PORTING (making sense of it all)

[PGiljevic]

So I wanted to start an Interesting thread.

With a plethora of power and rwhp claims n :censored::censored::censored::censored: abound I had a top brilliant idea and that is the standardize the out put down to N/A terms for a few common engines and many people could apply it to their own? and build a up a data base here.

So here is how it follows.

1 atmosphere roughly = 1 bar absolute, so whatever your boost pressure is (psi, bar, kg/cm, horse forskins!) convert it to absolute bar (ambient + your gauge boost pressure) then divide your ENGINE POWER by this. I\'ll illustrate by a few examples of mine.

When you go through and work out how much power your engine set up makes N/A then it is easy to work out how much boost you need to make some big power, fit the right turbo and cooler to keep charge temp under control and other mapping basics this is what you theoretically will get......

eg: ~250bhp 13B N/A on 43psi boost (what will it make?)
(43/14.5) = 2.965
2.965 + 1 = 3.965 absolute pressure
250 x 3.965 = 991.4 bhp!
NOTE: F1 mid 80\'s 5.6bar boost absolute (66.7psi gauge boost) would yield ~1400bhp interestingly EXACTLY what a 1.5lt stock block BMW road car engine did @ 10200rpm

Some 13B engine combos worked out for base power N/A (post up yours) you will need to estimate your engine power! NOTE: dynapack chassis dyno users I have used a figure of 1.15 multiplier on FD platform and this is commonly accepted across the traps who use this type to guess the engine power, its pretty close! > http://translate.google.com.au/translate?hl=en&sl=ja&u=http://www.famspeed.co.jp/mnt/power/index.html&ei=lK6BTeeEJ4mYvAPrpOzICA&sa=X&oi=translate&ct=result&resnum=8&ved=0CFkQ7gEwBw&prev=/search%3Fq%3Dfamspeed%2B13B%26hl%3Den%26safe%3Doff%26client%3Dfirefox-a%26hs%3DMBn%26sa%3DG%26rls%3Dorg.mozilla:en-US:official%26prmd%3Divnsfd


13B-REW (stock standard)
T04Z 1.32 A/R & stock twin turbo\'s tested (on exact same set up)
3.5" exhaust dual muffler (quiet)
9.0:1 compression ratio 45 deg C charge temp (for both set ups) 29psi v\'s 13psi *water sprayed IC and water injection internally on single turbo*
365bhp @ 6700rpm engine power @ 13psi boost twins, same exhaust, IC, intake etc SP specification.
565bhp @ 6700rpm engine power @ 29psi boost Single Turbo, water spray IC, and RR water injection
(29/14.5) = 2.0
2.0 + 1 = 3.0 bar absolute pressure
565bhp / 3.0 = 188bhp
So a stock block 100% stock ported 13B-REW will give 188bhp @ the engine N/A *2.0bar boost*
So a stock block 100% stock ported 13B-REW will give 192bhp @ the engine N/A *0.9bar boost*

FAMSPEED 13B-REW
The new high-flow turbine test (More FAMSPEED RESULTS) confirming my testing on stock ported 13B-REW
ブースト：1.1ｋ Boost: 1.1k 　 トルク：45.2kg/5907rpm 馬力：408.0ps/6692rpm 408.0ps/6692rpm: hp 45.2kg/5907rpm: torque
　 ↓ 10.6%アップ ↓ 10.6% up
ブースト：1.3ｋ Boost: 1.3k 　 トルク：51.1kg/5386rpm 馬力：451.3ps/6697rpm 451.3ps/6697rpm: hp 51.1kg/5386rpm: torque
↓ 4.3%アップ（ブーストタレの為） ↓ (for boost sagging) up 4.3%
ブースト：1.5ｋ Boost: 1.5k 　 トルク：53.5kg/5689rpm 馬力：470.8ps/6664rpm 470.8ps/6664rpm: hp 53.5kg/5689rpm: torque
^^^FAMspeed RX7 13B-REW "tickled up" stock port ports just polished no real timing change "modified twins"
various power levels listed at 6700rpm maximum peak (TCF 1.15) high flow twins
Works out to 194bhp *1.1bar boost* 188bhp *1.5bar boost* @ engine N/A

