I race in SCCA ITB and am building up another engine. d15b2, block decked .010, head milled .030, bored .020. Cold air intake and headers for better breathing. Question..using the stock cam (rules) would I gain anything by advancing or retarding the cam timing? If so, advance or retard and how much? Another question..how about the computer..where do I send it to have it reprogrammed? I don't want just a timing advance and richer mixture by adding a $70 resistor.
Help me go faster..I run 3rd now to usually a stinkin Volkswagon!!

 

thats a tough question on that ecu and the fact you cant switch to an obd1 ecu can you?

advancing the cam could net some type of return in power but only to be seen on a dyno, i assume you mean at the distributor since you cannot run cam gears.....but you could machine the oem cam gear chuck location to slightly a different location stealth mode..............................

 

Cam timing refering to rotating the gear on the cam shaft? If so, you should double check the rules. I have not read that section in a while but I do not believe you can do that. I think there is some wording which will allow you to return the cam to zero to compensate for decking.

 

no you cannot do that, the method i have listed is one of those modifications that people do that is easily hidden.

 

So you want him to cheat? And now me and couple of thousands of friends know about your stealth mods. Now tec knows what to look for.

 

never said i wanted him to cheat, i dont have to use oem gears in my class, its not like people dont know this, and its not my mod. technically you are using an oem gear, you could do this by being a tooth off as well on a sohc.

its common knowledge

i dont know how you would even know to check something like this, would you really want to risk the impound and paying the cost of the tear down anyway to protest it?

rafaelli is correct with the decking and returning to 0 which is probably how this came about many years ago....

there are a lot of things that are "rules" but are overlooked, for example in ITB you cant use reinforcement for the swaybar but most people do to prevent subframe tearout and potential safety issues. the asr bar should not be legal but its widely used, its not a secret either and not exactly something that is hidden but its tolerated.

 

Sorry misunderstood the term "stealth" .

 

to bad you cant use the a6 cam since its from a pm3 head also.

 

195rv How long have you been racing? You make it sound like that vw is really giving you hell on the track? What part of the track is the vw faster? Maybe you can outcorner him or her. I am suspecting that in the class you are running that the margin of victory is very narrow, which makes for fun close racing. In these situatuions experience trumps all.

 

If the cars are equal in HP and the driver can't overcome his "arch nemesis"...
Then im inclined to belive the above statement is true and the OP needs to work more on his race craft, and find out what the vw driver is doing right vs you not being able to stay on pace with the vw.
Horsepower does not equate to beating another car, its the drivers abilities to outrun everything on track no matter what he has under the hood.
I have seen many a great driver take an almost bone stock car and spank higher HP'd cars.
Go back and review a post from Matt Bell not too long ago.
He was driving a mild tuned car vs his opponent who had a High HP boosted car.
Their TA times were fractions off.
Sooo as it has been proven... High HP doesnt always make you faster.
The only place more hp really matters is on a drag strip.

 

You can advance the timing via the distributor, but like stated before the only way it can be done scientifically is on the dyno. When advancing ignition timing you usually gain up top but maybe loose a little mid range. It all depends what the rest of the setup on the engine works best with so a general (run at 14* advance for a little more stink) statement wont always be true.

Another trick to make your engine a little more efficient is clocking your spark plugs. Since you will already have the head off you can buy spark plug shims to adjust the position of the electrode when the plug is torqued to a given spec. If you do this I recommend torquing each plug a few times to seat the crush washer, then start playing with shims to aim the spark towards the intake ports.

If youre getting left behind on straights you can also try playing with your toe settings. Depending how the car feels you can take out some toe to run closer to 0 for less rolling resistance, and use another aspect of the suspension to gain back the feel you may loose whether it be spring rate, tire pressure, or adjustable sway bars.

Also, depending what your tire temps are now you can try running higher pressures again for less rolling resistance. Even if your temps are less than optimal with a higher pressure, the gain on the straights may outweigh any loss in tire usage in corners.

You can also streamline the front of your car by blocking off unnecessary vents in the bumper causing pockets of turbulent air.

Rebuilding your front calipers with new square cut seals and dust boots can also help keep the pads just an extra few thousandths away from the rotors for less drag. I usually like to do this at least twice a season because the abuse of racing environment really puts punishment on those parts.

 

Every race track has several drag strips. They are the straight bits between the corners, where higher HP will definitely make you faster.

 

Damn Claude! You are so technically correct!

It is SO hard not to want More horsepower. My kaa is on jackstands and I want more power.

Scott, who knows that having less means that YOU have to make up for the difference, and that can be a mighty good thing...

 

ITB rules do not prohibit degreeing the camshaft, nor do they prohibit the compression ratio I now will have. I must use the stock camshaft, which I am. The stock computer can now be reprogrammed (new this year). I can easily catch and stay with most anybody in the turns, but watching him pull away in the straights is getting old. I am not trying to cheat, nor am I now cheating..just playing by the rules.

 

Well is your build a 10/10ths build?

 

Can you point out the section that allows you to do that?

 

There is no mention of degreeing one way or the other. The rules simply do not allow a different camshaft than the stock one, therefore adjustments are allowed. You must think like a lawyer. I'm not sure degreeing the stock cam would add anything anyway..hence the question of how much for optimum performance. The engine and car will remain absolutely legal in every way. I suspect bringing up the compression to allowed limits and re-programming the ecu (allowed this year) will add some additional performance.

 

And to answer dirty19..I was class champion some years ago and well understand the driver thing. I think my partner and I hold our own quite well for driving an absolutely stock CRX with well over 200K on the car. (the valve cover has never been off the engine!)

 

Also to dirty19..Straight away speed begins with the speed you can carry off the last corner..fast in and fast out is the straight away speed. Apex the corner while carrying good speed, without binding the car..fast.

 

I think the reason he wanted you to point him to the rule that says you can because the rules is... If it doesn't say you CAN, then you CANNOT. Period.

Nevermind.. I found the rule that says cam timing can't be ANYTHING other than factory specifications.

 

Our machine work is within those specs, and the offset key is the answer I'm attempting to determine. Which way, advance or retard, since the key will allow either direction. We do not have access to a dyno as we are poor people and live in small town America. We are racing on a budget as are most people. We want this engine to be reliable and long lived. Hope someone knows this answer, without speculation. Thanks for the effort.

 

I know the answer. I'm using bold and caps as to be clear, not to be a dick.

Shaving the head, decking the block and whatnot makes the cam pulley physically closer to the crank pulley and thus effectively retarding your cam. The ONLY 2 options you have that are legal... ONLY 2 OPTIONS THAT ARE LEGAL: leave it or key it back to stock. If you leave it you will only be retarded on the cam by 1-2 degrees, very minor, very unnoticeable. If you key it and advance it past stock by ANY MEASURE, you have broken the rules and would be CHEATING.

You might as well leave it for 2 reasons. The camshaft timing will only be tardy by a degree or 2 which makes almost no difference. Also, on SOHC's, in my experience, when you tard the cam a couple degrees it shifts the powerband toward the top end. I have found this beneficial to me so I have not returned my cam back to stock. I like my engine to pull right up until the computer tells it to stop revving.

 

Exiting the corner faster makes you faster.

 

There are no provisions to allow modification to the cam gear (other than to change it to metal). Since the cam gear/cam key is machined into the gear, I would summize that you cannot modify the key since it is one in the same as modifing the gear.

I suppose you could modify the crank/crank pulley key to adjust the cam timing back to OE since it is a stand alone key and the same non modification applies. However, that thing already has a very small cross section so I am not sure you would want to.