Getting HP
Thread Starter
Heel & Toe
Joined: Nov 2004
Posts: 22
Likes: 0
Getting HP
Ok, well im new here, and i dont know if im breaking any rules, but i need horsepower. I have, i mean we have, ok my dad has a 75 corvette stingray with the lower compression 350. My dad decided he would finally allow a rebuild for more power, we have decided that 375 at the wheels is a good number. Now i dont know much about the car, because he never lets me touch it, so i dont know about the rear end gearing.... Its got the 4 sp, and its bone stock. So yea, im guessing around 415 to 430 at the wheels, so what would you recomend. Im thinking punching it 30, shaving 30 off the heads, and zeroing the block, then a bigger carb, eddlebrock intake,and loppy cam, headers and an extremely free flowing exhaust. If thats not enough, i would get some high compression heads, and if i still need more id stroker the motor, if thats not enough, well dammit, what is... LOL... So yea, if anyone has a 350 with the lower compression (i think its 8.8) heads, and gotten close to 400 HP, please post with mod information and estimated cost.
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
It all depends on what you're willing to spend. Your looking at a 450 horse motor at the flywheel. A small block can be built to produce those numbers, but it's on the edge of streetability for a 350. Heads should be budgeted first, as they will determine the rest of the motor (Alum heads allows higher c/r & more cam) 383's and so on can get expensive, a stock no-frills big block may be a better choice.
Remember that the little stuff can kill the budget quick.
Remember that the little stuff can kill the budget quick.
Instructor
Joined: Sep 2004
Posts: 168
Likes: 0
From: Houston Texas
Getting over 400 HP at the wheels out a 350 is going to be tough. It will be impossible without some very good heads. You can generally get about 1.1 to 1.2 HP per cubic inch in a naturally aspirated streetable 350 at the flywheel. Some will say more but it all depends on your definition of streetable. We are talking dyno HP here. Knock off about 40 HP for the accessories and then another 20% for drive train losses and you have to start with quite a bit of dyno HP to get 400 at the rear wheels. By my rough calculations you would need about 540 dyno HP to get 400 at the wheels. It's going to take some really good heads like ARF's (Air Flow Research) at about $1,300 a pair at your door. A really big cam cause your going to have to spin it to the moon, some long tube headers with 1 3/4" primaries etc.
You probably didn't want to hear all of this but there is that old saying "going fast cost money, how much do you want to spend?"
You probably didn't want to hear all of this but there is that old saying "going fast cost money, how much do you want to spend?"
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
The other replies have been somewhat sugar coated and I respect them for that. To get 375hp at the wheels you are not looking at a rebiuld, you are looking at a complete engine. The only thing that may be reusable is the block. I would either lower the horsepower requirement or switch to a 502 or 572 big block. The big block should be more streetable due to the simple fact that it does not need to be as exotic to knock out the same horspower as the small block. Unless you're planning on racing (at a track), 400 to 450hp at the flywheel should be plenty for a street driven car. My 76 which is rated at 180hp has no problem hitting the legal peed limit of 65, and does it with ease.
Thread Starter
Heel & Toe
Joined: Nov 2004
Posts: 22
Likes: 0
AHAH well i knew that getting 375 at the wheels would require a basically a new block, just build off the old block and nothing else remaining. The number is out of my dad of all people, (he drives a land rover disco 2 like an old granny and he admits it) why i dont know, but i would never argue with horsepower. So the question still remains, with all that is listed, can i get it to 375 at the wheels without getting high compression heads if i do some extensive work on the heads and without strokering it.
Drifting
Joined: Jan 2002
Posts: 1,500
Likes: 0
From: N.Y
On a chassis Dyno I made 388 at the rear wheels running on the rich side so 400 at the wheels is just a couple of jet sizes away. What I have is a 383 Eagle steel crank, H Beam rods, je forged floating pistons, Moroso pan,, Trick flow heads, ported by one of the beast engine shops around a hydraulic roller cam, at 050 the cam specs are 236,246 520,540 Edelbrock air gap intake, a totally tricked out 750, msd ignition 370 gears, All the assembly as always was done by me so the facts are right on. So far ran the best of a 12.24 This is running rich and with a stock tork converter. So this should be a 11.70 car when the bugs are out. I drive it every day. It is very choppy at a idle and makes just enough vacuum at idle so everything works. I gave you a detailed set up so you can get a good idea on what you need. How fast do you want to go? You can buy a nice GM crate motor and drop it in on the weekend. Probably run low 13.00 or high 12.00 quarter mile passes.
Race Director
Joined: Apr 2000
Posts: 17,650
Likes: 190
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
As stated above you need the best heads money can buy. THe heads need to flow about 275cfm at .600" lift and there aren't many out there out of the box so you will have to port any heads you get. 11:1 CR. a cam in the 260-270 duration range with .600 lift, unless it's a solid roller and yo might be able to get the duration down to point you can drive it on the street. A good rotating assembly because you will need to spin ot to 6500 RPM At least a 750 double pumper carb, single plane intake, good headers with free flowing exhaust and free flowing muffler ( read loud). A loflty goal you have set for yourself but that is OK. It is possible to make that kind of HP out of a 350ci the real problem is making it driveable on the street. I would be shooting for 300 RWHP and without aftermarket heads you will not see 300RWHP, I would think about a 406ci or bigger for that kind of HP
Thread Starter
Heel & Toe
Joined: Nov 2004
Posts: 22
Likes: 0
hmmm, so could i get away with lots of headword on current heads rather than forking over over 1000$ and still having to do more work on them? Does anyone have an estimate for how much power i am looking at with high flowing carb, eddlebrock intake manifold(performer RPM), a good loppy cam(still streetable), zero the block, zero the heads, punched 30 over, headers and high flow cat, no muffler, duals out the back, and lots of headwork... im thinking about 300 to 325? What else would be required to hit 300 to 325 at the wheels?
