ESPN's Tim Brewer answers your questions

Former championship crew chief and current ESPN analyst Tim Brewer answers questions from ESPN.com NASCAR Icons readers.

Updated: August 5, 2008, 3:45 PM ET
ESPN.com

We know NASCAR fans have a lot of questions from watching Sprint Cup races, so we went to one of our experts for some answers.

Tim Brewer
Rich Arden/ESPNTim Brewer shares his years of insight about the inner workings of engines and NASCAR with readers.
ESPN analyst and former championship crew chief Tim Brewer has many years of experience from working on NASCAR teams and has offered to share his knowledge and connections.

ESPN.com's NASCAR Icons gathered some of your questions earlier this week and Brewer obliged with the following answers:

When the jackman drops the right side of the car; the car jumps forward. What causes this?
RL Jackson,
Rocky Mount, N.C.

Brewer:
When the driver coasts into the pits he's got the car out of gear. What the driver's doing is basically trying to get a cool drink of water. But when the right side of the car comes down he actually reaches over, pushes the clutch in and puts the car in first gear. And that's when the tire jumps forward.

In the process of doing that, the right rear tire jumps forward and hopefully the right rear tire changer has all the nuts tight at that point because if he doesn't it kind of messes up his rhythm a little bit.

Could the tire issue at Indy -- wearing down the right rear -- be from the teams twisting the cars to have that sideways look?
Mike
New Orleans

Brewer:
Mike is exactly correct. When you've got camber in the wheel [meaning from top to bottom and you've got negative camber in the wheel] you're loading the tire to where it actually has the benefit of the corner utilizing all the rubber on the tire [meaning keeping the tire from rolling under].

But with the tire being toed out it also creates drag and friction on the right rear tire. And any time you create more drag and friction on that right rear tire you induce more wear.

Andy Petree mentioned [during the ESPN broadcast] "turning the engine backwards" after Kevin Harvick's spin at Pocono. How does that happen and what does it do to the engine?
Ricky,
Naylor, Ga.

Brewer:
Kevin Harvick deserves a lot of credit there because when you drive off in that corner and you're anticipating "well, I've got to get back in the gas." And all of a sudden something hits you from the rear and you turn the car sideways, he stood it back in the gas just as hard as he could and really tried to dirt track the car and keep the momentum and save the car.

But at the same time he was having those wheels spin forward. That's all a good thing because when the car started to go around the other way, Kevin had to get the car either out of gear or the clutch in because the first thing that happens when you go backwards, you turn the engine backwards, the oil pressure stops. And when that belt stops turning, and turning the other way, it can actually kick the oil pump belt off. It can spin the engine backwards where you have no oil pressure.

It can also create a lot of damage because even the lifters in the engine in the camshaft are designed on a ramp so that they're going up and spinning the lifters. And when that engine starts going backwards they actually chatter on the camshaft. It creates devastation for the engine.

But Kevin Harvick did a great job because he tried to save it as much as he could and when he found out, "hey, this is a lost cause," he had to spin the car the other way. But he did a great job because he finished fourth in the event. It tells me he had no engine damage. But all of this is happening in a matter of seconds.

You just think, that engine's all of a sudden turning 9,000 rpms one way and the next thing if the guy doesn't implement proper procedures everything goes away and the thing is actually turning rpm backwards. But the oil pump getting kicked off and the oil pressure is the biggest related problems.

I have heard it mentioned on several NASCAR broadcasts that the dry sump pump pulls a vacuum in the crankcase to help the engine make more horsepower. How does this help?
Jonathan Whitfield
Millbrook, Ala.

Brewer: As a matter of fact, back many years ago I built an oil pan on one of Neil Bonnett's cars. And what we did, we put an extremely large oil pan on it -- something that NASCAR just said, "hey Brewer you just can't bring this thing back" -- but what we were doing we were creating more square inches in the oil pan trying to get the oil away from the crankshaft. You've got an area in there and we literally run scrapers in the oil pan to pull the oil off the crankshafts and the connecting rods. But we found out we can actually take the oil pump and use the scabbing side of the pump and we literally sucked the oil away from the connecting rods, the crankshaft.

And as a rule, when you have that oil in there it really detours rpms. So you actually suck that oil off there because if you literally look down in that engine when it's running at 9,000 rpm, if you didn't have that suction side of that pump it would be looking like a fire hose spraying on the crankshaft and the connecting rods.

So anything you can do in the effort of making the engine accelerate quicker by getting that oil off the crankshaft and the rods, and even under the valve springs, you're going to have a very, very effective engine as far as acceleration and power.

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