Need 351W design

David Biele · #1 (**permalink**) 11-23-2002, 11:53 AM

I just ordered a new JBL and I need to decide on the Engine. I thought I would tell everybody what I am looking for in performance and let the CC forum help spec the Engine. If the CC forum can come up with a design that most of the members can agree on "I will have it built and dyno and report the results for everybody to enjoy".

First: The car will used on the Street and also ran at Willow Springs
Second: I do not want to add octaine boosters.
Third: I am looking for that acceleration that keeps your friends talking about there ride in your car.

Gearing. I am planning on using a 8.8 3.73 rear end with a tko 5 speed.

Top end: I don't want to install wings.

I hope everybody will enjoy this discussion.

David

Cobra #42 · #2 (**permalink**) 11-23-2002, 12:20 PM

The most important item, what's are you willing to spend ?????

Carroll DeWeese · #3 (**permalink**) 11-23-2002, 12:23 PM

By the way, a great book to read is "Ford Windsor: Small-Block Performance" by Isaac Martin. It covers parts and modifications for high performance street and racing. One of the engines that he covers is Vic Edelbrock's 351 street buildup. The book is a good start to become aware of the options for modifying your 351W.

David Biele · #4 (**permalink**) 11-23-2002, 12:46 PM

Oh yes, That is very important.
I would like to try and stay around 10k.

David

Jack21 · #5 (**permalink**) 11-23-2002, 02:33 PM

About $6k + - should be enough.

Why reinvent the wheel. Go over to the Airflow Research website. They took a Ford SVO crate 393W shortblock, tweaked the cam with a slightly warmer CompCams Hydraulic roller, bolted on a pair of their 185 heads, and dyno'd it. 509 HP, 537 FPTQ. Not a typo, that's a "5", not a "4"! The carb was a 750 Demon DP. (By comparison, the original 427 8V installed in '64 - '65 Galaxies & Fairlane 500's [and some Cobras] were rated at 425HP, and 470FPTQ with 11:1 compression. The 428 "Police Interceptors" fitted to most street Cobras were rated at 335 HP, and 480FPTQ).

Widowmaker · #6 (**permalink**) 11-23-2002, 03:26 PM

I would not go any lower (higher numerically) than a 3.54 rear end ratio. I have a 3.54 with a 393 inch engine and with the amount of low end torque that I have, first gear with a Tremec TKO gets used up in a hurry. Going to a higher rear end ratio would make 5th gear almost useless except for high speed touring and I'm sure that none of us would want to do any of that.

pbrown · #7 (**permalink**) 11-23-2002, 04:01 PM

If you want to build it yourself them this is how I did it. Otherwise, consider buying a crate from Ford Racing or Southern Automotive.

Here are the specifications for my engine:

Parts:
1994 351W block from Ford Racing
Ford Racing 393 stroker crank
Eagle ESP H-beam rods
KB Hypereutectic pistins for a 302 w/ 22cc dish
Melling high volume pump
Edelbrock Performer RPM heads w/ 60cc chambers
Edelbrock Performer RPM cam and lifters
Edelbrock Performer RPM Air-Gap intake manifold
BG Speed Demon 750CFM mech sec carb
Comp Cams Pro Magnum 1.6 ratio rockers
Edelbrock timing chain
Edelbrock water pump
MSD Billet distributer w/ vaccuum advance
MSD wires
Blue Thunder main stud girdle
Blue Thunder timing chain cover
Canton Racing road race oil pan and dipstick
Powermaster one wire alternater
March alternator bracket and pulleys
Ford Racing steel billet 157 tooth flywheel
Ford Racing crankshaft damper (needed $70 march spacer

)
ARP 12 point fasteners everywhere

Machine work done:
bored .030 over
block clearenced to fit stroker crank
crank fully balanced
pistons - valve clearance
pistons balanced
complete rotating assembly balanced with damper and flywheel
crank cross drilled for better oil flow
heads had a full reworking even though they were new

All of this cost a total of about $9500. The machine work was outsourced. The assembly was done by me. It's designed to run on pump gas and produce about 430 HP. Compression ratio is 9.85:1.

