Exposing your engine!
- Thread starter simonjrwinter
- Start date
Simon,
From my understanding it is advisable to maximalize the air intake into carbs coming from fresh air from upper inlets of your rear body and try to close as much as possible the hot air underneat from engine room.That's why some GT40 also had the plateau under the carbs.
I hope my enlgish was good enough to explain and that my assumption is correct.
So I woulod not suggest to open futher as explained by you.
Rgds
Fred
From my understanding it is advisable to maximalize the air intake into carbs coming from fresh air from upper inlets of your rear body and try to close as much as possible the hot air underneat from engine room.That's why some GT40 also had the plateau under the carbs.
I hope my enlgish was good enough to explain and that my assumption is correct.
So I woulod not suggest to open futher as explained by you.
Rgds
Fred
Simon, I think Fred is right, but I suppose you could still do it if you used lexan (temperature permitting) to maintain seperation of the two areas. You exhibitionist you /ubbthreads/images/graemlins/grin.gif
regards
Dave
regards
Dave
I would think that it is a big issue. All that extremely hot air can only rise into the carb zone, especially at low speeds, which is exactly what you don't want to happen. I honestly think that you would get a noticable power reduction.
As Dave says, if showing the engine is important to you, replacing the applicable existing rear clip section with some sort of heat resistant clear lexan may work?
If you really want to 'show off' /ubbthreads/images/graemlins/wink.gif invest in webbers or the webber injection that incorporates stacks.
As Dave says, if showing the engine is important to you, replacing the applicable existing rear clip section with some sort of heat resistant clear lexan may work?
If you really want to 'show off' /ubbthreads/images/graemlins/wink.gif invest in webbers or the webber injection that incorporates stacks.
The separation of the induction intake from the engine compartment is for two reasons. Cold air for combustion and aerodynamics. If the intake isn't separated it contributes to aerodynamic pressurization of the engine compartment which already has problems in that respect.
The concensus is right, the cooler the intake air temp. and also higher pressure it is, the more power you get. I am thinking of trying to loosely seal the engine from the carb intake as the 'shelf' section helps you to do.
If you want to cheaply lower your engine I was able to modify the standard engine mounts. By enlongating the fixing holes to the block which allows mounts to move in towrds the block, then the main mounting bolts slide down the angled slots in the chassis brackets. I think I got the best of an inch lower this way.
If you want to cheaply lower your engine I was able to modify the standard engine mounts. By enlongating the fixing holes to the block which allows mounts to move in towrds the block, then the main mounting bolts slide down the angled slots in the chassis brackets. I think I got the best of an inch lower this way.
Howard Jones
Supporter
There is more to it than the hot air going into the carb(s) inlet. The area under the rear clip gets very hot, but you knew that. The exaust headers have a suface temp of at least 600-800 degrees depending on coating, wraping etc. I am guessing, but I bet the engine bay gets to well over 200 degrees at idle speeds in traffic. That much heat will surely heat up the fuel in the carb bowls and will result in vapor lock sooner of later. Keeping the heat out of the upper engine bay is important, I've even considered cutting a few holes in the lexan at the high point along the top of the spider section to vent some of the heat at low speeds. These cars were never designed to cruze around at 10-20 mph. Search under lexan. I put up a link a few months ago that has just about everything you ever wanted to know about lexan and lexan type materials.
Simon,
Another tip that may help you,I had same problem on changing rockers and header cover whilst not having to lower engine on standard GTD engine placement.
Ctc Chris Melia if he has still some Guerney Westlake copy covers for sale.They are higher than the standard onces (ie:rockers will fit)but still fit without having to lower engine or adapt rear body cover inside.
I can send you a picture of my engine bay if want to by seperate mail.
Rgds
Fred
Another tip that may help you,I had same problem on changing rockers and header cover whilst not having to lower engine on standard GTD engine placement.
Ctc Chris Melia if he has still some Guerney Westlake copy covers for sale.They are higher than the standard onces (ie:rockers will fit)but still fit without having to lower engine or adapt rear body cover inside.
