Lowering a rotaries compression ratio?

[BenLewisMav]

Also regarding high boost I think heat is the major problem. Thermal inefficiency has always been the rotary\'s weak point, unequal distribution/build up of heat plus running hotter than a piston engine = an unfair sensitivity to intake temps
WI  + Ice to Air IC/Chargecoolers + Methanol + Big oil coolers.. FT(Big boost)W

[Timmy]

The reason we don\'t run high boost is for reliablilty.
Yes 2 bar standard ports with 400bhp will produce more torque than a larger turbo producing 400bhp, look on rx7 club i believe someone ran 10\'s on a gt35r with standard ports this way.
But if you want any kind of reliability you will have to run alot lower boost and than you will have nowhere near the torque or bhp that you would have had if you went for a bigger turbo with some good porting.

[BenLewisMav]

Your answers are on Rx7club.com mate have a search.

Cheers bud I appreciate that, but was hoping to get Prof\'s/people who\'ve already been talking about it\'s ideas

[Prof]

Biggest problem with big ports is the overlap - so if you have boost coming on early, it can leak out your exhaust and cost you power at low rpm\'s.
 
That\'s why the Renesis has side exhaust ports - because it virtually eliminates the overlap and allows the NA engine to make very good power - but the design also relies on the induction system with multiple intake ports and a kind of tuned intake plenum which acts a little like a supercharger helping to suck more air in.
 
So to answer Ben\'s question - it does move the torque and power curves up the rev range, but you will also get a wider power band.

[StavFC]

This has gone ridiculously off topic, from me simply asking something I now know isnt viable, and I appreciate that, to people doing the equivalent of telling me the world if flat after I walked right round it and didnt fall off, lol.
 
I dont want to carry on, but as Prof is so determined...
 

Maybe the point we were trying to make was that without the porting the high boost just won\'t do anything much other than really heat up the intake air pushing your potential for knock right up there.

High boost will do nothing without porting? Seriously? Did you not see my two completely obvious and simple examples?
If the turbo is off the map its mostly heat, if it dets for whatever reason its dead, but saying turning up the boost does nothing without porting is either ignoring the obvious examples staring you in the face, or your just trying to be argumentative.
 

Ever wonder why when you look at what a load of people are doing and think - why are they doing it that way - that maybe - just maybe - these people have arrived at this formula because it works - that\'s not to say that other things shouldn\'t be tried - but perhaps it\'s better to ask why is that not done ?

We\'ve already clarified and ive accepted, that you cant run big boost on stock compression on pump fuel.
Its also simple fact that drag rotaries DO run big boost, often well over 2bar, so im not sure what the relevance of the above is.
 

It seems that most of the high power rotaries overseas that run turbo boosted engines only seem to go over 18/19 psi when they use c16 - pump gas on a rotary with boost just seems to have a limit around that point.

18/19 psi on C16? Funny that, as even ive driven the original Dragon drag car with it at 2.3bar (33psi) boost.
 

No matter what - for bigger torque figures with a turbo - you need to port - simple inescapable fact. Perhaps you should up your boost and see how far you get, as an empirical test - at least then you can get your lump ported out nice after you\'ve blown it

Aside from the fact ive mention my engines ported countless times, and if you want big power of course you want to port your engine, im not talking about MY engine or any other in particular, I can only guess this is another attempt to be arsey with me.
 
Simple fact, you do all the maths you like, but real world fact speaks for itself. Boost = Torque.
Im not talking torque at peak power as you seem to, im talking area under the curve, drivable, midrange, nice to drive, torque.
If you think having huge inlet/exhaust flow and overlap is the best way of getting torque, well, im speechless and wonder if you have any experience of tuning at all. That will create big peak power numbers yes, and at a set boost level it will create high peak torque too, but it will drive like ....e in comparison to the same power created through boost.
 
Of course you CANT do this on a rotary on pump fuel due to the det issue, but not once did I say you could!
 
Just incase you are missing the obvious once again, and I could give millions of examples as its not hard...
 
Restricted small port WRC 2litre turbo engine. 300bhp at 3bar boost. But 550lbft, and that from 3000rpm, absolute weapon to drive.
2litre engine with huge ports, 300degree cams, tubular manifolds, and a GT40 turbo. 300bhp at 0.3bar boost. But how much torque? Id wager barely over 200lbft and absolutely nothing till well over 5000rpm, would be to the extent of dropping out of the powerband on every gearchange.
 
Fairly common ones lately are stock Nissan SR20 engines pushing 450bhp.
Big HX35s running 1.5bar - Under 350lbft and all above 5000rpm, fast but a bit of a pig to drive.
Far smaller 3071s running nearly 2.5bar- over 400lbft and from far lower, giving a bigger curve and a car far better to drive.
 
Our TT.
Map1- 1bar held boost all the way through the revs 275bhp and about 250lbft. Feels a bit slow to be fair.
Map2- Peaks at 1.5bar then slowly drops down to 1bar at leak. Still 275bhp but 330lbft and would leave itself, but on map1, for dead.
 
