Which Turbo?

[skybusr34]

im no expert. but

    if his car has been ported there could be exhaust and intake overlap.  and if there is alot of exhaust back pressure it will push into the intake stroke as its lower in pressure. then on the compression stoke oxygen level is low. causing low explosion. hense juddering ..

please tell me if thats complete poop peeps and im talking out of my bottom :-)

[DR SCHNITZEL]

I have a .7 ar with a .81 hotside. Even though after one drag the whole sys glows near yellow (its that restrictive) i get no misfire. Up to 8000 rpm. I wonder why yours does and mine doesnt.

[BlitzBoy]

but ive never got a reason for the drastic change in result from piston to rotary.
 
I dont mind not getting a reply, as if nobody here knows for sure you cant expect one.

I gave you the reason but you dismissed it as not being Simples

[Nik da Greek]

How can I listen when I ask for a detailed explanation why something happens and nobody gives anything but abuse?
 
.

Do you never stop to wonder why just about every thread you ever post on on any forum ends up like this? What\'s the one single continuous factor across all those threads? Oh....it\'s you!

Why would that be, do you think? Either there\'s a conspiracy of concerted ignorance and malevolent belittlement aimed purely at a) keeping you ignorant of the answers to your "tuning" questions and b) making you look a c0ck....or you simply have a God-given gift for coming across as an arrogant, insulting, opinionated know-it-all who asks pointless questions just so they can argue with helpful souls who try to answer them. Why don\'t you ask yourself which is the most likely of those two scenarios?

No-one comes on here to try and make you look stupid or to misinform you with deliberately misleading information, frankly no-one finds you interesting enough to bother with beyond the fact that you\'re a standing joke across the entire performance car-related internet community and it\'s funny to see how you react when your buttons are pressed. Once the initial entertainment of that has gone stale, you\'re just left looking a very bitter and inadequate person with little to redeem you beyond the most hillarious and aggressive inferiority/persecution complex ever seen. Please take your internet warrior drivel somewhere else where it\'s just possible you aren\'t already infamous and you may actually be taken seriously, no-one here wants to play your schoolyard games

[skybusr34]

Do you never stop to wonder why just about every thread you ever post on on any forum ends up like this? What\'s the one single continuous factor across all those threads? Oh....it\'s you!

Why would that be, do you think? Either there\'s a conspiracy of concerted ignorance and malevolent belittlement aimed purely at a) keeping you ignorant of the answers to your "tuning" questions and b) making you look a c0ck....or you simply have a God-given gift for coming across as an arrogant, insulting, opinionated know-it-all who asks pointless questions just so they can argue with helpful souls who try to answer them. Why don\'t you ask yourself which is the most likely of those two scenarios?

No-one comes on here to try and make you look stupid or to misinform you with deliberately misleading information, frankly no-one finds you interesting enough to bother with beyond the fact that you\'re a standing joke across the entire performance car-related internet community and it\'s funny to see how you react when your buttons are pressed. Once the initial entertainment of that has gone stale, you\'re just left looking a very bitter and inadequate person with little to redeem you beyond the most hillarious and aggressive inferiority/persecution complex ever seen. Please take your internet warrior drivel somewhere else where it\'s just possible you aren\'t already infamous and you may actually be taken seriously, no-one here wants to play your schoolyard games

ROTFL   what an outstanding response.  . cant add to that one.   nice one:cheers

[StavFC]

Nik- You mentioning forum warrior about me, with a reply like that, is nothing short of hillarious. But crack on, I thought this thread was going back to being interesting but your determined to keep it on the \'lets try and put him down\' side of things. Go for gold, must make you feel better, especially with the other forum members cheering you on like above, thats why you do it right?
 

im no expert. but
 
if his car has been ported there could be exhaust and intake overlap. and if there is alot of exhaust back pressure it will push into the intake stroke as its lower in pressure. then on the compression stoke oxygen level is low. causing low explosion. hense juddering ..
 
please tell me if thats complete poop peeps and im talking out of my bottom :-)

Thats not poop, what you say does happen :yes Thats the fact of backpressure and restriction, works the same in piston engines, more pronounced when you have lots of overlap, and part of the reason all engines dont magically make unlimited power.
But what they dont do is hugely judder and buck and go crazy when this happens, they behave as I said earlier.
Maybe rotarys are different, I dont know why they would behave like that, and nobody has been able to explain why, but id sure like to know, could save people some expensive mistakes.
 

I gave you the reason but you dismissed it as not being Simples

Because thats not simples, what you explained is just backpressure that all combustion engines suffer. I was interested to know why, technically, rotaries seem to go from making power to bucking and juddering like they missfiring, totally different to how a piston engines behave in the same situation.
 

IEven though after one drag the whole sys glows near yellow (its that restrictive) i get no misfire. Up to 8000 rpm. I wonder why yours does and mine doesnt.

Great info :Thumbsup! Well thats exactly what I expected to happen, purely as thats how every other (ie piston) engine ive ever seen behaves when hugely restricted. Power drops off, things get hot, detonation and even engine fail can happen, but missfire? This is the first time ive ever seen that without valve float or a fuelling/ignition problem. And id like to learn why this rotary phenominon exists, as its pretty bloody important when tuning id say!
 
