Hi All,

If you remember i was pretty confused while writing my last post about my engine temperature rising after installing a cutout. Well I'm happy to say that the problem has fixed itself and i'm now running cooler again. I still don't know what exactly was wrong, but it's nice to know i can get on it again, even with the cutout open.

Had a couple quick stop light contests tonight and I'm proud to say I beat everything that was willing to play around with me which included an older rx-7 (non turbo), brand new style F-350 Power Stroke, mid 90's Chevy 1500 and a couple others that I can't remember off the top of my head. BTW, none of them were even close because they were falling behind fast after I layed into the throttle. This is with a soft launch too because I have the studded snow tires on and don't want to rip out the studs.

One question I have though is can anyone figure out how fast I can go at a specific rpm if I give you my rear end ratio? How fast would 5000 rpm in 3rd with an E40D and 3:55's be in miles per hour?

 

What size tires?
With the stock 235/75-15s it's about 117 MPH

 

31X10.5's but I'll get the exact measurement for you since I know that they aren't always the exact claimed size.

 

Don't bother, you can't measure actual rolling diameter. It's tabulated by the manufacturers at 680 revs per mile vs. 722 for the 235/75-15s. That makes your speed about 124 MPH.

 

Here's the reason I asked how fast I was going. I hit 5000 rpm on a long straight flat stretch in 3rd gear. I had a friend following me, he has a '98 Neon with the dohc and has added a chip, intake, and exhaust. We figure he has around 160 h.p. since it's rated at 150 stock. I figured that he had a faster top end than me so he could at least tell me how fast I could go according to his speedometer (knowing that speedometers are not accurate at high speeds) and I ended up leaving him in the dust. He says he hit 115 but I was pulling away. Does this sound right at all. I would have guessed my top speed was between 100-110, all I have added is exhaust, chip, and K&N panel filter with the airbox mod. If the tachometer read 5000 in my truck, what do you figure the real number would be, because I have huge doubts that this truck could hit 120+ without some serious modifications like heads, upper and lower intake, cam and those sorts of things.

 

5000 is about 124 MPH, here's the numbers:

5000 engine RPM in 3rd is 5000 driveshaft RPM which divided by 3.55 is 1408.5 wheel RPM.

1408.5/680 = 2.07 miles per minute
2.07 x 60 = 124 MPH

 

I calculated my speed to be 116mph @ 4,600 RPM's in 4th. gear, which is 1:1 (with 3.55's and 31"ers). I think that 3rd in an E40D would be 1:1. With a couple light mods, I would assume that 120+mph would be feasible, but I just ran mine up on some dead hwy, it had more but I didnt wait around for it. While most mods are tend towards torque for our trucks, HP mods would seem more logical.

 

I understand that much. Is my stock tach inaccurate at higher rpms making my 5000 rpm's an unreliable number?