Very true, but since hp is simply a function of torque and rpm, you could theoretically look at either value I would think. The dyno I was on had some ridiculous smoothing factor so the resolution sucked. It didn't even show the torque spike you get when you hit max boost.

 

Very informational thread. Thx to everyone for sharing

 

MBT on a dyno is very easy to see. All of the sudden the car stops making power. It will be 7-10whp one degree, the next is zero extra. Its still torque we are measuring, hp is just torque vs time.

 

how do you guys tune MBT on the dyno, do you do back to back runs adding timing in each run or do you hold at a set load and add timing that way and work your way up?

sorry to dig up an old thread but im in Australia and E85 is only just coming out at my local "gas station".

i have tuned cars on 98 but E85 is new to me

 

Judging by what Lucas just said a couple posts up I'd go with your first idea. Seeing as English Racing is like the E85 godzzzz

 

ahhh k, thats the reason i asked, ill get my AFR's set close on the road with conservative timing advancements for E85 road tune, until next wednsday arvo ill put her on the dyno and have a play,
ive been reading heaps of info on this site about E85 tuning, mainly in iTunes e85 topic,
im gonna try some of the similar AFR settings on my RB26 that you guys run with your 4G63's.
i cant believe on a stock motor you are running 25+psi, thats crazy

 

we do it pretty often on the stock turbo's around here on pump and E85

 

You can also hear the difference in tone in the motor when you get close to or at MBT.

I know it sounds like mystical magic but it's true.

 

That's gotta take some practice lol

 

Or you could simply use Virtual Dyno.

https://www.evolutionm.net/forums/8437968-post1.html

https://www.evolutionm.net/forums/7178814-post1.html

These are both good; I like the first one the best.

 

thats all well and good if i had an evo
doesnt matter ill work it out on the dyno, ill use low load runs so to go easy on it till i find MBT then try a high load run.

what sort of Exhaust Temps do you see with E85 at the dump pipe?

 

You can always go by bore size for a rough starting point. I am thinking this is for an RB? The Evo has 85mm, I am running 86.5 and have been as large as 87mm so I can say that the timing is pretty consistent. I know from experience that a 2JZ runs a few more degrees than we do typically.

Timing curve is the more important thing to watch I feel. Low at peak boost, tapering slowly to about 70% of full rev then up to 13 or 14* by 75* and in our case 18* or so out the top.

I have seen EGT as low as 1100 degrees F in a full pull at 35psi and as high as 1300*F at 38 in my car.

 

Track the 320 load range from 4500 to about 6000 and then track the 270 & 300

 

excellent thanks, i will keep that in mind, my RB runs a stock bore size of 86mm.
My tuning software works differently, works off a mixture of TPS airflow meter signals (x2 for twin turbo) etc.
below is a screen shot of a 18psi PULP run making 293kw
from left to right is how my car traces

 

In the Nissan world, TP = Theoretical Pulsewidth, not throttle position. TP is derived from an equation that accounts for MAF voltage, RPM, # of cyls, injection multiplier...I found that even on pump gas my RB26 liked a lot more timing than most evo's run. My E98 timing would be considered absurd on here.

Marshall