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Trying To Over Come - Over Boosting

noddle
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noddle Rising Star

noddle

Posted
Posted

Hi,

I've been having issues with over boosting when I reach 5K

so I spent half of today trying to fix my issue,

but alas, I didn't fix it, work perfectly up to 5K (7psi), then after that it climbs to 12psi by 5.5K

I'm not sure what I'm going to do, I didn't want to have a external wastegate,

I'll wait till I fit my intercooler and see what that does. (can't afford detonation)

oh, my setup

L24e N/A engine (no modifications at all)

RB30 injector

EDIS

Megasquirt

full 3 inch mandrel exhaust,

Nigel

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harvo Collaborator

harvo

Posted
Posted

How difficult was it to strip/reassemble your turbo?

Thinking about stripping mine (it's not making much boost at all, was running 12psi) thinking the wast gate might be playing up.

any pointers?

ps: sorry, not much help I know. Checked all your vacuum/pressure lines. Actuator spring might have given up?

Cheers Dan

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OUTATIME Community Regular

OUTATIME

Posted
Posted (edited)

taking the housings off is easy, 6 bolts i think. just centre punch mark where the were so they go back to the same rotation. i had same problem with my old cheap ass turbo so i drilled/filed out the waste gate hole. looks like you've already done that?

if ur actuator arm is an adjustable type can wind it out abit so theres less pressure holding the gate shut so when it extends will open the gate up pooftinth more

Edited by OUTATIME
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noddle Rising Star

noddle

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  • Author
Posted
How difficult was it to strip/reassemble your turbo?

Thinking about stripping mine (it's not making much boost at all, was running 12psi) thinking the wast gate might be playing up.

any pointers?

ps: sorry, not much help I know. Checked all your vacuum/pressure lines. Actuator spring might have given up?

Cheers Dan

As "OUTATIME" says, center punch so you can clock it the same when you put it back together, mine was very easy to pull apart. it was more trouble getting it out of the car (240K).

my issue is too much boost. on a N/A engine, I don't want to destroy piston ring lands.

as far as I can tell, the waste gate is open fully. it just doesn't have enough through put.

maybe when I'm running the intercooler, 12psi may not be a issue, will have to wait and see.

Nigel

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BensDR30 Experienced

BensDR30

Posted
Posted

To confirm your suspicion of insufficient flow, you can simply disconnect the actuator from the flap - this will cause the flap to freely open under exhaust pressure (you could also use some wire to hold it open at all times).

Take the car for a drive, and see if the boost still builds up too much.

I have seen such an issue with an old Hitachi turbo on an L26 - we had to fit an external gate to sort it.

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Factory 5 Mentor

Factory 5

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Posted

On my mates ebay monsta turbo the wastegate did not open far enough for the gas to escape, so maybe try mounting the actuator on a different angle to give it more 'throw' in relation to opening the gate.

another idea is to get a custom dump made, with the screamer pipe coming out and rejoinging the exhaust after the firewall. this will help scavange gas out the gate too

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noddle Rising Star

noddle

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On my mates ebay monsta turbo the wastegate did not open far enough for the gas to escape, so maybe try mounting the actuator on a different angle to give it more 'throw' in relation to opening the gate.

another idea is to get a custom dump made, with the screamer pipe coming out and rejoinging the exhaust after the firewall. this will help scavange gas out the gate too

my original testing before I opened the waste gate hole a little was,

I left the waste gate open (unconnected from the flapper arm),

PSI started to build a 4k, at 5k it hit 10psi, I lifted my foot when it hit 12psi,

I haven't disconnected the actuator this time to test, but I'm very sure it opens to the max, but I will test to make sure.

Nigel

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Boof Mentor

Boof

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sounds to me like your wastegate isnt big enough to flow the amount of gas that it needs, can you enlarge it anymore?? If not might have to go external gate

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Factory 5 Mentor

Factory 5

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Posted

another solution..

read slowly

My T3/T4 has had the wategate 'hole' tapped/threaded, with a big metal 'plug' screwed in it (flush with both sides), then a new wastegate hole drilled in the rear that is bigger and to the side and down a bit. this was to clear the edge of the housing

a different gate installed to cover the hole was fitted too....

kinda getto spec, but its what was done, on the cheap too!

cheaper than external gate anyways

i'll get some pics later

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  • 3 weeks later...
noddle Rising Star

noddle

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hey nigel any progress or updates????

Not really,

I've fitted my intercooler, but I need to hack my BOV, it's off a R32/33, I think it's opening by itself at about 7ish, so I'm going to do this mod http://www.thedodgegarage.com/turbo_bov_mod.html

I think I'm going to leave the wastegate as it is, so up to about 5K it'll run about 7-10 PSI, and over that it can over boost to about 12-15, I'm running rich and pulling spark at about 5K

Nigel

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noddle Rising Star

noddle

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Posted (edited)

I did some data logging this mornining, IAT (intake air temp) maxed out at 30.7C with the intercooler, instead of the 60Cish it would be when doing a 1st, 2nd, 3rd flat out run, without the intercooler

I'm happy with it now, engine revs more freely now (I hit 6.55k RPM on my run today) compared to when it was N/A, it seemed to take a lot to get to 5.5K.

Now I need to get some wider wheels to help stop wheel spin.

and I modded my BOV, it appears to make difference.

Nigel

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Edited by noddle
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