PORTING (making sense of it all)

[PGiljevic]

James is running racing fuel too. I don\'t think they\'re running WI though. They have run the car up to 35 psi but the dyno :censored::censored::censored::censored: itself. So it would be good to see if they got a reading and the figures match through +/- 10%.

It would be good if Jay could give the dyno session details etc. air temp and so on. 316FWHP NA is very high. Even 300 would be high.

The manifold they use is no doubt freeing up top end HP, but that\'s what they need

It\'s a nice set up for sure Waste Gate out the bonnet is a bit extreme lol :burnout

:Thumbsup! More stuff we can add to the thread the better, though some probably don\'t want to share. Lots of the stuff I consult on I cant even dare to post here, but the thread is a good indicator, especially for road car set ups

[PGiljevic]

One thing to consider (most people forget) is that a well matched turbo system (especially when not maxed out) actually works with a positive pressure overlap. On my set up up to 4/5ths it maximum available power I actually had exhaust manifold pressure well under the inlet manifold pressure ! This is very beneficial especially when you are running higher overlap engine combination\'s ........ sadly not many people measure it and they just go about it hit and miss.

For a 13B BP set up you need a turbo as big as a house, typically GT47 or equivalent and when you use a big inlet manifold you don\'t get full boost in quick transient conditions till 7000rpm! or so (I\'ve seen this many times) loading it up in a higher gear it can be lower around 6k rpm, but that is just lying to yourself  (dont forget as boost goes up so does the rpm to reach it, so at 4 bar boost your not making it till 8000rpm in some cars I have seen with 13B\'s and well over 1000bhp!@) totally not a streetable proposition at all unless you are a maniac hahaha.

[Grant Monkhouse]

Full boost by 7,000 rpm if you can rev the car out to 12,000rpm should give a good strong power band. Lol. Scary but good none the less.

I think people will share their HP figures but not necesarily the dyno sheet print outs. As we don\'t want to drop into that arguement yet again.

I think a good general rule is that on a ported motor, street or bridge, 1 bar of boost should give 500HP at the engine, divide that by 2 gives you 250hp NA. Prety good figure for an NA motor I think!

Apologies if you have all ready written that.

[Mir]

Rice, I am abit confused -Sorry. Can you please summarise and write something in a lay mans language. It\'s very hard to make sense out of things, especially, when you don\'t know the meaning of things you read whilst trying to understand a whole paragraph and or sentence.

To my understanding, you have never been a fan of porting and you always maintained that, rotary engine does not need porting? Am I getting it right?

Sorry If I am not getting it at all . Reading your posts are like reading a book of tuning. Loll

Keep up the good work mate

Mir

[PGiljevic]

Full boost by 7,000 rpm if you can rev the car out to 12,000rpm should give a good strong power band. Lol. Scary but good none the less.

I think people will share their HP figures but not necesarily the dyno sheet print outs. As we don\'t want to drop into that arguement yet again.

I think a good general rule is that on a ported motor, street or bridge, 1 bar of boost should give 500HP at the engine, divide that by 2 gives you 250hp NA. Prety good figure for an NA motor I think!

Apologies if you have all ready written that.

It is FAR less stressful on the motor bearings to increase BMEP than to increase engine rpm. Forces on the bearings increase 4 fold for a doubling of rpm, thus to make double power N/A @ 12000rpm you could make 4 times the power at the same 6000rpm simply by running more boost pressure or the same power on half the bearing loads!!!! due to far lower rpm. (hope that made sense?). Any combination between of BMEP loads (to do with boost pressure influencing combustion pressure) and rpm to reach the power target you want/need/dream about! *water injection is proven to yield a greater BMEP with less peak pressure stresses* side note. IE more power with less engien stress.

The same applies to the 13B-REW or Cosmo.

On stock set ups you will reach the rotor clearance limits using only 8000rpm and 32psi boost pressure (stock ports with T4 platform turbo) = around 600bhp, at this point the rotor sides crash! into the side plates! and not even the gay side step on the late model rotors addresses this! still not enough clearance. SO you 100% for long term use need to side clearance the rotors to have sustained high forces on the eccentric shaft and associated bending, otherwise your plates will be screwed and the rotors scored (I\'ll take pics).

So you get to the point where once the engine clearances are in check then the rotor bearings start crapping themselves, and again it is far less stressful to use more boost than it is excess long term rpm.

So it can be advantageous to keep the 13B-REW inlet manifold (Abel Ibara ran over 1000bhp on his 13B stock inlet manifold) before going 20B and making himself broke in the process! both in the R100 and RX7. Keep revs under 9000rpm and just keeping winding the boost pressure into it.

