[DeTomaso] Questions on 4v heads

wkooiman at earthlink.net wkooiman at earthlink.net
Mon Oct 25 21:00:17 EDT 2010


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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