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  #16 (permalink)  
Old 08-27-2012, 03:34 PM
How fast is fast enough?
 
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As it sits, HEADERS AND EXHAUST should be on the top of your priority list. I realize they may not make headers for your car, but custom ones can be made by you or a shop. You can get a kit with flanges and bends to get you started. Through in some good merge collectors and dual 3" exhaust and you'll see some serious power increase.

Just remember air can only come in as fast as it goes out. Also, a strong clean exhaust pulse can really draw in a lot of extra air through the intake.

There's a lot of things you can do to your car to get you some power but your engine is already being choked by the exhaust.

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  #17 (permalink)  
Old 08-27-2012, 03:59 PM
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Quote:
Originally Posted by ap72 View Post
As it sits, HEADERS AND EXHAUST should be on the top of your priority list. I realize they may not make headers for your car, but custom ones can be made by you or a shop. You can get a kit with flanges and bends to get you started. Through in some good merge collectors and dual 3" exhaust and you'll see some serious power increase.

Just remember air can only come in as fast as it goes out. Also, a strong clean exhaust pulse can really draw in a lot of extra air through the intake.

There's a lot of things you can do to your car to get you some power but your engine is already being choked by the exhaust.
Thanks for that,will have a go at making my own headers then, im going to
change carb and advance cam, do you think I will get near 400 horsepower?
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Old 08-27-2012, 04:06 PM
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Quote:
Originally Posted by dave350v8 View Post
Hi
bogie and engineczar both of you are spot on! It does seem to at least match the camels at lower revs but then it wants to rev further than them!
The advertised duration is 280 and at .50 intake/exhaust is 230 degrees.
To be honest I dont fully understand these figures.

Skip whites website states with a cam around 480/510 lift it dynos at just over 400 horsepower on a 350.

Do you think changing rear gears and a bigger carb will help, I was considering a cam change as well if you have any suggestions?
Thanks again
Certainly a bigger carb say around 750 CFM on an Edlebrock Performer RPM intake with long tube headers of 1-3/4 or 1-7/8ths tubes combining Skip's deep breather heads with this cam, the engine ought to go to over 400 horses I guess somewhere from 5800 to 6200 RPMs. It's likely to be peaky; it also may take 1.6 rockers to get there.

This whole thing, and this includes the performance from your older camel humps, really gets the engine into an area where in a systems integration sense, sum of the parts and the tune, it can gain or lose gobs of power on incredibly small often seemingly innocuous changes/exceptions/deviations of things. So with a change, as the one you did with the heads, can make it difficult to dial it back in. You just have to mess with it and that could include as was suggested advancing the cam a few degrees, I havent used a Skip White cam so I don't know if he grinds them straight up or advances them as Comp and others do. So you've got to be a bit thoughtful here. Comps come with about 4 degrees already in them so sometimes adding more isn't helpful. I just don't know if Skip's cams are the same way of not. Like Jim Miller, he touches base in here sometimes maybe you'll hear from him about this.

Your cam numbers tell you that the valve closed to closed timing is 280 degees, SAE (Society of Automotive Engineers here in the U.S.) specify this measure at .006 inch lift, whether that is really done here I don't know. 230 degrees is the duration measure from the point where the valve opened to .050 inch and is .050 inch from being closed. The difference between these two points is mostly ramps to ease the lifter and valve train motion into opening smoothly without flexing the pushrod and sitting the valve down without bouncing it. The .480/.510 inch measure would be the amount of intake and exhaust opening, respectivly, over the peak of their lobes. This is valve opening not lift at the lobe, there is a rocker between these two places. For the Chevy Small Block this is usually given for a 1.5 to 1 rocker ratio. So the actual lift happening at the lobe would be 50 percent less or .320/.340 inch. A 1.6 to 1 rocker would add 1.067 to the 1.5 rocker ratio and lift so that lift at the valve would go to .512/.544 inch with this cam.

Stiffer gears would improve acceleration performance by increasing the mechanical advantage the engine has over the mass it needs to move. Plus, it moves the RPMs higher for any given road speed to where more engine power is available. So gearing is a double advantage in terms of power delivered between the tire and ground. The downside of stiffer gears is higher fuel consumption, noise, vibration and wear.

Bogie
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Old 08-27-2012, 04:52 PM
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Originally Posted by oldbogie View Post
Certainly a bigger carb say around 750 CFM on an Edlebrock Performer RPM intake with long tube headers of 1-3/4 or 1-7/8ths tubes combining Skip's deep breather heads with this cam, the engine ought to go to over 400 horses I guess somewhere from 5800 to 6200 RPMs. It's likely to be peaky; it also may take 1.6 rockers to get there.

