alloy radiator

SeanDezart said:
Crossflow better Mr Gaskin.

Mechanical fan noisy too - no reason why a road car, even standard can't switch to leccy fan (s) and dump the mechanical one -
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Why is it better - just want to know that's all? You have criticised me in the past for using non-descriptive words ;). As water cools it flows down through the rad I'm guessing that the crossflow rad slows this process down so may cool it more?

Noise, I think the whoosh of the mechanical fan softens the underbonnet noise (tappets etc) of a Z. Or is that my imagination :unsure: Yes electric fans are good but is it worth the trouble and cost on a road car that does low mileage?
 
Quote from Stewart Racing:

Cross flow radiators are superior to upright radiators because the radiator cap is positioned on the low pressure (suction) side of the system. This prevents the pressure created by a high-flow water pump from forcing coolant past the radiator cap at high RPM. As mentioned in the radiator cap section, an upright radiator should be equipped with radiator cap with the highest pressure rating recommended by the manufacturer. The system will still force coolant past the cap at sustained high RPM.
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Factors to consider in a cooling system:

1. Surface area of cooling fins - more is better. Determined by dimensions of radiator and number of rows of fins.
2. Speed of flow - efficiency of water pump a factor.
3. Turbulence in fins - modern design increases turbulence and improves the cooling efficiency.
4. Pressure within the system - increased pressure (without blowing the cap or popping hoses) = raised boiling point of water. High pressure "performance" radiator caps readily available for more modern Nissans (Z31 onwards).
5. Lower temperature thermostat to bring the radiator into circuit earlier. Nismo stats available for VG and RB engines - e.g. on the RB and VG30DET the Nismo stat opens at 62 degrees whereas the standard stat is 76.5 degrees.
6. Use of a "water wetter" cooling agent to improve the heat exchange and raise the boiling point. Antifreeze does this to some extent, but products like RadHib from Millers (in stock at MJP - advertising break over) used in addition to antifreeze will enhance cooling and improve resistance to corrosion (particularly important for alloy rads and alloy heater cores - as Z32 owners will tell you).

Probably more to add - just off the top of my head for now...it should go without saying that every aspect of the cooling system should be as good as you can make it. If building an engine, check that you are not using a block that is furred up with rust and crud. Don't be tempted by Rad Weld and similar, just fix the problem!
 
Rob Gaskin said:
Why is it better - just want to know that's all? You have criticised me in the past for using non-descriptive words ;). As water cools it flows down through the rad I'm guessing that the crossflow rad slows this process down so may cool it more?

Noise, I think the whoosh of the mechanical fan softens the underbonnet noise (tappets etc) of a Z. Or is that my imagination :unsure: Yes electric fans are good but is it worth the trouble and cost on a road car that does low mileage?
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Good guess Rob but all you had to do was ask - there are many years of Z racing experiences available. Thanks Mr F for putting that btter into words.

Noise - noisy tappets Mr Gaskin? .... a more manly affliction to cover the fan noise would be induction roar...:thumbs: !
 
Just to add, antifreeze is bad for cooling performance; the more you add the more the viscosity of the water changes and the worse the cooling becomes.

Also, optimal radiator fin density depends on the fan you use. Densely packed fins will perform worse if the fan static pressure is insufficient, more widely gapped fins will perform better in most situations where you are not using a really high CFM fan.
 
Rob Gaskin said:
Mmmmmm I wonder how relevant that is to Z owners. My car is always pushing water out - it's a damn nuisance
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---Quote (Originally by SeanDezart)---
Good guess Rob but all you had to do was ask - ---End Quote--- I did plonker:

*Why is it better - just want to know that's all?*
***************


Nice bit of editing Rob !:thumbs: Well moderated............

You don't believe anyone or what ? - you've just been shown why it's better and you immediately question it !

If your car is pi*sing out water - it aint normal and it's more than a nuisance, at best yhou might damage your engine, at worst (on a track-day) it can have worse consequences for others.

Now chill out and stop having a go - I'm much better at it than you and it'll only end in tears.:D:cheers:
 
Sean, I'm not going to explain the lost water comment if it was 'lost' on you. My car does not use water, oil or much petrol :thumbs:

And please don't turn every Thread into a fight it gets very boring.
 
Rob Gaskin said:
And please don't turn every Thread into a fight it gets very boring.
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I don't ! Haven't for ages but this :

***************

---Quote (Originally by SeanDezart)---
Good guess Rob but all you had to do was ask - ---End Quote--- I did plonker:

*Why is it better - just want to know that's all?*
***************

from you IS boring Rob - don't start please.

My car is always pushing water out - it's a damn nuisance ;-) Yep - lost on me - I was being serious and tryiong to be constructive.

You're just one of these people who once they've decided - that's it. I turned over the leaf ages ago mate - you should've noticed by now.:thumbs:
 
So why is crossflow better? I'm not saying its not better. I'd just like to know technically why so if someone asks me why I've used a crossflow rad, I don't look like a plonker when I can't answer the question.

I like to ask questions so I can learn something. Being told "because its better" or "that's how it's always done" doesnot help or answer the question.
 
Essentially more cooling surface area in an equivalent footprint compared to a vertical flow radiator. Plus the pressure advantage already noted above - crossflow more likely to vent air than water.
However, you could argue that a multi-row vertical core could be just as efficient as the same number of rows and area arranged as a crossflow.
Where bonnet line is important, crossflow radiators can be made lower and wider more easily (?).

All things being equal in terms of construction, materials and cooling surface area - no difference between vertical and crossflow!
 
my local rad shop makes alloy rads for various rally and race teams (bloody expensive mind) and in his opinion a cross flow rad is no more efficient in cooling than a vertical rad. the same core fitted in either x/flow or vertical will produce the same cooling.he describes it as simple physics
 
Dug my old cooling diagram up that i used to pass around ,may be of use explaining two common styles to someone.Never had a problem installing either setup on any car.Plus pic off net for anyone unfamiliar with conventional cap operation.
 

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SeanDezart said:
Jorgen - stupid question but where is your throttle linkage please ?
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Hi !

I have change to a cable instead, its more easy to adjust and synchronise the Webers :)

You can see the cable with silicone protection on one of the pictures !

Regards
 
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