RE: RE: 318 vs 390 power

From: Chad Evans (hemidak@msn.com)
Date: Thu Dec 16 2004 - 13:24:18 EST


He builds custom dakota r/t's if you must know. Custom as in one-off parts.
Not some parts from a catalog. Builds 99%(close to it anyway) of the parts
in house.

His R/T that ran 12.7's was on slicks and using slide-a links. That was a
mild 408 that is driven on the street.

>From: "greg conner" <dodgeboy93@hotmail.com>
>Reply-To: dakota-truck@dakota-truck.net
>To: dakota-truck@dakota-truck.net
>Subject: RE: DML: RE: 318 vs 390 power
>Date: Thu, 16 Dec 2004 09:38:24 -0500
>
>
>rut roh... super secret dakota project man...
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>>From: "Chad Evans" <hemidak@msn.com>
>>Reply-To: dakota-truck@dakota-truck.net
>>To: dakota-truck@dakota-truck.net
>>Subject: RE: DML: RE: 318 vs 390 power
>>Date: Thu, 16 Dec 2004 01:33:32 -0600
>>
>>
>>My boss's r/t 408 runs 12.7's N/A
>>
>>>From: "RayB" <bpracing@worldnet.att.net>
>>>Reply-To: dakota-truck@dakota-truck.net
>>>To: <dakota-truck@dakota-truck.net>
>>>Subject: DML: RE: 318 vs 390 power
>>>Date: Thu, 16 Dec 2004 02:22:54 -0500
>>>
>>>
>>>All things being equal, more cubes + longer stroke = more power...but
>>>most
>>>importantly for a daily driver, more torque. If you're not going to race
>>>this thing then build whichever engine for torque instead of high rpm
>>>power.
>>>Consider your driving habits and if you seldom have the room to wind it
>>>out
>>>through the gears, you will be much happier with lower rpm torque.
>>>
>>>You didn't mention what gear ratio you have but something in the 3.90 -
>>>4.30
>>>range will also get you moving a lot quicker. A 2400 stall converter
>>>would
>>>also be nice.
>>>
>>>I can give you a couple pieces of advice from personal experience. That
>>>RT
>>>cam you have is no great improvement even in a 318 (too mild). The RT
>>>heads are gonna hurt a 318 and are unnecessary even on a 390 if your goal
>>>is
>>>low to mid range torque. You can do much better with a mildly ported
>>>stock
>>>head with 1.97 intake valves for a lot less money. The RT heads simply
>>>have
>>>ports too large for a relatively low rpm street engine. I've
>>>encountered
>>>several 360 and 408 Daks that can't come close to the performance of my
>>>318.
>>>Check it out at the dragtruk link in my sig. It's all in the
>>>combination
>>>and bigger done wrong isn't always better.
>>>
>>>Whichever engine you ultimately decide to build, it would be wise to
>>>discuss
>>>your combination and goals with a cam manufacturer (not just a vendor)
>>>before choosing the cam and rocker ratio. As for superchargers...I have
>>>a
>>>friend with a Vortec blown 318 that runs mid-12's @ 110 and it's also
>>>awesome on the street. HTH.
>>>
>>>RayB
>>>http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
>>>
>>>
>>> > -----Original Message-----
>>> > From: kvmac45@comcast.net
>>> >
>>> > Question on power. I am in the process of accumulating parts for
>>> > an eventual
>>> > engine rebuild/swap for my 92. Have the current mods that will be
>>> > on the new
>>> > engine.
>>> >
>>> > M1
>>> > MSD6AL
>>> > Blaster SS coil
>>> > K&N filter
>>> > March underdrive pulleys
>>> > Thorley headers
>>> > Ported/polished TB - 50mm
>>> > Electric fan conversion
>>> > Mopar PCM
>>> >
>>> > I also have the Mopar RT cam 5249549
>>> > 260/264dur/.458/.467lift. It is not currently in the truck. I figure
>>>it is
>>> > probably too small for a 390, but will work great in a 318 with my
>>>current
>>> > mods. Reason I got it was the price - dirt cheap. I bought it
>>> > before the 390
>>> > bug hit. Also have a set of 1.7 Crower rockers that are waiting
>>> > until I get the
>>> > heads.
>>> >
>>> > I will be getting a set of RT heads regardless of what engine I
>>>ultimately
>>> > decide to put in. I figure 1.92 for the 318, or 2.02 for the 390.
>>> >
>>> > Just how much of a power difference will I see in a 390 vs. a
>>> > strong running
>>> > 318 with the above mods, including the cam and heads? Trying to
>>> > decide if it is
>>> > really going to be worth the extra expense to get the parts for a
>>> > stroker. This
>>> > is my daily driver, so downtime is limited to weekends only. As a
>>> > result I will
>>> > be building up the engine on the side, then performing the swap
>>> > when it is all
>>> > ready to go. This is not a drag project or anything like that. I have
>>>190k
>>> > miles on the engine, with no opportunity to get another vehicle
>>> > anytime soon,
>>> > except for a beater car, which I do not want to do.
>>> >
>>> > I know for the 390 I will need to get the block bored and clearanced,
>>>new
>>> > pistons and rings, connecting rods and a 4" crank. For my truck I
>>> > figure a 360
>>> > PCM and 21-24# injectors would be a good idea too. Probably bump
>>> > up to a 52mm
>>> > TB, and eventually one of the high flow Holley fuel pumps.
>>> >
>>> > Ultimately it may come down to money, but I want to give it a
>>> > shot if the gains
>>> > are going to be worth it. Of course, I could always go with the
>>> > 318 and then
>>> > throw a s/c on it later next year too.
>>> >
>>> > TIA, sorry for the long winded post.
>>>
>>
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