OK so in October last year I got the car on the dyno at a dyno day. I made 3 pulls (Sorry I didn't get to log any of them) 1 on waste gate pressure (6.5 psi) and 2 on 14 psi


You can see it in the low boost pulls but it is the most obvious in the high boost pulls. The car laid over had at 5500rpm it could be felt in the car on the dyno (I can not feel it on the street or at the track). I did after this dyno day find the ground on the back of the drivers head was loose. But the car also ran 8.8 like this.

I plan to get the car on the dyno early this year and try and track down the issue. But places to start would be good. I will add. I had TR6 plugs on this dyno day. But had a similar looking low boost dyno graph with BREF7 plugs but I also had my Alternator die then.

Plugs were gapped around .022 AFR was around 11.5-11.6 on E85 and and 21 degrees of timing.

Let me know if you need anymore info

 

I wonder if the transmission is slipping on the dyno due to the extra weight of the rollers, but on the track it doesn't because the car is lighter than the mass of the rollers. Just a thought.

 

Doesn't seem like it to me as the car stopped torqing and just sounded a little off. If the trans was slipping I would think it would have sounded like it was pulling hard. It is hard to describe

 

Why does it do it on the dyno? What rpm does the car pull hard to on the track/street? There is something that is different on the dyno.

 

Well at the track I am only below 5500rpm in 1st gear and it pulls so hard and so quick that I just can't feel it. The car only drops 1000 rpm on the shifts so it drops from 6700 rpm to 5700 rpm.

Also hooking my car at 14 psi on the street doesn't happen

 

What you are seeing is the effect of a large stall converter on the dyno. All of the pull before 5500 is just converter slip. When it finally catches it is showing you what you are actually making. On the low boost pull, the converter is grabbing much sooner.


Ryan

 

^^^^^ And could have to do with the wg opening. Do you have a graph of the boost?

 

No graph of boost They didn't have a sensor for that there and I forgot to log the pulls.

But to do know at the track in 1st gear the car sees full boost before 4400rpm

I am just suprised that my 3400 Yank Stall goes that high graphs from a friend didn't look like that with the sae stall

 

If it goes 158 and the graph looks like that I wouldn't even think about the dyno numbers. I have had cars that have had ugly graphs that can have you chasing a problem that does not exist. Just to bring them to the track and have them run like an animal. Oh and for what it is worth I never had a high hp car with a yank converter show good dyno numbers. If you try to lock it at WOT like a Precision converter it will likely be junk afterwords.

 

I know I am not saying I am dissapointed with how the car runs at all. I am very happy with how it run for the amount of boost I am running.

I am just wanting to make sure there isn't an issue with the car.

 

its cause of that sweet turbo lol

 

My dyno sheet with the same converter/power.



If it runs good at the track don't worry about it.

 

this.

graph it based on mph and it will look "normal"

 

Yup, stalled autos should always be put over mph for a "nice" looking graph although plotted over RPM does show you how aggressively it comes up to it's stall speed.

 

Yup -

Lock up the converter and the results will be a LOT better.

 

I can't lock the converter in my TH400. Next time I will get it plotted over MPH

 

yeah you can replot that pull by mph also, do you have the run time files?

 

I don't have the run files. I might be able to aquire them.

 

390, 83mm comp, 92 turbine with 4L80e locked converter, 12lb's

 

With a T400 you always plot by mph, not rpm. Shows what going on. Then if it's a non-loaded dyno the boost can drop in the higher rpms because the roller is just free wheeling.
Here is mine by mph, nice long pull. Too bad the converter couldn't take it.