Boot Pressure Shooting Up !

[Jimlad]

* the title is supposed to say boost! ... doh ! *

I noticed this yesterday and today a little.

I was doing 100mph in 5th when I decided to floor it. Turbo kicked in.. car acellerating. Then I heard the revs shoot up quite fast. I looked down at the gauge and noticed the boost pressure was 1.1 heading to 1.2 !

1.0 ( 15PSI ) is safe on a rev1, but I don't assume those are, are they ? Noticed it happen in 4th today also.

Thinking of getting a Blitz Boost controller thingy fitted.

any comments?

[Bibbs]

could be "boost creep" ..

[Jimlad]

what's boost creep ?? Is it bad ?

[Bibbs]

.. erm, it's where the boost creeps up .. and yeah it's bad ..

[Jimlad]

why does it creep up ?

I have no boost controlling device on the car. It simply normally hits 15PSI because of the exhaust and downpipe.

So would a boost controller thingy sort that out ??

[Bibbs]

dunno - I know it's a known problem ..

[Jimlad]

Bibbs.. you're usually full of useful information buddy !!

[Bibbs]

sorry fella .. Cause I've not had the problem I've not done any research .. :)

It's usually due to free flowing zorsts etc .. and I know there have been loads of discusions on IMOC about this ..

[Jimlad]

will see what CRD say. They're slapping a bov on it this week, so will see if I can get a blitx boost controller at the same time.

If I set that to 15PSI, then will it actually stay there? Or will it still "creep"

[Jimlad]

from a quick read on the net, it looks like it's because the wastegate can't bleed off enough air. Hence a bigger wastegate is needed.

Does this sound about right ?

"with no exhaust restriction (since I'm completely cat free) the wastegate can't bleed off enough air which = boost creep. "

can you have a bov and external wastegate ?

[Bibbs]

sounds right .. so bigger (external) wastegate? May as well get a bigger turbo at the same time ..

[Jimlad]

god damn !!

I picked the wrong time to get the unichip fitted if extra stuff needs to get done.

Bigger turbo = forgies... + larger fuel injectors ... = car off road =

[Jimlad]

bigger turbo = expensive £££ !!

Good job I decided the other day to keep my car for a while and turn it into a mad power machine then :D

[Sirius]

I would also suggest boost creep, its fairly common.

Basically at higher rpms and speeds the engine is under more load which means you are producing more exhaust gases which in turn increases the boost pressure - if the wastegat cant get rid of these extra gases the only thing that can happen if for the boost to rise.

It is a problem I currently suffer from on my ST205.

I would say that an external wastegate might solve the problem but as far as I am aware to run this you will have to have a new uprated turbo thats not based on a toyota turbo.

I would also say that 15psi is perhaps a little too much for a rev 1 engine.

I would not have thought that a boost controller will help you in this situation as boost controllers are not able to reduce boost they can only increase it over the normal settings. :)

[Jimlad]

mmm... will see what my local jap place recommends.

Also 15PSI is fine on a rev1

[disco]

ive got a apexi avc r fittrd on my turbo, there really good for checking out stats on your motor if you start running more than 1.1bar on a standard turbo it will melt because of heat and you will get a lot of back pressure, if you put a bigger turbo on you could run less boost and you will get more power so you wont need forge pistons, maybe a good head gasket.

avc-r are the way to go you can pick 1 up on eBay for about £200-£300

and you can run less boost when i put the avc-r in dead mode it runs 0.5bar

[ZeroBlade]

can't u just lower the boost by tightning the bleed valve ?

-Z

[Jimlad]

the boost isn't set by a bleed valve or anything like that. It hits 15PSI since I got the exhaust and downpipe put on. So I can't actually change it.

Anyway.. it would still happen would it not ?

I'm gonna phone my local jap place tomorrow morning and see what they suggest. 2weeks time I'll prob end up having a massive turbo slapped on and crazy power figures... lol. But I'll try to resist !

[KiwiMR2]

It's boost creep.

I would also say that 15psi is perhaps a little too much for a rev 1 engine.

I would say the above as well.....ct26 is at it maximum limits here, it has been sweet for you for a while and may continue to be ok for a while longer but shall we start placing bets on how long till it blows ;)

ive got a apexi avc r fittrd on my turbo, there really good for checking out stats on your motor if you start running more than 1.1bar on a standard turbo it will melt because of heat and you will get a lot of back pressure, if you put a bigger turbo on you could run less boost and you will get more power so you wont need forge pistons, maybe a good head gasket.

avc-r are the way to go you can pick 1 up on ebay for about £200-£300

and you can run less boost when i put the avc-r in dead mode it runs 0.5bar

Apexi avcr SHOULD do the job, as would a profec B, or a Blitz dsbc, or any of the decent brand name boost controllers.....to be honest a decent mbc should even do ok at holding it to your choosen setting. Iv'e read a bit about the avcr's not stopping boost creep very well on MR2's but it sounds like disco's is working fine, I can reccomend the profec B as It holds BOTH my setting fine, and a mate of mine with a worked Gen II can confirm the Blitz dsbc also does a great job.

I thought you were getting a new ecu done soon....does it not have some form of boost controller that you can add to it??

Cheers

KiwiMR2

[JappyBeast]

I'm wondering what stretch of 'private' road you managed to hit 100mph on!

I still havent taken my MR2 over a tonne as I'm worried about my tyres blowing out!

[KiwiMR2]

100 mph....so that's about 160 kph, Iv'e managed about 120 mph and suprisingly enough never hit any speed cut....hit it in My Gen II though, not a nice feeling :(

Cheers

KiwiMR2

[Dame]

Is it worth giving the Unichip guys a call? I'm not sure, but wouldn't remapping the ecu cure this problem? I've not heard any complaints from those with Unichips fitted.

[Bibbs]

I'm wondering what stretch of 'private' road you managed to hit 100mph on!

I still havent taken my MR2 over a tonne as I'm worried about my tyres blowing out!

Wimp .. how else do you find out the car red lines in 5th .. up around 160 mph ..

[Jimlad]

Is it worth giving the Unichip guys a call? I'm not sure, but wouldn't remapping the ecu cure this problem? I've not heard any complaints from those with Unichips fitted.

yeah.... possibly see what the unichip folk say. Will also give CRD a call.

As for which road... it's my own personal strip of the M* ... lol . Would say, but some bugger will be sitting waiting on me next time.. :)

I generally stick to about 100mph, just got bored so floored it. That's when I noticed the boost creep.

As for Kiwi.... yeah, I'm getting a Unichip fitted, not an ECU... simply a piggy back device which can get remapped etc, etc.

anyway.... gonna make a few phone calls.

[Jimlad]

ok... unichip folk said they would be able to sort it out.

:D