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

Chevyonfuel

Well-known Member
Rather than spamming the modified car thread, it’s probably better to lump this in its own thread…

So – after racing in Fuel Altered for a couple of years (see here), and messing around with a Nostalgia Top Fuel car prior to that, I took a few years out to recoup some of the money that was pissed down the toilet. A slight diversion back into AV meant plans changed and the return to racing was delayed. Finally I’m slowly getting back on programme, and the new race car is ever so slowly taking shape.

I’ll update this thread as things progress. Here we go…

Nostalgia Nitro Funny Car (what the f*** is that?) – warning…history lesson drivel…

In the last 15 years or so, drag racing has become financially crippling at the higher levels. As performance levels increased, as did costs. These days a big show spec Top Fuel car uses a fuel pump that flows 120 gallons per minute, a couple of 44 amp magnetos and a mutts nuts supercharger in order to make 8 - 10,000 horsepower. Bearing in mind that modern Top Fuel & Funny Car only race to 990ft these days (a safety issue after a fatality a few years ago, and the terminal speeds surpassing 335mph over the standing 1/4 mile), the cost of a run, without accounting for any damage, is around $8-10k. Destroying an engine is all too easy, and at $50-100k a piece, it soon becomes pricey.


Modern Nitro Funny Car (supposedly a Mustang...)


Nostalgia Nitro Funny Car (Plymouth Arrow & Chevrolet Camaro)

In the same way as most motorsports, the look of cars has become a little generic in recent years. Aerodynamics, efficiency and corporate sponsorship all had a part in taking away the fun and the identity from race cars. Back in the 1970’s, cars more closely resembled their road going counterparts. For most, it was the golden era for the sport. This, along with the cost implications mentioned above, meant a plan was hatched to build a nostalgia class, that recreated cars of that era, but with modern safety kit, and rules that were sympathetic to the engine technology of the period. What resulted was a class where Funny Cars look like they used to, but go quicker than the period they portray. Fuel pumps are limited to a flow of 21 gallons per minute, superchargers are limited to a 6/71 GMC style unit, driven at a maximum 18.99% overdrive. Cubic capacity is limited to 500 cubic inches.

The cars run on a blend of nitromethane and methanol. Nitromethane isn’t to be confused with nitrous oxide. As exotic fuels go, nitromethane is in its own league, and technically deemed a chemical rather than a fuel. Due to oxygen content within the fuel, less air is required to burn it, meaning 8.7 times more nitromethane can be burnt in one stroke. It’s also a high explosive, featuring more high explosive energy than TNT. The result of all this when injected into a combustion engine, is circa 3000-3500 horsepower in a rule restricted application such as this. The by-product of burning nitromethane is nitric acid vapour, hence why we wear gas masks during engine warm-ups.

As a rough guide to the ¼ mile performance figures; Elapsed times in the 5.7 – 6.0 second range, at terminal speeds of 240-260mph are expected.

Onto the car build…

The foundation of the car is a 426 Chrysler Hemi block, with its design roots dating back to the 1960’s. Rules stipulate that cylinder heads have to retain OEM architecture, so whilst the basic design cannot really deviate, the materials used, certainly can. The block is billet aluminium made by TFX, as will be the heads & crankshaft. As the rules limit the fuel pump size (21gpm @ 4k RPM) in order to maximise the volume available, it’s common to use a small capacity, higher revving engine combination. In this case, a sub 400ci build, that will rev North of 8k RPM. If the engine's turning at over 8000rpm, the cam driven fuel pump is spinning at more than 4000, hence more flow. Simples!



The maintenance regime for this combination requires the engine to be stripped down to the block after a run (pistons out, rods out etc), oil changed, spark plugs changed, possibly some rod bearings changed, and then re-assembled and fired up for the next run, in around 2 hours. This is regardless of damage incurred, as everything needs a thorough check, as everything works loose on a run, and minor damage is expected (you’ll often find aluminium shards in the oil pan regardless of doing no actual damage).

