how much boost can you run on the street in an FD safely with 91 octane pump and Protek-R (or any other synthetic pre-mix) knowing that you have a good fuel system to boot??

i know this is a vague question, and difficult to have an exact answer, but i just want a ballpark figure.

 

If your tuned correct, and this is a big IF, I would say anything over 16lbs to be on the safe side. Some run as much as 18lbs on the street. Its all on your tuning and your motor.

 

I agree that the tuning is very important. I run about 17 PSI on the street with 93. I used to get to 19-20 PSI before I reprogrammed my boost controller. Nothing got hurt, but I'd rather stick with 17. The guy who helped me with my tuning said to use 16-17 PSI as a limit.

 

So I should probably turn my boost down from 22psi? Or maybe just upgrade to 94 instead of 87???

 

i hope you are joking.

other than that...thanks guys!

 

My brother ran 25psi max boost 24/7 on 93 pump gas. He never ran into any problems, except for head gasket but that wasnt because of boost.
Jeff

 

Well yeah, some boingers are more boost-resistant than others... Ford had so much trust in how beefy the 2.3l was, for example, that on the XR4Ti only used the wastegate to regulate boost only up to a certain RPM, then after that the computer just shut the wastegate and let boost climb as high as it wanted... (redline on the boost gauge was 18psi and I've seen those cars bury the needle )

OTOH my Isuzu would blow its head gasket at anything over 7psi. Just like that. Boost goes past seven, "plink" and it starts overheating.

 

The FD has a higher Cr than the TII, and also runs more boost, its being overfueled though from the factory as compared to some other cars, the the turbos were picked to run at the factory boost levels, an intercooler upgrade would be a good step if you chose to run bigger boost with the stock turbo's this holds true for the FD and the TII, I would say anything above 14 psi is playing with fire, but I do not have an FD, I have a TII, the boost comes on alot differently between the two cars, being that the FD boost comes in alot lower than the TII, the chances of detonation at lower engine speeds, I would say is greater in the FD than the TII, if you were lugging the motor in high gear and started to hit 8 psi of boost an low rpm's but highload, the chances of detoantion are alot greater than 14 psi at high rpms, given that you had enough fuel capacity at both.. The question you might want to ask some of the other FD owner is what RPM and boost were they at when the blew thier motors.. Most guys I have listened to that blew thier motors say it was at highway speeds, just bombing along at the speed limit in 5th gear, which would mean, lower rpm's, higher engine loads.. As the engine rpm increase, chamber filling gets less and less, which takes away the chances of detonation, and allows more boost to be run at the higher engine speeds, effective CR is dependenet on chamber filling efficiency, the higher the engine speeds the lower the filling efficiecy, is it possible to control the boost on the FD to make the the first turbo retain its stock boost characteristics, but shift the second turbo's maximum boost up the scale of rpm?

Blowing a head gasket though is not a sure sign of detonation, neither is it a sign that better fuel needs to be used, the cause of head gasket failure from one engine to another is more a function of head clamping, some blocks only use 3 bolts per cylinder, some use 5, the more the better, a wasted plug electrode,mushroomed piston, broken rings or ring lands is a more likely sign that better fuel is needed, in a piston engine anyway.
Several of the big rotary houses like Racing beat and what not, say that over certain limit, the rotor housings start to walk around, the side housings warp, and the rotor faces collapse, after a certain point, they all have their own number for maximum boost, some say 16,18,20 or as high as 28 psi. It depends on who you listen to..
In most of the turbocharging and engine books, one can find a graph that illustrates the octane requirement of certain compression ratio engine with a certain amount of boost, if one follows those graphs, it shows the TII engine at being safe at 7 psi of boost with 92 octane, these graphs do not however have the rotary in mind, nor do they show the spark lead, intercooler outlet temps, turbo efficiceny or altitude correction, consider these graphs as the absolute 'safest' guideline, and you can push start pushing the envelope from the points on the graph by taking more precautions with it, such as plug heat range, better intercooling, more fuel, less spark lead, and attention to motor asssembly when trying to avoid detonation.
When I look at the over fueling that is needed when running big boost on a rotary, it makes me think that this is a patch for insufficient intercooling more than anything, but there is a limit to how big an intercooler to get, and you will always be limited to the lowest ambien temperature the car is run in, unless you have some sort of mechanical stand alone intercooling device, like a refrigeration system onboard..Over fueling though does have a limit, once carbon builds up on a rotor face, it increase the chance of hot spots or glowing embers on the rotor face, and increases the efffective compression ratio of the engine, which makes the engine more prone to detonation.
I would think if really big boost was your perogative from the beginning, you should take all the steps neccesary to stay away from having to overfuel and always run 100 octane race gas, start with the coldest plug possible, run the least amount of timing you can get away with, radius any sharp edges or sharp protrusions on the rotorface combustion pocket, biuld the motor for the boost, maybe some extra doweling and better apex seals, get the best intercooler you can get, and pick the turbo for the boost you want to run, so its at its peak efficiency at the boost level you want..
Sorry for the "war and peace" diatribe, I just couldn't stop typing..Max