Twin turbo Jag V12 mid engined scratch built Zonda

[nicktruman]

GIRF said:

I am going to assume that you posted this in hopes of getting feedback and assistance in the areas that you are not versed in as opposed to a bunch of "atta boy" and "cool project". So do not take this as a flame but a desire to help.

You really owe it to yourself to do this right. Have you given any thought to your suspension geometry. Have you calculated your roll center or instantaneous center. What is your king pin inclination and scrub radius. I understand that you modeled the A arms on your Ferrari. A bit dated but a good place to start. Still you used Scorpio hubs. What is the KPI on those as opposed to the Ferrari. Did you account for that in either arm length or mounting points. How does the Ferrari's track and cg compare to yours. How much caster and camber have you designed in. You can't just fall back on "I don't know, this is the first time I have done something like this." History is resplendent with trail blazers and mavericks such as you but generally when a person does not know how to do something they learn (study, research) or ask. I did not even ask about your steering geometry.

I don't suggest that you aspire to produce a race winner. But you risk a car that will suffer such camber changes throughout the suspensions travel that it will be undrivable.

Don't take this the wrong way. I would never come here and suggest your body work is bad (a thousand hours of work and a ton of bondo will fix that) or your lights are wrong or anything else that is subjective. You are doing what every car nut dreams of and you deserve huge props for having the fortitude to get started. But I really think you should plan and learn before welding and slathering.

This site www.dpcars.net might give you some insight into how much goes into a scratch built car. Dennis is famous on the web for his car. BTW his car buck/mold was machine on a half million dollar CNC and he still had hundreds of hours of work sanding and filling to do on the plug. Just go to the PAST section and review his 4 year Design and Build logs and learn moree about car design then you ever thought you needed. It starts with a sketch on a napkin.

As mentioned before there are some suspension modeling sw out there. Or you can make your own analog. Finally here are a few books you really should check out:

Allan Staniforth “Competition car suspension design, construction, tuning”
Carol Smith “Engineer to win”
Milliken & Milliken “Race car vehicle dynamics”
Herb Adams “Chassis Engineering” (He gives a step by step that is a great place to start)

I have thought of the geometry, and run the current setup through some software. Based on the assumed weight of the front the result was awful. The kingpin angle is dictated (as you know) by the Scorpio's design. However the camber/caster will need to be reworked.
The front suspension sucks! The top wishbone hangs off the chassis way too low and as a result when the car is jacked up the wheels toe in like crazy! So I have a LOAD of work to do there. By pure luck, the rear suspension worked out beautifully, but then this was one place that i could model (albeit roughly) on the available rear chassis photos of the C12.
I have not at this moment set the front geometry to anything specific and it all needs to be dismantled when I am in a position to move the car (when the body is more portable.
Rightly or wrongly I wanted to set a ride height first, then add a body, this dictates the weight of the front/back of the car and the spring loads/adjustment. I thought (again maybe wrongly) determining the final setup would be a mistake before now.

Kr

Nick

[nicktruman]

I should also add the reason I have put the details/photos of my project on this forum is because I was asked by a number of people.

I am not wanting oohs and ahs I know I have a load of work to do, the idea was to make a car purely from scrap available off eBay for as little as possible. To make a £500k car for £500 (OK up to £2k now ) From the CarPC to the Megasquirt everything has been hand made/built from scratch.

For me the challenge was to take a 1970s V12, mate it to a transaxle which involved machining flywheels, clutches, spigot bearings etc.. then bringing it all to life, making it change gear using powerboat steering cables, rebuilding a couple of tired Nissan 200 turbos plumbing them in, calculating the fuel tables and associated settings etc.. this to me was the challenge.

The car will have scissor doors this is so i can get in/out when its in my garage! The front narrower than the OEM so I can open my internal garage door. This car is about building something completely from scratch that no one has ever done before. I guess that's why I was asked to post its "blog" on here.

Cheers
Nick

[nicktruman]

GIRF said:

Thats cool. Good deal to not lock in the front suspension. It would be really great if you can get a bit of seat time to confirm what the sw tells you. Then you can adjust from there.

Thanks for not taking my post as a crticism.

No worries, i know I need help so any and all (constructive) help is really sincerely appreciated.
tbh the only reason I went for the Zonda shape was because i thought it would be easier to make than a more "curvy" sports car, i.e lots of flat panels.