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Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
Originally Posted by Twilight Child
hmmm, so could i get away with lots of headword on current heads rather than forking over over 1000$ and still having to do more work on them?
Le Mans Master
Joined: Oct 2004
Posts: 5,269
Likes: 54
From: Orlando Florida
St. Jude Donor '05
You agreed to 375HP at the wheel being a good number. I agree, that is a very good number but it's difficult to achieve and very expensive.
With 64cc heads (Edelbrock $1000), cam and lifter kit, pushrods (Comp Cam $400), roller rockers ($150), intake (Edelbrock $150) and forged crank and pistons (roughly $1000, maybe Jegs) and finally a carb (Holley $300) you are already looking at $3000 in parts plus small stuff and gaskets....
I would think this will produce about 350HP at the wheels with 10.5 CR... and will be very streetable power, not only top end...
With 64cc heads (Edelbrock $1000), cam and lifter kit, pushrods (Comp Cam $400), roller rockers ($150), intake (Edelbrock $150) and forged crank and pistons (roughly $1000, maybe Jegs) and finally a carb (Holley $300) you are already looking at $3000 in parts plus small stuff and gaskets....
I would think this will produce about 350HP at the wheels with 10.5 CR... and will be very streetable power, not only top end...
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Originally Posted by mandm1200
The other replies have been somewhat sugar coated..
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Originally Posted by Twilight Child
.... can i get it to 375 at the wheels without getting high compression heads if i do some extensive work on the heads and without strokering it.
I built my 355 around the heads. IMO, you need good aluminum heads - Dart, AFR, Brodix, etc. You will toss you time and money away having stock heads reworked. My 355 does not have the low end like the 383 had, but it really makes power when you wind it up a little more, and sounds way better than my 383 ever did. I can't wait to add a bigger cam and compression to this little motor.
Last edited by 71coupe; Nov 28, 2004 at 10:21 PM.
Melting Slicks
Joined: Jan 2004
Posts: 2,672
Likes: 1
From: New Cumberland PA
I believe that you a grasp on what would be needed, but the posts made before mine essentially mentioned heads. In a low compression engine made in 75, it going to require a lot more than that in my opinion. Perhaps I misread things and you were saying to pick out a good set of heads and then change everything else to match up to them.
Melting Slicks
Joined: Jun 2001
Posts: 2,429
Likes: 14
From: CA
Good heads can really make a difference. Aluminum heads will allow a higher crompession without pinging, more than 1 full point over iron. Once the compression is higher, you can have more cam duration. Most people make the mistake of putting a big cam in a low 9.0 c/r motor. It doesn't work - too much pressure bleeds off during the cam events.
The trick is to build it so it still works on pump gas in your area. I can get Sunoco 94 where I live. My 10:1 runs good on 89. I wonder how much I can raise my compression? Hmm.
The trick is to build it so it still works on pump gas in your area. I can get Sunoco 94 where I live. My 10:1 runs good on 89. I wonder how much I can raise my compression? Hmm.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
375hp at the wheels with a 350ci engine... Makes me drool but I'd say drivability will be 'rough'. See my numbers. This is a very streetable car with significant rwhp/rwtq improvements AND it roasts the tires and gets rubber between 1-2.
Allowing for 22% driveline losses, I'm seeing 285hp/370tq at the flywheel. If folks are more foregiving and allow for 30% driveline losses, the numbers are more like 318hp/412tq.
Allowing for 22% driveline losses, I'm seeing 285hp/370tq at the flywheel. If folks are more foregiving and allow for 30% driveline losses, the numbers are more like 318hp/412tq.
Last edited by TedH; Nov 28, 2004 at 04:05 PM.
Thread Starter
Heel & Toe
Joined: Nov 2004
Posts: 22
Likes: 0
Hmmm, sounds like im on the right track at least. My main performance knowledge is on a ford 300-6, torque moster as i would have it called, but it, like anything else is an engine, i have found a few high performance rebuild kits which includes just about everything short of 10 HP stickers, are there any kits available for my type engine? Such as kits that include the everything minus like the heads and carb?
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Originally Posted by Twilight Child
Hmmm, sounds like im on the right track at least. My main performance knowledge is on a ford 300-6, torque moster as i would have it called, but it, like anything else is an engine, i have found a few high performance rebuild kits which includes just about everything short of 10 HP stickers, are there any kits available for my type engine? Such as kits that include the everything minus like the heads and carb?
http://www.northernautoparts.com/Pro...ctModelId=1668
Thread Starter
Heel & Toe
Joined: Nov 2004
Posts: 22
Likes: 0
AHHAH UNFAIR, it would cost me 370 $ + shipping just for cam, lifters, pushrods, rockers, and valve springs, grrr on my unique engine, all though haveing a 300-6 screaming 6500 RPMS would be hella tight.