I can send you a picture of my engine bay if want to by seperate mail.
Rgds
Fred
Fali, did you do any type of testing to see if the window cut outs reduce the temp in that part of the body?
I'm asking becuase I'm considering doing this mod to my window before installing it,,,,,,but would like to know if it indeed makes a noticeable difference.
I drove my GT40NA around the block tonight a couple of times just to check for leaks, and check shift linkage since I had made some adjustments.
I noticed that the rear body got very very hot after running for only about 5-10 minutes, so I opened it up and let it cool off.
When I had my cobra, i used to open the hood immediatley after drving it so the heat wouldn't do weird things to my hood.
Looks like I may do the same with the Gt40.
Those stainless headers look nice,,,but they sure let the heat come out and cook everything in sight.
On my NZ kit, I am thinking of ceramic coating the headers and then wrapping them with the wrap stuff.
I've heard all the horror stories about the wrap turning headers into toast,,,,,,but wonder if coating them first will help them live longer.
All I know is all that heat under the bodywork makes me nervous.....
and this is something I want to keep as contollable as possible.
I'm asking becuase I'm considering doing this mod to my window before installing it,,,,,,but would like to know if it indeed makes a noticeable difference.
I drove my GT40NA around the block tonight a couple of times just to check for leaks, and check shift linkage since I had made some adjustments.
I noticed that the rear body got very very hot after running for only about 5-10 minutes, so I opened it up and let it cool off.
When I had my cobra, i used to open the hood immediatley after drving it so the heat wouldn't do weird things to my hood.
Looks like I may do the same with the Gt40.
Those stainless headers look nice,,,but they sure let the heat come out and cook everything in sight.
On my NZ kit, I am thinking of ceramic coating the headers and then wrapping them with the wrap stuff.
I've heard all the horror stories about the wrap turning headers into toast,,,,,,but wonder if coating them first will help them live longer.
All I know is all that heat under the bodywork makes me nervous.....
and this is something I want to keep as contollable as possible.
hmmm, has anyone tried installing a pair of fans at the very rear of the body (where the lovered panels are) to extract hot air?
A pair of rad cooling fans blowing out the rear clip maybe one way to go?
A pair of rad cooling fans blowing out the rear clip maybe one way to go?
Alain, the picture above is not my car. The guy's name is Dave. He has posted here once or twice. I took the photo at one of the car shows in California.
You should consider insulating the inside of the rear bonet (there are lots of posts here on this subject) specially the areas right above the headers. IMHO with no ceramic coating, header wrap or inner insulation, your paint will be damaged in the long run.
You should consider insulating the inside of the rear bonet (there are lots of posts here on this subject) specially the areas right above the headers. IMHO with no ceramic coating, header wrap or inner insulation, your paint will be damaged in the long run.
Thanks Faili,
my NA car does have a thin layer of goldish tinted foil type insulation on it,,,,,but it obviously isn't enough to do the job.
I also believe that raw(uncoated) stainless was a poor choice for headers as far as heat goes........although they look gorgeous.
I'm going to be in Indianapolis this week end to see some qualifying for the 500 and visit the NA factory.
While I'm there, I'll discuss adding more insulation to the rear body work.
my NA car does have a thin layer of goldish tinted foil type insulation on it,,,,,but it obviously isn't enough to do the job.
I also believe that raw(uncoated) stainless was a poor choice for headers as far as heat goes........although they look gorgeous.
I'm going to be in Indianapolis this week end to see some qualifying for the 500 and visit the NA factory.
While I'm there, I'll discuss adding more insulation to the rear body work.
I am not disputing what has been written about temperature concerns and certainly not disputing the benefits of cool air intakes, but something is just not ringing true here.
The Windsor engine is normaly used in an enclosed area under a sealed bonnet and with hot air blowing directly onto it from a front mounted radiator. And with hot air having almost nowhere to go except to rise to the fuel intake device at the top, surely the GT40 dynamics, even with the separation panels removed, are an improvement on this "normal" situation... or have I missed something?