Cheers
Nick

[nicktruman]

Thanks everyone.
Yesterday I drove the car out of the garage for the first time in months. Pulled out all the polystyrene rear section and thought I would have an easyday enjoying my rather hard two weeks graft.
I put a gallon of juice in the tanks and started the beast, 1st time it started! Drove the car out, let it get hot and ran for 10 minutes, everything working OK.
Turned it off and started cleaning the GRP moldings. Then went to put it back in the garage and nothing, tottaly dead
I pulled out one bank of plugs and it started, put then back - nothing. All the plugs had a huge spark and fuel. I damned if I can see what's wrong

[nicktruman]

Dave Dax builder said:

Hi Nick.
I have been following your thread , and had a look through your gallery pictures. I can appreciate the effort you have put in, done similar things myself....When I had more time.
A couple of things I have spotted (And I really hope you don't mind, though this could be more hurtful that the suspension geometry post above (If you hadn't already done your homework on that one)).
1. A Transit drag link as a top ball joint is over stressed when fitted to a Lotus 7 replica, you will be putting a lot more through one in this application. I saw a picture where the neck of the joint was actually narrower than the threads which worries me. It's to do with the shear forces when braking that will cause fatigue and snap it.
2. This one it much harder to say.....gulp...... You need to do something about the welding, a lot of the joints look to have very poor penetration and could pull apart like Velcro once road driving vibration has got to work on them. Also, the SVA/IVA man could pull you up on them, by which point stripping the car back to a bare chassis would be a nightmare.
Are you using a gasless mig? I've never used or seen what the welds look like immediately after welding hence the question. I have heard they are not a patch on a proper one.
I hope you take this as constructive criticism sa it is the only way it is meant.
Hat's off to you, and good luck.

Hi Dave
Fair comments on all!
I realised the issue with the front top ball joint and have now created a far more substantial wishbone. I guess the proof of the pudding was when i took it out on the road and the front wheel fell off!
That taught me two lessons, a) welding wasn't much good and wishbone was rubbish too!

Hence the previous comments about not liking the front geometry - there is an obvious difference between my creation and a lotus 7, i have no weight at the front, so maybe that will bet better?

As for the welding, well I turned the amps right up! This seems to be th trick with gasless, with gas MIG you can have the amps much lower but for some reason I have to have the feed high and the amps on full? maybe my old MIG is on its last legs?

I have tried to dismantle a few later welds with a hammer and they won't break, and cutting through shows a the weld is quite substantial. But I guess time will tell! When they are rubbed down and painted black they look much better

Today I was welding the frame for the rear engine cover, and I could not get a weld to hold at all! Seems to be luck, if the weld starts it flows nicely, if it sticks the weld splatters all over the place, really frustrating.

Ideally I would like to pay someone to go over them all (or all the important structural ones) Maybe oneday..

Regards
Nick

[nicktruman]

Dave Dax builder said:

Hi Nick.
Thanks for not taking my post the wrong way.

The loading on the top ball joint is not vertical, that is free floating as your suspension loads are absorbed through the lower wishbone. The loads are horizontal, and come into play when you brake, the wheel wants to stop and the chassis wants to go forward, this will try to bend the threaded shaft of the joint with the ball part trying to go backwards and the threads going forwards, you will have the whole weight of the car pushing the chassis forward.
I'm sure there is a formula for working out the potential loading, but as a guess you need to work out the distance from the centre of the hub to the top ball joint (Say about 6") and from the joint to the rear of the car (Say 10'/120") giving you a 24:1 ration. weigh the rear of the car (Say 1/2 a ton or 1100 lbs) divide this by 2 to allow for 2 top joints (Say 550 lbs) multipy this by the ratio of 24:1 gives a loading potential of upto 13,200 lbs / 5.8 tonnes of sideways/shear load on that thread...............I've probably got my calculations all wrong but you get where I'm coming from.....Where are the stress analysis boffing when you need one?

Hi Dave
My top ball joints are the huge ones not the skinny earlier type. I bought the wrong ones! I think the thread is over 20mm but I can't remember exactly.

[nicktruman]

I managed to get the engine running! But I had to install resistors on the 12 injectors and change them to high impedance

Edited by nicktruman on Wednesday 18th March 16:14

[nicktruman]

300bhp/ton said:

Very cool

I don't think it'll keep the reg though as it will need an SVA (enhanced one I suspect).

The regs say to keep the ID it must have an original (or new) non modified chassis plus 2 major components.

Well actually it says it must score 8 out of 14 points awarded:

chassis 5
steering 2
suspension 2
transmission 2
axles 2
engine 1

But it does say chassis can not be modified or 2nd hand.

BTW - what sort of hp/torque is that motor making??

