[project] The Ultimate Track 205

[robcastle 0]

Just spent far to much time looking at this thread! Really interesting though, keep up the good work, hope to see it at a hill climb in the not so distant future, keep on with the updates.

Edited June 8, 2012 by robcastle

[rallyeash 155]

those AT power tb's are good in theory, i nearly went for them on my engine build but after speaking to engine builders who had used them and took them off and refitted jenveys due to not making the power i soon changed my mind...

[Cameron 16]

Yeah some people don't seem convinced by them, but I wonder whether some have really been giving them a fair chance. The guy at AT spoke very persuasively about how and why they're better than DCOE throttle bodies and as you say the theory does sound good. We certainly had a very positive experience on our Formula Student car compared to a Jenvey.

 

I think I'll give their direct to head ones a try, they're incredibly well engineered and that obviously appeals to me! I'll talk with AT closer to the time about how to build up an engine that will work well with them, and make sure that any head work compliments them too.

[rallyeash 155]

yeah would be interesting if the engine was spec'd to match, i just went safe and stuck with Jenvey.

 

Jealous of the dry sump kit, mines going dry sump over the winter...

[Cameron 16]

They were working on an XU kit last I heard.. might be worth giving them a call?

[rallyeash 155]

Sounds good, I'll give them a bell. What's ure plan for tank and lines?

[Cameron 16]

Not sure yet, that's a long way off at the moment! I'm getting a nice AC TIG unit soon so I may well make the tank.

[Sandy 191]

Jenveys are not the only bodies! I have to be honest, I'm not at all convinced by the ATP butterfly design and all DTH designs are extremely limiting in what you can do to develop the tract, in my experience the easiest aspect of the engine to optimise to find the magic. It's another case of internet hype and focus on numbers and theory over proven practice from what I've seen. The 106 bodies were a case in point, designed off the car with no development, wrong shape up to the head, didn't fit the OE tps position or fuel rail unions as intended; don't allow proper tract development due to the location in the engine bay and limited injector position and trumpet options. If they worked as nice as they look, they'd be great, but fashion over function so far I'm afraid, one for the Magpies.

Edited June 8, 2012 by Sandy

[Cameron 16]

Call me a magpie then.

 

Why would a DTH throttle body limit what you can do with the tract? Surely it's less limiting than a DCOE where you have a fairly long straight section in the throttle body itself? I've seen these on a Golf using nicely curved runners to get bonnet clearance, it's similar to having the curve in the manifold, only you're not obligated to have it in such a tight space.

 

Ok so what I know about engine tuning doesn't amount to much, it's not my forte so I could well be buying into the hype. But until someone shows me like-for-like Jenveys vs ATP's to prove that they don't work I'm afraid I'm gonna be very sceptical.

[stefan 4]

What about something like this?

 

http://www.jenvey.co.uk/home/twin-throttle-bodies/twin-bodies-dcoe-style-30mm-long/jenvey-dynamics/ts-body-40-50mm-pair-tspxxi

 

It would be sort off in between DTH's and standard Jenvey ITB's. One could still get reasonable distance from valve to throttle butterfly without the packaging constraint issues, and still a wide choice of trumpet lengths.

[Sandy 191]

Attached is an overlay of a 106 engine, (in 2 installs), the only difference being the red line is ATP DTH bodies (using the longest possible trumpet) and the black line Weber DCOE pattern bodies on our custom inlet (not my ideal trumpet design either). Both in the same rollers, same mapper.

 

 

There are even more dramatic examples, but that's the clearest.

 

With DTH bodies you are bound to the designer's thoughts, the butterfly size and location, the injector location in most cases, the angle to the head, the porting to the head (extremely difficult to match DTH bodies, compared to a manifold) and in the ATP case, the trumpet choices are extremely limited. If you want to use the inlet design parameters to optimise the engine, you're ham strung with DTH bodies; you'll most likely miss the magic.

 

The best off the shelf kit we've tested for the Duratec (overall performance rather than just top line), is the SBD/Jenvey kit, which has the bodies at the outer end of the tract. In all the development I've done, I've found absolutely no evidence that the butterflies need to be close to the head.

Edited June 9, 2012 by Sandy

[Cameron 16]

Thanks for taking the time to post that up, it's much better to see evidence than just reading words so I do appreciate it.

 

Yeah, they're valid points actually and something I probably overlooked.. if they're CNC'd to a standard port shape then there's very little chance they'll match perfectly to the actual ports, what with core shift etc, but even more so when the had has been hand-ported; with the throttle so close you have a very short length to blend into the head if need be.

 

Have you tried any of their DCOE type throttle bodies?

[Sandy 191]

I had seriously contemplated using their DCOE bodies on my engines, we did a JRE Pinto with them last year, they worked fine, but nothing exceptional compared to what that spec normally does on others and John really wasn't confident about the safety of the fuel rails (for hard use) and found the linkages very fiddly. Neither of us are entirely happy with any of the throttle bodies options available to us currently and we're very open minded to a better way; but on what we've seen so far, it's not ATP I'm afraid.

Products these days are sold easily on appearance and "potential" performance. "Buy it now" culture!

[Cameron 16]

Thanks, I'll certainly take a few questions to AT before I consider which route to go down. I do like the SBD Jenvey kit, and they certainly seem to know their Duratecs.

