351w stroker advice needed

[Wayne Maybury]

Draco

I live just outside of Montreal so you are only about 2 hours away. Come by any time, just contact me first to make sure I will be home. The car is all apart right now so don't expect me to be able to fire it up. I go to the F1 race every year in June, I think the CART race is scheduled for September.

The main reason that I went with the Performer RPM was that the Airgap was only available for Chevies when I bought mine. The airgap for the 351W came out about a year later. I have been thinking about changing for an Airgap but I had other upgrades higher on the priority list.

Overall engine height can be a potential problem with these cars. I bought a beautiful cast aluminium oval air filter from Finish Line only to find out that I couldn't make it fit without making some serious modifications to the hood and/or the filter. Paula was very understanding and took it back and supplied me with a much smaller round chrome filter that fits quite nicely.

Wayne

[Jim Downard]

Hey Jack21, I guess when I bought my car from Classic Roadsters back in 1990 they must have goofed. I told them that I fully intended to install a 351W from the outset and that the frame and motor mounts needed to be sent out for such an application. I currently have the regular Edelbrock Performer intake with an Edelbrock tri-oval aircleaner cut down as far as possible and I have only 3/4" of clearance between my air cleaner and hood. I guess 12 years later I have found out that the old Classic Roadsters screwed me on yet another detail.
I've met Ed at Classics by Elite several times, and the issue on the sidepipes has already been remedied. If you look on Ed's website, you'll see photo's of the mod's he performs on these sidepipes. The photo's you see are of MY old sidepipes being hacked up. I do LOVE the difference.
Thanks for your advice and input.

Jim Downard

[Jack21]

Jim,

Unfortunately, CR uses the same frame mount for both 302, and 351W and get around it by recommending builders only use the Lo Po Ede intake. Although the 351W is arguably the most popular, and commonly used engine, CR insists on sticking to its old ways. Also, the factory 302 frame mounts are rather flimsy for a healthy 351, much less a 393 or larger. CR only makes HD frame mounts for big blocks. The 351W needs different mounts than the 302.

I went so far as to send CR my shop drawings, and cardboard mock-ups of the 351 mounts I had made to use with the ES poly mounts. FREE! Not even a thanks, and no change to the factory mounts.

If you know Ed, get a set of his 351 motor and trans mounts. Intakes are easy to change now or later. Ede also makes 2 air cleaners that provide good hood clearance, their Pro-Flo small triangular with the foam element, and their oval (7 1/2" x 13 1/2" x 2 1/2") single 4 bbl.

The plastic MII firewall clutch cable mount can break and flex your firewall, and you'll tear your hair out trying to keep your clutch adjusted. Grafting a late Mustang aluminum quadrant onto the CR clutch pedal is easy to do. The late Mustang aftermarket clutch cable and firewall adjuster then work. You'll need a small aluminum "Puck" to mount it to the firewall. Much stronger and slicker cable, and it adjusts from the firewall. I have a Centerforce clutch and can depress the clutch pedal with my hand.

They make a great car, but they remind me of dealing with IBM way back when. If they didn't invent it, it doesn't exist. And CR isn't big on product upgrades and end-user suggestions. I hate to bash CR, but if it weren't for DV, and Don Scott doing this for free, there would be very little tech support for CR. Compare this to other vendors that jump in if a builder has a problem with suggestions, solutions, and current upgrades. They watch these posts and respond from factory people; even with other brands. Bob Putnam who I believe is CEO of ERA regularly chimes in here. Folks from Shell Valley frequently contribute also. I don't recall ever seeing a post from Gary Rutherford or Pete Johnson on this forum.

