37 replies to this topic

[Steve.i.am]

Familiar issue - the engine temp on my SC ratchets up quite quickly on warm trackdays. Its always been like it - last weekend at Snetterton for instance, it was a warm day (25 deg c) and the car was getting to 106+ after just 10 mins or so hard driving. I got carried away scrapping with an M3 and got it to 110.

 

I want to try & do something about it. Like:

 

1. Remove one of the twin fans to improve airflow

2. Block up all the gaps around the rads and rad surround to force as much airflow through as possible.

 

I think some others did this sort of thing - Chill? Captain Vimes? If so did it have much effect?

 

Any other ideas that aren't too drastic (ie I don't really want to get into changing the CC rad for a smaller one etc)?

 

cheers.

 

PS the water pump was changed a couple of years ago so is new, and I use a 75:25 water:coolant mix.

 

[smiley]

Is your pcv setup to go back into the inlet pipe? (ie the laminova's could do with a cleanup?) 

[Steve.i.am]

I don't have a pcv setup - the cam cover breather exits to atmosphere out the diffuser. I don't *think* I have an issue with intake temps - I don't have a TMAP so who knows but the car doesn't lose any power as it gets hot or on hot days compared to cold ones.

[CHILL Gone DUTCH]

Just to confirm this is engine water temp not iat

[Arno]

2. Block up all the gaps around the rads and rad surround to force as much airflow through as possible.

This. Make sure ALL the air brought into the nose/crashbox is forced out the rad and can't leak away. Also make sure there's no pockets of air trapped in the radiator reducing it's active contact surface.
 
Also on VX'es the mesh in the nose of the car can be fairly restrictive to airflow.
 
Cutting it out, only leaving some edges and then putting in a Steinmetz copy plastic 'crate' grille (attached to the remains of the mesh) should open up the inlet air path a lot more, or fitting a more coarse mesh.
 
eg. Bentley style:



Bye, Arno.

[Steve.i.am]

Arno - thanks.

 

Chris - yes engine coolant temp, not IAT.

[Chris P Duck]

FLD style bonnet?

[Nev]

Simplest thing you can do is take your floor pan off and maybe your engine lid. Guaranteed improvement and reduction in rear biased weight.

[Captain Vimes]

I tried: - Blocking the radiator gaps - Running just 1 fan - Adding extra naca ducts in the under tray (had 4 in the end) It still got too hot plus with only one small fan and 2 radiators it couldnt pull the water temp back down in the pits. Zoobeef is racing his (stage 1) SC so needs durability in the heat. He has a smaller CC rad which allows more air flow through the water rad. Not sure what his water temp or IATs are like or if its been put to the test on a hot day yet...??? Options I was looking at: - Smaller CC rad and WC (not water closet) - Bumper cut-out for a small CC rad (or 2, one each side) - supplement the laminova oil cooler with an additional thermostatic operated air/oil cooler to reduce the strain on the cooling system - spal fan on the engine cover to pull air through the engine bay - sell the car and buy something that was built to drive around tracks I went for the last option... it worked! No problems with water or oil temps now!

[CHILL Gone DUTCH]

Water injection cools to at so source Cooler combustion

[CHILL Gone DUTCH]

I also removed the side grills

[Captain Vimes]

When I wrote WC I was thinking water cooling but meant water injection! Doh!

[Rosssco]

So I think the issue is primarily related to the engine cooling system, not really the charge air temperature, therefore I would have thought water injection (as we typically assume to cool in the intake charge) is of limited effect. Perhaps a spray bar type set up at the front would help! You'd get lots of very concerning-looking steam though

 

No doubt about it, the large full size pre-rad and twin fans (both in front of the main engine radiator) do produce a significant restriction to flow. As does that bracket over the front to support the fans.

 

I looked at top mounted fans, but as pointed out, the bonnet hinge support thing makes this impractical.

 

The current Exige 430 and the 3-11 uses twin chargecooler rads either side of the bumper, with vents on top of the wings, so that looks to be the optimal but extreme solution..

[Rosssco]

Zoobeef is racing his (stage 1) SC so needs durability in the heat. He has a smaller CC rad which allows more air flow through the water rad. Not sure what his water temp or IATs are like or if its been put to the test on a hot day yet...???

  Not sure how he is getting on either, but he's potentially got a bit of a virtuous circle going on there:

 

Smaller pulley - less intake charge heat - smaller pre-rad - better main rad airflow - quicker cooling recovery etc.

[CHILL Gone DUTCH]

When went from z22se to Saab my car ran significantly cooler ( bigger water channels a suspect ) 83 degrees when cruising ( z22se was 91 ish ) but think the stat may be cooler But the whole engine ran cooler even on track, but since installing the water injection the car runs no more than 90-95 on track and that's now with harrop and producing enough power

[CHILL Gone DUTCH]

Also worth mentioning a sweet spot in the ignition settings help to

[Captain Vimes]

Zoobeef is racing his (stage 1) SC so needs durability in the heat. He has a smaller CC rad which allows more air flow through the water rad. Not sure what his water temp or IATs are like or if its been put to the test on a hot day yet...???

  Not sure how he is getting on either, but he's potentially got a bit of a virtuous circle going on there:   Smaller pulley - less intake charge heat - smaller pre-rad - better main rad airflow - quicker cooling recovery etc.

Agreed. It may be the sweet spot without adding extra cut-outs or WI. And agree with the above summary of the problem too - the issue is that the massive CC rad blocks the main water rad. To solve the problem I think either the pro-alloy rad has to go and intake cooling needs dealing with some other way. Or the main rad needs supplementary support either through an additional rad, reducing the demand from oil cooling or reducing the heat build up some other way (WI, fans, vents etc).

[MartinS]

Mine was the same and was caused by that big second rad added when supercharged as it so effectively slows the air flow and puts one hot rad right next to another.

I made sure my water coolant mix was the best it could be, fitted a cool running thermostat (not worth the bother) cut vents in the rear of the bodywork, fitted turbo ears and they all made no difference.

I know that doesn't help but at least may save you trying some of them.

Extra naca ducts were my next idea (I have two here if you want them Steve) and would be an easy thing to do but doubt again it would change things much.

I always thought using a smalller rad (maybe even in another position)for the supercharger cooling would be the best idea especially as it slows the normal air flow and even after a session on track the water never gets that hot so is over engineered. Someone will most likely want your current one as I assume its probably a Pro alloy.

 

Martin S

 

[MartinS]

Extra thought, you could add a fan switch (very easy) and at least turn your fan on earlier.

 

Martin S

 

[Chacha]

I am about to supercharge my vx, my approach is to use “1/2 size” front-mounted cc rad and water injection. Hopefully this way engine cooling will not be too affected and WI will keep iat low.