Because it is not possible to get that sort of power at that boost with a street port. No one ever seems to take 2 minutes to do a simple sum to see if the dyno is making sense.

Many dynos, especially dynojets give erroneous readings. However as they generally read high, people 'chose' to believe them. Maybe there should be a new unit of a 'dynojetHP' which is about 0.75 of a real HP?

Do the simple maths. To get 550 at the flywheel at a pressure ratio of 2.2 would mean that, behind the turbo there is a 250HP NA engine. Go search for threads where people ask how to get 250HP from their natasp engine. Any evidence of street ports getting much over 200 at 7500RPM other than the renesis?

200*2.2 is 440HP which is more like it. Simple calculations to do a sense check. Not hard, and saves embarassment when someone else does it for you.

 

450 HP is possible at those boost levels. Maybe that dyno is off 30-40hp, but why call BS? He has a pretty big streetport. It's no sand paper port.

Do all the math you want. Maybe he was using an AUSSI dyno for all I care. Dynos are made by engineers, and if you want to do calculations and say the engineers that made that dyno are BS, then go make your own dyno. He posted his chart. End of story. Post your dyno chart and compare to it instead of shooting it down.

 

Dynos are made by engineers. However they can be operated by people who have a vested interest in claiming higher power figures than other tuners.

I am BTW an engineer. However it does not take a degree to divide 2 numbers and see if the result makes sense.

 

You seem really angry Bill. I'd hate to see Brian's thread about his engine turn in to a **** fight about you and your dislike for Jeff.

 

This is about basic common sense engineering. The numbers are not possible with that configuration of engine. If any other UK tuner had produced that dyno plot I would have posted the same.

That Brian chose to get defensive/offensive about it (actually I quite like the nutty professor tag, being a cambridge grad, and although my ***** has not won prizes, it has sired 3 children, so my virility is not in doubt) rather than trying to understand why the figures do not make sense does suggest that he is trying to hide something or there is some conspiracy going on.

I'm an engineer and will question anything where the numbers do not stack up. That's how I earn a living. You want angry, see me get started on the people who sell 360HP upgrades for cosworths. One of these was dyno'd on a SUN RAM, which has a coast down capability and is accurately calibrated: on this said '360HP' chip produced 265. The producer of these chips is misleading customers, even ripping them off. And the poor saps believe it.

Now if people are happy to walk away with a dyno plot that purports to give them 25% more HP than they actually have, is that good? As long as they are made aware of this possibly not. If the inference is that the numbers are accurate I don't think so.

 

I have a little hard time believing it, but its not impossible. One of my main reasons is the fastest FD in the UK to date is 10.70 This et. would equate to about 450rwhp. So, the best way to shut everyone up (if you care) would be to go to the track and race because the MPH will not lie. It will without a doubt tell exactly how much power your making eliminating the "dyno" error factor.

 

Well drag racing I do not know about Ernie. So tell me, what do you reckon to the time posted on page 1.

12.0 1/4 123MPH trap and 2.1 second 60'?

IIRC correctly there is a 10.4 FD now as of last weekend. That 10.7 second FD (which I believe has gone a smidge faster) on the same dyno shows 570rwhp. By your reckoning then its 25% or so high as well?

 

Easy enough. 123mph puts you in the 400rwhp range. Drag racing is my speciality as well......
The 10.4 pass with the 470rwhp would be about right in a 2800lb FD with a 1.5 range 60'. Don't take me wrong. Im not doubting your numbers. I was a bit skeptical, thats all.

 

Intersting **cough** discussion!

Out of interest, how do you ACCURATELY calibrate a high horse power hub or wheel dyno? Presumably it should be easily done, since these machines are sold as accuate measures of hp?

 

HI Ernie,
How much power would a FD have that run 10.4 at 138 with a 1.65 60'?

Thanks

Jason
P.S. with a standard box, and slow gear change

 

Thats a healthy mph! I would have to guess a bit over or just under 600rwhp.

