C3 Race Car Build

[Oneball]

Cant remember now, will have to have a look at the board in the morning, around 2.5-3 I think

3 caster -0.75 camber. Might add more comber at the expense of caster but need the suspension to settle. Remember that it’s a race car and they don’t make good road cars usually

 

[Oneball]

Fire extinguisher all plumbed in and breathers too

 

[johng]

You've got a nice open space between the engine and rad without the shroud in there. Makes access to your A arm nuts and bolts much easier than mine. Looks like you haven't got the rear arm shims much thicker than the front ones, or is that just my eyesight?

 

[Nick B]

The engine bay looks pucka Tim.

 

[Oneball]

You've got a nice open space between the engine and rad without the shroud in there. Makes access to your A arm nuts and bolts much easier than mine. Looks like you haven't got the rear arm shims much thicker than the front ones, or is that just my eyesight?

Yeah, not sure if the shroud is good or bad. As I’ve not got an engine driven fan I’m thinking it’s not really useful.

There’s twice as many shims back as front. It’s just half of them aren’t as shiny. My top arm pivots are the offset type too, so more camber to start with.

 

[Oneball]

Window seals fitted, what an utter pain in the butt and still not convinced the drivers door is going to close ok.

Cant get the front outside corner of the passenger t-top to sit down but given up for the day now, I can see fitting windows being particularly arsey

 

[teamzr1]

Yeah, not sure if the shroud is good or bad. As I’ve not got an engine driven fan I’m thinking it’s not really useful.

There’s twice as many shims back as front. It’s just half of them aren’t as shiny. My top arm pivots are the offset type too, so more camber to start with.

For the fan to achieve best cooling, a shroud is needed, as it generates positive pressure.

 

[Oneball]

For the fan to achieve best cooling, a shroud is needed, as it generates positive pressure.

The electric fan has a shroud so that’s sorted. The question is what effect the metal plate that normal fills the gap between chassis and radiator had if any? I think it’s just there for the engine driven fan.

 

[Roscobbc]

An electric fan (and one that is typically mounted to the rear of the radiator) will only cool an area of the radiator equal to the circumference of the fan blades. Fine for auxillary cooling perhaps if in traffic......just not efficient for general use except perhaps in a lower powered car. For a electric or engine driven fan to work efficiently it 'must' be mounted in a plenum (shroud) and spaced several inches from the radiator. All cooling air coming in through the front end of the vehicle should ONLY pass through the radiator core. The fan should only draw air though the shroud and radiator. To work best the radiator needs effectively to be sealed in to the front bulkhead so that ALL cooling air ONLY passes through the radiator. Obviously this will assist the normal flow or cooling air through the front end. The fan is simply there to assist at lower speeds.
The stock shroud needs a little help to be more efficient. Use corregated plastic sheeting secured with Sikaflex (or equivalent) to help achieve total sealing of the shroud to radiator. Make sure OEM rubber and foam seals between hood and front radiator mounting are in place. If an OEM water pump is used make sure that its impeller (if metal) hasn't corroded - replace if need be. Do use Red Line Water Wetter - is really is good for a reduction of a few degrees of water temperature and just 'tip the balance' cooling wise.

 

[teamzr1]

Also
Street cars need fan shrouds to allow the fan to provide airflow over the entire radiator and A/C condenser core areas when the vehicle is at little to no speed.

Those thicknesses result in a restrictive airflow, add crap building up them, then even more restrictive flow
Street use really needs a full shroud to overcome that


However, at a certain point in vehicle speed, 30-50mph, the airflow entering the grill from vehicle speed will become more than the cooling fan and shroud assemblies airflow and at this point the fan and shroud assembly becomes restrictive to airflow and more so at higher speeds.

Removing the entire fan and shroud assembly allows the air exiting the radiator to be unrestricted at high vehicle speeds, providing good cooling, but at little to no vehicle speed there is no airflow for cooling.

Keeping a fan but removing the shrouding removes most of the restriction at high vehicle speeds for improved cooling on track, while the fan allows for reasonable cooling at little to no vehicle speed

Good example of no shroud V having one below


Ever since GM had engine controllers and electric fans, in the tuning calibration they control at what temps, MPH and if A/C is on or off and when the fan(s) will be commanded on or off

Also considered is what coolant temp wanted and to change the Tsat opening (I tend to shim them to change their opening rate)

Then other ways to keep temps down
Water has a heat layer on top, it easily sheds that heat but has a lower temp to when it boils

Anti-freeze has a harder time in shedding that heat but boils at a high temp
For race purposes clearly not in freezing weather, so I bias the mix to more water than anti-freeze
But if in a lot of stop in go then more anti-freeze mixture then water.

 

[Oneball]

Thanks both fully up to speed on those bits but doesn’t quite answer the question of the benefits of this bit on a race car


Second question is what’s the random photo I’ve stolen off the internet of??

 

[CaptainK]

Thanks both fully up to speed on those bits but doesn’t quite answer the question of the benefits of this bit on a race car

Second question is what’s the random photo I’ve stolen off the internet of??

My guess would be a vehicle fitted with side pipes?

 

[Roscobbc]

Front end looks something like one of those Mako 'pointed' nose conversion kits from the late 60's/early 70's


















As for the 'filler' panel under the radiator - perhaps see what effect is has (both on and off) when on the track?

 

[teamzr1]

Thanks both fully up to speed on those bits but doesn’t quite answer the question of the benefits of this bit on a race car

View attachment 13759
Second question is what’s the random photo I’ve stolen off the internet of??

Under trays are used to reduce lift and drag
Higher speed going this causes car to be sucked down for better traction

Image you show helps air from being pushed upward to prevent front end lift

Notice on the C8 how closed off and smooth underside is



On my C4 ZR-1 the car would start getting light/lift at speeds above 160 MPH during high-speed Open Road Races
So I had made out of fiberglass a front end undertray and that allowed doing speeds over 200 MPH with little lift

 

[Roscobbc]

Early C3 starts to get front end lift above 120 mph (well, mine does does anyway)

 

[teamzr1]

My 1999 C5 would begin lift around 140 MPH
I decided to go a different route and had this hood build

It takes the pressure from the windshield and colder air is sucked into the engine bay
The front ducts are angled in such that as car in motion sucks the hotter air out of the engine bay to keep everything cooler
and prevent air pressure from building up causing lift



The to balance reducing lift at rear using a full wing I can adjust angle and a wicker edge on rear side which I can use different heights of wicker to adjust drag and the amount of downforce.

 

[Oneball]

That didn’t go well

 

[johng]

How did you do that?

 

[Oneball]

How did you do that?

Caught the edge with a screwdriver while trying to sort the t-top alignment

 

[johng]

I take it you are just a little disappointed!