[Andy Dunn]

Hey Jim, here is what you engine will look close to on the dyno. I found your cam model here #292H
http://www.blueracer.cranecams.com/ford.htm

and here is the detailed spec sheet on it
http://dab7.cranecams.com/SpecCard/D...1=Display+Card

at the flywheel it looks like the peaks are
422HP@5500 and 468TQ@3500

you've got a big fat torque band that will kick you right in the pants



Big torque is more a function of stroke. Big HP is more a function of heads and rpm. A 358 can be 750HP at 14:1, with a 8000rpm screamer cam and massive flowing heads. It can be 650HP using 12:1 with a screamer cam and big heads. It can even be 620HP on pump gas with serious ported heads and 7500 screamer cam.
http://www.cobralads.com/desktopdyno/620hp.gif

From most of the posts I've read on the cobra boards, 90% of people prefer the big torque engines. They have a lower powerband that you feel in everyday driving. The car feels faster and accelerates like a mad dog. Most racers prefer the opposite. Piles of 2000rpm torque is not that useful on a road course and tricky to use since there is so much of it. Instead they prefer to get higher HP at the trade off of less torque. The car is then driven in the higher rpm ranges where the throttle is easier to control.

The drawback with strokers is that as you increase stroke, you increase the piston sidewall loads to a greater and greater degree. This robs power due to higher and higher levels of friction. It can also cause the piston to be less efficient at sealing the chamber. The piston is travelling a greater distance and moving at a faster rate so strokers tend to have lower redlines to keep piston speed in check.

The drawback to screamers is that you have to create parts that can handle the forces that come with 7500-8500 rpm. You have to use a flat tappet cam or solid roller since hydraulic rollers lose the ability to function. Lightness becomes important. Screamers tend to feel sluggish or flat down low in every day driving since they are outside their powerbands which are shifted right on the graph.


Andy
http://www.cobralads.com

PS want to see some wild heads? Jason FFR 1976 turned me onto a shop that does custom programmed CNC porting of all the major head lines.

TOTAL ENGINE AIRFLOW
http://www.totalengineairflow.com/pr...head/index.htm

How about a set of TrickFlows (TW not Rs) flowing almost as good as a set of Yates how about 313 / 254
http://www.totalengineairflow.com/pr.../afr/index.htm

[hound dog]

Andy,
Don't you just love that program?
h dog

[Andy Dunn]

hee hee hee. Houng Dog, I love it. I've learnt more about the internal combustion engine in a few weeks than I did in the last 20 years. It is such a great learning tool. I highly recommend that all cobra owners order it tonight!

http://www.motionsoftware.com

[CMansfield]

Jim,
I am just now getting back on line, checking back, traction should be your biggest problem, but then there is nothing like going WOT in second to about 6krpm and just barely maintaining traction the whole way. I am running 9.5-1 but it looks like some very knowledable individuals who know a lot more than I do have responded above.
Hope you get it on the road soon, your gonna love it. I couldn't pass up a 85 mile run today even tho I had to put on my ski clothes
Chas

[Jack21]

Coupla comments on your engine profile. Use Desktop Dyno myself, and used it to spec the engine I'm using now.

If you're building a 393, the stroke needs to be 3.85".

If you're using iron Windsor Sr. heads, make the CR 9.5:1. Aluminum, go with 10:1. (My actual with the TFS's came out to about 9.75:1 - no pinging on pump gas)

For a 393, a 750 CFM carb is good. For a 351, might want to use the 700 Holley, or 650 Speed Demon (which supposedly is good for about 680 CFM).

For a small block, even a big small block, run the program with small tube headers and mufflers. CR primaries for the 351W are 1 5/8" ID.

Correct me if I'm mistaken on this, but that Wolverine cam is a hydraulic flat tappet, not a roller. Try plugging in some of the current hydraulic roller grinds from Comp, Crane, and Crower and see what you get.

One of the things that grabbed me when I profiled the 351 side by side with the 393, and no other changes was the 393, at 2000 RPM was putting out 50 more fp/tq than the 351. At 5500 RPM, the 351 caught up to it. Enlarge the intake valve on the 393 to 2.08, and the 393 gets its top end back. Then add the 750 CFM carb, and the 393 starts using it.

Just for fun, bolt a set of 351 Cleveland 4v heads on the 393 (2.19/1.73) and see what happens.

