Dodge Dart Dyno day 2016

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BigBlockMopar
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Dodge Dart Dyno day 2016

Post by BigBlockMopar » Wed Aug 17, 2016 5:45 pm

3 years ago I put my car on the dyno to get a horsepower and torque number from the setup at that time.
(Stock 2-bbl carb and intake, convertor and 300A mixer).
See old topic here-> viewtopic.php?f=5&t=1482

Now, this monday I put my car on the dyno again, just to find out what the upgrade to a 4-bbl intake, a 425 carb and some more distributor-recurving has led to.
In short, it was 24 horsepower.

The first run netted 158hp, but after leaning out the overly rich max.power valve in the 425, horsepower managed to climb to 169.7 hp.


The video of the last 2 runs can be seen here;
https://www.youtube.com/watch?v=HLmhGuwjhQo

One other thing different was that I used 5w20 oil in the first Dyno-session 3 years ago, and now I was running a 10w30 + 10w40 mix.
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

storm
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Re: Dodge Dart Dyno day 2016

Post by storm » Wed Aug 17, 2016 8:22 pm

What was the flow rating on the old 2 barrel carb? The reason I ask is you may find the gain in HP is simply because of less restriction which means further adjustment of the timing may bring further increases as well.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

BigBlockMopar
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Re: Dodge Dart Dyno day 2016

Post by BigBlockMopar » Thu Aug 18, 2016 3:33 pm

Don't know the exact cfm on the stock 2-bbl carb, but it's probably somewhere around 350cfm. Which maybe is even rated at a higher vacuum-difference as well.
Put a IMPCO 300A on top of that and I think flow hurts even more.

When I changed to the 425 carb a while back I felt an immediate increase in power in the higher rpms.

I have altered the timing and curve recently and found more low and high range power in the engine. That's kinda what made me curious and let me to put the car on the dyno again.

Current timing specs are:
12.5 initial
25 mechanical in distributor.
So 37.5 total
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

storm
Posts: 566
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Dodge Dart Dyno day 2016

Post by storm » Thu Aug 18, 2016 11:00 pm

Not taking into account the type of fuel used, on a perfectly tuned (that takes into account efficient exhaust flow, timing, etc.) street car 1.5HP/cfm would net you 175 HP from a 350 cfm carb so the 318 was doing well the last time it was on the dyno. The 425 is theoretically capable of approximately 280 HP based on cfm so it is no surprise you felt a difference because you have given the engine the equivalent of 100 HP worth of extra cfm.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

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kikkegek
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Location: Netherlands, The Hague

Re: Dodge Dart Dyno day 2016

Post by kikkegek » Tue Aug 23, 2016 3:08 am

awesome video!

time to go Vapor injection!
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

BigBlockMopar
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Re: Dodge Dart Dyno day 2016

Post by BigBlockMopar » Tue Aug 23, 2016 3:07 pm

injection will be done after the engine swap.
Until that time, I will be installing a new dual 2.5" exhaust system with X-pipe, full length coated headers and Borla ProXS mufflers.
Then I will have another go at the dyno to find out how this will help the 318 breathe.

Current exhaust system is castiron manifolds, two 2.25" pipes to stock-ish mufflers. No crossover pipe.
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

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kikkegek
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Re: Dodge Dart Dyno day 2016

Post by kikkegek » Tue Aug 23, 2016 3:34 pm

sounds like a cool upgrade.

pretty curious what it will bring, besides a cool rumble ;-)
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

BigBlockMopar
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Joined: Sun Sep 02, 2007 3:29 pm
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Re: Dodge Dart Dyno day 2016

Post by BigBlockMopar » Sat Oct 15, 2016 5:50 am

I've installed the new exhaust system awhile ago.
Headers / X-pipe / Borla Pro-XS, all mandrell bent 2.5" diameter tubing through the tailpipes.
Bit overkill for the current 318ci engine, but will fit a bit better with the planned 360ci later on.

I've already felt the engine accelerates easier through the mid/higher rpm's, from 2500 rpm and up.
Also think engine-vacuum is about 1-2" higher during steady highway cruising.

Will do some more 'butt-tuning' on the engine first and then make a new appointment on the dyno again.

