The Spintron engine testbed has become a staple for engine andvalvetrain testing. This big
Performance tricks are usually just sleight-of-hand changes that dolittle to improve performance. After all, if it was that easy, everyonewould be doing it, right? But the simple fact is, valvespring technologyhas been moving on--in giant leaps these days. Ask any NASCAR enginebuilder behind closed doors, and he'll tell you about his lightweightretainers and valvesprings, perhaps the most significant change in thelast 10 years. These beehive-shaped springs feature a lighter retainerand a lighter-weight spring. The effect is a better-revving, moredurable engine, and a big-block that revs like a small-block.
What does this mean for your street-driven Corvette? The same newtechnology that helps improve the performance of Jeff Gordon'ssmall-block can work for your big-block (and small-block) Corvetteengine. Through extensive testing, Comp Cams has created the ultimatebig-block "beehive" valvespring, which you can add to your currentengine (without having to take it completely apart) or your next engineproject. The benefits, as we found out during our comparison testing,were more far-reaching than just the obvious improvement from simplyinstalling a set of fresh springs. As it turned out, the change alteredthe personality of the entire engine and allowed us to do someinteresting performance enhancements.
The Spintron uses this specially modified big-block engine with sensorslocated throughout.
The Spintron has changed the look of engine component testing today.It's a device that spins the valvetrain (with the lower end of theengine removed) while four sensors, high speed cameras, and lasers mapout the internal dynamics of what's going on inside. Comp Cams' Spintrontesting program helped develop its new beehive valvespring.
The beehive spring shape has become the buzz lately, and it's commonlyused in many OE engines as well as Nextel Cup competition. Why? Thebeehive shape is more stable than standard cylindrical springs, as welearned in our testing. The benefit? Larger valve stems, like thosecommonly used in big-block engines, aren't required.
Valvesprings now come in different strengths and different shapes. Thetwo springs on the r
With performance engines, weight is the enemy. Valve retainers arecostly items, but the weight savings is real. The entire titaniumvalvespring retainer business is based on the need to lower valvetrainweight to improve performance. Lower-weight valvetrain componentsimprove the durability of the engine, allowing it to rev higher andquicker. If valvesprings are the limiting components in today'sbig-block engines (and they are), making them better and lighter is abig deal.
"Beehive springs feature smaller, lighter retainers, greatly helping theengine achieve much higher peak rpm," said Chris Douglas of Comp Cams."That allows the engine builder to switch to higher-lift, moreaggressive camshafts to increase performance."
Our test was to compare cylindrical valvesprings to the new beehivesprings. For the test, we used Comp Cams' big-block engine on theSpintron. We featured their traditional 924 cylindrical springs withtitanium and steel retainers. This very traditional yet high-performancespring features both an inner and an outer spring. Total weight of thespring, as noted in the chart, was 140 grams. The beehive spring (PN26120-1) is a single-coil spring. The total weight was 99 grams. Whileit may appear the dual spring is stronger than the single-coil beehive,we were told the comparison was a good one.
Our lightest retainers were made of titanium, and this beehive retainerweighed 9 grams.
"The beehive design, which incorporates the ovate wire (a uniquelyshaped and innovative design), does not require a second inner spring,"said Douglas. It's more than capable of handling equivalent if notenhanced performance demands. That is one of the main benefits of thespring--lighter weight and better performance."
The ovate wire used in the beehive spring is a teardrop shape ratherthan round. According to Comp, this allows the spring to deliver betterperformance with less seat pressure and better durability. Sounds good.Now it's time for the test.
Weight A Minute
The beehive retainer, in steel, weighed 15 grams.
The test began by installing the 924-1 cylindrical valvesprings on theengine and chucking it into the Spintron. We used both steel (test No.1) and titanium (test No. 2) valve retainers, along with 3/8-inch steelvalves and steel valve locks. We ran the engine up to 7,000 rpm andwatched what happened.
For tests No. 3 and No. 4, we installed the 26120 Comp beehivevalvesprings. Again, we used steel and titanium valve retainers. Whilethe look was considerably different, there was no difference in sound orany required part changes. The same valve locks were used as well.Obviously, the biggest change was the weight. The retainers weresignificantly lighter with the beehive units--dead weight, according tothe Comp engineers. "It's like installing titanium valves in yourengine," said Douglas. "Guys spend a lot of money on lightweight valveswhen they can get the same effect and the better performance of thebeehive spring for a lot less money. These springs are not expensivecomparatively to standard cylindrical springs. It's almost like freepower."
What This Means
Our tests, as the charts clearly show, demonstrate that the beehivesprings, with less weight, are quicker revving and more stable than thetraditional cylindrical springs. Corvette owners who change springs withthe engine in the car can achieve the benefits of this lightervalvetrain mass. If your engine is older, a valvespring change can be aquick lift to the engine's performance. If you're ready for a camshaftchange, installing these springs allows you to select ahotter-performing camshaft due to the increased abilities of thevalvesprings to keep the valvetrain in line. If you're building anengine, these springs are a simple upgrade that any big-block enginebuilder should consider.
The steel traditional retainer weighed the most at 35 grams.
The traditional cylindrical-spring retainer weighed 19 grams.
The beehive spring weighed 99 grams. The spring's weight isn't ascritical as the retainer'
To perform at the level required by the beehive spring, the traditionalvalvespring require
This chart shows the performance of traditional-style ( Comp PN 911-1 )valvesprings (same
This dyno sheet, from Joe Sherman Racing, details the power and torqueof the traditional c
In similar fashion to the previous photos, this dyno sheet shows theimproved performance o
The beehive springs reduce weight as shown in this photo; the beehivespring is at top. Thi