DriveFast7

iTrader: (1)

The new Renesis rotor motor is a real nice piece of work. With exhaust ports in the side plates it greatly reduces overlap and makes a more efficient motor. Better mileage and power.

The GT2 Racers are praying it will be classified and legal in GT2. Peripheral porting it should produce some real tasty power, more power than if the exhast ports were in the rotor housing. This would be something to consider of you want lots of n/a power and have a big pocketbook. Can those plates be bridgeported too?

bill Shurvinton

Does 1200lbs count as super light?

Drive Fast: I think you misunderstand the term 'peripheral' in your last post. By definition this means in the rotor housing.

REVHED

He means peripheral porting the intake with the side exhaust ports.

fitzwarryne

Bloodshoteyes is right, there is far more variation in bridgeport design than in streetporting. I have seen everyting from eyebrow to letterbox, ans a couple which were really J ports in that they went out past the trochoid surface. with a claimed 240-250fwhp.

Thus they will be an overlap in performanc between a large extended streetport and a narrow bridgeport and both confgurations will have moderate fuel consumption.

As heb09 says the way you drive has a major influence on fuel thirst. As the proud owner of a bridgy for a week he rarely goes over 5,000rpm. Once he realizes the potential of a bridgy I suggest he will graduate to higher revs as most lovestruck owners do. and fuel consumption will fall down to the 12-14mpg range. He might even think the Aus$1500 extra in fuel a year is worth the continual push in the back!

Other than fuel consumption the only other main considerations are whether you can learn to live with the noise, and the need to continually slip the clutch in city traffic. OK you can go for a quieter exhaust system but the bridgy hates such constriction and the power output will radically fall. So besides your budget think where you will be mainly driving, for most people not into serious competition, the best compnomise is a medium to large street port. Last but not least, Are there any emission control regulations, and can you get legally get away with the mods?

DriveFast7

iTrader: (1)

bill i think you misunderstood my last post. i was talking about a peripheral intake port.

I know of an engine builder who is dying to peripheral port a renesis motor and i'll let you guys know how it comes out.

bill Shurvinton

Nope. I think your logic is flawed, viz:

assertion 1: No overlap (renesis) makes more power

assertion 2: adding huge overlap (peri port intake) will make more power.


See what I mean? I've not looked closely at the dyno plots but the renesis doesn't seem to make any more torque than an old 6-port would with the airflap removed, especially over your side of the pond (lower emissions in UK so we do get closer to the original claimed HP). Could be wrong.

heb09

yes, I certainly am love struck This morning on my way to work I decided to fill up the tank and reset the tacho. So far I've got 38km's to the tank, with about 10km of that being city driving. I purposely took the city way to work to test the consumption. The needle is still above the full mark Anywayz I'll definitly be posting the results, and If I'm shamed then so be it, but I doubt it. As for the $1500 extra a year, that works out to be $28 a week? ITs more like $2600 a year which is about $50 a week. $2600 is about 3 weeks work for me so who cares!

DriveFast7

iTrader: (1)

swing and a miss.

1. less overlap will make the motor run more effeciently. less exhaust gas to dilute the intake charge. less air/fuel to get sucked out of the exhaust pipe. more and cleaner intake charge to burn makes more power plain and simple.

2. peripheral ports don't just add overlap. they add more intake duration and port volume. that is where the power is attained. currently it also adds gobs of overlap. with renesis there will be much less overlap, even with a peripheral intake port. then see #1

i wasn't talking torque. i was talking horsepower ergo my use of the term "power". we all know renesis puts 238hp to the flywheel, normally aspirated.

bill Shurvinton

1. Disagree unless you state what you are using to define efficiency. At idle the zero overlap will mean that you always have a 10% EGR in a Renesis by definition. With a highly ported non-renensis motor it will be a lot higher. However at load, the renensis will still have that 10% that you can't scavenge, but the ported motor will be able to get that gas out in the overlap period. The fuel that goes out the exhaust (which can be cured with sequential injection) does not reduce power, but merely reduces efficiency.

2. A peripheral intake built for a power application will have at least 450 degrees duration. However you do the exhaust this is mondo overlap.

When looking at a rotary it is far more useful to examine the torque characteristics. Lets take a simple example with some numbers plucked out air. Assume a stock 6-port produced 160HP at 6500RPM and a renesis produces 230HP at 8500RPM (doesn't matter if these numbers are wrong for now). This gives a torque at peak power for the 6-port of 130lbft and 142lbft for the renesis. Or about 10%. So in stock form the renesis is about 10% more powerful.

Hang on you say, what about the 70 extra horses it produces? If you were to put an intake on your 6-port that was tuned for 8000RPM you would get 210HP at 8500. And this is the crux. Within the limits the engine you can move the torque curve wherever you want by adjusting the length of the inlet. The peak torque will remain fairly constant for a given porting. The racing beat work on a street ported 6-port shows this, although they didn't realise it at the time. A mildly ported 6-port, with actuators still in place has a peak torque of around 145lbft with a wrap around DCOE manifold. You can place that peak wherever you want it.

