was wondering if someone could give me a idea of how much HP the following mods would make on my 85 351w HO.

block bored .030 over
Federal Mogul rebuild kit using Speed Pro hypereutectic pistons
(9.17:1 compression with 63cc heads)

Edelbrock performer intake manifold

Edelbrock performer cam kit
270 intake / 280 exhaust, at .050 204 intake / 214 exhaust
lift .448 intake / .472 exhaust
lobe sep 112 degrees

Holley commander 950 TBI 700 cfm

World products windsor aluminum heads
64cc chamber, 200cc intake runner
valve diam 2.020 intake / 1.60 exhaust
.600 max lift

kind of not decided on the heads though was also looking at the world 180 Jr.
and even the ford gt40p heads. What would a smaller head like the 180 Jr do?

world products 180 Jr cast Iron heads
58cc chamber, 180cc intake
valve diam 1.94 intake / 1.60 exhaust
.560 max lift

also was going to run all this with Dynomax headers which have 1.5 in primay and 2.5 in collector tubes. Thanks for any imput as I really want to plan this engine out before building as to waste as little dollers as possible.

 

I would say 275-300 hp max.

 

yea, I was kinda thinking 300. Would the GT40p heads flow as good as the World 180 Jr's ? I am trying to get better gas mileage as well as a little more power would like to at least hang with the new general moron's 5.3L seeing as how I got 30 more cu inches.

 

If I remember right the gt-40p flow as well as the world sr heads on the intake side, the p's with 1.84 valves and the sr's with 2.02, so that aspect is good. On the exhaust the world flow a little better, but nothing a grinder and time couldn't help out. There is a company that still sells the gt-40p heads, called tri-state cylinder heads, they offer brand new castings with larger valves (1.94/1.60) 5 angle valve job and springs assembled for $520-540.


You might consider going with a comp cam extreme energy camshaft. I have been looking at a similar combo, speaking with different custom cam makers getting ideas. I asked about a few different cams/companies including the performer cam, the choice was the extreme energy line. I have determined by their info that the XE250 35-230-3 would be a good camshaft for a combo like yours running less than 3.55:1 gears, if 3.55:1 and numberically higher then the XE256 35-234-3 would be a very good choice. This was given that engine would be used primarily on the street in a truck with a 3 speed running mainly between idle and 3000 rpms. I have also been told that from real world experience the XE262 35-238-3 performed very well in this type of application and provides great low end torque and a slightly noticalbe performance exhaust sound.

I dunno I think GM has a good thing with the 5.3, I wonder why ford never built a production aluminum block, except for the piston slap on start up, its a potent little motor.

Something to think about, later

 

Say I run the gt40p's with something like the performer RPM cam and intake with a 1000 rpm higher converter (C6) would I still be able to to use 87 octane? I have 3.70 gears now and I am thinking of going to 4.10's with a auburn limited slip differential.

I have driven several of the 5.3l equipped 1500's at work and my neighbor has one as well, I will admit it is a farily potent engine 295 hp @5300 rpm. I also however already see one problem with it, spark plug wise, anything less then Delco platinums or bosch 4 way splitfire platinum plugs and it runs like crap.

 

It all depends on your final compression ratio, you have to take into account your measurements which may be unique to your engine, gasket thickness, piston to deck height, pistons etc., so its hard to say. Figure a compression ratio of around 9.5:1-10:1 as an extreme (it all depends on the previously mentioned though), ask people local to you what kinda compresion ratio they are running and what gas they are getting away with using octane wise, as octane varies from area to area.

I am gonna sound like a broken record but the comp xe cams are better than the edelbrock no matter what you pick, there was a fella running the performer in a truck and he said it made no low end difference, but did pick up after 3500rpm, given the performer rpm is for an even higher rpm range, it would probably be a bad choice. This is just being picky becasue if you never drove it with the xe cam then you'll never know or care. I'm just saying I have beat that issue to deal talking to three people who do nothing but set up custom cams and they didn't like the performer at all for a truck application. They leaned towards something a little closer to stock like a rv cam/ torque cam, and the XE fit the bill. Who knows? Good luck though with what ever you decide, keep us updated on your progress

 

hum, I used the RPM mainly as an example of a higher rpm cam. What would the comp cams equilevent be? Also just for kicks any idea how the old D00E castings compare flow wise to the gt40p's? Is there a better manifold then the edelbrock around the same price (I will have to have a square bore for the TBI.)? I figure it would be cool to have a 351 with 351hp however gas is a concern also.

