911SC Turbo

[tsuter]

Originally posted by Sebring77
Item #5 has me concerned. I've said time and again, I know jack ***** about this stuff. I'm way ahead of where I was 4 months ago, but still a beginner. Here's the question- What kind of tuning does one do to cis? I thought they were set it and forget it, simple mechanical systems.

Okay-another question-is your wastegate venting into the Fabspeed muffler or straight out?

1. CIS, Cold fuel pressure, warm fuel pressure, CO, Idle Speed, cold start (AAR, AAV, Thermo time switch, CSV).... If you can't make it work right with no turbo, it'll never work right with the turbo.

2. The Fabspeed Stainless Steel 930 dual 4.5" outlet muffler is right side exhaust, left side wastegate. They provide both sides.

[SLO-BOB]

Originally posted by tsuter
1. CIS, Cold fuel pressure, warm fuel pressure, CO, Idle Speed, cold start (AAR, AAV, Thermo time switch, CSV).... If you can't make it work right with no turbo, it'll never work right with the turbo.

Okay. So what if one bolts a turbo onto a cis system that is currently working just fine? Will changes need to be made after adding the turbo typically?

[mb911]

yes you will have to compensate for the additional air into the mix

[sammyg2]

It depends on the boost levels.
CIS measures the mass of the air, not just the volume so it will add more fuel as the turbo adds more air. That happens without any tinkering or modifications.
Now, when the boost levels get high enough to overcome the stock system, or when boost levles get high enough that there is a danger of pinging due to high combustion temperatures, additional fuel is needed to compensate.
That level is normally regarded as 5 to 6 psi. Anything above that will probably require some additional fuel, anything below that is probably just fine in stock configuration.
I ran mine at 6 psi with no modifications to the CIS at all.
When i went to 7 psi I installed a hobbs switch to ground the Lambda brain under boost which fooled it into going richer.
If I were to go higher in boost I would install a 7th injector.
YMMV

[SLO-BOB]

Thanks Gerald,

That's what I thought based on info gathered here-much of it from you. Having the ability to "bolt-on" a system to an otherwise good running cis motor was what attracted me to the bae system in the first place. I'm not much of a tuner either of electrical or fuel systems. My strengths are in mechanical installations such as brakes, suspension componants, transmissions, clutches, turbo hardware, etc.

This is a process for me. I could have just bought a 930, or a blown stang to get a fast car, but as Thad said earlier, this is something unique-different, my own. I'm starting with a simple, low boost, bolt on bae kit I'm hoping to get my car's anemic 160ish hp closer to 250. However, while that's in the car, I'll be researching and building a 3.0/3.3, higher boost, intercooled EFI motor. My goal-350-375 HP. It will be a shallow learning curve, no doubt, but I'll enoy every minute of it!

Thanks again to everyone for the help and advice.

[iamchappy]

BAE KIT just showed up on in the classifieds.

Aftermarket Turbo Kit for early 80's

[SLO-BOB]

Finally made it over to Thad's. Just want to pass along to those on the turbo fence that it is SOOOOOOOOOO worth it! I was blown away by the power Thad's car has. It just pulls like a freight train up to whatever speed you dare go.

It was also cool to get a first hand look at a quality, coherent turbo installation. Top notch.

Thanks Thad for the field trip!

[vinny c]

Just rec'd my turbo parts which resembles the BAE setup but has aluminum bonnets and small intercooler. Will start install with SSI's after smog time in April.
Could somebody email the pdf manual to me at vcmarine@sbcglobal.net. It would be much appreciated.
Thanks

Vince

[sammyg2]

Vince, I have it at home and will send you a copy later tonight unless someone beats me to it.


As I posted in another thread, I just got my new LM-1 wideband O2 sensor/air fuel ratio meter. I plan to have a lot of fun with it.
I also have an idea to hook up an air temperature sender and have the LM-1 record that data to see how hot my intake gets under boost.
Anyone have any ideas or BTDT that might save me from having to re-invent the wheel?