Lots more parts live and ironically if you match the compression ratio, or the fuel spec etc as needed its much more advanageous to increased engine life. :Typing

But to your point, def from the figures I posted above of "normal" set ups athat are durable as proven in track racing not just straigh line or dyno queens, then ~250bhp level is going to be a reliable figure to work with for sure for a bridge port set up (tuning being in the right window of course) :Talking1

[Grant Monkhouse]

Yeh I understand what you referring too. Rotation of any object is going to give the centre bearing/turning point more load. Easiest way I would think of it is the g force Increase. At 2 g it has the same mass but is exerting twice the force etc. I would dredd to think off the forces acting on a bearing at 10,000 rpm upwards!

All this sort of stuff makes me kind of gutted I became an electrician instead of an engineer as its far more interesting.

[PGiljevic]

Rice, I am abit confused -Sorry. Can you please summarise and write something in a lay mans language. It\'s very hard to make sense out of things, especially, when you don\'t know the meaning of things you read whilst trying to understand a whole paragraph and or sentence.

To my understanding, you have never been a fan of porting and you always maintained that, rotary engine does not need porting? Am I getting it right?

Sorry If I am not getting it at all . Reading your posts are like reading a book of tuning. Loll

Keep up the good work mate

Mir

Thanks.

Summary
For the street 13B-REW etc porting is not necessary at all. The engine will be far more responsive and have a wider power band on stock inlet manifold and stock intake porting. I have proven the power and durability of stock motor in my own car...... 4500rpm to 8000rpm you wont beat it hands down.
For racing, and road use, a good street port will match any bridge port (close enough) with none of the negative drawbacks associated with a "race port"
Street ports have merits, but you loose mid range power, just as you do with a bridge port, you mostly port the motor to "extend the range" IE give you more rpm, higher top speed for set gearing or to better match a close ratio gearbox, horse penis inlet manifold etc etc.

That is a general summary as I have seen it. Others can comment for sure and everyone will have their opinions on it
But porting always has negatives for the road. Do you need porting to make a fast car? no is the answer to that, god created turbo\'s to be used as he intended ................. boost it up !

:3gears-lh

[PGiljevic]

I will add something interesting in this thread to help illustrate what I am saying about speed, power, road set ups v\'s track etc etc.

A little off topic but I\'m sure you will love this...........

So who has watched Hot Version Vol 107 yet? *you can youtube it*

Very interesting seeing all the tested weights, boost pressures, top speeds on back straight! and claimed power levels  :shock:

Excellent spread of cars and configurations  :wink:  Nice typo of the RE Amemiya car running a 4.3 rear diff when it has a 4.7 in it lol, but otherwise nice production.

RE Amemiya car
193.064kmh
twins @ 1.00kg/cm 402ps
1145kg

Famspeed
189kmh
twins @ 1.3kg/cm 499ps *where did the 100ps go?*
1153kg

R-Magic drift car
200.93kmh
T04Z 1.4kg/cm 580ps (sequential dog box)
1126kg

Domar spec drift
190.375kmh
T88 1.35kg/cm 570ps (sequential dog box)
1133kg

To pick the most exciting cars, interesting to see dyno dreams don\'t match with reality, very cool to watch the 5 lap race and see the 400ps twins car keep right up to the 580ps car! (within 1 car length along whole back straight up to 200kmh lol)........ guess who won?

Here is a list of very well known cars and their top speeds on the back straight at this track...
2007 17th Annual Revspeed Super Battle at Tsukuba Circuit

***NOTE*** ITS FUNNY HOW ~600PS Nissan\'s (M speed, Best Motorsports, Garage Ito) that weigh much more are 20+kmh faster lol (and that is with larger frontal area, higher drag too)!!!! I do have ALL of these cars on video along with detailed specs of the all as well

