Author Topic: How much Air Flow and Horsepower (Read 4760 times)

TurboD · « **on:** December 02, 2013, 04:14:31 pm »

I have mainly always built and raced Kawasaki's in the past, I currenly own a few SOHC Honda's. I am curious to know what kind of power capability the SOHC has.

Just for Conversation, I have two questions.

#1 a two part question. What kind of airflow numbers could be expected with a good port job and stock valves? And Second part. What kind of flow numbers can be expected on a full out Max effort head? (Numbers at 10 inches would be great, but I can convert)

#2 (kinda goes with #1) How much horsepower has been made with a Max effort SOHC?

Thanks D

Sam Green Racing · « **Reply #1 on:** December 02, 2013, 05:04:12 pm »

I'm sure someone will come up with the flow numbers but what size motor are you talking for Max power?

Welcome to the forum.

Sam.

TurboD · « **Reply #2 on:** December 02, 2013, 05:21:03 pm »

Thank You.

I was curious as to what kind of HP has been made with a Max effort any size SOHC engine?

With the flow numbers you can pretty closely estimate the horsepower that a given engine is "capable" of producing.

bear · « **Reply #3 on:** December 03, 2013, 03:51:36 am »

We have made 134 @ rw.
Our current "B" motor is currently putting out 124.
That's the best balance we've found re; reliability.
Can't help with flow numbers, never flowed any of our heads.

Johno, what does that fancy percuter of yours say?

Cheers,
Brian

http://forums.sohc4.net/index.php?action=dlattach;topic=83748.0;attach=140459

http://s1278.beta.photobucket.com/user/yancohotel/media/PICT1792_zps4dcc0c3e.mp4.html

johno · « **Reply #4 on:** December 03, 2013, 04:36:41 am »

Bear I think your HP numbers say it all

turbo your covering a bit of ground , mild head job with valve standard, full on head job, theoretical HP number based on superflow numbers, not naming a displacement cos the CR boys run 750 hot roadies run 836, 900 , 1,000 and big drag boys going bigger

lots of combos Turbo

TWO bits of reading, There is a thread on dyno graphs and thread on " favourite cam" which had a lot of flow numbers etc

Bear , your not hinting about the new head numbers by any chance

ciao johno

bear · « **Reply #5 on:** December 03, 2013, 04:51:02 am »

Quote from: johno on December 03, 2013, 04:36:41 am

Bear , your not hinting about the new head numbers by any chance ciao johno

I'm a patient man I can wait..............................................for awhile.

Cheers,
Brian

TurboD · « **Reply #6 on:** December 03, 2013, 06:25:30 am »

Bear For the sake of the discussion, and based on your HP I'm "guessing" around 88 to 92 @10. Depending upon the efficiency of your combo.

Johno My flow number question was meant to be 2 questions. First one being, What can be expected (flow number wise) with a good stock valve port job? (no welding)

Second one. What kind of numbers have been obtained with a "all out Max effort" sohc head?

Sorry that my horsepower question was a little vague. I asking about all out max effort NA numbers, to simply get an idea what can be done with a sohc head. Since I'm mainly a turbo guy, if anyone has HP numbers with a turbo or nitrous throw them in the ring as well. Lol

EnginebyAdam · « **Reply #7 on:** December 03, 2013, 08:29:17 am »

Favorite cam thread- http://forums.sohc4.net/index.php?topic=107714.msg1224675#msg1224675
Dyno sheets- http://forums.sohc4.net/index.php?topic=83748.0
cylinder head airflow- http://forums.sohc4.net/index.php?topic=105411.0

The thread I started has good links for turbo's "turbo stroker"
http://forums.sohc4.net/index.php?topic=131098.msg1461795#msg1461795

TurboD · « **Reply #8 on:** December 03, 2013, 10:55:17 am »

I've seen those, good reading. Thanks.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #9 on:** December 03, 2013, 11:00:55 am »

2 trains of thought on 'all out' heads.

The first is a Mike Rieck Stage 4 head. Basically a 'stock' head with some amazing porting and Kibblewhite 5mm stem big valves 34mm intakes and 28mm stock size exhaust.

The second is a Kenny @ CycleX totally reworked race head with 38mm intakes and 34mm exhausts.

I think you'll be hard pressed to find any 'today' flow numbers. I don't know anyone that is doing actual flow bench stuff on today's heads. It's expensive enough to just have a Stage 4 head done when you know it's going to kick ass. If it was me and I had a flow bench then I'd do that since my labor is free but I don't have that option.

Red Good · « **Reply #10 on:** December 03, 2013, 11:14:06 am »

Jerry , what's a today flow number ? Or todays heads ? Explain please I don't get it . Red

TurboD · « **Reply #11 on:** December 03, 2013, 01:51:17 pm »

Jerry I would be interested to know numbers on both those heads, I talked with Ken a few weeks back about his, He said he couldn't remember the numbers right off but had them in the back shop.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #12 on:** December 03, 2013, 02:49:57 pm »

By 'today' I'm referring to what is put together 'today' vs 'yesterday' or 'back in the day'. Let's call 'today' as, say, 2012 or 2013 for the sake of it. Even though we have some great heads put together 'today' I doubt you'll find but a few that are professionally flowed. 'Back in the day' guys like Jerry Branch, Russ Collins, et al wore out the flow benches and used the numbers to their advantage.

Does anyone know of a 'today' head builder that does actual flow work on individual heads and provide the numbers?

After having seen Kenny's head when he picked it up, it looks like a fire hose is needed to attach to the carbs.