 

I get what you saying/wanting.

One thing I have noticed is when people get a custom cam, they almost always say, it was smaller than I would have picked/ expected. Sometimes the smaller grind is all that is required.

I bet your looking for something of a performance (rumpity) note from your exhaust. The XE262 will give something of a note, the XE268 will as well, I have heard the 268 in a 351w with gt-40p heads, it sounded real good. The owner used a stock converter but made the comment it really needed a bigger converter, wanted to lunge a bit when stopped. The XE262 (35-238-3) holds low end torque pretty good compared to the smaller XE250 or XE256, the XE268 (35-242-3) begins to drop slightly, but picks up after 3500-4000rpm greatly hp wise compared to the others, but you'd expect that as you move up to a bigger cam. Call comp they will get you what you want...... 1-800-999-0853

I would say go with the weiand stealth intake, ideal range is idle to 7000, and I believe that to be correct.

The gt-40p flow something like 194 intake and 140 exhaust cfm at .5" lift, the 351w DOOE flow something like 190/120 cfm, they have similar combustion chambers at 58cc, a little port work would let the DO exhaust flow similarly to the gt-40p. The gt-40p do have smaller valves stock than the D0OE heads which mean they are a little more efficient, theoretically. There is also the spark plug / header clearance issue with the gt-40p's.

Use this site to compare flow data:

http://www.jason.fletcher.net/tech/f...a/castiron.htm

Later

 

Yep, pur like a kitten and roar like a lion. Was looking at PAW and was wondering what thier equilevent to the comp cams you mentioned would be or if they would perform similer?

 

I was inaccurate in the above post, the gt-40p and D0OE heads have the sam intake valves the exhaust however is smaller on the gt-40p, yet they still flow better.


Well I will be honest, I spoke with two different custom cam makers and specifically mentioned a similar combo as yours in a truck application, and gave them the specs of the first three paw cams, they didn't care for any of them. They are old crane designs, one is actually the same as the performer cam you listed. So when you think about it paying $99 for a new design is worth it vs paying $49 for something older. The main thing is the comp XE will give you more cfm potential at different lifts which is good, and it will also give you better manifold vacuum.

As a thought, the gt-40ps flow similarly on the intake as the world sr with 2.02 valves vs the gt-40p with 1.84, the exhaust is better with the world but nothing that cannot be pulled out of the gt-40p with some port work, the smaller valves of the gt-40p and equal cfm flow compared to the world mean the gt-40p are a bit more efficient design wise and the smaller valve should theoretically make the throttle response a lot better, and they are cheaper. The gt-40p were based design wise off the D0OE heads from what I have heard. Didn't mean to ramble, but this is my favorite topic, later

 

GT40p's based on D0OE, hum that would be interesting. I am strongly considering a set of 69 D0OE heads. I can get a pair for $139 complete although used. I figure new springs, a good cleaning of the valves or new ones, and some grinding of the intake and exhaust sides. I could use the savings for a set of aluninum roller rockers and it should work for me, I hope anyway.

 

Sounds like a fair price...I just picked up a set (DOOE) heads myself. Don't forget you need to install hardened exhaust seats. Better yet give me $280 plus shipping and they are yours. haha. my plans have changed, three angle valve job, crane springs and come with adustable locking nuts and stock rockers, the exhaust has been ported on these, intake was gasket matched to a 1262 felpro gasket, also has hardened exhaust seats. Came off a mustang that ran a 302 naturally aspirated, using these 351w heads it ran a high 11. Not bad huh? Later

 

I'll think about that Is this the cam you were referring to earlier?

Specifications:
* Duration: 262 intake/270 exhaust
* Duration at .050 in.: 218 intake/224 exhaust
* Gross valve lift: .493 in. intake/.500 in. exhaust
* Lobe separation: 110 degrees
* RPM range: 1,300 to 5,600
* Excellent response, good mid-range, stock converter, 3.23 to 4.10 gear

Or maybe this one?

Specifications:
* Duration: 268 intake/280 exhaust
* Duration at .050 in.: 224 intake/230 exhaust
* Gross valve lift: .510 in. intake/.512 in. exhaust
* Lobe separation: 110 degrees
* RPM range: 1,600 to 5,800
* Great for Street Machine, 2,200 plus stall

 

That would be it.......just remember the 250 or 256 would give better low end torque.


If you would want to see pix of the heads, I have them. later