Fender vent comments?

[Alan_Myers]

Hi all,

Before starting to cut metal, I'm looking for feedback about installing fender vents in a TR4 and would really appreciate comments from anyone whose done this.

Specifically, I'm considering doing something a bit different from the usual triangular "Shell Rally" vents right behind the wheel arch. Looking at the body work, it appears it would be relatively simple to install vents above the footwell and might give even better air exhaust from the engine compartment because it's higher and further rearward. I.e., the proposed vents would right next to the wiper motor on the LH/driver's side and would require moving the voltage regulator on the other side (which is gone from my car anyway, after an alternator conversion.)

From photos I've seen, it appears the Lemans TRS cars had an underhood vent arrangement something like what I propose doing.

There is a flange on the inner fender that would be ideal to tack weld in a "floor" for the vent. The baffle behind the front wheel would act as the forward "wall. A rear "wall" would need to be fabricated. Rubber strips such as are original on the baffle would be used to seal the vent to the outer fender.

I've figured out a way to use simple expanded steel to form a grill work on the fender. My main concerns are that cutting openings in these areas of the inner fender might effect body integrety, the area between the inner and outer fender will be odd shaped and that the "floor" of the vent will slope downward. Am I just over-engineering this? :rolleyes

Any other considerations? I'd be interested to hear everyone's thoughts. Quick, before I get out the nibbler!

There is a photo showing a mockup at https://www.triumphowners.com/640, in the "Bodywork" photo album.

/ubbthreads/images/graemlins/cheers.gif

 

[Guest]

Alan,
A plus for placing a vent in this area would be that you are opening the sealed are that the scuttle drains into. This could also be a minus. The idea of the location of this vent being high and rearward allowing more heat to escape may or may not be valid. The other option of placing vents behind the wheel arch would make the actual fabrication a little more straightforward in that the actual body of the vent tube would be out in the open and easier to fabricate/maintain. Cutting out the triangular area below and left of the master cylinder (TR6) and to the right of the washer bottle (again, TR6) would allow a straight albeit irregular path to this outside vent, ala the Corvette Stingray model. I opted instead to cut 13 louvers in my bonnet above my carb filters which has been proven with smoke testing to suck air in at speed and allow heat to escape at idle. Doesn't the Sabrina TR in the front office of The Roadster Factory have side vents, as I remember?

Bill

 

[LastDeadLast]

Courtesy of Darryl Uprichard of Racetorations:

and:

and:

 

[michalotti_tr]

Hi Alan,

Responded to your email on the Triumph mailing list (because I check my email first), but I'll restate here for everyone else. We seem to be following the same train of thought and are at about the same point with it (I might have pictures this weekend). I think you would have a 'cleaner' look if the interior portion of the vent were directly attached to the external fender and sealed against the inner, but that's just an opinion. Most people who do the "Shell Rally" vents use Herald grilles, but I think one or two horizonal chrome strips would compliment the body line better (again, just an opinion).

I'd say go for it, and post details as you proceed. If I start on mine first, I'll do the same /ubbthreads/images/graemlins/smile.gif

 

[bobh]

Alan,
The area in front of the windsheild is a high pressure area when you are driving. Remember the Cowl Induction setup on the early '70s Chevelles. Bill's experience illustrates this in that his louvers draw air in at speed.
I think the side vents are more effective. Air flowing down the side should help extract air from the engine compartment. I've read recommendations on exhaust systems that say the exhaust tip should be positioned so that the air flow helps to draw the exhaust out of the exhaust pipe. You can see this in a lot of race cars where they feed the exhaust out the side.

 

[DNK]

Bill is there a pic of your vents out there? i would like it to add to my picture stock.

 

[trfourtune]

bobh is right about the high pressure in front of the windshield. /ubbthreads/images/graemlins/iagree.gif to draw out hot air you need low pressure while DRIVING. just behind the front wheels is one spot, top of the hood just behind the rad is another. front of car is high pressure but as the air goes up over the hood (engine lid) there is a low pressure spot before air moves down towards the base of the windshield. get a large 0-1 psi guage or water manometer to measure the pressure spots on your car. run a plastic hose taped to your car running back to the guage temporarily on your dash to find exact low pressure or high pressure spots. many aftermarket hood scoops (general) are cosmetic only and are total BS(BROWN SUGAR to some). Drag guys have them up high to get above the low pressure and in "clean" air.
rob
as always,
what ever you do, think first,prove, then execute. /ubbthreads/images/graemlins/hammer.gif /ubbthreads/images/graemlins/cheers.gif /ubbthreads/images/graemlins/canpatriot.GIF

 

[Guest]

Hey DNK (do you have a nick name?),
Here is a pic of the louvers. Notice the red thingies inside, they are the three socks covering my velocity stacks. Usually have the three 3" K&N filters in place for the road.

Bill

 

[DNK]

Bill thanks looks great. Reminds me of sometj=hing Italian