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

Chevyonfuel

Luckily, a 3 or 4 second stab of the throttle would be enough to run quicker than a Veyron / 918 / P1 et al in the 1/4, so hopefully we have the Nova's covered.

RWYB events are OK for low horsepower cars, but it's rare to have the track glued as well as sledded, so there'd be traction issues .

Anyways, there'll be news on track action in the near future .

Chevyonfuel

Back to the spare motor side of the build, the heads and some other hardware showed up yesterday.

                                                                                                                                                 

                                                                                                                                                 

The heads are matched BAE billet early fuel heads, identical to those on the first engine. Some machine work is required just to open up the head stud holes, but other than that, they're good to go.

                                                                                                                                                 

Titanium retainers and locks along with new springs help keep the valvetrain in check. Manley parts I've used since the Chevy days.

                                                                                                                                                 

The same goes for pistons - Arias make some of the finest pistons available and can produce spares from your job card No. very quickly if necessary (fortunately it's not often needed - typically you'd order a box of 10 so there's 2 spares there automatically).

                                                                                                                                                 

Connecting rods and their fasteners are one of those most critical elements of any engine, especially one running blown fuel. GRP are one of the go to firms for weapons grade rods these days. These are billet aluminium and designed to withstand the abuse of nitromethane. Typically they'd be rotated out of service after 10-12 passes. In a big show Top Fuel car they'd see 2 or 3 passes - so we get our moneys worth.

On the science side of it, rod breakages vary in nature, but a large percentage come from incorrect torque figures. GRP rods in this application require 90lbs/ft on the bolts, with lube (the science of lube, that's its own story).

The numbers that are associated with the forces exerted on the rods are quite daft (cylinder pressure reaches nearly 13,000psi). At the top of the piston sweep up the bore, the rod wants to break at the parting line and throw itself off the crank journal. It elongates so essentially goes out of round and becomes egg shape - this is where bearing clearances become critical and they have to be large enough to allow this 'pinching' to go on but still ensure oil gets between the surfaces. Rod bolts will stretch to a predefined elastic limit before moving to a plastic state - the purpose of torquing them being to compress them to provide the room to expand whilst keeping the rod together.

A rod bolt stretch gauge is used to check how far gone bolts are. Beyond 0.007" they get junked. Even the expensive bits are consumables and service items .

Chevyonfuel

To get the body straight from front to back and top to bottom, a frame was built around it. One thing I've learnt during this build is when given the option of what gelcoat to have on the body, always go with white.

Black might look nice and sinister, but it stops you being able to add lots of marker pen to it when fabricating various bits to fix under and on it. This is why there's masking tape all over the place...

Onto the fixing...
The rear wing wonkyness and mid length twist was sorted by slicing the body open almost full width and raising the left hand side the 1.5" it required.

                                                                                                                                                 

A a side note, the steel pads you can see in the above photo form the backbone of the various mountings that form a strut onto the chassis. I'll have some detail photos of those once the underbody work kicks off.

                                                                                                                                                 

                                                                                                                                                 

The steel straps are to hold in place for glassing, they'll be removed afterwards and the myriad of holes filled in. The one advantage of fibreglass being that it's easy to repair, if a bit time consuming.

Onto the front end - the depth of the nose across the front of what you'd call the bumper, was a little shallow once the ride height and front wheel clearance were fixed. The fix was to section a new piece in - fortunately unlike the rest of the car, the lines along the front have very little in the way of curves so it was a straightforward job to shutter some plate in for re-glassing.

                                                                                                                                                 

Finally (for now), the roof. The left side of the roof line had a big dip in it - very easily spotted and would have been made worse after paint. There were two options for adjusting it to level it out. Firstly you could cut the A-pillar and splice in a new section of glass at whichever end you cut. Or, you could take a slice through the body meaning the A-pillar itself stays the same length as the opposite side.

                                                                                                                                                 

                                                                                                                                                 

This has taken a while to sort but hopefully it's the hardest part of the build now complete. Once the new bits of fibreglass are in, attention will turn to internal steel treework to sit the body on the chassis in a permanent condition.

More updates in a week or so, and hopefully some engine news...

Chevyonfuel

Prior to a proper update over the Bank Holiday weekend, the latest engine related stuff...

The spare motor and some odds & sods parts will be shipping toward the end of this week. The spare short motor is identical to the first engine with the exception of the crank having standard journals vs the .010 grind on the first engine.

