Turbo Diesel Cabriolet Project (with head porting pics)

[gldgti]

Well we had a good fun day - weather started out freezing cold, spitting rain and winds gusting to 45km/h. It gradually died down and the sky gradually cleared after lunch.

During the familiarisation session, I could tell that there would be hardly any grip with the old road tyres and the weather conditions, and I could feel the back end wanting to step out pretty much any time I was cornering except when I had the right pedal floored. This is probably a lot to do with the old crusty tyres, the crappt hottuning coilovers and the 38psi highway pressures I was running

Regardless, I went out there and attempted to drive it as hard as I could.

Had a little spin on the first lap of the first session after overtaking a beetle on the back straight, that was fun. No dirt for me though, stopped right in the middle of the track (DOH!)

After that, I didnt have any more mishaps as conditions got better and the grip improved (for everyone it seemed).

Steering was great all day, but the lack of grip probably didnt push the components too hard.

Brakes were also just fine - I did manage to heat the up very well indeed, but I never lost stopping power (I could just smell them bigtime!)

As for the engine - well, it ran like an absolute dream all day - except that I blew the boost hose coming off the turbo towards the end of the second session. I didnt realise it was that hose, so I went out in the 3rd thinking I'd fixed it, only to realise I hadnt, drive the whole session anyway with the hole getting worse and worse, turbo screaming and boost dropped to 8psi (not nearly enough!)

Found the problem after that, cut 35mm off the hose so I could reattach it and run again in the 4th session. Got 3 complete hot laps out of it before it blew out again! Knowing I couldnt shorten the hose any further, I ended the day there having completed ~65km worth of laps.

I tried to fix the hose with a bit of duct tape and some epoxy, turned the boost down to 9psi (the lowest I can go with te controller) and we headed home, wifey at the wheel. The hose held out about 20km, after which point I had a brainwave and connected the brake vacuum to the vacuum side of the wastegate, effectively reducing boost to 0psi and we drove it home that way without any issue. I might add that with no boost at all, it performs quite well still, soaring up all of the hume and F3 hills without a worry - making me glad I bothered to do what little port work I did and use the long runner intake manifold.

Anyway that was our day. It was fantastic fun and I learned a LOT. Should be able to go out there next time and give an even better account of myself and the car, hopefully.

For comparisons sake, I started the day doing high 1:35's and my best in the 4th session was a low 1:27.... I think sorting the rear grip would see a few more seconds off that easily - and If I could drive without looking at the guages all the time probably even more

[gldgti]

Well, after the SS, I've replaced the one remaining rubber hose with silicon, and added some Mad Max style boost control!

The Boost control is the best mod yet as far as I'm concerned. What I've done is to tee off the brake vacuum for some vaccuum supply, and run it to a solenoid valve (available from Jaycar). This supplies vacuum to the backside of the wastegate actuator when open - BUT - you need to bleed air back in when you want boost again, so a second solenoid valve is teed into the line between the first valve and atmosphere.
Using a good quality 2 way relay (that has a 81a and 81b terminal) its then easy to switch it using a simple toggle switch. So, I have a switch on the dashboard now: When its switched one way, the vent valve is closed and the vacuum one is open (limits WOT boost to about 4psi). When the switch is flicked, the vent valve opens and the vacuum one closes, and you get full boost (17psi!).

Why? Well, its a small turbo, and cruising along with 12psi on the highway has been making hte fuel economy less than optimal - before this mod, I was getting 5.7-6L/100km. Now, I'm getting 5.2-5.5l/100km, and also, its WAY cool having a boost switch on the dash - particularly when you take someone for a drive.....

"yeah I suppose its pretty good for a diesel"

>>flick<<

"what the HECK does that switch do?"

[ByronRichesMk1]

"yeah I suppose its pretty good for a diesel"

>>flick<<

"what the HECK does that switch do?"

Hahahahahaha, I can only imagine that situation happening

[Water Boy]

Fast switch. I like it...

[gldgti]

Fast switch. I like it...

Well, you pay good money to have one in a brand new car.... why not have one in a mk1?

PS - it has as yet remained unlabelled - perhaps I would complete the awesome just to label it "FAST"?

[Preen59]

Good thinking, 99!

Should be "Faster" switch.

[Greg Roles]

[gldgti]

oh yeah.

Got all the windows tinted yesterday... pics on weekend - its going to get a polish (first time for everything!)


ALSO - new exhaust is "in the pipeline"... pun intended . I have all the flanges, I just have to order in the bends and the tube.

Can anyone say "full mandrel bends, brushed stainless, 2.5" straight through exhaust, no mufflers"?

[ByronRichesMk1]

Can anyone say "full mandrel bends, brushed stainless, 2.5" straight through exhaust, no mufflers"?

Can anyone say, "Hell yeah!"?

[gldgti]

Well, the paint on this car isn't brilliant. Since we got the car, I have resprayed (myslelf) the front and rear bumpers, passenger door and boot lid. As well as that, its got lots of front end stone chips (we do a lot of km, in the country and on the F3 freeway).

That said, I thin she's looking pretty good. Also got 35% tints on Monday, VERY happy with the results of that!

Pics:










Also, all the steel for the exhaust is ordered, should be delivered next week! Woot!