    * 1st place- #13 M-Speed R34 Nissan Skyline GT-R (Best Lap: 55.23sec, Top Speed: 227.282 km/h)
    * 2nd place- #1 Garage HRS SUN Auto Cyber Evo CT9A Mitsubishi Lancer Evolution (Best Lap: 55.864sec, Top Speed: 220.678 km/h)
    * 3rd place- #22 Pro-Staff R Magic FD3S Mazda RX-7 (Best Lap: 55.947sec, Top Speed: 217.742 km/h)
    * 4th place- #12 Nagisa Auto R34 Nissan Skyline GT-R (Best Lap: 56.510sec, Top Speed: 227.082 km/h)
    * 5th place- #16 Kurumakobou Decide R33 Nissan Skyline GT-R (Best Lap: 56.630sec, Top Speed: 233.615 km/h)
    * 6th place- #14 Garage Kagotani R34 Nissan Skyline GT-R (Best Lap: 56.833sec, Top Speed: 227.416 km/h)
    * 7th place- #31 Autobacs ASM Honda S2000 (Best Lap: 57.398sec, Top Speed: 188.055 km/h)
    * 8th place- #18 Best Motor Sports R32 Nissan Skyline GT-R (Best Lap: 57.422sec, Top Speed: 220.994 km/h)
    * 9th place- #15 Hosaka Tuning Factory R33 Nissan Skyline GT-R (Best Lap: 57.504sec, Top Speed: 224.346 km/h)
    * 10th place- #17 Keiyo Jiko R32 Nissan Skyline GT-R (Best Lap: 57.658sec, Top Speed: N/A)
    * 11th place- #3 Jun Automechanics CT9A Mitsubishi Lancer Evolution (Best Lap: 57.824sec, Top Speed: 211.640 km/h)
    * 12th place- #19 Auto Gallery Yokohama R32 Nissan Skyline GT-R (Best Lap: 58.081sec, Top Speed: 223.8
    * 13th place- #21 Garage Ito R32 Nissan Skyline GT-R (Best Lap: 58.282sec, Top Speed: 216.650 km/h)
    * 14th place- #5 Varis CP9N Mitsubishi Lancer Evolution (Best Lap: 58.456sec, Top Speed: 211.102 km/h)
    * 15th place- #4 Stillway CT9A Mitsubishi Lancer Evolution (Best Lap: 58.484sec, Top Speed: 204.468 km/h)

[PGiljevic]

If you look up that video and watch it you will graphically see the effect of power band and peak power offset to reality on a race up to 200kmh, you will see a peak top end power increase even when matted to a sequential dog box does not translate to a MASSIVE speed or distance increase pulled over what is a stock motor and stock trans set up only needing to change gear twice.

In my own car with this amplified even higher 565bhp v\'s 400bhp and retaining the same stock power band, it makes for a super fast in gear accelerating machine and that for the street is the best, and that is only achieved with stock intake ports and a low power peak of 6700rpm or so, which means you have a nice and FAT usable power range from 5k to 8k rpm.... that is what makes a road car fast, and even some race cars too

Street ports are kind of the next step.

The idea of this thread is to balance as many of the variables out as is possible to make it easy for a layman to see, just look at the NA power level in RED. And what ever power goal you have in mind you can easy see the boost you will need to use to achieve it.

Ah enough typing for one day!!!

[JayDee]

The 771 is a old dyno, we modified the bridge and exhaust ports and moved the power to the left by about 800 rpm. We could not get a peak reading as the dyno flat lined at about 7.5 to 8k from memory at 740 peak is over 9k remember these figures are at the HUBS, boost is 1.8 bar.
The car did at Surrey rolling road 580 at .8 bar and trapped 145 mph at this level.
The car weight is 2800ish with driver.
Have you got more details of the cars trapping 165 to 170 mph.
Interesting thread I will have a proper read later, just got to map a car!!!

One caveat is that you need to be 100% sure of a couple of things

1. Boost pressure (to record that power figure)
2. Conversion used to guess the engine power

The James car uses a custom intake manifold where as ALL of the cars I list except for the Racing Beat 1986 FC all predominantly still use the stock inlet manifolding, this has an effect for the peak power range. RPM = power and that car with a turbo the size used on an old F1 car lol and the inlet manifold could well mean its 20bhp to 30bhp more than all the ones listed here.

A bit of common sense though never ever goes astray.

There is the best NA bridge ports raced here in Australia in IPRA and the highest ever seen on an actual engine dyno delivers somewhere around 320bhp or so @ 9500rpm. Now remember this is with high compression rotors and ideal AFR in NA form (13.5:1) so typically as you will see any engine mimiking ultimate NA porting will never quite reach the ideal NA power range as its got fundamental tuning working against it as well as some other factors I will leave out as its a bit complex.

This is where VBOX testing or Trap speeds can be your friend

We have a few 28x9 cars that I consult on that do 165 to 170mph terminal at a higher weight than that car? so you can guess the power from that. Some of these cars will dyno out 670rwhp @ 28psi boost *say 2.0bar* (around 800bhp at best guess). So you can use the terminal speeds to good effect especially when you are looking at cars in the exact same chassis "untubbed rear tire" and fitted with a dog box etc etc.

