How Much Power Can Ported Stock Parts Make



How Much Power Can Ported Stock Parts Make?

I was a Chevy and Mopar owner for most of my life. I got my first Ford given to me by my Aunt in the year 2000 in the form of a ratty looking 1988 GT convertible Speed Density 5.0 5 speed car with the 3:08 gear option and premium sound system. I started looking into websites of Ford enthusiasts and reading up on the cars, their capabilities and their limitations. I did some digging and found information from a guy named Pete Turek about where to start looking for power before I ever opened a valve cover. My car was a virgin with the air silencer in place but the paint was very rough – since taken care of.

Pete gave me a clue about where the restriction was in the stock HO intake – the lower section. So, I went and had a base dyno pull made to see where I was power wise after removing the air silencer, putting on the very popular Flow Master cat back (since mine would not pass inspection) and porting the lower of the HO intake. I’d been porting heads and intakes for many years, so once I inspected and measures the lower I know it had some real power bottled up in it. I came away from the dyno with 219RWHP/290RWTQ. I did not do a pre-mod dyno. The kick in the pants was nice and so I drove it this way for a few years while I took care of fixing the paint, interior, and stuff that did not work like windows and locks. The torque band was high and it was a good street driver.

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During this same period of perusing forums, asking questions and seeing what was being said, I saw that almost everyone said the stock HO intake was good for a boat anchor and that you could not make good power with one. I had a different opinion, so I started to tell people in the forums about my experience and views with porting on a stock motor. Based on dyno data of stock SD cars, I knew I got 10-15HP from porting that lower intake and that the restriction on power was now the stock E7 heads.

Well, needless to say myself and a guy names Mike Shultz, (also know as “Thumper” who ports stock E7 heads) were ridiculed for wasting our time. Seems we got the attention of some people as we started to get inquiries about how to do this or how to help others run ported stock parts. The thing is, it was harder than you know to get good documented proof of before and after results.

One of the first to send me feedback and documentation was a French Canadian named Chris Gagnon in 2003. He ran a stock HO intake with one of my ported lowers, ported E7 heads, long tubes and a T5 in front of 3:73 gears with stock TB, stock injectors and a 4° retarded stock cam. Chris went and got a dyno which is shown below:

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Power carried well up to about 5,500 rpm and the numbers peaked at 243/292. Then, Chris took the car to the track and ran it on some slicks. He had a solid mid-12 second car with ported stock “junk”.

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As time went on, more people experimented with ported stock parts to keep the budget down and still have a respectable street/strip car. Greg ran his car with stock freshened E7 heads and ran in the low 12s N/A and low 11.15 on a 200 shot.

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One customer used one of my ported HO intakes on his Thumper E7 and Steeda #19 cam car and then swapped over to a stock Cobra to pick up some power. This was interesting in that it showed how swapping from a ported HO to a stock Cobra gained no average HP and lost a couple lb-ft of average torque but gained 5 peak HP.

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Dan Drummond started out with a ported stock length HO upper intake with a choice ported M3 stock lower also ported to try and get 300RWHP from a stock intake. He did make 270HP/312TQ to the wheels and ran some low mid-12s on that combination. I then remove 2” of length from the upper intake for him to get some more power and although he did not re-dyno, his track times fell to 12.16 @ 111 mph which takes close to 300 RWHP to do.

Dan had me max out a Holley Systemax I lower (not to be confused with the Systemax II intake) recently and he is working on another short HO upper intake he is putting on a 363 that “looks stock” but runs 10s N/A and 9s on gas – we shall see and I wish him all the luck. The Holley lower flows 308cfm and the intake is in fabrication at this time.

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Mike Hudson (aka cleanLX) also wanted to run a ported stock combination. He had me port him an HO intake that included a stock length upper and a shortened version just like I had done for Dan. Mike bought CNC ported E7 Power Heads that flow tested at 230cfm. Mike also had Buddy Rawls make him a custom cam. During dyno testing, Mike used both upper intakes. The long runner HO upper peaked out a 280RWHP/330RWTQ and when the short version was added, power jumped to 292RWHP/325RWTQ. Here are all the dyno tests together. You can see the power progression while the car was tuned and changes from a 60mm TB to a 65mm TB were made and then the upper intake swap was done...

