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Want to build a boss 302 or 331....

August 7 2012 at 11:37 AM
Jim  (Login 69fstback)
Member
from IP address 68.39.85.172

I have a 79 mustang and I really want to build a 8.2 deck boss 302 or 331....

I know I can do the 302 with stock crank, 289 length rods, and a boss piston. Or 5.4 rod and 1.3 piston
331 would be 3.25 crank, 5.325 rods, and a 1.250 compression Cleveland piston.

I want this for mainly a street car... Car has 4.30 gears already...Built Aod so overdrive is nice with the 4.30s
Looking to have the same caratistics as a old boss 302...high revving etc
Hoping to get 3200lbs down the 1/4 in low 12s high 11s
Be able to jump in and head down the road... Two pumps of the carb and I'm off...
Pump gas/reliable 93

Things I have already... Which lead me to this build...

Clevor modded 351 4v cc heads
Mexican 302 block bored 30 over fresh
Stock crank
Buddy of mine has a boss 302 intake I can borrow until I find a track boss or another intake
2 sets of forged Cleveland pistons (gotta measure compression height)


Basically I need help making a good combo with the smaller cubes... Should I go high revving 302? 7500rpm...since torque shouldn't be to bad with 4.30 gears...

I think I read go small duration/high lift to get a boss 302 to run? Like 225/230@50 with like 580/595 lift on a 111 intake center line? Trying to get 12-14 vacuum at idle...


Thanks! How did you guys get your old bosses up and moving?!?

Some help would be appreciated....

 
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Brent Lykins, B2 Motorsports
(Login blykins)
72.4.3.130

They're turds.....

August 7 2012, 12:05 PM 

Anytime you put 302 cubes with a 235-240cc head, you're going to have to spin the pee out of it to get anywhere. Yes, the 4.30 gear will help and yes the light weight will help, but keep in mind that a 7500 rpm engine is not a street engine and will absolutely be a dog on the bottom end.

If you do plan to turn that many rpms, you will need duration and a ton of it. No vacuum.

I do Boss 302's for vintage Mustang stuff and the engines have no butt to them.

I would throw as much stroke as you can to it, skip the 331 and go with a 347, and stay away from the 7500 rpm goals. Lower duration and ADVANCED cam timing, not 111-112 ICL's. If you can, I would put port tongues in the heads and cut the CSA way down.

Brent Lykins
B2 Motorsports, LLC








    
This message has been edited by blykins from IP address 72.4.3.130 on Aug 7, 2012 12:06 PM


 
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George Pence
(Login gpence)
A1
108.218.153.39

I kinda like Boss 302s

August 7 2012, 12:41 PM 

I've driven the factory cars and they ran just fine, even with the stock 3.50:1 gearing. I think stuffing one in your '79 is a great idea; 4.30s are the right gear for a 26" tire, according to Ford.

You don't have to ask "should I build a high rpm motor"? Because the moment you decide to bolt the 4V heads on the 302 you've already set that in motion. Its unavoidable, it shall be a high rpm motor. happy.gif So don't fight it, and don't try to make it somethng it isn't.

Basically the Boss 302 does everything 800 rpm higher than a 351C 4V. But the same Cleveland principles apply. Everything is 180 degrees backwards from motors with small ports and small valves. The Cleveland heads build the high rpm power, and the cam and intake manifold build the low rpm power. So spec a cam with relatively short intake duration and limited overlap, and use a dual plane intake manifold with a full height (un-cut) plenum divider. Carb & ignition calibration are also critical to running smoothly on the bottom end. Your 4V heads have either 63cc chambers or 66cc chambers, whereas the Boss 302 heads had 58cc chambers, so you'll have to make up that difference in volume somehow.

I think you'll like the motor, my advice is go for it.



-G
____________________________________________________________

Pantera Photos | 351C Historic Information | 351C Technical Information

[linked image]


 
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Jim
(Login 69fstback)
Member
198.228.200.157

What's a boss 302 cam look like?

August 7 2012, 12:50 PM 

I think I'm gonna go with the stock stroke... 3.0
A 5.4 rod super light 4340 I-beam... And a 1.30 Cleveland piston...light bobweight

CC 4v heads with stud girdle and roller rockers since I have them.

Intake i have the access to a stock boss 302 one for now... Probally scope eBay for a cool one.

Shooting for 10.1 compression I guess to keep it safe...

Really all I gotta do is throw the right cam at it?
What was the hopped up boss 302 catalog came way back?
I know the cam will make or break this idea... Anyway to pull 12 vacuum from it?


 
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Brent Lykins, B2 Motorsports
(Login blykins)
72.4.3.130

Like a pencil with bumps on it.....

August 7 2012, 2:29 PM 

happy.gif

Sorry, I had to.

You'll need to figure out where you want to be with the power. A factory Boss 302 cam won't get you to 7500 and you wouldn't have vacuum if you made peak hp that high.

If you want a peak hp that's lower, there are a lot better cams out there than the factory stuff. Pick the duration for the rpm you want to be at, then pick the LSA/ICL to fit the rest of it.



