stevebez

Been thinking alot about dyno numbers and real world performance and would like to see if this experiment is possible.

Since at the strip we accel through 1st,2nd,3rd... we go through basically 3 cylces from idle through to redline , albeit very fast in first somewhat slower in 2nd and then quite a bit slower in third...

My point?

Well on the dyno we concentrate on 1 optimal cycle to avoid the dreaded heat soak. Well I think this is our biggest problem as we are not investigating the heatsoak issue well enough ... lets say I am more interested in the power the motor is making as I cross the finish line than the power I am making in optimal conditions... 4th gear pull does take longer and to some degree replicates the h/s issue but not enough in my opinion.

This is where a mod like the Renntech SLR I/C's would be tested well. Saying they give an extra 30hp in optimal conditions is handy - but if they give me an extra 50+ hp across the line then we have something very worthwhile...

Alternatively I am trying to establish the curve of IAT's from standstill to lets say 150mph...

Timeless

Waiting for the smart people to reply.

Zod

Just curious steve do you have any numbers to show, any data to back up the heat soak issue from your side?

Are we talking about stock cars, or modified ones with big *** ASP pulley(one of the biggest you can get)?

and have you dynoed her?

joshd

The biggest problem with replicating real word conditions is that short of a wind tunnel, there is no way to get enough airflow to the front of the car to simulate 100+ MPH worth of air. Therefore a run through the gears 1-4 will cause the car to heat soak much more on the dyno then in the real world. You basically need to be a car manufacturer with millions of dollars to spend in R&D to really perform those types of tests. And even then, the dyno is still just a tuning tool, not really a real world simulator ... that's why they perform highly instrumented road testing/tuning in various conditions.

Zod

or in short you data log while driving,hence showing DATA results!
Before you can say heat soak is an issue

Ofc you can expect to maybe get the car hotter on a dyno when doing back to back runs, due to no providing the car with the AIR it needs
thats why you get a big *** fan
open the hood
and let the car cool down before the dyno run

all of this is still not the same as driving at speed
and if you suffer from the so called ''heat soak'' issue on a stock car, that is most likely pump related! i.e your pump is dying and needs to be upgraded to the newest one they have (which works fine!) and should be under warranty

stevebez

I have not dynoed my car, but what I am more interested in is how do we evaluate a mod like SLR type i/coolers when we cannot replicate the problem properly on a test bed?

The road test is simple but difficult to find the open safe stretch which is "legal" and just hook up a data logger, drive it to 150mph as see what happens to IAT's and coolant temps.

When I did the VMax event a while back the car's temps went really high and there was no sign of plateau in IAT's or collant temps on the run which maybe lasted ~25 seconds or so...?

This was before I put on the CM90/Code3/W220 rad. But now I have no way to determine if its working right without doing the same event again. I guess this is the only way to test this and perhaps the split circuit type mod...

My real point is max power under ideal conditions is much less relevant than what your power is on your 4th consecutive pull for example....

ChicagoX

As mentioned, there is no way to replicate real-world airflow on a dyno.

My car, equipped with a Johnson pump, will lose up to 30RWHP by the third pull. This is with a 20 horsepower fan over 5 feet tall !!!

Steve - I agree that road testing is the best method, but as you correctly pointed out, where are you going to do a 4th-gear pull from 40-175 MPH?

In your case, you would probably want to datalog a driving 'loop' that can be replicated. It would preferably contain both stop-and-go as well as some high-speed blasts.

Zod

There you go
https://mbworld.org/forums/showthrea...t=logging+data

and thats just with evosport cooling kit
secondly look where i come from...i studied in the Uk, there is no SUN, just rain and cold!!!
Freaking 55k engines would be so bad *** there!!!! n you would have no traction
you should be fine, stop with the theory crafting allready , reall world testing is what you want!

Hope this helps you

ChicagoX

I use Auterra's dyno-scan, running on the laptop. The sampling rate is much better than some other competitive products, and it has some cool 'dyno' features that give better data that something like a GTech pro RR (which I returned because it wasn't repeatable like this setup) for pre- and post-mod comparisons.

LINK TO DASH DYNO

The above link is to the P&P hardware solution. If you don't want to do the laptop-in-the-passenger-seat thing, it's a nice self-contained piece.

You can export files into CSV to send to your tuner or shop as well.