13B-S5 (mild street ported)
actual engine dyno tested @ 7500rpm
3" exhaust 1 muffler
and fitted with T66 1.00 A/R
9.0:1 compression ratio 1.7bar boost pressure with 2.1 bar exhaust manifold pressure
580.1bhp @ 7500rpm engine power @ ~25psi boost RR water injection
(1.7 bar) = 1.7bar
1.7 + 1 = 2.7 bar absolute pressure
580.1 / 2.7 = 215bhp
So a mild street port 13B-S5 block makes 215bhp @ the engine N/A

13B-S5 or 13B-COSMO (RR street ported)
both deliver peak power @ 7600rpm
3" exhaust 1 muffler
and either fitted with T04 1.32 A/R or T51 deliver following
9.0:1 compression ratio 45 deg C charge temp
549.7bhp @ 7600rpm engine power @ 18.3psi boost S5 variant with T04 RR water injection
633.5bhp @ 7600rpm engine power @ 24psi boost COSMO variant with T51 RR water injection
S5 worked out below
(18.3/14.5) = 1.262
1.24 + 1 = 2.262 bar absolute pressure
550 / 2.262 = 243bhp
So a RR street port 13B-Cosmo or S5 block makes 240bhp to 243bhp @ the engine N/A

SCOOT RX7 "top speed car" 13B-REW Peripheral port "cross port motor"
710bhp on 29psi boost @ 7100rpm (dyno print out on coast down converts to estimated engine power *can provide data*)
HKS T51KAI 1.0A/R
Works out to 236bhp @ engine N/A
and on ~1.48bar boost (610bhp)
Works out to 245bhp @ engine N/A

PANspeed RX7 13B-REW Bridge port
578.5bhp on 18.5psi boost (~1.30 bar) @ 7800rpm (TCF 1.00 shown > 503.1rearhubhp)
HKS T04Z 1.0A/R
Works out to 251bhp @ engine N/A

FAMspeed RX7 13B-REW Peripheral port "cross port motor"
646bhp on 21psi boost (1.45 bar) @ 6700rpm (TCF 1.15 so it actually made 561.7rearhubhp)
HKS T51SPL 1.0A/R
Works out to 258bhp @ engine N/A

Racing Beat 13B circa 1986 (Twin Turbo Bridge Port)
530bhp on 15psi boost @ 8000rpm
3" x 2 open pipes :censored::censored::censored::censored: OFF EAR BLEEDING LOUD!
5 deg C charge temp ICE/Alcohol cooler offset low engine compression ratio
(15/14.7) = 1.03
1.03 + 1 = 2.03bar absolute pressure
530 / 2.03 = 261bhp
Racing Beat bridge port 7.5:1 comp engine made 261bhp @ engine N/A

FULL Bridge Port 13B-Cosmo N/A style primary and secondary
3.5" exhaust 1 muffler *loud*
660bhp on 21psi boost @ 8500rpm 9.0:1 compression ratio RR water injection
Garrett T51 1.22A/R
(21/14.50) = 1.448
1 + 1.448 = 2.448 absolute pressure
660/2.448 = 269bhp
Works out to 269bhp @ engine N/A
Same engine fitted with 7.8:1 compression rotors gave below reading
690bhp on 24psi boost RR water injection
Works out to 260bhp @ engine N/A



RR street port V\'s stock ports

[PGiljevic]

In summary, if your system is efficient and the block can take it! then for each 1 bar increase in absolute pressure or each extra atmosphere you will make 100% more power.

