I did infact try the scenario of putting only boost to port C and leaving A+B atmospheric during my previous testing. The valve did in fact act like a wastegate, opening and bleeding off boost rather than the wastegate opening and bleeding off exhaust.

The modulation bucking DID go away, presumably so as the valve wasn't constanyl opening/closing with the pressure differential changes in the manifold. This did however this create other issues with the valve not reacting quite like a DV does and created a noticeable difference in spool times between long shifts. slight compressor surge as well once the valve started closing in between quick boost-to-vac-to boost transitions in the 5-7psi range that did upset the car a tiny bit but note anywere close to what's normally happening. Nothing big, but still not something you want on a track car.

Knowing such I why I opted to build my circuit to isolate ports A+B from vac signals until absolutely necessary. Parts are on the way and I'll have test results very soon.

I cannot at this time go do any testing today as I'm in the middle of a snow storm. You cali/southern state guys don't have that to worry about. I'd go take some video but I truely believe that Eric would not be all too pleased of me drifting his car through some of NY's finest back roads with 3" of snow on the ground

 

BoxerSix,

What I was recommending wasn't leaving A and B to atmosphere with C to boost pre throttle, but to hook A/B up to vac/boost post throttle body (IM). Then adjust the spring tenstion to it's tightest or another spring (assuming that the spring in this DV assists in opening). That should allow the DV to still act very quickly, but not flutter or open during part throttle situations.

 

Gotta admit I love the way Synapse is trying hard to figure this out unlike another Evom vendor I have delt with that would just say you are stupid and hang the phone up.

You know, I am gonna give Synapse a call right now.

D'oh.. only got their voicemail.

 

l2r99gst - I think that Boxersix tried everything. Pretty exhaustive actually. Running too much spring pre-load would actually delay the valve's reaction time. You would get what I call FLUTTERDUMP. Basically, you hear flutter when you let off the throttle, and then about a second later, the big psssh of the DV.

Boxer- when you use the Synchronic as a compressor wastegate, you basically don't have a working DV that reacts to throttle closing.

But what this does tell us is that this is most likely a bonified case of compressor surge line, er surge.

If you get no bucking at 7 psi under part throttle/high rpm, you will at higher boost. So, you are basically back to those 3 solutions I mentioned before. The more I think about it, the more I think that this might be more solveably on the exhaust side. But perhaps at the expense of turbo response. Basically, that existing turbine A/R is small enough to spool that turbo quickly, but rather too small of an A/R for what those cams are flowing. A slightly bigger A/R turbine would probably fix that. It would be interesting to see if a more aggressive wastegating scenario, ie a wastegate that would open earlier, would fix the scenario.

Anybody with an external wastegate out there having this issue?

 

I think you mean Boxersix tested everything, I am following the thread and wondering if I should purchase one of these. Thats why I tried to call.

 

Sorry, we're in and out of the dyno room today. We don't have internet loaded on the dyno computer. Last thing you need is a virus on the dyno

I'm not going to lie, I don't think that a BOV will fix this issue. I really think that a different turbine A/R, or different compressor would fix it. It would be interesting to hear, if anyone out there with cams and a different turbo, is also getting this issue.

Boxersix- are you feeling any other differences with the Synchronic over the stock DV?

 

Syanpse,

I understand the issue that can arise with too much preload. I was merely suggesting it to see if it solves the issue on this particular car. Ideally, you should run as little preload as possible, while still being able to hold the max boost pressure you will run.

BTW, here is the compressor map for the stock turbo for anyone who hasn't seen it before. It's hard to imagine that this can be actual compressor surge to the left of the surge line. Maybe if boxersix gives us the exact RPMs/boost pressures this is happening, we can plot a few points on the map at different VEs, etc to see if it is even close to surging:

 

I agree, compressor surge isnt likely. I never had this problem BEFORE the cams though.

 

how about some boost testing

 

i have one on my 9 with bolt ons and one on my turbo integra i was pm buy members on her and asked how to set them up i just wanted to say both mine work great i will try one of your wastegates next time around

 

l2r99gs- I get what you are saying now. Unfortunately, with a Pull-type design, more boost means the valve seats harder and the harder it is for the 20-24" of vacuum to pull it open quickly. So spring pre-load doesn't help in this design. Running your recommendation with boost/vac to A/B only will only produce late BOV opening and flutterdump (flutter, then BOV opens) as you run more boost. This would probably work with a push-type, like the one you mentioned where boost pressure helps to push the valve open.

 

I appreciate the help Synapse has given here - I'm glad to run their product.

This car did run fine at one point with the cams in. I went back and checked my modification logs and have narrowed it down to one or two changes that occurred after my major upgrades. This car is not a fire breather, and I've seen much higher dyno numbers from guys on the stock turbo, so I'd be surprised if I've surpassed it's capabilities somehow at this level of modification. The changes I've highlighted below don't seem likely as culprits in this, but their timing coincides with the debut of the problem...