In the case of melted pistons or scuffed bores, the liners can be swapped out quickly (with some blow torch assistance).



The chassis is of chromoly steel construction, to SFI 10.5 (one step up from the required 10.1E). The chassis itself is identical to a current Nitro Funny Car chassis, the only differences being the tyre diameter and rear end gear ratio. Modern cars run a 36” tyre (17” wide) and 3.20:1 rear gear (direct drive, no transmission). Nostalgia cars run a 34.5” tyre and nothing lower than a 3.89:1 gear and a 2 speed transmission.

Bodies can be fibreglass or carbon fibre. To be honest, fibreglass R&D has progressed that much that the weight saving by using carbon fibre isn’t worth the extra outlay financially. In addition, bouncing it off the wall at North of 200mph, it’s cheaper and easier to repair glass than carbon.

I'll post some more photos when things get underway properly. At present the body is still in Philadelphia, the motor is in San Jose and the chassis is in Essex, logistical nightmare :confused:...
 
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RBZ5416

Distinguished Member
Look forward to reading more on the progress.

Really need to get my backside back up to the Pod. It's been far too long since I drove home with nitro fumes in my nostrils, tyre smoke in my hair & a big grin...
 

rousetafarian

Moderator
This is fascinating thank you for taking the time to post!

I have one simple question, what the hell does it feel like accelerating with such force it must be difficult to comprehend until you have experienced it.
 

Chevyonfuel

Well-known Member
Look forward to reading more on the progress.

Really need to get my backside back up to the Pod. It's been far too long since I drove home with nitro fumes in my nostrils, tyre smoke in my hair & a big grin...
There's the Flame & Thunder event in a couple of weeks, though IMO the weather's turned so it might be a washout, we were spoilt in September, so the weather needs to balance its books somehow :). That'll be it for the year then, resuming next Easter.
 

Chevyonfuel

Well-known Member
This is fascinating thank you for taking the time to post!

I have one simple question, what the hell does it feel like accelerating with such force it must be difficult to comprehend until you have experienced it.
No problem at all :thumbsup:

The two seater experience that Crocodile mentioned is a good window into the quick cars (7.9 @ ~169mph generally) - not the cheapest 7 seconds of your life though:D.

What I found in terms of how acceleration felt, was that launches feel quite sedate until you get into the low 1.1 second zone to 60ft. Shorter wheelbase cars like Altereds and Funny Cars become a different animal when they launch a tenth or so harder. Most quick cars have toe loops on their throttle pedals to help keep your foot on the pedal as they'd be pushed off it otherwise.

Often you'd find that methanol burning cars will get to the 1/8th mile every bit as quickly as their nitro equivalents, but they run out of steam and don't put on big mph in the 2nd 1/8th. A nitro car is just getting into its stride by then, as the clutch should be fully locked in and full power delivered to the rear wheels.

Deceleration tends to be where the most G-Force is applied though. It's something like minus 5G when the chutes blossom, which gets your attention, mostly because it tends to get the rear of the car airborne briefly. It's been known to cause injuries in modern Top Fuel dragster, when harnesses haven't been done up tightly enough and the hit of the chutes causes broken ribs for drivers.

The only damage I ever did relating to chutes was on my licensing run when I was a bit late on the chutes, having had a face full of oil and couldn't see where I was going. I'd run 209mph, but was at closer to 220 when I finally got the chutes out. The shutdown area was quite bumpy and it launched the car into the air. When it came back down, it cracked the body and a couple of chassis uprights tried to punch their way through the bottom tubing. The tubes were sorted and gaffa tape took care of the cracks in the body :D.
 

RBZ5416

Distinguished Member
There's the Flame & Thunder event in a couple of weeks,
I've spent far too many cold/wet/both days on the muddy banking at the Pod for firework specials. You can't even huddle together in the warm glow of an afterburner in the barn any more!
 

