Jim Galbally

was thinking about safety features for my turbo install lastnight and came up with a few ideas on making it less likely to melt...

the main features im thinking of are overboost protection, and protection against high ACTs breaking things...

with the overboost i was thinking just a screw in type boost switch set to kick in at a boost level thats unsafe (eg if its ok upto 9psi then have the switch kick in at 10psi) and then have this switch cut the ignition like a hard cut revlimiter

with the ACT side of things... the car WILL NOT retard the timing if the ACTs get too high (like a cossie n rst does) so if the do reach a critical point (60degs IIRC?) i need something to happen... i was thinking maybe flick the amal valve into low boost mode? (the amal valve will be wired into a switch on the dash) its not the ideal solution but its better than nothing (imho) ofcourse i was thinking of using a mikeR act gauge to give the signal for this to happen (this is where you come in mike) so i need to check that that gauge can be modified to give out either a +12v or to cut a +12v when temp reaches xxx degrees (also is this figure user configurable?) also i'd like this feature overrideable so if i WANTED to i could run full boost at 999degrees... lol

what i need help with really is the wiring... this side of things i assume will need a series of relays to make it all work properly... but im not too good with electronics so would need some input. basically i need the following strategy translated into a wiring diagram of relays:

variables...
SWITCH 1 = LOW BOOST (amal 0)
SWITCH 2 = HIGH BOOST (amal 1)
SWITCH 3 = HIGH+OVERRIDE (amal 1)
AMAL 0 = LOW BOOST (off)
AMAL 1 = HI BOOST (on)
ACT 0 = NORMAL TEMP
ACT 1 = TOO HOT TEMP

IF SWITCH = 1 THEN AMAL = 0 (and ignore ACT)
IF SWITCH = 3 THEN AMAL = 1 (and ignore ACT)
IF SWITCH = 2 AND ACT = 0 THEN AMAL = 1
IF SWITCH = 2 AND ACT = 1 THEN AMAL = 0

(please excuse the techy geek programing looking way of writing )

also one mre thing... with the overboost, how do you cut the ignition... do you short out the -ve and +ve side of the coil together? or do you earth the +ve side? or well... whatever... lol

cheers

also any other ideas for how to make the car SAFER would be greatly received

Stu @ M Developments

iTrader: (12)

These have been for sale for over 10years. I have 20 on the shelf


I will ponder the rest of your idea later...

Jim Galbally

good good stu that means that i wont bother buying anything before venturing to sunny blackpool then

Mike Rainbird

iTrader: (3)

Jim,
Yep our ACT gauges can do that at a user defined temperature point (just needs a relay), but why don't you use this to fire up a home made water injection set up, so that it stops the temperature from climbing?

I.E. You could wire it up with a boost pressure switch so that if it sees boost in excess of 7psi (so that it doesn't pump water in the engine due to heat soak) AND the ACT is above 42°C, the WI fires up to hold the ACTs well below your threshold.....

Jim Galbally

i agree that that is a very good idea mike...

but for the time being i'd rather keep it simple and just lose power/boost when things get too hot, rather than trying to retain the power/boost and supliment the colling system...

also mike does the signal give a +12v output when temp reached, or does it provide a constant +12v output, and make this 0v when temp is reached (switched live or switched earth)

also got me thinking tho...

stu, do these boost switches have 2 stge on em? so say i could use mikes idea to make summink happen at 7psi and still keep the 10psi cut (rather than running 2 seperate switches)

foreigneRS

as i understand the ACT side of things on a cossie, there is a map that retards the ignition when the ACT goes higher. when it reaches a certain temperature and no more retard is applied, then it activates the amal valve to run at low boost.

i quote form the yb engine service manual, online in the Tech Essays Archive:

MWF

Jim is this a 2.8 turbo kit you are installing?

If so there is a standard overboost protection swtich which was orginally sold with the kits. This switch is fitted to the underside of the plenum and goes to the coil to cut the spark if the boost surges over about 12psi I beleive. Sadly I cannot find any info on the wiring as people either keep the info to themselves or simply don't fit the overboost cut.