Brent Lykins
B2 Motorsports, LLC







 
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Jim
(Login 69fstback)
Member
198.228.200.150

Ha nice! What specs would u grind?

August 7 2012, 2:45 PM 

Based on what I'm lookin for in the first post...
What would u grind? Small duration/big lift?

Idc where it makes the power I want... I just thought I'd have to spin it up to 7500 to get the full benefit of power...

 
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Brent Lykins, B2 Motorsports
(Login blykins)
72.4.3.130

Well, it's counterintuitive.....

August 7 2012, 2:52 PM 

...to have an engine that makes peak hp at 7500 and has low end manners plus vacuum to boot.

Modern engines can do it with multivalve heads, variable valve timing, EFI, etc. However, it's not like that with big cammed carbureted engines, especially small ones.

Where would you need to be to peak at 7500? Probably with .050" durations in the 240's. That may not sound big, but for a 302, it's huge.

Again, you'll need to figure out which side of the fence you want to be on. The streetable side with plenty of vacuum and some low end power (relatively speaking, Boss 302's don't have low end power), or a 7500 screamer with no niceties down low. I don't think you'll be happy with a 7500 rpm peak on the street, even with a 4.30 gear.

Brent Lykins
B2 Motorsports, LLC







 
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Brent Lykins, B2 Motorsports
(Login blykins)
72.4.3.130

BTW...

August 7 2012, 3:05 PM 

If it were me, I'd not worry about the vacuum and the "driving" part of the engine. I'd cam it to turn some revs so that it will be efficient and make some horsepower. A solid cam with about 240-242 duration @ .050", a 108LSA on a 104ICL, and about .600" lift.

In stock form with the Boss 302 cam (about 228 deg @ .050"), it should make about 375hp at 6600-6700. You could probably get closer to 400 with a little larger cam and a higher peak, but prepared for less and less torque. A stock 5.0 Mustang had more torque than these Boss 302's did.

Brent Lykins
B2 Motorsports, LLC







 
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Jim
(Login 69fstback)
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198.228.200.143

My old 03 Mach 1...

August 7 2012, 3:08 PM 

My old 2003 Mach was kind of like a boss 302 I believe... 4.6...
Made 320 torque at 4500... Peak hp was around 5900-6100... I shifted at 6600-6700...
It had 4.10s... Ran 12.70... I loved the feel of that car... Mellow then wham... Pulled for forever it felt like...

I think that's about what I'm shooting for... Not making peak hp at 7500... More like shifting around 7200-7400...
Peak around 6600-6700

 
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Brent Lykins, B2 Motorsports
(Login blykins)
72.4.3.130

Something around the factory cam would work then....

August 7 2012, 3:12 PM 

...I wouldn't use the factory specs of course, but just similar .050" durations. The other parts of the lobe would be more modern.

Brent Lykins
B2 Motorsports, LLC







 
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Dax
(Login snakefake)
Member
212.214.188.166

347 Boss

August 7 2012, 3:36 PM 

Hi, a former EMC winners have just built a 347 Boss for a friend. Stock 302Boss block, heads,intake.
This is the answer he got in the mail.
I ran the Boss engine on the dyno for several hours today- Everything seems fine, I worked with carburetor jetting quite a bit, and the engine picked up a little--- The best horsepower was jusy under 500 ( like 498 ) and the best torque was right at 445 pounds. The HP was still climbing at 66-6700, but that was as high as I revved it up. I will explain more details later when we talk on the phone===

Good luck with your build.

 
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Jim
(Login 69fstback)
Member
198.228.200.161

Interesting... The 347 only had to rev to 6700 to make that..

August 7 2012, 3:49 PM 

That build seems a bit over kill for me... But 445 torque is plenty...

My goal is 340-360rwhp
Torque well 320-330 at the wheels would be nice...

That should be a solid low 12 second car in my light package...
And be mellow enough to just cruise if needed...

Maybe the ticket is a 331... And only spin it to 6800-7000... (shift point) (have to get crank cut anyway)

 
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Brent Lykins, B2 Motorsports
(Login blykins)
166.147.120.154

That's the whole idea behind added displacement....

August 7 2012, 4:10 PM 

....you don't have to have a wild engine to make horsepower. Peaks go down and power either stays the same or goes up. You won't meet your torque goal with the 302, an't no way.

The 331-347 cranks are cheap. I would give it a lot of thought as grinding a crank is half way there. Of course if you go with a 331 or 347 you're almost at a 351.....hahaha

Brent Lykins
B2 Motorsports, LLC







 
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Jim
(Login 69fstback)
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198.228.200.161

331 it is...It's same price...

August 7 2012, 4:22 PM 

I'm gonna go with the 331... Spun to 7000...
Rpm has a cast crank for $179... Or 4340 for $356....
Rods are cheap enough...(super light I beams) (need them either way)
Pistons are off the shelf...

3.25 stroke should rev easier then 3.50 stroke...

