hey,
ive been searching for a new turbo for a while now but im not sure what i should get. i would love to go for a borg warner efr turbo if there is one that fits for my application.

​​​IWG would also be preferred but im not sure about boost creeps.
​​​​​​
ideally it should do about 280 flywheel hp or lower on low boost as thats what i have in my spec sheet (its really hard to get it over that amount as i live in germany and tüv is really annoying)

i streetported the engine and installed a much larger v-mount intercooler so that shouldnt be a problem and i also installed 800cc primaries and 1200cc secondary injectors. Everything runs off a Haltech Elite 1500

what im looking at at the moment is a IWG EFR-7064 but that might already be too big for my targets

If you could make some recommendations that would help greatly.

 

Honestly, if 350 flywheel HP is your max target, is there a reason you are considering a single turbo at all? A properly setup stock twin turbo setup can easily hit that goal and have excellent response.

Eric

 

280-350 FLYWHEEL hp can very easily be obtained on a stock set up with an exhaust and intercooler. If you are currently single turbo, it would be advised to convert back to twins. Any single turbo set up you use to achieve those power levels will not be good at all.

 

woops totally forgot to mention its an S4 FC

 

you might look into something like a BNR upgrade. either from BNR or you can build your own, https://www.rx7club.com/2nd-generati...-parts-921510/
you might skip the first few pages, the new stuff is later

the big plus to these style of turbos is that they can be externally stock, so no trouble with regulators

 

that would be awesome but it would mean reusing the oem parts. my manifold and turbo have some slight cracks that im worried might cause issues in the future.
also i would have to deal with the tiny wastegate. i already bored it out but i still have to limit my dbw throttlebody to 34% to keep it from boost creeping.

lets say i put a efr 7670 on it would it be possible to reach 280 flywheel hp on a low boost actuator. that way i cant just use a boost controller to reach more power but still hit the power in my specsheet if needed

 

It's possible with a 7670 IWG EFR
Keep in mind you will have to run a 3 inch dump pipe and a 2.5 inch main exhaust system to ensure it doesn't boost creep. That will ensure you can make your 280 Flywheel HP on the low boost canister on around 7 psi.

I would actually recommend going smaller I would do the 7163 for that power goal.
Better response etc

 

​​​​alright thanks for your help. im running a 2.75" exhaust at the moment but with a catalytic converter so i think itll work.

 

You can always chuck an orifice plate in the exhaust for testing and either run pressure differential tube or a separate map.

 

edit: started to recommend the Garrett G30 or similar near-equivalent Pulsar 5455, but for IWG on a div T4 you can’t the BW EFR.

the exhaust size is ok, the flow rating and temperature limit of the cat is the question. Since you’re in Germany, the HJS cat converters can’t be beat either, especially if you can use either the 200 cps, or my preference is the 100 cps motorsport converter.
.

 

yep i have a 200cell hjs tuning catalytic converter installed

​​​​​​the guys at hjs recommended that one for me

the motorsport version is pretty much impossible to drive legally on the street it was already a hassle to get the 200cell tüv compliant

 

my little calculator shows that 280hp wants a ~66mm exhaust, so you should be ok there. cat is likely to be ok too. you will want to check Post Turbo Backpressure though.
it also wants 4x700cc injectors at around 80% duty

my ECU says i was doing 274hp at 6880rpm, 7.74psi of boost, which is either flywheel HP, or complete bunk. target AFR is 11.3 in that cell, and its pretty close to that. actual injector duty was higher than the calculations, TBD on why that might be
mine is a stock REW engine, giant intercooler, stock S4 turbo. 70mm DP into a hollow cat and 50mm x2 cat-back. post turbo back pressure was high, 7psi, response was not great, although its quiet.
new exhaust is overkill, and i haven't tested pressure yet, but its acting like its got no backpressure. response is great, boost control is out the window...
i predict peak power will go from 274 to only 280 though, pretty sure i just moved the restriction from the exhaust to the turbo...

 

since we're posting David Vizard stuff, this is his exhaust thoughts overlaid with Mazda's data and some math.
https://www.rx7club.com/naturally-as.../#post12568793

for a turbo the post turbo pressure should be as low as you can get it, and the pre turbo pressure is related to the intake pressure if that makes any sense

 

it would be 2.9 cfm per hp for us.

that’s why I ran the biggest HJS 100 cps motorsport cat on my NA RX8 for the emissions-compliant race class along with 3” OD 20 Ga piping. It passed OBD2 monitoring without issue, but technically was not EPA or CARB compliant. I’m not familiar with the TUV standard. On the surface that may seem extreme, but since there’s no exhaust harmonic resonance tuning on the Renesis due to zero overlap port timing, combined with how the Renesis exhaust port closes, then the only thing you can do is minimize the back-pressure as much as possible.

There’s always at least one person who will pop up and claim/argue otherwise, but even David Vizard himself would agree.
.

 

i thought about the Rotary having a different cfm/hp than the piston engine, although i could also argue both sides, so i just left mine at the 2.2 that Mr Vizard has.
how did you arrive at the 2.9cfm?

 

id assume he added 30% on top because the rotary uses that much more air compared to a piston engine

 

bingo, it theoretically takes that much more air on our wankel to make the same piston hp

in reality it may vary a bit, but should be close enough for throwing either horseshoes or hand grenades on an intrawebz forum
.

 

it is a ballpark number anyways. if you go too low, the car will probably just be a little quieter, and you'll loose a little bit of power (how much is where Mazda' chart comes in). go the other way you gain no power, and its probably going to be louder.

 

well not really; those are NA engines from many decades ago and which side port configuration is on the one maybe, and depending on all the particulars on the turbo engine this person has, it’s not likely to match at all. At best it signifies a trend between the an NA side port and an NA PP engine relative to the magnitude and difference in how the two are affected under those conditions.

but maybe my head is on backwards and I’m missing the obvious; not sleeping well recently and my night and days are all mixed up, and maybe my thought process too.
.

 

-wrong thread topic-

 

i was reading about the 'Silver Arrow' Grand prix cars, they used lots of boost, with non gasolines. they called it a two stage supercharger, and it sounded to me like they had a high speed and a low speed blower, but no
its small super charger into a big one, so its what we would call compound these days.

invented in 1937! first used in 1938. so its OLD

 

The 1st use of the Wankel rotary was as a supercharger to boost an NSU 50cc scooter for a top speed record in 1956.

 

wth, I had deleted that post from this thread and even wrote -posted in wrong thread topic-


.

 

In your user settings for the forum, you can disable the 'related threads' thing where it will auto-scroll down to a different topic. (screenshot below)

 

that doesn’t have anything to do with me realizing that I mistakenly posted it in the wrong thread and then deleting it, having seen it being revised/deleted along with me stating why, and then it switching back to not being deleted.
.