250bhp N/A on 5.6 bar absolute boost pressure = 1400bhp
1400bhp - 250 bhp N/A = 1150bhp increase due to boost pressure
1150bhp/250bhp = 4.6 x 100 = 460% increase in power! simple.
Therefor each 1 bar over N/A = 100% power increase as there is 100% more air, assuming you keep charge temps under control the motor was not built by BDC

As a historical context in 1986 when BMW managed regularly to get 1400bhp in qualifying from their stock block 4cyl 1.5 motors they were pumping 6 lt of water per lap onto the after cooler to keep charge temperature at the normal level of 45 deg C! so their power output followed this linear scale quite well as it did on the dyno when they tested it, you will need to compressor map width and turbine to match before you think of doing :censored::censored::censored::censored: like this, but its been done before in the rotary world.

Typically on a 2 rotor full bridge port engine a GT45R is needed to support 36 psi gauge pressures and keep the relationship in tact, delivering around 825rwhp or so on cars I have worked with. For the higher pressure ratio\'s in Garret Nomenclature you are then looking at GT47 sized units or hybrids to do this.

But for most people who are normal this is interesting to see your power to boost and if your set up is efficient or if you are wondering what you can do with your bits you have. There should be lots of honest 500 to 600bhp cars around, then again lol

[PGiljevic]

Hmm. I\'ve often thought about this exact concept and would have applied it exactly the same as you have but the more and more I thought about it, the more i found things that might throw off the approximation so I pretty much just dismissed the idea.

Have you tested how accurate this is? Maybe it\'s just the way i\'m looking at it but it almost seems over simplistic. I\'m sure it gives a reasonable approximation -  but how accurate is my question?

The two biggest things for me are intake air temp and volumetric efficiency. Obviously i don\'t need to explain the fundamental gas law, but I was also under the impression that at higher rpms, internal combustion engines (n/a) could reach greater than 100% volumetric efficiency so the absolute pressure in the manifold (or combustion chamber) could be greater than 1 bar absolute.

The way I\'m looking at it (and I know I\'m missing some things) is that doubling the absolute pressure wouldn\'t actually double the power.

Sure it\'s a good approximation, but how good?

It\'s 100%

So long as you have the compressor map width and turbine to match i.e. BIGGER TURBO *to match your pressure ratio target, thus power target* (efficiency) and charge cooler big enough for the extra heat rejection. I have proven it in my own testing and that with rotary turbo drag cars I consult on. And its been proven over and over in many piston turbo examples most notable F1 1000bhp era.

Volumetric efficiency of stock ports is around 85%
My Street Ports around 105%
Bridge and Peripheral (many variations!) but say 110% (as used in turbo applications).
NOTE: Power differences are not just a function of this but where the power is made

The match between turbine to compressor (again I test this and have posted up many graphs not Howard Coleman like conjecture and personal theory) is so long as relationships are maintained PORTS are not the restriction never ever have been to ultimate power, all they define is where it is made due to charging efficiency at higher engine speeds.

(Turbo\'s are simple as stated. And ancillaries as well, if you are reading this thread and comprehend it so far you will be all over these basics too.)

The formula and how it works is proven

So the base engine (aside from mechanical strength!) was and is never the issue, its the bolt ons and adaption of water injection or aftercooling spraying to keep charge temperature under control and so long as you have the appropriate turbo its a prefect linear relationship.

It is and can be swayed by these variables:

* If you are greatly reducing ign timing as boost increase
* If you are making vast changes to AFR as boost increase

Then you can have non linear discrepancies of over 25%!!!
But if you run water injected especially these boundary restrictions do not apply

To give you a practical proven example a BMW F1 turbo mapped on an engine dyno here (I have the dyno sheet!) is Australia did 802bhp @ 3.3bar with lambda of 0.79 @ 10,000rpm and at 5.6bar uses the same lambda and water spraying the IC it see\'s over 1350bhp That was the going rate at the time for the qualifying power output at that boost pressure

Well I\'ll be darned :willy_nilly:

I gotta say, the thing I like the most about your posts is that you explain the theoretical side of things and then follow it up with an example that agrees with what the textbook says.