This whole thing, and this includes the performance from your older camel humps, really gets the engine into an area where in a systems integration sense, sum of the parts and the tune, it can gain or lose gobs of power on incredibly small often seemingly innocuous changes/exceptions/deviations of things. So with a change, as the one you did with the heads, can make it difficult to dial it back in. You just have to mess with it and that could include as was suggested advancing the cam a few degrees, I havent used a Skip White cam so I don't know if he grinds them straight up or advances them as Comp and others do. So you've got to be a bit thoughtful here. Comps come with about 4 degrees already in them so sometimes adding more isn't helpful. I just don't know if Skip's cams are the same way of not. Like Jim Miller, he touches base in here sometimes maybe you'll hear from him about this.

Your cam numbers tell you that the valve closed to closed timing is 280 degees, SAE (Society of Automotive Engineers here in the U.S.) specify this measure at .006 inch lift, whether that is really done here I don't know. 230 degrees is the duration measure from the point where the valve opened to .050 inch and is .050 inch from being closed. The difference between these two points is mostly ramps to ease the lifter and valve train motion into opening smoothly without flexing the pushrod and sitting the valve down without bouncing it. The .480/.510 inch measure would be the amount of intake and exhaust opening, respectivly, over the peak of their lobes. This is valve opening not lift at the lobe, there is a rocker between these two places. For the Chevy Small Block this is usually given for a 1.5 to 1 rocker ratio. So the actual lift happening at the lobe would be 50 percent less or .320/.340 inch. A 1.6 to 1 rocker would add 1.067 to the 1.5 rocker ratio and lift so that lift at the valve would go to .512/.544 inch with this cam.

Stiffer gears would improve acceleration performance by increasing the mechanical advantage the engine has over the mass it needs to move. Plus, it moves the RPMs higher for any given road speed to where more engine power is available. So gearing is a double advantage in terms of power delivered between the tire and ground. The downside of stiffer gears is higher fuel consumption, noise, vibration and wear.

Bogie
Thanks Bogie for taking the time to explain these things to me! I will have to
read it several times to get it to sink in but I will get there!
The cam I have in at the moment is a compcams magnum 280 480/480 lift so
smaller than what skip white advises, and as you said this has already 4 degrees in it so I wont be advancing that!

The lightness of my car(2600lbs) should help me with the bigger port runners
then?
Thanks again
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  #20 (permalink)  
Old 08-27-2012, 05:00 PM
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Along with the loss of compression from going from a 60ish cc chamber to 64ccs, you have also lost perhaps a point of effective compression because you went from a cast iron head to aluminum head. If you want to stick with flat-tops, you would be better served with a cast-iron head, perhaps an EngineQuest Vor-Tec head with the manifold mating surface that matches your existing intake manifold.

tom
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  #21 (permalink)  
Old 08-27-2012, 05:28 PM
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Quote:
Originally Posted by machine shop tom View Post
Along with the loss of compression from going from a 60ish cc chamber to 64ccs, you have also lost perhaps a point of effective compression because you went from a cast iron head to aluminum head. If you want to stick with flat-tops, you would be better served with a cast-iron head, perhaps an EngineQuest Vor-Tec head with the manifold mating surface that matches your existing intake manifold.

tom
Not to hijack the thread but I just used a set of those on an inboard boat engine. I have to say I was pretty impressed with them. The quality of the castings was up there and even the valve job could have been used right out of the box. For my customer it was a win win because he was able to retain his cast iron intake and get the benefit of a vortec style chamber. The price was also a steal at $280 each bare.
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Old 08-27-2012, 05:40 PM
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You may want to look at swapping to this cam:Lunati 60104 - Lunati Voodoo Camshafts - Overview - SummitRacing.com you have the springs to handle the additional lift,this cam is designed to bring back some of the low and mid-range you lost with the 210cc heads please read the description at the bottom of the specs,as mentioned earlier do advance the cam 4 degrees,some rear gears in the 3:70's will be a big help too.
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Old 08-28-2012, 08:06 AM
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You may want to look at swapping to this cam:Lunati 60104 - Lunati Voodoo Camshafts - Overview - SummitRacing.com you have the springs to handle the additional lift,this cam is designed to bring back some of the low and mid-range you lost with the 210cc heads please read the description at the bottom of the specs,as mentioned earlier do advance the cam 4 degrees,some rear gears in the 3:70's will be a big help too.
That looks a good cam! Think it might be worth doing, thanks for your input!
When I build my next engine I will know a lot more for sure!
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