Alpine R8 GT Turbo Too?

[BobG]

Got the new starter installed and it runs much faster than the 60 year old R8 unit. Plus it's a Lecar (R5) starter so more R5 karma.

Did an oil flow test. Cranked the motor with starter with the oil return line to the sump disconnected. Very little oil flow and no oil from the sump (good). Then disconnected the feed line to the turbo and got lots of flow. So I think the turbo is getting adequate oil.

So should I see more oil from the drain with the turbo not spinning?

I hope to do more road testing soon after winter subsides.

 

[kevinr5gtt]

having a similar issue when running on axle stands have vacuum pressure showing at -30 psi on the after market pressure gauge goes up to -10 briefly when reved (but doest hold at any pressure) to 3500rpm but do not see any positive boost did you see any boost on your runs under load i am still a few weeks away form drive testing yet. may be unrelated but with engine running the brake peddle goes to the floor and has to be pumped a few times to get any feeling (to much vacuum or just need to re blead )

 

[BobG]

I did a couple of acceleration runs (foot to the floor) from a rolling start to about 4000 rpm on flat ground. The MAP sensor reading increased from about 50Kpa to 100. So the reading went from idle vacuum to atmospheric. No boost (I think). I've been waiting the last 2 weeks for the weather to improve so I can do some uphill runs.

Your brake problem sounds like you need to rebleed.

 

[kevinr5gtt]

I did a couple of acceleration runs (foot to the floor) from a rolling start to about 4000 rpm on flat ground. The MAP sensor reading increased from about 50Kpa to 100. So the reading went from idle vacuum to atmospheric. No boost (I think). I've been waiting the last 2 weeks for the weather to improve so I can do some uphill runs.

Your brake problem sounds like you need to rebleed.

thank i have re blead them this morning seams a lot better you never know with these old cars sometimes weird things can be related hope when its gets nicer you can get some runs in will be interesting to see how it goes

 

[DaveL485]

I did a couple of acceleration runs (foot to the floor) from a rolling start to about 4000 rpm on flat ground. The MAP sensor reading increased from about 50Kpa to 100. So the reading went from idle vacuum to atmospheric. No boost (I think). I've been waiting the last 2 weeks for the weather to improve so I can do some uphill runs.

Your brake problem sounds like you need to rebleed.

Can you measure pressure above and below the throttle body?

 

[BobG]

I can hook up a mechanical pressure/vacuum gauge above the throttle body with a long tube to the dash for viewing. This should measure boost without manifold vacuum, right? Thanks for the suggestion @DaveL485.

 

[Brigsy]

Can you measure pressure above and below the throttle body?

Be better off measuring pressure at the turbo compressor housing and post intercooler/carb top or inlet.

 

[DaveL485]

I can hook up a mechanical pressure/vacuum gauge above the throttle body with a long tube to the dash for viewing. This should measure boost without manifold vacuum, right? Thanks for the suggestion @DaveL485.

It'll do for now, you should see positive pressure only before the throttle body, vacuum and pressure after.

I suspect you wont see any pressure above the throttle body though, from what you are saying. Doesnt sound like you have any boost at all.

 

[BobG]

The pressure at the compressor outlet will tell if there is any boost from the turbine. I'll do some pressure measurements after the Ohio winter subsides.

 

[Brigsy]

Also check you are getting full throttle. Need throttle wide open on the 32dis for stuff to happen.

 

[BobG]

I checked for full throttle when I was setting up the linkage. I need to recheck.

Better weather coming so I can do more road testing!

 

[BobG]

Had some good weather today, so I tried a couple of things. Drained the 10W-50 racing oil and replaced it with 10W-30 synthetic. I was concerned the high oil pressure (80 psi cold at idle at 50F) was causing a small oil leak at the bottom of the turbo cartridge. Oli pressure went down to 60 or so but still seems high to me. Still had the leak with the lighter weight oil.

Why is my oil pressure so high? The motor has the original bearings from 1985, but it has a GTT oil pump. I'm worried the high oil pressure will dampage the turbo. Also, will the high pressure tend to drag on the turbo shaft and not let it spin freely? There is plenty of oil flow to the turbo but much less from the drain. Could the journal bearings be too tight?

I also connected the MAP sensor to the compressor housing. The needle barely moved above atmosphere when I revved to 5000.

I'd like to situation cleared up before I start acceleration runs to avoid turbo meltdown!

 

[ren5gord]

You will now see any positive pressure by just reving the engine. It requires load on the engine to start make pressure.

60psi cold is ok it should drop to about 15-20psi when hot at idle ~1000rpm Oil temp ~85c

 

[ren5gord]

When u raise the revs does it go about 60psi? Could be a stuck pressure relief valve in the oil pump.

 

[BobG]

You will now see any positive pressure by just reving the engine. It requires load on the engine to start make pressure.

60psi cold is ok it should drop to about 15-20psi when hot at idle ~1000rpm Oil temp ~85c

Oil pressure at idle with water temp at 180F is still above 50 psi.

When u raise the revs does it go about 60psi? Could be a stuck pressure relief valve in the oil pump.

Not sure if pressure rises above 60 with revs. I'll check it tomorrow. I rebuilt a used pump with new moving parts. I had the relief valve apart and it wasn't stuck then.

 

[Steve Swan]

Would have to think the Turbo is suspect, That journal bearing will flow quite a bit of oil (esp when hot)

 

[Big Steve - Raider]

Would have to think the Turbo is suspect, That journal bearing will flow quite a bit of oil (esp when hot)

He just had it all rebuilt tho?

 

[Brigsy]

Oil pressure is fine even 80psi cold. Will drop when hot prob around 55-60 psi hot 3k + rpm.

Your oil pressure will be higher than c1j as no oil fed timing chain tensioner and oil cooler, wont cause any turbo issues. Turbo core leaking oil suggests poor tolerances when rebuilt if oil return is Ok.

Id personally be running 10/40w or 20/50w.

 

[BobG]

Would have to think the Turbo is suspect, That journal bearing will flow quite a bit of oil (esp when hot)

He just had it all rebuilt tho?

I've started to suspect the turbo myself. I started with a used original T2. The turbine housing was cracked and the shaft, bearings and housing showed considerable wear. So I replaced the turbine housing, turbine wheel and shaft and bearing housing. I bought a rebuild kit and replaced the bearings and seals myself. The shaft turned easily in the housing with no noticable axial or radial play. I then had the unit professionally balanced.

Here's a schematic of the turbo parts.

Parts 3 and 4 weren't in the kit I used. Could they be the reason for the oil leak?


I removed the turbo from the car yesterday. It still spins freely with no shaft play. The oil leak is from the turbine end of the shaft. The "piston ring" seal, part 5, is new.

I also checked the drain line. The outlet on the turbo has 13mm ID and my hose and fittings are all 12mm ID. There is a slight droop in the line which I will correct.

I'd like to think the oil leak and possible lack of turbo spinup are separate issues.

 

[Brigsy]

Probably needs a larger seal on the exhaust side, i guess tolerances are a bit out.