prollyben Posted March 14 Report Share Posted March 14 Was wondering if anyone has attempted this or something similar? Taking the truck cross country. Was looking for something that would increase highway cruising speed but still have good acceleration/low range for mild off roading. Apparently the s15 6 speed will bolt up to a KA meaning it should theoretically bolt up to a napz with the same bolt pattern. Assuming I would have to modify the k member Quote Link to comment
]2eDeYe Posted March 15 Report Share Posted March 15 I would be looking for a frontier 6-speed. Quote Link to comment
datzenmike Posted March 15 Report Share Posted March 15 15 hours ago, prollyben said: Was wondering if anyone has attempted this or something similar? Taking the truck cross country. Was looking for something that would increase highway cruising speed but still have good acceleration/low range for mild off roading. Apparently the s15 6 speed will bolt up to a KA meaning it should theoretically bolt up to a napz with the same bolt pattern. Assuming I would have to modify the k member Stick with the original transmission. If top speed is say 80 MPH this is because this is as much air the 720 can push through. Increasing the over drive ratio will lower the RPMs so it makes less power and does less work. There are practical limits to gearing and air resistance increases with the square of the speed. If it takes x power to go 40, it will take 4x to double to 80. Quote Link to comment
prollyben Posted March 16 Author Report Share Posted March 16 On 3/15/2024 at 9:45 AM, datzenmike said: Stick with the original transmission. If top speed is say 80 MPH this is because this is as much air the 720 can push through. Increasing the over drive ratio will lower the RPMs so it makes less power and does less work. There are practical limits to gearing and air resistance increases with the square of the speed. If it takes x power to go 40, it will take 4x to double to 80. Was looking to upgrade the cam and maybe port for low end. The truck will be on the highway for long distances, was looking to keep gas mileage up and engine wear down. Just want to know if it would even fit or is possible with the s15 trans or if there’s a better alternative Quote Link to comment
datzenmike Posted March 16 Report Share Posted March 16 Porting allow better breathing at higher speeds where power can be made. Same with cam, the stock one has the best for all speeds and best economy. The '84 already has a 5 speed with a 16.7% over drive. The S15 is around 23.3%. An over drive does not mean you can go faster than forth. You can if you make enough power but here a car maker will simply change the differential ratio to increase gas mileage and the top speed and the over drive simply lowers RPMs at cruse speeds. What's your top speed flat out in your 720? in 5th? Would 80 MPH sound close? 720 with 3.545 differential and 25" diameter tires and stock transmission is revving 3,811 RPMs in forth and 3,175 in 5th at 80 MPH With an S15 6 speed in DD 5th still 3,811 RPMs and 2,923 RPMs in 6th at 80 MPH Assuming that the Z24 makes maximum power somewhere above 4,000 RPMs then if 80 is top speed in 5th at 3,175 RPMs then likely you would go faster (not a lot but faster) in 4th at 3,811 RPMs where you are making more power. It follows then that the S15 transmission in 6th at 2,923 RPMs you would actually go slower than the 720 transmission. The S15 probably makes about 50% more HP than the Z24 so it can make use of the 0.767 or 23.3% OD Quote Link to comment
Icehouse Posted March 17 Report Share Posted March 17 On 3/15/2024 at 6:21 AM, ]2eDeYe said: I would be looking for a frontier 6-speed. Isn't there only a 6 speed for the VQ? I Thought the 4 cylinder was only available in 5 speed? 1 Quote Link to comment
bottomwatcher Posted March 17 Report Share Posted March 17 16 hours ago, prollyben said: Was looking to upgrade the cam and maybe port for low end. The truck will be on the highway for long distances, was looking to keep gas mileage up and engine wear down. Just want to know if it would even fit or is possible with the s15 trans or if there’s a better alternative Easiest is like a 79 280zx 5 speed. Drops right in with a super high overdrive of .7 something. My 4x4 720 with 4.37s would cruise at 80 mph at 3,000 but only on flat ground "Florida". Any kind of incline required a downshift. You end up with a much higher first gear too. If you drive your truck like a car it is good. If you want to do truck things like pulling a trailer is sucks. Plus my 280 trans never lasted very long doing truck things. Quote Link to comment
datzenmike Posted March 17 Report Share Posted March 17 with close ratio 280zx 5 speed in 5th at 80 mph... 2,839 so again will the engine make enough power at 2,839 RPM to push through 80 MPH air????? Quote Link to comment
bottomwatcher Posted March 17 Report Share Posted March 17 4 hours ago, datzenmike said: with close ratio 280zx 5 speed in 5th at 80 mph... 2,839 so again will the engine make enough power at 2,839 RPM to push through 80 MPH air????? Barley. No headwind no incline. Did have a webber and I forgot you have to swap the front trans housing to fit the naps engine. Quote Link to comment
datzenmike Posted March 17 Report Share Posted March 17 Yeah the close ratio won't get much use unless on highway. Quote Link to comment
Madkaw Posted March 24 Report Share Posted March 24 These trucks did come with 3.9 gears which are highway friendly . Not sure what the rpm’s are at 80 , but they would have to be above 3000 and that would be needed to fight the bad aerodynamics of these trucks . Peak power in a stock NapZ 2.4 is at 2800 rpm’s Quote Link to comment
datzenmike Posted March 24 Report Share Posted March 24 Torque is 130 at 2,800. Don't know where the peak HP is. 1 Quote Link to comment
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