Video from pull https://www.facebook.com/rob.melcher...06577926032440

Was wondering if any of you guys dyno unlocked to help control boost spike?

Mine locked in 3rd with a manual boost controller gets a 6-7psi spike at 4800-5k area. Makes it pretty much impossible to run 24-25psi through 7k.

My boost controller is referenced off turbo and Wastegate is off crossing over pipe, 60 JGS open vent.

I'd like to get a 1k HP sheet, but at 943HP I was 26-28psi spiking and down to 21psi or so out the top.

I also tried hitting it really late in the rpm at 4500 and also tried really early at 2k, same results, just moved spike a couple hundred rpms apart.

Clearly on the streets their is no spike and their is about 1-2psi drop from 5k-7k. but I also don't do locked pulls either.

 

get a good controller that uses c02 to control spiking



as for Dynojet for the standard DJs theres no loading them

 

I load the dynos with the brake. Its horrible for the dyno but its the only way to load them to get a decent read out. Diesel trucks esp. at the very beginning of the pull, as in the same time you go WOT, apply the dyno brake for a second then release it, it will load the engine, produce spool and carry it throughout the pull.

I did the same on a 1000 hp turbo car. Brake boosting the dyno is really bad for the dyno brake but its the only way we found to do it. Brake boosting the vehicle on the dyno didnt work as well.

 

using the brake isnt the best option and if youre gonna do it make sure dyno owner agrees with it or your dyno session may end up costing you more then you wanted to pay

 

Yea, have to use the brake or a good/better boost controller. You get a spike because the turbo is outrunning the engine essentially. You want the turbo to get up to speed slower to get rid of the spike. Get to 3000rpm or whatever you want to start, have the dyno guy apply the brake or lock the dyno rpm in, go full throttle, get the boost up to where you want it (should only take 1-2 seconds), then have the dyno guy let go of the brake and there you go.

 

Turbo is out running the engine, so I just need someone to hold the compressor nut for a few seconds till the rpms get up?

So has that worked best for you to keep the boost Stable? Say 3500 rpms, apply dyno brake get 10-15psi online and green up the dyno and let it sing?

Yeah I rather not change up the whole boost control setup just to get a sheet, it performs fine on track where it really matters. I just want an sheet to back up the popular question of "how much power does it make?"

 

Yea, that worked pretty well for me, but a lot depends on your converter as well. If the rpm you lock at is lower than when you converter really comes online then you will still see a small spike, but much more manageable.

 

Well I have a manual lock switch and I just start locked. How do think the spike would be unlocked? I've never tried but it's a circle d triple with a 2800-3000 stall. I just don't know if it's going eat 100+HP

 

I always run mine unlocked. If your converter doesnt suck then the difference should not be much. Thats a good sign if your converter is not very efficient, if the power between locked and unlocked is drastically different.

 

I mean that's what I thought, I race with it unlocked the whole pass, so my weight to mph should reflect on the dyno.

Thanks for the info. There is a dyno day coming up and I was just about to give up on this local dyno.