[Andy Dunn]

Jack, you are right on that cam...my mistake. It is a non-roller. Sorry about that. I'll have to try it as a flat tappet. I think we are mixing two engine requests perhaps. Draco was originally interested in the 393 and Jim asked about a 358 and so I was trying to follow his specs. A 393 would have a stroke of 3.85 for sure. Here is a chart I made a while back with all the stroker possibilities I could find at the time and their bore and stroke. I think it is fairly accurate. It is missing a couple of new ones I have found. I think the 396 is in error. And the 416 was an odd ball kit I found on some site. You could add 383 to the list at 3.75 x 4.03 I guessed at possible redlines and they might be on the conservative side.



I would also agree with your carb suggestions. The 750 is a little large on a 351 and 357. Here is a link people have posted a few times in the past which helps estimate the proper carb.

http://www.prestage.com/carmath/calc_AirCapacity.asp

ok Jim, I re-ran and corrected my cam error and select flat tappet. I through on a 650 for the heck of it. Here are the results. This time I also included the table. Please also note that I guessed your heads based on the final number you listed. I picked heads with similar top numbers.
http://www.cobralads.com/desktopdyno/jim2.gif


Andy
http://www.cobralads.com

[d boothe]

Andy...don't you have mufflers on that thing??? If you do...please subtract 40-50 hp and almost the same amount of torque! I was running a 351W bored to 363...stock stroke, stock bottom end. I had a comp cam 280H....512 lift and 230 duration across the board...just about the same as your cam. I had ported 1970 heads, roller rockers, Edelbrock Perf RPM, and holley 750. The torque was ungodly....would really come on from 1500 to 4000 rpm. This was horrible at the autoX!!! WAY to much torque. I called Comp and they suggested a 282XE cam...523 and 517 lift...236 and . 244 duration at .500. I also added AFR 165 heads worked by Ed Curtis at FTI...they flow awsome. My setup now is much more controllable at the autoX...but still very strong on the street. With the rest of my setup unchanged...I show 398 HP and 388 ft lbs....with small tube headers and mufflers. If you stroke it...the HP will increase a little...the torque will increase a bunch. Just my $.02. dino

[Andy Dunn]

all great points Dino. Mufflers? We don't need no stinking mufflers. Caught me again. I am about to be disbarred from desktop dyno operators of america. Slap on small tube headers with mufflers, the new stats become
378HP@5500 431TQ@4000

and with large tube headers and mufflers
387HP@5500 443TQ@4000

Here is a question for everyone

Do you think that cobras with "open sidepipes" OR "glasspacks" are closer to "muffler" or closer to "open headers"... in terms of performance and proper choice in the engine software?

[Jack21]

Andy, thanks for the link to Total Engine Airflow. There's a lot more options for big Windsors than I was aware of. Makes the 393 even more attractive.

[d boothe]

Andy...I use the small tube headers with mufflers. I have an FFR with shortie headers and the "J" pipe...so I guess I would be closer to accurate with what I'm using. If your kit uses headers, just figure small...or large tube (you can measure if ya want!) with mufflers. I think every kit produced for the street has mufflers of some sort. Oh, and by the way...my 397 HP would jump to 437...and my 393 ft lbs of torque jump to 408 using the large tube, open header theory!!! Boy...wish it were so!!! dino

[Andy Dunn]

Hey Draco and Jack
I just re-read the posts and it seems like its going to be a 393 come hell or high water Here are a couple 393s to tempt you with. I went a conservative 9.5:1 on compression and a conservative shorty header with mufflers on exhaust. Then I went radical on some hydraulic roller cams. Victor Jr heads since they flow great and are priced well. 750 carb. Engine A is for the lads that love that monster large, flat and early torque curve to rip the lips off their face from 0-60. Engine B is for the lads that prefer a little less TQ and a little more HP for cutting a path at the local autocross and road course. Enjoy

http://www.cobralads.com/desktopdyno/393a.gif

http://www.cobralads.com/desktopdyno/393b.gif

Engine A's stats
434HP@5000 488TQ@4000

Engine B's stats
436HP@6000 413TQ@5000

A's Cam
http://www.cranecams.com/motorsports...ler/449761.htm
http://dab7.cranecams.com/SpecCard/D...1=Display+Card

