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.
This archive was generated by hypermail 2b29 : Sat Jan 01 2005 - 11:48:08 EST