The various studs littered around the bottom end have all manner of different torque specs:
Main studs: 130lbs/ft
Cross bolts: 80lbs/ft
Rods: 90lbs/ft
                                                                                                                                                 
As is the case with most used blocks of this ilk, it's been windowed and isn't overly pretty on the inside of the oil pan rails, but the critical dimensions are all in tolerance and this was the spare bullet for a Nostalgia Top Fuel dragster so it's ready for action immediately.

                                                                                                                                                 
On the cylinder head side, torque specs vary depending on which row of studs. The top row torques to 60lbs, the second row to 140lbs and the third row to 110lbs, in the order of row 2 first, from the inside out, then the top row, then the bottom row. Most obvious here is the top row works in a different fashion - the studs fix the heads and are clamped to the valley side of the block.

                                                                                                                                                 

One complete rack ready to go in the block. This is the same combination of Arias pistons and GRP aluminium rods. The front two cylinders have slightly lower compression than the rest.

                                                                                                                                                 

Other that pushrods, lifters and rocker assembly, here's a complete long block - cylinder heads match those of the first engine. In the event of engine damage (windowing a block for example). It's quicker to change the whole engine, as you cant repair the block at the track and more often than not the piston of the now two-piece rod will have taking a swipe at the combustion chamber of a head and mullered it.

Next week there should be an update on the chassis and body. It's inching forward and the next month should see some decent progress .

Chevyonfuel

The briefest of updates before the weekend...
The body glass work is complete and should be back in the workshop shortly - I haven't seen it for a few weeks so sadly there's no photos to show - I may have an update next weekend on that front.

The 2nd motor and spares package is due to leave LA shortly, that'll be a month or two on the boat, then essentially every bit of hardware will be here and the build becomes a final assembly job for the powertrain side of things.

                                                                                                                                                 

Off to one side from the build, I've got some good support from Lucas Oil, whom I used for most of the lubrication requirements on the last car. Engine oil is 70wt mineral based with additives to counteract fuel dilution caused by nitromethane. The oil left in the pan after a run is still milky and gloopy and needs changing, but it does the job of oiling the motor at a high pressure.

Hopefully I'll have a proper update after next weekend

Chevyonfuel

A quick update following the weekend. There's not a huge amount going on at present, partially because the body is now finished in terms of glass work (piccies to come once it's back in the workshop), but mostly because the big show Funny Car is being prepped for Goodwood this weekend. With the theme being "full throttle - the endless pursuit of power" it makes sense to take an 8000 horsepower Mustang... .

Once that, and Dragstalgia are out of the way, it'll be all hands to the pump to get the Corvette back on track. The National Finals is achievable still, so that's the plan - with possibly the Flame & Thunder as a backup plan just to perform system checks in the pits (it'll be cold, rainy and not great conditions to be testing a new car and rusty driver).

By the end of July, there should be some proper progress and I'll start piecing together the first engine properly. If time allows I'll put some words and pictures together - nothing beats a 426 Hemi fuel motor build .

Chevyonfuel

Ordinarily, no news would be good news… here’s the latest:

The chassis mods have somewhat stalled; there’s a lot of stuff going on at the workshop and outside in terms of fabrication et al so we’ve been pulled away onto other stuff recently (see below). Fabrication should continue in earnest in the next week or so – once Dragstalgia is out of the way with the big show Funny Car. There’s another story all together to cover when it comes to that car, but essentially it goes something like this…

Santa Pod is 50 years old this year. With Dragstalgia (happening this weekend) being a celebration of the sport from back in the day, it made sense to put something together with a bit of history. FGR also happens to be 60 years old this year, and had a pivotal role in building the facility in the early days. Back then, when Funny Cars were cool, one of the pioneers of the sport in this country was Allan ‘Bootsie’ Herridge, a very talented chap who was sadly killed in 1983 while testing a jet dragster. Earlier in the 1980’s, he drove a Trans Am Funny Car called Gladiator. The idea of a tribute came up only a few months ago, so work began to get the FGR Mustang bodied monster freshened up and ready for paint. Here’s the result:

                                                                                                                                                 


                                                                                                                                                 
The original Gladiator - Pic by Jon Spoard, UKDRN.co.uk

As far as a modern take on a period paint scheme, given how different modern cars look in their shape, I quite like it. It’s much cleaner in design than many modern paint schemes. It could be the start of a new trend, we'll see.

Anyway, once this weekend is out of the way, job's a good'un and there should be proper fabrication happening; like I mentioned before, the delays have meant that testing will be delayed til early next year, but at least by then it'll be wearing some paint and be the finished article

Chevyonfuel

Some late Birthday presents arrived yesterday (I didn't get photos of everything, as there's some repetition as some parts have already been seen). In any case, the spare motor in long block form arrived. Identical spec to the other engine with just a different grind on the crank (std/std vs .010/.010). When the time is right, the crank will come out and be ground to make both motors identical - in the first case though I'd only look to this engine to borrow the heads if we damaged one on the first engine.

