Opinion: What Everyone Should Know

I have another "essay" I thought about,wrote,and am sending to you: It is about understanding the choices about picking the right parts to give third generation f-bodies more power.I will also explain how different motor items such as cams,heads,intakes,exhaust systems and headers,bottom end,trans and gear choices,supercharging,and nitrous.Most of the info is based in fact,however my opinion is evident in a few areas.

Combination is all important:the sum of the parts is greater than the whole. In producing max power,a motor that has all areas closely matched into an effective combo will always outperform a mix and match motor.The reason is that all parts have to complement each other in order to make max torque and hp.A good example is a stock 350 TPI motor out of a camaro/firebird,it makes good low end torque,excellent midrange,and good top end power with good fuel mileage.You may say that it is not so beacause adding aftermarket parts such as exhausts and chips make more power-that is not the idea.All of the parts work within the same rpm range;the head ports and valves are small,the cam is weak,and the design of the long runner TPI system maximizes torque-a good combo for which it was intended.Others look in magazines and see Lingenfelter 383 cars running low 12’s,wondering if they can do better with a mismatched 350;sorry to burst your bubble,but most every 350 or 302(ford) street motor barely pushes 300hp,put it into a 2500lb RX7 and it will run 12’s,don’t think a 3400lb camaro or firebird will.The reason why the 383 makes so much power is that the motor is 10% bigger than a 350(or 10% more hp),and the fact that it makes peak power at 5500rpm,instead of 4500rpm like a stock TPI does(22% more power).If a stock 350 makes 250hp,and multiply it times 10% and again by 22%,you get only only 335hp,those 383 make 430hp.How?by making the motor more efficient,you make more torque(and therefore hp) at all rpm.The stock TPI motor is about 80% efficient on its best day,the 383 pushes 95%-which is the 95hp difference.I don’t expect too many novices to understand efficiency,but the following areas I’ll cover will help you get the ideas.

Heads:

Heads are the main bottleneck in the motor,putting mega heads on a stock motor will not make power;closely matching the heads with your cam will make max power.Why do I say this:there are a million different cam profiles,and a hundred head designs ported by a thousand porting people.You need to know exactly where you want the power(rpm wise),before you buy heads(and cam).Larger cc runners are meant for either(or) high revving or large ci motors,larger valves(2.05 intake and larger) work the same.Typical runner volumes on stock 350’s run 155cc,and work well up to 5000rpm.The CNC ported L98 heads that my camaro has are about 180cc,and work well up to 6000rpm.Dart Sportsman 2’s are 200cc,and are intended to run up to 7000rpm…etc.You may think that the Darts are best,but they sacrifice air velocity at low rpm’s for top end hp.The loss of velocity constitutes a major loss of torque,requiring high rpm torque converters and big gears. When you look for a head for any chevy(or v-8 domestic motor),ask questions about all of your choices,then act,otherwise you may buy the wrong heads.

Cams:

Cams should be closely matched to the heads because the combo has to be matched closely. Cams have two major functions:duration and lift,I’ll explain them both: Duration is directly responsible for what rpm the power peak falls at,there is a decent,but simple way of figuring out where that peak will occur.You look at the 0.050" duration (degrees),a good rule of thumb is(with a 350ci motor),220deg will peak at 5500rpm,210deg at 5000rpm,200 at 4500rpm(stock 350 cams),230deg at 6000rpm…etc.As you can see the addition or subtraction of 10deg moves the power up or down 500rpm.Heads must be closely matched to make the peak at the rpms(otherwise the heads are a bottleneck),also long runner intakes like a stock TPI limit hp above 5000.Putting a 230deg cam into a motor with a stock TPI will make peak power lower than 6000,so don’t do it. Lift is more important than duration(in my opinion) because lift has a direct effect on torque at a given rpm.If the heads you are using can flow better using a higher lift,use it to maximize torque at all rpm points(1.6 rockers also increase valve lift).Regular hydraulic cams(non roller) have lift problems,design only allows so much lift with a certain duration.Roller cams(standard from 1987-1997) do not have a limit on lift,making them worthwhile investments.I’ll give you an example:a friend has a camaro with an older 350(non roller),he has a cam with 235deg at 0.050 and .501 lift(the limit),heads with the same cc(180) as my CNC L98 heads,same intake and exhaust systems.His motor makes peak power at 5500rpm(bottleneck is the heads,the cam is good for 6200 peak)and puts out enough hp (300) to run 103mph in the quarter,certainly respectable.My car has a Accel roller with 219deg at 0.050 and .560 lift (with 1.6 rockers),coupled with the CNC heads and same intake,exhaust..etc,it makes peak power at 5500rpm(projected peak).The car has enough hp to run 108mph in the quarter (355),despite weighing 200lb more.My combo was better matched and made more power than his,my car also idles better and gets better mileage also.Use 1.6 ratio rockers to pump up lift,regardless of which cam type you use.Also make sure your valve springs won’t bottom out,use premium quality head gaskets,use ARP or other head bolts(or studs).The stock motor will tolerate .600 lift cams before valves hit the pistons (350 motors).

