[DeTomaso] Questions on 4v heads

Tue Oct 26 18:53:48 EDT 2010

Yes, I agree.  50hp you can feel.

I guess, my point is that for the vast majority of us, we're better off doing a good performance build on the 4V 351C - installing a proper cam, new rings, bore/hone, new timing chain, CC heads, MSD, and paying extra attention to the valve train.  Assuming it's all done correctly and everything is matched, a 351C will make more HP than most of us can use on the street.

And, if that isn't enough, the next best step is a stroker with alum heads.

I just don't buy into the idea of running a 351C, which is know for it's humongo ports, and then filling them with something to make them smaller.  If I didn't like the size of the ports, I wouldn't run a 351C.  That's my opinion, anyway.

-----Original Message-----
>From: Charles McCall <charlesmccall at gmail.com>
>Sent: Oct 26, 2010 12:31 PM
>To: wkooiman at earthlink.net, 'Rob Dumoulin' <rob at dumoulins.net>
>Cc: JDeRyke at aol.com, detomaso at realbig.com
>Subject: Re: [DeTomaso] Questions on 4v heads
>
>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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