Two Guys Rally

The Volvo Chronicles: Solved It!

So this should be the last chapter in the long saga I’ve had in trying to find the missing power in the upper RPM range of my S70. I’ve tried a lot of things, from doing some temporary testing with the downpipe loosened to check for catalytic converter blockage to replacing the compressor bypass valve diaphragm.

In my last post, I mentioned the turbo control valve (TCV) as the next part that I was replacing. For those of you who don’t know, the TCV is a little solenoid that controls the opening of the wastegate. In the case of the Volvo, there is no pressure sensor after the turbo (MAP sensor), and the boost pressure is calculated using the airflow values from the MAF sensor and the engine rotation speed. I believe the target is 0.7 bar, or 10.2 psi.

In order to keep the boost in check, the ECU uses the TCV to force air from the compressor housing into the wastegate actuator, opening up the wastegate. This allows air to bypass the turbine wheel, reducing the rotational speed, and dropping boost. I found a nice diagram of the turbo and associated parts:

The TCV is circled in red. As you can see from the hoses, the TCV simply allows or blocks air from going to the wastegate actuator. Since the air is coming from the turbo, it can be a little dirty, some excess oil from the crankcase ventilation and the turbo itself. This contaminates the solenoid over time, causing it to respond slowly, and sometimes outright fail.

So, if the TCV gets contaminated or fails, it won’t be able to maintain the proper boost levels, causing the performance of the engine to drop. One option is to do away with the TCV all together and put in a manual boost controller, which is basically a spring loaded valve that opens to open the wastegate at a certain pressure. Although you can use this to bypass the ECU’s control of the boost pressure, and potentially increase the boost higher than stock, you run the risk of overboosting and causing damage.

Anyway, I replaced the TCV, and everything is good. Power is strong up until I reach redline, whereas before it was falling flat past around 5,000 rpm. So at last, my search is complete, for now.

One interesting side note is that there used to be an interesting hesitation around 1,500 rpm in 1st gear, when pulling away from a stop. This no longer happens. I cannot figure out why this is, since the turbo is making no boost at this point. I’m certainly not complaining, since I love smoothness and predictible power response, however, perhaps one of you has an idea why this is happening?

Here is a Video

Why a video today? We’re swamped in work that has nothing to do with TwoGuysRally :(. So to keep you entertained and amazed, heres a video of Richard Burns flying in Finland:

Link for you RSS peeps.

Rally America Rules and Diesels

Rally America gives you a slight advantage if you chose to run a diesel in their Production classes. In order to equalize different cars in a class displacement limits are given, but it is not always the engine’s actual displacement (unless you’re running a 2WD NA car). They calculate it by providing multipliers for certain aspects of a car. A car with AWD is given a 1.3 multiplier, so if you were running a 1999cc NA AWD car your recalulated displacement would be ~2599cc. 

So the multipliers (as of 10/25/08) are:

• Rotary - 1.8
• Forced Induction - 1.7
• AWD - 1.3
• Single Cam / Pushrod - 0.8
• Diesel - 0.8 

So Diesel’s get a displacement advantage. So a 2000cc AWD NA diesel car would have about the same adjusted displacement as a 2000cc FWD NA gasoline car (80cc adjusted difference). You may or may not know that diesels tend to make more torque and consume less than their gasoline counterparts. So I wonder why they get the advantage in the rules.

This makes me wonder how a TDI would do in the rally world, especially in the open class (no displacement advantage given). Although I wonder how and if you could do an Anti-Lag system…hrmmm. While I’m thinking take a listen to the most famous diesel race car: Link for you RSS peeps.

 

Useful Link: WRC TV

The WRC has eagerly embraced the internet as a content distribution device. If you have Windows Media Player (sigh) you can watch tons and tons of videos and waste tons of time over at WRC TV. The downside is it used to crash Firefox often but Chrome handles it like a champ. 

