Stupid question about the biggest 5.0 restriction

FastDriver · Feb 8, 2019

I contend that the intake is the biggest restriction on a 5.0 HO. Another guy made the point that if you bolt a stock intake to a set of AFR165s, you'd make more than the 240rwhp commonly seen with bolt-ons and an aftermarket intake. I'd actually like to see this. What is the most power you've ever seen on a stock untouched, unported 5.0 HO intake. Extra points for the stock TB & MAF.

His claim actually sounds feasible to me, but not once in my decades of foxbody stuff can I remember ever seeing anything like that. So, I'd like to know. It's just a point of curiosity.

Dan02gt · Feb 8, 2019

If I remember correctly there was a guy on here a year or so ago with 1.90"/1.60" Edelbrock heads and pretty much everything else stock. If I remember correctly his car made in the 230s. He swapped to a Cobra intake and that put him into the upper 280s.

FastDriver · Feb 8, 2019

Awesome! Link?

JD1964 · Feb 8, 2019

Consider that velocity is an important factor. When better heads are put on, the pistons can pump in more air. That given amount of air passes through the throttle body and intake. With a smaller TB and intake runner such a stock, that doesn't mean the air would be restricted. The increased volume of air would however , move through those parts at a higher velocity. The same volume of air moving at a higher velocity can actually increase performance.

Just the same, a TB and intake runner that is too big compared to the pistons ability to pull air through the cylinder head can result in low velocity of the incoming air. Low velocity incoming air may not atomize the fuel spray at the injector nozzle as good as higher velocity incoming air would.

A slightly undersized intake or TB is not necessarily a bad thing. Restricted cylinder heads on the other hand, it's tough to build on that.

JD1964 · Feb 8, 2019

Dan02gt said:
If I remember correctly there was a guy on here a year or so ago with 1.90"/1.60" Edelbrock heads and pretty much everything else stock. If I remember correctly his car made in the 230s. He swapped to a Cobra intake and that put him into the upper 280s.

I seriously wonder if the Cobra intake "alone", (nothing else was changed) netted another 50hp in this instance. Maybe so....

90sickfox · Feb 8, 2019

The biggest restriction on a stock 5.0 is the exhaust side of the head....from the valve and into the header. This has been proven time and time again. Open up the exhaust side and you find more powah.

95BlueStallion · Feb 8, 2019

There was a guy on here years ago named Grady in the then ‘94-‘95 section. He had AFR 165’s, Edelbrock upper and lower intakes, a custom cam and stock TB. Made 293 rwhp. I know that doesn’t answer your stock intake/cam question, but I always found it interesting that the stock TB wasn’t much of a restriction on his combo. He would always tell guys to save the $200+ a TB cost and put it elsewhere.

FastDriver · Feb 8, 2019

90sickfox said:
The biggest restriction on a stock 5.0 is the exhaust side of the head....from the valve and into the header. This has been proven time and time again. Open up the exhaust side and you find more powah.

Ok, that's pretty on par with his claim. I'd just like to see the evidence, because I've been in the game a while and to this point, I haven't. So, if you have a link handy, please send it my way. I'd like to know. Swapping intakes is an easy 15 rwhp on an otherwise stock motor. What is opening up the exhaust port worth?

General karthief · Feb 8, 2019

Seems like the exhaust restriction would be the reason for the old trick to use 1.7 rockers on the exhaust side?

90sickfox · Feb 8, 2019

FastDriver said:
Ok, that's pretty on par with his claim. I'd just like to see the evidence, because I've been in the game a while and to this point, I haven't. So, if you have a link handy, please send it my way. I'd like to know. Swapping intakes is an easy 15 rwhp on an otherwise stock motor. What is opening up the exhaust port worth?

Challenge accepted. When was the last time you looked at an e7 exhaust port ?...

I searched and searched online....just found a bunch of people that said it in other forums. This is something I've personally seen proven at the track. These tricks come from the old school guys that new how to squeeze power out of these engines. You'd have to find it in an older horsepower or engine building magazine.

Because of emissions Ford choked the exhaust side of the heads....you can look at them and tell. Maybe they did that so the internal egr valve would have enough flow.

Think about it like common sense...

You have air and fuel coming into the chamber through larger openings and larger valves. Combustions happens and heat expands that mixture enough to force the piston down. That blown up mass of gas then has to exit through a smaller valve and out through a smaller hole....with a ridge and a bump in its path.

Why do you think aftermarket camshafts increase lift and duration on the exhaust side ? That's what set these " new " camshafts on a bar above alphabet cams. Ya know how they figured that out ?....it was the uses putting 1.7 rockers on the exhaust side increasing lift. Ya know why it worked ?....because the exhaust valve had to open more to even the flow out of the head.

I had fast ported e7 heads....the exhaust ports were matched to my bbk headers and had 1.6 valves. Those heads ran circles around a bunch of guys. I don't have dyno sheets or time slips to prove it....so I'll leave that alone....but I didn't have an ugly 10 point cage in my convertible for nothing.

Wish I could've found some verifiable info on the web. These cars have been modified since way before the internet.

