Trying to choose between the B13 Se-R and NX2k as my future track car. So some questions for you racers/time trialers.

Are you guys hitting top speed in your cars while racing or time trialing?

I'm trying to figure if fuel cut in fifth gear is even reached in our cars in a racing situation. I'm like 90% I'm going to build up a b13 for the track. Now which b13 to go with I'm not sure. I'm leaning more towards an NX2k as opposed to the Se-R.

I know the NX2k enjoys an advantage as far as Coefficient of Drag. I'm just wondering how close an ITA or PTD-PTF car gets to reaching fuel cut in fifth.

Here is what I'm thinking as far as the pros between the two cars.
NX2K: Better Cd, AD22 brakes stock, lower roofline
SE-R: Body Panels are easier to find, better frontal cooling area, Possibly stiffer because of Coupe body compared to NX2k Hatcback design.

If you guys have some data regarding top speeds reached down a particular straight please let me know. Also some opinions regarding the choice between a hardtop se-r or a hardtop NX as far as a better platform for racing.

SOme points that would be good. Track where data was gathered, Final drive Used for your car, Wheel/Tire Size, Category for car (ITA, PTD,PTE,PTF, etc).

Fuel cut depends on track. At Summit Point, main track, I am hitting over 120, on shenandoah, a little over 100.

N2K has the aero advantage, but Sentra's are more available.

You will need to mod the ECU for the fuel cut at the very least.

I have a B14 in ITA trim with stock gearing, but they are pretty close performance wise to the B13's. Maybe the B13s/N2K are a small edge in performance due to a better suspension and brakes.

You will need to mod the ECU for the fuel cut at the very least.



Bill, B13's don't have a limiter.


FWIW, I don't even get all the way to 5th at Mid-Ohio even with the 4.4FD in my NX. Greg or Crazy Joe might though. From watching their incar vids I don't think it's possible to get to fuel cut in 5th on track. With IT level prep I think you'd run into an aero wall before gearing became an issue. My .02.

Correct me if I'm wrong, but wouldn't the Sentra chassis offer more rigidity than the NX? (assuming the NX has t-tops of course) I can't imagine that a hard top NX and Sentra would differ that much in that aspect.......

Oh I'm not considering Ttop NX2k's. Only hardtops. Either a proper 2.0 or a 1.6 with a swap.

My main thing is if these type of cars even get close to rpm limit on fifth gear. I'm thinking that would be where the aerodynamic advantage would make itself apparent. Unless the NX benefits from its aero at lower speeds. I might only be a 1 to 2 mph difference but throughout a race that kind of advantage adds up.

THank you guys for responding. It seems that the B13's aren't reaching top of fifth during a race.

I'll have to read more about the advantages of a lower Cd and the Nx's lower roofline which I'm guessing means it has a lower center of gravity as well.

I would go for the Sentra. There 2 mains advantages:

Weight and body stiffness. Depending of the racing class, you can put NX stuff on the sentra like the brakes and the sway bar.

I don't know the exact weight difference, but for a N/A car it would be noticeable on the track.

Mart

My main thing is if these type of cars even get close to rpm limit on fifth gear.
No where near it, not even with a 4.437 final drive. The aero drag at speeds above 100 mph is so great that you'd need a HELL of a lot more horsepower than most rules allow. I don't recall exactly (I can look it up if you really need to know) but my top speed in the NX at the downhill end of Road Atlanta's back straight was around 126 mph.

The only functional mechanical difference between an NX and a Sentra is the brakes (SE-Rs can't use the NX brakes in SCCA). However, Joe DiMinnno's illustrated that this is not a functional problem in reality. Further, in reality, differences in prep and errors on the part of the driver far exceed any actual (or perceived) aero advantage of the NX.

Were I to build a new race car today I'd build a Sentra, simply because of the availability of chassis (unless someone gave me a freebie hardtop NX; I just have a soft spot for the coupe). Put a killer cage in it, prep it to the nth degree, and go kick butt.

GA

Like Greg said no where even close to cutting out in 5th gear. My all time top speed was 131 mph Data Aqu. confirmed at Pocono. It was running the old SCCA config. using 80% of the front straight turn 1 nascar, long pond strait.

Oh yeah build a Sentra, NX's are gay. ;)

^^Good info. I was hoping Greg and Joe would share their opinions. These are the perfect guys to get an opinion from, regarding NX2k vs. SE-R in race conditions. Since they have raced each other.

Looks like I'm gonna stay with the Se-R hardtop that is sitting in my garage. Hey if Greg Amy says he'd build a Se-R that definitely counts for something.

Joe do you use ducts to keep your AD18's cool?

what kind of lap times do you see at mid-o in a b13 anyway?

what kind of lap times do you see at mid-o in a b13 anyway?

I'm slow and turn 1:47's.

Joe do you use ducts to keep your AD18's cool?

Brakes what brakes? ;) I do not use any ducting. I really should try it some time it may make the pads last a little longer, but i have never had a problem with them fading or anything. The secret is to use them as little as possible. :)

what kind of lap times do you see at mid-o in a b13 anyway?

I ran low 1:44's last year at IT fest on the club course with a wopping 143 whp (dynoed after the event) and the year prior at NASA Nats ran a low 1:42 on the pro course.

I am hoping for mid to low 1:41's at It fest this year on the pro course. New engine soon to be completed. :D

I'm slow and turn 1:47's.

Not slow, conservative. :D

I haven't had an opportunity to run the pro course yet at midO Every time I;ve been there so far is with the kink.. doh

I haven't had an opportunity to run the pro course yet at midO Every time I;ve been there so far is with the kink.. doh

You're not missing out on anything. I'm a big fan of the kink.

AFAIK NX is stiffer than SE-R even with t-top. My hardtop NX is much better handling than the SE-R and I attribute that mostly to the chassis stiffness. My .02 ymmv.

AFAIK NX is stiffer than SE-R even with t-top. My hardtop NX is much better handling than the SE-R and I attribute that mostly to the chassis stiffness. My .02 ymmv.


Oh, so you've prepped up an NX and an SE-R to the limit of IT or PT rules and done extensive on-track testing to see which is better. Excellent.:biggthump

Can we see the data?

Can we see the data?
My pleasure
http://upload.wikimedia.org/wikipedia/en/0/09/DataTNG.jpg

My pleasure
http://upload.wikimedia.org/wikipedia/en/0/09/DataTNG.jpg

What a clown LOL!!