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Interesting to me was the graph I made in Excel by taking the two upper intake final results and comparing the HP across the rpm band. The short upper gave p some power below but gained over 20HP over 5,000 rpm. Here is the graph:

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Chris Napolitano did a dyno of a stock 5spd Mustang except for a cat-back addition and then pulled the motor down for rebuilding. The interesting thing about Chris’s progression was that he started with a Speed Density Motor and did a conversion to MAF to see if he could pick up some power. Here is an Excel compilation of his testing:

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On this combination of parts, the MAF made the very same average power and 2 lb-ft more average torque. The SD made more torque up higher and the MAF made more down lower. Even though the MAF pull goes to 6,100 rpm, the averages are based on the earlier 5,500 rpm pull stop points.

Five years ago, I did a head/cam/intake. I got a good deal on some freshened Factory Stock GT40P heads (no porting allowed but they had Manley 1.85/1.55 Race valves, Titanium retainers and locks and good Comp Cams springs), MAC P headers prepared for racing (welded outside the tube, inside welds ground down), some Miller Engineering 1.7 rockers, an Explorer intake and Explorer 65mm throttle body. I took my time and installed that with a new Cloyes True Roller timing chain, installed the Speed Density cam advanced 4 degrees and set out to the dyno again to check air fuel ratio. I was rewarded with 277RWHP/330RWTQ. The car is a daily driver and it’s all I’ll ever need for that purpose.

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So, my point to all this is that it only takes 240-260RWHP to run solid 12 second quarters which is a quick street combination for a daily driver. That is not hard to make with stock parts or ported stock parts or unported GT40 and GT40P heads. You can do it with stock parts that cost a fraction of the aftermarket stuff if you are challenged by a budget. Get the stock parts ported right and 280-290RWHP is there with times in the low 12 or high 11 second quarter if your suspension is efficient and you can shift.

February 2012 Update

If you have read my article here on on porting the HO intake to the max where I put 60 hours into porting both the upper and lower HO intake, I wanted to update this article on how the intake faired when tested. Here is some basic specs on the combination:

Engine by Fordstrokers

4.030” bore, 3.25” stroke

9:1 compression Forged pistons

GT40 Ford Heads ported with 1.90/1.50 valves, unkown flow but assumed to be ~230cfm

Assume 1.20”x2.00” port inlet = 2.35 sqin with a 1/4” radius

Camshaft Innovations Custom Hyd Roller Camshaft 219/232 @.050”

Fully Ported/Welded Stock Upper/Lower Intake

19# injectors, 70mm throttle body and a 94-95 MAS

No silencer in the fender and a KN filter

Stock exhaust headers/H-pipe with the cats hollowed, 3 chamber Flowmasters out the stock tailpipes

RPM limit - 6,200 rpm

3550 trans (with later plans for a Astro A-5 built T5) and stock 3:08 gears

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The stockish exhaust was choking back some power and the final best was 280RWHP and 342 RWTQ, so some changes were made to get power up.

4.030” bore, 3.25” stroke

9:1 compression Forged pistons

GT40 Ford Heads ported with 1.90/1.50 valves, unkown flow but assumed to be ~230cfm

Assume 1.20”x2.00” port inlet = 2.35 sqin with a 1/4” radius

Camshaft Innovations Custom Hyd Roller Camshaft 219/232 @.050”

Fully Ported/Welded Stock Upper/Lower Intake

24# injectors, C&L 76mm MAF with the 24lb sample tube

No silencer in fender, a KN filter, and C&L pipe from MAF to TB

Ford Racing 1 5/8 shorty headers, Off road X-pipe from gutted stock H-pipe DynoMax UltraFlow mufflers

RPM limit - 6,200 rpm

3550 trans (with later plans for a Astro A-5 built T5) and stock 3:08 gears

Power was up 46HP and the engine is making 323 HP at the tire.

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I cut my teeth on cars in the late 60s and early 70s. Back then we did not have near the performance parts choices we have today and much of any advantage you had over the guy in the next lane was due to modifications you did to the same parts as he had – be it stock or the limited aftermarket parts that were available back then. So, modifying stock parts has always been something that I was inclined to do. Sure you can credit card a very nice and proven combination of parts that will make good power, I just have not got out of my box and I like doing it the hard way. If you’re of like mind, spend some time reading the tech here and join me.

Tom Moss

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