Chevyonfuel

Well-known Member
Quick update: Not a lot to report, the short block assembly is progressing. The custom grind camshaft being dialed in after the gear drive and associated bits arrived.



Next up will be the simple assembly for the rest of the block, which is then buttoned up over the winter, as I'll be switching focus to getting the chassis together in Q1/Q1 next year. Engine wise the next thing will be getting the cylinder heads and valve train together, which is relatively straightforward, but prohibitively expensive :facepalm:.
 
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Ed Selley

AVF Reviewer
Is that a new 426 block or is the basis for this (barely) controlled explosion a forty five year old elephant engine? I'm also intrigued if any of the qualities that make the 426 a great engine on conventional fuel translate under these rather more extreme ones- ie is the 426 better than the Chrysler 440 of the same period (or Ford 429 or GM 454) or are there just more bits for the 426?
 

domtheone

Distinguished Member
Kind of knew the 2 seater thing would be costly but, i clicked on the link anyway thinking it it was anywhere close to £200 ish, i'd be 100% up for that.

£400 though for a sub 10 second ride:eek: Aye Karumba.

I'll think in it for a year or so:D
 

Chevyonfuel

Well-known Member
Is that a new 426 block or is the basis for this (barely) controlled explosion a forty five year old elephant engine? I'm also intrigued if any of the qualities that make the 426 a great engine on conventional fuel translate under these rather more extreme ones- ie is the 426 better than the Chrysler 440 of the same period (or Ford 429 or GM 454) or are there just more bits for the 426?
The block in question is a new(ish) billet aluminium block by TFX. The fundamental architecture is that of a 426 block. In terms of actual improvements in design, physically there's not a lot of differences bar some extra ribs in the lifter valley, cross bolted main caps and use of materials that just didn't exist back then (aerospace grade fasteners and the like). Some OEM parts may fit, but a lot of the provision for ancillary parts are removed as they just aren't needed (alternator as an example).

The 426 itself was a winner due to its cylinder head design i.e. hemispherical rather than the typical wedge or heart shape. The ability to burn much more fuel was the primary reason it was adopted for running methanol and nitromethane - it's pretty much a case of 'burn more fuel, make more power'. In the same way, it was the daddy in the other racing disciplines such as NASCAR, and the Chevy motors had no response. Oddly enough, the Chevy blocks were immensely strong, and in aftermarket form, have more cross bolted main caps than a Hemi block does. Chevy and Ford motors just cant breathe that well, so they lost out in the end to the Hemi, which just works perfectly for fuel racing.

In the same way that the 354/392 Hemi became a 417 Donovan (the first race bred aluminium block), the same happened with the 426 when Keith Black started to produce aluminium race blocks. Aside from the lack of water jackets, the race blocks such as this one had critical fixings moved for ease of maintenance between runs, since we'd tear it down to a bare block for inspection purposes and have it ready to fire up within an hour and a half - so whilst you cant really move cylinder head studs, other studs such as manifold ones are located in a way that only 6 are required and the blower / manifold assembly can be off the car within a few seconds.

At present, the billet block I'm using would be classed as state of the art in so much as it's used by NHRA teams in big show fuel racing - there hasn't been anything anything revolutionary in recent years, it's just evolved over time (small things like moving of oil galleries in the lower area of the block to make weld repairs easier when it gets windowed (which they do, often) were realised back in the early 90's. More recently there's been a move towards bigger diameter cams, meaning raised cam tunnels to clear the crank, resulting in various options in terms of block deck height.

Here's the result when it comes to between rounds maintenance - considering F1 teams are praised for changing an engine in a couple of hours... :rotfl:

 
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Chevyonfuel

Well-known Member
Quick update:

The short block is finished and largely buttoned up for the time being.


There’s a couple of bolt-on bits to add, namely the bottom pulley, idler pulley assembly, oil pump & removable filter assembly.


