Do ya love yer sidepipes???

[undy]

Well.. I dyno'd the Cobra the first of the week. There's good and bad.. I'll talk about the good first. I gained around 70 rwhp by going from the Spiral Turbo inserts to the 3" Chambered Exhaust inserts, no other change. Temperatures were similar (within 5 degrees) and the same dyno was used. I dyno'd 370 with the Spirals and 440 with the Classics. Kudo's to Eric @ Classic Chamber for providing a quality product and the customer service to back it up!

Now for the bad... Even at 440 rwhp the motor's developing much less than it should. I can only assume that it due to my restrictive heads. I had Keith supply me with valves and springs but I had a local shop accomplish the port job and assembly on a set of Eboks that I already had. The port work looks great but I honestly believe that they flow no where near Keith's stage 2 or 3s.. There's just no other logical explantion. Now ..... do I want to spend another $3K for a set of stage 3 heads or just accept what I have now??

Dave

[496fe]

All FE's are restricted by air flow. You are trying to feed a 482-inch engine with an induction system designed for a 352!

Look at this:

http://users.erols.com/srweiss/tablehdc.htm

Read the explanation at the beginning. People make all kinds of claims about cylinder head air flow. The flow is only valuable with the valve opening within a certain range. It is definitely an art rather than a science. That is why it is better to get a whole package from somebody like KC.

The most you can expect with your late-50's designed engine and still be streetable on pump gas is in the area of 600-650 HP. This translates into about 475-525 at the rear wheel.

There is lots of good advise on this forum about getting that last 50 or so HP. I think you are on the right track with the KC heads. They turn out to be about $50-60 per HP. A ported single-plane manifold will be worth a few more ponies.

Good luck,

Brian

[undy]

Originally Posted by 496fe

All FE's are restricted by air flow. You are trying to feed a 482-inch engine with an induction system designed for a 352!

Look at this:

http://users.erols.com/srweiss/tablehdc.htm

Read the explanation at the beginning. People make all kinds of claims about cylinder head air flow. The flow is only valuable with the valve opening within a certain range. It is definitely an art rather than a science. That is why it is better to get a whole package from somebody like KC.

The most you can expect with your late-50's designed engine and still be streetable on pump gas is in the area of 600-650 HP. This translates into about 475-525 at the rear wheel.

There is lots of good advise on this forum about getting that last 50 or so HP. I think you are on the right track with the KC heads. They turn out to be about $50-60 per HP. A ported single-plane manifold will be worth a few more ponies.

Good luck,

Brian

Hind site, as they say, is 20/20.. Had I known that my heads were possibly going to be such turds I would have gone With Keith's stage II or IIIs in the first place. I just need to make up my mind if I want to spend the x-tra dough for them or not.

I wish I had the room for a Victor Jr.... The Blue Thunder MR 427 1x4 is the tallest one I can fit.

Dave

[496fe]

Dave,

During your decision-making process, consider that the Victor (not Victor Jr.) is slightly taller than the Performer. You need to also get a different air cleaner or modify your existing one to fit under the hood.

Summit has the correct Victor http://store.summitracing.com/partde...5&autoview=sku here.

My 496FE with 9.4:1 compression was dynoed at 609 HP with the ported Victor (about $450 for the porting and about $550 for the manifold). I replaced the Victor with the Performer and the car didn't "feel" as fast - I could definitely tell the difference. My SOP "dyno" test is how easily the rear tires light up by gassing it in second gear. The tires spin much more with the Victor.

The Victor changes the "look" of the engine from a street rod engine to a race engine also.

Food for thought.

Brian

[Rare Iron]

Originally Posted by undy

Well.. I dyno'd the Cobra the first of the week. There's good and bad.. I'll talk about the good first. I gained around 70 rwhp by going from the Spiral Turbo inserts to the 3" Chambered Exhaust inserts, no other change. Temperatures were similar (within 5 degrees) and the same dyno was used. I dyno'd 370 with the Spirals and 440 with the Classics. Kudo's to Eric @ Classic Chamber for providing a quality product and the customer service to back it up!

Now for the bad... Even at 440 rwhp the motor's developing much less than it should. I can only assume that it due to my restrictive heads. I had Keith supply me with valves and springs but I had a local shop accomplish the port job and assembly on a set of Eboks that I already had. The port work looks great but I honestly believe that they flow no where near Keith's stage 2 or 3s.. There's just no other logical explantion. Now ..... do I want to spend another $3K for a set of stage 3 heads or just accept what I have now??

Dave

Dave I have to ask you, did you have the center tube uncapped at both ends of the spiral inserts? This would permit significantly more flow through the sidepipe than if one end was capped from what I understand.

-Eric

[undy]

Originally Posted by Rare Iron

Dave I have to ask you, did you have the center tube uncapped at both ends of the spiral inserts? This would permit significantly more flow through the sidepipe than if one end was capped from what I understand.

-Eric

Eric,

No, the caps were in place with 1/2" holes in them. I'm sure if I removed the caps my rwhp would have been higher though. In retrospect I probably should have removed them first and re-dyno'd. I might have been able to save myself some money.

Dave