pwwatkins

93 octane
17.5 psi (over boosted to 21 psi this winter a few times)No A/I
500r turbo
stock port
I think around 25,000 on motor, with 7000 while single
Banzai Racing tuned

TK7

iTrader: (6)

not that it matters, but what would a "stock"(apex) motor be able to physically handle? if there was no detonation present.

and i mean, all things aside.......everything necessary to pump whatever boost in.

fendamonky

iTrader: (6)

^ The motor is not the limiting factor. The turbo, gas, fuel system and cooling capabilities are the limiting factors.

More boost = More fuel required and more heat produced.
More horsepower = More boost.
More money = More horsepower.

The "stock" engine is not the variable when the question of more boost is brought up, all the support mods are the variables... Please correct me if I am wrong (seriously, if I have/am passing bad gouge I would appreciate being corrected)

RX7 RAGE

iTrader: (22)

13 psi on 91 octane here

casio

due to the title, i'm not sure what gurus will be stopping through, but i know high power engine builders take certain precautions when building motors beyond just good tuning. 2-piece e-shafts and adding a dowel pin came to mind, but i'm completely ignorant to the purposes of the 2-piece e-shaft (aside from flexing), but the dowel pin supposedly is used as a security measure in a weak spot in the engine (though the one i'm thinking of was in an FC motor; the FD may have a dowel already in this position).

i've been out of the scene awhile due to moving to the city a few years ago, but have recently been looking into RX7s again and the issue of "weak points in the motor" has been something i've wanted to research. you can't just throw 1000hp at a 13B and expect good tuning to keep it together, but i'd like to find out specifically why (i'm sure there's a thread; time to search some more).

fendamonky

iTrader: (6)

Honestly, I think 1000hp is a little bit of a stretch for a 13B, especially in stock form. Anybody who is serious about building their engine for anything over, say 400whp, will invariably alter the ports and seals in the process of a rebuild somewhere along the lines. Changing the ports is logical when shooting for high-hp numbers, it just makes sense. More airflow = more power. Though at this point the engine is no longer "stock".

I feel that it is reasonable to say that owners who keep their internals stock will probably *not* be pushing much over 16-20(ish) psi of boost, max. Even then a damn good IC setup and/or A/I is pretty much a requirement. Otherwise, your intake temps will be horribly out of control, and at that point you're playing Russian Roulette (with five bullets) when it comes to controlling pre-detonation.

To be perfectly honest I don't know much about actually building our engines, though it seems that changing ANYTHING inside the engine itself (port jobs, upgraded seals, e-shafts, etc.) would be classified as a deviation from stock, and therefore not really within constraints of the topic of conversation this thread is based on.

Please do not let me dissuade you though, you bring up some interesting points I've never thought of (and know very little about).

casio

sorry, i guess we're over-lapping on terms. when i say stock, i just mean as far as what the engine can hold (power-wise) without modifications to strengthen it. i agree that porting isn't "stock," but it doesn't aid in strengthening a motor. what i'm trying to find is the approximate power limit of a rotary before things start going kaput and what measurements are taken to ensure a high-power engine lasts. i just chimed in because it seemed like people were saying that the only way to break a rotary is improper tuning. that just seemed highly unlikely, but maybe i misunderstood.

btw - i'm having no luck on my search. i've google'd every combination of words i can think of and then wound up at nopistons reading 4-5 year old posts about porting. *!!!*

skir2222

Before...
1. boost? 15psi
2. Octane? 93
3. turbo? T04R
4. Miles on the motor? 32k

After...
1. boost? 10psi currently but tuned to 16psi but cant hook at 16psi so it stays at 10psi till I can get some better tires and suspension.
2. Octane? 93
3. turbo? S366 Borg Worner
4. Miles on the motor? 4k

Hit Redline

iTrader: (2)

Thanks for all the feedback guys it has been a big help. The reason I was asking how much boost you 3rd gen guys run is because I am putting a 3rd gen motor in my fb. Its a jspec motor and I am looking at getting the most power I can but at the same time keeping it reliable. I have been through a couple of S5 turbo motors due to fuel issues and have decided to go with a 3rd gen motor with fuel injection, Haltech, 1600cc secondaries, and custom baffled fuel tank.

I was having a discussion with a friend that you guys were running as much as 17 psi on 93 octane and I got my answer. I also understand that a larger turbo with lower boost will make as much or more power than a smaller turbo at the same psi. Again thanks.

fendamonky

iTrader: (6)

I'm pretty sure you can map to hit 12psi on your primary, than jump to 16 after 4.5k rpms, that's how my pattern goes when I have my boost controller set to 1.1 bar. I'm using a brand new set of BNRs so I know it's NOT my primary being busted. I was a bit at first, but then it clicked in, my tuner is certainly smarter than I am ^_^

FWIW I'm running 17x9.5 on my rears and can still break loose/fishtail (if I try) at about 60mph while pushing 1.1.

Syritis

iTrader: (2)

not so true. with my to4e.84 at 15psi my egt's would reach 1600*f in 10-11minuntes of continuous road race, with my larger to4s 1.0 i'm not reaching those egt's until 15-16min. hotter charge air means hotter EGT's

Syritis

iTrader: (2)

2 piece E-shafts are typically for increasing RPM. less shaft flex = less chance for a rotor hitting an iron.

believe it or not the housings and iron move when the engine is running. microscopic amount but it still moves. more horse power makes the housing move more. and then you start getting into issues like combustion pressure burring up coolant o-rings. dowel pin kits usually have 4, 6 or 12 (i think) pins to reduce this movement. all the 12-a and 13b motors i've seen have the factory dowel pins in the same place, the FD's have thicker material around the upper dowels due to the FC's having a habit of cracking their irons in this location

right now i have
450ish hp street port and 2 dowel pins
16psi
94 octane (10% ethanol)
turbonetics to4s 1.0
10k mostly track kilometers

my suggestion based on experience and no actual lab proven facts. is that if you have adequate externals such at oil cooling. I/C, fuel system and engine management internal mods are as fallows:

increase oil viscosity at 350-400hp
Oil porting at 350-400hp
4 or 6 dowel pins at 400-450hp
12 dowel pins at 500-550hp
thrust bearing ???-???hp
deep journal bearings at ???-???hp

I beat the hell outta my motor and rarely have the time or money to fix it so for extra caution I use 3mm seals and s4 rotors with a rebalanced rotating assembly.

what do you have to worry about for running 20+ PSI?

Lain0016

1. 12 psi
2. 91 crappy AZ gas
3. Stock Twins
4. 4000 miles on rebuilt engine

Dudemaaanownsanrx7

iTrader: (23)

Dang back from the dead. This thread is over 2 years old.

23 psi
T70
93 pump with water injection
10,000 miles on motor?