pob on the job

Recently fitted a twin dump Mongoose downpipe, mated to and HKS super drager. Now experiencing huge amounts of overboost in 4th and 5th gears. Connected the turbo outlet nipple directly to the actuator, bypassing the boost solenoid, and blanking off the line to boost solenoid. Still no different. Checked wastegate actoator movement by hand which appears ok. Jammed wastegate wide open, still no different. Everything points to the downpipe choking the wategate gas flow. Anyone else had a similar experience? Turbo is a VF29 by the way. Thinking about refitting the catted downpipe back on

UkLegacyT

hi mate,

i fitted a mongoose twin dump d/p to mine, was the complete 3" system. car only had an induction kit then, and i had exactly the same problem, only mine was hitting the fuel cut in every gear.

think its down to the lack of restriction directly rear of the turbo, and it just spins up so quick that it overboosts

i have since ditched the fuel cut, but note that its not a good idea to do so.
are you hitting the fuel cut??

cheers
ian

ssubaru

Hi had same problem but here is how i fixed it ,first take actuater rod of turbo wastegate then move wastegate to fully open position then turn actuater rod out until it just about goes back over about quarter of the hole, fit rod back on you should find boost about 10psi you then need to use a bleed valve to take boost up from there ,because the problem as you may have now figured out is the rod is to short to allow full waste gate movement after decatting you can solve the problem by doing the above lenthening the rod or buying a uprated actuater with a higher spring pressure
ssubaru

pob on the job

Cheers guys,
ssubaru, how did this affect overall boost control ie, in lower gears? Whereabouts in Scotland are you? The actuator rod appears to be riveted on to the wategate linkage. Is this the case? Did you get an uprared actuator or extend OE rod? If you got an uprated actuator, where did you get it from?

Alan

john banks

Turbo dynamics do new actuators. Not sure about the rods.

Pete Croney

Pob if you jammed the wastegate right open, it sounds like the wastegate gas flow is being severely restricted.

Normally if you jammed it open it would never build any decent boost.

Definitely doesn't sound right.

pob on the job

Thanks John...

Pete,

When I quoted "jammed the wategate fully open" I should have clarified. It was open as far as the standard wategate actuator rod travel would allow. Even so, as you point out, wategate gas flow appears to be severely impared and indeed something is not right. Not only that, others appear to have come across the same problem. I'm not so sure I like the idea of doing more mods to get around a system that looks good, but clearly isn't right.

Which downpipe design would you suggest Pete? plug plug

ssubaru

HI my waste gate rod is threaded but uprated actuater best, the problem pete is talking about is right because the flow is restricted because the rod is not long enough to allow full wastegate opening this is ok for standard cars but once you decat you are now flowing alot more air at high revs and you only notice it in 4 and 5th as these gears are held longer so allowing a lot more air flow and boost starts to get higher due to wastegate not dumping enough boost so wastegate cant cope as it is not opening fully,so either buy a threaded actuater or a uprated one , once i found out how to fix mine the boost stays same in all gears
ssubaru
ps only fixed this fault after going to many tuners who couldnt find what was wrong eventually one figuered it out, which was my self ,all i did was take of rod ,then hold wastegate fully open then i tried to refit rod ,i then found out rod was to short to reach so thus needing extended to allow full wastegate boost dumping ,i have come accross this on another car so trust me and give it a try

pob on the job

No probs Ssubaru, I was in no doubt that it would work, only that it's a bit poor that alterations/ further upgrades need to be done with this type of downpipe. I haven't heard of there being trouble with the open neck designs. This certainly wasn't pointed out to me at the time of purchase. I'm not sure if my supplier deals directly with Mongoose, but either way, was totally unaware of any possible problems.
I'll give the rod thing a try when I get home again....in two weeks....bah! I'll drop you a mail or post something up to let you know how I got on.

Thanks again,

Al