Bill/BentON Racing · « **Reply #13 on:** December 03, 2013, 03:48:32 pm »

Jerry Branch put out some #'s years ago,but was stock vs. modified. Was impressive gains, but haven"t seen any #'s on a really modified head. Stock head @ .250 lift was 54.8 cfm. At .450 lift was 58.7 cfm. These were done with carbs and valves. Stock no valve,no carb, was 77.3 cfm. He modified it,deshrouded intake etc. and got 105.6 cfm on head with no restrictions(open port)! Mike's Stage 4 and 3 would be interesting.Kenny's head we saw, really would like to see those#'s! Oh, Mike does have a flowbench!

Bill....here we go!

I got the article on Branch's work, I sure didn't remember those #'s!

Can post if desired.

TurboD · « **Reply #14 on:** December 03, 2013, 03:49:10 pm »

I know most professional Porters doing Suzuki and Kawasaki heads today use and know flow bench numbers.

I still have a couple from when I was working on heads a few years back.

johno · « **Reply #15 on:** December 03, 2013, 06:58:28 pm »

the whole world wants money,
not much of a market for 70's cb honda compared to hyabusa, everybody wants the latest and greatest , competition between the pro race mechanics ensure numbers become important for marketing and also for planning or engine design. Us old die hards playing with nostalga are maybe not competative enough to chase the miniscule gains so dont get too excited about the numbers game.

Also the wheel is slowly turning away from flow numbers as people are now realising that numbers are indicative but can lead you up the garden path, eg bigger holes = bigger numbers but can lead to less torque and horsepower and poor drivability etc and what people want these days is to see flow bench numbers with torque HP graphs to makes sure its not all glitz and glammer.............its a real trap. I havent spoken to Mike about it but I would have a guess thats why he doesnt post numbers as I know he knows the numbers from developing the awesome port shapes. Mike has a very serious flow bench which he uses, not markets. if you get the drift ?

BUT I will be back home on the weekend and will flow my new head MR stage four +, have a chat with mike about it, try and pen a decent report and put it on a new thread for the curious number hunters.
cheers johno

TurboD · « **Reply #16 on:** December 03, 2013, 10:01:25 pm »

I completely understand that people follow the money, and that the number of guys spending it on old SOHC Hondas is growing slim.

My reason for asking about Head flow and Hp numbers, is simply out of curiosity and conversation to factor just how quick one of these old Honda's might be capable of running NA. As of this writing I dont have any plans (or time) for a sohc performance build, if so I would hang a turbo on one (as my name implies) and boost it until the crank, rods and pistons all get pissed off and decide to come out looking for me. Lol

Bill/BentON Racing · « **Reply #17 on:** December 04, 2013, 05:48:10 am »

And they will!

Bill

turboguzzi · « **Reply #18 on:** December 04, 2013, 11:49:42 am »

not 750 sohc data but a good reference....

http://www.cavanaughracing.com/Porting.html

bet larry has done some sohcs too. he's not only into flow benching but uses often a pitot tube to "hand scan" flow patterns in the port. interesting guy.

i recall reading some sohc number in the great speedtalk forum, but cant locate the thread.

TurboD · « **Reply #19 on:** December 04, 2013, 12:28:44 pm »

Yes they do some good work. I know Kawasaki numbers pretty well, and I would say the numbers he has posted are very much on the mark.

turboguzzi · « **Reply #20 on:** December 04, 2013, 01:14:58 pm »

back when i was doing my 750/810 gpz racer he gave me some flow numbers that are quite relevant to a CB750 as the kawsaki motor has 34 inlets stock,
he was giving 75-80 cfm for a stock gpz750 head and told me that getting 100 cfm form those heads was not really that hard.

77F · « **Reply #21 on:** December 04, 2013, 09:02:45 pm »

My father and I split a flow bench and have been slowly trying to learn how not to destroy a perfectly usable cylinder head. lol. I used the Hot Bike Jerry Branch article Mr. Benton mentioned as a guideline for my first shot at porting a CB750K cylinder head with 32mm intake valves wound up with 72 cfm at .400 valve lift up from 56 cfm at .400 stock. The two other ported CB cylinder heads we flowed were F2's one was done at Yoshimura East in the 70's has 33.5mm over size K valves 75 cfm. The other has F2 34mm cycle x super flow valves flowed 75cfm at .400 and was done by a local company. Test was done @ 10. I unfortunately don't have any hp numbers to go with yet. My buddy Justin had Larry Cavanaugh do up a KZ cylinder head last winter when we bored his bike. He Definitely is a stand up guy and his work is excellent !

Regards,

Josh

Red Good · « **Reply #22 on:** December 04, 2013, 09:51:33 pm »

So then port velocity becomes the next hot topic ?

turboguzzi · « **Reply #23 on:** December 05, 2013, 09:42:46 am »

As much as we can all be curious about hp vs. CFM, as one time member mec said, pretty pointless to compare hp numbers without knowing for instance for what kind of octane the work was planned for and i add: is it a drag / hot street / RR motor? what cam/carbs/ex. permutations and more. never mind basic questions like is it for 750c.c. class for AHRMA road racing or a monster stroker stroker taken to +1000? etc.
So turboD, maybe tell us the context of your question

TurboD · « **Reply #24 on:** December 05, 2013, 10:44:51 am »

To explain my question a little more clear, I understand that terms and wording will differ from area to area.

I am curious to know what kind of Air flow and horsepower numbers have been reached with a "maximum effort" SOHC cylinder head and or engine?

"Maximum Effort" In my area this means "No holds barred", "At any cost", "going to the limit" , etc.

In my area we like fast bikes and cars, my street bike that I have been riding for 20 years makes 230 HP with a very easy tuneup. (has not been apart since built 20 years ago)

Now while I am primarily a drag racer, the question is geared some what toward all out drag racing.

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Author Topic: How much Air Flow and Horsepower (Read 4760 times)