SAM WINEGARDEN INTERVIEW ON THE 2002 LS6
Sam Winegarden, chief engineer for GM Powertrain's small block team, was recently interviewed on the launch of the 2002 LS6. The LS6 is the 5.7L V8 engine for the ZO6 Corvette which will break the 400 horsepower mark. Sam has been Chief Engineer for the small block program for a little over three years.
1) Can you describe what it's like to work on the small block program?
If you talk about imaging and brands and that kind of thing thereís nothing longer living, better recognized than the small block Chevy. When you come to work here your working on an icon. You're also working on the heart and soul of the Corvette and almost every truck we make. Virtually half of GMís North American volume and a large part of its profits centers around the small block. Itís fun but itís pretty sobering. Youíre in charge of a legend.
We've been really energized around here with the introduction of the new LS6. Producing horsepower is always exciting and generates a tremendous amount of enthusiasm. The ability to match the LT5 certainly generated a lot of enthusiasm for the team, I mean itís another step, another level of performance in the history of the small block and the team was pretty enthusiastic about going after that. It was a lot of fun.
2) With 405 HP in the LS6 you've surpassed a lot of the muscle car era's gross power levels [1968 L79 327 - 350 HP, 1969 L46 350 - 350 gross horsepower, 1970 LT1 350 - 370 gross horsepower] with these kinds of numbers - that's definitely an achievment.
John Juriga (assistant chief engineer) and his team have done a really nice job with what you could call the ruthless pursuit of horsepower. The small block team has done an excellent job of bringing every bit of horsepower they could out of it. To say the least, the accomplishment is thrilling to be a part of.
3) You've achieved comparable power to the legendary LT5 with an OHV design. Any comments on this historic achievement and its impact on the industry?
It's just one more step in a long and very storied and successful history of the small block. The team is just continuing to perform at an outstanding pace. From an industry perspective I think one thing it tells you is that there is more than one way you can design an engine to achieve the power. The conventional wisdom out there will tell you that you need to have a four valve overhead cam arrangement and that is just simply not the case. You can make it work either way and I think John and the team have shown that. From an industry perspective it just tells you that the push rod small block has a bright future, and thereís more where that came from.
4) Do you think this power boost will resonate well with the Vette fans?
Absolutely. 20 HP doesnít ring like itís a really big number but when you actually drive the vehicle, to quote Dave (Dave Hill, Corvette Chief Engineer and VLE), it makes the car really come alive.
5) Did you meet the Corvette team's requirement for power and torque levels?
Yes, actually we exceeded them a little bit. The objective was 400 we got 405.
6) Having been the Chief Engineer for GM's Premium V engine family [which includes the Cadillac's Northstar and Oldsmobile's 4.0L and 3.5L engines] for 10 years, what type of engineering processes are carrying over into the small block?
Thereís a lot of synergy in several areas, one of them is our Bill of Design. Bill of Design is basically a guideline of best engineering practices established over our collective life to get the best possible design. Now granted one family of engine is a four valve and one is a two valve push rod, ones overhead cam and oneís cam-in-block. Many elements of the Bill of Design on things like cylinder head design, block design and piston design carrys over regardless of a particular architecture, so thereís a lot of similarities there. One of my favorite examples is the structure on the bottom end of both the Vette and the Premium V. While there are two different solutions there, oneís a deep skirt with a six bolt arrangement and oneís a bed plate, both of them are just outstanding from bottom end structure and both followed our Bill of Design. The small block is probably the most robust lower end Iíve ever seen, bullet proof. The team did just a superb job there.
7) What do you think the guiding philosophy should be in the development of engines for the Corvette?
Well the first thing, the Corvette has to be the best performance value on the road, period - so of course you have to concentrate on the power. The other thing that you have to do is integrate the engine into the vehicle. If you just make raw power and donít get it integrated into the vehicle correctly then itís not going to be very pleasing and frankly the vehicle wonít be very exciting. Working with the Corvette team has been a pretty rewarding experience because together weíve been able not only to make that kind of legendary performance number but package it in a vehicle thatís actually very refined for the level of performance that youíre getting. The overriding principle is: Itís got to be done in a quality manner, making the horsepower then breaking engines is not a good plan.
8) For '02 the LS6 increased 20 HP. Why didn't you just give that last year when the LS6 was introduced?
To be bluntly honest with you, we werenít quite ready. There were some valvetrain issues we needed to work on. Reducing the mass of the valves and working with the aggressive ramp rates on the cam were challenging. There were other challenges obviously but I think the valvetrain was the trickiest to get solved and balanced. Weíre not going to do this thing if we donít have a quality solution in hand. Not having resolved those issues in the final weeks before '01 production we agreed to do it as a two step process, 01 and 02. So it was purely a case of when we were ready. Weíre still not selling wine here before itís time.
9) Did you ever consider expanding the bore or stroke?
Some of the learning from the power development in this program is destined to show up in future model years.
10) The rpm limit of 6600 rpm is impressive for this pushrod V8. Why is the LS1 (in the base Corvette) fuel cutoff at 6200?
We've reached a threshold around 6200 rpm where we needed to reduce the weight of the valves to avoid fluttering. When you have a heavier valvetrain one of the things you trade away is some of the higher rpm capabilities and you end up having to limit the speed, thus the lower speed of the LS1. Itís a trade off of how much power you want to make versus how much fuel economy and/or how smooth and quiet you want it to be and thatís a balance we struck with Dave's team.
11) The LS6 beauty covers are red, distinguishing it from the LS1. Was there any discussion on visually distinguishing the 2002 from the 2001 LS6?
No. However the engine is getting credit on the exterior of the car. There will be a badge with "405" integrated into the ZO6 logo.
12) What is the volume projection for the 2002 LS6?
We will start at 20 percent of production at Bowling Green, and see what the demand is for this special model. Either way, the St. Catharines Engine Facility will be locked in and produce what we need.
13) Did removing the pup converters create more emissions?
No, we took care of that by improving the under-floor converter. Converter technologies is one of the good technical stories unfolding across all GM Powertrain that we were able to take advantage of. It obviously helped us with our power by cutting the back pressure in the exhaust system which is always a good thing to do.
14) Will this version of the LS6 still operate fine with regular fuel? Is premium fuel still recommended?
Yes, premium is still recommended and yes, it operates just fine with regular - the ESC [Electronic Spark Control] system adapts to it. There is of course a slight degradation in performance. The two areas where you'll lose a little performance is at low speed heavy load and then at top end. Pulling the spark back will reduce the torque a little. Driving around town you won't really notice. On the track yes, but around town just use a little more pedal because there's a lot there.
15) What's your favorite year Corvette?
The '02 Z06. If you canít get out of that car with a grin on your face you're in the wrong business.
16) Then what's your second favorite?
The 1963 Stingray. Historically, thatís the one I like best.