Intake:

Intake should be selected after the cam and head combo is made,as there are only four different TPI intake designs,and maybe 12 carb intakes,it leaves less chances to make a mistake selecting an intake manifold! There are four different TPI intake designs:GM stock style(long runners),Accel superram,TPIS miniram,and SLP’s intake(inferior due to inability to port,I ignore it). Luckily,each one has a different function and operational rpm range so you cannot confuse them easily.The stock TPI intake has long runners(about 22" long),coupled with a medium displacement plenum(I’ll explain plenums later),long runners are a restriction to high rpm use,but make the best bottom end torque.Motors using stock(or ported) TPI style systems will barely make peak power over 5000rpm(even in a 305),soley because of the intake.The Accel SuperRam has shorter runners(about 16") and a larger displacement plenum,breathing better at higher rpm because of shorter runners.Shorter runners take some low end torque away,the larger plenum is used because it acts as a "reservior or capacitor" to bring back the longer system’s torque(it does it well).The SuperRam will push peak power to a max of 6000rpm,an increase of about 1000rpms.The TPIS miniram was the model that GM used in designing the LT1 intake(they look similar?),and makes max top end hp with the expense of low end torque.The miniram has very short runners(about 5"!) and a small displacement plenum,couple those two items together and it pulls to 7000+rpm.To show you how much it kills the bottom end,driving a LT1 is like driving a 4 cylinder turbo compared to an L98.The LT1 uses a cam with the same exact duration as the L98,but has to use greater lift .450/.450 vs .415/.430 than the L98 and is still shy on torque.This intake is meant for large displacement (406+ inch motor) that have too much torque(burn tires for blocks) to trade top end for bottom end torque.A 383 could probably handle a miniram,but a 350 would be too sluggish down low.Since most f-bodies that people buy for speed are TPI,I won’t talk about carb intakes.

Engine Displacement:

There is no substitute for cubic inches is a popular addage,it is true;a large motor will produce more power at the same rpm than a smaller motor will.For example,my 350 makes 350hp at 5500 rpm;by that rule a 305 should make 305hp and a 420 should make 420hp at the same 5500rpm if the efficiencies were the same.However,the efficiencies are not,the 305 and 350 run about 90% at 5500rpm;the 420 will be 95% efficient.Why? because the 420 is built(stroke,rod length,bore size) to make the most power in a small block as possible.It makes 470hp at 5500rpm,or about 1.11hp per cubic inch.This may not make sense,but since the motor is optimized in all ways,power adds up to be greater than the sum.Mostly the longer stroke (3.875" vs 3.48") and the larger bore (4.155" vs 4.00") make more torque(stroke) and better high rpm power(valves unshrouded by larger bore). In short:build the largest motor(cubic inches) you can afford.

