Author Topic: Lykins Motorsports 428CJ  (Read 8816 times)

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gt350hr

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Re: 428CJ
« Reply #15 on: August 08, 2018, 03:57:48 PM »
   Jay,
      Your results show the 85 lb iron intake is worth a few HP too. "Back in the day" , Doug's or Jardine's were worth a couple of tenths when we installed them on stock CJ's. There was a pretty good Erson cam ( hydraulic) that was more like Brent's hydraulic roller that most of the guys used and it got the cars into the 11's with a 4.30 or 4.57 gear.
       Randy

machoneman

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Re: 428CJ
« Reply #16 on: August 08, 2018, 06:20:27 PM »
Very cool Brent! Thx once again.
Bob Maag

WerbyFord

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Re: 428CJ
« Reply #17 on: August 09, 2018, 07:06:11 PM »
Brent,
Glad this thread bumped, I missed it the 1st time.
Are those the same headers as on the "twin" build from just over a year ago?
I guessed 2x31 primaries, and a 3.5 x 24" collector/extension. (Sometimes exhaust details matter, sometimes they don't)
The headers Gonk to add +13 Torq and +22 HP vs the iron CJ unibody manifolds - so far anyway.

Gregwill16

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Re: 428CJ
« Reply #18 on: August 09, 2018, 08:55:12 PM »
It looks alot better than it did when it left my hands Brent. Great job!

blykins

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Re: 428CJ
« Reply #19 on: August 10, 2018, 05:49:10 AM »
Brent,
Glad this thread bumped, I missed it the 1st time.
Are those the same headers as on the "twin" build from just over a year ago?
I guessed 2x31 primaries, and a 3.5 x 24" collector/extension. (Sometimes exhaust details matter, sometimes they don't)
The headers Gonk to add +13 Torq and +22 HP vs the iron CJ unibody manifolds - so far anyway.

Werb, yes, they are the same headers.  You're pretty close on the dimensions.
Brent Lykins
Lykins Motorsports
Custom FE Street, Drag Race, Road Race, and Pulling Truck Engines
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www.lykinsmotorsports.com
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www.customfordcams.com
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Russ67Scode

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Re: 428CJ
« Reply #20 on: August 11, 2018, 09:37:47 AM »
Has anyone here ever dyno the 62 375 hp 390 to see what it really made pretty funny that with a shorter stroke and smaller bore also smaller valves that engine made the same as a 428CJ really did
Just s thought
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falcongeorge

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Re: 428CJ
« Reply #21 on: November 10, 2018, 12:36:17 PM »
I think the headers made a BIG difference.  On the 425 HP 428CJ dyno mule in my book, the engine picked up 15 peak HP from the CJ exhaust manifolds to the Hooker Super Comp headers, and 20 peak HP with the FPA tri-Y headers.  The torque gain with headers was even more pronounced, with the Hooker headers beating the 428CJ exhaust manifolds by almost 40 lb-ft peak.  The 428CJ exhaust manifolds are just not that great...
The ring package is probably worth something too, even at 5500 rpm.

WerbyFord

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Re: 428CJ
« Reply #22 on: November 11, 2018, 01:07:43 AM »
Has anyone here ever dyno the 62 375 hp 390 to see what it really made pretty funny that with a shorter stroke and smaller bore also smaller valves that engine made the same as a 428CJ really did
Just s thought

That's a dyno test I'd like to see too but never have.
Based on other dyno tests of the parts though, how the cars ran, and the Gonkulator, here is what I come up with:

455 T@ 3400 370 P@ 5200 390/375 HiPo
476 T@ 3200 380 P@ 5000 428/335 CJ

The 390 is down 38 cubes (actually 37) but has a bigger solid cam, higher compression, a better chamber, way better exhaust iron, BUT smaller valves, a worse intake, and a smaller carb.
All that stuff offsets each other so inch-for-inch the 390HP wins, but still loses out a little due to the 428CJ extra inches.
That's the best I can describe it.
Of course a PROPER shootout of all the old iron would be fun, but whenever the magazines do it a lot of revisionist history results.