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Uncle Grumpy 11-26-2009 03:57 PM

I need your opinion
 
Hi

I was going to get the following parts for my '91 5.8l 4x4 and wanted to know if anyone has experience with any of them or will I be wasting my money? (ps I can't afford a big block yet!) I already have the exhaust fitted.

K&N Firk2 Air Filter, BBK Underdrive pulley kit, BBK Throttle Body, Comp Cam EFI Cam, lifters and rockers, Edlebrock Intake Manifold.

alxsnmr 11-26-2009 05:53 PM

Not sure what you did so far with your truck, but Cam and Exhaust make a real difference on these trucks. Namely the Speed Density friendly Comp Cam or other name brand (not sure about the one you listed), and a Basani y-pipe exhaust to allow the truck to push the air out efficiently are the cheapest and easiest bolt-ons for extra HP/torque you are wanting to feel at the seat of your pants.

94MustangGT 11-26-2009 06:47 PM

^

+1. If I were looking to get more performance out of a speed density 351, I would: find a nice speed density cam like alxs stated along with some used iron GT-40 heads. I would keep the stock intake tract in place for the time being. Then move on to the exhaust. I would run some short tube headers into a Bassani Y, and then into a single 3" Magnaflow muffler. More power can be had with long tube headers, though.

My .02...

TexasGuy001 11-27-2009 04:54 AM

The KN FIPK or any other CAI is a waste of money. The only gains from it will be marginal and will only be at WOT when the filter is clean. Its sucks in hot underhood air and the filters are not any good either. The bottom line is that KN lets in more dirt and is just not worth messing with. Also, the cleaning drying and re oiling is a hassle.

Use the stock air box with an I6/460 lower intake tube and a good quality paper filter. This setup gets cool air from behind the grille near the headlight instead of on top of the radiator.

I had an FIPK a while back and got rid of it.

ISO 5011 Duramax Air Filter Test Report

Air Filtration Test

Technical Articles: Debunking the K&N Myth - Why OEM is Better

Air Filters, Including My Thoughts on K&N

If your truck is your daily driver, then I don't think I would go with an underdrive pulley kit. The gain here is minimal anyway. All of your accessories like the alternator and power steering and AC will not work very well.

I would do heads and cam. That will give you the most increase. At least a cam.

On a stock engine you probably won't gain much from the intake and TB. The truck intake is fairly big as it is. With other internal mods the intake would be much more useful.

A good free flowing exhaust is a good place to start. I recommend any straight through muffler and not a chambered one.

By the way stay away from TB spacers and chips etc.

What is the trucks application to you? Is it your primary vehicle or weekend toy or is it a work horse?

TexasGuy001 11-27-2009 05:07 AM

I just noticed you already have exhaust done.

Conanski will probably chime in. He will have a good cam recommendation. You definitely want a speed density friendly one.

lew52 11-27-2009 05:19 AM

I would start with long tube headers & a good exhaust system , The cam , throttle body & intake will help alot . The 5.8 intake is smaller than the 5.0 so the edelbrock will help . The underdrive pulley kit will free up extra HP to, add a set of GT 40 heads and you will see a big improvement .... Lew

jplinville 11-27-2009 06:19 AM

FIPK only shows improvement when the rest of the engine is able to breathe...Improve the exhaust first.

1966Tbird 11-27-2009 10:38 AM

if you have the money a massair kit and a good set of afr heads or trickflow heads + a cam and that edelbrock intake and a bigger throttlebody would be a huge help but that is kinda expensive lol

rla2005 11-27-2009 10:49 AM


Originally Posted by lew52 (Post 8176629)
I would start with long tube headers & a good exhaust system , The cam , throttle body & intake will help alot . The 5.8 intake is smaller than the 5.0 so the edelbrock will help . The underdrive pulley kit will free up extra HP to, add a set of GT 40 heads and you will see a big improvement .... Lew

X2 on the intake. The stock 5.8L intake was not blessed as well as the 5.0L. Even in stock form the 5.8L intake is marginal. Any increase in airflow through the engine is going to further tax the intake and make it a bigger bottleneck. With better heads/cam and exhaust the intake needs to be upgraded.

Finding a good set of used GT40/GT40P will help, just don't spend too much money. Anything over $500 for used factory heads is too much. At that point seriously consider good quality aftermarket heads. For the money spent, they are a bargain once you get in the $500+ range.

Which cam to install is a matter of your personal goals. Plenty to choose from. Consult with a cam manufacturer and give them your wants, needs and potential combination of parts.

Personally not a big fan of underdrive pulleys on a DD, but everyone has their own opinion. I also agree with ash canning the so-called K&N "cold air intake" idea too.

Starting with the exhaust was a wise choice, IMHO. Keep your end result in mind when choosing parts, this includes any thoughts for gears, converter (auto) and tire size.

Uncle Grumpy 11-27-2009 02:58 PM


Originally Posted by TexasGuy001 (Post 8176620)
The KN FIPK or any other CAI is a waste of money. The only gains from it will be marginal and will only be at WOT when the filter is clean. Its sucks in hot underhood air and the filters are not any good either. The bottom line is that KN lets in more dirt and is just not worth messing with.

