Boost questions???
 

I just got a vert Rx7 and am in the process of swapping a TII jspec motor and tranny. My concern is I know they run stock around 8lbs of boost right?? but how much boost can I run w/o problems. I plan on getting the FMIC, BOV, bigger injectors, hi perf fuel pump, and of course the turbo back exhaust ,BTW which I'm looking for :evilgrin: but how much boost is it safe to run for daily driving and/or racing? I don't have a ton of money but I do plan on getting a street port job next year (poor man lottery; income tax)

Any addl' info will help out

You could maybe go to 9 psi boost, but lower is better. You know how boost tears up piston engines if its too high, right? Well it F**KS up rotaries hard. My suggestion would be to keep the stock boost, but thats just me..

Does anyone else have any input???

It really depends on your setup, what turbo, etc. With stock turbo, probably around 12-14lbs max. Youll want to dyno tune the car and see what your A/F ratios are at and tune it for a certain boost level to be safe.

with bigger injectors, fuel pump, and FMIC. the stock turbo will be your restriction. around 12-14psi. you will want to get a way to tune it. like a apexi S-afc. and have the tuneing done by a pro with a wide band o2. if you are running up around 12+ psi you might want to retard the CAS a couple degrees too.

about 12 psi sounds just about save with a good tune up, thats what I am running and no problems thank god

Thank for the input guys... what size turbo would you recommend with it... I think I would stay around 8 for daily driving and bump it up to 10 for racing...

BNR Stage III or II. That is what I am planning on at least. It keeps your stock turbo core and changes it to a T04 hotside I think, anyway it bolts right up and you can get upwards of 300+ out of the Stage III or Stage IV with the right mods :).
http://www.rx7store.net/subcatmfgpro...220&1=364&2=-1
That is my suggestion! Have a good one! Good luck!

--Fritz

ive been running 10lbs with no prob with my greddy profec. also port your wastegate. it helps. injectors is a nice touch 2. s-afc all the way. ive got a 88 t2 motor, upgraded fuel inj. profec A EBC w/ nothing done to the motor so far cept down pipe, FMIC. motor has 89,xxx mi, still kicking, but waiting for her rebuild. this summer.

yah if u get up to 12+ psi on a stock turbo youll wanna port the wastegate. do it anyway :)

also get a FCD (fuel cut defensor) if the boost pressure sensor sees any boost running higher than 8.7PSI(memory is hazy, correct me if im wrong) it will cut fuel off to the rear rotor as an overboost safety precaution, Since the fuel doesnt get cut Instantly and lets some fuel in to be burned, this causes a super lean condition which can cause the rear rotor to detonate. Id suggest investing in an FCD, Racing beat has nice units from what ive heard, Im running an HKS unit and it seems to be working fine for me despite all the bad things ive read about them. -alex

awesome input thanks everyone..

I have been running about 20psi on my stocker. I just got a BNR stage 3 and will probably run the same. The differance in HP is pretty noticable at 20 psi than 12. I am currently running a Racing Beat turbo back exhaust, FCD, Rotary Performance fuel pump, 720cc secondaries, SAFC, 3" Banzai Racing TID, light weight steel flywheel, Center Force stage 2 clutch, 10mm Magnecore wires, and a Greddy BOV. So far I have had no problems and have ran this for a year. I use 20/50 mobile oil and run 92 octane. I have my SAFC set so it is 2 bars in the rich area on my A/F gauge under load and runs slightly in stoich when just cruising. Anyway I have found a lot of DSM guys are running 20+ psi so I did it just to keep up with them. I have a FMIC, and still need to buy 2 850cc injectors before I run the BNR once I get those 850 injectors I will be running 20 psi on that to. Just make sure you let your car cool good before shutting it down. Hey this is worked for me so far I am not saying its "safe" but I am saying I have not had a problem with it in the last year.

holy sh*@ that is a lot of boost!! I don't have the balls to run that much boost on my stock engine... at least not yet... I'm still learing as I go... how much hp to the ground? time slips? mine is going to be a daily driver is yours?

holy sh*@ that is a lot of boost!! I don't have the balls to run that much boost on my stock engine... at least not yet... I'm still learing as I go... how much hp to the ground? time slips? mine is going to be a daily driver is yours?

holy sh*@ that is a lot of boost!! I don't have the balls to run that much boost on my stock engine... at least not yet... I'm still learing as I go... how much hp to the ground? time slips? mine is going to be a daily driver is yours?

Sorry I dont have any time slips, or dyno. However I know it pulls a lot harder at 20psi, than it did at 12. I have a SAFC and 720cc secondarie injectors. So that helps maintain a good mixture. I ran 20psi before I got the SAFC and 720s and would see the A/F gauge go blank cuz it was so lean under that level of boost between 5-7000 RPM. I then decided to make sure it gets the fuel it needs. I have FMIC I will run with 2.5" piping when I run the BNR Stage3. I will run that at 20psi to. I am in the process of getting some 890cc injectors to run in the secondaries and move the 720s to the primaries. Mine is not a "daily driver" I rarely drive it to work, and a lot on the weekends. I live in ND so it sits all winter in the garage. So its more of a toy for me than anything else.

I always thought that 20 PSI was way out of the efficiency range of hte stock turbos. Off the top of my head, i think about 14 or so is the max for good efficiency.

Well I do not know what you consider efficent..? But I can tell you from experience that 20psi on the stocker is a lot better than 14 as far as power. What do you mean by efficent your not getting the HP per pound of boost at 20 as you are at 14...? Anyway crank it to 20 if you have the fuel and tell me that 14 feels better than 20. I hear the efficency theory a lot. I used to think it was taboo to run over 14, and one day I cranked it up. After feeling the power 20 delivered there was no going back. So I have run that for about a year now. So far so good.