I really dont know what else to say to you if you cant see whats staring you in the face and dont listen to someone who has real world experience of it.

[StavFC]

Oh, forgot...
 
STREET PORTED (just for prof ) 13B, running a diddy little GT35R at a fairly big 21psi (shame they cant handle on stock compression on pump gas, but thats life), 505rwhp, but lo and behold, thanks to boost pressure, and despite (well, more like thanks to ) not having big ports, 446rwtq.

 
If you cant see whats staring you in the face now Prof (as if my examples above this wasnt enough, as you clearly dont take any notice of my actual personal experiences, lol), well, I darent tell you Santa isnt real either.
 
Shame this went so ridiculously off topic, as NONE of this is related to my original question, lol

[Prof]

Oooh - you just love an argument - I don\'t - I really was just trying to be helpful - but hey ho.
 
I do just have to say:
 
1) The examples you keep giving are all piston engines - not rotary platform - so is it fair to make that comparison - I\'m not so sure.
 
2) You mention the dragon car in response to my post about 18/19 psi on pump gas - I mentioned overseas - dragon\'s car was a uk car if I remember correctly - please read my post before quoting me.  I also said \'most\' - which last time I looked up the definition for that word meant \'not all\' (I am merely pointing out the text here - not trying to out you or provoke argument)
 
3) Other people have posted on here - people with tuning experience of rotaries - and even a respected engine builder - but never mind their experience - you go with your piston examples :Thumbs-up
 
I\'m not out to give you a hard time Stav - I\'m not sure I\'ve ever met you - and I\'d have given the same answers to anyone else that asked - this is a forum after all - and a place where people share knowledge.
 
If you ask a question but don\'t want people to respond - then why post it on a forum. :cool

[chrisJDM]

very interesting thread and some great comments, i think if you want bigger torque your gonna have to drop a triple rotor in there, enough torque for you then?

[Prof]

very interesting thread and some great comments, i think if you want bigger torque your gonna have to drop a triple rotor in there, enough torque for you then?

Or wait for Mazda to make the 16C\'s :Thumbs-up

[BenLewisMav]

This thread makes me want to find a way of running lots of boost for manly torque.. If I build the most reliable WI system ever I reckon I\'m in with a chance  :Thumbsup!

Anyway back on topic, my old street ported 13BT was built by Powergains using low compression Series 4 rotors...


...Which now ironically resides in Prof\'s car!
lol

[Prof]

This thread makes me want to find a way of running lots of boost for manly torque.. If I build the most reliable WI system ever I reckon I\'m in with a chance :Thumbsup!
 
Anyway back on topic, my old street ported 13BT was built by Powergains using low compression Series 4 rotors...
 
 
...Which now ironically resides in Prof\'s car!
lol

:driving Christmas just came early :driving
 
Apologies for the thread hijack  - Ben, you going to be tuning for WI (cutting fuel) or just using it as a safety net ?

[BenLewisMav]

lol.... erm you did know that right Prof??
[Merry Xmas if not :Santa... you\'ve only had the engine for a year ha :Hammer]


Anyway, in a way there\'s your answer Stav -Series 4 rotors.

(And tuning for Water injection, doubt I\'ll reach silly psi for any length of time without it)

[BlitzBoy]

Oh, forgot...
 
STREET PORTED (just for prof ) 13B, running a diddy little GT35R at a fairly big 21psi (shame they cant handle on stock compression on pump gas, but thats life), 505rwhp, but lo and behold, thanks to boost pressure, and despite (well, more like thanks to ) not having big ports, 446rwtq.

 
If you cant see whats staring you in the face now Prof (as if my examples above this wasnt enough, as you clearly dont take any notice of my actual personal experiences, lol), well, I darent tell you Santa isnt real either.
 
Shame this went so ridiculously off topic, as NONE of this is related to my original question, lol

US Dynojet=FAIL :WaveBye

StavFC you have just posted a US dynojet chart they always are show more power and torque by more then 15% to 20% then UK or Aussie dynos, if you stuck my car on a US dynojet I be showing 650hp and touching 500 lbs of torque

[chrisJDM]

bleedy americans always have to big bigger and better :spank

[Prof]

lol.... erm you did know that right Prof??
[Merry Xmas if not :Santa... you\'ve only had the engine for a year ha :Hammer]
 
 
Anyway, in a way there\'s your answer Stav -Series 4 rotors.
 
(And tuning for Water injection, doubt I\'ll reach silly psi for any length of time without it)

I\'d forgotten about the rotors - :Giggle  I knew the engine was street ported - and by all accounts - with the same hardware and ancillaries on the block the dyno results were almost exactly the same - so the lower compression rotors haven\'t resulted in any loss of power at the top end.
 
It needs a dyno run again before I tune for water, as It\'s running just under 1 bar boost now regularly on the street with no issues or overheating, and it would be good to see if I\'ve rescued some of the lost torque from the leaking actuator.
 
One thing I did notice in the graph that Stav put up - that his AFR\'s were going higher than 12 near the peak power (after peak torque) which doesn\'t give much safety margin - that\'s a good candidate for pulling some timing and WI if ever there was.