treyZ28

I tried searching around- but I was thinking about this. Since they only turn left and given the driveshaft rotation direction- with enough wheel bias, the only wheel that would be powered would be the outside wheel- which is ideal.

So do they run an open rear? Well, I know the answer is no because i've seen them do burnouts. I guess the question is "why?"

Old SStroker

Yes and no. On big tracks where off-the corner traction isn't a problem it's open. On short tracks and road courses it's probably something like a Detroit Locker.

Anyplace where the engine rpm runs 3 or 4000 from lowest to highest traction will be a problem, so some form of limited slip is used. IF there was traction control in Cup cars the tracks that needed it would also be the tracks where a locker would be used.

Especially on a long high-speed tracks any form of locking diff would cost power. As a possible added benefit for the "plate" tracks (Daytona, Talladega) spinning one tire launching out of the pits keeps the engine from bogging or stalling. Notice how long they are in first gear on pit-out @ Daytona. It's not just used for getting the car rolling. Trying to spin both @ Daytona might be a problem with an engine weaker than most H&C LT1s.

Did you notice that the highest horsepower car on the track @ the Daytona 500 was the stock Z06 pace car?

Steve Bryant

iTrader: (1)

No, I didn't, but that's a sobering thought on the state of affairs with a production Chevrolet. I wonder if the ZO6 ran any unofficial qualifying laps just for grins!

Steve

CTSmechanic

iTrader: (2)

You used to be able to run an open diff.. at Speedways like Daytona and Taladega... but its lockers on all tracks now.... The pace car might have a small bit more Hp but I'd like to see it hang in the draft.... that would be funny too see a pack of 10 cars pass it like it was in reverse.....

Gary Z

I don’t follow NASCAR but while zapping through the channels Sunday, I noticed engines turning 9500 rpm. At 350 cubic-inches they are probably making at least 700 hp.

Wnts2Go10O

iTrader: (12)

800ish...
the thing about the plate tracks is that they rely more on the draft for speed. the Z could do it without the draft. the true test for it would be if it could hang in the turns. which according to the nurburgring lap times...it should be able to do it without trying. the Z is a better handling car overall. id just like to see the motor stay together with the abuse the plate tracks put on the motors

Billy the Great

iTrader: (2)

not on a restrictor track. I have watched a restrictor motor make 44x hp on an engine dyno so they do make less hp than the pace car

Old SStroker

You were watching California, an unrestricted track. More like 850 hp from the 358 cubes.

Daytona and Talladega have restrictor plates. HP is closer to 425 and max rpm closer to 7500 at those tracks.

2000TransAmWS6

iTrader: (12)

when i was going to the Nascar Technical Institute in Mooresville our 358ci Dodge motor made 738 hp and just over 550 ft/lbs on the engine dyno. we were limited how high we could turn the motor, but the school record was set by one of the instructors (who had 10 years of Cup motor building experience) who made right around 750
and i think we made in the 680s hp to the wheels on the chassis dyno.

CTSmechanic

iTrader: (2)

I dont know how you'd compare the nurburgring to Daytona..... I would be willing to bet from pace car speed the cup car would out accelerate the vette... Theres no way that a stock suspension vette would be able to run through the bumps at Daytona

3.4camaro

iTrader: (1)

big bronco (mod on here) from SAM caem to my school and did a presentation on how much School of Automotive Machinists rocks. He said they have about 600 hp, and about 300 with the plates on.

CTSmechanic

iTrader: (2)

Ummm...those wouldnt be accurate numbers......

3.4camaro

iTrader: (1)

hmm... go yell at big bronco then.

blackz93

iTrader: (2)

Some are a little better than that!

ChucksZ06

iTrader: (9)

A while back we were having a discussion here about how much horsepower the restrictor plates cost a nascar engine. I was quoting folks who said the nascar engines would make substantially more hp with a larger unrestricted carb. You said no way. Now you are saying the hp would almost double. I do not pretend to know the exact amounts but both statements are not true. BS is BS. I would be more inclined to believe the numbers you state in this post.

AdioSS

iTrader: (2)

Are you sure that's what he said? Are you sure he was talking about Cup engines and not ARCA stuff? Both are "NASCAR" engines, but Cup is the big stuff. That sounds a lot more like the numbers we were getting from ARCA engines when I was at SAM a couple years back.

CTSmechanic

iTrader: (2)

Auctually some ARCA motors make more HP than a cup motor simply because they can run a roller cam

nycab

iTrader: (7)

I thought they used Detroit Lockers. Not a huge Nascar fan cause I just can't sit still for that long and I'm not old enough to go and drink all day.

tim99ws6

iTrader: (31)

they use lockers, open diffs(which i think might be illegal now), and spools depending on the track. I got one of the NASCAR cup car Lockers from a shop in NC. It's in my 9" now, and MAN, this thing is a work of art, haha.

CTSmechanic

iTrader: (2)

No spools no opens no tru tracks...31 spline locker... of course you can adjust things in the locker.. but thats another story...