Here's what the G-tech Pro Competition had to say about all of these little mods. The red is stock + Nismo CAI only. The green is the addition of the ram and heat shield, and the blue is with the fender liner holes blocked.

Not shown is the speed in this comparison, which is approx. 35-40 mph. Further up the graph, above 50 mph, the blue line crosses above the green until at peak HP, in 4th gear at about 85 mph, I got over 3 RWHP increase with the vents blocked.

 

Why is the rwhp showing up so low? It should be at least 20-30 more.

 

Ah,

I was waiting for someone to ask that. Good question.

Part of the reason that the number seems low is that the car is moving, therefore incurring drag. In this respect, the G-tech is a better guage of a car's overall performance than a dyno.

The second reason for the low numbers is that for these runs I put in the gross vehicle weight - and did not add weight of the fuel or my fat a$$.

I have another series of numbers with the weights adjusted, but I didn't have the third (blue) run (the landfill was closed on Sunday) so it it would not have been complete for the illustration I was trying to make.

Regards,

Roark

 

You can dramatically reduce the variability of the car's weight by putting the car into an easily reproducable state and weighing it. For example:

Fill the gas up to full (as this is the largest weight variable), top off the other fluids, and make sure you have no cargo in the car (unless it's consistently always there). Then weigh the car. This state can always be returned to by topping off your gas and fluids. No need to weigh the car everytime, as it's pretty safe to assume the car weighs the same if you follow those procedures. You might want to weigh yourself, though, before each run.

I follow this procedure with my G-tech, and it has provided me with accurate and extremely reproducable results with no need to re-weigh my car all the time.

 

Yes, that is easily reproducable, and if that is your baseline procedure, then you will have accurate results for HP/TQ.

But a full tank of gas is not ideal for testing your times. I doubt I could get 14.2 in the quarter mile if I used a full tank. I've gotten a shade under 14 by always trying to have less than a 1/4 tank of gas during my runs. Remember, premium fuel weighs about 7 lbs/gallon. That's over 100 lbs diffence between full and 1/4 tank.

Whatever procedure works is great. Just plan and execute your baseline and reproduce it for subsequent runs and you will have exellent results.

I take 8 runs for each test. I know (because the G-tech shows it) that there is a slight grade in the strip I use to test. So I take 4 runs (2 in each direction) with the G-Tech calibrated to actual weight (if possible.) Then I repeat the process with the G-Tech calibrated to GVW. I compare the averages of the two sets of runs against the previous set taken before the mod to make my determination on the effectiveness of the modification.

I always set my tires to 32.0 ft-lbs. and check them between sets of runs. The temperature sensors in the rims are not that accurate, so I use a digital tire pressure guage.

Also, I only do my runs when the ambient temperature is between 75 and 85 degrees F. That mitigates any error introduced by colder/denser air vs. warmer air. I'm running shy of those warm days where I live, so my next mod (UR Underdrive Pulleys) may not get tested right away.

One last thing. The G-Tech does not store things like ambient temperature, wind speed, so it's a good idea to keep a journal of your runs with as much detail as possible. When you go back and look at all of the files of your runs, it can be confusing what runs are for what mods.

Roark

 

A couple of guys asked me to post the dimensions of the template I used to create the ram. Here you go.

 

nice info....thx

 

Thanks Roark! Great info!!!

 

Excellent DIY project info, thanks!

 

Great post Roark! Excellent job on this project.

 

Thanks everyone for all of the positive feedback.

I'm making two more of these for guys on the forum that want them. While I'm at it does anyone else want this kit? I'm asking $70 for the ram and $50 for the heat shield (or both for $110) plus shipping.

Only serious inquiries PM me please. I'll be fabricating these this week.