Chassis dyno power vs. drivability - Team Camaro Tech
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post #1 of 14 (permalink) Old Mar 6th, 10, 05:43 PM Thread Starter
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Mike
 
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Chassis dyno power vs. drivability

Ok here goes, put my '67 on the dyno today--results 216hp/276tq. Car is a 327(factory 275hp 4bbl) muncie 4spd 10bolt w/3.73. Engine is .030 over, comp cam#12-238-2(I.462lift/E.469 lift), comp cams "roller tip" rockers, Edelbrock Perf RPM air gap intake, 1406 4bbl carb, stock exhaust manifolds. Question is car does not drive very well-- not a smooth power curve on the street seems resticted/choppy acceleration-- that & I was hopeing for a higher power #. Would a set of headers w/larger exhaust make a large difference? Should this setup be making more power? Car was WAY more fun to drive with my old Holley carb/Crower cam. Help/Suggestions?
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post #2 of 14 (permalink) Old Mar 7th, 10, 08:54 PM
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Re: Chassis dyno power vs. drivability

Quote:
Originally Posted by toolfan View Post
Car was WAY more fun to drive with my old Holley carb/Crower cam. Help/Suggestions?
you have some tuning issues with the new combo.

did they tune on the dyno?
How many pulls did they do?
do you have a graph (HP / Tq / AFR vs rpm) that you can post?





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post #3 of 14 (permalink) Old Mar 7th, 10, 11:03 PM
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Re: Chassis dyno power vs. drivability

It's all in the tune.
Did the 275's come with hump heads?
Put a vacuum gauge on the motor and see where the vacuum is at, I noticed the 327's respond pretty drastically to cam changed, they like vacuum.
When I put big heads and a big cam in my .040" 327 the vaccum was and is low and has no velocity. It doesn't build power til 3k and it's just something you have to live with.
Rear gears and stall (if an auto) will make a huge diff. in how the car drives.
With the 4spd your limited on gear selection if you mainly drive on the street.
I know I have to do alot of clutch slipping with the factory 3.08's.

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post #4 of 14 (permalink) Old Mar 8th, 10, 07:52 AM Thread Starter
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Re: Chassis dyno power vs. drivability

Did about 6 pulls. Yes tuned as well, initial timing 11deg/total timing 28deg. I can try to post the dyno result sheet. Forgot to mention stock iron heads as well. The AFR's looked real good nice & flat.
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post #5 of 14 (permalink) Old Mar 8th, 10, 08:27 AM
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Re: Chassis dyno power vs. drivability

Quote:
Originally Posted by toolfan View Post
Yes tuned as well, initial timing 11deg/total timing 28deg.
You're leaving some power and torque on the table with total timing of only 28*; setting it at 34*-36* should show a noticeable improvement.


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post #6 of 14 (permalink) Old Mar 8th, 10, 09:15 AM
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Re: Chassis dyno power vs. drivability

curious... what were the specs on the old crower cam?
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post #7 of 14 (permalink) Old Mar 8th, 10, 10:47 AM
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Re: Chassis dyno power vs. drivability

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Originally Posted by JohnZ View Post
You're leaving some power and torque on the table with total timing of only 28*; setting it at 34*-36* should show a noticeable improvement.

agree, and more initial wouldn't hurt either.
why did they set it so conservative?





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post #8 of 14 (permalink) Old Mar 8th, 10, 07:33 PM
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Steiner
 
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Re: Chassis dyno power vs. drivability

Agree on the timing. Also experiment with some lighter weight springs.

One thing to check if you haven't already (since you changed out the carb) is to have someone mash the pedal to the floor while you look down the carb to make sure the throttle plates are opening all the way. Engine off, of course.

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post #9 of 14 (permalink) Old Mar 8th, 10, 07:38 PM Thread Starter
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Re: Chassis dyno power vs. drivability

I was actually doing alot of tuning. AFR's were a solid 14.8(yes abit lean but need to pass emmissions). the engine liked more timing but it was running out of fuel. Upgrading to a elec fuel pump this week as well as changing jets, metering rods/springs, & I have a set of headers coming as well. As for cams the Crower was a I 258 deg/lift.414-- E 264 deg/.417
(current) Comp Cams I 262 deg/.462 lift -- E 270 deg/.469 lift. At idle engine is pulling a solid 14-15." vacuum.
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post #10 of 14 (permalink) Old Mar 8th, 10, 07:46 PM Thread Starter
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Mike
 
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Re: Chassis dyno power vs. drivability

Crap, sorry forgot to mention MSD 6AL & billet dist. Changing springs are you refering to timing springs or carb/metering springs? On the old setup I was running 36* total timing -- I'll try giving it more when I get the fuel curve a bit better. Oh ya not running a vac advance as well(ran better on old setup not hooked up). Thx again for help/suggestions.
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post #11 of 14 (permalink) Old Mar 8th, 10, 07:55 PM
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Re: Chassis dyno power vs. drivability

The advance springs in the distributor. You'll notice a good bit of power just getting your total timing back up around 36*.

Was your AFR at part throttle or full throttle? I'd think you'd want to see around 12.5 to 13 at full bore.

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'02 Z/28 vert-stock-sold and totaled
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post #12 of 14 (permalink) Old Mar 8th, 10, 08:29 PM Thread Starter
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Re: Chassis dyno power vs. drivability

AFR's were @ full throttle. I agree that they should be around the 12.5/13 area-- but I need to balance power/emmissions legal tune, hands are kinda tied there-trying to get it emmissions exempt. Had not thought about changing springs in dist(cause not 1 of the changes I had made). Not really looking for a "power monster" due to it being a #'s matching car just better drivability(pretty sure it has more in it than it's showing now)
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post #13 of 14 (permalink) Old Mar 8th, 10, 09:04 PM
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Steiner
 
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Re: Chassis dyno power vs. drivability

Your emissions testing should be based on part throttle which is where you want it to be 14.7:1 or thereabouts. If you are tuning it to lean out that much at full throttle that would explain your choppy feel as it is running extremely lean now at part throttle.

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'02 Z/28 vert-stock-sold and totaled
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post #14 of 14 (permalink) Old Mar 9th, 10, 12:39 AM
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AJ
 
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Re: Chassis dyno power vs. drivability

Try running full manifold vacuum advance.
With 5-6" of vacuum my setup didn't run too well with it hooked up, idle sucked, but adjusting the advance can helps. It loves every bit of the full manifold advance.
I felt an increase in off the line performance and drive ability when I switched.

The only Mustang I'd ever own is a Fender.

'68 333" Camaro
'14 5.0 Mustang
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