Porsche Archives - Page 2 of 2 - Promotive Engineering

Every kid’s dream – a 935 K3!

November 23, 2016 by Promotive Leave a Comment

When I was a kid, my bedroom walls weren’t lined with posters of Pamela Anderson, they were lined with posters of the all conquering Porsche 935s. And ever since I have wanted one. Or more to the point, I needed one! Watching them breathe fire down the Mulsanne Straight at the Le Mans Classic a few years ago really didn’t help my need either…

Meanwhile, I have been wondering what to do with a car we affectionately call Cupcake, an ex-Porsche Cup racer. Being built on an early model shell that is in unbelievably good condition; and the ever increasing values of the long nose cars; the smart move would be to restore it back to standard. I have never been that smart, so I ordered some late 935 K3 panels and hunted around the workshop for the angle grinder…

Removing the existing 930S body kit was quite cathartic! I don’t know what Porsche was thinking when they came up with the slopenose body in 1981 – it has always been a bit embarrassing, it is like the ugly lovechild of a 944 and a 930 – and no one likes a 944! Then again, it could be argued that painting it a three layer pearl pink could also be considered a bit silly. I was young…

It was like Christmas came early when the kit turned up! It was pretty painless compared to some of the other kits I have ordered for customers. I had to sit the panels on the car to see how much work was ahead of me. As you can see from the photos – a lot!

The one piece nose is going to be pretty straight forward. Unfortunately the existing splitter isn’t a good fit so a new one and matching flat floor will need to be laid up. The rear is a bit more complicated. The panels aren’t too bad but I want a fit that is better than the average race car so it isn’t going to happen overnight. A 935 is 2 meters wide and in original form ran 19 x 16 inches wide wheels so it makes the existing 16 x 13 inch wide rear wheels look a bit silly. Heck, it looks like some really bad quality VW kit car at the moment! I better sort out some decent sized centre lock wheels. I really need some old school centrelock BBS wheels with the fans…

935-k3-mockup-side

Motorsports can be so frustrating!

November 9, 2016 by Promotive Leave a Comment

So, so frustrating!

Targa Tasmania was going so well for car 806 until an unfortunate overtaking accident left made a mess of the car…

After all sorts of delays with available panels and parts, I finally got the car back here with only three weeks to get it ready for the event, Targa High Country. While the panel shop did an amazing job of straightening the shell out (everything fitted and wheel aligned / corner weighted perfectly); it wasn’t just a case of bolting it all back together. On top of the normal pre rally prep and a couple of upgrades, there was fire damage to the wiring loom, impact damage on every corner where every bracket and part needed replacing or repairing, as well as repairs to the engine and exhaust, crack testing and inspections for the gearbox and drivetrain.

We got through the job list in the limited time available. The car even had time to get a new wrap job and a test. Even the air conditioning was re-gassed! I finally caught up with some sleep thinking we did a pretty good job!

That was until I got a call from the event… After all that work and late nights – the fuel pump randomly decided it was time to stop working! It wasn’t even that old! So frustrating – who would have picked that to fail!

And yes, I have CAD drawn up a new fuel tank top insert for a dual pump upgrade before the next rally…

Porsche dyno testing

December 5, 2015 by Promotive Leave a Comment

It seems like I have been spending a lot of time testing fuels these days! I have tested the ETS Extra Max fuel in most of the standard late model Porsches to see what sort of gains can be made just by pouring in the oxygenated race fuel. The various Bosch ECUs respond well to the fuel and the gains have been at least 30hp at the wheels with no other changes made. On cars that have the ability to retune and add boost then the gains that can safely be made are significantly more! It is cheap power and great for track days…

996 Turbo Dyno Porsche 996 ETS Graph

Testing on the chassis dynos has been a great way to check the tune and show the relative gains to be made from the fuel but using a ‘rolling road’ can be a bit problematic. There are drivetrain and associated losses through the tyres, inconsistency with overheating tyre temperatures (particularly with race rubber), wheel spin and the electronic diff controls on some of the Porsche four wheel drive models just don’t get on particularly well with some dynos…

An increase in power is one thing, but what doesn’t don’t show on a dyno graph is the increased throttle response which gives that extra punch out of the corner, and sound of the engine is so much smoother!

I have been using my engine dyno to do a fair bit of comparison testing too. It is no secret that I have never been a fan of premium 98 fuel, the lack of consistency from the pump has always scared me. It is Ok on a car with a factory ECUs that have closed loop controls that wind back the timing when detonation is detected, but on highly strung engines that are used in competition – it is a bit like playing Russian Roulette. Using the repeatability of the my engine dyno, I did some back to back tests comparing P98 fuel to ETS Extra Max. The engine I used was a relatively standard air cooled 911 turbo engine. Like most 911 turbos, it doesn’t have enough airflow over the intercooler so has high inlet air temperatures, and it has the same problem with the oil cooling, particularly after a few laps at the track on a hot QLD summer. It is the sort of engine that is a bit scary on P98 with any reasonable amount of boost.