 

Ya know... Just being devils advocate here... dont drag race myself. Road race... lot of drag races combined with pissing contests to see who has bigger ***** when it comes to braking....

Anyhow..

I myself REALLY dont like throwing out HP-VS-ET numbers... I know some people who cant drag race very well... and others who can. I have seen a ZX-6 do a 10.8 in the 1/4.. a close friend did it regularly a coupkle years ago.. Me? Cant go that fast.. 11.5 on the same bike same day. Same launch speed same shift points.. etc.. he is just that much lighter/faster/carrying the front wheel lighter.. etc.. etc..etc..

Drag times are not real accurate.. Are they shifting early? Are they coming out of the hole soft? Sooooooooo Many factors to an ET. BUT..

HP on the Dyno? Man... getting on his case for that... /sigh. Always a critic in every crowd.
There is a nice TII I know of in New York that was making 425 to the wheels with a Wolf.. and a stock motor with I believe a T61? turbo. Not a lot.. but nice for a stock motor.
Then again I have watched a FD with a LOT LOT LOT of port and a T-66 Only eek out 425.. And REALLY pushing hard to do it... cause it was OUT of tune.. WAY out of tune. Looked good to the owner.. who was happy.. but man.. it wasnt very close.. EGT was nuts.. AF was way off.. But it made a bunch of power and he didnt want to let the tuner mess with it... /shrug

I think that if you dispute his numbers.. bring a car.. dyno it on the dyno he was at.. OR.. PAY to have him dyno at one you like!! Then you can see..

(em hands cheese and crackers over)

(OK going back to work)

 

http://www.speedworldmotorplex.com/calc.htm

I think the 1/4 mile MPH and weight of car is the best way to determine HP. It's real world numbers. I dynoed at 400rwhp in my first gen. There were some that said no way. car was 2720lbs with me and ran 121-123mph in the 1/4 mile. Et was 11.6 "but" with a better 60' my et would be around 11.3. If those numbers were used in the link provided, everything matches.
chuck

 

I prefer to say 'always an engineer in every crowd'

Is is so hard for people to think about the basic assertion that, whilst repeatable, a dyno may not actually be reading in Horsepower?

 

According to the calculator I have 450 rwhp and 531 fwhp.
I'm booked in on th 17th June to map/dyno my car elsewhere. Will be interesting to compare with my previous for some no doubt.
I'm back at the track on 17th June so will keep all interested informed of my progress.

 

Just used the calculator to find out mph at what rpm.My 12A will do 472mph at 7500rpm! in 4th gear.Also says it had 385 rwhp,that's before I put a GT42 turbo on it.Brian's had it now!

 

Ummm maybe I can offer you some examples of a dyno day we had here last week on DD machine (Its accurate)

My customers car did 320rwkw last time on it, this time it did 325rwkw (436rwhp) this was with 2 psi more boost (turbo fully maxed out comp wheel cant deliver any more grunt) 58mm odd comp wheel @ 23psi.

Now we ran a whole heap of cars on the day....

RX7 NA 13B bridge port 13.0:1 AFR fairly loud exhaust (220odd BHP engine from my estimation)
192rwhp

RX7 std turbo/engine, 3" exhaust bigger FMIC 13.5psi boost...
269rwhp

Sigma 2lt turbo 18psi boost FMIC
287rwhp

RX7 TO4, 22 to 23psi, 58mm plain bearing turbo, FMIC std port motor 60000km old, pump fuel WI, CDI
436rwhp

RX3, 13B street ported GT35/66 or TO4Z roller brg turbo ? (not sure exactly on turbo), FMIC, C16, 18.7psi boost
476rwhp

From the above examples on this dyno that is the same as BNA, I would say it is very likley that he did make 470odd rwhp at that boost on a large frame turbo such as he has and also looking at his porting. For the above figures I would use a multiplier of about 1.15 to 1.20 to have a rough estimation of the actual engine power. I can tell you that 436rwhp on a Dyno Dynamics machine in a 1000kg Mazda is a very fast car that will turn tires in 3rd gear in a straight line !

