Functional Louvers/ Underhood Heat Excavation

[2mAn]

I have a 68 Datsun Roadster with the 2L motor, and Mikuni Sidedrafts. I want to add louvers to the hood as I plan on vintage racing it, and was told by Peter Brock that the Roadsters have a problem with heat cooking the carbs under the hood. 

Heres a pic of where the carbs sit in the motor. Nothing new to you guys

 

 

Heres a straight on shot, thinking of that lower ridge area on the driverside as one possible location. The other is the center, behind the radiator exit to draw it out, but I dont think that will work with its location and the hood scoop. Maybe that has to stay as-is 

 

This last pic is the bottom of the hood, just to give you an idea of what it looks like and potential locations of punching the louvers

Basically, I have a few options Im considering and looking for input.

1: Behind the radiator exit, angled up/ out of engine bay

2: In front of the carb, angled down/ into the engine bay

3: Behind the carbs, angled up/ out of the engine bay

4: At the back strip of the hood to draw all the heat out

 

 

 

[datzenmike]

A sheet metal heat shield between the exhaust and the intake/carbs would help block radiated heat.

 

Insulating the fuel line and even better, a fuel return line that circulates hot fuel away from the carb inlets and replaces it will cooler fuel from the tank.

[docbainey]

Campaigned a DP 2000 in the late 70s early 80s. Never had that problem. Maybe if your sitting in traffic, but then you aren't racing. Like Mike said, need a really good heat shield between the carbs & exhaust, bond some insulation to it, bring it over to the inner fender panel. Re-route your gas lines, right now you have them sitting over the header. Find away to bring fresh air in. If your insistence on fkng the hood up, just put the louvers over the carbs facing forward. At that point who cares about aesthetics. You'd probably be better off putting in a naca duct. Depending on what vintage racing association you plan on competing in, louvers could be a no no, not period correct after all.

Edited July 11, 2019 by docbainey

[Crashtd420]

Couldnt that big scoop on the hood be used?

Cut a hole and add some sheet metal as a duct or something.....

[datzenmike]

Heat soak happens mostly when stopped or just after shut down or low speeds.  Unless you have a fetish for those slotted louvers DON'T cut the hood up. Vintage race it first as there may be no problem at all. I detest louvers.

 

Adjust the hood latch so it doesn't close all the way at the back and it there's a rubber seal peel it off. This will let the hot air out.

[docbainey]

After looking at your roadster thread and realizing your never going to cut the windshield off to make a proper race car, I take it you're not going track racing but going to run those rich people things on public roads , the Mille  things? Last run in 1957? In Italy? Wayne Carini comes to mind. Nothing wrong with that. Heat shielding under the carbs and maybe header wrap, get rid of the rubber fuel lines unless you want to see your car burn to the ground,  better yet relocate the fuel lines to the back of the engine compartment not routed on the engine, there's probably a fuel return line that's been butchered  out of site unless your car is pre smog, put in an electric rad fan, get your radiator boiled out and bypass your heater core, you're in  California after all, what do you need a heater for?  just one less thing to fail. Make sur the coolant overflow system is up to snuff. The hood does have a functional scoop, but the limited airflow goes to the top of the rad. Get a custom cross flow rad and then you can take advantage of the hood. But if you don't deal with the oiling issues and the other engine 'opportunities', it will all be for not, but California road crap, its probably all good. Doubt you'll be turning over 6K. U20s eat rod bearings with out proper mods when revd, and the over square short rod U20 with big valves begs to be revd. One good thing, doubt you'll ever break the crank!

 

Don't louvre the hood. You already fd it up drilling holes in it.

 

Just my 2cents.

[MikeRL411]

Leave the heater core installed and run with the heater "on", it's a free extra radiator capacity.

[datzenmike]

I've done this in a pinch and it WORKS!!!

 

If heater core leaks, never join the hoses together in a closed loop. If you do make sure the pipe is plugged.

[2mAn]

On 7/11/2019 at 5:52 PM, docbainey said:

After looking at your roadster thread and realizing your never going to cut the windshield off to make a proper race car, I take it you're not going track racing but going to run those rich people things on public roads , the Mille  things? Last run in 1957? In Italy? Wayne Carini comes to mind. Nothing wrong with that. Heat shielding under the carbs and maybe header wrap, get rid of the rubber fuel lines unless you want to see your car burn to the ground,  better yet relocate the fuel lines to the back of the engine compartment not routed on the engine, there's probably a fuel return line that's been butchered  out of site unless your car is pre smog, put in an electric rad fan, get your radiator boiled out and bypass your heater core, you're in  California after all, what do you need a heater for?  just one less thing to fail. Make sur the coolant overflow system is up to snuff. The hood does have a functional scoop, but the limited airflow goes to the top of the rad. Get a custom cross flow rad and then you can take advantage of the hood. But if you don't deal with the oiling issues and the other engine 'opportunities', it will all be for not, but California road crap, its probably all good. Doubt you'll be turning over 6K. U20s eat rod bearings with out proper mods when revd, and the over square short rod U20 with big valves begs to be revd. One good thing, doubt you'll ever break the crank!

 

Don't louvre the hood. You already fd it up drilling holes in it.

 

Just my 2cents.

Lots of assumptions here... Im not a rich person, Im just a guy like many others who likes modifying cars within a reasonable budget. That reasonable budget is what is stopping me from hacking off my windshield to make this Roadster a track ONLY car. I can and will be taking it to the track. If eventually I have the luxury of making it a track only car, there will be more cutting...

 

I plan to drive this car to the track, at the track, back home from the track, to work sometimes, on the many canyons we have out here and anywhere else I can. Hacking the windshield limits this...

 

BTW The hood already had holes drilled from the factory, maybe you forgot since its been so long?...

Before, totally stock:

 

After:

 

Anyways, back to what the thread was about: louvers and expelling heat from the engine bay. I already have a heatshield between the carbs and headers, and already wrapped the headers, so I guess I will make some other changes associated with keeping the fuel lines cool and extending the heatshield (both things I had planned). 

 

I guess thats all she wrote for this thread without derailing it much. 

 

Feel free to go shit on the build thread and we can discuss my other choices there.

 

-Simon

[datzenmike]

You're assumption is that there is going to be a heat problem. Rather than cutting a good hood up, first see if there really is a need to, then try the suggestions to limit/mitigate any heat problems. I think every post was about dealing with heat so not really derailed. I'll add that a 'cold air package' could also be added. As to adding more holes to nowhere in the hood I don't see how this removes anything but a little weight at the expense of structural integrity.

[2mAn]

22 hours ago, datzenmike said:

You're assumption is that there is going to be a heat problem. Rather than cutting a good hood up, first see if there really is a need to, then try the suggestions to limit/mitigate any heat problems. I think every post was about dealing with heat so not really derailed. I'll add that a 'cold air package' could also be added. As to adding more holes to nowhere in the hood I don't see how this removes anything but a little weight at the expense of structural integrity.

 

In the OP I said that this is what Peter Brock told me. He said underhood heat was a problem...

 

I agree that you haven't been derailing, and have been adding ideas... I actually will explore the idea of relocating the fuel lines, there isn't much space to re-route the lines. I wanted to switch to making my own hard lines, but I'm pretty sure those will heatsoak faster than a rubber/ cloth line would.

 

I also want to make a heat shield for the brake master cylinder, we'll see what I can come up with on that.

 

The whole idea that started all of this was to find a way to get the exhaust a way out, rather than shielding the heat...  

[datzenmike]

Peter Brock works in absolutes. Full bore, all out, super modified high HP balls to the wall racing may show some heat related problems. I would wait and see first.