There is no real magic here except that you need to be 100% honest with the figures, and when you are you will see that the numbers all neatly match quite well

p.s. If it sounds too good to be true then typically it is
But ~300bhp I have seen on some cars in turbo form, running full BP, 10,000rpm capable inlet manifolds, higher compression ratio\'s running exotic fuels.

[JayDee]

Didn\'t Abel have his intake extrude honed and also have the throttle body on a 90 degree bend, not sure if that was done for fitment issues or to increase volume of the intake, even though standard intake does not work that way.

[HaywardRotary]

I\'m amazed that the 7.5-1 comp rotors are making the third highest HP NA on that list??!! I didn\'t know you could get comp ratio that low? I thought the lowest was 8.5-1?

Does the theory apply across to 20Bs too?

a 7.5 to 1 compression ratio rotor will not make the N/A power that you convert from turbo figures.
The thing to be taken into account with 7.5 to 1 compression is that there is more volume in the whole of the combustion chamber for more fuel and air so more power can be made from this under boost, especially higher boost levels where if you were running a higher compression rotor you would end up with less actual literal volume for the air and fuel to be able to fill.
So this means that the combustion volume is greater for this type of rotor and the turbo is what increases the compression ratio over what would occur naturally aspirated, so with these two things combined you can make more power than a normal compression rotor.

[Grant Monkhouse]

a 7.5 to 1 compression ratio rotor will not make the N/A power that you convert from turbo figures.
The thing to be taken into account with 7.5 to 1 compression is that there is more volume in the whole of the combustion chamber for more fuel and air so more power can be made from this under boost, especially higher boost levels where if you were running a higher compression rotor you would end up with less actual literal volume for the air and fuel to be able to fill.
So this means that the combustion volume is greater for this type of rotor and the turbo is what increases the compression ratio over what would occur naturally aspirated, so with these two things combined you can make more power than a normal compression rotor.

Thanks Carl, it was/is the only one that didn\'t make sense to me throughout the table for power output/boost/compression ratio although on that specific setup they are running 5*C intake with an alcohol cooler so they have a lot more oxygen in that engine to start with as the others have much higher intake air temps.

Why don\'t a lot of turbo cars run lower compe rotors then? Are their not that many around or is it that the fd rotors are good even at 9.0-1 compression?

Can you remember which rotors you put in my engine? Iv forgot:(

[Grant Monkhouse]

What comp ratio are you going down to with your billet rotors Carl?

[PGiljevic]

a 7.5 to 1 compression ratio rotor will not make the N/A power that you convert from turbo figures.
The thing to be taken into account with 7.5 to 1 compression is that there is more volume in the whole of the combustion chamber for more fuel and air so more power can be made from this under boost, especially higher boost levels where if you were running a higher compression rotor you would end up with less actual literal volume for the air and fuel to be able to fill.
So this means that the combustion volume is greater for this type of rotor and the turbo is what increases the compression ratio over what would occur naturally aspirated, so with these two things combined you can make more power than a normal compression rotor.

^That is a common mistake most mechanics make.

*Your engine capacity does not change by changing the compression ratio mate* The volume does not change, its relationship between volume at TDC v\'s BDC, it is constant it never changes. It\'s a dead area thus lowering compression ratio does not increase area at all, and it is always negative to power at constant boost (on same tuning if you are not knock limited etc) I have proven that myself in real life. But you don\'t hae to believe me HONDA F1 in 1988 went to 9.0:1 compression ratio on their V6 turbo on 2.5bar absolute pressure from the earlier 7.4:1 on 4 bar absolute pressure and earliest efforts of 6.5:1 on 5 bar + pressure on each and every time the power went up (not the other way around) with higher compression ratio *the opposite of what you are saying* its a thermodynamic fact more work in (compression) = more work out, difference in pressure area graphs is easy to comprehend when you test motors and apply thermodynics principles to them So there is no need on methanol especially to lower the static compression it will just cost you power at the end of the day especially if you are using pressures around 3 bar absolute for example.

Anyway I have added another drag specific set up to the equation.
S5 13B (9.0:1 compression stock rotors) with 4 barrel style intake and BIG TURBO on methanol, street ported tested on engine dyno, peak power at 9250rpm and 917bhp on 32psi intake boost pressure (around 2.207bar boost) 286bhp NA terms (if you work it back to peak power with stock manifold of 7600rpm) works out to 235bhp NA. divide (9250rpm/7600rpm). So you see how all of this makes sense