Hope this helps.

BTW your porting looks nice

 

Yup I think people have jumped the gun a little here, I say his figures are achievable and true, simply look at the examples that I posted from last weekend, all these cars ran infront of me and the best thing is its all relative, I know for a fact that the silver car I prepare is at its limit and making around 530+bhp (engine power)... the other RX3 that ran just before we did made the power shown on race fuel (tune up to suit) @ a lower boost with more efficient turbo also on a fresh healthy ported engine.

BNA's power is very believable just on these examples alone. NOTE also the two 400+rwhp turbo cars are Series 5 or second gen motors (std intake manifolds), the S6 as BNA runs has potential to make even more power @ same or lower boost due to bigger inlet runners and better inlet manifold........ I'd say his power figure is good and where it should be for that set up, probably should be even higher to be honest with you.

 

I have ported upper and lower intake manifold to help with flow at high boost/ high rpm. Flow in and out of ports are based on more that just when in opens & closes, so it is not enough to say it's a streetport so it can only make this much power at a given boost. Inside the port port design and runner size etc all play their part too
The car was only tunes with 105 octane race fuel as I had a problem with my water injection at the time. This is now sorted so I expect to be able to run a litle more advance with my water setup & race fuel together and hopefully make even more power than I currently have.
Real world application is where it counts. Don't believe that power is posisible at that boost. Only way to prove your theory is to get a t51 have same enginge rebuild quality, same port size design, same manifold exhaust etc etc
and tune the car the same. If that can't be done to disprove how much power a given application makes then nothing will.

 

I think what is being missed here is that turbo engines when they are set up as free flowing set ups perform more efficiently than NA counterparts, you get better BSFC (if not fuel dumping) and better volumetric efficiency due to good relationships between exhaust back pressure to intake manifold pressure, another effect could be the better charging efficency as well... Its in there some where but I can tell you it definatley exists as the gains from a turbo rotary v's a NA one are great, when things are in harmony the turbo street ported engine can make ridiculous amounts of power !

You only need to look back in history to when Racing Beat struggled to make 530bhp @ 8200rpm with ICE/Alcohol Intercooled bridge ported twin turbocharged 13B's running 15psi boost through an open side exit exhaust system. I make that with a stock std S5 turbo engine 60000km old **** box running 22psi two air to air S5 intercoolers welded together and front mounted on 98Ron pump fuel and water injection @ 7000rpm ! There is something tobe said for combinations that work.

You only need to look at the NA bridge ported motor that struggled to make 192rwhp and we made 436rwhp thats over 127% more power at lower revs same day same dyno, from my own extensive NA experience that engine combo would be making no more than 230 flywheel HP in that trim (semi street legal) so draw your own conclusions from that, and like I said another competitor made 476rwhp on only 18.7psi boost with a fresh motor, street ported and better bolt ons running race fuel tune.

There was even a V8 there 5.7lt (late model LS1 type?) that in tuned form makes over 400bhp @ engine, he did 360rwhp @ 12.8:1 AFR... His motor was originaly a detuned 310bhp motor delivered formthe factory and he had a sports exhasut fitted, induction mods and the computer reprogrammed to bring it back up to the high performance factory model spec (330kw or over 400bhp).....

Long story short the dyno we used was accurate to my mind and the cars we had there all performed one against the other in a relative environment and the numbers add up to me for what I was expecting. Turbocharged street ported rotaries are great devices, and are more efficient at making power than their NA counterparts that is without doubt. I dont know exactly what it is that makes it that way and I will be conducting my own test on my vehicle to pinpoint in greater detail why these things can perform so well when certain conditions (parts setup) is just right.

