Beats on the street and 1/4 sometimes. I like to hit top speed on the car

 

Street used to mean smaller turbo for good response/bottom end (ie: full/green), drag tends to mean larger turbo focused mainly on topend and peak power. Then again they're so many 500-600+ HP 'street' evos around now I don't know what street means anymore.

 

EvocentriK: What DV/BOV is fitted? What cams? Do you have adjustable cam sprockets? Is it the stock WGA on the turbo? Have you established what the preload(spring pressure) level is currently?

 

This thread is becoming more and more interesting. Presently, I have a JB Red on my RS(stock block) and am not at all satified with the spool up or the lack of transient response. I wanted to order a BB Full, but picked up a used 3B instead. Now after reading the responses on this thread, I am having second thoughts about installing the 3B fearing that I wil not be satisfied with that turbo's spoolup either. I may end up selling the 3B and ordering a new BB Full after all. Aw Krud

 

Synapse DV, Tomei 260's, Yes - Tomei cam gears at +1.5/-2.5, stock WGA preloaded a little harder at ~11psi, boost control is via ECU w/ 3-port, self tuned.

Sounds like you're in the same boat as me but you think your yet to be fitted turbo may be too big, I think mine may be too small. I think BB Full is looking appealing but having a full already, is it worth it is my question.

For me to make the decision, I really need data from Chad at CBRD (or anyone else who's got it) on transient response of BB Full vs JB Full, and comments from anyone who's used them both or has the BB Full.

 

This is such a noob question but would using a higher pressure actuator ie: 18psi or so, increase the responsiveness of the turbo?

 

CBRD offers a HD WGA option. I personally haven't tried their actuator, so I can't comment on it although I am sure it's good. I have used and recommend the FP 18# HD IX actuator. Additionally, Turbosmart and Forge also make actuators for the IX frame.

As far as the MHI actuator is concerned you can mod it to perform better than stock. A rough test is to grab hold of the actuator rod and pull on it with your forearm strength. If you can pull the rod axially away from the cannister about 1/2-3/4"...then you need to adjust it tighter.

That 1/2" travel corresponds to the first coil of the actuator spring compressing and allowing the flapper valve to ride up off it's seat at 7-10# boost. So you are probably already bypassing some exhaust flow out through the bypass port at those low boost levels. This is killing spool up.
As a rule of thumb if you want to optimize spoolup, you want spring pressure adjusted to about 3# under your peak boost level. The stock actuator is good if modded for peak levels in the 18-22# range. But, if you are currently preloaded to only 11#, then it should spoolup better if you increase spring pressure up into the 14-16 PSI range.

 

How do you perform the mod? I can pull the actuator to pretty much full extension with some effort. I think they are only 0.9 bar stock.

I use a 3-port though so theoretically the actuator shouldn't be seeing any boost until over 3500rpm since I run 100% WGDC until that point in the first 3 gears. For that reason I don't think it would affect spoolup per se.

Higher in the rev range though, where the WGDC table has values much lower than 100%, I am wondering if running a stiffer (or modified) actuator with a spring pressure of ~18psi say, would improve transient response? If some boost is being bled to the actuator at those times, say at 4500rpm in 3rd I'm at 69.5% WGDC, shouldn't having a higher rated actuator essentially not move off its seat until its spring pressure is reached? I'm targeting 24psi and at 69.5% it's probably lifting off the seat well before 20psi. If I could improve the transient response of the Full, I'd be very happy with it. The lag time to hit 0psi is very fast, but time taken to recover to full boost between shifts is too long IMO.

This is logged transients to ~24-25psi 1st to 3rd. 2nd is ~0.9sec to 25psi, 3rd is ~0.7sec to 24.5psi. This was using a non 3" catback though which was choking it, I expect this to be a little better now. I could probably make 2nd recover/spool faster with WGDC increases as currently I have mirrored 3rd gear into 1st/2nd columns but load of course strongly effects recovery. Thoughts?

 

Unless you have Popeye forearms, if you can easily fully extend it one-handed while its on the car then it is lifting early and killing spool and slowing transients. The stock WGA spring is in the 8-10# range I think.

The diaphragm not seeing manifold boost pressure until over 3500 RPM as you describe does not mean that the flapper is not lifting way earlier than you imagine it to be though. Contrary to your theoretical take, I would guess that your flapper as set up, is cracking off the seat and lifting measurably by about 7# in real life.

Mod is as follows: 1) Remove actuator from turbo. 2) Clamp actuator rod in bench vise. 3) Remove turnbuckle and back up nut from threaded tip of actuator rod. 4) Cut 3-4 threads from tip of actuator rod with hacksaw. 5) Discard backup nut. 6) Tighten turnbuckle all the way down(w/o nut) to where tip of rod bottoms out inside turnbuckle. 8) Reinstall WGA.

Incidentally, did you previously mention that you are running a crushed metal MR DV?

 

Haha, no popeye forearms here. If it's not slippery, I can hold and fully extend while on the car yes. Thank's for the how-to, don't know why I never thought of that. I like the idea of the lock nut staying to hold the turnbuckle vertical on the flapper rod though, so I think the most I'd be comfortable with would be bottoming out the turnbuckle against the nut. I can always just get a 18psi turbosmart actuator too.

I'd forgotten about the pressure of the exhaust being able to lift the flapper off the seat Maybe there is merit in trying this before I go pulling the turbo and spending big $.

No crushed DV, I'm running a synapse DV (I listed the mods you asked for a few posts back, must have missed it).

 

The backup nut is unnecesary because you will be running the turnbuckle spun down all the way clockwise to where the rod bottoms out inside the turnbuckle. I want you to bottom it out. If the flat is not vertical then just back it off a hair. The backup nut will not be needed as a place marking device in this case. In fact, it will get in the way of the desired specific turnbuckle location and desired overall actuator rod length.please.

Just try it my way and then you can always replace the nut later after we are done if it does not impede us from shortening the throw enough. I dont want to have to get mad and fly down there LOL.

Seriously, the stock actuator rod length and turnbuckle assembly only allow a couple threads of adjustment and I dont want the backup nut interfering because it will take up a couple threads of turnbuckle travel. I did one of these on Saturday and the backup nut interfered, although that was on an VIII turbo. But, I think they are about the same.

 

Guys I have been reading forever on here and I am stuck. Can you tell me how this turbo would perform ATP Turbo GTX3071R Stock Location Bolt On Turbo vs the others?

 

Everything I've heard from people who have run the ATP housings has been negative. For a 400-550 whp range its hard to argue with the available stock frame options.

 

I too have only ever heard and read negative things about ATP's products. If theres one thing I've learned from others its if you're gonna go with a upgraded stock housing turbo for the Evo 8/9 go with MAP, CBRD, or Forced Performance.

 

@E_Kobz. Great thread . I, like many others are in the same boat...err, car as yourself. I'm looking for a stock frame turbo on the stock block. I've done all the simple bolt-on mods along with some others (cams/heads,etc).

I was wondering if you decided on a route to take? I've been in talks with Chad himself and paving a path now.

~Chugs