day happen.
Cheers!


 

Offline Cliff Ruggles

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Re: Word of Thanks: 'A Good Day on the Dyno'
« Reply #1 on: December 20, 2011, 02:07:42 AM »
Good news!  Stout numbers from the 406, especially having over 500 ft lbs torque available low in the rpm range.  Have fun trying to hook it up!.....Cliff

Offline jamesF

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Re: Word of Thanks: 'A Good Day on the Dyno'
« Reply #2 on: December 30, 2011, 06:48:42 PM »
Wow! Must be a proud papa. That is great. Is that a Factory Block or an aftermarket?

Offline Ethan1

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Re: Word of Thanks: 'A Good Day on the Dyno'
« Reply #3 on: December 31, 2011, 06:28:44 PM »
 Sure wish my 406sbc made that much in my Chevelle! That is awesome! ;D
Ethan

1972 Chevelle

(oo______oo)

Offline Frank400

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Re: Word of Thanks: 'A Good Day on the Dyno'
« Reply #4 on: January 01, 2012, 05:20:13 PM »
can you elaborate a bit about going a bit overboard with carb mods ?

Offline motorvation2go

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Re: Word of Thanks: 'A Good Day on the Dyno'
« Reply #5 on: January 09, 2012, 07:31:20 PM »
Hi guys,
    Sorry for not having responded earlier, but there was a problem with [me] being unable to log in for the past two weeks.
James to the rescue! Thanks for your help James.

The block is a factory 2 bolt block.
Using ARP main studs, half fill of Hard Blok.
Bored and subsequently honed with deck plates.
Internally balanced (two slugs mallory metal) scat ultralight crank.
6" rods.
Fabbed oil pan with full kick out and directional screening for windage control.
The carb was the focus of a lot of detail stuff.
Perhaps all of it unnecessary, but heck I just plain love doing the work.
Quick rundown: choke eliminated, shaft holes plugged.
All sharp [leading] edges in airhorn radiused, irregularities smoothed and blended.
Thinned throttle shafts, button head screws, knife edged throttle butterflies, both vertical vanes and 'bumps' (800cfm carb) removed from primary venturis.
Cleaned up booster rings etc.
Thinned fuel transfer passage from main body to fuel discharge point in booster

A lot of painstaking die grinder, dremel, and hand work with fine enery strips (in boosters) etc.
Made screw in idle tubes (with 10-32 set screws)  for easier removal and replacement.
Standard stuff such as fuel well plugs replaced with screw in variety etc
Relocated POE to under air valve.

I'm missing a bunch of stuff, but kinda rushing as I just lost an entire (over an hours writing) answer I tried to post previous to this (I'm slow and went over the time limit?)

If you have any further questions, I'd be more than happy to help out.
I have a number of detailed pictures of the carb work, but I'm hopelessly incompetent with computers and how to post them etc.

Probably is a way to PM here? If so I'd be happy answer anyone who wishes to see some detailed
pictures.
Cheers
« Last Edit: January 11, 2012, 03:02:21 PM by jamesF »

Offline jamesF

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Re: Word of Thanks: 'A Good Day on the Dyno'
« Reply #6 on: January 11, 2012, 03:00:27 PM »
You can post pics here and attach them to your post. See the Posting pictures thread in the "lobby"  click here  --->  http://cliffshighperformance.dreamhosters.com/simplemachinesforum/index.php?topic=326.0

Or let me know, I can help,
James