Bottom End:short block

Most people think that forged pistons,for bolt main caps, and steel cranks will make a motor faster;they only make it stronger(these people never need it though).Dump those ideas now,otherwise you will spend money foolishly. Pistons regulate compression and take all of the force of combustion in the motor,stock pistons are good to 500 or more hp if the motor is setup correctly,after that use forged pistons.TRW forged pistons are not even in the ballpark in strength as Ross,Wiseco,and J&E.The reason is that they are made too heavy(unneccessarily) and are made of weaker metal.Spending the money on the better names is well worth it if you need it,otherwise use stock type pistons(and save $). Rods take the abuse passed through the piston and apply it against the crankshaft,they are hit with stress from 2 ends and need to be strong.The stock rods are strong enough for 500+hp,above that use 4340 steel rods from reputable companies such as Oliver,Manley,Childs and Albert…etc.Pink rods are shit compared to 4340 rods and cost the same,skip pink rods(unless they are free). Crankshafts are the device that turns up and down motion to clockwise(or counterclockwise motion) in the motor.Cranks need to be:precisely balanced with pistons and rods;and also need to be kept under the rpm in which they break.Stock cranks should not be revved over 6000rpm because the rods and pistons put tremendous stress on the crank and can destroy it.A motor that needs to be revved above 6000rpm,or is in a large cubic inch motor should be a step or two up from a stock crank.A "steel" crank or equivalent is a step up in strength and cost,as are the other levels up to the ultimate 4340 billet crank(used in top fuel motor).If you need to look for a crank,look at Callies,Crower,and Cola;they all make cranks for any motor,budget,and power range. Four vs two bolt mains:Two bolt mains are good if you don’t rev the motor over 6000 and don’t have a heavy duty turbo or supercharger on the motor.Otherwise (even with nitrous) a two bolt is adequate for almost any street cars.It is really a nonissue,since your street car won’t ever need it.

Superchargers:

First,they have their pros:more power at most rpms,can make a small block have big block torque and hp,and look cool.Cons:are expensive,they add 50+ lbs to the car,they are not "sneaky" as they are easily visible,some require fuel system upgrades,and once you put a supercharger on top of a motor with major internal work the stock computer can’t handle it and DFI is needed.They make precision motortuning 10 times harder. The best kits are either Intercooled superchargers (ATI),or intercooled turbos (turbo technology) because there is no excess heat generated as in the paxton and vortech superchargers.I have quite a few friends with them,most feel that it is worth it because their motor was not ripped apart,otherwise they lean toward nitrous after living with the supercharger for a time.

Nitrous:

"Nitrous is an insurance policy" -My favorite saying. That is because you don’t need to use it every time you get in the car.Before I did the heads and cam work I needed it because the car only pushed high 13’s on its best day.With it I was murdering faster cars(motor only) because the extra 150hp made up for the weak motor.Now the car is faster and I rarely use it because it really isn’t neccessary for street cars that most people come against.Nitrous can destroy a motor if the timing is not set correctly,and the throttle must be wide open to activate the system.As long as your motor is tight,a 350 can take 150hp,a 305 125hp hit.Nitrous needs special considerations if you want to run a better cam and stronger heads.First,the exhaust to intake flow(in cfm at cam lift points) should be 80% or better;second,nitrous responds better to dual pattern cams(more exhaust duration and lift than intake) to evacuate the extra exhaust produced by nitrous;third,nitrous systems need an adequate fuel supply that if not met,cylinders go lean and pistons melt from the heat;fourth,the faster the car is,the less nitrous will help.For example on a stock motor 150hp of nitrous gave me 15mph,now the same 150hp gives me only 13mph.

Friction:

Friction robs cars of power that is made,but never put to the ground.Using synthetic lubricants will reduce friction,roller rockers also reduce it,underdrive pulleys free up hp used to turn accessories…etc.All things that actually reduce friction will make the car faster.All weight taken out will also make a car faster,but don’t overdo it.

Trans and Rear:

Most camaros/firebirds came with TH700R4 automatics,and a few came with T-5 manuals. TH700R4’s are only adequate for 300hp motors with stock parts,built ones can easily handle 500-600hp continuously.I don’t know the limits of the T-5,but there are a lot of 12 second cars with them.I had my TH700R4 done by Level 10,it is relaible and shifts like a mother,Art Carr,Rossi,and Darrel Young all do first rate TH700R4’s. Stock rearends that came with 3rd generation f-bodies are good into the high 11 second range,after that they break.If your car is faster,go with a Ford 9",they are they strongest and cost the same as a Dana 44 or 12 bolt chevy rear.The most important item about rears is the gearing.The perfect gearing puts the car at it’s power peak at the end of the quarter mile in your 1:1 transmission gear,you cannot go faster by under or over revving the motor when you hit the traps, period.My car runs 121mph in the quarter,which is exactly the 5500rpm power peak of the motor using 3.42 gears and 150hp nitrous.Had I not the nitrous 3.73 gears would put the motor at 5500rpm at the traps.Anything over 3.73 is overkill on the street,and you cut top speed of your car.