Hi, thanks Mate! I know it will have to be sva'd or something but I can dream
As for power, should be around 450/550bhp the stock motor is 320 +15psi boost. tbh not really that bothered, it will produce more power than i need, it doesn't weigh that much either so power to weight should be awesome and anyway having the turbos strapped to a V12 looks cool.
Calculations predict that the car should do 0-60 in about 2.7 secs and have a top speed of 187 mph. However the same calculator also said it would wheelspin to 90 mph (no traction control or LSD)

I would be happy for now if it would just run properly. I started it this morning and backed it out the garage, ran beautifully for about an hour. tried later and started ran for a few mins the died. v strange, huge spark and petrol.

Seriously annoying as pushing it back into the garage on a gravel drive is hard work!

Regards

Nick

Edited by nicktruman on Wednesday 18th March 22:35

[nicktruman]

Hi, here's a video of the car i shot yesterday. I fitted fiat Punto tailgate struts to the rear engine cover and fitted the rear lights (only wired one side though). I also re-wired some of the electrics as they were draining the battery.
I also added resistors to the injectors to change them to high impedance, seems to work OK now with no PWM on the ECU, also might last longer at high revs.
All in all everything seems to work really well just now!
http://www.youtube.com/watch?v=-k_95tcZ0Oc
Still to do..
floorpan, sills, doors, windscreen surround, front suspension, make rest of nylon suspension bushes, fit nuts and bolts on all the suspension and shocks (only bolts at the mo nothing else , get headlights, find way to fit brake pedal rear light switch etc. etc. etc...

[nicktruman]

I have now made most of the passenger side sill and air inlet. It was really difficult to make and was probably the hardest bit so far! I had to make sure that all the panels fitted perfectly and had the right profile.
When the GRP has cured I want to fill the long sill sections with expanded polyurethane foam to give more support and rigidity. Tonight I closed the engine cover and it looks almost awesome (even if i say so myself .

[nicktruman]

hairykrishna said:

Awesome project. It's going to be a monster when it's finished!

Do you have any drawings of your chassis? I've always fancied an Ultima style car but they're a bit beyond my budget. This thread has started me thinking that I could maybe scratch build something similar...

Heh thanks Mate.
I have no pictures however the Ultima website has some good photos of the chassis exposed as does the parallel design website.
I made a wooden mock up 1st to test for stiffness, when the scale model was glued together it did not twist so was the one I chose. However, it did not stand being run over by the Ferrari


My problem was the engine is so heavy and I don't have an engine hoist, when i tried to use the RSJ over my garage the walls started creaking.
So I built the chassis round the engine and jacked the engine into the chassis.
Today I took the car out and turned it round so i can build the last side pod and sill. I also sorted out the wiring for the front fog lights which need bonding into the bonnet. The passenger side sill is now finished and i have made a frame to support it bolting the whole lot to the car. Just for fun I fitted a mock carbon fibre tread plate.


I also set the idle speed at the throttle bodies as the idle was way too slow. Now it ticks over at 1000rpm and picks up really nicely. I have one issue in that the alternator light does not turn off until the revs hit 3k any ideas?

Cheers
Nick

[nicktruman]

The latest..
I have fitted 2/3rds of the floor pan. I have the very front section under the suspension and the rear diffuser section still to do. I have also fitted the firewall between the cockpit and engine and most of the passenger side interior. Whilst I was making the inner sills I also fitted the two 300 watt speaker and hid all the wiring. It looks really smart now!
I have changed injectors to a lower throughput set 196 cc/min as opposed to 405 cc/min. This has put the fuel tables miles out, but it still runs, but the engine surges and hunts badly.

[nicktruman]

rhinochopig said:

Davi said:

rhinochopig said:

Please don't take this as harsh criticism - I think it's great what your doing, and is it's easy to comment from your sofa - but...the finish on that body looks terrible in those pics. Like it's made of paper mache = all lumpy with no sharp edges. Have I missed something?

Nick's doing it the (extremely) hard way - building lumpy then flatting and finishing later. Elbow grease? ahh yes 20 barrels over here please!

Ah, that explains it. I'd assumed he done the body in ply first and then produced a mould.

Blimey that'll take some effort - good luck fella!