Dry sump oil pump & filter

The filter unscrews for ease of maintenance. Due to nitromethane being such a wonderful fuel, it eats parts, so you’ll often find fine shrapnel in the oil pan after each run, even if it hasn’t lunched a rod or piston. This combined with the reaction between the fuel and oil, mean oil changes after each run are required. The fuel that bypasses the rings, mixes with the oil and essentially turns it into the automotive equivalent of cauliflower cheese. Using an oil stabiliser can help, but it’s a false economy to try and run the same oil again, so it gets a change for every run.

The dry sump pan has seen some life, but will go again and the weld job makes it perfectly usable. As nice as it is to have brand spanking new bits, the ugly looking parts still work; eventually a full beans spare motor will be built, but it’s less financially depressing to hurt pre-loved bits whilst ironing out the bugs and getting a safe, workable tune-up dialled in.



That’s about it for the year. In January the pricey bits will become the focus, namely the cylinder heads, rocker assembly, supercharger and fuel system components. I'm quite far behind my own timetable for the build as a whole, but we carry on regardless... :thumbsup:
 
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Chevyonfuel

Well-known Member
A quick update following Christmas and New Year. It's been a quiet period for myself, real life got in the way of fun stuff, but here's where the build is at the moment.

Just before Christmas, the idler assembly and bottom pulley were mated to the block. That completed the short block, meaning it was time to move on to the top end, where things get a bit fancy.


These are early BAE (Brad Anderson Enterprises) billet heads. They're a good choice for this application due to the smaller intake ports and valves. Whilst the current iteration of the heads often come up in classifieds a bit cheaper, they're not the best solution for a small fuel pump, small supercharger combination. I'd previously looked at running updated versions produced by Alan Johnson Performance Engineering, but these Brad's were too good a deal to pass up. The valvetrain; rocker stands, shafts and rocker arms have the advantage of being manufactured by BAE also, so fitment and geometry stands a chance of not being...wonky :rotfl:.


The intake manifold is a magnesium item produced by Keith Black Racing Engines. The distribution block and hoses handle the port nozzle fuel requirements. At idle the engine will only take fuel from the injector hat, which equates to around 1.5-2 gallons per minute flow, at around 100psi. The port nozzles come into play under throttle, where fuel pressure rises to just over 300psi, and then the twin nozzles per cylinder play their role (24 nozzles total). There are many ways of distributing fuel in terms of the % that goes through the blower, and that which gets injected via the port nozzles. It gets quite secretive beyond the number of jets as we all have different cubic capacities, cam profiles and compression ratios.

Lastly, the valve covers - these were a nice find as magnesium single plug covers are becoming quite rare. The slotted hole in each is for burn down breathers that help evacuate excess oil, especially in the event of a malfunction. They simply pipe into the top rails of the chassis, and into a puke tank at the rear of the car.

The next things to sort will be the valve train, and then it's onto the blower and fuel injection bits to finish off the motor :thumbsup:
 
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RBZ5416

Distinguished Member
When are you hoping to be race ready?

How do you go about testing before then? I'm assuming you can't rock up to a RWYB with a Fuel motor & burnouts in the local cul-de-sac are probably out of the question! Although saying that, I remember Roz Prior bringing her TF to my local Ford dealer, as part of her Motorcraft sponsorship. Tried a burnout on the dealer's forecourt & it didn't end well. Can't imagine what health & safety would make of that now...
 

Chevyonfuel

Well-known Member
When are you hoping to be race ready?

How do you go about testing before then? I'm assuming you can't rock up to a RWYB with a Fuel motor & burnouts in the local cul-de-sac are probably out of the question! Although saying that, I remember Roz Prior bringing her TF to my local Ford dealer, as part of her Motorcraft sponsorship. Tried a burnout on the dealer's forecourt & it didn't end well. Can't imagine what health & safety would make of that now...
I'd hoped to be ready for the start of 2016, but funds and some other issues mean it's looking more like the end of next year now, I'll keep pecking away at it though - it's more a money than time thing, as a chassis build will only take 8-10 weeks with all the ancillary bits available.

