engine and drivetrain Tuning/Sorting my Turbo

[JackF]

I have recently sold the Turbo, but in putting the package together for the new owner I ran across some of the emails from Ray Korman on the tuning issues on the engine re-build and thought I'd offer them for reference. My kkk was shot when I bought the car and I was led to believe that the Garrett was the unit to go with. Both Ray and I spoke with folks from the US, Neth, Germany and the UK. Based upon information received we ended up sourcing a Garrett kit out of the UK. The shop who put the kit together had never sold one for outside installation. Keep in mind that once the motor was up on the dyno we went back to all the people who recommended the Garrett and asked how they had solved the problems we were seeing. It turns out that none of them had ever dyno'd any of these motors. Anyway, here goes. ( ) are my comments. Also, while reading this keep in mind that max power was not the goal on this motor. The kkk was unobtanium and the Garrett T 03 a simple drop in which would require few other mods. I could for all intents and purposes have a close to correct factory turbo with a Garrett. Simple! My goal and my instructions to Ray were to build a solid, long lived turbo motor. Nothing weird, tricky or peaky. All the internal engine parts are factory spec the only internal mods were to improve oiling so an E36 piston skirt oil spray system was added. Ray's dyno ended up showing 185 hp at 8.5# boost @5800 rpm, Tourque was 194# at 8.5psi at 4600 rpm. Other specs were 89.25mm Bore, 80mm stroke 6.9:1 CR, valve lift, OEM, 25* adv, 93 octane unl. In the attached photo you will see an IC where the battery was. Once I had the car home in MA for the first driving season, there were a few shake down issues and I returned the car to Ray. The engine bay was really tight and I asked him to move the battery to the trunk. Ray, being an enterprising guy, said, "Ya know, Jack, with the battery in the trunk we have room for a nice little IC. Harkening back to Corky Bell, who btw was consulting on this motor, in "Maximum Boost" he says, "a lot of people look at the addition of an intercooler as icing on the cake, where in reality it is really more cake." I agreed that it was a good idea and there it is. The motor was not dyno'd after the IC installation. The car is very fast with virtually no turbo lag. The hot set-up on most 02's is the CR-5 speed. On this car I installed an OD 5 sp. As the car comes onto boost at such low rpm all the CR 5 would do is chop up the power band. The OD 5 is right on it. It also came with an open 3:45 diff which was re-built as a 3:45 LSD by Dave at Aardvark with stronger 3 series internals. Ok, now, here goes.

 

From Ray…We still have not sorted out your turbo kit. It has had a serious impact on my business. It is back up on the dyno for the fourth time. We have only one dyno and once again I now have four other motors overdue out but waiting for us to get the turbo motor out of the way.

 

We sent the k-pump and enrichment device off to be re-checked and richened four times. The German specialist that does our work is a former Kugelfischer employee and he even discussed our problems with a retired Engineer from K-Fisch Germany (who had originally worked on the Turbo project who told him to forget it. It will never work). We were also able to borrow a brand new pump and enrichment device but the same lean results. On the fourth try he enriched the pump well beyond factory settings. It was still to lean but enough improvement that we did not have to immediately back off the power and we could see that the turbo was trying to make 8.5 lb boost with the waste gate full open.

 

The customer didn't mind having extra power  ( ) so to get enough fuel to support the additional boost we welded a boss into the aluminum intake pipe and installed an electronic fuel injector with a computer control (HKS) that allowed us to adjust the fuel according to boost pressure and rpm. The K-F system runs only 28# inlet pressure so we could not just T into the line,we had to add a Bosch fuel pump and another fuel pressure regulator and return line delivering the normal 43# so the electronic injector would work correctly. The cost of all this being over $2000. That done we now had a good mixture but now that everything was running better, the boost went up to 9.5# again with the waste gate wide open.

 

We also observed that at anything over 8 psi the pop off valve was opening partially, actually functioning as an auxiliary waste gate which is unacceptable as it make the turbine spin at exceedingly high rpm. We removed the original pop-off valve and fit a Bosch unit that we have used in other turbo kits. It does not leak at our expected boost levels but it does properly relieve pressure when the throttle is closed abruptly.

 

Now that the pressure leak was closed, the unit made 10.5# boost which was much more than we wanted and would require a good size intercooler. So the turbo unit has been disassembled. We are presently machining the waste gate opening to a larger diameter. If this does not relieve enough pressure, then we must remove and disassemble the unit again and machine out the turbine housing, increasing the distance from the turbine blades to the housing. (This was subsequently done) This will bring the boost up more slowly but is the only way left to bring the max boost level down to a manageable level.

 

I should note that the high boost is not being caused by a free flow, low back pressure exhaust system. We are running our tests with a new BMW original 2002 Turbo exhaust system and we are using the original 2002 Turbo air cleaner assembly.