[jcc911]

Vince, Manual sent.

[vinny c]

jcc911

thanks

vince

[tsuter]

Originally posted by vinny c
Just rec'd my turbo parts which resembles the BAE setup but has aluminum bonnets and small intercooler. Will start install with SSI's after smog time in April.
Could somebody email the pdf manual to me at vcmarine@sbcglobal.net. It would be much appreciated.
Thanks

Vince

SSIs will cost you 20-30HP..... That setup config was only for old style heat exchangers on 2.7s. If your car is an 80SC you don't want SSIs with a turbo setup...unless its a twin turbo!!!

[jcc911]

T. please explain in greater detail why the ssi's rob power.
thanks

[tsuter]

Its all about speed and flow direction.

The collector is right under the turbo flange and the alternating combustion events from each side are fighting/opposing each other to make a 90 degree turn into the turbine. No place for a wastegate either without one side or the other completely having to overshoot the turbo or a very expensive three way joint. No valve overlap right...talk about back pressure....bad bad bad. The 20 HP you gained NA you just lost and more with a turbo. Unless its a twin.

This was a poormans conversion for the early style exhausts on 2.7s who wanted BAE turbo kits but did not want or could not afford to UPDATE to the SC style headers/heat exchangers that use the forward crossover and the collector merges the exhaust (TRAVELING IN THE SAME DIRECTION) infront of where the cat used to be.

Nice run to the turbo for speed and a good place for the wastegate.

Just look at factory Porsche 930 header/exchangers and see how they manage the exhaust flow to maximize speed to the turbo. Now Dansk and maybe another has a 930 (header only) setup that collects at the turbo...but its 38 or 40 mm primaries and has a three way collector at the flange to the turbo for wastegate, and left and right sides.

If you already have the SSI and exhaust backdate investment in your car I would still rip it out and sell them and get some nice jet hot coated stainless steel regular exchangers and fabricate an extension to mount my turbo off the end of a cat bypass pipe.

If you haven't already invested in SSIs .......then don't if you're doing a turbo.......

[tsuter]

Collection and flow direction like this ....is what you want.





Not like this.....



And the muffler(?) is just as bad doing a 180 wrap around... my apologies to who ever this set belongs too.

[mb911]

I disagree with the fact that the only way to do it right is use the single inlet flange style 3.0 exhaust. If there are diverters installed in the y crossover pipe then you can seperate the to impulse sides(seperate banks) with no issues. the wastegate can be easily seperated in the fabrication it would only be in the crossover. The advantage to the ssis is that the ID of the pieces are 2 each times 2 and the inside diameter of the sc stuff is 2.5 . what I am saying is that I think the ssis can be made to be better in the long run with a new cross over. No offense Thad I know you have a very extensive back ground in this but that is my theory

[tsuter]

I like this one....



or this one....



These are good designs...


But the one in the BAE kit for 2.7s posted up above was not efficient and robbed off a lot of usable power. It was just a pipe with a flange. You would not want to spend a bunch of coin on SSIs then bolt that thing on.

[vinny c]

Thad,

Thanks for the info. Still have the stock HE's w/Fabspeed installed. My crossover and muffler setup looks exactly like the pictures. So I'd need an elbow fabbed between the bypass and T04B turbo. I was hoping to modify my GHL 1in1out to keep stock look. I'm willing to sacrifice a few HP. What do you think?

Vince

[mb911]

Originally posted by tsuter
I like this one....



or this one....



These are good designs...


But the one in the BAE kit for 2.7s posted up above was not efficient and robbed off a lot of usable power. It was just a pipe with a flange. You would not want to spend a bunch of coin on SSIs then bolt that thing on.

Yes right on thad thats what I am talking about and will be fabbing up for the folks that want them

[jcc911]

But isn't the on pic (pjv's) the same thing just on a smaller scale. Underneath the flange, the pipe is diverted up to the TC from each H/E?