Looking at 225/235 duration at 50... 550 or so lift on a 110 sound about right?
Also where can I get the cam? Is it just a regular 302 grind? Or I need something special..

 
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Brent Lykins, B2 Motorsports
(Login blykins)
166.147.120.154

Buy scat....

August 7 2012, 4:50 PM 

Skip the cheap stuff that needs machining. A scat 331 crank is $200. It's worth the money. You need more duration than that. Anytime you add displacement you add duration.

It would be a regular 302 cam.

The difference between a 3.25 and a 3.5 wouldn't be that noticeable to you. But when you add stroke you add torque.

Also, build the engine for the application, not just based around an rpm number.

Brent Lykins
B2 Motorsports, LLC








    
This message has been edited by blykins from IP address 166.147.120.154 on Aug 7, 2012 4:52 PM


 
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Joe D. Craine
(Login MsgtJoe)
Member
75.1.90.180

Boss 302 camshaft is a copy of ther 289HP but

August 7 2012, 6:03 PM 

uses the 1.73 rocker ratio to get the lift, duration. If you buy a NOS Boss 302 camshaft, it is stamped identical to the 289HP solid lifter cam. I have one here in the box. When you use 1.6 rocker arms, it is a 289 cam. I know this will start an argument, but unless Ford screwed up somewhere along the way, I have two of those cams and they are the same. Joe-JDC.

 
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Jim
(Login 69fstback)
Member
24.0.230.173

How's the comp nostalgia 271s look? Ran threw program and got these numbers!

August 7 2012, 10:05 PM 

Ran this threw a program and Used 1 5/8 headers and 750 carb.
Dual plan intake...
10.1 compression
Stock Cleveland 4v head flow numbers...

I came up with 394 hp at 6500 rpm and 379 torque at 4500...

I figure with larger headers 1 7/8 or 2" I be over 400hp... Probally same amount of torque...

Cam specs
225@050 intake
232@050 exhaust
532 intake lift
528 exhaust lift




 
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Brent Lykins, B2 Motorsports
(Login blykins)
74.134.96.147

You need more lift.....

August 8 2012, 3:47 AM 

Remember that that's gross lift. By the time you take .530" lift or so and pull almost .020" lash out of it, you're not gonna have anything left....hahaha

Use the Xtreme Energy lobes, and increase the duration....

When you add displacement, you don't go down in cam duration to get the same results...

The stock cam was 228° duration @ .050". You're adding 30 cubes. You're going to have to go up probably 10-12 degrees. Remember, engine sims are not always correct...

Brent Lykins
B2 Motorsports, LLC







 
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Jim
(Login 69fstback)
Member
198.228.200.146

BRent... Can u run the 271s threw your engine sim?

August 8 2012, 10:57 AM 

Hey brent can u run a 302 displacement and a 331 disPlacement threw your engine sim? Maybe I did something wrong.
I see on here you use software Like this alot and I'm new at it maybe I messed up.

Specs I used.

10.1 compression
3.0 stroke/3.25 stroke
Dual plane high flow intake
Stock 351c 4v cc heads
Light friction valve train (roller rocker titanium retainers)
Comp nostigila 271s cam.
Try 1 7/8 headers threw high flow mufflers.
750 Holley dp

I got peak torque 379@4500 peak hp 396@6500 at 302 displacment

331 was 392 torque@4000 peak hp 401@6000

 
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Brent Lykins, B2 Motorsports
(Login blykins)
72.4.3.130

Engine sims are good for comparisons between components....

August 8 2012, 11:53 AM 

I use EA Pro for approximations and it's usually 6-7% high compared to the actual dyno. However, it will let you see the difference between two components...such as two cams, an increase in compression, an increase in stroke, etc.

I will say that there's no way whatsoever a 302 will make 379 lb-ft of torque, much less at just 4500 rpm and still make peak hp at 6500...

For cam specs, I use past engine build and dyno experience based on all the stuff I've tried. I've built most of the engines that guys think about trying and engines don't have computer simulators or read magazine articles.

You have to use a little engine builder logic with some of this stuff...for instance, on heads that will do the best at .550" and .600" lift, you should use a cam with net valve lift in that range and use a lobe that will allow a good amount of flow at lower lift as well.

For entertainment purposes, here's EA's results based on your specs:

302 - 372 hp @ 7000, 313 lb-ft @ 5500.

331 - 379 hp @ 6500, 336 lb-ft @ 5000.

With increased displacement, you will need more cam. That's a standard result that you can count on and is reflected here by the peak hp rpm drop. With increased stroke, torque goes up.

That's why I'm not a fan of these engines...a 375 hp 302 can be done with a set of AFR/TFS heads and a much lower peak, with more torque to boot. My street/strip 347's with AFR 205cc heads and a mild solid roller on pump gas will make 490hp @ 6500 with a 650 carb and about 450 lb-ft of torque.


Brent Lykins
B2 Motorsports, LLC








    
This message has been edited by blykins from IP address 72.4.3.130 on Aug 8, 2012 12:26 PM


 
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