Re: 3.9L cylinder head work

From: Bernd D. Ratsch (bernd@dodgetrucks.org)
Date: Sun Apr 01 2007 - 19:28:17 EDT


You can produce plenty of power with the stock camshaft - heck, I made
288RWHP and 381RWTQ with the stock block and PCM (Supercharger and a
mild 50HP itrous intercooling). Right now, i'm making my best power at
3000-5500rpm (cam/heads/intake/exhaust combination)...but that's with a
lot of mods - 221RWHP last time we dyno'd it - still need to retune it
though for the MS109 fuel I use.

I drive mine daily as well - even with all the mods I've done over the
years. Nothing "radical" as I didn't want something just for the
weekend...and she gets 17-20mpg to boot. :)

The cam specs they list are using a max of a 1.6:1 rocker. With the
1.7:1, you'll definitely need to change the valvesprings to handle the
.540"-.560" lift. That's a lot of lift for a V6..make sure you have
them check the valve to piston clearance. BTW: It's a bit
confusing...they show it for a V6 but the description is for a V8
(5.2L). My cam is close to that but with a little more overlap due to
the 10.75:1 compression i'm running...still streetable though.

On the engine buildup, you're on the right track. Mild cleanup work on
the heads, 1.7:1 rollers, headers, intake manifold runners cleaned up
and smoothed, 180 t'stat, 50mm TB, and a decent exhaust...you'll be
more than happy with the results. If you can...bump up the compression
to 9.5:1 with some KB Silvolites ($150 for the set) and you can still
run mid-grade (Super preferred though).

- Bernd

msnbcnnbcbs@hotmail.com wrote:
> Hi Bernd,
>
> I keep getting into an argument with the friend of mine, hes telling me I
> cannot produce any power with the stock camshaft. He is telling me I need to
> rev the engine to 6k (or more) to get any decent power out of it.
>
> My issue is if the cam needs to come out, things start getting prohibitively
> expensive. between a new cam, a valvetrain that can handle 55000+ rpms, and the
> custom tune, along with all the items i described below, i may be looking at
> close to $5,000. My budget was around $3,000. He is telling my upgrades are a
> waste of time without a cam swap. Besides, this truck is a daily driver and I
> didnt want to do anything too radical.
>
> My idea was to put as much power out using the stock cam as I could. I've seen
> stock V6 heads, and they dont look to good. I happen to be near a shop here in
> south florida (mesa balancing) that has done some head work for 3.9's in the
> past. I was hoping to get a 2nd set of heads, have them worked on, get the 1.7
> rockers on, a new set of headers, the superchips tuner (3715, ive used it
> before and I got some good butt-dyno feelings from it), new injectors, and
> possibly have the intake manifold worked on.
>
> heres the link again:
>
> http://www.hughesengines.com/partDetail.asp?partID=10697&eTypeID=10
>
> if that doesnt work, the part number is HER0814AL-V6. Someone on the list
> reccomended this cam. He used it on his V6 build-up, cant remember who it was
> though....
>
>
>
>
>
>
>
>
>
> In article <46102144.1080205@dodgetrucks.org>, bernd@dodgetrucks.org ("Bernd D.
> Ratsch") writes:
>
>> I don't have any hard numbers from a before and after, but I have
>> extensive head work on my 3.9L and it made a world of difference with
>> the cam selection. For the stock cam though, there is no need for
>> polishing work unless you plan on running either a supercharger or
>> alcohol/nitro. You actually want some "tumbling" in the intake
>> portion. On the exhaust side...go ahead and polish them if you want.
>> Best place to actually polish the heads is in the combustion chamber -
>> it control detonation (removes hot spots from high/low casting flash
>> spots).
>>
>> The 1.7's will work really well with the stock cam but don't plan on
>> revving the engine past 4800rpm - the stock cam falls flat at about
>> 4600rpm...even with the 1.7's.
>>
>> The stock PCM will be able to compensate for mild cam/head changes...to
>> a point. Don't go overboard though with the cam/head porting work
>> though - you will need to put it on a dyno to get the PCM tuning done
>> right. These generic "custom flashes" are more of a headache than
>> they're worth - yes, I deal with those as well at the
>> dealership...nothing but problems until we get them on a Dyno and use
>> either an AEM or ROE controller to fix their screwups.
>>
>> I tried to look at the cam link you wrote...but it isn't coming up for me.
>>
>> - Bernd
>>
>>
>>
>> msnbcnnbcbs@hotmail.com wrote:
>>
>>> anyone have any numbers on the gains for a port/polish on the heads on a
>>>
> 3.9L,
>
>>> with a stock redline?
>>>
>>> I'm asking because Im getting my parts list together and would like to
>>>
> avoid
>
>>> yanking the cam out and having to have the computer reprogrammed. Or can
>>>
> the
>
>>> computer adjust so long as the cam profile isnt too radical? Im trying to
>>>
> avoid
>
>>> downtim as the truck is a daily driver and I need to give it some ballz so
>>>
> I
>
>>> can race it at the track without running 17's and looking stupid :)
>>>
>>> fyi, its something like this:
>>>
>>> 2nd new/rebuilt set of heads with port/polish (gonna grab em from ebay and
>>>
> have
>
>>> them taken to a shop near me that does headwork)
>>>
>>> 1.7 Rockers (the harland set from summitracing)
>>>
>>> new set of "long-tube" headers (stock ones will most like not come
>>>
> off/break)
>
>>> new 19lb/hr injectors (have them, need to install them)
>>>
>>> new doubler-roller timing chain (have, need to install)
>>>
>>> superchips tuner 3715 (used to have this, its in the mail)
>>>
>>> not touching the cam because of computer issues (unless it can adjust)
>>> specifically, this one
>>> http://www.hughesengines.com/partDetail.asp?partID=10697&eTypeID=10, as I
>>>
> cant
>
>>> afford the downtime.
>>>
>>>
>>>
>>> thanks.
>>>
>>>
>>>
>>>
>>>
>>
>
>
>
>



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