Image

Image
Last edited by BigBlockMopar on Sun Sep 03, 2017 6:58 am, edited 1 time in total.
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

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kikkegek
Posts: 373
Joined: Thu Nov 17, 2011 2:12 pm
Location: Netherlands, The Hague

Re: Dodge Dart Dyno day 2016

Post by kikkegek » Sat Oct 15, 2016 6:54 am

wow, exhaust system looks killer. curious about the dyno results
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

BigBlockMopar
Posts: 346
Joined: Sun Sep 02, 2007 3:29 pm
Location: Netherlands
Contact:

Re: Dodge Dart Dyno day 2016

Post by BigBlockMopar » Sun Nov 13, 2016 5:53 pm

Having driven around for awhile with the complete new exhaust system, I dove into the distributor again to seek some more improvements.
I decided to do some more recurving of the ignition, as I wasn't quite happy with low rpm power yet.
I was running about 15-17° initial advance before, with a somewhat normal/medium fast curve and high mechanical advance well into the high 30s.
Tuning back to 10° initial gave back some low rpm torque and less throttle opening needed for the same amount of torque/power. A retuned vacuum advance made up for the lower initial advance.

Now after another recurve I went back to 10° initial, 22° mechanical and a little faster curve;
10° initial @ 650rpm
26° @ 1500rpm
28° @ 2000rpm
32° @ 3000rpm

24° init+va idle in Neutral (650rpm) / 16° init+va idle in Drive (550rpm).

The acceleration is currently the best I've ever felt in the engine. Low rpm, mid range and high rpm power are all very good.

Unfortunatly the chassis dyno I usually visit is moving to a new location and won't be operational somewhere in January again. I very much would like some dyno-time right now to further finetune the ignition timing, but I guess I have to wait.

I'll be keeping a more close eye on the mileage now as I do believe this new setting should have a noticable effect on my (still lousy) average 11 MPG.
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

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kikkegek
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Re: Dodge Dart Dyno day 2016

Post by kikkegek » Mon Nov 14, 2016 2:28 am

cool, great update.
...but like you said, only way to really find out is by dyno or gas-mileage...
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

storm
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Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Dodge Dart Dyno day 2016

Post by storm » Mon Nov 14, 2016 2:11 pm

That is terrible mileage, to me it is anyway. 318s are heavy drinkers but a well built and tuned one should get much better mileage than that.
What's your idle vacuum?
Are you able to do any data logging?
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

BigBlockMopar
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Re: Dodge Dart Dyno day 2016

Post by BigBlockMopar » Mon Nov 14, 2016 4:05 pm

No datalogging.
The milage sucks for me to. Given all the time I've put into getting mpg to improve, compared to others locally, who spend no-time and still get similar numbers.

The engine is pretty much stock.
I always thought it was the stock '73 engine, but is a mid '80s engine with slightly newer heads.


Idle vacuum is very stable and healthy, around 23 @ 650 neutral. Around 21" @ 550rpm in Drive.
Last edited by BigBlockMopar on Tue Nov 15, 2016 4:28 pm, edited 2 times in total.
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

storm
Posts: 566
Joined: Wed Jan 10, 2007 10:10 pm
Location: NSW, Australia

Re: Dodge Dart Dyno day 2016

Post by storm » Mon Nov 14, 2016 5:37 pm

You sig says you car is '73 Dodge Dart - 318ci - IMPCO E vaporizer / 425 mixer - A518-OD trans - 3.55 gears - 225/50/17" tires.
Assuming my calculations are correct you should be doing approximately 2000 RPM at 100 kmh in overdrive. Do you know what vacuum the engine is pulling at that speed?
What speed do you normally sit at while driving? What vacuum is the engine pulling at that speed when cruising?
If you could map out rpm/speed/vacuum for when the car is cruising at different speeds we may be able to work out a better timing map at different cruise speeds which will get you in some sort of ball park before you can get back to the dyno.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

BigBlockMopar
Posts: 346
Joined: Sun Sep 02, 2007 3:29 pm
Location: Netherlands
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Re: Dodge Dart Dyno day 2016

Post by BigBlockMopar » Tue Nov 15, 2016 4:46 pm

I believe I'm running a 215 tire at the moment so rpms are a tad higher at 100 km/h at around 2100rpm.
The engine has around 17" of vacuum at these speeds. Since the recent recurve I tend to see 18" and sometimes close to 19" during 'steady' highway cruising.
I usually drive at speedlimit+10 km, or 20.
At higher highway speeds the vacuum is around 16-17".

But my car doesn't see long highway-times. Usually 2-3 minutes at the most before I take an offramp again.
I encounter a mixed driving in 50, 80 and 100 km/hr zones.

Longer highway trips usually result in 15mpg.
Only once I managed to get 17mpg during a day of driving around the country, but this was with a different (non-overdrive) transmission and 3.23 gears, but still with an untuned engine (very lean) adjustment. Max speed at that time was 90-95 km/h because going over that speed made the engine run hot (restrictive radiator).
https://www.bigblockmopar.com
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

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