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PostPosted: Mon Dec 18, 2017 4:09 pm 
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4 BBL ''Hyper-Pak''
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Joined: Tue May 18, 2010 11:24 am
Posts: 45
Location: Philly, PA
Car Model: 1969 Plymouth Valiant 225 \6
I know that a lot of hp ratings were "manipulated" in the 60s and 70s because of insurance. My particular single barrel says 160hp and 220tq. Does anyone have actual data on what a slant really put out? Single barrel, 2 or 4? Any dyno results? Did they just "adjust" the hp ratings on muscle cars and not all factory cars, or was it industry-wide? Just curious. Thanks for all of the help in the past. You guys are awesome.


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PostPosted: Mon Dec 18, 2017 5:23 pm 
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Joined: Thu Oct 31, 2002 5:39 pm
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Location: North America
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1969Valiant wrote:
My particular single barrel says 160hp and 220tq.


Where are you seeing this? That was never a claimed rating for any 1bbl Slant-6. The export/Australia 2bbl Slant-6 setup of '67-'75 had a claimed/published rating of 160 BHP.

See here for more info on the factory's claimed numbers.

Quote:
Does anyone have actual data on what a slant really put out?


Here are more realistic numbers from a 1961 225 engine, removed from a new Dodge Lancer, put through a 50-hour break-in, meticulously checked and set to factory specs, and put through well-documented tests in March of 1961. These tests were not done by or for Chrysler; they were done in General Motors' engine engineering department for competitive analysis.

Gross output (air cleaner removed)
Maximum BHP 126.5 @ 3800 rpm
Maximum Brake Torque 210.7 lb·ft @ 1600 rpm

Maximum output (just shy of detonation)
Maximum BHP 115.9 @ 3800 rpm
Maximum Brake Torque 196.9 lb·ft @ 1400 rpm

As-Installed Output
Maximum BHP: 104.5 @ 3800 rpm
Maximum Brake Torque: 189.4 lb·ft @ 1400 rpm

These numbers are notable for a bunch of reasons: they don't conveniently end in nice, tidy, round, advertising-friendly 0s and 5s like Chrysler's 145 (hp) and 215 (torque) figures. The gross BHP figure falls well shy of the published claim. It does, however, match up very well with the "127" rating Chrysler published for the industrial 225 configured and equipped just about identically to the passenger car engine in all the ways that mattered to output. That looks a lot like it was wisely decided that the only real purpose of a horsepower number on a passenger car is to sell the car, while people specifying industrial engines have a genuine need to know what they're actually getting.

There are power and torque plots for various-year 1bbl and 2bbl Slant-6s, which may or may not be less or more than tweaked graphical representations of bogus numerical claims, in "A History of Chrysler Corporation's Slant-Six Engine", which may or may not still be available from Chrysler Historical.

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Last edited by SlantSixDan on Thu May 28, 2020 4:41 pm, edited 1 time in total.

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PostPosted: Mon Dec 18, 2017 5:54 pm 
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Joined: Thu Oct 17, 2002 7:27 pm
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Location: Park Forest, Illinoisy
Car Model: 68 Valiant
When I started racing my stock '76 Duster the mph translated to about 87 horse at the wheels, so roughly 100 at the crank. I've seen some stock ones do better, but that is fairly average.

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PostPosted: Mon Dec 18, 2017 10:51 pm 
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Joined: Sat Nov 02, 2002 7:52 pm
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Location: San Antonio, Texas
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That's why I'd like the 225 in my D150 to make 160 hp.


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PostPosted: Tue Dec 19, 2017 6:29 am 
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Joined: Mon Oct 21, 2002 11:08 am
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Location: Blacksburg, VA
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I guess now I can say my turbo car makes about 3.5X the factory HP. Shooting for 4X this year... It also gets about 30% better MPG than when it was stock.

