331 curiousity
04-01-2009, 08:02 PM
#31
6th Gear Member
Join Date: Feb 2005
Location: KY
Posts: 13,396
You are putting way to much importance on a mathimatical figure (HP) and not enough on what really moves the car and that is torque. I never said I wanted to build it but telling the guy the best way to build what he has to work with. You can take two engines of the same cubic inch, with the same compression ratio and they will make pretty close to same amount of torque (I didn't say exact) but with a cam swap you can move that torque band around. With a smaller head (which he has) his best bet would be to optimize the power where the widest torque curve is available and in his case it down low because of slighty restrictive flow (not horible). While it would be easy to boost up the peak HP numbers on this engine to look fairly impressive it would come at the cost of overall power and low end torque. An engine that makes Gobs of low end torque that is gear right can hold it's own over the smae engine making much better numbers on a dyno. I'll give you a real life example.
My wife had a 69 Chevelle Wagon with a 454 engine. It had a set of Oval Port heads, a small Hyd flat tappet cam, performer intake and a 750 Holley Vac seconday carb. It made an unflattering 366 hp at the crank (She wanted it really mild and easy to drive with no stall,fairly smooth idle, blah blah blah) but this engine made over 500 lbs ft of torque from 1300-4500rpm. With 3:42 gears she could run mid 12's all day long in a car that tipped the scales at nearly 4000 pounds with fuel and driver. I never had it on the chassis dyno but I'm sure with the horsepower robbing Turbo 400 in it that it fell somewhere below 300 rwhp. She outran lots of "500hp"(I use that loosly) cars with a 366hp station wagon. It's all about overall power not just a peak number on a dyno. If that were the case all those 600+ hp dyno queen imports would be in the low 10 easily.
The problem is they don't have the low end torque to get the car moving and the reason so many have a hard time breaking into the 12's with such impressive dyno numbers. Just like GM's 502/502. Only 502 hp out of over 500 cubic inches with aluminum heads, hyd roller cam. Most people say "I can make that amount of power out of a 347 easy" This is true but only on the dyno hp graph. What youre missing is the 570 lbsft of torque it makes starting at 500+ from 2000 all the way to 5800 rpm. The one I had in my 68 Camaro had a super flat torque curve (so flat you can't really call it a curve) and would run 11.05's all day long shifting it at 5500 with a vac seconday carb and 3:42 gears and a built 200R4 transmission. You can impress your friends with dyno pulls with high hp numbers or you can hurt their feeling down at the local dragstrip. Doing both is good too
My wife had a 69 Chevelle Wagon with a 454 engine. It had a set of Oval Port heads, a small Hyd flat tappet cam, performer intake and a 750 Holley Vac seconday carb. It made an unflattering 366 hp at the crank (She wanted it really mild and easy to drive with no stall,fairly smooth idle, blah blah blah) but this engine made over 500 lbs ft of torque from 1300-4500rpm. With 3:42 gears she could run mid 12's all day long in a car that tipped the scales at nearly 4000 pounds with fuel and driver. I never had it on the chassis dyno but I'm sure with the horsepower robbing Turbo 400 in it that it fell somewhere below 300 rwhp. She outran lots of "500hp"(I use that loosly) cars with a 366hp station wagon. It's all about overall power not just a peak number on a dyno. If that were the case all those 600+ hp dyno queen imports would be in the low 10 easily.
The problem is they don't have the low end torque to get the car moving and the reason so many have a hard time breaking into the 12's with such impressive dyno numbers. Just like GM's 502/502. Only 502 hp out of over 500 cubic inches with aluminum heads, hyd roller cam. Most people say "I can make that amount of power out of a 347 easy" This is true but only on the dyno hp graph. What youre missing is the 570 lbsft of torque it makes starting at 500+ from 2000 all the way to 5800 rpm. The one I had in my 68 Camaro had a super flat torque curve (so flat you can't really call it a curve) and would run 11.05's all day long shifting it at 5500 with a vac seconday carb and 3:42 gears and a built 200R4 transmission. You can impress your friends with dyno pulls with high hp numbers or you can hurt their feeling down at the local dragstrip. Doing both is good too
i still cant over this poor example. omg its comical. thats less than 1hp per cubic inch. why did you just keep a stock motor in there if she wanted something easy to drive? honestly how much Torque do you need for a street car? you dont need a sh!tload of torque to burn the tires off or for it to be fun
04-02-2009, 10:09 AM
#32
1st Gear Member
Thread Starter
Join Date: Nov 2007
Posts: 74
Thanks for everyone's advice so far. I'm trying to balance what everyone has said with what my budget will allow. This is what I'm thinking.
I know (because I've done it) that I can swap heads in an afternoon. (a day if I'm taking my time) I also know that I can't afford to shell out the money for new heads right atm, even if I could get decent money for my old ones. So I'm thinking I want to build the engine anticipating upgrading the heads at some point in the future. In other words, I want to build the engine to match a set of AFR's (for example). Make sense?
So my shopping list for the time being would be:
347 stoker (what make?)
