5 GT Turbo EFI - GT Turbo

[Ash4ord]

Hats off to you mate, This build and thread is legendary, All of the information and experiences you have documented on here is priceless.

 

[Mark Davis]

Yes, but I won't so I wanna know the answer lol

I'll ask mate

 

[Mark Davis]

Hats off to you mate, This build and thread is legendary, All of the information and experiences you have documented on here is priceless.

Thanks mate, it's getting a bit convoluted now but will hopefully help some people out in the future.

 

[Mark Davis]

Haven't posted for a while, not a great deal going on but I have got a boost leak that I cannot track down. So I have bought a boost leak tester which I need to collect from the post office tomorrow, I'm losing about 4/5 psi from somewhere and its noticeable power wise.

Tomorrow I pick up a freshly built gearbox courtesy of Mark Galvin, will store it until I can get the funds together for a Quaife. (probably Oct/Nov once new house is sorted)

Also picking up a louvred bonnet and a couple of doors this weekend. I'm going to need to get some body work sorted once the summer is out so collecting parts ready for prep/painting.

Now also have all the parts to start plumbing in swirl pot (other than brackets to hold pumps in place)

 

[davemaygtt]

You picking up the parts from Mike or some one else Mark? Good luck tracking the boost leak down! Think I might be suffering the same issue at mo but unfortunately not much time.

 

[Mark Davis]

You picking up the parts from Mike or some one else Mark? Good luck tracking the boost leak down! Think I might be suffering the same issue at mo but unfortunately not much time.

Picking up the doors from Bruce Hockley and the bonnet from a chap in Worcester.

 

[DaveL485]

Now also have all the parts to start plumbing in swirl pot (other than brackets to hold pumps in place)

Check out Alloy Racing Fabrications on eBay, I got mine from there, top banana for the pennies.

Items in Alloy Racing Fabrications shop on eBay.

 

[Mark Davis]

Thanks Dave, will check them out.

 

[James5]

@James5 how long did yours before it all went wrong ?

My genuine garret GT2871r lasted just over 12 months with the 2 step antilag rear bearing cage couldn't take the heat, it's now deactivated and I am running a gen2 gtx 2867r now

 

[Mark Davis]

Check out Alloy Racing Fabrications on eBay, I got mine from there, top banana for the pennies.

Items in Alloy Racing Fabrications shop on eBay.

View attachment 21159

I like those Dave, I've emailed them as my Walbro is 43mm and my Sytec is 50mm, just want to make sure they will fit before buying.

 

[Mark Davis]

Boost issues seems to be my headache at the moment. My Forge actuator diaphragm failed which pissed me off, I'm pretty certain when I bought it a few years ago I specified that I wanted the piston type but somehow ended up with the diaphragm one. To be fair they've given me two free diaphragms but losing a bit of faith with the quality now.

I'm now questioning if my MAC valve is faulty at the same time. The car won't hold boost, at first it was hitting ignition over cut (over boosting) at 34 psi so I unplugged the controller altogether and as expected I was getting a constant gate pressure of 15psi regardless of rpm. (Diaphragm was doing its job this time as when it was split was also over boosting)

Following this I plugged controller back in and reduced duty from 64% to 50%. At this point it was making 20psi, I slowly added duty % back in until I ended up back where I started at 64% (scratching head ) however this time it was peaking at 31psi (not 34psi but worst of all tailing off as low as 24/25 psi at high rpm. A difference of 6/7 psi is woeful.

I'm going to test boost circuit for leaks tomorrow and if needed try Chris Turners MAC valve.

I'm not sure I can report fault free motoring since day 1, I'll be honest I'm starting to lose the will.

On a more positive note I did collect a refurbished gearbox from Mark G the other day.

 

[Adey]

its normal on factory cars to have increasing duty cycle to meet the boost request as revs rise, are your flat value?

 

[Mark Davis]

Exactly what Dave told me earlier. Will look at increasing duty % as rev rise. Very disheartening watching boost threshold just drop and drop. Pretty sure I've never seen it like that before.

 

[Adey]

if its a new occurrence id be looking elsewhere for the loss of boost though. turbo itself seem fine? no excess play?

 

[Mark Davis]

if its a new occurrence id be looking elsewhere for the loss of boost though. turbo itself seem fine? no excess play?

I've not checked Turbo to be fair, I'd be pissed. It's done 1000 miles at best. Will pressure test boost circuit and go from there.

 

[DaveL485]

Exactly what Dave told me earlier. Will look at increasing duty % as rev rise. Very disheartening watching boost threshold just drop and drop. Pretty sure I've never seen it like that before.

Conversely in my (limited) experience ive only seen two cars with static duty across the range. Amrits and yours. The others ive seen including mine all vary as the revs rise.

 

[Mark Davis]

When Scoff mapped it, it varied. This time it hasn't.

Will sort boost leak test shortly and if all good I'll raise boost per RPM like you suggest.

 

[Andyquadra]

I'll raise boost per RPM like you suggest.

you'll be ok so long as its been mapped for the increased boost at higher rpm

 

[Mark Davis]

Exactly, which is why I am a little bit cautious in taking that route.

Managed to find a few boost leaks this evening and it's improved things in terms of holding boost but still get random boost spikes initiating boost cuts.

Maybe the fisher price actuator as @Brigsy calls it needs replacing. Will try another MAC valve to rule mine out. Scoff replied today and said despite the one issue you had @DaveL485 the MAC valves are very robust and used in Motorsport, he said he'd be surprised if that's my issue.

Had some fun with a Golf R and a M140i in the process this evening, that cheered me up no end especially when the BMW driver gave the wanker sign.

 

[Andyquadra]

Had some fun with a Golf R and a M140i in the process this evening, that cheered me up no end especially when the BMW driver gave the wanker sign.

LOL isn't that just the generic response from all BMW drivers?