 

If your previous kits are running well they must have had turbo units machined with a larger diameter turbo outlet or larger waste gate, and I suspect they are all driving around with the pop-off valve relieving the overpressure which will certainly cause short turbine life.

 

That is the edited version of Rays note. In my further conversations with Ray and my experience driving the car I think that as S14's get more and more rare and expensive I think, based upon my car, there will be more M10 Turbo motors built. 

 

In a lifetime of assorted financial calamities the Turbo ranks right near the top…but I had a hell of a good time doing it. It is a GREAT car!

 

[Harv]

Wish you still had it.

So I could drive it.

John

[TobyB]

What were the specifications on the T3?

 

There are at least a dozen permutations of turbine and compressor sizes....  and housings...

...and THAT rabbit hole would probably get you 3/4ths of the way to China!!!

 

t

who agrees, an EFI M10 with a nice mid- sized turbo is a nice power plant.

[JackF]

Toby, I do not know the specs. They would be immaterial anyway as both the waste gate and the turbine housing were machined to bring boost close to factory Turbo spec. I guess they would be on the rating plate on the car, which is still at SCR. I'll contact Matt and see if they can see the information and report back.

John, I thought I offered that when we were at the Vintage. If not, it was an oversight on my part. I would have been happy to let you run it.

[TobyB]

Well, what I'm thinking is that you can adjust a T03 with both compressor AND turbine sizes, THEN the housings have variation in them as well...

 

when I was dinking around with it (quite a long time ago, now) looking at all the pressure maps for different 'trims' was really educational-

each turbine has a certain power output (revs AND torque)  in a certain band, and then the compressor uses that power depending on backpressure,

inlet vacuum, etc, and pretty quickly I started to realize that yes, yes, this really IS rocket science!  

 

And then I went racing, where turbos were not so welcome, and I have yet to really get to where I can spend time figuring out what it all  means ...

 

t

not much help here!

[Harv]

John, I thought I offered that when we were at the Vintage. If not, it was an oversight on my part. I would have been happy to let you run it.

Aw crap! You may have, but every time I'm at the Vintage, I'm on sensory (or BMW geekery) overload! I'm sure it's going to happen to me again in a few weeks.

John

[conkitchen]

Gotta believe anyone who has fiddled with a factory turbo system shares an experience reserved only for those who are really into unique experiences.

 

I'm still chasing ghosts in the machine with my Ah'm (Ray)... tribute car.

[PatAllen]

long time ago when i builded up my turbo i played a lot with the T3 turbine and compressor housings, because i had many of them since i was workin in a SY...renault fuego, Merkur and dodges source to name few.

Sure enough i had programmable efi to play with but at the end i choosen a very small a/r turbine (.36) and a .60 compressor. very low end response and plenty of power even above 6krpm.

i went ffrom a .63, then .48 and ended with the ,36 for better response to the detriment of sub stratospheric high rpm power.

Edited April 17, 2015 by PatAllen

[TobyB]

I was thinking along those lines, Pat- the factory turbo probably had a pretty big turbine, given its response curve and legendary lack of

low- end grunt, and given some of Jack's details, maybe the new turbo is delivering too much boost too soon, in relation to the fuel curve...

 

t

[NickVyse]

Interesting stuff Jack, thanks for posting. The s14 comment is very valid, and yet being lucky enough to have bought an s14 when they were 'relatively' affordable I'd also love a factory-like turbo, but your cost warning echoes everything I fear!

[JackF]

First, I do not have the technical chops to really participate in the numbers. That is Pat's, Toby's, Conkitchen and others realm. I just think that if you drove my Turbo and an S14, many would choose the Turbo. The thing that made my car, in my view, really great was that at around 190 hp, which is stimulating in a 2100# car, the boost was coming in smoothly beginning at around 1500 rpm. I never needed to push to red-line. it was time to shift at 5-5500 rpm. As drivers, that is where we live. Pat, and I am happy you are joining in here, your turbo was in the 285 hp range, if I recall. Mine was amazing at 190, yours...! I guess the thing is with the turbo you can pretty much make it what you want.

 

My car was big money because of the K-fisch and trying to keep it as close to the factory as possible. I can tell you you don't want to get into an R&D with your checkbook and Ray Korman. That is not a slam on Ray whatsoever. He knew enough to find the problems and ultimately to fix them. I enjoyed working with Ray. Turbocharging pretty much requires efi. Take stock motor components with some care in piston choice, efi set-up, a small turbine, intercooler and you have a hell of a ride. I don't know how costs would compare with an S14. I had a chance to drive Tim's M2 at the same Vintage I asked John if he wanted to drive mine, but never got it together. Nick i recall your development of your car. Sounds really sweet!

 

I just think that if someone put it together for a good solid turbo motor the '02 and E30 people would flock to the door. I think there is opportunity there.

[NickVyse]

I just think that if someone put it together for a good solid turbo motor the '02 and E30 people would flock to the door. I think there is opportunity there.

 

I think you're spot on there.