/ubbthreads/images/graemlins/confused.gif
The Windsor engine is normaly used in an enclosed area under a sealed bonnet and with hot air blowing directly onto it from a front mounted radiator. And with hot air having almost nowhere to go except to rise to the fuel intake device at the top, surely the GT40 dynamics, even with the separation panels removed, are an improvement on this "normal" situation... or have I missed something?
/ubbthreads/images/graemlins/confused.gif
Hi Chris.
I had mine running with a laptop attached a while ago. It seems the intake air temp gets quite high once the engine is hot. This also happens in a normal car at slow speeds but the temp drops a lot when the car is moving. I need to experiment more, but indications are that quite a lot of the incoming air is coming up from below the separator. It possible we all should be talking about how to seal this area not open it up
Regards
John
I had mine running with a laptop attached a while ago. It seems the intake air temp gets quite high once the engine is hot. This also happens in a normal car at slow speeds but the temp drops a lot when the car is moving. I need to experiment more, but indications are that quite a lot of the incoming air is coming up from below the separator. It possible we all should be talking about how to seal this area not open it up
Regards
John
David Morton
Lifetime Supporter
Simon,
I think the rear area you are talking about behaves much like a plenum chamber. IMHO you will regret opening it up any further.
Dave
I think the rear area you are talking about behaves much like a plenum chamber. IMHO you will regret opening it up any further.
Dave
""Those stainless headers look nice,,,but they sure let the heat come out and cook everything in sight.""
""I also believe that raw(uncoated) stainless was a poor choice for headers as far as heat goes........although they look gorgeous.""
MATERIALS HEAT TRANSFER COMPARISON
Coefficient of Thermal Conductivity
BTU/ft-hr-F (70 F)
1010 Mild Steel -- 26.98
304 Stainless-- 9.40
(higher number means more heat transfer)
Numbers from a Burns TECH ARTICLE chart
So mild steel transfers 3 times as much heat as stainless.
IMHO stainless is by far the best choice of material in this application. Stainless also has the best maintenance characteristics. Header coatings typically need recoat at periodic intervals. Stainless would probably have more problems with coating than mild steel because it has a higher thermal expansion factor.
Stainless will last indefinitely with only an occasional easy steel wool cleanup just for appearance. Unlike chrome which blues stainless can be polished back to original very easily. Mild steel that is coated rusts from the inside and eventually needs replacement.
Insulate the underside of the rear clip, it's been discussed at length. Another option for engine bay cooling is to put additional oval ducts in the license plate area like on the original Gulf cars. You can also put a SS shroud over the mufflers. Robert at RF has also worked out a temp controlled fan cooling system which has been previously discussed.
It would be interesting to see a temp comparison between coated mild steel, coated stainless, and bare stainless. With the advent of inexpensive electrical thermometers this should be easy.
""I also believe that raw(uncoated) stainless was a poor choice for headers as far as heat goes........although they look gorgeous.""
MATERIALS HEAT TRANSFER COMPARISON
Coefficient of Thermal Conductivity
BTU/ft-hr-F (70 F)
1010 Mild Steel -- 26.98
304 Stainless-- 9.40
(higher number means more heat transfer)
Numbers from a Burns TECH ARTICLE chart
So mild steel transfers 3 times as much heat as stainless.
IMHO stainless is by far the best choice of material in this application. Stainless also has the best maintenance characteristics. Header coatings typically need recoat at periodic intervals. Stainless would probably have more problems with coating than mild steel because it has a higher thermal expansion factor.
Stainless will last indefinitely with only an occasional easy steel wool cleanup just for appearance. Unlike chrome which blues stainless can be polished back to original very easily. Mild steel that is coated rusts from the inside and eventually needs replacement.
Insulate the underside of the rear clip, it's been discussed at length. Another option for engine bay cooling is to put additional oval ducts in the license plate area like on the original Gulf cars. You can also put a SS shroud over the mufflers. Robert at RF has also worked out a temp controlled fan cooling system which has been previously discussed.
It would be interesting to see a temp comparison between coated mild steel, coated stainless, and bare stainless. With the advent of inexpensive electrical thermometers this should be easy.
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