 

Never criticize anyone\'s ideas, get them to show you the data. Until they have real data, they are just another guy with an opinion

[BlitzBoy]

lol Nik you are a legend

[BlitzBoy]

I explained the exhaust gases get ingested into the intake cycle causing the misfire, the 20g housing is tiny for a rotary, a TO4r housing (Dr Snitzels turbo) is much bigger then the 20g it will give different results

[StavFC]

Exhaust gasses get ingested in to the intake cycle to some extent on all setups, the reply to that point as been discussed countless times on this thread already, so saying that once again doesnt explain anything without explaining why the missfire happens on rotaries and not piston engines, as thats what im wondering.
A simple "I dont know" will do, as ive no ....ing idea either, but would love to know.
 
You said your old turbo did it too Mark, to the 20G housing point is moot.
 
Plenty of 20Gs seem to have got 350@wheels elsewhere at 1bar or more. Not 0.5 and 300bhp and it missfiring due to a \'small housing\', which makes me wonder even more.

[sadgoth]

Plenty of 20Gs seem to have got 350@wheels elsewhere at 1bar or more. Not 0.5 and 300bhp and it missfiring due to a \'small housing\', which makes me wonder even more.

I\'m assuming that is on a piston engine though (or in the US where they seem to produce outrageous BHP claims!)

As has already been said, rotaries produce massively higher EGTs than piston engines so the level of increased horsepower from a turbo is lower. The GT4088 on mine is good for 800bhp on a piston block, but the best I\'m likely to see is round 450bhp - 500bhp (and that is on a heavily bridge ported engine!).

I think Blitzboy has actually answered your question several times, he has said that exhaust gases contaminating the intake mixture cause the missfire, now bearing in mind the fact the tose exhaust gases will be VERY hot, there is a chance of missfire or even DET or failing that the O2 level may be too low to allow proper ignition/combustion at all.

Bearing in mind the differences between a piston and a rotary combustion cycle, I think the problem would be less apparent in a piston block as you would be unlikely to see the same volume of exhaust gas pushed back into the combustion chamber.

Now I am not a tuner, I only know what I have been taught, experienced for myself and witnessed in the years I\'ve been messing with rotaries, but the above would seem to be a logical explanation :WaveBye

[Brett]

Unless these setups are all running identical ports it\'s difficult to compare. Also, the very nature of the rotary dictates that symptoms will show themselves differently.

[Sideways_Steve]

HX35\'s are pretty good and can be had for about £450 NEW

However StavFC,

I just fitted one to a 2JZ in a chaser with a friend and it had a T4 Flange not a T3 like you said ?? Possibly a different exhaust housing to the ones you have ?

As for the whole missfire thing above .5 bar on a 20g housing.... Like has been said it re ingests the exhaust gasses duee to not being able to fire them out fast enough.

Due to the fact Rotarys run seriously rich compared to a piston engine this means it does still actually ingest some unburnt fuel and all the crap of the day  along with fresh fuel which completely screws up the mixture, therefore causing your misfire and bag of sh**e running conditions.

Its the same with my last FD, I had it all set up for 1 bar on the twins with good exhaust etc and it ran perfectly.

I fitted an exhaust bung for noise reasons in my neighbourhood due to complaints and the car wouldnt boost above 0.6 bar It would judder and misfire and splutter and jerk and pop and bang etc etc along with completely fouling the plugs too.

this was due to the increase in back pressure (read restriction like a smaller exh housing on a turbo) which was "choking" the engine.

So in short the reason it misfires is down to the poor mixture caused by the choking caused by teh exhaust housing being too small on the turbo. However thats kinda what Blitzy has already said and it does answer your question fully so Im unsure why you keep asking someone to explain it further ?

Unless of course you like typing and causing trouble like a :Typing warrior LOL :Thumbsup!

[mx1311]

Plenty of 20Gs seem to have got 350@wheels elsewhere at 1bar or more. Not 0.5 and 300bhp and it missfiring due to a \'small housing\', which makes me wonder even more.

thats depends on the porting

ive seen t88\'s start backing up on the dyno at 450whp but prev made 500+ whp on the same motor with smaller ports

going back on track with the thread before i get told im wrong/bottled in the face or mounted

i think a to4r/gt35 with 1.0 rear t4 will be ideal

we had one running 475fly with no problems  (to4r)
colum

[col_fd3s]

The guy who owned the car before me had it mapped at Re:worx,
 
it was mapped at 0.5bar and made 304.2 bhp, on standard ports and standard injectors. they were only able to partially map it though from what he\'s told me
 
He said Re:worx put this down to the turbo housing (20g) being too small to dispell the exhaust gasses quick enough, this would create a head of pressure in the manifold, (even if only for a miniscule amount of time) so as the next exhaust "stroke" came around it was trying to force compressed exhaust gasses into a space they physically couldn\'t go into, hence slowing the rotors down and causing the juddering effect.
 
this is just what was said by the guy who i brought the car from, if re:worx or any other tuners would like to add their input we could put a nice little full stop after this.
 
col

[Sideways_Steve]

Makes sense that does