DragNC

Morning,

I'm in the early stages of building an NC for drag racing and I'm here for some advice on my options for the rear diff.

So far I've collected pretty much everything I need for the engine and I have the car but I think I've got a bit carried away without considering what I think will be the weak point.

Arca_ex

iTrader: (2)

Not enough information to help you. Your options for a rear diff setup are going to depend on how fast you want to go, how serious of a drag car it is and how much power you make etc.

DragNC

Fair points, I was planning on making a more in depth thread in the right subforum but a quick rundown for now;

2.5 with rods and pistons, G25-660 for now, water to air, hoping for mid-high 600bhp to begin with. 24.5x8x15 slick.

My end goal is repeatable low 10s.

I know I can make the power, and I know the NC rear end won't cope with it. The easy choice is RX8 parts but I don't think that'll work either.

The biggest hurdle is that I'm in the UK so I don't have the luxury of cheap Ford 8.8s...

Newaza

What kind of fuel do you plan on running? What transmission? As Arca mentioned more info is helpful.
Have you considered using the g30 turbine side? I would be very surprised if that g25 turbine would actually support 600whp. Turbo would probably be lively but the exhaust manifold pressure vs intake pressure would also likely be very high which might make the engine more prone to detonation.

sixshooter

iTrader: (12)

Removing weight and/or not adding unnecessary weight will help reduce drivetrain load and preserve the components. Not adding additional failure points and complexity are also great ideas for race cars. This is why everyone with a turbo race car here uses an air to air intercooler.

Is it going to be alcohol fueled?

Have you built any previous drag cars? If so, pics and descriptions including weights, ETs, and trap speeds will help us better understand your capabilities and may help us advise you better.

DragNC

The recommendation I had from a friend who races a Civic here was the G25 for that power (6xx at the crank) so thats what I’ve bought but now you’re making me question that choice. The G30 would mean I could go bigger within the same frame size in the future. I’ll speak to a couple more people.

Fuel I’m still unsure about, I know it won’t be E85 because it’s not as readily available here as it is in the US, we can get VP from a couple of suppliers so probably something they offer. I am yet to buy injectors so again, that’s something I need to consider beforehand.

I plan to use the stock Aisin 6 speed, they’re cheap and easy to find, plus there’s a few variations in other cars with slightly different ratios.

DragNC

This will be my first drag car build. I’ve built several track cars and a race car before and I have a few friends who drag race who are strongly encouraging me to come and play. The only issue is, they’re FWD guys so can’t really offer much in the way of help with setup.

My reason for using a water/air setup was that it gives more flexibility with where I can mount the weight. I see your point though, it means more wiring, pipes, water pump, water box… like I say, a lot of what I’ve bought so far was recommended by friends who don’t have a similar car.

As for the fuel, as said above it’ll be something VP sell but at the moment I’m not sure exactly what.

It’s the early stages of the project and there’s still some things I can change. What I don’t want to end up with is a car which is powerful but keeps grenading the rear end, leaving me with no option but to throw money at trying to fit a 4 link and a 9” to a tiny wheelbase.

DragNC

Other than the suspension I have nothing which strictly binds me to using the NC which I’ve bought. It’s just what spurred the project on, it was £650.

If the car is going to be problematic I can split the car, sell the suspension and put the engine combo in something different entirely. That’s really what I’m trying to find out here. Am I chasing an idea which just isn’t realistic with that car.

Newaza

You stated looked for lowish 10s in the 1/4 mile, That means somewhere in the mid 6s 1/8th mile. Its certainly doable and wont be any more problematic than making any other slow 4 banger car fast.

Arca_ex

iTrader: (2)

Well, you're not going to like this but seems like a Ford 8.8 swap is the best route for what you're wanting to do...

Newaza

if you are doing a drag car you may want to consider doing an automatic transmission. That would help stock rear stuff survive longer over a manual. You may want to check into this to confirm but I think the 2015+ 2.3 ecoboost mustangs use a 6r80 transmission that might bolt up to the 2.5 mazda engine????? Definitely do your research first though before spending any money on that as I am not 100% sure on that tranny bolting up.
If that is the case you can use a transmission controller like the quick 6 to control tranny. I've been helping a friend with a turbo godzilla swapped mustang with a 6r80 and i am studying up on the quick 6 now. Its pretty cool actually.
I dont know how the nc rear setup compares strength-wise to the nb stuff, but I've hit in the 6.50s in the 1/8th (equates to low 10s in 1/4) with the stock nb rear stuff using an automatic but axle breakage became an issue once I started pushing them that hard.

DragNC

That’s an interesting point. From what I can see, the 2.3 Ecoboost and the MZR/Duratec are very similar so I see no reason why that wouldn’t bolt up. Something I’ll consider for the future if I have significant issues with the manual.