Question: More Horsepower 1981
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Vettehead Mikey
Well-known member
Your engine is a small block Chev, not unique to Corvette. There's hundreds of books and thousands of products available to boost HP. It's easy to waste money on ineffective 'upgrades' so getting educated is essential.
How fast do you want to go, how much money have you got?
How fast do you want to go, how much money have you got?
6880 Mike
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- 1968 convertible; 1980 L-82
Tune what you have. As far as spending goes, a stock tune up is cheap. If you want modifications beyond stock, you're going to have to spend some money.
Padgett Daniel
Member
Power!!!
As a former technician, ASE Master Tech, GM Parts and Service manager I have an answer for your question. GM heads respond best to exhaust. It's the best bang for your buck period. No exceptions. By good headers, turbo mufflers, and 2 1/2 inch dual exhaust. You can swap an earlier C3 transmission crossmember to ease the installation of the duals. There's more if you truely want to know.
As a former technician, ASE Master Tech, GM Parts and Service manager I have an answer for your question. GM heads respond best to exhaust. It's the best bang for your buck period. No exceptions. By good headers, turbo mufflers, and 2 1/2 inch dual exhaust. You can swap an earlier C3 transmission crossmember to ease the installation of the duals. There's more if you truely want to know.
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bill81vette
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Daniel,Welcome to CAC!!!!
enjoy the forums!!!
enjoy the forums!!!
Peer81
Well-known member
I would say, first look at what your goal is and then look at what you need to change. If you're looking for 300hp or more then you need more then just changing parts.
Greetings Peter
Greetings Peter
Padgett Daniel
Member
Your intended usage will be the major player in the right direction for you. Street, solo, sound, drivability, or some combination. Good rule of thumb is $300 = 30 hp exhaust or 3 hp intake. Does your state allow removal of the emission equipment? If so then the answer just got a little easier. Hood clearance is a real issue with all vettes. Keep that in mind as you will have to address this issue as the hp level rises. If drvability and responsiveness is your goal, and it should be, look to packages from Edelbrock, Holly, etc. The best improvement will come with a change from a complicated 4EME carb to a throttlebody EFI. They arr much simpler with most coming with an ultra simple handheld contol unit that is self learning. Milage, smooth idle, instant response, and ease of tuning are all there. Avoid agressive cams. They are the absolute last item that should be changed because stock heads, exhaust, and intakes will neuter it. Don't waist your money on ignition. A simple refresh will be fine. All stock electronic ignition systems will be more than enough until you install a power adder like NO2, blower, or turbo as they increase the air density which requires more energy to cross the plug gap. Regular engine only mods only use the pumping forces already present with improved efficency. What to know more?
Padgett Daniel
Member
Thanks! Glad to be here.
I'm looking for more Horsepower for my 1981, over the last 3 years I've lost the "mojo" to drive it...Over the Christmas holidays I've been doing a bunch of research. Its looking like a Chev crate engine, the 350 HO Turn-Key p/n 1921009, its 330 HP @ 5000 RPM and 380 ft-lbs @ 3800 RPM. Its also available in 2 other part numbers, 350 HO Deluxe p/n 19210008 (intake, carburetor and distributor not installed) and 350 HP Base p/n 19210007 (without intake, carburetor and distributor). The Turn-Key engine comes with a carburetor, however I would like EFI, looking at Edelbrock E-Street or equivalent in place of a carburetor. Trying to justify the EFI, cause it adds around $2000 to $2600; for that price, I'm still looking at options... thought I share..
Padgett Daniel
Member
Drivabilty, response, fuel economy, no adjustments for humidity, BARO, altitude, temperature, etc. Carbs are WAY more complicated than any EFI system. Spent years as a carb man on a winning drag team. Be smart and sure that it'll start (heat soak) and go EFI. Used the HO one one of my projects once. Fine engine with plenty of real world power that you can use. Holley required constant adjustments for NC's ever changing weather. Edelbrock builds the best street carb. Period. Fuel econ. suffers because of lack of adjustability like a Holly, but for anyone other than a Master Tech. that's a GREAT thing. Remember it torque and tractability that you want and not wheel spin. Drag race teams speed several thousand dollars and hundreds of man hours eliminating it. If I remember correctly the HO comes with a cast crank, PM rods, and cast pistons. Pefect. All any none power adder engine ever needs. Don't waist money on forged unless you are north of 500hp. Then your car becomes a race only vehicle. Don't get me started on the new vehicle hp war. It'll be the death of performamce vehicles just like '74. Sorry. Great engine choice.