Things I would change if I did it all over:
higher volume heads so that I could use a forged piston. The 60cc heads with the stroker crank required a large dish in the piston. KB was the only one I could find without going custom. I would use a roller cam. That's good for about 10-20 hp over what I have.

Excaliber · #8 (**permalink**) 11-23-2002, 04:53 PM

I'd go 3.5 rear ratio myself, but you could make a strong case for a 3.7. Either one is still "to" low, but I love to just "fry" the tires sometimes! The 5 speed is an excellent choice (by the way, so is the JBL).

I'd want the lower 5th OD ratio, I think thats the .6 NOT the .8? I had the HIGH 5th gear, TO dam high! Depending on the cam you could be in a low rpm range at "cruising" speed the motor will NOT like with that high 5th gear. So a low 3.7 rear might be the ticket!

351W built right, as suggested above, will be plenty power to require a glove box holding a change of underwear (that's what it for you know, lol).

Ernie

pbrown · #9 (**permalink**) 11-23-2002, 06:05 PM

Use ~=3.5 rear diff and a TKO II tranny. The TKO II has the road race gear ratio with the .83 fifth gear.
The .68 version is too tall for anything other that highway crusing.

Ron61 · #10 (**permalink**) 11-24-2002, 05:49 AM

David,

I have the 8.8 rear end with a 3:27 ratio and I like it. I can break the tires loose in 2nd and 3rd when cornering real easy but I think you might like the 3:5 ratio a little better. Really have to be careful when getting on it for the start of the straight stretch. Now I just drive it as a street driver with street tires and it is great.

Ernie,

Ok which is it. You state the .8 spilit is to high and the following post says it is the .68. I think I have the .8 and it is way to high for anything but freeway crusing if that is what I actually have. It kicks my 3:27 ratio to around 2.10. I hardly ever use 5th gear even on the freeway. I guess I could go get my Tremec manual and look as it tells but I am to old and lazy to do that.

Excaliber · #11 (**permalink**) 11-24-2002, 09:32 AM

Ha ha,,,hey it's easy to transpose the numbers! The bottom line is the .6 is To high. Lets see, smaller number = higher gear ratio.

I think the "the high one" (.6?) is TO high for ANY gear!

Ernie

Ron61 · #12 (**permalink**) 11-24-2002, 10:05 AM

Ernie,

You are right as usual. I went and got my manual and I have the .6 split and not the .8 as I stated above. I know when I ordered the transmission I wasn't sure and after I got it in I knew I had gone the wrong way. With that .8 kicking my gear ratio up to around 2:10 I can't even break through the wall of air to get near my power band. So as I said above, most of my driving is in 4th gear. I did try one time in 5th and got it up to about 115 MPH at around 3200 RPM and the car just bogged and bucked against that wall of air. Went back to 4th and went right on past it. I do use 5th when I have to drive on the freeway as I can do 70 at 1900 RPM. I should have checked with someone who knew what they were talking about when I built my car in 1996.

Lew the taxman · #13 (**permalink**) 11-24-2002, 12:07 PM

I have a SPF with a 392 Ford crate engine and a Tremec 5sp, .68 5th & 3.73 rear. Not the best setup for street or track. Go with the Tremec II road race(the powers to be say that you don't need a TKO in a cobra). It has the harden gear set with the .83 5th. Then go with the 3.08 rear end. You get the same rpm=mph in 5th. But you stretch out 1 thru 4. Makes for a very nice close ratio tranny that will stay up to street and track work.

I'm with Jack21. I'm going to swap out the GT-40 heads for the AFR 185s, and Speed Demon carb. They say 75hp gain. Even a 50hp gain would worth the swap.