Regarding you ACT's are you aware Micro Dynamics make adjustable timing boxes which can be boost driven aswell? The EMS5 and EMS6 I beleive, they have dials on the front allowing you to advance and retard the ignition and have a MAP sensor which will adjust the timing automatically, I beleive some people have tried fitting these to the 2.8's with varied results.

What kind of boost are you planning to run? Remember on standard compression I was running 9psi with no ill effects, I didn't even adjust the fueling (silly) and never suffered pinking to my knowledge. Remember the 2.9's rely on their low rpm torque so engine temps aren't that high.

Jim Galbally

chris im planning to run a low boost setup so <10psi

im aware of the EMS stuff but i dont beleife it will be necessary with the low power i intend to run as ill be using a modded dizzy anyway.

as for the overboost, i thought that it was aftermarket only... seen it ona few 2.8s

MWF

As far as I am aware Jim it was standard fitment on dealer fitted kits, but I guess a lot of the DIY jobbies would have excluded it as it's a tad more tricky to install.

Below 10psi you are laughing, with the proper sized intercooler on, decent radiator and electric fans I don't see your ACT's being a problem providing it is setup right.

The compression is only something like 7.2:1 on the standard engine so at 6psi it's runniing at about 13:1 with plenty of retard. An RS-turbo is 8.3:1 and at 12psi youd be getting an effective 14:1 compression ratio. I aren't sure at what stage the ACT's start becomming critical but it might not be too big an issue as you think.

Stavros

Jim, go down the scrapyard and find a renault5turbo, they have the exact overboost sensor you need, as its fitted to them as standard!

Standard setting is 15psi, but as GTTs are so the overboost switch has a screw so is completley adjustable.

Its on the pipe between the turbo and intercooler, quite big, cant miss it (but small enough to slyly fit it in your pocket and walk out the scrappy without paying

Its the OPPOSITE of how water injection boost switches work if i remember correctly-
Wheras WI boost switches turn ON when its hits the desired boost level, the GTT overboost switch turns OFF when it hits the deired boost level.

Actually, after i go do the lottery il go look in "Steves GT Turbo Breakers" (ie my shed ) and if i still got one (used to have loads) il post it you for owt mate

MWF

Yeah on the Turbo Technics jobbies the overboost cut usually goes in line to the coil so cuts the feed as it gets triggered.

Might go find me an R5 overboost switch!

Thrush

iTrader: (1)

Jim Galbally

nice one guys thats the easy bit out of the way then

also chris, i think the std compression is closer to 9:1 (i know the 2.9 is 9.5:1)

Doh

standard c/r is 9.2:1

Jim, re the ACTS i would just fit one of mikes guages and motor it. your making assumptions without any data. for al you or i know is the acts will never get above 40 degrees surely the easiest soluton would be wire mikes guage in to a nice big LED on the dash and if it come on whilst your on the track SLOW DOWN

Rene

sorry to bump in but what ACT on a cossie is acceptable (need to set me alarm for my SECS)

Jim Galbally

doh i intend to do that mate (ie monitor ACTs n see what theyre like

the cooler im using is the RS500 style one (ie big front mount one that obscures the entire rad) so with the boost i intend to run i dont expect to ever see ACTs above -20deg C

but im thinkin about "just incase" what if i dont notice the ACTs getting too high, or what if i do notice n think "fuck it, if i keep it floored for longer i can get 0.02 quicker on the 1/4m"

MWF

Then you'll blow up a Ł50 engine Jim

Stavros

Couldnt find one last night but im SURE i have one (had about 20 once, lol) so il have another look a bit later!

BTW if you DO need to go get one, early ones are bigger than later ones, but they exactly the same, so dont worry if you see ones 2 different sizes.

Jim Galbally

cheers

Doh

i doubt you'd every see acts that high at the pod, i dunno what acts mine runs(i've got the big cooler too) but i do know the engine itself runs too cool due to the cossie bits on the front.

track days i'm sure would be a different story

so when you getting this kit fitted anyway?

Jim Galbally

soon