911SC (with CIS to EFI) Turbo Conversion

[ohecht]

Is there a way to have Megasquirt control a crank-fired ignition system?

Olivier

[tsuter]

Originally posted by tbitz
Why would a T3 turbine be less reliable than a T4?

On a 3.0 Liter or larger six cylinder motor, the exducer on the T3 turbine is waaaaay too small for the exhaust air flow volume. Premature turbine failure and shaft failure is highly likely.
Even if you go to at least a stage III or the newest stage IV exducer dimension it is still too small. Guys are putting these on 1.8Ts and trimming 10% off the turbine. For the 3.0 you need 2.5 inches or more.

The T3 turbine is matched for the 4 cyclinder sports compact motors. 1.6 liter to maybe 2.3.
For example the T3/T04E hybrid is the most common upgade for the VW1.8T motor. In fact the progression is KO3, KO4, T3/TO4E, GT28. You would never put a single GT28 on a 911. Maybe two KO3s.

The T3/T4 hybrids are all over the compact 4 cylinder market but you won't find one installed on a six cylinder anywhere. If ANYONE says it will run well on a six cylinder I want to see it. Get the evidence and post the link. I could give you a ton of VW1.8Ts and ricers with T3/TO4Es but they are all four bangers.

The best TO4 match for the 911 is the TO4E with a fair choice of the turbine and compressor trims. The TO4 turbine will handle the 3.0 to 3.6 liter.

[ohecht]

tsuter,

Since you mentioned twin K03s, what other twin possibilities do you see for a low-boost twin set up on a 3.0?

I am looking at T25s or MHI's TD04 13 or 15, but I would like to hear your thoughts.

Olivier

[tsuter]

Here is a page from turbonetics on turbine sizing. On their web site is a great deal more technical information but sufficed to say I don't see anyone considerating a T3 turbine for 3.0 liter applications and up. Hence a T3/T4 hybrid is out.



Regarding a twin on a 911SC, I believe there is a thread on that but I have no real expertise in twins other than having an extra KO3 from my 1.8T that I'll give away to see a twin built.

I would say it needs to be sized for a 1.5-1.8 liter and a standard exducer KO3 would be close.

Mechanical CIS or EFI should not make a difference in turbo selection.

[beepbeep]

Originally posted by tsuter

The T3/T4 hybrids are all over the compact 4 cylinder market but you won't find one installed on a six cylinder anywhere. If ANYONE says it will run well on a six cylinder I want to see it.

Well I say that it actually doesn't matter how many cylinders are behind, and that main thing is swept volume. As you try to use some of kinetic energy stored in exhaust pulses, number of cylinders will play certain roll but in completly different way. Of two 3.0L engines where one uses 4 cylinders and another 6, you would actually need to use slightly smaller turbo on six-banger beacuse resulting exhaust pulses would have less kinetic energy thanx to smaller individual cylinder volumes.

T3 housing is somewhat small, but I seriously doubt there is going to be any problems with destroyed shafts as long as boost is kept at reasonable levels and not overspeeding the turbine.

That's why you have wastegate, it will route exhaust gasses around turbo when desired boost is attained.

Bosting 0.5 bar on 3L engine at 5500 RPM (engine is just a air-pump) will move certain amount of air. You can plot that number in compressor-map and see where it is. In this case, boosting 0.5 bar is not worse than boosting 1 bar on 1.5L engine (actually 1 bar on 1.5L might need slightly more turbine revs depending on efficiency-map.

So my message to Tony is:
As long as you don't plan boosting more than 0.5 bar, it's a pretty good choice. There is no danger of "bursting shafts beacuse it's a six-banger and not four banger"- yadda yaddism. You will get quick spoolup but it will run out of puff if you try to squeeze much more.

(But boost is addictive, you know and next thing you know is that you want to run more boost and you find your turbo being too small)

[tsuter]

Hey who says the guys at Garrett know anything anyway about turbine selection. Someones gotta be the first to try things.
Just don't put the oil cooler in the turbo tail too.

[tsuter]

Goran FYI... there are no 3.0 liter motors in the compact sport 4 cylinder market. Unless you know something I don't..... which I doubt.

Or are you talking theory again???