Lou

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PostPosted: Tue Dec 19, 2017 6:38 am 
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Turbo EFI
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Joined: Mon Jan 12, 2015 5:55 am
Posts: 1086
Location: Brightwood, VA
Car Model: 1965 Plymouth Belvedere I
Quote:
There are power and torque plots for various-year 1bbl and 2bbl Slant-6s, which may or may not be less or more than tweaked graphical representations of bogus numerical claims, in "A History of Chrysler Corporation's Slant-Six Engine", which may or may not still be available from Chrysler Historical.


Dan, in a round-about way, you may have nailed it-more or less.

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PostPosted: Wed Dec 20, 2017 6:09 pm 
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Joined: Thu Jan 05, 2006 12:53 pm
Posts: 62
Location: Lewisburg, PA
Car Model: 1969 Dart 340, 1975 Dart 225, 1967 Dart 225
I have run two slant six Darts several times on a Mustang chassis dyno. The first slant six is in my employer's 1967 Dodge Dart GT. It is an all original 23K-mile car with one non-stock component. We added a Mopar Performance electronic ignition distributor and module for better driveability. The second Dart is mine, a 1975 Dart Swinger that is all stock including all the emissions components.

The 1967 Dart's output was 77 hp at 3600 RPM and 124 lb-ft of torque at 2550 RPM.
The 1975 Dart's output was 78 hp at 3550 RPM and 127 lb-ft of torque at 2600 RPM.

The baselines were established with three runs within 1% of each other, and the SAE J607 weather correction standard.

Both engines really perked up when the initial timing was increased and the centrifugal timing was reduced.

1967 Dart dyno run
https://www.bing.com/videos/search?q=ch ... ORM=VDRVRV

1975 Dart dyno run
https://www.bing.com/videos/search?q=ch ... ORM=VDRVRV

I have done 100s of dyno runs on dozens of different parts for the slant six. If you are interested, please contact me.

Chris


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PostPosted: Wed Dec 27, 2017 7:17 am 
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Turbo EFI
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Joined: Mon Jan 12, 2015 5:55 am
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Location: Brightwood, VA
Car Model: 1965 Plymouth Belvedere I
Can you post what combination yielded the highest power on the dyno?

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PostPosted: Thu Feb 01, 2018 1:34 pm 
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4 BBL ''Hyper-Pak''
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Joined: Tue May 18, 2010 11:24 am
Posts: 45
Location: Philly, PA
Car Model: 1969 Plymouth Valiant 225 \6
Sorry it took me a while to get back to you all. Yeah, seems like it was the export version that I was looking at. Was 165, not 160HP though and I think it said 232 TQ or something. Thanks for taking the time to reply with all of the info. Hope all your slants are well. Mine is kicking ass but could use a timing adjustment, maybe some new points. Btw, how often should you replace the points? I run my car pretty hard. I've put on 30,000 since they were replaced and have done 100ph in it more than a few times. Thanks again.


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PostPosted: Thu Feb 01, 2018 3:04 pm 
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Turbo Slant 6

Joined: Sun Jul 20, 2008 10:20 am
Posts: 717
Location: St. Louis Park, MN
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Mopar Performance used to publish a magazine or newsletter. In one issue they tested a number of the parts they were selling for slant 6s at the time on 198" engine on their dyno. Stock the engine put out 111HP this would be a gross HP number at the clutch. Adding a Mopar electronic ignition raised that to 121HP for no good reason I can think of, then they added a 2 barrel carburetor similar to a super six set up and 1 5/8" headers (probably a 6 into 1 set up) and saw 152HP. Next they added a 244 degree MP cam and got 159HP, a 350 Holley raised that to 162HP. Then they added one of the MP prepared heads with oversize valves that they used to sell for 192HP and finally a 276 degree cam pushed the output up to 201HP. Nothing was said about raising the compression ratio although I think they might have had less CCs in the MP head to produce a 30HP gain. Remember this was with a 198" motor so you might be 10% or so better with a 225. Having made similar modifications to my street car and tested them on the drag strip I would say these are reasonable numbers for the modifications involved.

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