The graph below shows the runs from the two fuels. Obviously the line labelled ‘Hp(1)’ is P98 and ‘Hp’ is Extra Max. It is a pretty huge difference and the only change I made to the tune was trimming the fuel sites on the Motec M800 to make the lambda about the same. The blue line is MAP pressure so the engine is just running on waste gate pressure for this test.

The engine with a bit more boost. Unfortunately it is running out of airflow but it does have very conservative cams and heads…

ETS ExtraMax boost

And this isn’t the worlds most exciting video but here is the engine in action…

Ceramic Coating – bling with function!

November 24, 2015 by Promotive Leave a Comment

I have never really understood the appeal of chrome. It really only points out that the part hiding underneath is low tech, over weight and its only trump card is that the part is shiny. You could argue that it prevents corrosion on ferrous parts but there are a lot of better options.

One of those high performance options is cadmium plating which has all sorts of great additional properties such as prevention of galling and a neutral galvanic coupling when used with dissimilar materials. I guess that is why Porsche used it so much in the past and why it is still the coating of choice for aviation. Unfortunately is becoming more difficult and expensive to use.

One of my other favourite coatings is ceramic. As seen in the photos, it has a lot of bling to it but has the performance to match. It isn’t only for exhausts systems, I use it for other external parts like aluminium manifolds and internally on piston crowns, combustion chambers and valves to encourage more heat out the exhaust.

The photo of the valves above show one pair that is coated next to the uncoated spares. The beautiful swirl polish finish of the custom valves is gone but heat reduction into the valve is measurable. The intake valve is cooled by the intake charge so it is normal just to coat the combustion side. The exhaust valve has a harder time so coating both sides can be an advantage and take some heat away from the guides. The same goes for the pistons like the GT2 pistons pictured above except a dry film lubrication is applied to the skirts. The coatings on the pistons are such an advantage that I don’t build engines with out the coatings these days…

I just had to include a few photos of the Lycoming 540 cold air induction manifold I just made and had coated. The thing is a monster! It looks like a giant spider – well, a spider that only has six legs anyway… It has injector bosses for calibrated injectors to be fired by a Motec M1, as opposed to the ridiculously basic aviation injection that makes K-Jetronic look like something out of Star Trek; tapered tubes, bellmouths in the plenum and all of those little details that take ages to fabricate and aren’t really seen! The Lycoming cylinders are not crossflow so the exhaust is in very close proximity and the entire exhaust and intake manifolds are therefore coated. (The picture of the merge collectors above are for the same engine).

GT2 v2.0…

July 6, 2015 by Promotive Leave a Comment

The GT2 is progressing. Slowly. It looks like it is still only half a car, but it will be twice the car it was…

Unfortunately, the panels that we ordered were the worst quality I have come across in twenty years so a considerable amount of time has had to be spent on getting them to fit. I really want to make the rear panels clip off in one piece but I am behind schedule already so I cant deviate from the brief… At least the front is mainly fitted up and I am just need to keep the CNC running to make all of the little brackets and smaller parts.

While the rear firewall and panels are not yet finally mounted, it is easier to do the plumbing and mount the suspension. The rear links will be fitted in the next week so the new engine can be fitted and the turbo manifolds for the EFR turbos fabricated. The intercooler will be fed by the massive air scoop that was used previously so that can be fitted at the same time. The engine can be then dynoed and fitted…

There is still a few long days ahead before it looks like a car again!

Dyno upgrades

July 2, 2015 by Promotive Leave a Comment

I have been busy lately on a few big builds and have managed to find some time to do some upgrades to the engine dyno that I have been wanting to do for too long. While some of the upgrades are purely practical and allow engine changes to be quicker, I have also added significant over capacity to the cooling system to engine temperatures can be optimised.

I have become really interested in the fuel testing lately and comparing different race fuels. I have added a flex fuel sensor to the dyno now which show how the ethanol content some of the cheaper competitors race fuels have and the consistency (or lack thereof!) ! It is a cheap way for them to increase knock resistance but it isn’t the best way of producing power…

I have upgraded the knock sensing in the cell as well. In addition to the two channel Vipec knock amplifier and headset, I have added a dedicated vibration sensing module. It is now easier to fine tune the knock sensors on a setup so there is less false readings and make it easier and faster to setup individual cylinder tuning. The new system will also analyse the vibration signature of an engine over time (FFT) and will show well balanced the engine is and the point of the imbalance. By looking at the spectral analysis you can distinguish the imbalance from a weak cylinder, a clutch or the cooling fan etc. Cool stuff!