Bs Cam
http://www.cranecams.com/motorsports...ler/449581.htm
http://dab7.cranecams.com/SpecCard/D....asp?PN=449581

Please note that I think it is a good idea to first talk to a cam manufacturer's Tech Support line before making an engine decision like this. Here is Crane's 386-258-6174

I just noticed a error in my research. CamA wants at least 10:1 and CamB is out of the pump gas range with 11:1. Let me see if I can find a substitute. Here is a quick engine C with cam 449651

Engine C's stats (10:1)
456HP@6000 462TQ@4500
http://www.cobralads.com/desktopdyno/393c.gif

at 10:1, engine A moves up a little to 446HP and 497TQ

Draco, I see you are going to check out Speedomotive. One of my favorite kits there is their long rod 372W. You might check it out and see what they think about it. It is a nice 448HP @ 6000 and 455TQ@4500. Sweet graphs and a slick little engine.
http://www.speedomotive.com/Ford%20351w%20to%20372.htm


Andy

[Jack21]

Andy,

This is the point I was at when I was doing my engine. The 372/377 was the popular stroker (there was no 393 yet) using an offset ground stock 351W crank, Mopar small block rods (6.125), and Chevy pistons. At the time, I had available $$$ to do the stroker or the roller cam, but not both. The roller won, hands down on Desktop Dyno, and that's what I built.

Have always tended to slightly overcam an engine, and always wind up kicking myself with a balky engine in the 1000 - 2000 RPM around town cruise range. A little technique I found to restore the bottom end was to install Rhoads variable duration lifters. (rhoadslifters.com) They machine a small channel in the lifter body to let the lifter bleed down slightly at low RPM. An engine running a set of these sounds like it has a solid lifter cam in it. The lifter reduces cam duration by around 6 - 10 deg at idle, and pumps back up to full duration at about 3000 RPM. Big block Pontiacs & Oldsmobiles with healthy cams responded well to these. Rhoads doesn't make their own roller lifters yet but will do the lifter modification for me. I'll send them a set and see how they work on the Windsor.

One of the things these sessions are showing is that the 393 stroker mod puts out the hp & tq, but they need slightly better breathing than the unstroked 351 or the top end goes away. Fortunately, the aftermarket has responded to this with better breathing heads. The bigger, 2.08/1.60 equipped TFS, AFR, Ede, heads are just the ticket.

The beauty of this is the extra cost of the motor is the replacement crank for about $500, depending on where you get it. Speedway Motors seems to have the best price to date, and offers the whole rotating kit for $1100. The stock 351 rods can be re-used if desired. KB now has a piston specific for this (KB#364).

Your engine A would make a hot street motor. Look at the torque curve. Nice and flat from 2000 - 5500, and doesn't dip under 450 fp all the way across. Try running it with the TFSR or AFR205/225 using the 2.08 intake valve. The cam is at the upper edge of the envelope for a street cam. Try a 224/234, and I would even use Rhoads modified lifters in this for better street manners.

Your engine B, you would hate on the street, but love on the track. Powerband is right where you want it. Be thinking forged crank, rods, pistons, 4 bolt main caps, and a valve train that will stay together at 6800.

For those of us following the sidepipe chronicles, and upgrading the sidepipe mufflers with a good set of glasspacks; run the simulation with mufflers, and again with open exhaust. Halfway in between should be the actual value.

With this kind of power available in a 351 sized envelope, and the weight of an iron head 302; why a big block?

The original question on this post was regarding Classic Roadsters 302/351 frame/motor mounts. Put one of these beasts in it, and you'll break them. Go see DV, or Don Scott for a set of the right 351W frame/motor mounts.