Its like using an escort alternator pulley to spin a 130a alternator faster to get away from the lights flashing at idle with a sound system. It's like using truck lower intakes and sheet metal uppers grafted to a chopped up truck intake ( how trickflow started ). There are a bunch of small things that have been proven to make power.

I'm not saying the intake isn't restrictive....just the bottle neck is at the exhaust side if the head. With a good camshaft it can help by opening that exhaust valve more....at that point the intake will start to show its weaknesses. We all know that power is a combination of things.

I guarantee that if I had an all stock fox...with only the exhaust side of the head ported, with a bigger valve, I'd pull away from an all stock car. If you put a decent intake on an all stock car- an all stock car will run right with it.

I rest my case....

FastDriver · Feb 9, 2019

Haha! Thanks for the attempt, brother. I did too.

It's a dumb argument, anyways. I'm just curious. What "the biggest restriction" is doesn't really matter. Also, there's not a thought in my mind that the E7s, and their exhaust ports, aren't extremely limiting. There's a reason you can pick up 90rwhp or more with a good head.

That's all. It would be interesting to see what's been pulled out of a truly stock intake. I think a guy would have to be kinda dumb or just in love with the stock look to go through the trouble of doing heads and leaving the intake stock. So, having one that's been dynoed would be a pretty rare find unless that was the goal of the test on the outset, like if a company wanted to test gains of their intake on a built motor vs. a stock intake.

90sickfox · Feb 9, 2019

I agree...it doesn't really matter. The intake and e7 heads are junk. These cars wake up with a HCI swap. I ditched my stock stuff a very long time ago.

I would be very interested in seeing dyno info. The stock throttle body is very small....so... maybe that would be the biggest restriction.

We know all the factory stuff chokes our 302s... good discussion brother. Got my head churnin' and my blood flowin' .

FastDriver · Feb 9, 2019

I took a look in the combo/dyno sticky. Found one with a stock TB making like 256 rwhp or something. Did not see any big numbers from a stock intake, and didn't see any combos with modded head and a stock intake either. But the TB number suggests that its not limiting on the stock components.

5.0specialist · Feb 9, 2019

From what I've read, the stock #1 and #5 runners of the HO lower intake is the most restrictive part of a stock E7 headed engine. Those two front runners have a lot of turns and flow around 151 to 155 cfm, while the stock E7 intake ports flow an average of 160 cfm at around the stock HO cam lift rating. The third most restrictive runner flows at 177 cfm, which is more than enough. My dad (the one with the steady hands) ported my stock lower intake to match the intake head ports more closely and the two front restrictive runners were the most heavily ported. I feel like this setup with the stock throttle body and sn95 5.0 70mm maf sensor provides better overall acceleration than an explorer intake with a 65mm throttle body and a Pro-M 75mm maf on stock E7 heads (my old 93'gt setup). Both cars have the same exhaust setup and my 91' has the clutch fan, while my 93' had a taurus e-fan. I used this article as a guide: http://diyporting.com/intake_manifold.html

Dan02gt · Feb 9, 2019

FastDriver said:
Awesome! Link?

Yep I managed to dig it up.

https://www.stangnet.com/mustang-fo...ake-finally-found-and-installed.902899/page-2

aztecgwynn · Feb 9, 2019

Dan02gt said:
If I remember correctly there was a guy on here a year or so ago with 1.90"/1.60" Edelbrock heads and pretty much everything else stock. If I remember correctly his car made in the 230s. He swapped to a Cobra intake and that put him into the upper 280s.

Hey that was my car almost year ago.

FastDriver · Feb 9, 2019

@aztecgwynn, Was the only difference the Cobra intake? And did you ever take it to a track?

aztecgwynn · Feb 9, 2019

No I did not take to tracks! My 93 is daily driver so I’m easy on it!
Yes as soon as car was tuned with Cobra intake it was huge difference. I could tell on street that now engine was breathing. Also I installed a Pro M meter as well for 19LB injectors. Unfortunately the electronics in brand new Pro M were junk so tuner used stock Ford electronics on Pro M

FastDriver · Feb 9, 2019

Well, then, that would be fairly good evidence that the stock intake is done before the stock heads. I've seen quite a few untouched stock headed combos running in the 240s.

aztecgwynn · Feb 9, 2019

I know when I had stock upper lower intake with edelbrock heads I had more torque less horsepower. But once cobra intake was installed with edelbrock heads I gained horsepower but lost torque

Stupid question about the biggest 5.0 restriction

I was uncomfortably high & wearing a helmet

mazing how much gas smell came from that tiny hole

I was uncomfortably high & wearing a helmet

there is enough sticking out to grab on to

there is enough sticking out to grab on to

Wasn't a pretty sight...and I've got big hands

My assy trans to myself

I was uncomfortably high & wearing a helmet

wonder how much it would cost to ship you a pair

Wasn't a pretty sight...and I've got big hands

I was uncomfortably high & wearing a helmet

Wasn't a pretty sight...and I've got big hands

I was uncomfortably high & wearing a helmet

Active Member

mazing how much gas smell came from that tiny hole

Active Member

I was uncomfortably high & wearing a helmet

Active Member

I was uncomfortably high & wearing a helmet

Active Member

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