 

On a different note altogether, I've had the last week off work (with all the bank holidays it seemed rude not to) and been thrashing out my space frame design so that once our workshop is up and running I can get cracking with the build. The most difficult part has been finding rocker positions and ratios that work and give me a consistent 1:1 installation ratio - not as easy as it sounds!

 

For anyone who's curious, the installation ratio is just fancy words for the relationship between wheel travel and damper travel, it may sound fairly trivial but it's absolutely critical. A ratio of 1:1 means that your spring rates and wheel travels are all easy to work out, and makes tuning easy later; it also means your dampers get an easier time.. think about how the rear dampers on a 205 sit, their IR is about 0:3 which means everything has to work 3 times as hard. The ratio also needs to be consistent throughout the wheel travel to keep things predictable, which isn't as easy as it sounds either. It's a pretty tedious process of finding a location that will package well; then experimenting with rocker geometry until you have something that works, or more often than not, binning it and starting again!

 

So my eyes have been back and forth between suspension software, CAD software and my Excel super-duper-calculator.

I had originally wanted to go for pull-rod suspension for the low CoG benefit, but I couldn't come up with something that cleared the oil pump without making it really complicated so have opted for push-rods instead. This also puts my dampers in places that will make adjustment nice and easy, so it's a win-win.

 

That left me with a completed space-frame weighing 129kg or thereabouts, which brought me to the next laborious process of trying to trim the weight out without sacrificing stiffness or strength. So armed with another fancy computer program (ANSYS this time) I did a whole series of simulations until I had something I was happy with. Many of the tubes are mandated by MSA regs which seriously limits things, but with enough tweaking I got it down by 4kg to 125kg - that's as low as I'd like to go without sacrificing strength. The torsional stiffness more than doubled from 7kN/Deg to 15.5kN/Deg, a lot of which was down to tweaks on the front end. (Chassis stiffness is also mega important!)

 

So without further ado..

 

 

 

 

 

There's a fair bit more work I need to do before I can get started - both in the unit and on the computer - but this brings me a lot closer! Once those bits are all done I'll get the AC TIG welder I've been dreaming of for the past couple of years and put in a tube order.

 

Edit: Someone asked before, what do all the colours mean? For anyone who missed my response, they relate to the tube dimensions. The mid-blue and green are MSA mandatory spec and can't be changed, the rest are to my own spec.

Edited June 10, 2012 by Cameron

[EdCherry 34 1 Cars]

I'd disagree with your suggestion that a 1:3 ratio means everything works 3 times as hard (and that sticking with 1:1 is easier), but otherwise it all seems pretty good so far. Glad you finally got a finalised design, what trans units have you decided on finally?

[Cameron 16]

It's simple mechanics Ed, so I'd love to know why!

 

I'm going for a Sadev Type 9 sequential and a Ford 7" rear diff, currently trying to decide whether to use Sierra outboard drive flanges / hubs / wheel bearings or to come up with something of my own. The parts are expensive due to the kit-car demand so it may well be worth having my own made up, and also means I can save weight!

[dale205mills 39 7 Cars]

 

 

I'm going for a Sadev Type 9 sequential and a Ford 7" rear diff, currently trying to decide whether to use Sierra outboard drive flanges / hubs / wheel bearings or to come up with something of my own. The parts are expensive due to the kit-car demand so it may well be worth having my own made up, and also means I can save weight!

 

If you decide to run for sierra set up then give Gary at RS cosworth breakers http://www.rscosworthbreakers.co.uk/ he has complete rear set ups off sierra's down there and I am sure he would sort you out with something and he all so has a lot of other stuff that mite be up you street from race cars.

[Cameron 16]

Thanks Dale, good link there!

[dale205mills 39 7 Cars]

The site is down at the moment but it should be online soon and you can take a look inside and look whats there but its best to ring him or even pop down and you will see stuff that most people never see or things that we all saw when we used to watch touring car racing with the rs500's spiting flames out of the exhaust back in the day.

[Cameron 16]

It seemed to work for me! I love places like that but hate them at the same time.. Touring Car Spares is another awesome but dangerous website.

[Sam 4]

It seemed to work for me! I love places like that but hate them at the same time.. Touring Car Spares is another awesome but dangerous website.

 

Tell me about it. I spent a fortune with Tony, only to sell it all again heh.

[Cameron 16]

Yeah I was dangerously close to spending a lot of cash on that XTrac rear diff.. lovely piece of kit but total motorsport porn overkill!

[EdCherry 34 1 Cars]

Hey ho im not going to argue if you see it a different way, its your design anyway.

 

TCS is closing down by the looks so you might want to make Tony an offer on the Xtrac gear...

[Cameron 16]

Well, without coming across all cold and engineer-like; there's only one way that mechanical principles can be interpreted, there's no such thing as an opinion.

[Cameron 16]

PREZZIES!!

 

 

 

I picked up a set of spanking new Caterham CSR wheels today, after a bit of a dilemma over what wheels to get I eventually stumbled upon these and found they're perfect for my needs! They're 15x6.5 front, 15x9 rear and a very nice design; not quite as light as Ultraleggeras but I'm going to have to compromise a little weight to get the sizes I need, as I didn't want to fork out for split rims.

 

The width difference is a little noticeable.

 

 

Now I need to get them modelled in CAD and package check my brakes etc.

Edited June 12, 2012 by Cameron