Most of the bigger events have a weekend test & tune event prior. There's the odd mid season test event also. You could appear at a RWYB as long as you gave the track enough notice so they can get their safety guys to bring their full firesuit (they don't have to worry about Saxo's and Fiesta ST's getting BBQ'd, generally :D). However, it's unlikely they'd prep the track for just one fuel car. A RWYB would be sledded and prepped for street cars, but it wouldn't be glued - it's too expensive for the limited number of race cars that have only paid their £20 for the day, and for the lesser powered cars, the glue often causes issues like broken diffs and half shafts... :rotfl:
 

bobflunkit

Well-known Member
Loving this thread. Motor looks like a piece of art. I'd be keeping it in my living room, just to stare at.
 

Chevyonfuel

Well-known Member
April update…

The cylinder heads will shortly be returning from the machine shop – the heads previously saw duty fitted to a cast Keith Black block with ½” head studs. The more modern TFX blocks use 9/16” studs so some work was needed to open up the stud bores (only by a knats). The valvetrain assembly is run of the mill race spec Hemi stuff – shaft mounted rocker stands, shafts and heavy duty rocker arms. Spring pressures are circa 350lbs static and just over 1000lbs at peak (not at high as some weapons grade methanol burning engines but sufficient in this application).

Onto the supercharger – it’s nothing exotic, just a standard race spec billet rotor 6/71 roots unit with teflon and nylatron striping on the rotor tips.



Due to the inlet being a predefined size, the fuel distribution in the traditional layout isn't optimal (4 injectors each side of the injector hat, feeding into the top of the blower). The 3 holes towards the rear of the blower case provide the option to inject some fuel to the rear end of the blower casing (in this case, a pair of jets, one each side of the casing). Due to the nature of roots blowers making a lot of heat and becoming quite inefficient at higher overdrive, the fuel that can get to the back of the blower, helps cool the intake charge and keep temperature down.

As we're limited to a specific supercharger size, rotor type and overdrive (18.99% max OD), the only option available to make a difference is to make boost at as low an overdrive as you can. Less heat production equates to cooler intake charge and more power. Simply upping the overdrive only works to a point. The holy grail of modern nostalgia blowers (slight irony in terms there) is a billet case, billet rotor'd design with some CFD developed innards. These however sit at around the $6-7.5k mark versus my little blue BDS at $3k. They make serious amounts of boost (33psi at the hit of the throttle), but mean some clever tinkering is required in the fuel system to make air fuel ratios workable. For the time being, this should do the trick.



As per most race grade blowers, this one features a delta bottom opening, discharging to the front of the case. In recent years, to assist in equalizing the manifold pressure to all cylinders, setback manifolds which physically locate the blower further back on the manifold, have been common (the trade-off being needing to use a longer snout between the blower and top pulley).

More photos and waffle in a few weeks when the heads should be installed and work starts on piecing together the fuel system.
 
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Chevyonfuel

Well-known Member
Quick update, a mock-up for the motor as is - the blower might still change, and the barrel valve for the injector needs swapping out for a k-valve, but it's getting there slowly.



The list of to do bits for the engine reduces every few months, most of the big hardware's nearly done, next up will be the fuel system and ignition system. :thumbsup:
 
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rousetafarian

Moderator
I am not sure what the hell I'm looking at but I like it, I like it a lot!
 

RBZ5416

Distinguished Member
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

Well-known Member
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! :)
I could pinch the tagline from Birdman... The virtue of ignorance... :rotfl:
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... :D
 

Chevyonfuel

Well-known Member
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.
 
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Chevyonfuel

Well-known Member
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.
 
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