Don't worry I know I have a mountain to climb! The front is bad, but in all fairness that was the first bit I made, the back came out OK but will need some work.
However i have tried to finish some of the back (to see if its doable) and it worked out nicely - but it will take a tonne of bondo
I guess after all the work to get it to here, its not too much of a big deal

[nicktruman]

Davi said:

andygtt said:

Im doing exactly the same to create my buck... but I have to say to get a finish even remotelly close to what I thinks ok I have had to put masses of filler in and its extremelly fragile due to the sheer weight of the pannels.
Of cause for the buck it doesnt matter but on a finished car I think it will crack terribly... Of cause the arms like popeye will be a bonus lol

I thought you roughed the shape in foam and plaster on yours first Andy? Obviously the workload is massive on any buck forming, I just tend to use considerably more fragile but easier workable materials on a buck - trying to sand and rework a thick multilayer GF shell is horrific, absolutely soul destroying in my experience - that's before you even get to the filler! As you say the amount of filler needed on road going panels is likely to crack badly

skwdenyer said:

Doing it this way does at least mean that Nick can, if he likes, then take moulds from the finished article to produce more conventional panels, whilst still being able to build up "on the car".

Reading his various threads on forums, he doesn't want moulds laying around so won't do this - I believe a serious mistake.

Heh Guys! Don't be too cruel! The car isn't that bad. Ideally I would have got a mould but there is a real shortage of Zonda owners willing to let me copy their pride and joy ;-)
In an ideal world I should have made a female mould and done what you suggested, but money is/was tight and to make this car I could not afford to duplicate all the GRP costs. I know thats a lame excuse but alas its true.
However
As i said on the rear section i have tried to experiment in making it look better, and it seems to work well.
I rubbed the bad bits down with a rotary sander and filled with P38. Then I glassed over with fine tissue. When this went off I rubbed down again then painted resin over that. It came out really well! So I figure I could do that for the whole car?
The front looks bad, too much resin and matting too quickly, but then you learn by your mistakes. However, If i fill the creases on the inside then layer a coating of 400 gram matting inside. When I rub/grind out the creases I should have a sound shell? Then I just layer again with tissue matting and paint top coat resin over. That's the theory, it certainly works on small sections..
I do know that when peopke come round and see it (your all welcome!) in the flesh (so to speak) the view is its quite awesome, i think the body looks worse in pictures because of the shadows but i might just be being sensitive

Regards

Nick

[nicktruman]

Davi said:

nicktruman said:

Heh Guys! Don't be too cruel! The car isn't that bad. Ideally I would have got a mould but there is a real shortage of Zonda owners willing to let me copy their pride and joy ;-)
In an ideal world I should have made a female mould and done what you suggested, but money is/was tight and to make this car I could not afford to duplicate all the GRP costs. I know thats a lame excuse but alas its true.
However
As i said on the rear section i have tried to experiment in making it look better, and it seems to work well.
I rubbed the bad bits down with a rotary sander and filled with P38. Then I glassed over with fine tissue. When this went off I rubbed down again then painted resin over that. It came out really well! So I figure I could do that for the whole car?
The front looks bad, too much resin and matting too quickly, but then you learn by your mistakes. However, If i fill the creases on the inside then layer a coating of 400 gram matting inside. When I rub/grind out the creases I should have a sound shell? Then I just layer again with tissue matting and paint top coat resin over. That's the theory, it certainly works on small sections..
I do know that when peopke come round and see it (your all welcome!) in the flesh (so to speak) the view is its quite awesome, i think the body looks worse in pictures because of the shadows but i might just be being sensitive

Regards

Nick

Not trying to be cruel Nick, just trying to help - it's a mammoth task you've undertaken and I don't wish to detract from your achievements or your enjoyment of the project one tiny bit, rather don't want to watch you make mistakes that are avoidable if you'll take a little well intentioned advice to stop seeing you disappointed when it's finished!

I think the biggest problem you are facing is a lack of experience with glass fibre and the long term effects of movement and stresses on it. Grinding down, building up with filler then coating over the top with a thin layerwill quite probably make a perfectly sound looking shell - but structurally it's going to be quite poor and it's likely you won't even make it to the SVA station before it cracks

Considering the cost of the resin and matting needed to make a mould, I reckon you'll spend a hell of a lot more getting your current work finished to a standard that will stand up to a coat of gloss paint than you would have making a buck and moulding from it.

Edited by Davi on Monday 20th April 14:31

Hi Davi, no arguments there! YOu are right I have no experience with resin, the damn stuff keeps moving and sagging even after it gone hard

Sometimes I wish I could just get an off the shelf body but that's not going to happen.. I think I need to finish off the last panel (the drivers side sill and air intake and take stock of where I am. On the + side..

If you guys want projector head lights for you carts i have found the ultimate source! Suzuki AY50 moped lights. Ther are twin Projectors and can be picked up for around £15 a pair.

So that leads to my next project, I need to fabriate and make 2 head light units. But I want them to be great. See picture below, any ideas??

