On an NA car the differences are very little between 3rd and 4th usually. With forced induction the RPM ramp is much more pronounced and the torque is higher yielding so doing an FI car in different gearing other than 1:1 can yield very different results.

 

4th is the 1:1 gearing and true gear all dyno's should be done in no matter what the car/truck/suv/etc.

When NA though it's not very much different unless using some super tranny that has taller gear sets to allow for higher hp controllability.

Most stock trannys don't have this huge varience... again though as you stated the rpm ramp and rotational force being applied is what's being measured. Thus for FI guys it's very important to do the pull in the 1:1 ratio for the most accuracy and true results. Lower gearing will yield higher results with them due to the hightened ramp... On an NA car the difference from pulling in 3rd to 4th may seem like a lot but it is still a nice long ramp that the dyno can accurately calculate off of.

 

oh yeah. i read in a dynojet instruction manual(downloadable on the web somewhere) you HAVE TO dyno in 4th. having the 1:1 ratio does make sense as the variables in finding hp are distance, time, and rpm, and if these are the main variables(i know, not all the vars) used then having your rpms at a higher range of mph will see different results. and then as boe said, accurate measure of the engine as there is no torque multiplier.

hey boe, what kind of difference have you seen between dynoing in 3rd and in 4th?

 

exactly!

 

Well... looks like the weight was somewhat accurate on this one. I got on a scale this weekend and the weight of the car was 1280Kg(2821lbs) + my weight(120lbs) = 2941. I weighted the car with 1/4 tank.

I have to add my weight because it was late at night and the station was closed. So I had to get out of the car to go have a look at the computer screen

 

I have RRM Short ram intake/HEaders/Piggy back/ligthweigth pulley does anyone know how many wheel hp and wheel tq i might have? someone please let me know

 

Don't want to be rude, but this is a thread where you post your dyno graph. Not where you ask questions You should dyno around 115-120

 

^ +1

Once you get past the neophyte tuning mentality, you would know that there is no way to calculate how much power you will get by adding up your mods or any equasion like that. So the best answer to that question is that you will have somewhere between 100 and 120 whp and 110-130 wtq, but that's assuming you didn't get too open of a header, in which case I've actually seena loss of torque.

But seriously, the only way to tell is to pay the $75 and get it dynoed.

 

My latest results with piggyback:

 

Very nice Blaze. The curve is very nice and stable, and you have a lot of torque a long way, then the max hp hits right about where you want to shift. What other mods do you have, or is that just with the piggy?

 

blaze dont forget to put type of dyno and conditions up as well... but nice pulls

 

are you letting it hit the rev limiter? you gotta end the run before that or you get that spike you see at the end.

 

Thanks. On that pull the mods were:

Sri, Kamikaze header + dp, cat-back, piggyback

That pull was done the day before I installed my bored intake manifold. Now I'm just waiting for nice weather to quantify the gains of the IM.

I'm using the Auterra Pda dyno.

Yeah I know I should stop before but I always want to see exacly what's going on... so I figured most users would know where the rev limiter kicked in.

 

i'm getting on the dyno tomorrow. i'm so excited! i'll post my results. (right now i've got an exhaust leak and some minor odds and ends that will effect the results a little bit but hey, after all it is just a set of numbers) i'm looking to get a baseline before i boost.

 

^Nice, can't wait.