heliolps2

As some you know, I just put my 92 965 Turbo together and I want some extra boost, I don't really plan on tracking the car , but maybe an autocross or a few seconds on full on the road, The only mod I have is a FabSpeed Cat bypass. and thinking of a wastegate bypass in the future.

My old 76 911 GT clone 423HP 3.3 Turbo car had tial wastegate with 1.1 bar boost , and it ran a lot lean on top, It lasted for 15 years and countless track events and autocrosses and weekly drag racing.

These 964 Turbo are limited .7 bar, it seems to want more boost. Most people change the wastegate springs to up the boost, Why not a boost controller ? wouldn't a boost controller give more tuneability ?

What springs are most common to use on these cars ? Can I run 1.1 bar boost safely?

I want the car to look stock, It would be pretty easy to hide the controller, and easy to remove also.

Any ideas on a boost gauge that I can install temporarily for testing purposes ? Can I use the stock boost sending unit for a electronic gauge or would it be better to hook a Vacuum style boost gauge ? I could hook it up to a vacuum line somewhere? and which vacuum hose can I tap into? again for only testing and setup only.

Metal Guru

When you add air, you also must add fuel or run the risk of major damage to the engine.
You will get maximum performance safely by adding a Leask WUR, adjusting it to add fuel under boost and monitoring your resulting afr with something like a Innovate LM-1 or it's equivalent.
I'm a little surprised that you wound up the boost on your previous Turbo without any fuel enrichment and then tracked it. Since you didn't tear down the engine after all that abuse, I'm not so sure you really got away with it. I'd wager that you had damage to the piston tops and lots of broken rings.
I don't mean to be harsh but I wouldn't roll those dice. It's too expensive if things go sideways.
A former member here (a local guy who was an engineer and should have known better) put a compact K29 on his 3.6 without increasing enrichment and ended up dropping a valve, which destroyed the engine. He took a $100,000 car and turned it into a $30,000 car.
I have a boost controller back on the engine that's set at .8 bar. I also have a Leask wur and an LM-1 sitting on the passenger's seat. I have a VDO boost gauge in the change slot in the console. I find that with using a boost controller, the permanent installation of the gauge is necessary.
With the K29, SC cams and a lightweight flywheel, .8 bar is very entertaining.
I'm curious; how lean were you running up top?

heliolps2

I just went for a test drive and checked am AFR's as a base, 2nd gear pull 10.2 afr, shifting to 3rd 10.9 to 11.2, A little rich, and I have no cat,

I raised the idle to 1000 prm's to make for the drop when I turn the AC, saying that, It idles at 17.9 afr happily. my 930 3.3 idled at 13.5 to 14 afr. hnnn...... I feel that when I install the Manual Boost controller it should take care of the rich on boost, I dont to play with WUR or the SP, because runs perfect now, just rich on boost

heliolps2

After all that abuse, and it was abuse, I had a leak down several times by different shop over the 15 years my average leak down was 3% unbelievable, I have the leak down results somewhere and a dyno sheet, I'll post it.

heliolps2

here's one the leak down test, after 60k miles, like I said at least 20 DE's and dozens of autocross and may a few hundred drag races.. crazy no ****

Metal Guru

Remember when you run really rich you begin to wash the oil off of the cylinder bores.
So your 10.9-11.2 at boost being all in? What are you up top (6-6.5 K rpm)? AFR of 12.5 is still safe.
I think you need a Leask wur. Your afr's are all over the place. No manual boost controller will fix that.

heliolps2

here's my old car that I owned for 23 years

heliolps2

At 6000 rpm's I was still in the low 11's in 3rd gear, Not safe to go any faster on public roads at that point, I agree that 12.5 is a graet place be, I will do test as I go forward.

heliolps2

Here's my dyno sheet from my Yellow Turbo, crazy numbers .

Here's my second dyno pull #s , I adjusted my mixture a little from 14.5 to 13.9 at idle , the afr's changed a little to 13.3 an hp went to 346 and 399 TQ, but still really lean , I did not know at the time that I had a bad alternator, this is rear wheel hp, so add I guees add 15% for fly wheel HP and TQ numbers right ?

Metal Guru

Hmmm, 13.5 at 6600 rpm is in the danger zone.
I'm an anally retentive engineer so I would never go there.
It's your car, so you can run it any way you want.

heliolps2

That was my old car, I would not do that now, With this car, My goal would be to be the mid 12's, I dont plan on abusing this 965,

ralt

If you want to keep a nice car with lots of power and dont plan to track it then put in a 1 bar spring and boost gauge and be done with it. you are leading yourself astray by 'playing' with an adjustable controller. THERE IS ALWAYS SOMEONE FASTER

Metal Guru

"Leading yourself astray"? Don't you mean he might succumb to temptation?
An adjustable controller is not for the ignorant, for sure.
I use one purely because I'm lazy. I have two wastegates and to tune them swapping out multiple spring combinations to get the desired boost is a lot of work. I also understand the ramifications of turning the boost up (more boost required more fuel) as I'm near the limit of what my stock CIS can supply. BTW, I run at .8 bar and I have "enough" power to keep me entertained (for now, anyway).
I would recommend headers and .9 bar, then verify the afr at whatever redline you want to run to up to the limit. One way to make your car feel faster is to drop the boot onset point, which headers do nicely.
One bar with a stock K27 is ineffective as that is over the choke point of the compressor. All your doing a that point is pumping hot air into the engine. You won't feel any difference there.
Bottom line is this; if you don't want to have to do any tuning, leave your engine alone. Anything beyond requires verification of AFR's at minimum to avoid making an expensive mistake. Increasing enrichment through a Leask wur or switching to EFI may be necessary, depending of power level desired.

urquattro20Vt

I, too, am a HUGE fan of the Leask adjustable WUR. Even if the motor was stock. Adding a little boost only increases the necessity IMO. I have a boost gauge that I keep out of sight and just check to see if things look like they always do - Which begs - ** what vacuum do you guys see at warm idle?** And I have an AFR gauge that I look at periodically - again just to make sure everything looks normal. I run a 1 bar spring. I think that's a good way to go. Not a fan of boost controllers for some reason....but that's just me.

Enjoy that car!

heliolps2

Ok, I installed the Manual boost controller and hooked up an boost gauge and my hand held Innovate AFR unit and did some test runs, the first run I hit the over boost, I dialed it back a little, It seems to hit the over boost at 1.1 bar 0r 15 PSI, that was in second gear, WOW what a difference, I set it at .9 bar but she kept blowing the rubber hose off the turbo to the intercooler side, I have it fixed now, I think..... After removing the intercooler 4 times . She seems happiest at .9 bar like Paul B said, Along with the cat bypass she feels great, my AFR's in 2nd gear at 6000 rpms 11.9. fuel doesn't seem to be a problem. I'll have to more testing in 3rd and 4th gear pulls.

Does anyone know what kinda horse power gain we get at .9 bar and a cat bypass ?

Question... Is there any benefit by installing a wastegate bypass pipe. beside the great sound ?