Something funny...[Nitro Funny Car build thread]

its_all_Greek

Common name for them is money pit

RBZ5416

Don't know how you guys can invest so much time, effort & cash into something that could grenade on the first shakedown & leave you with nothing but a bucket of shrapnel. But I'm glad that you do!

Chevyonfuel

I could pinch the tagline from Birdman... The virtue of ignorance...
The underlying issue with nitro racing is that (as you know) you don't have to put all your cards on the table and have it set to kill, for it to result in carnage when something goes pop. The mitigation measures are limited as they can do an equal amount of damage by running the engine overly soft.

To get through the shakedown runs and generally the first qualifying run of a race weekend, we'd back down the nitro percentage, take some weight off the clutch, take some timing out of the mag....and see what happens. Fortunately the engine, clutch and transmission combination is relatively simple and finding a baseline. It's always a bit of a moving target though, on a good day you could roll up to the track and not hurt anything, another day, with the same tune-up, it could pinch a piston if the ambient air is a bit better than you expected - we all pretend to be Michael Fish at this point and reach for our weather stations.

The Chevy motor I ran previously wasn't as easy to work with, so we were chasing our own tails trying to find a baseline, while still trying to tune for the track, ambient air etc. I was also young and stupid back then...

Chevyonfuel

Yesterday the valvetrain geometry was checked to ensure no push rods foul the heads, and no springs go into coil bind. Whilst this layout is by the far the best for making power, the nature of the geometry makes the design itself quite vulnerable to damage if something is just a knats off from being correct.

                                                                                                                                                 
http://s264.photobucket.com/user/topfueldigger/media/NFC/FB_IMG_1431490693872_zpsxm0iiynm.jpg.html
With Chevy or Ford engines, you only have the deck height, cam tunnel height and rocker ratio to check when looking for push rod length (heads generally hover around the same deck thickness), so you can buy parts off the shelf and have a good idea they’re correct (they’re more likely to be a nice round number at least!). With the race grade Chrysler motors, you have the deck height, cam tunnel height, head deck height, rocker stand height and rocker ratio and push rod type to check – there’s all manner of variables as people like to do things differently.

As I like simple, the block deck height is -0.500”, with a regular cam tunnel, standard deck heads, standard Keith Black rocker stands and nothing outrageous in terms of rocker ratio. It all fitted together quite nicely and spare push rods should be easier to come by later down the road.

Next up is the blower setback plate which moves the blower back on the manifold a few inches. Due to the blower discharging at the front of the case, it’s better to move it back to help get that air into a more central location in the manifold. After that it’s just the burst panel cage to fit before moving onto the fuel system.

Chevyonfuel

July update…

On the engine front, most of the supercharger drive components have been installed. These are comprised of the blower snout, top pulley, burst panel cage and belt guard / starter bracket. As is the case with most race parts, they require trial fitment to work out things like belt length and snout length – you can just see the ‘missing’ manifold bolt, this is now a countersunk bolt, with the blower situated a few inches rear of the standard location.

                                                                                                                                                  

Due to the discharge path of the blower, the revised placement helps ensure that boost pressure in the manifold is a little more uniform. You can see from the top pulley location relative to the starter bracket offset posts that surround the top pulley (these are meant to sit flush with the front face of the pulley), how far set back the blower is (a longer snout is used to span the gap between where the blower sits and where belt arrangement sits). Longer offset posts are on the way, along with the starter jaw which features teeth that mesh with an off board starter motor.

Some machine work was necessary to get the setback plate and manifold to fit. One of the bespoke amendments to the manifold was to fit rails to the front and rear, which are lined with rubber strips. These aren’t specifically for alignment purposes (though they do help), but in the event of burning a piston, this prevents oil pushing out through the front or rear of the manifold. It tends to be the case with most American V8’s that the weak spot in terms of manifold sealing is the front and rear face, which leak more than the intake gaskets (with the Hemi, a switch to O-rings rather than gaskets helped mitigate the issue of gasket material being sucked in and jamming an intake valve open).

The motor is now almost complete bar for installing the fuel pump, magneto drive, ignition system and safety blankets top and bottom (Kevlar bags around the sump and supercharger, along with high strength straps to limit the movement of the blower if it gets launched off the manifold.

There's some progress in other areas (the body in particular), which will follow quite soon.

Chevyonfuel

Something other than engine parts... the body...

I was always a fan of the late 70's Corvette, so the choice of what to clad the chassis in was clear, I just needed some inspiration to get a paint scheme that worked, that brought out the curves of the body.

                                                                                                                                                 
Back in period, most Vettes made use of the natural curves in the rear of the body, around the wheel arch, to add some swoopy curves. This in conjunction with my favourite paint scheme, the Super Brut / Faberge livery that generally ran on Dodge bodies (Omni Charger etc), meant something unique, with a tie-in to the past, but also keeping some continuity with my last car, at least in terms of colour.

I quite like the end result

RBZ5416

Spooky - I meant to ask about the body after your last post & somehow forgot. That's stunning.

Takes me right back to Tom Hoover's Showtime.

Chevyonfuel

Some more of the same for August, engine bits...

With the exception of the fuel pump and ignition system, we're pretty much there.The billet oil pump has also been installed, which feeds the dry sump from a tank mounted at the front of the chassis which is paired with the fuel tank.

Next month, hopefully there'll be some news, and photos and wonderful stuff...honest...

RBZ5416

Will the power limits allow your class to run the full quarter or will you also be limited to 1,000'? Can't believe it's seven years now since Kalitta's death.

Chevyonfuel

At present it's 1/4 mile for all the nostalgia nitro classes. The same is true in the US; the quickest guys over there are running in the 5.5 zone at 260mph in Nostalgia FC, which is bonkers with a 21gpm pump and tiny blower, but proof of what's possible with small kit and some brain power. In terms of the 1000' deal in Europe, most of the tracks themselves have long enough shutdown areas to allow 1/4 mile racing (Santa Pod in particular), but due to the desire for parity between the NHRA and FIA, the decision was taken to shorten the distance in Top Fuel and Fuel FC.

The byproduct, which is a benefit to the FIA nitro teams is that data and tuning is still comparable with the US. There's been zero cost saving in shortening the race distance, as they're simply pushing parts harder than before, over the shorter duration (and now reaching the same speed at 1000' as they were at 1320').

The European Nostalgia FC rulebook states "Speeds of 250 mph and/or elapsed times in the 5.90-second range will require a re-evaluation of performance restrictions." However, it's unlikely we'd see any changes, as like the NHRA / FIA parity, we currently have parity with the NHRA Heritage Series, which governs the Nostalgia Nitro classes over there.