Why Are Turbos Unwanted - Page 8

yasir · 05-18-2005, 01:33 PM

Quote:

Originally posted by BlkBird
And that nets 389 HP at the rear wheel! With 425 ft-lbs of torque at 4400 rpm.

Blkbird,
I know several C2 Turbo owners who made right around 320 rwhp/low 300 rwtq with the same mods that you have minus the IC,makes me wonder if just an IC would net someone 70 rwhp/100 rwtq ?
Did you ever get your car dynoed ? Can you please post the dyno graph ?

BlkBird · 05-18-2005, 01:47 PM

Yasir,

Yep, this data comes right off the dyno. And while I understand the intercooler is worth some HP, I couldn't say how much. More likely it is meticulous nature of the shop that did the work.

Matt is the consumate professional and I know the car spent two hours on the dyno while he adjusted fuel/air ratio over the rpm band. Apparently he could have gotten more HP but at the expense of torque and i am pretty happy with what he has done. I have the dyno graph but would need to scan it in order to post.

Also interesting to see the K27 7200 lose efficiency above 5500 rpm or so. The HP actually drops a bit above 6000 rpm. Apparently we can tweak the turbo to stop that but my budget is in recovery mode right now.

One thing about this thread - 930s can be expensive. But it ain't the 930 that costs, it's the quest for HP. I think we can all agree that any HP gain is addictive and expensive.

yasir · 05-18-2005, 02:06 PM

Blkbird,
Can you please forward me the info about the Matt's shop as i myself is pretty interested in getting some ponies out from my C2 Turbo too.I have been looking for a shop thats not too far from KY yet competent enough to know what they are doing ?
O btw do you know David who owns a red 1991 C2 Turbo and a black ferrari 355 ?
Thanks

rick conrath · 05-18-2005, 02:10 PM

How does reliability factor into any high horsepower situation? It doesn't. Reliability and horsepower are oxymoron's. I have considered a NA 3.6 transplant ( I have a v-ram long block on my garage floor), but I am "personally" ( I said personally) not satisfied with 265 -280 rwhp for the expense of the conversion, or the easy 300 hp at the crank. It's not easy!!!!!! Compare the true costs to upgrade a turbo vs NA engine to "high horsepower" values if you want a real comparison. Forget the turbo lag, reliability myth. They are non-issues if you know what you are doing.
Rick
'78 930

911teo · 05-18-2005, 02:29 PM

Rick all I am saying is that it is very expensive to get a 3.3 turbo to dramatically outperform a stock 3.6 on the track.

The turbo can be made lag-free and reliable and can be made very powerful. It's just that I suspect all this cost more money than the 12k that you need to swap out of a 3.2 into a 3.6 vram.

Tha'ts all.
And it is easy to get 260-280 rwhp (read 300 HP at the crank) with a 3.6 Vram... just check this BBS, there are plenty of examples.

Personally (again it's just me) I would have changed the pistons, fuel management, intercooler etc to get 400 rwhp from a 930 engine.

Now blkbrd says you can do it with $5k (with turbo efficiency problems above 5500rpms)... That makes me wrong.

I was just trying to answer why one would decide to go the 3.6 n/a route vs the 930.

BlkBird · 05-18-2005, 03:05 PM

Matteo,

Don't forget that the K27 7200 comes on early too. I start seeing boost around 2500 rpm.. but like i said it drops off around 6000 rpm. And it is not just a matter of bolting the parts on ($5K) - there was a considerable cost for labour too.

But that labour included changing out almost every vacuum hose and electical wire in the rear - or so it seems when I looked at the work. Hire a guy who builds race cars and close your eyes when you write the cheque!

yasir · 03:45 PM

Imagine auto out of KS has come up with a new version of K27-7200 called K27HF-S that flows lot more air and is able to maintain the boost all the way to the red line too.

Jeremy Cottrell · 05-18-2005, 04:08 PM

Who wouldn't want this??

Emission · Emission's Garage

Quote:

Originally posted by yasir
Imagine auto out of KS has come up with a new version of K27-7200 called K27HF-S that flows lot more air and is able to maintain the boost all the way to the red line too.

A reason to look forward to the death of my K27-7200?

350HP930 · 05-18-2005, 05:08 PM

I have moved beyond the K27. Its the garrett GT37 for me at this stage of the game.

If any of you HP junkies are in need of turbo parts, I am selling my K27-7006 to anyone who needs a rebuildable core.

RarlyL8 · RarlyL8's Garage

The most basic common tried-and-true modds for the 930 are:
- Turbo upgrade, usually K27-7200 or K27-HF. $1200
- Exhaust/headers, usually B&B or the like. $2500
- Larger intercooler. $1500+
- 1.0 bar spring. $50
- Cams, usually SC, 964, or like grinds. $400

This formula gets you from 375-400HP at the wheels without breaking the bank. That is the route I took with the Posermobile. It's never been on the dyno and may never be. It's so damned powerful with the short gears that I DETUNED it back to the stock wastegate spring. This car was gonna kill me if I didn't back it off.

Yes, a good driver in a 3.6L powered light 911 could take me at the track easily. I suck at the track.
There are good arguments for both forms of power delivery. If you want a torque monster as a daily driver that gets good fuel mileage then it's the 3.6 hands down.

350HP930 · 05-18-2005, 06:49 PM

That's a good point about detuning Rarly .

One of the mods I made to my wastegate was cutting the spring so I have the option of running a minimum of 0.5 bar boost.

The project is not even done and I already realize I will need a lower setting than before to keep me out of trouble.

I may have to invest in a new set of rims to upgrade the rears from 275s to 315s at some point though.

Emission · Emission's Garage

Quote:

Originally posted by RarlyL8
It's so damned powerful with the short gears that I DETUNED it back to the stock wastegate spring. This car was gonna kill me if I didn't back it off.

I also removed my 1 bar spring and went back to stock for two reasons:

1. California gas is only 91 octane. My engine was pinging.

2. My 0-60 time is already 4.97 seconds with a gentle launch.

I don't need more speed right now, and I will enjoy better engine longevity at lower boost levels.

mmastro · 05-18-2005, 07:27 PM

Amen to that!!
I have the 0.8 bar stock spring and don't need anymore HP...My abilities have to catch up to the car's at this point...MORE TRACK DAYS!!

Craig 930 RS · 05-18-2005, 07:37 PM

Your engine will live much longer at .8 than 1 - I'm happy with my 418 RWHP at .8 ----

Shuie · 07:53 PM

Craig doesnt want a turbo

Craig 930 RS · 05-18-2005, 07:59 PM

?

Shuie · 05-18-2005, 08:29 PM

Just kidding. I cant imagine having 400hp on tap. The old car was pretty amazing but you are going to have a lot of fun in the new car.

rick conrath · 05-18-2005, 08:46 PM

Since a well prepped 930 can be made virtually lag free, what about the turbo configuration make it so bad for the track? Sounds more like something that time behind the wheel could solve.
Rick
'78 930

Emission · Emission's Garage

Quote:

Originally posted by rick conrath
Since a well prepped 930 can be made virtually lag free, what about the turbo configuration make it so bad for the track? Sounds more like something that time behind the wheel could solve.
Rick
'78 930

I think it's the heat.

Turbos generate tons of heat, and dissipating that heat gets to be a ***** after time. A bit over a year ago, I took my 930 to Death Valley (there is a thread about it here somewhere). After several hours, there was so much heatsink that the intercooler was cooking. With ambient temps in the high 90's, I just couldn't get it cooled down and my 930 was a dog. I'd imagine I could have prepared for it with a larger intercooler and better airflow... but a NA car wouldn't have to take those measures.