A bridge-port generally has a torque peak nearer the 170lbft mark and a peri is up around the 200lbft mark. So you can build a peri for aviation apps with very long runners and 200HP at 5250 RPM or one for race apps with 340HP at 9000 RPM.

So I would conclude that the torque is vitally important in these discussions, as is deciding where to put it in the rev band

Bill

heb09

done 300km, just under half tank. i wuv my bridgeport. spent last nite cruising with crew so its not like i'm taking it easy.... go the bridgeports

heb09

btw my car was dyno'd, and put 240bhp to the flywheel at 7 1/2 rpm w00t

fitzwarryne

heb09- please post your dyno slip for info.

thanks

heb09

dont have it, it was dyno'd about 2 years ago when the last owner spent $3000 AU on the motor when he did the bridgeport. He said when tuning it they got 243bhp at 7 1/2 rpm.

DriveFast7

iTrader: (1)

doesn't australia use a different kind of dyno? not the dynojet we use here in the states? aus dyno rates a higher number than dynojet?

fitzwarryne

Drivefast7- you are correct the Australian dyno results are about 90% of the US results. Thus, 243hp in Melboune is 270hp in Los Angeles.

REVHED is the expert on the tecnical reasons.

At least the difference is better than that of our currency!

heb09

Drivefast7 said AUS dynos are higher then US? But you say its the other way around? But you say he's correct?
whats the go?

fitzwarryne

heb09 - I said Drivefast7 was correct, Australian dynos use a different technique to measure power. REVHED sometime ago posted information on the difference. I will seeif Ican find his post.

bill Shurvinton

Dynojets are well known to read high. Mustang dynos will read closer to the rest of the world norm.

However chassis dynos are a difficult breed and they all read differently depending on how they are calibrated. tyre pressure, tyre width, weight of car, how strapped down it is etc etc.

Bottom line, unless you are comparing 2 cars on the same dyno on the same day the numbers are pretty meaningless.

Hub drive systems such as the dynapac are considered to be a better bet as you have completely removed the main variable.

fitzwarryne

Bill. I fully support your remarks as a technical statement. However, there is a continual demand on the Forum for hp data and dyno slips.

If there is a need to know, surely an indication is adequate as most people tare aware of the possible degree of error. Carl, REVHEd and yourself well streestress the limitations of dyno results

A difference of 10% between dyno results taken at different times, on different cars and on different machines is irrelevant. However, an indication that on average you can get 30% more peak power out of a street port as against a stock port is useful information. It assists people to make a decision.

heb09

Well the results are pretty good!!! I ended getting 370km out of the tank. The needle was on the red last nite when I filled her up. Not bad for a rotary eh!

fitzwarryne

heb09- thanks for the information. It means you are getting about 14 mpg which is quite good for a bridgy in the city.

My best from a tank was 780km averaging 105kph. That was from Wagga Wagga to Tailem Bend including crossing the Hay Plain where road is flat and straight for what seems eternity.

heb09

woah, thats descent, what soughta setup was that in?

btw I've got a 465 holley on it with a Racing Beat manifold. Both imported from the US

fitzwarryne

heb09- its a 12A stockport with a highly modified Nikki carb (bored venturies, enlarged AP, mechanical linkages,
K&N air filter, modified inlet manifold etc), and a custom header/exhaust system along the lines of the RB you have. The AC and airpump are deleted so it has twin fan belt pulleys. Naturally brakes and clutch have been upgraded.

The engine produces some 125-127rwhp, thus about 160hp at the flywheel, which is not bad for a stockport!.

Every thing is set-up for optimal performance in the powerband 3,000-4,000 rpm which is what I use for cruising at 110kph the legal limit on rural 2 lane main roads. Thus, I get about 28mpg.

In that power range its average hp is higher than that of a bridgeport! In fact the bridgy does not come more powerful until about 4,800rpm. After that the bridgy really comes into its own with 50% more power peaking at about 9,000rpm as against my estimated 160hp at 7,200rpm.

I run on Dunlop FormulaW10 tires which are a hard compound for road use, with a relatively high tire pressure. The suspension is lowered 28mm with stiffer coils and shocks. All this helps fuel consumption and handling at the cost of a harsh ride.

heb09

Sounds nice...
My bridgy has plenty of low down torque, believe it or not... I was talking to the previous owner about bridgys and low down torque and how mine seems to have plenty... he reckons its all about how your feeding it... but i defintly agree theres **** loads more torque top end... however when dyno'd my car did peak at 7 1/2 which means i dont have to rev the **** out of it to get movin It basically feels like powerband when I put my foot down around 4000rpm... and when it hits 6, i get an extra boost

DriveFast7

iTrader: (1)

That's a real nice setup you got fitzwarryne. Sounds like it's all tuned up the way you want it.

heb09, size of chokes certainly affects torque. Rob @ Pineapple said if I put a bigger carb and chokes on my bridgeport I will get 10-20 more peak hp but it'll narrow my powerband and shift it up higher. REQUIRING a close ratio tranny to keep it in it's powerband.

I'm pretty happy with what I have. The torque out of the corners is phenominal. I gain and pass Subuaru WRX's in the CORNERS!

I'll post my dynochart next week. Merry Xmas everyone@!