[Mk2] [Turbo] boost control and boost spikes.

[Ryan S]

ok, just looking for some infor on how people control boost etc....

I have a nice wee EBC which i'm fairly happy with, it does an ok job but when you come on boost hard, it does go over the target boost slightly, I run the car at a 14psi, if i accelerate hard, it'll boost up to maybe 16psi sometimes 16.5psi then it drops back down again, i want to run the car at 17psi but i'm terrified the spiking will ruin my engine, so i run it at a poxy 14psi just incase, the way round this is to turn up my target boost and lower the gain but then the boost doesn't come on as strong as i'd like, for instance, i have the low boost mode set to 0% gain, so the car boost to around 5psi slowly climbing to around 10psi, so no chance of spiking, the boost does come on unbelievably slow though

another thing i thought was that when i had my MBC, i only had a normal stepper gauge, which i still do, this doesn't show the boost spikes as they happen so fast, the gauge on my controller is very fast and very accurate (it measures in 0.0, so 13.2psi 14.7psi and so on) so now i can see if it spikes. i'm fairly sure that with an external wastegate i'd probably not get any spiking as the controller does do a pretty good job despite only being single solenoid.

anyway, what do you guys do?? is spiking for a couple of 100ths of a second safe??

[Marf]

My view was always if its under fuel cut, it's probably ok. That said I tended to keep boost around the 17psi level and it took some faffing to get the settings right.

Also bear in mind outside temp affects boost levels.

Set it up now in 7degC weather and you'll boost more in colder weather and less in warmer weather.

[Ryan S]

double post.

[Ryan S]

Hmmm, my problem is I have a blitz ecu which I think does away with the fuel cut, it's apparently mapped for 22psi so even if it did have fuel cut, it would be nowhere near where I wanted the fuel cut to be


grrrr, first double post in 9 years!!! what is fuel cut on a rev3??

[Ryan S]

anyone else got anymore info??

i've seen a flange that i may be able to use (iwas gonna do this with my rev2) to make a divorced downpipe, that way i could use an external wastegate with my CT20 (i'm perfectly happy with the performance of the CT20)

[Marf]

Which EBC do you have?

Any good EBC will have a max setting beyond which it limits boost. My Blitz SBC-IDIII allowed you to set a max and also a % amount to reduce boost should you exceed the max. Start there.

Now set gain to 0. Now start with your boost setting. Set it to the desired value and then adjust gain until you achieve your max boost.

You will want to test in all gears and adjust the settings until you don't get the boost limit kicking in. You will be trading off spool rate against creep/overboost.

I set my max boost as 17.5psi and my high boost setting was as close to 17psi as I could make it. This was well under fuel cut and I was happy for the car to be running that boost with my ST205 chargecooler.

If you can't achieve your desired boost settings then one of these things is true

1. You're not setting it up correctly.
2. It's a crap boost controller
3. Your boost controller is broken.

You really want dry weather and minimal traffic to set one of these up yourself

[Ryan S]

hahaha, i reckon it's option number 2 mate

this is my boost controller.

http://rspec.co.uk/boost-controllers/el ... roller-psi


don't get me wrong, it's a good wee controller and i have to admit i've probably not played about with it that much, the only settings it has are desired boost, up to 30psi i think, and gain, so, if i set it to 17psi and turn the gain to 100% it will boost to around 18-19psi then drop back down. it's ,more the spiking that concerns me, what is fuel cut on a rev3?? is it 19psi??

[mrturbotom]

18psi is fuel cut.
But a spike will unlikely make it cut in.

What you're describing can be deemed normal.

My ebc states in the instructions to set the ebc limit to 0.2bar over desired maximum for spike reasons

[Ryan S]

18psi is fuel cut.
But a spike will unlikely make it cut in.

What you're describing can be deemed normal.

My ebc states in the instructions to set the ebc limit to 0.2bar over desired maximum for spike reasons

ah ok, that's put my mind at ease a little then, the problem is there's not really any place to set it up properly, i mean a half decent pull in 5th is well over 100mph

[Marf]

Sure is

[Ryan S]

Sure is

what's the best gear to set it up in 5th?? actually, i guess whatever gear would give the highest boost would be most obvious

[MR2 Rich]

I'm sure Peter told me to set my EBC by accelerating up hill in 4th.

[Ryan S]

Oh, I might give that a go, maximum load on the engine that way I suppose.

[Peter Gidden]

I'm sure Peter told me to set my EBC by accelerating up hill in 4th.

Yep. I use J37M1 exit ramp. 1 mile of straight, constant incline. Long enough to get one 3rd and 4th pull, pull over, adjust, and another 3rd and 4th pull. Then round in a circle back to the previous junction, and repeat.

You'd have to be doing silly speeds to set up in 5th.

I did one this weekend. Blitz DSBC, 16.5psi.

[Ryan S]

Cool, theres a massive hill at a ski resort near me that I can use, any input on boost spikes Peter?

[Peter Gidden]

With a good EBC, and around 16-17psi max on a stovk Rev3 engine, never had a problem.

[hmltnangel]

I had my Profec B setup perfect on the car before breaking. Itd hold 17.8 with no spikes.

Highly recommended EBC

[Ryan S]

Yeah I was trying to ask if some boost spiking was acceptable haha

[jimGTS]

3rd is likely easier and safer than 4th.

revs round quick and less top speed.

setting boost up in 4th or 5th is likely to give you undesirable 1st and 2nd gear boost consistency.

least thats my experience, im always fiddling and dialing different settings for my ebc to try out possible improved settings, you dont need some big long stretch of motorway.

[Ryan S]

the problem in Scotland (at least the area i live) is there's not a lot of straight roads i do know of a couple of quiet ones, i'll have to go there and play around