911SC Turbo

[rfng]

Originally posted by tsuter
If I was buying a new turbo for a 3.0Liter SC DIY install today I would get a TO4E in 54 trim.

turbos and corrected air flow

Thats the hot setup for 930 conversions but they use a 60 wheel.

I think its a little big, especially if you're going to run no more than 9-10 psi. I would used a slightly smaller compressor, with a rear trim of either 63 or 82 for more torque. The problem with the big one is hat it will come in late big flow but no bottom, not a problem if you are going to run big boost. The E is a slightly newer design with a higher efficiency. I think the maps where at 76 efficiency. I would run either a TO4B old design but very good turbo. Try a compressor with either a V compressor or H slightly less efficiency but will build boost quicker, 63 more torque 82 more horsepower and less torque.

[ohecht]

Thanks, rfng. I would think I would feel and use the torque more, although with 9.3 compression, I would expect good performance at the lower end of the range, too. Which of the turbos you mention is best for having the boost kick in lower and smoother? I have heard the stories about older 930s with big turbos and lower compression engines being a handful in the turns if you were not exactly sure when the boost would come on.

Olivier

[ohecht]

Is this a good turbo & deal?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33742&item=2471477812

Olivier

[rfng]

Originally posted by ohecht
Is this a good turbo & deal?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33742&item=2471477812

Olivier

Its a good deal but the a/r is not right for you, unless your going to run 20 psi of boost. With your car you'd be waiting until 4500 for something to happen. this turbo is for top end, or a car which has a lot of exhaust energy ala rotary.

[rfng]

Originally posted by ohecht
Sorry last question, as I read that thread but was confused by the considerations for turbo selection:

What makes the TO4E in 54 trim such a good match, and how does the trim affect things? I read about the "efficiency islands", but I do not fully understand what the axes of the graphs are telling me. I need to understand more about how a selection affects the point when the boost comes on, etc.

Thanks again,

Olivier

Part of it is experience. When you look at the map (compressor) on the left side there are number 1.1, 1.2 etc. on the bottom pound of air it will flow at a certain boost. You have to know how many pounds of air you need based on the size of your engine, how many turns your pipe work requires to reach the turbo outlet to the throttle body and eventually into the engine.

Intercooled requires more pounds of air or volume than a non intercooled engine.

Then you look at the the left side and 1.1 would be 3 psi the first 1.0 is for atmosphere at sea level. So 14.7 or 1 bar would be 2.0 on the map. connect the lines from 2.0 to a straight line going right from 2.0, next pick the pound of air required. Draw a line straight up. Where the line intersects will tell you the the efficiency of the turbo compressor. So if its 72% then as the compressor spins 72% of the work will be making the boost and 28% will be heat (less heat is always better).l

As for rear housings the smaller the a/r the faster the turbo will spin or spool up. The trim is the flow out the back the turbine section and how its cut. N,O, P. P will flow the most in the upper rpm range. N will develope more torque and less raw hp the P and vice versa. Its always a guess, but if you've done it enough you know what the rear housing and trim should be based on the displacment and compression ratio.

[ohecht]

Thanks again, rfng. That is a lot to consider. It is a fascinating subject, though. I also noticed a huge discrepancy in turbo prices. I saw some TO4Bs for $3800+, and then those in the link for less than $400 for the same basic model.

Olivier

[ohecht]

I looked at the space between the end of my SSIs and the bumper, and it is hard to visualize space for a turbo and the pipes that would have to connect both sides of the exhaust to the turbo.

Does anyone have a picture of a turbo installed behind SSIs?

Olivier

[tsuter]

Please keep this thread to BAE installs and modifications to BAE installs for 78-83 SCs.

Use this other thread for SSIs. w pictures

930 3.0L and SSIs

[RickM]

Here's a thread on the 3.2 turbo recomendations. I'm assuming it's similar to a 3.0 application.... Turbo questions.....

[ohecht]

Is having a catastrophic failure of the turbo and having metal bits enter the engine through the oil return line a legitimate concern with these modifications?

I have a read a lot about the advantages of separate oil supplies, etc. for turbos and superchargers, but it seems to be a non-issue for most that have done these conversions.

Is that because turbos are more reliable now? Or is it just highly unlikely that, even with such a failure, metal would not enter the engine through the oil return line?

Thanks,

Olivier

[tsuter]

Separate turbo oil supplies were used for "cleanliness" to preserve turbo bearing life. The engine oil was considered "too dirty" to comingle and use for the turbo. No one could ever "prove" this advantage so you don't see it anymore... although I'm sure someone can find some exception.

[tsuter]

In a catastrophic failure compressor bits are going to enter the throttle body, intake manifolds, valves, cylinders - that is where the really bad damage can occur. Nothing is going to go out the oil return line back to the crankcase.... except oil.

[ohecht]

That does make more sense, I had always only considered the oil route for some reason.

Is that something that would only result from physical damage or severe imbalance, as opposed to bearing failure, etc.?

Olivier

[built4sound]

Hello all,
I hate to rewind this thread a bit, but after a year of looking I found a turbo kit and attempting it's install. My first question is reguarding the modifications to the throttle body connections. On my 74 I don't have most of the components that you guys re-routed. Is there any changes i should make for mine to work?

Thanks,

Brandon

[iamchappy]

Brandon,
PM me with your email and I will send to you a PDF of the BAE installation manual which could be very helpful.

David ( iamchappy )

[iamchappy]

Here are some pictures of my progress, my cross over pipe fabricator was out sick last week so it looks like you will have to wait till next week to hear about the test drive. I installed very similar to sutter the only differences are my use of the power assist port on the lower air box to plumb the Hobbs switch and vacuum pressure gauge, and use of decel port on back of the throttle body for the bov. I used the old pop off valve location for the CSV and boost controller tap. I also tapped the fuel line out of the fuel pump and used an inline filter to feed the CSV. I tapped the MSD btm into one of the ERG ports on the throttle body.

[tsuter]

Looking good! I did learn that the Tial 50mm BOV that we have has three springs: 7, 9, 11 psi. They seem to sell it with the 11psi unless specified differently.
I am going to order the 7psi and see if it will be more responsive at boost of 7-10 psi.
The 11psi spring may be better suited to boost of 15-20psi.

[tsuter]

And here's a new part for Wayne to carry in the online catalog!!!

[iamchappy]

Thad where are you going to purchase the springs from, and where did you get information regarding them. In regards to keeping the bonnet on during higher boost I am going to make up something, a little strap I think is all it would need even a heavy zip tie could work, I am thinking about laying up a fiber or carbon fiber cap for it and use the throttle body fasteners to secure it. More to follow I am getting close to finishing this thing up.

[tsuter]

Tial wastegate springs as well as Tial BOV springs (bottom of page) can be found here.

http://www.lightningmotorsports.com/tialsport.htm