If you don’t want to watch things in WMP then head over to the WRC’s YouTube channel. They have neat videos like this:

Link for you RSS peeps.

Rally America’s Super Production Class

So, what do you do when you don’t have a rally car and are saving up to buy/build one? Read the rules of leagues you want to compete in of course! How else can you correctly dream about building your car?

Anyhoo, after reading lots of rules regarding competing in Rally America I stumbled onto one of the most awesome classes (next to open): Super Production. First let me explain Production classes:

Production Classes
Basically they are the classes that are closest to stock from the factory. Buy, add a cage/seats and race. You are only allowed to modify certain things, and the car’s settings will be similar if not the same to the factory (gear/differential ratios, etc…). For example, the brakes on most race cars are heavily modified, but in the Production and Production GT classes you cannot make the friction surface in the brakes any larger than stock. You can add beefier suspension as long as it uses the original mounting points on the frame of the car and as long as it works the same way the stock car’s suspension worked (ie Leaf or Hydraulic or Torsion).

The interior goes only slightly modified. You have to keep the front interior the same (dashboard and a-pillar) but you can get rid of carpeting and sound proofing. Of course seats are replaced with one piece racing seats and rollcages are added.

The engine can be barely touched at all. All routings have to be the same as factory and even the cooling devices have to be OEM sized. The only modifications allowed are usually electrical in nature, related to ECUs and tuning. While you cannot replace the factory ECU you can reprogram it.

There are also weight minimums for the Production and Production GT classes. For the production class it is 1.05 lbs per adjusted cc of displacement. So, if you have a 2 liter natrually aspirated engine in a FWD car, your minimum weight is 2100lbs. 

So how is super production any different?

Super Production
It borrows a lot from the other production classes, but is far less restricted (hence the super). Plenty more things are modifiable. It is especially the cheaper parts that you’re allowed to go crazy with, like the brakes. They only restrict you in choosing cast iron rotors only (aluminum hats optional) and you can have no more than 4 pots/brake. Other than that you can have the largest/smallest friction surface you can fit (while also being street legal!!). 

Weight minimums are thrown out the window, except for WRXs and EVOs. So the cars can take turns at higher speeds (less intertia) and accelerate way quicker than their Production class counterparts. 

The engines of Super Production cars, hopefully, out produce the engines of Production GT cars. Turbocharged/Supercharged cars in Production GT have a 32mm diameter inlet restrictor on the intake, while Super Production cars have a much larger 34mm. While it may not sound like a ton, 13% increase in intake size means 13% more air available to the engine (all things equal), hopefully that means 13% more engine power. 

Super Production cars are also allowed to play with cooling devices’ positions and their hoses. This might make for quicker responding cars and cars that won’t break from overheating. But what really sets Super Production apart is the fact they are allowed to use whatever ECU they so desire. Aftermarket ECUs provide much more flexibility in how to tune the engine.

I’m eager to see what competitors start showing up in the Super Production class as they’re going to be quicker than their production/production gt counterparts. I’d be eager to see what cars end up winning the Super Production class (WRXs and EVOs I imagine). I’ll keep watching to see how this cheaper than open class class evolves.

Eagerly Awaiting Snow

Snow is, by far, my favorite type of weather. I just love it so much. With snow coming soon (it is supposed to flurry this week) I figured I would start watching snowboarding videos and then I came across a video I had seen before: Ken Block Driving With Snowboarders. You should watch it and become just as excited about the upcoming winter as I am.

Link for you RSS peeps. Oh how I cannot wait until it snows for both driving and snowboarding in. 

Rally America 08 Season is OVER

Rally America’s 2008 season ended this weeked with their final event of the year: Rally Michigan (aka LSPR). Travis pastrana had already locked in the overall championship win but decided to get a podium finish anyway (~2 minutes behind first). Travis’ well known teammate, Ken Block, ended up winning the Rally to keep Sarasin out of 2nd overall. Kyle Sarasin didn’t give up on second easily and ended up with a 2nd place finish at the Rally (~1 minute behind Ken).