                                                                                                                                                 

                                                                                                                                                 
along with the diaper that hangs beneath the engine, nestled around the oil pan to catch any shrapnel and oil should there be a leak or the block gets windowed.

                                                                                                                                                 

Being carbon fibre rather than ballistic kevlar, it's far easier to work with - it's very typical to see cars with soft kevlar diapers being cable tied to death in order to ensure the bag doesn't dangle too far below the bottom chassis rail. With the carbon deal, it's just a case of hooking it on to the clips & straps that wrap around the top frame rail, and raising it til it's snug with the oil pan.

The other advantage of carbon fibre - it just looks damn nice

The rest of the day was spent sorting out cockpit geometry. Apologies for the lack of photos, I had my legs in the air (literally) so couldn't take any informative snap shots of the yoga positions I was learning whilst pedals were moved.

The crux of the issue is that with the seat moving down, rotating and moved forwards nearly 200mm, the natural location of your legs (mainly the right leg for the throttle) now has nowhere to sit as it's jammed between the chassis rails and the transmission, and you cant fit a pedal in there. The solution is to raise the pedal location above the gearbox. In this case, the seating position leaves my right knee almost in line with my shoulders. This is quite extreme and more akin to what you'd see in F1 where pedal boxes are mounted above the driver's backside to elevate their legs.

No doubt this sounds very lacklustre from an ergonomics perspective, but it was commonplace in the 1970's in the original cars that suffered the same practicalities when moving the driver down and forward. The result was knees visible through the side windows. We're in that same boat...so you could say it's starting to resemble a proper 70's Funny Car.

It's not overly comfortable, but it's workable - I'll just need to do some stretches before getting strapped in. The cockpit mods should be complete in a matter of weeks, so it'll be onto the front end mods, rear tree and body mounting by around September .

Chevyonfuel

There’s some proper updates coming after this weekend, but to keep things ticking over – an example of one of the ‘snags’ encountered in recent days. The transmission…

                                                                                                                                                 

Lenco produce the finest drag racing transmissions, the CS1N being the daddy when it comes to nostalgia nitro applications. Compared with the CS1 it has a slightly larger case and contains beefed up internals, and as a result has less options for gear sets. The plan with the CS1N I have was to put a different low gear in it (currently 19% reduction). The aim was to use a 38-41% reduction. However, the CS1N will only take a 25% reduction. Given the cost of gear sets ($1400) it’s a false economy to spend that much to gain you not a lot of transmission reduction.

The hot ticket in Nostalgia Funny Car is actually a 19% Lenco, but with a 4.29:1 rear end gear. This however requires a lot of torque in low gear to achieve sub 1.0 60ft times, and a lot of strength in the valvetrain at the top end; you’ll be touching North of 10,000rpm going through the top end. I’m happy that it would be achievable, but that’s for another day when the car’s gone down the track without incident. There’s no prizes for zinging a non-proven combination to the dizzy rpm heights mentioned, just yet.

The baseline setup for the Corvette will use the 19% low gear, with a 4.11:1 rear gear. Some quick maths suggests circa 9200rpm at a terminal speed of 240mph. That’ll work nicely initially, and avoids the necessity to rebuild rocker arms every other meeting, and replace valve springs and potentially connecting rods more frequently than. The 4.11:1 rear gear has been ordered and should be here in a month or so. 60fts in the 1.0 zone shouldn't be a problem, but we wont be having any 0.9's without murdering the clutch routinely.

The Lenco will be getting stripped and inspected possibly before Christmas, so I’ll try and get some photos of the inner guts of the thing - there’s a lot of stuff that goes into them. For something with such simplicity in its operation, it’s certainly a pain to piece together (regular CS1 assembly diagram below).

                                                                                                                                                 
In other news… the body is having its internal ribs glassed in. These work much like an actual rib cage, providing some skeletal strength without excess weight. There’s no firm date for when the body will be married to the chassis, perhaps a month or so – it’s seat fitment day this coming Saturday. Easter is looking a certainty, albeit without paint on the body. This is partly down to money, and also down to thinking a little further forward. The body will settle down on its mounts after it’s had some downforce applied to it. Any adjustments or tension cracks can be remedied before paint is applied.

More news (and piccies) after the weekend hopefully .

rousetafarian

The depth of detail in this thread is astonshing, and also very well written.

Facscinating stuff!