Comp Cam's Cam (the one previously recommended)
Edelbrock RPM air gap intake (power band matches the cam pretty well for a street motor I think)
Complete Gasket set
Oil pump (stock or high volume?)
All this on top of block work. *sighs* guess I should start saving.
I also have to work out the situation with my headers. I think I'm going to have to cut holes in the engine bay sheet metal to fit some shorty headers, cause the long tube headers made for Mustang II's interfere w/ my T5 tranny. No clue how I'm gonna pull that off though. :-)
I know (because I've done it) that I can swap heads in an afternoon. (a day if I'm taking my time) I also know that I can't afford to shell out the money for new heads right atm, even if I could get decent money for my old ones. So I'm thinking I want to build the engine anticipating upgrading the heads at some point in the future. In other words, I want to build the engine to match a set of AFR's (for example). Make sense?
So my shopping list for the time being would be:
347 stoker (what make?)
Comp Cam's Cam (the one previously recommended)
Edelbrock RPM air gap intake (power band matches the cam pretty well for a street motor I think)
Complete Gasket set
Oil pump (stock or high volume?)
All this on top of block work. *sighs* guess I should start saving.
I also have to work out the situation with my headers. I think I'm going to have to cut holes in the engine bay sheet metal to fit some shorty headers, cause the long tube headers made for Mustang II's interfere w/ my T5 tranny. No clue how I'm gonna pull that off though. :-)
04-02-2009, 10:57 AM
#33
5th Gear Member
Join Date: Jan 2006
Location: Puerto Rico
Posts: 3,926
Thanks for everyone's advice so far. I'm trying to balance what everyone has said with what my budget will allow. This is what I'm thinking.
I know (because I've done it) that I can swap heads in an afternoon. (a day if I'm taking my time) I also know that I can't afford to shell out the money for new heads right atm, even if I could get decent money for my old ones. So I'm thinking I want to build the engine anticipating upgrading the heads at some point in the future. In other words, I want to build the engine to match a set of AFR's (for example). Make sense?
So my shopping list for the time being would be:
347 stoker (what make?)
Comp Cam's Cam (the one previously recommended)
Edelbrock RPM air gap intake (power band matches the cam pretty well for a street motor I think)
Complete Gasket set
Oil pump (stock or high volume?)
All this on top of block work. *sighs* guess I should start saving.
I also have to work out the situation with my headers. I think I'm going to have to cut holes in the engine bay sheet metal to fit some shorty headers, cause the long tube headers made for Mustang II's interfere w/ my T5 tranny. No clue how I'm gonna pull that off though. :-)
I know (because I've done it) that I can swap heads in an afternoon. (a day if I'm taking my time) I also know that I can't afford to shell out the money for new heads right atm, even if I could get decent money for my old ones. So I'm thinking I want to build the engine anticipating upgrading the heads at some point in the future. In other words, I want to build the engine to match a set of AFR's (for example). Make sense?
So my shopping list for the time being would be:
347 stoker (what make?)
Comp Cam's Cam (the one previously recommended)
Edelbrock RPM air gap intake (power band matches the cam pretty well for a street motor I think)
Complete Gasket set
Oil pump (stock or high volume?)
All this on top of block work. *sighs* guess I should start saving.
I also have to work out the situation with my headers. I think I'm going to have to cut holes in the engine bay sheet metal to fit some shorty headers, cause the long tube headers made for Mustang II's interfere w/ my T5 tranny. No clue how I'm gonna pull that off though. :-)
04-02-2009, 11:38 AM
#34
5th Gear Member
Join Date: Nov 2008
Location: SC
Posts: 2,401
i still cant over this poor example. omg its comical. thats less than 1hp per cubic inch. why did you just keep a stock motor in there if she wanted something easy to drive? honestly how much Torque do you need for a street car? you dont need a sh!tload of torque to burn the tires off or for it to be fun
What I find comical is how you laugh at a 12 second real life grocery getter and how you put so much importance on a math figure over the action that actually moves the car. How much torque do you need in a street car? Well when you know how to drive and know how to gear around the torque the engine builds you can use as much as you want. With a Big Block The torque is pretty much a gimme. The fact that it moves the car so well is just a by product of those cubic inches. We would tow my car to the track with her car and we would run them both. Lots of Mustangs and Camaros got thier feeling hurt with her at the wheel of her wagon. To be able to run 12:40's then hook up to a car trailer and pull another Chevelle home was pretty impressive. Youre just looking at peak hp numbers. You need to pay attention to the bottom line. Mid 12 daily driver that can tow 4500lbs. Most people that laughed at her when she pulled up to stage in her big red wagon assuming it was going to be a cake walk ending up falling victim. Those that out ran her nearly alway had to run her down. Quick reaction times along with killer bottom end torque made it a tough to run down. When the person in the lane next to you gets out on you a car and a half right out of the gate you have a tendancy to make mistakes. Especially when you went expecting it. The only thing it ever got changed at the strip was a set of slicks. It was rare to hood ever got opened unless someone who fell victim to it wanted to see what got him so upset. Yeah, thats comical, I use to laugh my azz off
Last edited by Portmaster; 04-02-2009 at 11:58 AM.
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