 

Bill, it seems to me there are more factors involved in comparing a streetported NA motor to a streetported turbo motor than adding in the additional atm. of pressure available. I don't see how simple division is going to work (ie. 470rwhp turbo @ 1atm. boost = 235rwhp na w/ no boost.)

For one, I would consider how important intake air velocity is on an NA streetport. You can't just port big and expect power- you have to match the intake mani. length and increase the engine RPM in order to get the velocity to support filling the engine w/ the bigger ports.

When Dave Lemon @ Mazdatrix was developing the 6-port motor w/ the aux and 2ndary ports siamesed so it was a 4 port "street port" motor for the rules of the racing class he had a hard time playing w/ manifold lengths (intake/exhaust) in order to get the peak torque under 10,000rpm. He needed to limit RPM for reliability as the race class allowed only "limited" internal changes. It is rumored the leading cars in this class are running more than 200rwhp- you can bet he wasn't going through all this effort and reliability issues if the siamesed 6 port wasn't showing promise of making more.

A large streetport 3rd gen motor has a LOT of port area (consider how tiny even max ported NA primary ports are), but one doesn't need to worry about intake air velocity since the turbo keeps the velocity up and the power will peak at a far lower rpm than the same ports NA.

In another thread you mentioned the same RWHP with a BDC half bridge S4 TII engine was believable? I was confused because it seems to me a large streetport 3rd gen has more port area, better flow and timing dynamics than a BDC half bridge S4 TII. The 3rd gen iron has a lot more material at the top of the port before you hit waterjacket than the S4. If you cut the long 3rd gen port 2-4mm into the cornerseal track on all 4 ports you gain more port area than the small shorter bridge on the two 2ndary S4 ports that don't even go into the water seal groove and have to keep the inner cornerseal track for strength. Not to mention the flow dynamics are better for the larger single port than the port w/ small bridge. The intake opening/closing timing on the 3rd gen streetport is going to suit the stock intake manifolds length A LOT better than a half bridge on stock TII manifolds as well.

Others have made similar power at similar boost and dynoed and raced to back it up. For example Kabooski made 480RWHP at 15psi and 520RWHP at 20psi on his streetport and is pulling wheelstands and the high MPH you would expect w/ his power in his 2nd gen.

Being sceptical is a good practice, but I think asking about the details of their set-ups might help one make the power they are.

 

The volumetric efficiency and boost will effect the BMEP of an engine, people tend to take a lot more care in optimising the volumetric efficiency in an N/A engine through port timing, velocity and wave tuning etc as it is the only way to increase BMEP (ignoring AFR's and ignition timing) where as most turbo engines get bigger gains from simply winding up boost levels without a great deal of volumetric efficiency optimisation, some builders do seem to get very good volumetric efficiency out of turbo motors and make good power with relativly low boost levels ie Judge ITO

 

Went dyno yesterday but not good news.
Found my front secondary injector lifts about 4-5 mm under boost and all the mixture come spraying out right next to the hotside of the turbo.
Only went up to 6,000 rpm because of this and obviously stopped all actvity once it was spotted.
Car will make lots of power.
Below is a comparison of previous dyno two weeks ago at reworx at 1.2 bar
& yesterday's at gforce at 1.35 bar.
The comparison is only up to to 6,000rpm due to the injector problem.
reworx 4k 110 4.5k 170 5k 250 5.5k 370 6k 430 6.5k 490 7k 535 7.5k 550
gforce 4k 150 4.5k 205 5k 315 5.5k 450 6k 485
The above is flywheel horsepower.
It looks to me like the two different dyno at 1.2 bar will read very close to the same amount of power output.
Dyno part 3 in a few weeks time.

 

Hrrrm. 7% increase in boost gives 36% increase at 4K, 13% increase at 6K.

Can we assume that there was a lot of room found for improvement in the tune?

 

At 6000 rpm is where I had the problem hence the lower % of gain.