77k miles, 8k of those with the Pettit Kit. No blown motor.....yet.

I must not be trying hard enough. I'm gonna have to do something about that this year.

 

Yeah. I hadn't even hit full boost in my first 8k miles.
I'm closing in on 40k miles of boost.

 

I run my Pettit with a Borla Catback; 2K miles, no problems so far. Smooth as silk, howls like a banshee at 8 grand. I don't drive mine like I stole it or thrash the crap out of it, but it make a nice ride up the local mountain passes then purrs through city traffic with n'er a glitch.

 

We're all ears, Jeff.

 

Yeah!!.....what else will I need to make it reliable?

 

fixed.

 

Pretty much all the same stuff for every FI installation - bigger injectors, bigger rad, new fuel pump/filter assembly, engine bay ducting, etc.

 

Is this a "need" or a "bling"? And does it depend on how you drive? My Pettit system is smooth as an electic motor right now. I don't drive it like I stole it - just drive it. Use the boost when I need it.

I've modded EFI motors for years now and never had to up the injectors as long as my ECU had a good map. Heat from the extra power, that's another story, but depends on how how hard you drive. Is "reliability" relative to how hard the car is thrashed?

 

Then you haven't been asking much from the motor.
The factory injectors on the 6-port are good for just about 300 - 330 crank HP. If that is all you want (about 260 - 270 at the wheels), then you are a member of a fairly lonely club.

 

You must mean the "common sense" club. I have to desire to make an idiot of myself by grenading an overboosted engine trying to race a V8 'stang and then trying to pass it off as an accomplishment in print.

While I'm sure everyone here appreciates your experience by attrition (I certainly do: "40,000 boosted miles in 3 motors), since the conversation centers around "reliability" with the Pettit kit, I fail to see where fitting larger injectors to a motor in a reasonable state of tune is going to improve "reliability". However, it's dead certain you'll have some smartass remark to explain it. I'm looking forward to it personally. It would be stunningly refreshing to hear you dispense useful information to everyone here without whipping out your dick.

You must have glossed right over my previous statements about "live-at-home momma's boys living vicariously through their avatars."

 

I laugh when I read stuff like this on the forum. He's been honest about his rx-8 experience, both the good and the bad. You fault him for telling you why something isn't ideal, and then you fault him for telling you the truth on why he blew an engine. He could have said anything and no one would be the wiser.


I'm now running similar numbers to his, and just about every other turbo kit available for the rx-8 does well over 300. Yet all we hear about is how there were so many greddy turbos blowing engines from way back in the day. Do you recall that back then most greddy kits barely made 240 whp? It isn't the horse power number or PSI that determine how long your engine will last when talking about 40k worth of FI usage at our power levels. It depends on a number of factors, with tuning at the top of that list.

I won't make claims to why you're doing this, but if you own this kit and you're fine with having less acceleration than a greddy kit with 9 psi, more power to you. However don't lash out because you are trying to avoid buyer's remorse by ignoring the facts and making personal insults at others.

 

peace

While what MM said is not ideal, it's also not true. All the flashed Pettit FI'ed MT 8s(most of them, now) are at or over 300rwhp on stock fuel injectors at ~8psi.

BTW, your car looked pretty nice, but hurry up and get that hood painted.

 

I love reading this stuff!!I suggest you trip over to the RX7 club forum and check out the 752RWHP Street Car(3rd Gen,Time Slips and Dyno).I suppose you guys will eventually get out of the sandbox!!

 

I wish I could, but having just bought so much crap recently (ignition system, clutch, flywheel, turbo, exhaust, etc) I am trying to behave like a sensible adult instead of a kid who has a pocket of quarters in an arcade.

 

Then how, good sir, are the flashed Pettit kits making 300+WHP with stock injectors??

 

Even still, it's probably still good advice to upgrade the injector and ignition systems, although I wouldn't call it a necessity to break 300whp.

If anyone's interested in seeing the Pettit kit in action, there will be two equipped RX-8's autocrossing at BCC in Palm Bay next month.

 

Yeah, I must have. Sorry. I don't really put much effort into reading stuff you type.
At least I haven't yet put you on ignore like poor Bastage.

I dunno. Haven't seen an actual dyno of Pettit user yet.

1 290cc injector. 2 380cc injectors. 2100cc of fuel for the whole motor.
85% maximum duty cycle. BSFC of .55.
Crankshaft power potential = 309 HP.
A BSFC of .55 is pretty optimistic for a rotary. But, whoever might understand the math in this probably already knows that.

 

Really? Damn, I missed it. Well, thank him for me.
I guess that's the bad part about the ignore list.

 

why only 85% MM ?

 

Injectors heat up pretty quickly above 85% and their actual open duration becomes unstable.
There are people that will tune for 100% duty cycle. It is a really bad idea.
I consider 90% too high.
Fuel rail pressures become unstable from one injector to the next as well.

 

The OE calibration for the RX-8's injectors never take them over 80%.
The primaries peak at 80% right around 5500 RPM and actually go down from there to 55%.
The secondaries climb to 80% by redline.
The P2s don't even turn on until 6250 and never see more than 35%.

My own tuning efforts have always been complicated by this restriction. I have had successive tuning iterations place my secondaries near 100% and I've had to continually look to push the load onto the other injectors to avoid this because the A/Fs are unpredictable if the secondaries go above 85%.

 

Perhaps Petit get away with more because the hp curve is so linear ? IE they only hit 300hp for a brief moment at the top of the curve .

 

With 2 rotors?please show me.

My only point was to take a shot at a member of the MM Sychophants Club(of which you are also a card carrying member!)

Leave the supercharger guys alone why don't ye---they are happy with their choice perhaps.

 

Charles, if I upgraded my injectors, would I need to have a different tune or would the duty cycles just stay more consistant?

 

Yeah, Charles, I agree to a point; however, you and I both know that more power=more heat=more stress=more breakage. For myself, 300 on the ground (or even 20HP on either side of it) is a lot to handle on public roads with the DSC off in the tight stuff I like to unspool in. I also know the Renesis has it's limits based on apex seal and eccentric shaft bearing life. However: I've found that not breaking my toys so as to be able to enjoy them more to be greatly more rewarding than running them to the ragged engine and then loosing them to a costly rebuild.

My comments to Jeff stand; however, I do recognize his willingness to finance the research to see just how far this package can be pushed, not to mention the depth of his experience. Yes, he's quite a tuner, or parts changer, not sure which, but I'll be the first to admit he's been places I sure as hell don't want to go. I'm just not going to swallow the sarcasm along with it.

I may blow an engine, yes, but it won't be because I wanted to twist it past its tolerance, and not because I wanted to be a street racer against a small block V-8. The Fast and the Furry-Assed was just a movie. Just because I have 300-ish hp doesn't mean I feel like I need to use it; I just don't have to rip it so hard to get the 200 or so I use most of the time. I don't consider myself 'lonely' by any stretch. I like to think of it as smart.

By the way Jeff, in all seriousness, thanks for the thought process on the injectors. I'll run it by some of "my people".