Padgett Daniel
Member
Size
EFI or carb. size matters. Carb. much more so. Performance carb. 650 (Holly), 670 (Edelbrock), and 700 ish for EFI as it self learns. Still EFI can't overcome poorly mismatched components and too big is still too big. Agressive cams are always deal breakers. Call the manufacturers for assistance. Please, don't say you want a lopy idle when they ask what you are looking for in a cam. We put 2,000+ hp out of a pro drag car and it idle smooth as butter because we worked with the cam company to speck it for max power with our suspension, vehicle weight, tire size, diff. gear, RPM range, length of track (yes track length), transmission gearing, and engine comp. including the flow of the heads, intake, and fuel system type/size. All of this and more. Why buy a rough idle cam after spending all of that money balancing the rotating parts, a high quality balancer and flexplate/flywheel? Rough idle means the cam timing is off PERIOD! Don't be fooled by hype. It means excessive overlap which is a very bad thing for power. It contaminates the intake charge PERIOD! If you want sound by a better stereo. Keep the mufflers quite or you'll regret it. Keep the exhaust size limited to 2 1/2 inches until north of 500+ again. Spend money on those 0 gauge ground straps and uretane mounts which will guarantee response. The ground straps will net you 10 hp in every application I've tested them on. Another case of factory cost cutting. If you go hotter than the HO you'll need larger fuel supply lines to feed the beast. I say this because I too have felt the itch. Remember my background. Please, make yourself a pledge to build it one time only. Don't cut corners just do it as you can afford it or have the time. It'll cost you 5-10 times as much if you settle, because you will always ask 'what if'. As always ask and I will reply as my work schedule allows.
EFI or carb. size matters. Carb. much more so. Performance carb. 650 (Holly), 670 (Edelbrock), and 700 ish for EFI as it self learns. Still EFI can't overcome poorly mismatched components and too big is still too big. Agressive cams are always deal breakers. Call the manufacturers for assistance. Please, don't say you want a lopy idle when they ask what you are looking for in a cam. We put 2,000+ hp out of a pro drag car and it idle smooth as butter because we worked with the cam company to speck it for max power with our suspension, vehicle weight, tire size, diff. gear, RPM range, length of track (yes track length), transmission gearing, and engine comp. including the flow of the heads, intake, and fuel system type/size. All of this and more. Why buy a rough idle cam after spending all of that money balancing the rotating parts, a high quality balancer and flexplate/flywheel? Rough idle means the cam timing is off PERIOD! Don't be fooled by hype. It means excessive overlap which is a very bad thing for power. It contaminates the intake charge PERIOD! If you want sound by a better stereo. Keep the mufflers quite or you'll regret it. Keep the exhaust size limited to 2 1/2 inches until north of 500+ again. Spend money on those 0 gauge ground straps and uretane mounts which will guarantee response. The ground straps will net you 10 hp in every application I've tested them on. Another case of factory cost cutting. If you go hotter than the HO you'll need larger fuel supply lines to feed the beast. I say this because I too have felt the itch. Remember my background. Please, make yourself a pledge to build it one time only. Don't cut corners just do it as you can afford it or have the time. It'll cost you 5-10 times as much if you settle, because you will always ask 'what if'. As always ask and I will reply as my work schedule allows.
Last edited:
Padgett Daniel
Member
Better idea!
Does you '81 still have the old TH350? Call Art Carr and get a TH200 4R. You can use the same trans. mount, cross member location, and driveshaft as the TH350. The 200 can shift into OD at wide open throttle (WOT) which the TH700 R4 never will. Art says the 200 can handle twice the power of even the best 700, offers greater fuel economy at high speed (see above), and closer gear ratios than the 700 with a better first to second to prevent the dreaded first wheel spin and then baby fart flat shift to second that plagues all 700s. Get it in any level you want. Mid America offers a bolt in OD shift conversion on the cheap. That, the HO, and EFI will make yours the best real world street C3 and the envy of every knowledgable owner that sees it or is lucky enough to ride in it. Same system approach that all of the smart people offer in their catalogs like Edelbrock, Dart, World Products, Trick Flow, GM, etc. This is THE formula for success. Look at ANY new car or truck. Eight forward speeds, direct injection (no way you could convert any engine), and grunt down low equals fun and economy. Enjoy.
Does you '81 still have the old TH350? Call Art Carr and get a TH200 4R. You can use the same trans. mount, cross member location, and driveshaft as the TH350. The 200 can shift into OD at wide open throttle (WOT) which the TH700 R4 never will. Art says the 200 can handle twice the power of even the best 700, offers greater fuel economy at high speed (see above), and closer gear ratios than the 700 with a better first to second to prevent the dreaded first wheel spin and then baby fart flat shift to second that plagues all 700s. Get it in any level you want. Mid America offers a bolt in OD shift conversion on the cheap. That, the HO, and EFI will make yours the best real world street C3 and the envy of every knowledgable owner that sees it or is lucky enough to ride in it. Same system approach that all of the smart people offer in their catalogs like Edelbrock, Dart, World Products, Trick Flow, GM, etc. This is THE formula for success. Look at ANY new car or truck. Eight forward speeds, direct injection (no way you could convert any engine), and grunt down low equals fun and economy. Enjoy.