Kyle Sarasin did, however, end up 3rd in the overall championship this year. I would say this has been a good year for this up and coming rallyer. Did you know he is still a teenager and barely a legal adult? There is a lot more that is going to come out of this racer in the future (or so I hope his budget permits). He’ll be someone to watch, for sure.

I guess the competition pushed ACP into DNFing this weekend. He still ended up 4th in the championship but a DNF is a demoralizing way to end a season.  You should go watch ACP’s videos and make him keep racing.

Either way, it was a neat end to a season and I hope to see some more exciting races next year. Sno*Drift here we come!

A Side Effect of Rally Being Popular

France. Well known for the “finer things”, wine, cheese, gourmet food, long life spans with ‘terrible’ diets, etc… But an oh so famous French car company Renault has just made me jealous of Europeans. They’ve started selling a ready to race, from factory, Rally car that includes an Electro-hydraulic(maybe mechanical) sequential transmission: The Clio Renault Sport R3. 

This machine comes in two kits (really kits). One for 32,600 Euros and one for 53,000 Euros (only sold in Europe ~ $44,000 - $70,000).  The latter of which has parts that are designed to handle gravel stages. Oh how I wish Renault would sell at least a few of these in the US. I think they would dominate FWD Rally in the country (given a decent driver). 

I wonder if they would be legal in Rally America? Hrmm…

The Volvo Chronicles: CBV Diaphragm II

It seems like all I post about these days is my own car. Hopefully Charles and I will get our hands on a rally car to work on, but for now, the Volvo will have to do as my source of entertainment. Anyways, a long while back, I ordered a CBV diaphragm to replace the old one in my car that I had suspected to be worn out and torn, allowing boost pressure to leak out.

I finally got around to replacing it last weekend. The old diaphragm was in much better condition than I thought it would be, however, the rubber was definitely worn. The sealing lip that gets compressed against the turbo was leaking, creating the huge mess on the turbo:

(click for larger)

However, there was something very significantly wrong. The hose that leads to CBV that supplies pressure or vacuum depending on throttle position had torn almost all the way off. Unfortunately, I missed this when replacing the vacuum hoses, so a new hose got put on with the new diaphragm.

After driving it for a week, there is a pretty noticable difference in power in the mid rpm range and top rpm range, though more in the mid than the top, which is opposite of what I expected. The turbo flows more air at higher rpm, so perhaps the leak, which would remain constant due to constant pressure, became less and less noticeable.

So in the end, the top rpm range still isn’t making the power it should, and I need to figure it out still. I have a new turbo control valve (TCV) that controls the wastegate actuation on the way, and I’ll try that out too. If the stock unit is fine, the new TCV has improved response over the OEM unit. At the very least, it should be able to control boost more precisely.

However, an important lesson can be learned from all this: Turbochargers are complex systems that have many parts to wear out and cause poor functionality. In a rally car, these components wear quickly due to the demanding conditions, so make sure you stay on top of the little small things in your car!

WRC Corsica 2008: Results

Rally France (Corsica) was this weekend. Results were not too surprising (with one exception). Sebastian Loeb continued his domination with a podium finish over the weekend. However his teammate Sordo decided to ruin Citroen’s chances of yet another 1-2 finish by crashing. Sordo took a corner not so correctly and ended up in a rock wall. Taking Sordo’s place was Mikko Hirvonen giving him much needed points in the race for the championship (14 points off of Loeb overall). However his second place was a team effort as Francois Duval checked into the time control early, on purpose, in order to take a 2 minute penalty to push Hirvonen into 2nd, while taking 3rd for himself. 

Petter Solberg, one of my favorite drivers, placed fifth in this event. He earned himself some much needed points to pull in Latvala for 5th overall (2 point difference). Here is a video of some of the highlights (wow they pump these videos out quick): 

Link for you RSS peeps.