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

RBZ5416

Love the bark of a nitro-fueled v-twin.

Chevyonfuel

Proof that everything is made better by the addition of nitromethane...

I'd quite like a nostalgia A-Fuel car one day; they're quite cool. Nothing sounds like an A-Fuel motor, injected nitromethane, no blower - high compression -  they sound like a shop full of uzi SMG's being fired simultaneously .

This afternoon I had a small project on the go to keep things ticking along. I'll grab myself a cuppa and get typing...

Chevyonfuel

This afternoon was a small success, or at least some jobs ticked off the list.

Firstly, to explain the setback manifold and retro blower deal...

                                                                                                                                               

Ordinarily, supercharger bottom openings are full depth and width. There's nothing particularly wrong with this but it's an old design and the legacy of Detroit diesel blowers on which the current race blowers are based. The blower above is a basic 6/71 street / hot rod blower, standard location and standard opening.

The idea behind a retro opening is to help channel the air and fuel mixture into the manifold with slightly more precision, and if you shift the location of the blower on the manifold, you can pinpoint the best place to be cramming this fuel and air mixture in to give each cylinder the best chance of being fed properly.

                                                                                                                                               

The business end of the blower is slightly different to the one above, a delta shape opening which crams the fuel air mixture out through the front end of the casing. The blower is set back on the manifold for the reasons noted above.

The setback plate is nothing more than an adapter that allows you to fit a retro blower onto a standard location manifold by way of countersinking the fixing holes and adding a second set further back (1" or 2" are typical in terms of the change).

A receiver groove is cut into the plate to allow an o-ring to slot in between the set back plate and bottom blower restraint plate. This needed a thorough clean to remove the debris of the last o-ring and sealant that had been used. I'm still waiting on some parts to finish the manifold work, but it was a good opportunity to offer up the new o-ring to check it was a good fit.

                                                                                                                                               

                                                                                                                                               

                                                                                                                                               

The blower assembly, particularly on the top side, is nowhere near as simple as you'd expect. Gaskets, plates, more gaskets and finally the injector. To explain the machined spacer sat on top of the blower, it's to assist in raising boost by getting the injector up into clean air above the top pulley, and some machine work on the front end allows air to accelerate into the blower inlet (a kind of ram air system).

                                                                                                                                               

The assembly sequence requires a gasket on top of said inlet, followed by the top blower restraint bracket, then another gasket...and then the injector. With that all done and tightened up, it was time to plumb the last of the injectors.

                                                                                                                                               

In this application, the rear most fuel injector nozzles are plumbed into the rear of the blower case. The primary reason for this which I might have mentioned before, is to cool the blower rotors, and since the air and fuel mixture is thrown to the front of the casing, this lowering in temperature gains you some more power.

                                                                                                                                               

                                                                                                                                               

One last minute alteration - the intake gaskets needed some trimming. Ordinarily the blower would have a cross member in the casing where the gasket crosses transversely (shown still present above). Not so in this instance so some quick cuts following the above photos got rid of gasket material that would be flapping around in the breeze.

                                                                                                                                               

                                                                                                                                               

The restraint system is a mass of brackets, plates and straps - the additions to what you see here will be the bottom plate that'll sit on the manifold, and the bag that sits around the blower. All the black straps which flap about end up just being just folded into the bag out of the way.

Other than some small parts including the throttle cable bracket and return spring, the top end just needs marrying to the manifold and job's a good'un. That might be a job during the week one evening if time allows.

On the chassis front, the chassis is due to be off the jig in a few days, the rear tree is finished - no photos at present, I'll try and sort some shortly .

Chevyonfuel

This morning the annual tech inspection for SFI certified parts took place - the clutch and bellhousing being inspected in my case. Everything with given a clean bill of health (as expected, they've not been used since the last inspection).

Back at the workshop, the chassis came off the jig, the rear wheels were dropped on to help confirm the ride height of the body in a couple of days. The immediately apparent observation this morning was how low the car was. If you ignore the fact the front end isn't connected - the rear and roll cage area is now low...very low (this is good).

                                                                                                                                                 

                                                                                                                                                 

                                                                                                                                                 

The rear tree is complete bar for the oil catch can being dropped in, and the fresh air system for the cockpit being added. The Co2 bottle for the airshifter is being remounted at the front of the car to simplify the plumbing a little. The fire bottles are now a bit easier to access, maintain and remove.

                                                                                                                                                 

                                                                                                                                                 

The tree itself is quite well engineered; for something so seemingly simple, there's a lot of stuff going on. Most trees have a mass of tubes in all directions to cater for fixing of fire bottles, catch cans etc - they get quite congested and become tricky to work on. This approach should yield benefits long term.

In a couple of weeks the body will be on the car properly and we should be able to wheel it outside for some proper photos .

Back to the motor...
I spent last night assembling the top of the injection system for the last time. As mentioned before...gaskets...o-rings...some more gaskets.

                                                                                                                                                 

The blower manifold studs from ARP are designed to have their threads give up if the blower decides to make a break for freedom. It makes them a bit of a consumable but it's cheaper than replacing the blower as regular studs would probably cause the casing to fracture in the event of it trying to launch the blower off the manifold.

                                                                                                                                                 

The bottom restraint plate is simple enough, this sits on the o-ring surrounding the intake side of the manifold.

                                                                                                                                                 
Finally the blower bag which wraps around the casing and is strapped in above and below it. That's everything done with the exception of mounting the throttle cable bracket (later this week when some bolts arrive) and the throttle return spring to ensure the butterflies close when the throttle's shut.

