Fuel

Hamilton Cams said:
Just got a call from the engineers with their final recomendation factoring for alloys, cost, and durability.


First the stock numbers. THe OE 5th calculates to around a .745 overdrive. So with a 30.5" at 70mph you will be at 2040rpm with 3.55's and 2356 with 4.10's. With our .67 gears, you will be at 1830rpm with 3.55's and 2088 with 4.10's.

I wanted to focus on fuel economy but also focus on driveablility. I think this ratio will be a good mix. For some people 1830 will be lugging at 70mph with a load. For this to work well, you will have to have a conservative turbo, injectors and tuning. There will be a little more of a gap to 5th, but nothing unbearable if you use a few more r's up in 4th.
Conservative setup, a cam designed to maximize airflow at 1800-2200rpm and I think we will have a winner!

What are your thoughts on these ratios? I know they will not make everybody happy, but I think they are a great compromise and will work well for most.

Zach
Click to expand...


I thought you were going extreme? Towing will not be a problem with a .675 and 3.55's
I can tow with my 6.7L with 3.42's and a .625 OD, and taller rubber than most of the older trucks run.


Now, since I mentioned that, it might be a pretty tall gear if you have 35's and 3.55's or something, but for those of us with closer to stock tire sizes, I don't see any issue towing at those RPM

Chris
 
I'm very interested in the new 5th gear. its exactly what my brothers 12v with 4.10's needs
 
Hamilton Cams said:
Just got a call from the engineers with their final recomendation factoring for alloys, cost, and durability.


First the stock numbers. THe OE 5th calculates to around a .745 overdrive. So with a 30.5" at 70mph you will be at 2040rpm with 3.55's and 2356 with 4.10's. With our .67 gears, you will be at 1830rpm with 3.55's and 2088 with 4.10's.

I wanted to focus on fuel economy but also focus on driveablility. I think this ratio will be a good mix. For some people 1830 will be lugging at 70mph with a load. For this to work well, you will have to have a conservative turbo, injectors and tuning. There will be a little more of a gap to 5th, but nothing unbearable if you use a few more r's up in 4th.
Conservative setup, a cam designed to maximize airflow at 1800-2200rpm and I think we will have a winner!

What are your thoughts on these ratios? I know they will not make everybody happy, but I think they are a great compromise and will work well for most.

Zach
Click to expand...



I would like it lower myself. But I will take one anyway.
 
i am interested in a higher ratio 5th gear. the cam sounds cool for one of the daily drivers i have. what about one for a 4bt?
 
In the origional post you mentioned the possible price ranges for the cam, but what about the 5th gear? I need to know how much to save up. I know you cant give anything concrete until you see the demand curve and what not, but do you have an educated guestimate? Thanks...

-Billy-
 
I am still waiting on the prices for the gear. We are about to start production on a few test pieces. After testing we will figure out a more concrete number on the gears.

Zach
 
bump for this. also a quick question. if i already have a gear vendors. will have the .67 5th gear lower my double over drive even more. right now my final drive is .58 with a 2.06 rear ratio.
 
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