4800-5300 = brick wall

Ike83 · Jun 18, 2007

My car flows GREAT down low as well as all the way through the mid range rpms, but I'm trying to pinpoint why my car seems to lose horsepower just before redline.

Is this caused by my stock and unported lower intake, or are my stock heads to blame?

Keep in mind my heads ARE ported and polished, and my UPPER manifold is polished as well, not to mention I have the Competition camshaft to go along with the package, but where EXACTLY is the problem here?

I'm thinking about going with the Trickflow heads and intake, but I was just wondering if I could get by with just going to a junkyard and pulling off an Explorer intake.

Basically my question is:

Should I be more concerned with a bigger (ported lower) intake? Or should I be more concerned with getting better heads? I've always heard the ported heads are good enough, but are they what's causing my high rpm bottleneck? Or is it my stock intake? Which one is more important?

ninety15.0 · Jun 18, 2007

Your stock intake...especially the lower is the biggest culprit. The stock intake is horrible and falls off dramatically after 4500 Rpm. The heads also have the same breathing problems..and also cut out at around 4500. It really depends what kind of port work was done to the heads. Bigger valves, bowl work, and a good valve job? or just gasket matching and port massaging? An explorer intake will help...but i can attest that they too will cut out at about 5000-5400 rpm. My combo seems to run out of breathe right at 5500 rpms....so i shift just below that...approx 5300.

grey5.0beast · Jun 18, 2007

stock intake,pul it and put the explorer intakeon,mine seems to flow right up to 5500rpm with the stock heads and cam.

Ike83 · Jun 18, 2007

grey5.0beast said:
stock intake,pul it and put the explorer intakeon,mine seems to flow right up to 5500rpm with the stock heads and cam.

So the intake (lower) is probably the culprit? Good to know, b/c I don't want to get TOO much more fancy with the engine upgrades. I'm looking more into a new WC T5 transmission and hella suspension upgrades due to my stock suspension being almost non-existent at this point.

I DO know that the guy I bought the car from did a valve job, but I'm not really sure what all that entailed. And obviously he ported and polished the heads as well.

I guess I will go with the explorer intake and have one of my buddies match port the lower manifold, 'cause I'm sure that hasn't been done to the stock intake I'm currently running.

Now I know the 5.0 isn't the best highway runner, but MAN I hope this new intake will free up a few more hp in the highest rpms! That's really all I need at this point.

2000xp8 · Jun 18, 2007

I didn't see where you said what valve springs you have. Sounds like maybe a little valve float. Stock springs do not like to go above 5000rpm with a non stock cam in the car.

Ike83 · Jun 18, 2007

2000xp8 said:
I didn't see where you said what valve springs you have. Sounds like maybe a little valve float. Stock springs do not like to go above 5000rpm with a non stock cam in the car.

Ah hah! Good question. I know for a fact that the springs I'm running are completely stock. Would I have to change the rocker arms if I put different springs in, or can I keep the stock rockers?

ninety15.0 · Jun 18, 2007

you could keep the stock rockers...but they are stamped steel non-roller rockers. Get a nice set of roller rockers to add a little more lift to the cam and decrease frictional losses. Rockers combined with a nice set of springs and an explorer intake and throttle body would make a real nice improvement to your car. You would probably pick up close to 25 hp with those additions...Gas mileage would also improve noticeably. good luck.

Ike83 · Jun 18, 2007

ninety15.0 said:
you could keep the stock rockers...but they are stamped steel non-roller rockers. Get a nice set of roller rockers to add a little more lift to the cam and decrease frictional losses. Rockers combined with a nice set of springs and an explorer intake and throttle body would make a real nice improvement to your car. You would probably pick up close to 25 hp with those additions...Gas mileage would also improve noticeably. good luck.

I already have the throttle body, but what brand rockers/springs should I be looking to get? Do I have to match them up with my cam? B/c I don't know the exact cam lift/duration I'm working with being as I didn't put the camshaft in the car, I bought it as is.

So, what type of rockers/springs am I looking for here?

ninety15.0 · Jun 18, 2007

I'm running Comp Cams springs that are good to .550" lift i believe. They are dual coil springs with a damper. I'm also running the Comp Cams Pro Magnum 1.6 roller rockers. They are a real nice piece...i paid more than i wanted for rockers...actually my whole valvetrain, but i figured i would rather pay more up front and be confident in their strength and quality. The valvetrain takes a serious beating...especially if you want to run those RPM's up there frequently....so dont skimp here.

Ike83 · Jun 18, 2007

ninety15.0 said:
I'm running Comp Cams springs that are good to .550" lift i believe. They are dual coil springs with a damper. I'm also running the Comp Cams Pro Magnum 1.6 roller rockers. They are a real nice piece...i paid more than i wanted for rockers...actually my whole valvetrain, but i figured i would rather pay more up front and be confident in their strength and quality. The valvetrain takes a serious beating...especially if you want to run those RPM's up there frequently....so dont skimp here.