Padgett Daniel
Member
Transmissiom
Find a TH200 4R from any OD G body like Cutlass, Monte, Regal, Gran Prix, El Camino or many B bodies like Caprice, etc. Buy a master rebuild kit from B & M (red Alto clutches and Koleen steels), a Beast sun/reaction shell, TCI clutch apply piston assemblies, an B & M Super Cooler (only cooler that can take rocks head on anywhere), Deral transmission pan with cooling tubes, a locking dipstick from Locar, Summit Racing 2700 RPM torque converter, and a case of expensive full synthetic ATF. Take it to your trusted trans. shop for rebuild selecting the auto/manual valve body mod. option as the kit offers a manual only that you'll hate after the first day through town. It'll destroy your diff. and shake your car to bits too. More info.?
Find a TH200 4R from any OD G body like Cutlass, Monte, Regal, Gran Prix, El Camino or many B bodies like Caprice, etc. Buy a master rebuild kit from B & M (red Alto clutches and Koleen steels), a Beast sun/reaction shell, TCI clutch apply piston assemblies, an B & M Super Cooler (only cooler that can take rocks head on anywhere), Deral transmission pan with cooling tubes, a locking dipstick from Locar, Summit Racing 2700 RPM torque converter, and a case of expensive full synthetic ATF. Take it to your trusted trans. shop for rebuild selecting the auto/manual valve body mod. option as the kit offers a manual only that you'll hate after the first day through town. It'll destroy your diff. and shake your car to bits too. More info.?
Padgett Daniel
Member
If all else fails!
My budy and I just finished a '69 conv. tri power, 4 speed, red w/blk. top and interior for our collector friend. It had a cat inside when the rollback dropped it off from Ohio. The previous owner spent $30 on brass fittings and rubber hose we replaced with perfect hard lines. Carbs. sent off for complete resto., and no expense spared on the mechanicals. Concours quality truely. Previous owner replaced the interior and top plus one stuned cat. He has three large commercial buildings full of vehicles that never get driven until we are asked to update the new Autometers with New Stuart Warners like the first ones we put in his 6.1 Hemi 41 Dodge business coupe. Ask your wife about a second mortage first. Dream big. Tist the season. Miles of smiles to everyone that reads this.
My budy and I just finished a '69 conv. tri power, 4 speed, red w/blk. top and interior for our collector friend. It had a cat inside when the rollback dropped it off from Ohio. The previous owner spent $30 on brass fittings and rubber hose we replaced with perfect hard lines. Carbs. sent off for complete resto., and no expense spared on the mechanicals. Concours quality truely. Previous owner replaced the interior and top plus one stuned cat. He has three large commercial buildings full of vehicles that never get driven until we are asked to update the new Autometers with New Stuart Warners like the first ones we put in his 6.1 Hemi 41 Dodge business coupe. Ask your wife about a second mortage first. Dream big. Tist the season. Miles of smiles to everyone that reads this.
I still have the original TH350...I was picking the engine to match the TH350. And yes, this will be a one time build as I have another project vehicle after this. If I'm going to change the transmission, then I'm needing to take a step back on the 350 HO Turn-Key (330 HP @ 5000 RPM and 380 ft-lbs @ 3800 RPM) engine, perhaps the ZZ4 350 Turn-Key, its 355 HP @ 5400 RPM and 405 ft-lbs @ 3600 RPM or the Ram Jet 350, 350 HP @ 5200 and 400 ft-lbs @ 3500 RPM, the RAM Jet will solve my EFI wish...Ram Jet should be ok with the 2-bolt main. Anybody swap these engines into '78 - '82 Corvettes? So many good choices...
Peer81
Well-known member
Hood clearance is your main concern with turn key engines. Maybe a ramjet will fit but overhere I don't see them with a stock c3 hood.
Greetings Peter
Greetings Peter
MarkH
Member
Your engine is a big pump, so add power by increasing intake and exhaust. some examples:
Aluminum intake manifold
Camshaft to increase midrange torque at 2200 to 5700 rpm. Include lifers and rollers
improved balancer
100A alternator
2 1/2" or 3" headers (biggest gain) with magnaflows
MSD or AEI distributer and ignition
aluminum radiator to handle the extra power. include a flex-o-lite fan to reduce drag on the engine
leave your quadrajet carb alone. it would take a lot to improve on it.
expect to pay $2-3k on all of this.
Aluminum intake manifold
Camshaft to increase midrange torque at 2200 to 5700 rpm. Include lifers and rollers
improved balancer
100A alternator
2 1/2" or 3" headers (biggest gain) with magnaflows
MSD or AEI distributer and ignition
aluminum radiator to handle the extra power. include a flex-o-lite fan to reduce drag on the engine
leave your quadrajet carb alone. it would take a lot to improve on it.
expect to pay $2-3k on all of this.
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