1988 930 upgrades
 

I have a 1988 Porsche 911 turbo. It has the following upgrades:K27 turbo, Garretson intercooler, Borla quad exhaust, 1.0 wastegate spring and 18" O.Z. racing rims.I had it rear wheel dyno tested and it showed 305hp and 302 tq. At the track, My best run with a relatively soft launch was 13.2 at 109.5mph. I estimate at the flywheel 360hp. I would like to upgrade to the point where I will have 450hp at the flywheel, or approx. 400 rear wheel horsepower, and a low 12 sec 1/4 mile car. I am considering headers, camshaft(group b cams), fuel enrichment, a possible larger turbo,adjustable boost and even a change to a 8:39 ring and pinion for better off the line acceleration. At the same time I don't want to decrease the life of the engine and I want to maintain a semblance of streetability. I have numerous friends that have Vipers and Corvettes that are low 12 second cars and although I can keep up in top end, unfortunately I lack in off the line performance. May basic question is would these modifications achieve my goals and if not, would modifications would?Also, if someone out there has done similar mods on a similar turbo, what perfomance,and reliability was achieved, as well as costs incurred. Thank you in advance.

Hi Chris:

Since we done quite a number of street Turbos that average 450 HP on our engine dyno, may I offer some general suggestion about how we got there?

First, I would strongly suggest not using adjustable boost unless you have a serious budget for engine overhauls. Use no more than 1.0 bar and .8 is best for longevity. This changes exponentially with boost pressure.

Second, be aware that other limitation is octane grades and and stock Turbo, much less a modified one, will knock on 92 octane fuel in hot weather under load. Use the very best you can find.

Here's the general recipe for making an honest 450 HP 930.

1) Use 98mm P/C's with 8.2:1 CR. The OEM P/C sets do not last long due to poor cylinder cooling. They have no fins except on the bottom.

2) Heads and intake manifold must opened to 36-38mm and all ports flowed and matched with each other. You will need larger, alloy injector blocks, too.

3) Install the B&B header/muffler system for reducing turbo lag and cylinder head heat.

4) Install SC cams

5) Use the K27-200 turbocharger

6) Larger intercooler. I prefer the Factory C2 one.

7) I replace the stock rod bolts with ARP or Raceware ones. In many cases, I also install racing valve springs and titanium retainers. This is all done for strength and insurance. There are no power gains here.

8) Aircleaner cover mods. Drill 6-7, 1.5" holes at the bottom of the stock air cleaner cover. Don't waste your money on the Powerflow device.

9) Twin ignition. Not cheap but absolutely necessary. Machine your heads for the lower plugs and have your stock distributor converted to RSR spec. Add a second CD and coil; Bosch or MSD.

10) Have your CIS airflow meter and fuel distributor modified for more fuel flow. This is critical for engine longevity. The stock setup is too lean and the various aftermarket fuelers are not needed.

This makes a very powerful and torquey 930 that will live a very long time IF this is all done properly. Its assumed that you will have already installed adequate oil cooling to dissipate the additional BTU's.

Install some close-ratio gears and you will have a formidable machine, :D

Hope this helps,

I like the advice Steve provides - Although I think he is building in a big margin of safety, I really can't argue with any part of it!

Better to be safe than facing an expensive rebuild.

Now Steve, what do you mean by "live a very long time"?

In ballpark figures, what do all those modifications cost?

Thanks
Jeff

Hi Jeff:

What I mean by safety is: Durability and Longevity.

People who buy these cars expect the power train to last a long time. After all, this is one of the reasons why one buys these cars. Engineering & quality are some of the endearing things about Porsche cars and modifications that adhere to that are, IMHO the only options. No matter how much fun something might be, not many people are willing to to put up with a "hand grenade" in terms of durability.

These cars are so bloody expensive that it would be irresponsible IMHO, to offer any power upgrades that reduced the reliablity that Porsche built in. From my perspective as a tuner and builder, my name is on everything we do and I must deal with the end result,....... :)

Its not hard to get big power from these cars, its NOT easy to achieve those same results and maintain the same longevity that Porsche delivered when new.

Given how Turbo's are driven, its very difficult to state uncategorically how long these engines should last. We do have some clients with over 75K on their 450 HP 3.4's with no troubles. This is of course, with excellent maintenance and proper oil cooling capacity.

From a cost standpoint, the last few 3.3's that came here for rebuilds that were configured as my above list, those were in the range of $ 18-21K for all parts and labor for the whole thing including a light weight clutch setup that we do to handle the torque.

This kind of power doesn't come cheaply when durability and longevity are an integral part of the equation.