Would you assume that this same valvetrain combo would work for my setup? I mean, money is definitely NOT an issue. I just want the best for my 302, plain and simple.

ninety15.0 · Jun 18, 2007

Its a tough call b/c you don't know what cam you have in the car. I would give comp cams a call and talk to one of there tech guys and see what they recommend. Push rods may also be a concern depending on what was done to the heads in terms of decking and installed spring height. A length checker after you get everything assembled will be your most accurate method. Length checkers can be purchased for relatively short money and are good insurance and ensure you only go through that process once! good luck man

Ike83 · Jun 18, 2007

ninety15.0 said:
Its a tough call b/c you don't know what cam you have in the car. I would give comp cams a call and talk to one of there tech guys and see what they recommend. Push rods may also be a concern depending on what was done to the heads in terms of decking and installed spring height. A length checker after you get everything assembled will be your most accurate method. Length checkers can be purchased for relatively short money and are good insurance and ensure you only go through that process once! good luck man

Now, I'm talking to some mechanic guys up here in the office who are quite familiar with mustangs, and one of them says that if the guy I bought the vehicle from did a valve job and p&p the heads, then there's no way he would have put the heads back on with the same stock valve springs.

Ike83 · Jun 18, 2007

Plus he's also saying that the ported and polished heads flow very well if done right (meaning I don't need new heads), and it's the stock intake that blows ass when it comes to the Mustang 5.0. He's recommending the explorer intake, and says that I'll be very impressed with the gains in hp upon installation.

ninety15.0 · Jun 18, 2007

I agree that it would be strange to install the worn out springs on the newly worked heads...but trust me i have seen worse. I'm not quite sure how you could check them short of removing the springs and checking the spring pressure against the advertised spring information. Perhaps there's a part number on the springs or something so you can find some info. Again the power drop off depends on how heavily the heads were worked. You have to do a lot to get stock E7's to flow well up top. You can often get great port velocity which leads to great low end and throttle response...but getting the high RPM flow requires additional volume. good luck

Ike83 · Jun 18, 2007

I believe I will start with the intake first. Hopefully, that will fix my high rpm problem. If that doesn't work, I will take a look at the valve springs.

2000xp8 · Jun 18, 2007

Take care of the springs when the intake is off to be replaced. Kill 2 birds with one stone. Do the roller rockers too at that same time also.
Floating a valve can result in a bent valve or pushrod. Trust me, you don't want that. That means the heads have to come off.

Ike83 · Jun 18, 2007

2000xp8 said:
Take care of the springs when the intake is off to be replaced. Kill 2 birds with one stone. Do the roller rockers too at that same time also.
Floating a valve can result in a bent valve or pushrod. Trust me, you don't want that. That means the heads have to come off.

We might pull the valve covers while we're at it and take a look at the springs, but they may BE aftermarket springs already. I want to see what the new intake will do before I go any further. You have to understand that I DON'T know what the specs are ON my cam, therefore I'm really trying NOT to get involved with all that nonsense at this point. But we'll take a peep at the springs and I'll let y'all know.

Mr. Rustypwnz · Jun 18, 2007

well you better get into that nonsence right now!! Valve float isnt fun!! Get at least a explorer intake, or have t-moss port your intake, it flows right above a gt40 and it looks stock so you have the sleeper effect!!

Ike83 · Jun 18, 2007

slow95gt said:
well you better get into that nonsence right now!! Valve float isnt fun!! Get at least a explorer intake, or have t-moss port your intake, it flows right above a gt40 and it looks stock so you have the sleeper effect!!

How do we know if my problem simply isn't enough air flow due to the bottleneck in my intake?

I say let's try the intake first before we have to go searching for rocker arms and springs that match cam shaft specs I'm not even sure of.

Ike83 · Jun 18, 2007

slow95gt said:
well you better get into that nonsence right now!! Valve float isnt fun!! Get at least a explorer intake, or have t-moss port your intake, it flows right above a gt40 and it looks stock so you have the sleeper effect!!

Wait a minute.......time out! Are you suggesting that my stock intake ported will flow BETTER than a gt40/explorer intake? If that's the case then I'll have my boy port it out for me. I mean, am I wasting my time looking for an explorer intake or should I just port the stock one I have?

Now I'm confused

4800-5300 = brick wall

Ike83

Member

ninety15.0

New Member

grey5.0beast

Cookies should never be DUNKED!!!

Ike83

Member

2000xp8

Ike83

Member

ninety15.0

New Member

Ike83

Member

ninety15.0

New Member

Ike83

Member

ninety15.0

New Member

Ike83

Member

Ike83

Member

ninety15.0

New Member

Ike83

Member

2000xp8

Ike83

Member

Mr. Rustypwnz

Advanced Member

Ike83

Member

Ike83

Member

Similar threads

4800-5300 = brick wall

Member

New Member

Cookies should never be DUNKED!!!

Member

Member

New Member

Member

New Member

Member

New Member

Member

Member

New Member

Member

Member

Advanced Member

Member

Member

Similar threads

Privacy & Transparency

Privacy & Transparency