[Draco]

Well Andy it's not hell of high water but sure is begining to point that way. What seems to be the advantage of the 372. The cost is comparable to a 393 but it looks like you are running higher rpms to achieve the same results ( am I seeing things correctly?). Thanks for the links, this is great stuff, its keeping me up all night. Loved the foam/door trick! LOL.

Jack21

Could you have solved the low rpm problem if you had initially chosen a different cam and been able to cruise without the comprimise to HP and TQ?

DRACO

[Jack21]

True, the cam, a Comp Cams 224/224 retrofit roller is a little stout for my driving style, it was available in a retrofit roller grind when the engine was going together. Today, there are a lot more options. It's right at the 800 - 1500 RPM range that it's a little balky. Past that, and it pulls like a diesel.

Ford engine upgrades are getting to be like computer upgrades. No sooner is the engine out of the shop, and it's obsolete. The 372/377 of a few years back was the Pentium III for 351 motors. Not to mention engine machinists, who tend to be conservative, taking a dim view of mixing Ford, Chevy, and Mopar parts in an engine; and making it work. Am surprised it's still being offered for sale. The Scat stroker crank is the Pentium IV for 351 motors. It was designed around stock 351 rods, and stock 302 pistons. No machining headaches, no balancing headaches, no mix & match parts. Drops in, buttons up, and makes gobs of torque.

So what will the Pentium V look like? Blue Thunder just introduced an aluminum Cleveland head that offers breathing for 400 inch Windsors, but there's the monkey motion (like the 400M crank) of adapting it to the Windsor block. And they're expensive! Somebody; TFS, Ede, AFR, Canfield, will introduce a Cleveland style canted valve head that will bolt right up to Henry's truck & boat motor, use off the shelf C4V intake (carbureted), offer a C style lower EFI for 302/351 variants, use off the shelf C or W valve covers, and either W or C exhaust. And cost about $1,200 a pair. When? Within a year. Takers?

[Andy Dunn]

Hey Draco
I think Jack said it best in his post #35. Engine 393a is an engine that the vast majority of cobra owners are going to love on the street. It is going to feel and accelerate very fast. It is going to pull from 1500 and up. It is going to be super quick for 0-60. It will terrify you, your "friends", and the "import tuners" sitting across from you at the stop light The speedomotive 372 and engines B and C are not going to feel fast in the city. They will feel sluggish or flat. They are however, going to feel great at an autocross or roadcourse. Check out Dino's post again and you will see how tricky it is to manage a mountain of torque at low rpm in an autocross situation
http://www.clubcobra.com/forums/show...600#post117600

you will see some of these same comments reflected from Gordon Levy where he states "Many are destroking engines to get higher hp, lower torque, and higher reving engines. A lower torque engine is much easier to drive quickly on a road coarse than a high torque engine."
http://www.clubcobra.com/forums/show...097#post107097

I tend to side with Dino and Gordon on this issue since I won't be driving my cobra on the street that often. This is why I like the 372. Again, the majority of owners will prefer engine style A with a broad, flat, early high torque curve. Really this is splitting hairs...engine A would be very fast when used 3-4 times at cobra track events. Engine B might be only a second or two faster per lap. Engines are a trade off and so you should pick one that matches your personalilty and what you want out of your cobra.

Here is a link I stumbled across last night that is sort of related to this topic. Ever wonder what an engine designed for ovals would run in he quarter? Here is a story of a nascar running down a drag strip and how it would do. These engines are designed for 725HP but in a very narrow band to run at 200mph.
http://www.circleracingonline.com/fe...cardrag_1.html


Andy

[750hp]

Andy, what a letdown for the Nascar guys I bet they thought they'd be A LOT faster than that.... Kinda makes the World of Outlaws Sprint Cars all the more impressive. They've run the 1/4 in high 8 second times!!! If you ever have some spare time, is there any chance of giving my engine specs a run on your program? I haven't ever seen that software for sale over here.

[Jeff Frigo]

Craig:

Sprint cars in the high 8's? I think somebody must be high. How does a sprint car without a clutch stage, do a burout, etc.? Guess what, no transmission either.