Thanks

That is how I teach (It\'s my profession) it adds credibility and separates the wannabe\'s from the ones who actually have done it

I like many others get sick and tired in forum world of reading crack pot theories or regurgitated information by overnight wonders who have never done anything of the sort. My idea is to understand the theory and then apply it myself, THEN talk about it. And back it up ........... odd concept I know to some lol.

You asked an excellent and insightful question before and I hope I explained it, back when I was doing tests on the standard ports and collecting data on everything I personally saw near a linear rise to the point where there was divergence between TIP and MIP (turbine inlet pressure and manifold inlet pressure) *read turbo becoming too small* so then I experimented with 1.00 to 1.15 and to finally 1.32 A/R turbine housings then to the point of the turbo itself being too small. So that is a critical point and lots of good engineering writing on the subject explains balance of gas flows between turbine to compressor. Second "mapping" considerations which lots dont talk about is excess fuel ratio\'s and spark timing, and tertiary considerations are the charge temperature and knock limitation of the fuel you use relative to the CR you choose to implement (inter related issues to a point).

But if all things are appropriate for the target goal then sky is the limit, so long as you do not exceed thermal capacity of critical engine components or mechanical strength, and it is advantageous to keep rpm low and vastly increase pressure as this is far far less stressful.

Wanted to keep it simple though, but hopefully this explains the "theory" is sound and proven in reality too

[PGiljevic]

More engines added, this time Panspeed 13B-REW 9.0:1 compression ratio engine bridge ported with T04Z as run last year at World Time attack, tuned before shipping to event.

[Brett]

I bet longevity is somewhat curtailed at this point though.  Back in the day it was castor based oils too?  Don\'t see too much of that these days.

Nice write up

[grinder]

my head hurts now..........

[Grant Monkhouse]

Takes some time to read it through. It makes sense. Lots of data to back up the theory too

[Grant Monkhouse]

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?

[Will66]

This theory applies to just about any internal combustion engine.  It rings true with my experiences too, stock port RX8s make about 190 hp at the flywheel which is similar to the 13B-REW.

[PGiljevic]

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?

Yes any engine as wil said.

The 7.5:1 are special factory Mazda racing parts.
The 7.8:1 are Rice Racing modified "hand balanced" S4 turbo versions that I pioneered a long time ago (proven in the Mazda Capella on my web page). You achieve that by porting out the combustion pockets to reduce the compression ratio.
Reducing the compression ratio effects power a little bit on boost to boost application but it makes the engine produce allot more power as its tolerant to much higher boost pressures, inlet charge temps, ignition timing, fuel quality etc etc....... brake specific fuel consumption leaves allot to be desired though! less work in compression stage = far worse fuel efficiency.

Bit off topic, but the main gist is the porting styles and working it back to a figure that can be easily compared

[Prof]

bmw used to leave their engine blocks outside and get the engineers to wee on them, any blocks that were still sound after that treatment were cleaned up and used for the F1 engines.

Good write up - would be good to get some other writeup\'s on what engines were a good build and which were not - in terms of longevity, wideness of poweer curve, etc.

[Grant Monkhouse]

Just been trying to work out the power gains drag car NA power.

They\'re making 771RWHP @ 1.8bar/26.1psi

26.1/14.5 = 1.8 + 1
771/2.8 = 275RWHP NA?!!

Now using the correction factor of 1.15 to get FWHP

771 x 1.15 = 886 FWHP

886/2.8 = 316FWHP NA!!

Now what would this engine make at 35psi??

35/14.5 = 2.4 + 1 = 3.4
316 x 3.4 = 1074FWHP

WOW, I hope I\'ve worked it out right.

[PGiljevic]

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.

[Grant Monkhouse]

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

[Will66]

It\'s in the right ball park but it is relying on 15% powertrain losses.  If you went for 18% powertrain losses then it would be 324 HP.

To be honest, both those figures seem high for a Bridgeport 13B.  But I could be wrong on that.

Either way, the 160 mph terminal speed is exceptional.