More piccies in a few weeks .

Chevyonfuel

Some quick snaps of the latest bits nearing completion. The titanium head shield surrounding the roll cage is a carry over from the previous cage, with some slight amendments. After dropping the cage a long way, they needed some refinement to fit neatly. As much as titanium is a wonderful material, it's a pig to work with and you'll murder a cutting disc each time you make a cut.

                                                                                                                                                 

                                                                                                                                                 

These shields became mandated a few years ago after it became clear a lot of head injuries were being caused by debris from tyre explosions and the like entering through the rear of the cage.

In a couple of weeks we're hoping to have the chassis rolling around, at which point the body will be back on and ready for the internal tree and tin work fabrication. Proper piccies to follow

Chevyonfuel

A quick update prior to Easter (new stuff arrived).

This is the clutch pedal - there's nothing overly special about it as the use isn't much different to a road car albeit the clutch itself being centrifugal, you don't have to worry about slipping it like you would a regular clutch. In this application it's just used to reduce the heat build up in the clutch as it tries to engage under centrifugal force at idle.

                                                                                                                                               

Like most things, it's fabricated from chromoly steel. It'll be attached to either the bellhousing or frame rails, and the linkage then attached to the candlestick which controls the throwout bearing inside the bellhousing.

                                                                                                                                                 

The remarkable thing with this is the timeframe. I took the decision to get it fabricated by S&W Racecars who also produced the oil catch can (a while ago) because with it being what you might deem a catalogue item, the production costs are lower. From ordering it to delivery was 6 days. A 3400 mile trip, and bear in mind they're fabricated to order rather than just sat in stock waiting to ship. Quite good service really .

With the cage work now almost complete, attention turns to the front end of the chassis. If you remember a long way back, the top and bottom tubes were cut to allow the body to clear the front (previously the fuel tank dangled a long long in front of the axle centreline).

Some fettling and tidying needs doing before the tank can be relocated and a pocket cut out to clear the frame rails in that area. Piccies soon .

Chevyonfuel

The moment of truth...did the body fit nicely with all that faffy fabrication done...

                                                                                                                                                 

                                                                                                                                                 

                                                                                                                                                 

                                                                                                                                                 

Given the constraints of the chassis and the re-engineering it had undergone to make any of this possible, I think we did alright. The ride height, wheel arch heights and overall stance are close enough to qualify as period correct. The only way of improving it would be to build a new chassis, with a wider axle. That isn't an option on the table, so it's good news that the roll cage lowering, axle lowering etc all worked out.

Later this week the chassis chemical blacking will be started. This is interesting stuff and hopefully I'll get a chance to go through it in the next update (Sunday, perhaps).

Chevyonfuel

Apologies for the lack of updates, it's been mental busy recently in the real world. I also (as you can see above) have run into some issues with photobucket, so have the nice task of porting over everything to Flickr when time allows. Fun times...

Onwards - chemical blacking. With bare chromoly tubing, it quickly becomes susceptible to surface rust and dulling in colour. Rather than painting it, chemical blacking is a very efficient and cost effective way of producing a uniform, corrosion resistant finish. It started out life as a military system that filtered its way down into consumer applications (following use by gunsmiths and the like).

As things progress I'll hopefully have a before and after comparison. We'll start with the 'before' look. To ensure a nice finish, you need a nice basis. That meant scrubbing the steel back to a clean, smooth finish. With the amount of tubing and angles of dangle, it's time consuming, as well as requiring the rear axle to drop out of the chassis.

                                                                                                                                               

                                                                                                                                               

                                                                                                                                               

In a couple of days the blacking treatment should be applied and sealed (a mixture of de-watering oil and ACF-50). The advantage with chemical blacking is it can be done at room temperature, by hand, it doesn't need to be bath dipped etc. In addition, it can be welded to - you simply re-black the new pieces afterwards.

In other news, the body is back off the chassis now the internal tree assembly is fabricated and welded into place. I'll get some nice photos of this because it's one of those most complex areas of the build that will never get seen when the car's on track.

The plan is to crack on with the Flickr move later in the week (hopefully) and a proper update on Sunday when I'm back from the workshop.

Chevyonfuel

Hopefully the chassis wont end up in this orientation in later life, but it was necessary to clean everywhere - it's probably the cleanest and nicest it's ever looked since it was first fabricated.

                                                                                                                                                 

                                                                                                                                                 

The blacking treatment should start today; frustratingly we missed the boat on the weather front. While it's a room temperature exercise, they recommend warmer conditions, so we're about a week late to the party - no matter, with the space heater on it'll soon be toasty enough to get the job done while it chucks it down outside.

Chevyonfuel

So the first part of the blacking went on earlier today. For some strange reason it's panning out differently to the last chassis the stuff was used on. It's ordinarily meant to coat the steel and give a satin grey-black gun metal finish. Much to our surprise, the chromoly has come up looking like heat treated stainless steel (think exhaust headers after a few heat cycles, a mixture of blue tinges, light spots and dark spots). It's a bit odd, but seems to work, and looks quite smart in a twisted way.

                                                                                                                                               

Some extra coats tomorrow will confirm if it's just a layering thing or a result of the treatment simply reacting with the steel in a way that leaves that kind of finish. The process is quite specific:

Degrease steel --> chemical black treatment --> fresh water wash clean --> de-watering oil seal.

Hopefully some more photos same time tomorrow - in conclusion it's different to what we expected, but no less effective (remembering it's just a corrosion treatment and doesn't affect material thickness or flexibility of the steel). Funky stuff