March '07: Car has or gets - Buschur oiled intake filter, HKS Racing Suction intake pipe, Forge DV15, AMS LICP, Buschur 10.5 hotside, SSAC O2 housing, Perrin 3" DP, Perrin HiFlo Cat, Borla exhaust.

Car runs fine...

April '07: HKS 272/272 cams, Dynoflash tuned @ 350HP/352TQ on DynoDynamics @ The Shop.

Car runs fine, but get ticketed for loud exhaust on way home from CT by NYS troopers, so...

May '07: Fujitsubo RM-01A exhaust installed.

Car runs at Lime Rock and is fine... and no more coasting by troopers.

June '07: Buschur intake & dry filter installed. Modified Buschur intake pipe by welding breather nipple from HKS pipe onto Buschur pipe for catchcan. Saikou Michi DC3 catchcan (crankcase & PCV) replaces Perrin (crankcase only) catchcan.

Car runs at Watkins Glen and exhibits slight flutter/shudder in the esses, but it is overall great and eats up anything else in my run group... (damned if I can remember experiencing anything on the street before WGI)

June '07: Changed out Forge DV15 spring from blue(?) to red attempting to address bucking. Seems slightly better on the street, but still present.

At some point just before the track events, the car picks up a slight stumble (almost stalls out, then catches) when slightly goosing the gas in parking manuevers, like when backing up in a gas station, etc.

Aug & Sept Watkins Glen events are disasters as bucking is so pronounced in the esses and eventually on other portions of the track that I pull the car from the events to prevent damage to the drivetrain.

After the Aug track event I found several hoses (EGR valve and EGR vacuum solenoid) either off or kinked on the back side of the engine, and reconnect or replace them. No difference.

Sep '07: AMS IC. No difference in the car's issue.

Dec '07: Dyno pulls at Moon Performance - 308HP/314TQ on a Mustang Dyno.

One last clue: the bucking seems to get easier to induce the warmer the engine gets.

 

OK, one last time...it may be me quoting parts of my original post that is confusing things a bit. My original post is back on the last page, post #120. A/B to vacuum/boost, C to boost only (like compressor cover or UICP). Increased spring tension to help alleviate small pressure differentials that may cause flutter.

I think it's a moot point now anyway, as the person mentioned that he is going another route to try to resolve the issue on this particular car.

The Greddy Type-S that I mentioned is a normal pull type BOV, but there is a second nipple accessing a second chamber where a boost only source can be used to help open the DV. I am *assuming* that your Synapse valve is desgined in a similar fashion, with chambers that vacuum assists in opening and chambers where boost assists in opening? That's the only reason I mentioned the Type-S.

Since I have never read your patent or seen your DV, I could be off, but I was assuming that A/B are vacuum open, boost close ports, and C was a boost open port.


Eric

 

Don't overlook the addition of the intake as a non-culprit. I don't run any Buschur parts, so excuse my ignorance, but when you mention intake and filter, I am assuming that you are talking about the intake pipe and cone filter?

If so, the intake pipe *may* be causing maf reading issues, especially if you weren't tuned for that particular combination. Especially since your bucking/stubmling seems to happen around the time that the DV would open/close letting even more airflow into the pipe, possible disturbing the MAF reading even more with that particular intake setup. It seems as though Bushcur has a lot of his parts designed around a mafless system, as evident by the lack of the breather nipple on his intake pipe. Venting the breather nipple on a maf based car can wreak havoc on idle fuel trims and injector tuning.

If you have the stock intake pipe, just for fun, toss it back on and see if it helps with the issue at all. You and your buddy, boxersix, have done so much work already, so it sucks to try even more, but give it a shot.

This also may be the issue with your stalling that you mentioned shortly after that (if not due to the different spring in the DV). This in conjuntion with welding your breather nipple back on the intake pipe will change your fuel trims quite a bit, especially idle, since it looks like you were tuned with it venting to atmosphere originally. This can cause possible idle/stalling issues if not properly tuned.


Eric

 

That, and my name is Eric, too.

Yep.


Unfortunately, I don't. But the HKS pipe had this same setup breather setup, and this issue was not present when it was on the car. Can't put the HKS back on since a) it now is nipple-less, and b) the new dry Buschur cone filter won't fit it like their older oiled filter would, thus the new Buschur intake pipe.


Yep.


The Forge DV15 was replaced by a IX MR valve, and then back to the stock 8 valve (and now a Synchronic! ) - no change in that slight stumble during any of those iterations (but not sure about the Synchronic - the Evo's been kept overnights for observation since it was installed). BoxerSix and a buddy did some datalogging on the car at the December dyno session, and did not see any obvious issues that would explain it. It wasn't vented to atmosphere originally or during the last tune, but it has simply gone from the stock venting setup, to a Perrin catchcan venting setup, to the DC3 venting setup. I do appreciate your thoughts, though.