Just need a more room on the console for all the readouts and instrumentation now! Maybe a lounge chair as well.

Feeling Blue. Not with this RS Tribute!

May 4, 2015 by Promotive Leave a Comment

This photo will be recognisable from the main page of my website perhaps. The wheels on this RS Tribute really were so spectacular that my (very) armature photography skills couldn’t really capture the gloriousness of the detail when seen in person. They really set off what turned out to be a very tidy 911!

The wheels were 15 inch Braid RSR style wheels but these ones are not the standard finish as supplied by Braid. They were stripped, anodised and dipped in paint to create perfect paint edges and then the lips were polished to give the final touch. I think they have turned out nicer than the Harvey Weidman wheels… Of course, the venerable Michelin TB15 tyres completed the look.

The sad thing about having such nice wheels is that the stunning RSR replica brakes were hidden away! I completely rebuilt the suspension and vapour blasted the arms before replating everything, fabricating some RSR style sway bars and fitting the 2.8RSR brake kit from Zuffenhaus. The calipers are stunning! The shocks were revalved to match the new spring rates and the result was a bucket full of fun!

A Tilton pedal box was mounted onto a reach adjustable mount so the correct pedal position could be found and the brake balance could be perfected. The pedal box was hidden under a custom carpet set and everything that a modicum of shine was powdercoated satin black.

The aim of this car was to have a fun toy for the weekend but it also turned heads everywhere it went!

Mexico Blue is such a striking colour!

Why I love my engine dyno…

April 7, 2015 by Promotive Leave a Comment

I have to agree with anyone that says that an engine dyno is not the most convenient tool to use. Even though mine is setup so a 911 engine just slides in to the cell, it is still a bit of a nightmare when it comes to the late model engines with complicated wiring looms. Obviously, it is only really useful if the engine is already out of the car but when it comes to control and accuracy it can’t be beaten. No problems with keeping the engine and tyres cool and no crawling on the floor to try and tie the car down. It is simple to make hardware changes because the engine is easily accessible.

It is all a trade-off I guess, and the chassis dyno I regularly use has always yielded great results for tuning and quickly diagnosing problems.

To comply with the new and ‘improved’ Porsche Club QLD motorsport rules, each competitor has to pay to have their car tested on one of only three hub dynos as selected by the club motorsport committee to get an uncorrected power figure. That figure then has a specified drivetrain correction applied to finally get a flywheel power to weight figure for handicapping. I am glad national championship events aren’t as complicated! The fact that two of the dynos are owned by committee members must be purely coincidental of course…

Anyway, this post is just a warning to competitors using the hub dynos so the same mistakes are not made.

Mistake number 1. If you have long wheel studs, make sure the operator that is bolting the car to the hub makes sure the studs clear the dyno! It was a hell of a racket, kind of like when you used to put a plastic strip in the spokes of your bike when you were a kid – just a hundred times louder! And not as fun. I wish I could have at least watched the car being being bolted on. Also, make sure the rear guards can’t hit the Dynapack casing if it hasn’t already been removed. It is awfully close on an old school widebody 911!

Mistake number 2. Don’t visit the dyno on the day of the event in case there is a problem. Forget trying to be efficient. You can see from the photo that the next drive for this car was back into the workshop for some new long studs and probably a new hub and bearing now the studs are loose. It was a pretty expensive day – a wasted entry fee, a repair bill and a lot of wasted time!

I guess this needs to be done any time a change is made to the engine too.

The next car to visit the club approved dyno has centre lock wheels. It will be interesting to see how that gets mounted and how much of my day it adsorbs. If nothing else, it will be interesting to compare the dyno charts from my calibrated engine dyno with accurate weather station to the club specified testing procedure…

Who said club motorsport was meant to be fun!

GT2 Update

April 4, 2015 by Promotive Leave a Comment

The The GT2 shell is back from the sandblasters! I have finished all of the major fabrication at last.

It doesn’t look like much at the moment but after a splash of paint and the composite panels are bolted or bonded on, it might actually look like the Porsche it was. Just a lot lighter, stiffer with better suspension geometry!

The new engine is going back together at the moment and should be on the dyno in the coming months. As in its previous incarnation, the engine is controlled by a Motec with one of my lightweight tefzel looms which saves just over 60kg compared to the factory loom and all of the various ECUs! This engine has some trick bits inside with a couple of Borg Warner turbos that I have found to be the performing turbos at the moment. More on that later…

Interestingly (to me anyway!) the chemists at ETS Race Fuels in France have recommended ESR GC4 as the fuel that has the best burn characteristics to suit this engine spec. It will be interesting to do another fuel comparison on the dyno. The gains by switching to the right fuels so far have been nothing short of amazing!

I can’t wait!