Knock, Knock, Whos There? Help!

[TexasT]

I've had good experience buying from full throttle though I haven't bought a cam from them. Not even sure what I would order. Judging from what people seem to be able to do with stock stuff I'm not sure you need a very wild cam to make big power.

[Steve Wood]

I've had good experience buying from full throttle though I haven't bought a cam from them. Not even sure what I would order. Judging from what people seem to be able to do with stock stuff I'm not sure you need a very wild cam to make big power.

I saw 10.46 out of one of my friends car last year on a stock factory cam.  Cams are not nearly as important as a good set of heads and a big ol' turbo

Depends upon the projected usage and desired performance.  At some point, a longe/taller cam allows the turbo to get more air into the cylinders without working as hard-no doubt about that,

[reality]

 Nobody is suggesting to change cams just to gain a few HP. But if the engine is apart and you're going to get a cam anyways why NOT put an aggressive cam in your engine?
 If you are doing a stock style rebuild OK put a stock style cam in.

[Steve Wood]

I guess it is all in how you wish to define AGGRESSIVE as well as to what the actual INTENDED use of the car.

IF you wish to drive the car daily, have good throttle response, and get well over 20 mpg on road trips, and run well into the elevens, then a MILD cam, and  TIGHTER converter matched to the turbo will GIVE most people the MOST bang fro the buck.

IF you wish to build a a strip only car and don't care about street manners, then you may find more justification in a more AGGRESSIVE cam even if you cannot prove it by the time slip in all cases.

Given that I TOO used to run a Conley 221/221 cam, my own experience has been that a 210 cam provides much better street performance and that is not an  aggressive cam by my definition.  It also provides a tad more strip performance in my case.

I freely admit that I see no point in spending money that does not contribute to achieving my own goals and admit that your purpose may differ

I also admit that the 221 cam really sounded good out the exhaust between 5000 and 6300 rpm LOL

[larrym]

Like Steve says when your picking a cam keep in mind your converter and turbo. Moving the power band with a cam swap could lead to a converter swap and stiffer valve springs in order to take advantage of the full potential, you want to keep the car in the power band and that's all about converter

[Steve Wood]

Some of you may have seen the pics that Bison posted on FB.  Stock block with stock pistons that finally cracked a piston after a year of Mid-Nine second runs at plus 30 psi boost.  He listed the cam as a 3312/3312.  That cam lobe comes up as a 212 roller on the Comp site.  That's a pretty mild lobe for 800+ hp.

After 30 years of playing with these things, I am still amazed at what can come out of these things at times

[Scoobum]

212/212 off the shelf cam...roller or flat tappet take your pick...turbo.. . a good convertor.. a good set of heads...and boost...will get your ass down the track in a hurry. But no one listens.

[larrym]

I listen Brad!

[good2win22]

I read.... Then call Brad and listen. I don't have have Steve's number but I've heard him on the phone with William. 

[Steve Wood]

212/212 off the shelf cam...roller or flat tappet take your pick...turbo.. . a good convertor.. a good set of heads...and boost...will get your ass down the track in a hurry. But no one listens.

I have read many an article explaining as to how roller cams have more area under the curve, etc., but most dyno comparisons that I have seen that were truly apple to apple, give almost identical results on anything that is street worthy.  On turbo cars, this should be easily understood as the turbo trumps the cam in order of importance.  But, this seems to be often the case on naturally aspirated cars as well.

There is a glaring downside  to rollers...or maybe a couple.  Too short a duration and the valve train gets really violent which shortens spring life and become dangerous at a lower rpm with regard to valve float, lifter pump up, etc.  On the other hand, lifter weight may limit the rpm on hydraulic lifters no  matter what the lobe profile might be idealized for.  Trying to increase spring pressure significantly to increase the rpm range not only leads to lifter problems, but it also puts a lot of load on the front cam bearing and the oil pump/cam sensor drive.

Solid lifters are the answer to a serious race car but play heck with the knock sensor..but, then, serious race cars are going to get rebuilt pretty frequently so who cares lol

[Scoobum]

Bison has stated on more than one occasion that most don't run near enuf valve spring pressure. I run 135 lb springs with this off the shelf cam...and if you were to watch a PL file with the RPM gauge panel from one of my runs they climb so fast it would make most go screaming into the nite. I read a post from Dusty Bradford awhile back stating he was changing valve springs back in the day 3 times during a race season. Will my cam and lifters wear out prematurely... probably...but that's the cost of racing.

And most don't understand how important torque convertor selection is...and understanding RPM drop, flash stall and slip percentage should be required reading.

 P.S. One of the locals is putting XFI on his car. I'm gonna bury his ass with my chip. April 16th can't come fast enuf.

[1 RARE T]

Stock cams go mid 11's all the time. Fact. Ported heads are nice to tell your friends you have them. Cost too much to go a couple tenths quicker on a street car. The more you build it up, the higher you push the envelope. I would want to build it one time and not have to dig into the engine again for years.

Spend your money building it stockish, get a decent turbo, intercooler, 60 lb injectors, tight converter, alky kit, wide-band and good downpipe. Be able to watch what's going on in there with the right scan tools.

JMO.

[good2win22]

I would want to build it one time and not have to dig into the engine again for years

This is my philosophy

[Just a Six?]

.

[Steve Wood]

As we increase cam duration, the rpm power band rises. That obviously allows us to pump a lot more air and make more power on the top end.  The down side is that we lose power off the lower end and the entire power band shifts upward.  Race cars, that is not a great problem.  Makes the car sloppy if it is driven on the street.

We all know that the load on the engine increases as the square of the engine speed increase.  Given we have, normally, a cast crank and relatively fragile cast rods, there is some incentive to keep the rpm down if we want decent engine life.

The beauty of a turbo engine is that we can push a lot more air into the engine at low rpm which results in great low rpm torque and great throttle response whenever needed.  We therefore avoid some of the stress associated with increasing rotating stress although we still increase the stress in the combustion chamber from increased pressure.

People always want to try to use non aspirated engine theory on forced aspiration engines which is counter to the original purpose. 

Again, however, it is dependent on what you want to do with the car.  The faster you go, the more it costs, and the more often you will get to rebuild it.

Given that I don't drive many long trips, if there was E85 around here, I would be tempted to convert and eliminate the variability of alky injection on at least one of my cars.  That is just a side thought-not germane to the current discussion but after 30 years of this, I grow bored with the same old, same old.