Porsche race preparation Archives - Promotive Engineering

More GT2

February 5, 2017 by Promotive

The GT2 has been moving ahead at a glacial pace! There is now a renewed push to get this car finished and on the track, so I dusted the cobwebs off the chassis and finished off the rear wing and engine mounts and a lot of those fiddly jobs that take so much time yet are never seen.

I decided to keep the turbos in a reasonably standard position but just make the headers so there was enough room for the external wastegates. It is a tight squeeze! There is just enough room so they don’t become intimate with the massive wheels when at full bump travel. It is simple and more efficient compared to the standard Turbo pipe work. The intercoolers have an o-ring seal onto the larger GT2 drive by wire throttle body to make mounting simple and the location is perfect to take advantage of the big roof mounted air scoop.

I am not looking to the next jobs of fabricating the fiddly firewall infill panels, replacing the firewall template with a carbon one with rear window, and then trying to work out how to mount the widened rear body work. It will be exciting to see it looking like a car again though!

Never enough room in the engine bay…

February 2, 2017 by Promotive

The current 911 trend of backdating and Singer look makes life hard when you are also trying to squeeze a couple of turbos under a ducktail or electric wing. I am a huge fan of a normally aspirated engine with throttle bodies or flat slides, but sometimes you just need more power and bigger flames. With a Masters Degree is Tetris, you can get a decent size intercooler to fit without needing an aggressive tail (as seen in the photos below of previous projects). The problems are compounded when you are trying to increase drivability by using long intake runners, and then need to find room for an air conditioning compressor.

The other option is to use water to air intercoolers. These are quite effective in a road going 911 because there is enough thermal capacity in the system to sink the heat generated by relatively short bursts of power, and the average road speeds are less than on a circuit so where the airflow over an air to air intercooler comes into its own. A current project uses twin barrel intercoolers on a twin turbo 3.4 engine arranged so there is ample room in the engine bay for easy maintenance and an electric C2 wing. The base motor hasn’t been touched so there hasn’t been an opportunity to tidy the old muffler up and detail the engine. Unfortunately it is function before form on this build…

The engine is being run by the enormously capable Vipec Thunder ECU. That allows me to data logging everything from EGTs, dual lambda and every pressure and temperature we can think of. One advantage of having so many inputs and outputs on the ECU is being able to take over the control of the electric tail to make it heat and speed dependant; and more importantly use a drive by wire throttle body. I try and use DBW on all the projects here these days, the simplicity in setting up traction control, and idle control make me look good! This engine had an old school throttle kicker for antilag so that was also eliminated and updated.

The easiest way to make everything fit nicely is to cut the manifold balance tube and reweld it on a shallower angle. The standard throttle body holes were welded up and redrilled to suit the 996 Turbo DBW throttle body which also has a larger butterfly. This 3.2 manifold had already been put on a flow bench to equalise the flow through the runners so the whole job was fast and painless. Just the way I like it!

One other upgrade we did while the engine was being rewired is ditch the old coil packs for the twin plug setup and update to coil on plug. These have plenty of spark energy for the amount of boost that this engine will run and clean up the engine bay.

This engine has a date with the engine dyno before it is put back in the car so I can see how efficient the barrel intercoolers are compared to other systems I have tried. We are going to continue of our fuel testing with this engine as well to show what a massive difference the ETS Racing Fuels make to power and throttle response….

Retirement for Old Porsche Cup Cars…

December 17, 2016 by Promotive

Back in the old Porsche Cup days, the early shells were the cars of choice to chop up and turn into race cars. It made sense – they were light and plentiful, and who would want a stylish long nose car when Miami Vice influenced the trends of excess. Everyone wanted a 911 that looked like the outrageous Gemballa Avalanche and Konig Road Runner specials that had tails so big you could land a helicopter on them. Heck, I still want a Scarab and a pet crocodile just like Sonny Crockett…

The dilemma now is what to do when you have a one of those early shell Cup Cars… With the price of the early model cars, particularly like a 1969 E like this one the choice is quite difficult. One option is to rebuild the car back to standard, find the matching number engine and pretend that owning a car that has the power of the average lawn mower actually excites you. Or you could go down this path and build a toy that can be used on the road and on the track…

This build is not cutting any corners at all! Unfortunately the firewall was substantially cut out as was the trend for the old school Porsche Cup Cars. New panels needed to be welded in and I needed to form a new transmission tunnel to suit the stronger G50 gearbox while retaining the standard look. The full cage was cut out and replaced by a beautifully welded bolt in cage to make it road legal again. The car already had MCA shocks which are as good as money could possibly buy, so only the spring rate needed to be adjusted to suit other than replating everything and making sure everything was spotlessly clean.

I have never been a fan of the 993 GT2 look so it was quite a relief to cut the quarters off the old yellow car. They were replaced by rear flares that could be best described as ‘911 ST flares plus a little bit of extra width’. The whole body was taken back to bare metal. Every dint in the body and place in the floorpan where the car was jacked up where it shouldn’t have been, has been repaired. The shell really looks amazing as repainted in Ivory White.

To sum this build up with a few dodgy photos really doesn’t do it justice to the amount of work to get it to this stage…

Motorsports can be so frustrating!

November 9, 2016 by Promotive

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…

Ceramic Coating – bling with function!

November 24, 2015 by Promotive

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

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!

Why I love my engine dyno…

April 7, 2015 by Promotive

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!