[nicktruman]

Davi said:

If it's moving and sagging after considerable cure time you've gone wrong somewhere - may just be not enough layers / reinforcement area's but it could be something in the chemical mix or mechanical layup. Poorly bonded layers (heavy resin to fibre ratio usually a good example) or poorly stippled and rolled work can cause voids and a weak panel.

Lights... Be careful - IIRC bike / scooter lights do not throw the correct beam and will not get through SVA (may be incorrect but sure I read that somewhere recently!)

as to making the units... make a buck and take moulds Work with some hard insulation foam, easy to sand and carve to shape, then a thin tissue of resin, then final fill and smooth only with filler!

Edited by Davi on Monday 20th April 15:53

How long is it supposed to take to cure?
The lights are e-marked so OK/legal for UK road use.

[nicktruman]

andygtt said:

Nick Im in no way trying to diss your car, I think its awsome and as a fellow scratch builder Im 100% behind you as I know its easy to talk the talk but getting on and doing it is something else.

The problems you are having with it moving is exactly what Im experiencing... I had to remake my rear wheel arches by 2 inches recently because it had moved and the body was welded to the chasis and I have a subframe to hold it so how its moved so far is beyond me... but it definatelly had.

I dont want you to build the body only for it to move and crack so badly that you cant even take moulds from it later and end up having to throw it away... that would be criminal.

As a constructive solution, why dont you do what I have done to my buck and build a steel sub frame and bond it into the body? heavy yes but will really help movement.

Hi Andy
My body has a steel subframe (skeleton)! I integrated it into the polystyrene so when i laid the glass fibre it bonded to the steel. When i removed the buck I laid extra layers of glass over the steel on the inside for extra strength.
Where it has sagged is in the areas like air intakes etc.. But I'm sure I can reinforce those parts.What i meant by sagging happened within a few days of laying up. The glass on the bonnet was lovely and smooth. By the time it had cured it had developed wrinkles (gravity?)! I didn't have the same issue on the rear section which is very smooth, although as someone pointed out in another forum distorted on one wheel arch

Maybe if i leave the car looking like "paper mashe" Pagani will buy it off of me to save it being the only Zonda people ever see!

Ah well maybe I should have just done the car in secret and not told a soul - seemed like a good idea at the time. Anyone want to finish it off?

[nicktruman]

Tony 1234 said:

Nothing to add, just think this is a good thread.

Hi Tony welcome to the Nick bash

[nicktruman]

Sorry guys i was having a sensitive day, everything piling on top!

I appreciate that my body is awful, I know I should have made it in a different way, But we are where we are! and like Andy says it suited me to do it this way.

So I can't afford to make another body, I can't make a mould then another shell!

So what options do I have.

Andy, what is this board you mentioned? I have no shortage of power (550/600 bhp)so weight isn't really an problem! although at under a tonne it would be cool to stay as lite as possible.

I have some creases and sags, but i also have plenty of commitment and energy to make as good as possible. Surely if I sand the sags down so they go and lay up extra layers of matting on the inside the body will smooth out? I can't see why it couldn't?

I read on a lambo site that the doors are made in situ, by screwing board across the door opening and laying up the glass from inside the car. That way you get an exact fill for the door hole. But to do that i need to get some release agent to paint the MDF with, what do you recommend?

The lights.. They should have been here by now, coming via courier, my luck they will turn up just after my wife gets home and thats me in more trouble

I realise the pattern might not be correct, but there is a plate in the light which targets the pattern that may need adjusting to the correct car shape.

Regards

The Madman!

Edited by nicktruman on Tuesday 21st April 10:59

Edited by nicktruman on Tuesday 21st April 11:23

[nicktruman]

andygtt said:

foam sheets about 1/2 inch thick, bond these to the back of your body and fibreglass 2 layers over them and it will become extremely rigid.

http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Po...

Andy
This is good stuff!
So how about this for an idea.

I have some folds in the front section which although strong are damn ugly! The body is very strong, I probably laminated way too many times!

As I said before the wrinkles look worse due to the shadows of the camera's flash. Here is a high res picture of the worse wrinkle on the bonnet.

The wrinkles start on the inner surface, which as you know is really smooth. I figure I could fill that inner surface and lay up one sheet of matting on the inside to cover the filled area. Then bod a sheet of this foam sheet over that. Maybe pop riveting it in place so ensure great adhesion? (these would be drilled out afterwards and filled.
Then lay up under as Andy says with 2 extra layers of laminate.

This added to the existing steel frame would give me a very thick nose cone, but still light.

However, I am still left with a finish on the front that needs addressing?