Ok, I received my DBB Black and the preload was basically covering half the circle on the rod. I've been reading and hearing people state they cut the threads and notch that bad boy down as tight as possible to increase spool (not sure of the other advantages). If I do this, would I have to be retuned or can I just tighten it down more and play? Any disadvantages of doing this? Thanks.

 

You don't want to tighten it too much or you might not be able to bleed off excess boost at higher loads.

 

it will help spool the turbo quicker but not by much. it will also raise the peak boost a few psi on the initial spike. raising the boost= new tune unless the car was tuned for higher boost and for some reason you turned it down.

 

I have a few questions for the OP: How are you controlling boost? What is your target boost level? What DV/BOV is on there now? This is with the 18#, or the 25# actuator?

I think that you should not be overly hasty. That is, don't just go out and lop a chunk of the actuator rod off. Approach the issue of preload gradually. Every combination is different. There is no fixed rule. So, first I would test the turbo as preset and shipped to you by FP. If upon testing you find spool to be a bit too relaxed for your taste then we can go about adjusting spring tension.

 

Qft!

 

With respect to trimming the length of the actuator rod on the FP 25# WGA...proceed with caution. I was tinkering around with an FP 25# actuator today after reading through your thread. I was basically curious as to how much could be safely cut off the end of the actuator rod on this actuator. If it was me I would be real careful with this puppy.

First thing I noticed was that you don't gain much more travel by removing the backup nut. It is really minimal. Maybe you gain a thread, maybe two threads at the max. Maybe for this reason, FP chose to employ a relatively thin backup nut on this actuator. Probably because they realized that a nut of normal thickness covered up too many threads on a rod with not too much range of adjustability to start with. So, yeah to get much more tension out of it you would have to cut it.

The thing is that you can't safely cut much more than two threads off the end of the rod which translates to only about 3/16" in length. Oh sure, if you dicked with it you could coax a bit more out of it.

For example, you could run a thread cutting die a bit further down the rod another 1/4" maybe. Beyond the last thread the cross section of the rod is no longer circular however. It has two flat sides. Also the threads end right before a bend in the rod. But you might be able to cut another 1/4" of thread onto there by using a die.

Another option would be to fill the hole in the flat of the turnbuckle which slides up onto the peg on the flapper valve's pivot arm and drill a new hole a tiny bit further down the flat on the turnbuckle. As a practical matter this would accomplish the same thing as shortening the rod via cutting it.

The turnbuckle fitted by FP onto the end of the actuator rod on the 25# actuator is relatively short and has a shallow threaded internal cavity. So, there is not much adjustability, or thread travel before reaching the point where the tip of the rod bottoms out inside the turnbuckle.

As you can see it will be a little more complicated to shorten the overall length of the actuator rod on the FP 25# actuator in comparison to the relative ease with which one could modify the FP 18# actuator.

PS: I just purchased a new FP 25# actuator. I will be installing it onto my FP Red soon. I will test preload and if I can't get enough preload out of the thing then I'll start to tinker with it. Presently my turbo has a 18# FP actuator on it. As delivered the FP 25# actuators actually have been reported to go full open by 18# with zero preload. (18# PSI full open at zero preload seems kinda wimpy for guys that want to be setup to run over 28 PSI of boost or even over 32 peak). At any rate, I will keep you posted. Good Luck!

 

Thanks for the suggestions, I'm currently on SD, ecuboost, 30 psi, 25#wastegate, but 93 octane. It spools pretty good since I'm on a 2.3L but if I can make it spool any quicker it would help. I may just try to tighten it down more than it is and see if I can tell a difference and just leave the length like it is.
Thanks sparky for checking and for the info, now it all makes sense to me

 

Yeah, tighten the turnbuckle down some more before resorting to permanent modifications with irreversible consequences. Use up the full range of the actuator's designed-in adjustability before attacking it with a hacksaw or cutoff wheel. Tread with caution.

 

I asked Robert @ FP this exact same question and this is was his response,

"That is fine, so long as the preload isn't more than about 3mm or so."

 

So how do you know when you need more preload? Or is it someone one must test and see if it makes a difference? I put a gt2871 turbo on my rsx and it always drops to 15psi at redline. When i turn up the boost controller up the boost goes up in the midrange but always drops at high rpm no matter what.... would this mean i should preload the actuator more?

 

That is what he said? Really? I find that reccomendation to be pretty doubtful.Three millimeters converts to roughly 0.1 inch in linear measurement, doesn't it? Which as a practical matter, works out to be only one and a half complete rotations of the turnbuckle. So, is he saying that you can only rotate the turnbuckle 540* in either direction? Hmmm......

What did he mean anyhow when he stated that the preload shouldn't be more than 3mm? Shouldn't we be measuring spring preload in PSI, or BAR? Someone is smoking high quality foliage.

 

Any updates on your test? I actually have both actuators as well, the 18 psi on my evo 9 turbo and the 25 psi on a new fp black that I just purchased. On the 18 psi I did like 6 half turns and that gave me like 15psi, I left it at that, but if you go the fp web site there are 3 videos that show the proper preload. On my FP black I check the preload and it was set like half way, 6 half turns. I my self will be putting more preload to it, but I wanted to know how your test went so that I have an idea on how much preload I should put on my.

 

Hmmmm. Yes, I was going to do a comparative empirical test pitting the FP18# vs the FP25# on my 64mm Red. However I never got around to doing it....sorry. I actually traded my new 25 pounder to another board member for his FP 18 pounder. I had shortened(cut)the actuator rod so much on my original 18 pounder, that I could not adjust preload down to a level under 25#. LOL

 

This might sound crazy, but has anyone ever seen wastegate preload cause a loss of spool? I know someone who preloaded his wastegate. It allowed him to hold higher boost (reduced taper) but the turbo didn't make full boost until 6000 rpm (FP Black). He took some of the preload off and it started making full boost at 5000 rpm.

I have another car with an FP Red that did not make full boost until 6000 rpm also. The wastegate was seriously preloaded before we put the turbo on the car. We have checked all other reasons for poor spool - boost leak, turbo damage, exhaust restriction etc. but haven't found anything wrong.

 

Hmmmm. In the two cases you bring up, how is boost being controlled? I mean, is it MBC, EBC, Hybrid, ECU/BCS, or whatever. Also, are we talking stock actuators, or aftermarket WGA's?