MarinS4

Will be way north of 500hp soon.

Tuner1

Nice work....but what a tease! Pics with no specs or details?

It looks like you are running oil through the water cooling jacket on the turbos.

I would really like to know more about your heater set up. Are you taking heat from a custom box around the muffler?

MarinS4

993 NA varioram motor, GT2871 56trim turbos, 40mm tial wastegates, dual CDI ignition, seimens 60lb injectors, 996 turbo check valves, tial oil restrictors, stock bottom end running 6psi of boost. approx 450hp.

Putting together the parts to build 700-800 HP monster. Talking with Colin about the 9M heads. Will work with Geoffrey on cams. Pauter rods etc. The rest of the supporting hardware is already in place to support those power levels.

Yes we welded the cooling inlet fitting and drilled it out with 2mm bit to restrict oil flow. Have been doing for years on 993tt's and have had zero turbo failures to date.

Heat is pulled from around the muffler via custom box. Not a lot of heat but enough to keep the windows clear here in NorCal.

Tuner1

Bad ***! Do you need to deal with Cali smog tests?

Good choice.

Sounds like a good idea.


I would love to see more pics of your heater box set up because I need to fab something similar for my car.

Guns951

Any form of a compliment or even criticism coming from you Jean is always welcome! But quite frankly after living with her on the street - driving her every day and doing a long haul on the road from one part of the US to another - its like sleeping with Heidi Klum every night - after awhile she's just normal to you. Which is why I just bought a fresh caged and acid dipped tub to put my Kremer K3 bodywork on and move this motor into that car hoping to get her down to 2100 lbs with a partial tube frame.

We tried to log some 60-130's when I got back to Texas but I kept getting wheelspin as soon as I'd go past 70% to full throttle - so about 65% throttle is all she can take before roasting the rears which is fun especially at 120. We paint marked the tires and noticed that I'm spinning the wheels inside the tire even after having them mounted with hair spray to keep the bead. Then when things started to look good, the clutch decided it was time to obliterate itself...and I was really good to it .

Maybe the difference lies in the transmission? But if anything with my stock geared 4 speed box should make it harder to spin them....

It was insane when I picked the car up from the shop and super experienced and totally cool shop owner from Zuffenhaus took me for a lap of the town on the highway with him behind the wheel, he hit full throttle at about 4,500 rpm in 2nd and kept it pegged to 3rd and all she would do is rev up super quick, you could hear the rubber thrashing around and see the white smoke trail behind the car....we thought we trashed a turbo or the pressure plate was slipping - until he did the same thing at 3500 rpm in 3rd...then the rear lit up like the 4th of July and you could hear the tire protest and smell the burnning rubber all the while being propelled forward so fast we were both pinned down like on the space shuttle...at which point we were both reduced to sheer expelitives and giggling as we still managed to top out 3rd gear and some highly excessive speed.

I'm just hoping to learn more about these motors from all you guys as begining a retune I want to make sure I take advantage of everything I possibly can without losing any power or that intoxicating sound. Its nice to see the rest of the high hp 3.8's start coming out of the woodwork.

TB993tt

I reckon this wheel spinning thing is more a sympton of ramp up of boost/steepness of torque curve (onset) than actual peak torque number.....

On my first 993tt build I had RSK24/26s which were a new design at the time (used in the 993GT2 racers of the day for 620PS/830NM and gave a much better bottom end than the K26 external wastegate jobbies which were race turbo of choice IIRC) and the boost ramped up very quickly from ~3800rpm to maximum T at 4500rpm peaking at 760NM, the onset of this boost/torque would spin the tyres quite easily......

My last build was 3.8 higher CR and more modern 24/26s from the 996tt era and the boost would come in much sooner at 3000rpm and peak at 4200rpm at 800NM and despite the higher peak torque, because the boost built more gradually the delivery caused much less traction issues, there was less of a longitudinal G spike which is what causes the traction loss.

Fast forward to latest tech VTG turbos with variocam, boost comes in below 2000rpm and peaks at 3000rpm (830NM) then stays near constant in the 800NM range until 5000rpm and the traction is simply staggering meaning the torque can even be deployed through 2 tyres on damp roads, it seems other worldly the way the torque can be deployed but it is this smooth delivery which doesn't cause the G spike.

So in summary I reckon it is your big turbos lighting up like a light switch which is a diifficult thing to do anything about (short of rebuild with higher CR and bigger capacity then fine tuning to bring the turbos on soon as possible), but I'm sure its fun

MarinS4

TB I understand exactly what you are talking about. In the last build I did the power deliverly would come on hard and fast spinning the tires through 3rd. Driving on the track you had to be careful where you tried to put down power. This latest version (high compression low boost) the power is delivered very smoothly and never upsets the chassis.

Guns951

My turbos are small compared to the 935 snails - T4 hybrids actually with .63 hotsides and 8.5:1 compression. I can peg full boost by 3400 RPM though and I think you're right that is what's causing the traction issues.

The shop wants to do gear dependant boost and institute a form of traction control which i'm soo against. So if I'm wanting to enlarge my snails for a higher hp goal - are electronic nannies the only way to get there?

MarinS4

Guns.....I agree with your shop. If you do the apexi AVCr you can vary boost by gear and RPM on one setting (A) and still have one boost level on the other setting (B)

TB993tt

Must admit I am for the elctronannies also

After having my 993tt in RWD for a while it just wasn't fun driving on cambered damp UK roads and a stock 993tt would probably been faster point to point (well probably not but certainly much safer !)

My first taste of elctronannies (drove the 993tt 1996-2008) was the Carrera GT with its TC courtesy of ABD and elctro and even this was an accident waiting to happen... I feel with 2WD and 700+NM the electro intervention is the way to go - with the 7GT2 it just makes it a more fun drive and what really rams it home is when the TC/PSM light flickers when you at WOT going around a slight bend and hit a camber - makes you realise that if it wasn't for the help you'd be in the hedge or worse !!

BTW Guns.... love the 935 look, just read your specs - perfect

Basal Skull

I don't think I have anywhere near the experience or knowledge as you guys but isn't it the advantage of ecu/motronic the ability to limit boost at peak torque and having full boost at a lower rpm is not what's required for max overall performance? To get the smooth power delivery the boost needs to be controlled quite a bit at peak torque and increased at higher rpms? I guess that's the advantage of motronic controlled boost?

When I briefly changed ecu's (tried to a non boost controlling/ecu requiring an external boost controller when I was having difficulty with my ecu), I know my turbos could give me >1.4 bar before 3500 rpms or so but with my proper ecu (now fixed), at 4000 rpms, it limits it to 0.6 or so bar. And only gives me the higher boost value at higher rpms/full load in 3rd and 4th gear. My power delivery is pretty smooth.

atan888

Future member checking in

https://rennlist.com/forums/993-foru...-take-2-a.html


Alvin

Woodster

TB,

Long time no chat! Would love to hear more about your new GT2 some time.
Question: have you done the 60-130 or 100-200 runs in it and if so what are they with the RS Tune? Just sold my 996TT after 4 fun years of ownership which followed 2 years with my 993TT, etc.

I really like the 997 platform and hope to try that next with either a GT3 or
997 TT. I was lucky enough to ride in Sharkey's ZKermit 997 GT3 3.9 liter
a month ago or so and its sound and free revving motor were intoxicating to say
the least. I will include a picture of sold car and Sharkey's car just for fun.
Sorry for the OT guys, but I am really missing my P-cars already

vincentdds

Future? Past and current as well.

Al Pettee

Yes, Alvin, now get that baby completed and on the road.

The wait is killling even me!

I've been following your thread on 6blingonline ad infinitum.