[beepbeep]

Originally posted by tsuter
Goran FYI... there are no 3.0 liter motors in the compact sport 4 cylinder market. Unless you know something I don't..... which I doubt.

Or are you talking theory again???

Porsche 968 is one of rare cars using 3L four-banger (there was even a ultra rare turbo model.)

Unfortunately, such big four-cylinder engines need lot's of attention to solve NHV-issues (balanceshafts etc.) In theory, a four-banger is more efficient than six-banger of same size (less moving-parts friction, better volumetric efficiency etc.) 3L is probably the upper limit.

But yes, we are mostly talking theory.

[tsuter]

The Porsche 968 is NOT in the compact sports market by anyones definition. That market is defined by displacement and price among other things. Honda, Subaru,VW...

I sure hope you're not recommending a hybrid T3/TO4E for a 911 3.0 liter single turbo app.

Because that seems to be exactly what you are doing.

If so, please provide just one link to anyone running this T3/T4 hybrid in a 3.0 liter or larger single turbo application.

[tbitz]

Originally posted by tsuter
.......If so, please provide just one link to anyone running this T3/T4 hybrid in a 3.0 liter or larger single turbo application.

It already been done on a 3.0L 911SC? Richard Fung is using a T4/T3 hybrid in his 911SC turbo kit (which hasn't come to fruition yet).

Check this Pelican link.

[tbitz]

Originally posted by tsuter
Here is a page from turbonetics on turbine sizing. On their web site is a great deal more technical information but sufficed to say I don't see anyone considerating a T3 turbine for 3.0 liter applications and up. Hence a T3/T4 hybrid is out.



Regarding a twin on a 911SC, I believe there is a thread on that but I have no real expertise in twins other than having an extra KO3 from my 1.8T that I'll give away to see a twin built.

I would say it needs to be sized for a 1.5-1.8 liter and a standard exducer KO3 would be close.

Mechanical CIS or EFI should not make a difference in turbo selection.

Ummm..... The 3.0L engine is 183ci which according to the chart you just posted indicates a T3 turbine? So I'm not sure what you are talking about. In fact they recommend up to 200ci (3.3L) for a T3 turbine.

I think a T3 stage III will be plenty good for a 3.0L.

[tsuter]

Richard is a bit contradictory in his explanation at times. He consistently refers (as have you now) to a T4/T3 hybrid which is a T4 turbine and a T3 compressor. That is the opposite of a T3/T4.
People must be precise. The turbine size is ALWAYS stated first.

He also states that his turbocharger is a "custom". Only Richard knows what that is and possibly he will chime in.

The following is a direct paste from Richard's thread. Read carefully. I'm not sure what he means.... but he is clear about the turbine rear oulet as being too small.


"I'd use a t4B/t3 hybrid- either a V compressor, or H. Rear housing I would stick with a .58, stage 1? a slightly enlarged outlet. Although the B design is 20 something years old. it a good turbo, the efficiency of the compressor wheel is about 2% less than that of a E. And for such a low amount of boost it should be fine.

As for the rear housing a stock t/3 turbine outlet is too small, you need a larger one to help on the top end."

Here is a fine picture of TURBINE failure due to overspin and heat. The turbine was undersized for the application. The ONLY good news is that it ISN'T compressor failure!

[tsuter]

Here is a sizing chart also from Turbonetics by displacement. Notice what happens when displacement exceeds 2.4 liters.

http://www.turboneticsinc.com/tsystems.html

Now you may just be planning a 220-240HP build and you may have no plans to exceed 5000 or 5500RPM in your 911.
and in that case you may be fine. maybe....

But others may want the full 300HP+ potential of their car and if so a T3 turbine is a dangerous proposition.

I too frequently see on this board people proposing things like turbo tail oil coolers and other such things and as a technical board there should be support and evidence for these positions.

I have not seen that in the case for a T3 turbine on a 3.0+ liter 911 and peeps need to be made aware of that. And I own and run a VW1.8T tuned to 225HP/245TQ as well as a 300HP+ 911 so I'm actually am not just a theoretician riding a desk on some of this.

Its really no big deal. Install a T3/T4 and put the car on a dyno (if you dare) and see how it works. Then publish the results up here.

[tbitz]

I don't want to get in a great debate here, but...

