FE DYNO #s and Cam Selection

[SFfiredog]

Guys,
The engine is not in a Cobra
It is in a Shelby GT-500
No side pipes
I just dynoed (engine dyno, not chassis dyno) an engine with open headers and then switched to the Superformance sidepipes.
The engine lost 24 horsepower which isn't too bad but it lost almost 60 ft lbs of torque which is not so good.

--Mike

[Excaliber]

OK I forgot for a minute it's a GT-500 were talking about, BUT same principle applies. Wonder what "open headers" would reveal on THIS car?

24 horse aint bad at all on your sidepipes! I was astonished my loss was 96 and it's not like the sidepipes are "quiet" either!
Perhaps more loss is incurred with muffler restrictions based on cam, heads, cubic inch, overall horse power, etc. Engine dynoed at 667 horse with open headers on mine.

[Shelbytexas]

RED CSX1:
Tell me more about your motor, as this is the cam proposed by Kieth. Hydrolic Roller? Compression Ratio? Intake? etc. How does it idle? Vacuum? This would be very helpful!
Ken

[RedCSX1]

Excaliber, I mean Slick,
In your case I don't think that you will miss 93 H.P. with that moster you have under that hood of yours.

Keep in mind if you are running the Stelling Air cleaner you will lose some H.P. as well.

Shelby Texas,
I am running a Solid Lifter cam ground by Cam Research (303) 762-8196. 242/242@.050 with 590 lift. The lobe separation is 106. Because this is not wide pattern cam the idle is smooth. The intake is a ported Blue Thunder and the carb is a Mighty Demon 850cfm. The heads are 10.5-1 The intake valves are 2.19 Ferria valves (Chevy valves) and the exhaust are 1.75 SFI with a 5 angle valve job. The Rockers are stainless rollers, The Valves springs are crane and the keepers are Titanium. The push rods are large nascar type push rods. The Pistons are Ross forged flat top .030 with Chevy B.B. Piston Pins. and Lemans Rods. The Timing was set at 40 degrees. The motor was dynoed using 92 octane.

See my pictures gallery for pictures of the 427 motor

Hope that helps

[Jim Downard]

O.K., how's this for not bad. Bear in mind that I purchased an Indy Mustang 393w stroker and he sent it to me screwed up. I did get it fixed myself, but here's what I've got. 351W block, clearanced for a Scat 3.85" stroker crank, stock 351w rods, KB192 pistons (these are actually 289 pistons, but they work), Roush 200 cast iron heads with tiny bit of pocket porting, Comp cams 234/246 dur @ .050 and .541/.544 lift camshaft (nice lope), Edelbrock Performer RPM intake, and Edelbrock 700cfm vacume secondary carb., side pipe mods by DV (nice sound), Edelbrock pro flo air cleaner (flows 1000cfm, no difference on dyno if removed). It's a fairly basic motor, drives nice, but has a lean spot off idle I'm having trouble getting rid of. 360 rwhp @ 6250 rpm, 400 lb ft rwtq between 3250 - 4750rpm (not exact, but a really nice flat torque curve, and hp curve is a linear rise. I think these are respectable numbers for such a basic motor. Heck, in thrid gear with just me in the car, the rear tires will break loose on their own. That's enough for me.

Jim Downard

[Shelbytexas]

Thanks Morga & Jim
Ken

[Steve R]

Ken,
With a degree wheel and a dial indicater, you can determine the cam specs you have without tearing down the engine.
One question:
Did you drive the car hard? are you satisfied with the acceleration???
I did not read every word of the thread. If these points have been already made..... Nev-R-Mind..
Steve
P.S. was SF Firedog's question about a hydraulic cam in this block answered??

[DuckRyder]

Originally posted by Steve R


P.S. was SF Firedog's question about a hydraulic cam in this block answered??

I don't think so.

Could it be this is the WHOLE problem?

[Power Surge]

Here's my take on it...

First of all, let me use a very good example I had in my shop recently. It was an ERA with a 427 side oiler, stock stroke crank, out of the box Edel heads, cam VERY similar to yours, MR intake and 750 Holley. This engine was dynoed on an engine dyno by the engine builder and made 430hp. I dynoed the car on my chassis dyno, and it made 387 at the wheels. That almost exactly 10% drivetrain loss through the IRS jag rear. I use 8% for a manual trans with live axle.

Now if your car is only putting 300 at the wheels, something is def wrong, especially with the extra cubic inches. Even with the low timing, you should still have mega torque. There can be lots of causes, but we also don't know key things about the motor. If the CR is low, that'll hurt you. We already know the timing is low. The cam could be not degreed properly. We don't know the air/fuel of the tune. Did you get a/f readings when you dynoed? The one thing that bothers me about the whole situation, is that you say you blew a headgasket at 500 miles. I think that motor has timing issues. And by timing I mean cam timing as well as dist spark timing.

