How much much Horsepower should my Kit Car Have?
First Question : How much HP is enough and How much is Too much ?
300 – 400 – 500 + HP ? What is right for you ?
This comes down to driving Style. Broken down into different categories.
Stage 1 : Daily driver, Smooth Idle, Factory to slightly Modified Engine. 230–275 HP Range
Stage 2 : Cruiser, More Aggressive Idle, More added Punch & Torque 275-350 HP Range
Stage 3: More Lopy, Racier sounding idle, Increased Low to Midrange HP and Torque, Striking a balance between streetability and Power. We deal with most guys who fall into this category. Anywhere from 350 to 475 HP Range.
Stage 4 : Choppy Idle, Street / Strip use, Big Camshaft and High Compression. A Headturner. Highly Modified Engine. This would be more around the 500+ HP Range.
Some Important Points to Keep in Mind
Many of these cars are very lightweight. Around 2000 lbs. overall. So they will be very responsive to Even mild enhancements. to give them a launching effect.
Idle Quality When you have a big camshaft in an engine it may sound cool to have a big choppy idle. But it can actually cause more harm than good. The bigger is better philosophy can cause headaches. The engine has less Vacuum to Idle properly, Less Streetable to drive, More tweaking and tuning to maintain.
You can actually lose power in many cases. The important thing is to find a happy medium to stay within the Power band you are driving in most. A lot can be achieved from an engine without going with a Huge camshaft or Carburetor.
Type of Fuel Big Compression Engines have no place for running on the street. To run pump gas in your engine it’s wise to keep compression within 9 to at the most 10.5 to 1 Ratio. Compression beyond this can cause the engine to start running Hotter and cause preignition or worse detonation problems.
Radiators and Oil Coolers Engines need to run cool to perform at their best. Even the best Water pump in the world is not going to make up for a restricted or defective Radiator. The bigger and more potent the engine the More important it is to have an efficient Cooling system. The Radiator is something not to Skimp on. Oil Coolers are popular setup for some of the big Block engines it can be helpful otherwise the smaller engines can do fine without them.
Domino Affect Whenever you start climbing up in Horsepower / Torque keep in mind that the rest of the car needs be setup to handle this. The Rear End, Transmission, Clutch, Suspension, Braking, Cooling System. Etc. Everything needs to work in Harmony. Otherwise the weakest link can be exposed and break.
Small Block V-8 Chevy engines deliver the most bang for the buck. Light weight , Plentiful and most of the manufacturers setup their cars to easily drop them into place. Plus you can get all the power you need out of them.
The 350 is a nice motor to start with. With a steel Roller Cam in it. You can wind it up quickly and is very quick from 0 to 60 MPH. The stock engine with about 230 HP is excellent for a daily driver and the Factory Transmission and Gearing.
It can be built up extensively more HP with a Hotter Cam, Aluminum Heads, and a efficient Flowing Induction System. Obtaining 350 HP is a good goal to obtain without sacrificing reliability. When you want to get more out of the 350 Chevy, stroking it out to a 383 would be the best way to go when going beyond the 400 + HP Mark. Those of you who may not be familiar with a stroker engine, the outside of the engine is the same as the 350 Chevy. Internally the Crankshaft index has been changed giving it more cubic inches. For Example the stock 350 Chevy stroke is 3.480 inches. With a stroker crankshaft, the stroke is now 3.750 inches. After boring the block.030 oversized this changes the cubic inches from 350 to 383 cubic inches. With Forged components like the connecting Rods and Pistons and a Cast Steel Crankshaft it’s a proven performer ! A lot of people feel that a Cast crankshaft can’t handle higher strains. The Eagle Cast/Steel Crankshafts are Designed to handle up to 500 HP. Same goes for connecting Rods. H Beam Connecting Rods are nice insurance but when using the Factory Rods with some ARP Retaining bolts they hold really strong.
383 Stroker Engine
This is our best selling Chevy Engine. Lots of advantages with using this motor.
1. Same Engine Mount and Transmission Bellhousing pattern as the 350 Chevy.
2. It is the same weight as the 350 Chevy
3. The 383 Stroker is a great engine to give you the seat of the pants Grunt power more so than the 350 Chevy. This motor can develop huge torque similar to the Big Block Engines.
Not unusual for these to go from 0 to 60 in 3.9 seconds. The 350s are capable of doing it in about 4.5 seconds. These engines can easily get 450+ HP and develop 460lbs of Torque. The car can really launch with this setup. Again matching it up with the right Transmission and Clutch among other upgrades is a must.
502 Big Block Engines
This engine is rarely seen in the Cobra Replicas or other Kit Cars. Due to the weight increase of about 250 lbs. more than a Small Block Engine it can compromise the handling of the car. The Kit company would need to be notified if you intend on putting in a 502 Big block thats being fitted to go into Rolling Chassis of the car. So the proper mounts are supplied and hood clearance is checked to prevent any problems
Performance Gains Basics
Here are some basics on gaining power.
Fuel Delivery system.
Don’t need a lot of Carburetor when you have a smaller engine in the car. As the efficiency and horsepower of the engine increases or you have a big block engine, then a bigger carburetor would be beneficial.
The 350 chevys up to 430 horsepower can handle a 650 cfm carburator. The more efficient the engine is the more Air and Fuel can be pumped into it and therefore a bigger Carb. The Chevy 383 stroker 450 plus horsepower and big block engines require an 800 cfm carburetor.
Edelbrock Intake Manifolds
Dual Plane for low to mid range speed. Power Range from 1500 to 6500 RPMs.
Single plane design more for mid to top end Power. 2500 to 6500 RPMs
If you were going to pick one bolt on item that would get you the most power .. Cylinder Heads would be it. With the time and money invested in Porting and Polishing Cast Iron Heads you can buy better flowing and lighter Aluminum Cylinder Heads with much larger Intake and Exhaust Runners and bigger Valves. Using the proper Matching Camshaft can easily add 100 HP.
Factory internal parts will be fine for slightly modified engines. Once HP figures start climbing up then more attention needs to go to beefing it up the bottom end.