I haven't raced in chump car and can't comment on the specific rules of that series, but typically the common thread in other series - you can't alter the boost system without penalty, or the max boost level is set by rule, or there is a hp/wt formula. Any of the ideas or methods listed above would not be legal in the series I mentioned, without penalizing or progressing the car to another class. So I would guess much of this is cheating, some just might be easier to conceal than others (?).

If it matters, you can buy zinc dichromate plated 3.0 bar FPR from bosch, no need to spray paint a black one. But...

The KLR overboost fault code is really not an issue, you likely won't have that kick in. The DME overboost fuel cut is the problem with any slight increase in boost on the K26/6 cars. Putting a bleed in the KLR boost line or small pressure regulator to limit the boost the KLR sees won't help or eliminate the overall issues here.

Another point to make, trying to trick the DME into thinking there is less air going to the engine than actual is not a good path to take. By increasing fuel delivery, you may be able to crudely tune it to work at wide open throttle positions (full load maps), but the car is going to run like **** at every other throttle position.

The factory Turbo Cup cars running higher boost in the SCCA Escort series were prone to lose head gaskets during the endurance races. This was with factory and PMNA support. In the end, well over 100 octane fuel was needed to keep the cars from detonation with high boost, high heat/heat soaked conditions during endurance races. So if running higher than stock boost, are you legally able and willing (budget) to run 100+ oct. race gas for the duration of a 24 hour race? Figure about 6 mpg at $8/gal.

 

Remember that the Escort series was before Porsche put out tech-bulletin to increase head-gasket torque by about +15%. Perhaps the bulletin was due to those very experiences in Escort racing.

 

Are you refering to the change from a torque spec to the torqe-angle method in the head tighting sequence? First document I have with that change is dated '91, though maybe issued earlier. Lot of reasons for using a torque angle method vs a torque value, and most have to do with reducing variation in clamping force due to unequal friction from one nut to the next. Lots of threads already on rennlist regarding studs, head gaskets, and torquing procedures.

But if you run high boost w/o proper fuel/ignition curves and w/o proper octane fuel on the race track for any extended period, it doesn't matter what torque spec you use on the head, what head studs, O-rings, head gasket material, other - you will burn or damage something, whether it's the head gasket, exhaust valves, spark plugs, pistons, or rings.

There is much more to the history of the race series and the car development, but to oversimplify for the sake of this thread - the cars in the Escort series attempted to maximize fuel economy to reduce pits stops over the duration of 6, 12, and 24hr races when competing against the Corvettes (which actually had an advantage in fuel stops over the 951s). Running rich obviously hurts fuel economy. More so than head torque specs, the lesson learned was that the combination of being on the lean side of the curve and lower octane is a big risk, and often ends in something failing. And the head gaskets are usually one of the first victims. When the tuning was altered and well over 100 octance used (factory recommended 104, teams ended up using 108+), the cars were relatively reliable (but certainly fuel consumption was a competitive disadvantage when going richer with the 3.0 bar FPR in '87).

Which is also a consideration for the OP - additional fuel stops over the course of a 24 hr race when running higher boost and using more fuel (+6 to 9%).

A few pics from 3 different/separate engines, showing damage that occurred on track due to less than ideal tuning conditions.

 

what is the target A:F for a long stint? assuming a reasonable timing curve?