If you got a/f readings while on the dyno, let us know. Post a pic of the graph if you can.

[Shelbytexas]

Good questions. The guy that built the engine used to race - for a living. Factory 427 Thunderbolts / Cobra Jet mustangs, etc. He did specially prepare it to run a hydrolic cam. He seemed to have all the credentials to build a fine engine, but wasn't into roller cams for some reason - he said the lifters were very heavy and required extraordinary spring pressures and were only marginally better. This choice plus the choice not to work the heads, I believe cost RPMS, flow and the resulting HP.

The car felt fast in first, but just a little quicker than stock. For instance, just say you were going 75 down the freeway next to a Porche Carrerra (let's just say), at 3750 rpms in 4 the gear. When I dropped down to 3rd gear, it would bump to the high - mid 4000's, and fall off dramaticallly at 5200 rpm. Nothin' but German tail lights! So it felt kinda like the Dyno shows - it would pull pretty hard, but lose steam pretty quickly. For 14K, not a big improvement over stock at all...

[CSX 4027]

If you posted the actual dyno sheet, we could see if the steam it was running out of after 5200 was air, fuel or both.
Right now, it's just steam

[RICK LAKE]

Shelbytexas I have a 452 motor with a 501-533" cam. 9.2 compression 360hp 460 tork. My motor goes flat and 5200 rpm, This is what I built it for, big tork and flat hp curve. The heads where CNC by Mike L at Shelby and flow better than the cam due to size. I have a 6000 rpm chip in my MSD. Saves the motor. The cam is advance 4 degrees. I run 12.50's in the 1/4 mile. HP and Tork numbers are great for the bench racing hours but a cobra is limited by how much power you can get to the ground and that it is a flying brick. A porsche will fly by at 130 mph. Cuts the air a little better. With your motor, what where you looking for?? What are you going to do with the car?? Street rod, Car shows, Autocross, Silverstone race, or 1/4 beast? Cobra can do it all, but some thing it does better than others. My 2 cents Rick Lake

[DuckRyder]

Guys, The engine is not in a Cobra, It is in a Shelby GT-500

Just to get it on page4.

Shelbytexas, please be sure to post if anything is actually found "wrong" and the new numbers after Keith gets done.

[Shelbytexas]

Rick - the car is in a '68 GT 500 convert (3600 lbs). It's a pretty car, but I can't stand car shows for more than an hour, but would love to Autocross / 1/4 mile the car within limits of sanity. I hoped for an engine more like yours, but something that perhaps rev'ed a little higher - and somewhere around 375 rwhp. Tell me more about the cam you have and how the engine idles/etc.
Thanks. Ken

[RedCSX]

Ken,
When I built up the CJ 428 for my 67 GT-500. I was trying to have my cake and eat it too. Enough vac for the power brakes and a great motor. Some people warned me about to much cam. So I ordered a Com cam that was like 210 /213 @.050. The guy helping build the motor said it was to small and would fall on its face and he was Right. The motor had great bottom end and would get this lean feeling about 5000RPMS and start having a little miss above that. I tried to correct it by up jetting the carb and having the Carb worked over by Jet Performance and still did not cure the problem. Frustrating when you have so much money invested in a motor. It went 100 mph in the quarter, and I wanted so much more than that.

Morgan

[Keithc8]

I believe the first problem that Shelbytexas had was that the engine blew the head gaskets and that needs to be researched. The other problem is he does not want to spend a lot more money and this may limit what can be done. He told me the other engine builder drilled the block for the hydraulic flat-tappet camshaft. Till the engine is torn down we will know nothing. The engine may have lost a cam lobe. When we take it apart we can cc the pistons, check the deck height and cc the heads. A lot of people assume these heads are the 72cc that they are advertised at but are more like 75/76cc. I know the engine can be helped a lot with head porting and camshaft. The stage 2 heads we do will pick the flow up about 50cfm intake and 40 on the exhaust at least. With better head flow and more lift you can run a smaller duration camshaft to help the vacum and still fill the cylinders well. This is why good head flow and running a hydraulic roller that will have .625 lift to make use of the head flow works. I wish I had been able to do this engine from scratch. The exhaust on the car will also restrict the power some what. We are seeing more like 20 percent on the chassi dyno with most applications through the exhaust and drivetrain and I believe this is pretty common. I believe over 400HP and 400 ft/lbs torque should be no problem. Its all about time and money. We may have been able to tune more HP out of the engine if it had not blown a head gasket. These kind of deals are not any fun for anybody. I hope we casn help get the car running the way Shelbytexas would like. Keith