[DeTomaso] Questions on 4v heads

Tue Oct 26 13:31:51 EDT 2010

Will, you are probably right in that you probably won't notice 10hp. 

But a serious engine is the sum of a lot of "10 hp"s, so to speak... Just
performing a single mod to gain 10 hp won't get you much, but in a complete,
comprehensive rebuild, installing 5 or 6 of those mods gets you to the 50hp
that you can feel, even if none of them by themselves is worth a whole lot. 

Charles McCall
1985 DeTomaso Pantera GT5-S #9375
"Raising Pantera Awareness Across Europe"
http://www.poca.com/index.php/gallery/?g2_itemId=2323

-----Mensaje original-----
De: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] En
nombre de wkooiman at earthlink.net
Enviado el: martes, 26 de octubre de 2010 19:10
Para: Rob Dumoulin
CC: JDeRyke at aol.com; detomaso at realbig.com
Asunto: Re: [DeTomaso] Questions on 4v heads

You can't use a fixed number like that.  The impact is a percentage, and
you'd have to be in an extreme case for those numbers.

Case in point:  I also drive a Honda Insight (don't rub it in - i'm sick of
it).  It makes about 60hp and weighs under 2,000 lbs.  You can barely feel a
difference when you turn the A/C off, and that's probably a 25hp drain.  So,
effectively, increasing HP by almost 50% is noticeable - in the Insight.

My experience has been that it takes about 50hp to feel a difference in an
average performance car.  The upgrades that are definitely worth it are, cam
change, tuneup, gears, blower, and anything that makes it more reliable.

And, once you get to about 450hp, you can't enjoy the extra power on the
street w/out getting in trouble (with the law).  Once you get to about
550hp, you can't use the power safely without slicks.

-----Original Message-----
>From: Rob Dumoulin <rob at dumoulins.net>
>Sent: Oct 26, 2010 5:49 AM
>To: wkooiman at earthlink.net
>Cc: JDeRyke at aol.com, detomaso at realbig.com
>Subject: Re: [DeTomaso] Questions on 4v heads
>
>My intake stuffers are one piece, so no risk of becoming loose.  I have not
>installed them yet, but think I remember reading that they act as gaskets.
> The exhaust are mounted with a regular exhaust gasket on each side of the
>plate.  Last weekend, I had to add three new exhaust manifold bolts to
>replace the ones that went AWOL.  I'll admit it was probably my fault for
>not going back and re-tightening them a few weeks after I initially
>installed the headers.
>
>I've heard people say that 10HP is like removing 100 lbs of dead weight.
If
>you could remove 200 lbs from your car, would you do it?
>
>Rob
>
>On Mon, Oct 25, 2010 at 9:00 PM, <wkooiman at earthlink.net> wrote:
>
>> You guys didn't mention the negatives.
>>
>> The intake port stuffers can come lose and cause damage or at a minimum,
>> block flow and cause you to have to take it apart to fix.  Is it likely?
>>  Probably not, but it's something to worry about.
>>
>> What about leaks?  I don't know how well these things fit.  Can they
cause
>> intake manifold or header leaks?  I don't know.  Maybe.
>>
>> What about hurting performance?  It's possible that these devices will
hurt
>> performance.
>>
>> I honestly don't know if these are valid concerns.  If it were me,
though,
>> I'd focus on the easy/proven horsepower techniques.  You will never feel
>> 10-20hp with your butt-o-meter.  You WILL feel pain if a 20hp gadget
fails.
>>
>>
>> -----Original Message-----
>> >From: cengles at cox.net
>> >Sent: Oct 25, 2010 1:07 PM
>> >To: JDeRyke at aol.com
>> >Cc: detomaso at realbig.com
>> >Subject: Re: [DeTomaso] Questions on 4v heads
>> >
>> >
>> >Dear Jack,
>> >
>> >About twenty years ago I used MPG intake and exhaust port plates. While
I
>> thought that they made more power, that was mostly a hope and a guess and
it
>> was never measured. In my review of exhaust port plates, they are usually
>> described as improving exhaust flow and they usually *imply* improved
power,
>> but I could never find any dyno evidence of actual benefit.
>> >
>> >Recently Dan Jones' Great 351C Dyno project actually tested the MPG
>> Stinger Port "plates". They are bronze and have a solid tongue or stinger
of
>> brass that sits low on the floor of the exhaust port. Dan's dyno testing
>> showed (I am going on memory here and I have slept since he posted it)
only
>> about 5 horsepower improvement. It was way less than 20 hp.
>> >
>> >I think that properly used with a complimentary intake manifold and cam,
>> intake port stuffers can give an honest 20-30 hp. I think that the HP
>> benefits with the exhaust port stuffers is much more modest. [....but
five
>> hp *is* hp....]. Cost per the MPG website is $90 for a set of
intake&exhaust
>> stainless steel port plates and $175 for a set of Exhaust Stinger Port
>> Plates. Again, as I glanced at the website they allege 20 hp and 20
ft-lbs
>> improvement with their steel set, but not dyno sheets are shown nor
>> provided...........
>> >
>> >Warmest regards, Chuck Engles
>> >
>> >
>> >---- JDeRyke at aol.com wrote:
>> >> In a message dated 10/25/10 7:19:04 AM, dave at damardirect.com writes:
>> >>
>> >> > Hi Jack,
>> >> > What is your opinion on exhaust port plates? W/o intake port
stuffers?
>> >> >
>> >> Never actually used either; I got lucky in 1990 and found a lightly
used
>> >> pair of SVO aluminum heads that already had closed chambers,
adjustable
>> >> valvetrain and raised ports. Generalizations are worth what you pay
for
>> them ($0
>> >> here), but my understanding on 351-Cs is,
>> >> 1)- intake port stuffers can make maybe 20-30 bhp extra (~10%) on a
real
>> >> 350+bhp engine, at some rpm levels, depending on the intake & carb
>> they're
>> >> paired with.
>> >> 2)- Exhaust plates do less than intakes but can pick up maybe 10-20
more
>> >> bhp (~3-5%) on a real 350+ horse engine, again over certain rpm
levels.
>> Lots
>> >> of caveats- including starting with closed-chamber iron heads,
>> semi-equal
>> >> length headers and more open exhausts than stock Ansas. There are 2
>> designs I'm
>> >> aware of: cast-stainless or cast-bronze to take the heat, and are
>> bolt-ons
>> >> between the heads and header flanges, not welded, pinned or glued.
>> >> Port plates are Band-Aids for head design problems. Both intake or
>> exhaust
>> >> plates need replacement or at least tuning of other engine parts for
>> most
>> >> drivers to even notice them except that they may change the exhaust
>> note. A
>> >> couple of vendors sell these; I'd call around and ask them what effect
>> they've
>> >> seen on something like your engine- and have a parts list handy 'cause
>> they
>> >> will ask whats in there. FWIW- J DeRyke
>> >> _______________________________________________
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>
>
>-- 
>Rob DuMoulin
>904.476.8744
>rob at dumoulins.net
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