Just like it says. What is more restrictive to the whole airpump we know as the 5.0L 302 V8 engine? Please post your opinion on this and reasoning for it. Thanks in advanced for any and all responses 
Stock heads vs. intake. What is more restrictive?
- Thread starter JJ95GTID
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Zero Signal
Active Member
It's hard to tell, I don't know if anyway has run aftermarket heads with the stock intake. That should be enough to tell you which one is worth more power at least. But power per dollar the intake would probably win.
CManT1914
New Member
I was reading an MM&FF magazine, and they were saying the stock heads were quite a bit more restrictive than the intake. With an Edelbrock Performer 5.0 intake, you gain 37 HP, but with the Performer 5.0 heads, it's around 45+. I don't remember exactly how much you gain from the heads, but you gain more from them than you do the intake. But then again, as Zero said, the intake is a lot cheaper.
Lets break this down here....
The untouched runners of the stock lower intake manifold flow somewhere in the 120 CFM neighborhood.
The intake side of an untouched E7 flow 170 CFM.
This has been proved time and time again on numerous flow benches.
Joe
The untouched runners of the stock lower intake manifold flow somewhere in the 120 CFM neighborhood.
The intake side of an untouched E7 flow 170 CFM.
This has been proved time and time again on numerous flow benches.
Joe
i believe they flow a good bit more than the 120's, although i could be wrong, but tom said he ports his lowers out to flow around 190's i believe. So that would be a 70 cfm improvement roughly,and i didn't feel a 70 cfm improvement out of his lower intake. Although dollar for dollar spent it was well worth it.
jason
jason
jermy82
Founding Member
I actually had a friend with a set of GT40 heads (not sure if they were x's, p's, or what) on his stock intake manifold. After he replaced the stock with a Trick Flow he had a pretty noticeable difference. I'd do the intake first, then the heads.
All the info I have points to the lower flowing between 130-150cfm AVERAGE (front two runners flow less). The variance comes from the different castings from different suppliers - some have much better finish and less core shift than others. The lower intake is more restrictive than the head runner normally.
VIPERn94Five-0
Founding Member
mytight95 said:
Jason, your heads have to able to flow the additional air too for you to feel the full benefit. That takes ported E7s or GT40 style heads. Forgot what your runnin for heads. Also, the cam must be able to work with the intake/heads to efficiently fill the cylinders over a target rpm range.
Thanks TMOSS. I just got a set of FRPP Y303 heads off of ebay for $700. Never been fired up. Just mounted and then taken off. I think they were a display or something. I was wondering what the max lift on the GT40 valve train would be. I am hoping that they are good for at least .510". I am planning on getting the new long runner BBK intake (if it ever comes out!). I would like to run 1.7:1 roller rockers on a cam with .480" lift (when fitted with 1.6:1 rockers).
well i have that crappy e-cam and we ported the heads at home, best we could do without sending the m out to a shop for welding and larger valves, 5 angle valve job etc. bowl blending(sorta- i did it) But they matched up to the gaskets a lot better. I guess i was wrong onthe intake, i just couldn't imagine them flowing only that much air. I was in no way knocking your piece tom. I am orering edelbrock, but i have friends with stock cars pretty much that want it when i pull it.
jason
jason
I saw it. To make the runners larger throughout the runner length will take some time - quite a bit actually. If you have the time, go for it. If you use a square corretly, you can bring the bolt intrusions inner and outer wall back to a reference point on the TB flange face so you can open up the TB runner without breaking through to the bolt holes. Put the sqaure down in the TB runner and bring out the outer bolt wall to the flange face and mark it on the TB flange face. Then use the square to bring the bolt hole inner wall out to the flange face as another reference. This wioll give you the bolt hole wall thickness. Then as you port the runner bolt intrusion, keep the cuts straight up and down and use the sqaure to check the new wall thickness periodically.
man i don't know if i can put that much time into it. they are quite small. What would you guess i could get out of it. flow wise. I will probably try it. I soaked it in acid type aluminum cleaner, and it is pretty clean in there now. So i just kinda need to round out the main intake runner to the plenum to give it a straight shot to the plenum from the TB. I think i know what you are talking about to get the thickness.
WTH-- i just thought it would be fun to tinker with it., we'll see, i have a few pieces that should be here in the next day or so for my die grinder
So i will see how it goes
jason
WTH-- i just thought it would be fun to tinker with it., we'll see, i have a few pieces that should be here in the next day or so for my die grinder
So i will see how it goesjason
