DynoFlash

iTrader: (91)

I really thought this dyno comparision was fascinating

Here we have a Evo IX with Stage II and fmic with SMC alky kit and stock turbo with 93 pump gas - also 02 housing by ebay

I wanted to see how the car reacts under varying boost levels

As you know I have been suggesting that customers consider more modest boost levels to err on the side of engine long term reliability on daily driven evos with stock motors

I dialed in this customer's car at 28 psi - no knock - typical a/f and timing

Then after speaking with the customer decided to turn down the boost to 24 for the street and as a good daily boost level

I am very fascinatd to see that the stock turbo is basically maxed out on his set up after 6,000 and that no additional power is realized in the upper rpm range with higher boost spike down low as no matter how high the boost is set it falls down to the same level by red line

NOTE - his car uses a Hallman MBC - with a EBC with rpm dependant duty cycle adjustment perhapse we could have pushed the turbo harder on the top end - or with an acutaor upgrade

The dyno sheet is very interesting though

mplspilot

iTrader: (7)

Yeah, i love my torque down low.

zbomb

iTrader: (48)

I think that the massive tourque spike of the high boost run is one of the things that makes stock turbo'd evos running on meth or race gas so much fun.

DynoFlash

iTrader: (91)

Nevertheless - food for thought !

The great thng about the car in question was that it had the in cockpit hallman controller and the car was carefully mapped at both 24 and 28 psi of bost


ALL the customer needs to do when he wants the low end TQ is dial up the boost and then under more normal conditions when he wants he can run 24 to take it easier on his equipment. The ecu is mapped for all boost levels from 20 psi to 28 psi so the cutsomer can run what ever boost he wants.

My point is merely to illustrate how the turbo reacts with varying bost levels

Al

mplspilot

iTrader: (7)

^ It is a good point, you're right.
Thanks for the graph!

I think i'll start showing the graph to people that use the line "man, why are you running so much boost, you're just pushing hot air", cause they heard it somewhere, and think they sound smart when they say that, but don't know what the hell they are talking about.

Jeff_Jeske

iTrader: (66)

I would love to autox that car at 28psi!

I can see why modded 9s are going through clutches soo fast!

Ralph

iTrader: (19)

28psi, 24psi - this is the peak boost. After the initial peak, at least in my car and others I've tuned, the boost drops and eventually meets at a certain RPM.. no matter what.

More boost low end, more torque.
Top-end identical boost..... same hp/tq.

DCsleeper

iTrader: (11)

Al,

Interesting graph, but I don't think that this represents how the turbo reacts. It is more how the Hallman boost controller works to control the boost. As you stated in your original post, the result could be much different if the setup used an EBCS or varied the boost duty cycle by rpm. I woud be interested to see an example utilizing this capability to hold the boost throughout the rpm band. Currently, I can hold 22-23 psi easily on my stock 8 turbo by varying the duty cyle from 65 to 74 percent throughout the rpm range. I am interested in what the stock turbo is actually capable of, I think most people jump to larger turbos before maximizing thier current setup.

I have just recently started tuning my setup with water injection. Hopefully, I will answer allot of my own questions soon. I am interested in how much the use of water injection can counter the increase air temperature caused by pushing the turbo obviouly outside of its most efficient zone.

crcain

I hate it when I hear people get tuned for 23 psi then stop....

What happens if you overboost somehow accidentally?

All tuners should be mapping customer cars for more boost then the customer intends to run I think.

a) it is more safe to have a map which can handle extreme conditions
b) you can let the customer choose what feels better (23 or 32 or whatever)

I dont care if you are running -4 degrees advance, it seems to me the car should be mapped so it is det free in every scenario.

DynoFlash

iTrader: (91)

Maybe you did not read my posting very carefully


We mapped the cafr to 28 psi where we felt the maximum safe boost level was reached with the pump gas the customer had

Then we turned down the boost and mapped it at 24 psi also

The car is mapped to run anywhere between 20 psi - 28 psi

I am sure it could handle 30 psi or more on race gas with no problems

TouringBubble

iTrader: (2)

I think he's agreeing with you Al.

rr06rs

iTrader: (6)

How does this work when you're running off of 1 map? Or is it just that it's so conservative and rich that it is safe enough to run it that high? So in reality, if you're running 28psi, you're running the tune at it's most effective level. Yes, you can turn it down to 20 but wouldn't the tune be very rich and mild as far as timing goes and would not make the same power as someone that was tuned for 20psi specifically?

DCsleeper

iTrader: (11)

It really isn't that difficult to tune to different boost levels on the same map. When you adjust the boost level that much, it puts you in completly different load cells at the same rpm. The ECU can even interrpolate between the two cells giving you even more resolution.

I am sure a good tuner can easily map out a tune for several levels of boost very quickly. I understand the principles but do not have the experience to do it quickly. It takes me forever to slowly and I mean really slowly make changes and work through the map.

good post Al, thanks for the info. Looking forward to may more.

SlowSportSedan

The torque is good from a roll race though... Thats whats awesom about spiking that... those numbers seem a bit low though, unless its a tiny meth nozzle.


torque is daily driver fun, better than hp.

evilempire76

iTrader: (42)

That what I was wondering as well. AT what point would it become to rich to where the car is experiencing bore wash from the water / meth injection spraying to much?