What is the trucks application to you? Is it your primary vehicle or weekend toy or is it a work horse?


The links you included certainly made interesting reading indeed. It reminded me of the old advertising/marketing/government saying that goes "tell the people the same lie long enough and it will become the truth" And sell lots of products too!

The truck is not a dd but is a toy setup with a camping back. I want to enhance the engine to work easier carrying the extra load without going overboard .





Originally Posted by rla2005 (Post 8177170)
X2 on the intake. The stock 5.8L intake was not blessed as well as the 5.0L. Even in stock form the 5.8L intake is marginal. Any increase in airflow through the engine is going to further tax the intake and make it a bigger bottleneck. With better heads/cam and exhaust the intake needs to be upgraded.

Finding a good set of used GT40/GT40P will help, just don't spend too much money. Anything over $500 for used factory heads is too much. At that point seriously consider good quality aftermarket heads. For the money spent, they are a bargain once you get in the $500+ range.


Would the basic sbf heads like found at Jegs be suitable or equvilent to the GT40 head? Is the 5.0 and 5.8l the same head? Does the replacement 5.8l head need to be limited to 1.90" valves so it doesn't smash the std pistons?


Thanks to all

andym 11-27-2009 04:18 PM


Originally Posted by rla2005 (Post 8177170)
X2 on the intake. The stock 5.8L intake was not blessed as well as the 5.0L. Even in stock form the 5.8L intake is marginal. Any increase in airflow through the engine is going to further tax the intake and make it a bigger bottleneck. With better heads/cam and exhaust the intake needs to be upgraded.

Can all this be done (GT40 heads, an SD-friendly cam, exhaust, and intake) and still run a stock SD computer?

rla2005 11-27-2009 06:03 PM


Originally Posted by Uncle Grumpy (Post 8177686)
The links you included certainly made interesting reading indeed. It reminded me of the old advertising/marketing/government saying that goes "tell the people the same lie long enough and it will become the truth" And sell lots of products too!

The truck is not a dd but is a toy setup with a camping back. I want to enhance the engine to work easier carrying the extra load without going overboard .

Would the basic sbf heads like found at Jegs be suitable or equvilent to the GT40 head? Is the 5.0 and 5.8l the same head? Does the replacement 5.8l head need to be limited to 1.90" valves so it doesn't smash the std pistons?


Thanks to all

The 5.0L and 5.8L are part of the same family so their heads will interchange. As far as piston to valve clearance, it really depends on the head design and camshaft used. Various factors such as overlap, lift, canted versus inline, valve size, piston design come into play.

GT40 heads are a better design over the older E7, E6, etc. designs from Ford. If you can find a good set of GT40/P for cheap and make them workable for cheap, go for it. But if you hit the $500 dollar mark, start looking for good quality brand new aftermarket heads. Depending on your goals it may be money well spent to go for Trickflow or the now defunct Canfields if you are looking for serious power. In any case it is the combination of parts and your performance goals that should dictate what to spend and install.

For a modest outlay of cash the torque (and the spinoff of HP) the GT40s will support might work along with the correct cam/intake/exhaust for your application and goals. I just caution anyone not to spend too much money on factory heads when trying to build some power.

rla2005 11-27-2009 06:17 PM


Originally Posted by andym (Post 8177857)
Can all this be done (GT40 heads, an SD-friendly cam, exhaust, and intake) and still run a stock SD computer?

It can be done, but you will be leaving "more on the table". A factory computer is basically tuned for stock parts and emissions. When changing any components the stock computer (both SD and MAF) will re-learn to a certain degree, but what that limit might be is anyone's guess. Most of the people in the know of how the factory Ford computers work will say that margin is roughly +/-15%. Don't hold that as gospel, but that is what my research has found so far dating back to the early EEC-IV days of the mid-80's. Add in several EEC-IV vehicles for first hand experience (whatever that is worth!).

Short story: Before the advent of true computer control I had a stock shiny one owner 2wd 1978 F250 with a 460 engine and C6 transmission. I installed a true dual exhaust, no converters needed. I then took it down to a chassis dyno shop to have it tuned. The guys worked over the 4 barrel carb., distributor and vacuum advance. When they were done it got over 15 MPG on the highway. I smoked a few Camaros, Mustangs and rice rockets at stoplight racing. Not bad for a 5500+ pound truck with a 3.90 gear and 30 inch tall tires.

Great example of what a custom tune can do regardless of whether or not you have stock or modified parts.

TexasGuy001 11-28-2009 07:04 AM

I also think that a MAF conversion would be a good modification.

I have seen people running modified 302s and 351s with cam, heads, intake, an so on with the stock air box and still making over 300 horsepower.

Also, the stock airbox setup worked alright on the 1st Gen Lightnings and they had cam heads etc.

1966Tbird 11-28-2009 01:55 PM

i am even using my stock airbox....as an under the hood toolbox lol }>


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