Your comment about the T3 exducer is "waaaaay to small" is incorrect. If you look at the specs I posted earlier the T3 Stage III turbine has the SAME exducer diameter a T4 "O" trim turbine.

There is also no need to fear overspin. The system is "closed loop" which means rotation speed of the turbine/compressor assembly is controlled by the wastegate. When the pressure reaches a certain value the wastegate keeps it there by controlling bypass gas. Pressure has direct correlation to shaft speed (look at compressor maps). So infact the wastegate controls shaft speed. It doesn't matter if you have T3 or T4 turbine as long as the wastegate is big enough it will control the shaft speed to what you've set it.

Also turbonetics specs there T3/T4 hybrids for 250 to 500hp (link )

Anyhow, I will build it and I'll let folks know how it works out.

Cheers,

[beepbeep]

Originally posted by tbitz
I don't want to get in a great debate here, but...

The system is "closed loop" which means rotation speed of the turbine/compressor assembly is controlled by the wastegate. When the pressure reaches a certain value the wastegate keeps it there by controlling bypass gas. Pressure has direct correlation to shaft speed (look at compressor maps). So infact the wastegate controls shaft speed.

This statement is not completly correct. Wastegate controls boost pressure but boost pressure is not directly proportional to shaft speed.

Turbocharger boosting 0.5 bar into 3L engine will spin faster than when boosting 0.5 bar into 2L engine, despite same boost.

so the bigger the eninge the bigger the turbocharger needs to be to supply same boost.

[1fastredsc]

I think he was proportioning his idea in terms of, t04e with x turbine, or t04e with y turbine, no matter which with the same compressor it still has the same shaft speed in order to produce the same boost in the same engine at the same rpm.
944s2 also has a 3.0.
944t are part of a small community of street racers.
We have a to4e hybrid with a k27#8 turbine on my dad's 951 without any problems (it's a 2.7).
Oh and it's kind of hard to compare with the 1.8t considering it has a 20valve head and variocam.

[Mr Beau]

It should be noted that T3's were used on the first gen 300ZX and the Buick 3.8L engines. T3's top out at a little over 300 HP, so it really depends on what you want power-wise, but you won't be in danger of hurting a T3 at less than 20 psi...

[tsuter]

Yeah, that failed T3 turbine picture I posted was fried on a 1.8T pushing 440HP on a 75 wet shot!!

Nothing wrong with being experimental and being the first at something...but please post up some dyno sheets.... not "it feels really fast to my butt" data.

3.8L Buick turbo six? ... man o man that is old!! get some tech in the last ten years at least???

And I'd still like a link to a "modern day" tuner putting T3/T4 hybrids in anything other that sports compacts that has 3.0L and up.

See I put in "modern day" so you guys won't keep dregging up vintage cars from your boy hood.

[beepbeep]

tsuter:

Claiming things like "you are going to have shaft-failure if you run T3 housing on six-banger" and uspporting those claims by pics of eaten-up turbine from some kid who was messing around with NOx is not what I would call solid evidence

Tony IS NOT going to suffer shaft failure by using T3/T4 hybrid and IT DOESN'T MATTER if it sits on four or six-banger. (it actually doesn but in completly different way than you stated earlier).

His main goal is to boost 7 lbs in 3L engine and I don't see any problem with it...what has dyno sheet and "really fast to my butt" has to do with it?

For example: GT17's are frequently used on 2.3L engines...following your way of thinking, that turbo should't be used on anything bigger than 1.4L engine...

It's a matter of chosing right setup for your needs. If your needs are moderate boost and short spoolup then I believe T3/T4 hybrid is right way to go.

It won't be able to flow 400HP but neither will his C/R support it and he seems to be aware of it. Sometimes, good flat torque curve and short spoolup is better then high & peaky power curve, especially if you are driving on the street.

[tsuter]

Originally posted by beepbeep
tsuter:

Claiming things like "you are going to have shaft-failure if you run T3 housing on six-banger" and uspporting those claims by pics of eaten-up turbine from some kid who was messing around with NOx is not what I would call solid evidence

Goran I already know you can't read and now I know you can't quote me either. So go back and try again.

Please use this thread for turbo selection. You didn't support a T3/T4 in it. And neither did anyone else.... including tbitz.


turbos and corrected air flow