Lew

Andy Dunn · #14 (**permalink**) 11-24-2002, 01:20 PM

I agree with Carroll reading Ford Windsor: Small-Block Performance and I would also highly recommend Official Factory Guide to Building Ford Short-Track Power

This is a cobra, and so, for $10k, I think you'll be wanting 500-600HP

Engine #1 408ci (strong street)
500+ HP and big TQ

COMP.....10:1
HEADS.....AFR 205
CAM........COMP 282HR
CARB.......HOLLEY 750 double with mech secondaries
INTAKE....Victor Jr
STROKE...408 stroker kit
CRANK.....regular

Engine #2 357ci (radical street)
575HP and she screams

COMP.....10.5:1
HEADS.....TEA or BENNETT ported stage3 TrickFlows
CAM........CRANE 448601
CARB.......RACE DEMON 750
INTAKE....Super Victor
STROKE...stock 351
CRANK.....forged

for rotating assembly, I would check out Scat. They seem to always have the bet stuff.

Here is a hot engine you might dig. In their occasional MMFF ads, BENNETT advertises a 383 pump gas, 575HP, $9,995.

hope this info helps

Andy

Richard Hudgins · #15 (**permalink**) 11-24-2002, 07:17 PM

Hi David.

I think that if you look at the power curves for most 351 based (I am speaking of units that have a cam like the COMP 282HR) engines, you will see that they really do not start to run right until about 2800-3000 rpm.

Of course you can drive them down in the 2000 rpm range, but they are pretty dead. Therefore, please look at the info below to see the speeds in gears at 3000 rpm for both the 3.73 and 3.53. (I know, it should be 3.55.)

Now let us look at typical cruising speeds in SoCal.

Not much difference. is there?

But, at Willow Springs at 6500 we find the below.

Still a bit of a toss up as to what gear to run at Willow. the 3.73 will be better on a cold day and the 3.55 better on a high grip day.

Therefore, the racers conundrum. What to do, what to do?

The very best thing is to have a 3.27, a 3.53, and a 3.73 center section in your garage and on your trailer when you are at Willow.

Hell, it only takes about 30 minutes to change out the center section on the JBL.

But this is excess for most folks.

If you will send me your email address, I will send the program above to you by email if you would like, (It is only 225K) and you can ponder the ratios on your own.

PS. I like the 3:73. But, then again, a 3.55 is good to.

jwinkler · #16 (**permalink**) 11-24-2002, 08:57 PM

Sorry - no pertinent info to offer currently, just wanted to keep an eye on it as it progressed.

JLW

pbrown · #17 (**permalink**) 11-25-2002, 02:45 PM

The 351W strokers are not much good at high RPM racing. I wouldn't trust it much beyond 6K. The 351W also has a 3" main which sounds good when your thinking about engine strength but isn't good for high RPMs. Consider building something with the race block which has 2.749" mains. This is what you would find with a Cleveland but with the ability to use standard 351W parts.

Some possable Ford Racing blocks:
M-6010-M351 9.2 deck height
M-6010-N351 9.5 deck height

The 9.5" deck height is the same as a standard 351W block so you would have more choices for intake manifolds. Get a good forged crank with a stock stroke and you'll be able to run with the best of them.

JLW - FYI, there is a link at the bottom of the page that you can use to subscribe to the tread without posting. I use this feature often when I just want to follow along.

Curt C. · #18 (**permalink**) 11-25-2002, 02:59 PM

When selecting the gear it is important to keep in mind the rear tire size. Cobras can run a larger diameter tire than most mustangs. I run a 27 inch tire with 3.90 gear. This approximates a 3.73 with the smaller mustang tire - 26 inch??

Lew the taxman · #19 (**permalink**) 11-25-2002, 04:12 PM

A P.S. to my earlier reply. The gearing that I proposeed is with 315x35x17 or equal. That size tire is 25.7" in diameter. If you use a taller tire then go with the 3.27.

Lew

David Biele · #20 (**permalink**) 11-27-2002, 01:49 PM

I want thank everybody for the input. I guess there is many ways to go. I do like the 393 SVO engine with the aftermarket heads and cam. The rear end and transmission can be decided upon a little later.

Happy Holidays everbody.

David