Back from the Dyno!!

[Mac VABCH]

Today was a good day as I have finally finished installing and breaking in the new motor from Keith Craft. The motor is a 8.2" deck Dart big bore block 363 ci, AFR 205 heads with 13/1 CR. The guys at Dyno Tuned Performance in Virginia Beach, VA where able the get 490 HP @ 6300 RPM and 450 LBs torque @ 5200 at the wheels. Torque is over 420 by 2800 RPM. This is with the stock headers and side pipes. Any suggestions on headers? I am looking for at least 1 3/4" primary tube and 3.5" flow through mufflers. If you are in the market for a motor suggestion Keith Craft has my vote... Now I just have to learn to drive it all over again as it has more the 150 wheel HP on tap!

[vector1]

wow macvabch that is good, that much pwr down low and lightwt clutch is gonna be tough.

i have a header design program that will tell you what size exhaust pipe and collectors work best that is pretty accurate.

the program needs:

ve %, bore size, stroke, rod length, peak hp rpm, comp ratio, valve head diameters, valve lifts, dur. @ .050, degreed intake and exhaust centerline, lobe center angle, and the length of exhaust port from valve face to manifold mounting surface centerline.

if you post this i'll input and send you the data.

good luck.

--- Single Primary Pipe Specs --- for 406.268 CID from 4600 to 7100 RPM
Diameter= 1.817 to 1.942 Length= 29.7 to 32.5 inches long
--- 2-Step Primary Pipe Specs ---
1st Dia. inches= 1.817 Length= 14.9 to 16.3
2nd Dia. inches= 1.942 Length= 14.9 to 16.3
--- 3-Step Primary Pipe Specs ---
1st Dia. inches= 1.817 Length= 9.9 to 10.8
2nd Dia. inches= 1.942 Length= 9.9 to 10.8
3rd Dia. inches= 2.067 Length= 9.9 to 10.8

--- Header Collector Specs (Conventional Straight Tube) ---
Diameter= 3.576 Tuned Lengths= 17.1 best and 8.6 or 34.2

--- Header Collector Specs (Megaphone or Diffuser Cone Shape) ---
Diameter= 3.076 taper to 3.576 Megaphone/Diffuser Length= 17.1 inches

H-Pipe= 17.1 X-Pipe= 68.4 distance behind end of Primary Tube ends

-- Total Exhaust System Tuned Lengths (Primary ends to TailPipe end) --
Best HP/TQ Tuned Collector Lengths= 17.1 , 34.2 , 68.4 , 136.8 inches long

Worst HP/TQ Loss Collector Lengths= 25.7 , 51.3 , 102.6 , 205.3 inches long

Note=> measured from where the Primary Pipes end inside the Collector to
the point the tailpipe exits into the atmosphere.

Note-> all Pipe Diameters are OD and based-off .0625 inch Pipe thickness

---- Primary Pipe's Harmonics ----
1st Harmonic = 131.0 inches long ... typically never used
2nd Harmonic = 49.7 inches long ... longest recommended
3rd Harmonic = 29.7 inches long ... highly recommended , best Torque Curve
4th Harmonic = 20.7 inches long ... shortest recommended
5th Harmonic = 15.6 inches long ... typically never used
6th Harmonic = 12.2 inches long ... typically never used
7th Harmonic = 9.9 inches long ... typically never used
8th Harmonic = 8.2 inches long ... typically never used

---- Collector's Harmonics (includes Intermediate, Muffler , TailPipe) ----
1st Harmonic = 136.8 inches long ... longest with Mufflers and TailPipes
2nd Harmonic = 68.4 inches long ... longest recommended with Mufflers
3rd Harmonic = 34.2 inches long ... more bottom-end Torque
4th Harmonic = 17.1 inches long ... highly recommended , best Torque Curve
5th Harmonic = 8.6 inches long ... reduced Torque , more top-end HP sometimes
6th Harmonic = 4.3 inches long ... reduced Torque , not recommended

looks something like this.

[Tim Brewer]

It would be easier to just get your headers from Backdraft. Also, 13/1 CR ? Is that what you wanted? You're going to have to run race gas with that engine..big hassel...big $$.

[Mac VABCH]

Yes I did want 13/1 CR as this is a track only car. It will have a strick diet of VP 112. We did the tune with a mix of 112 and 110 (A/F @ 12.5) so in the summer months when running 112 I shouldn't have any pre detonation issues. The clutch is a Quarter Master 7.25 w/ a button flywheel and AOD ring gear for the starter. The whole clutch,flywheel and ring gear is just 17.2 lbs and is taking some time to get use to. I guess I have to buy that winch now to get it in the trailer without crashing throught the front...

Vector 1,

I will get the info and send you a PM...thanks for the help...Mac

[sllib]

Mac;
I'm getting close to that dyno pull myself. When you get a chance I'd like to talk to you about it and, maybe, offer some thoughts on headers. Please PM me with a contact number.
Bill Stradtner