Can a cap takeaway from performance?
#1
Can a cap takeaway from performance?
Hy everyone,
I am planning on a long road trip next week and I am considerig taking the fiberglass cap/shell off of my truck to improve gas milage and performance. I'm guessing I might only gain 1mpg but anything helps nowadays. Can anyone confirm improvements in mileage or performance without a cap on.
Is there any reason why I should leave the cap on? Can anyone recommend a proper way to store the cap off the vehicle?
Thanks, BB
98 F150 SCAB- 4.6 - avg mpg now @17.8
I am planning on a long road trip next week and I am considerig taking the fiberglass cap/shell off of my truck to improve gas milage and performance. I'm guessing I might only gain 1mpg but anything helps nowadays. Can anyone confirm improvements in mileage or performance without a cap on.
Is there any reason why I should leave the cap on? Can anyone recommend a proper way to store the cap off the vehicle?
Thanks, BB
98 F150 SCAB- 4.6 - avg mpg now @17.8
#2
I think that leaving the cap on would be better for gas milage b/c it decreases the amount of drag caused by the bed/tailgate. If you take the cap off then you whould have to put the tailgate down or remove it to get better gas milage. I actually found that I used less gas when I put it on, just my opinion though.
#3
the wind does blow
thanks for the reply, my friend tells me the same thing about drag . My reply to him is that the truck is tossed around quite a bit with a good crosswind and the weight of the cap can not help either.
on my previos truck, 96 f150 with a 4.9 inline 6, I felt that I had better acceleration without the cap on and about 1.5mpg increase.
on my previos truck, 96 f150 with a 4.9 inline 6, I felt that I had better acceleration without the cap on and about 1.5mpg increase.
#6
I can't speak to the cap / no cap issue, but there is some scientific evidence that pretty well refutes the tailgate down / missing theory. The best evidence I've seen was when GM ran a modified S-10 a number of years ago at Bonneville. Since they were going for a speed record, low drag was critical. They actually ran the truck with a tailgate and a partial tonneua cover - over the rear half. This combination was arrived at after man yhours in the wind tunnel - and under very controlled conditions. There, that ought to spark a heated debate. Hope that helps!
As for the cap, I would suggest that if you fill the bed up with a ton of irregularly shaped items, a cap would probably be more aerodynamic. Oh yea, and there's one other draw back to running with a tailgate down. The two cables that keep it from dropping right on your bumber take a whupping on every bump,. Sooner or later they're going to break. How much is that worth?
As for the cap, I would suggest that if you fill the bed up with a ton of irregularly shaped items, a cap would probably be more aerodynamic. Oh yea, and there's one other draw back to running with a tailgate down. The two cables that keep it from dropping right on your bumber take a whupping on every bump,. Sooner or later they're going to break. How much is that worth?
#7
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#8
Yes, when I owned an 87 Ford Ranger I bought a cap for it for when I moved to New Hampshire from California. From my own personal experience with that particular truck I can tell you that I got WORSE mileage WITH the cap then I did without. I don’t recall just how bad but it was a few mpg. Now that was a 4-banger getting something like 25 – 27mpg without the cap.
You could also feel the drag affect with the cap on as compared to being off. When the cap was not on I had a soft tonneau cover on it and you could feel it move much easier though the wind when it did NOT have the cap.
A truck is already going to have a lot of drag on the rear-end because it is flat (tailgate) when you add a cap you will increase the drag affect. The best gas mileage is achieved with a tonneau cover on and tailgate up (closed). Both a cap and an open bed with the tailgate down cause more drag.
You could also feel the drag affect with the cap on as compared to being off. When the cap was not on I had a soft tonneau cover on it and you could feel it move much easier though the wind when it did NOT have the cap.
A truck is already going to have a lot of drag on the rear-end because it is flat (tailgate) when you add a cap you will increase the drag affect. The best gas mileage is achieved with a tonneau cover on and tailgate up (closed). Both a cap and an open bed with the tailgate down cause more drag.