Twin turbo configuration questions: Theory & Application

[tsuter]

I'm still waiting for someone to try two KO3s. They are if anything undersized for a 1.8L (ask me how I know).
And I will donate my removed KO3 to the first true builder who will build a twin 3.0L or 3.2L on the KO3 base.

[ohecht]

Thad,

Can you give me some up close pictures and dimensions of the K03?

I looked into those closely, but shied away after reading so many "ditch the K03 to upgrade to the more powerful & reliable K04" posts on the Audi & VW forums.

Are they oil-cooled?

Olivier

[724doorE]

I'm still waiting for someone to try two KO3s. They are if anything undersized for a 1.8L (ask me how I know).
And I will donate my removed KO3 to the first true builder who will build a twin 3.0L or 3.2L on the KO3 base.


__________________
tsuter
78 911SC Turbo Targa
Thaaaats Right!!

I plan on building a twin 2.2 with 66mm crank and 2.4 E pistons with MFI..... You game????

[tsuter]

Two KO3s are probably going to be a little too big for a 2.2/2.4 liter. I'd check some other possiblities first.

[tsuter]

Here is picture of the KO3 to dimensionalize it. These are for VWs mighty 1.8T but they are a bit small for anything over 200HP in single turbo applications.

[johncj8989]

Would it be plausible to twin turbo a 2.0 (with the good 73.5 7r case) with forged Mahle pistons if the compression is pushing 9.8:1? I know low boost and a cooler would be a must due to the high compression.

Ideas???

Thanks

[beepbeep]

Originally posted by johncj8989
Would it be plausible to twin turbo a 2.0 (with the good 73.5 7r case) with forged Mahle pistons if the compression is pushing 9.8:1? I know low boost and a cooler would be a must due to the high compression.

Ideas???

Thanks

No. 2L is just too small volume to go twin-turbo. Frankly, I find twin turbos on anything less than 3L unnecessary...

[johncj8989]

Even with a single turbo is the high compression viable or is it just too much to consider adding turbo boost?

[beepbeep]

9.8:1 sound a tad too high on two-valve/cylinder aircooled engine. You could probably boost something like 0.3 bar or so, it's probably not worth doing.

There are other cheap tricks that can be den, depending on how your pistons look like. You could turn them few mm's to get lower C/R if they are symetrical.

[KobaltBlau]

Originally posted by beepbeep
9.8:1 sound a tad too high on two-valve/cylinder aircooled engine.

What would you say, Goran? 8.5:1? or higher? Compare to 9.3:1 or so in a saab...

[beepbeep]

As far as I can see, American 1981 SC 3.0 engine had 9.3:1 C/R. Older SC engines that had C/R of 8.5:1 should be much easier to turbocharge.

You cannot compare C/R of SAAB engine to SC engine and expect them to act similar. SAAB engine has four valves per cylinder, cloverleaf combustion chambers, centrally placed spark-plug, bowl-shaped pistons, watercooled heads and state-of art knock-detection circuitry.

SC engine doesn't have any of this, so you have to run low to keep it safe. Remember that early 930 had 6.5:1 and 7.0:1 C/R!

I believe 8.5:1 is good compromise between efficiency, off-boost response and durability when it comes to DIY-turbo conversions on budget using conservative boost. I wouldn't go higher than this. For extra boost, it would be wise with little less compression.

[ohecht]

Thad,

Are the K03s oil cooled? I would appreciate any other pictures you may have of them from the other angles.

Olivier

[KobaltBlau]

yes, yes, and yes.

Originally posted by beepbeep
As far as I can see, American 1981 SC 3.0 engine had 9.3:1 C/R. Older SC engines that had C/R of 8.5:1 should be much easier to turbocharge.

I agree, and you are right on those (quoted) compression ratios. I'm not sure exactly how they come out when people measure them directly.

Originally posted by beepbeep

You cannot compare C/R of SAAB engine to SC engine and expect them to act similar. SAAB engine has four valves per cylinder, cloverleaf combustion chambers, centrally placed spark-plug, bowl-shaped pistons, watercooled heads and state-of art knock-detection circuitry.

I understand these things. What I was trying to say is that there would be a difference, not that 9.3:1 was appropriate for a 911-type engine with the same intended purpose as a saab engine. No offense meant or taken.

Originally posted by beepbeep

SC engine doesn't have any of this, so you have to run low to keep it safe. Remember that early 930 had 6.5:1 and 7.0:1 C/R!

True. I do remember that! Those ratios have always seemed obscenely low to me, but I suppose a lower static C/R is OK with a relatively large displacement light car.

Originally posted by beepbeep

I believe 8.5:1 is good compromise between efficiency, off-boost response and durability when it comes to DIY-turbo conversions on budget using conservative boost. I wouldn't go higher than this. For extra boost, it would be wise with little less compression.

I agree with what you are saying. boost you can run depends on whether you will twin-plug or not. I realized I am rehashing a little from the "small displacement turbos" thread in the ER forum. I will look at that again and reply to your last response.

Thanks!

[ohecht]

Thad,

Do you have any pictures of the K03s oriented like the T-25 picture I have on page 7 of this post with a ruller in the shot? I am having trouble comparing the two sizes due to the different angles.

Thanks,

Olivier

[ohecht]

Also, I have not been able to loosen the giant snap ring on the compressor side of my turbo to clock the housing. I have used every type and size of snap-ring pliers that Sears or anyone else around has, and, even when the pliers fit, the ring does not budge.

Anyone have any suggestions or better tool ideas?

Thanks,

Olivier

[WydRyd]

Curious to know how you guys went with your T25's or K03 TT projects?

Mark, how about your GT28RS's?

How well did they work?

[ohecht]

Mine are still waiting to go in, since I need to switch to EFI and work up the courage to boost a 9.3:1 engine htat is running well. I will probably wait until it needs a rebuild and strengthen it then before adding the turbos. It is a hard project to "get to" on a daily driver...

[ohecht]

Mine are still waiting to go in, since I need to switch to EFI and work up the courage to boost a 9.3:1 engine that is running well. I will probably wait until it needs a rebuild and strengthen it then before adding the turbos. It is a hard project to "get to" on a daily driver...

[Lukesportsman]

Any progress 724doorE?

I live just south of you and would be interesting to bounce ideas off someone more local. I've sourced some 993TT headers already for my project. Have you moved foward yet in ideas or reality? I'm not boosting my 2.7, though.

[RarlyL8]

What are you planning Luke? 993tt exchangers ain't cheap!