Cams, compression, revs and power...


Kozy said:
So now lets look at some 'm4d tizzle' cams, proper gnarly race spec stuff. They can feed your stock B18C to 11000rpm, but have dropped your DCR to the low 9s. Your midrange will SUCK with this setup. So then, the usual reccomended solution is to go and drop in some 13+ CR pistons to return to the stock engines mid 10 DCR. In theory this is great, we have enough flow for 11k, and a stock DCR, so it'll drive around town like a factory car and tear chunks out of ex BTCC cars on track.

Except as far as I can see, it won't...

Can anyone tell what flaw I am looking at here? :blinx:
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I'm actually a bit confused over this thread still. So basically you want to know why your 13+SCR/10DCR huge cammed B18C will drive around like crap at low engine speeds ?
 
No, it'll probably be brilliant at low speeds, I was hinting more at the top end.

It's the practice of taking a cam designed for 10k, and then compressing the **** out of the engine to make it work at 5k that I am questioning.
 
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So you want to know how CR effects the overall powerband of the engine ?

BTW: your "m4d tizzle" cams will most likely make the engine run like **** at low speeds. It probably won't even idle properly unless the idle is raised high.
 
Rich777 said:
So you want to know how CR effects the overall powerband of the engine ?
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I know, or at least I have an idea. The aim was to provoke some thought, get people thinking about why they are bolting certain parts together in a build, and how they are all interacting, and why certain combinations might not work as intended.

Doesn't seem anyone is really bothered though.
 
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Kozy said:
I know, or at least I have an idea. The aim was to provoke some thought, get people thinking about why they are bolting certain parts together in a build, and how they are all interacting, and why certain combinations might not work as intended.

Doesn't seem anyone is really bothered though.
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I am not anyone, but I am someone who is not bothered by it because I do the necessary research prior to putting parts into a build. Its the witches brew we all come up with right? Some witches are good at making a powerful brew, some are not. lol
 
tama666 said:
I am not anyone, but I am someone who is not bothered by it because I do the necessary research prior to putting parts into a build.
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But yet you are still puzzling over that flat spot and why you are struggling to meet your WHP goals... :p

I jest of course. I just thought some people might be interested. I'll go back to my cave now.
 
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I am really interested so don't go into your hole yet lol. I'm on the move at the moment and am using my phone as the net so you'll have to wait untill i get home or get chance to sit down. Keep a strong head, its a very interesting thread :) .
 
Kozy said:
But yet you are still puzzling over that flat spot and why you are struggling to meet your WHP goals... :p

I jest of course. I just thought some people might be interested. I'll go back to my cave now.
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You are correct Sir! I am dealing with the flat spot. lol
One should plan for the worst and hope for the best.
I planned but still got the special prize of the flat spot.
"Its always something" right? But I know where to start hunting the issue and should have it resolved in short order.
 
Rich777 said:
I am really interested so don't go into your hole yet lol. I'm on the move at the moment and am using my phone as the net so you'll have to wait untill i get home or get chance to sit down. Keep a strong head, its a very interesting thread :) .
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Totally agree, this is a very good read...:)
 
My post was not meant to be negative in anyway shape or form bud just adding my 2 pennys. Theory is all well and good but sometimes you just have to get on and try it, I love being told something wont work because it makes you work ten times harder to get it to work. When I started to chat to people over here in the U.K about a genuine 750+whp 1600cc engine most laughed and said '' Nah mate you must be dreaming, even Cossie engines dont make that sort of power and their 2 litre'' you so called top tuners wait and see.........................Not my car but build is very similar

Bart Weiss “True Street” Civic | Evans Tuning Race Cars

Also have a look at what these lot were doing early eighties with medevial electronic control units and very simple turbos and road car engine blocks, in the bmw's case the blocks got pissed on my engineers!!!!!!!!

Turbo F1 engines - How they started, part 1 - YouTube

Listen very carefully from 6.25

All trial and error, and then it all comes back to the saying '' How fast can you afford to go''
 
kozy you know i don't have the knowledge of half the people in this thread. but do you mean. why do people go for mad cam's that are made for high RPM power but then try to make them work hard at mid range so that their car's have a more broad power band and remain a road daily drive / race car.. i've probably got the wrong end of the stick but thats what i thought you meant.

Just trying to get my head around the comment's and i don't think its working my brain is like ...
spaghetti1.png


so i think i'll take a back seat and just read from now on.. this is very interesting stuff though, and i like how you don't accept theory you go at it head on and challenge it.. kick it in the face lol .. Good stuff old chap.. :blinx::))
:jackson:
 
Turbos are a different matter though, there are no limits apart from the depth of your pockets, just make it strong and wind up the boost! OK, it's not that simple I know, but still, it's a different kettle of cod.

NASP is a slightly different matter, there are limits, and it is an art form reaching them. To deny this is IMO slightly niave, how do you think Honda manged to hit 100bhp/litre all those years ago? Trial and error with a big parts bin and hundreds of dyno runs? Hmmm...

I didn't take your comment as negative, I was just slightly underwhelmed with the lack of interest that's all. Seems far too many people coming into the scene now who just want to be told what parts they need to hit 200bhp, and who to take the car to to have to them fitted and tuned. :angry:
 
Topher-EK4 said:
kozy you know i don't have the knowledge of half the people in this thread. but do you mean. why do people go for mad cam's that are made for high RPM power but then try to make them work hard at mid range so that their car's have a more broad power band and remain a road daily drive / race car.. i've probably got the wrong end of the stick but thats what i thought you meant.
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You've got the right idea. It's a common trend in Honda circles, I'm having a look at what the potential downsides of doing this are, and the reasons for those downfalls.

Topher-EK4 said:
i like how you don't accept theory you go at it head on and challenge it.. kick it in the face lol .. Good stuff old chap.. :blinx::))
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That's the thing, even if I spend a few weeks researching and calculating stuff only to find that what everyone is already doing is the best solution, then I am happy that I figured that out for myself and that my theory is probably correct.

If I come up with a different answer, like what I am getting with this cam/compression theory, then it irritates me because I feel it is then something I need to test, and want to test, but lack the resouces to do so! While it irritates me, it is also immensely interesting because I dig further than anyone ever would in search of an answer that nobody probably even cares about, and learn some interesting stuff on the way.

Right now, I'm looking at numerous builds, all high compression, that don't make the power expected, and then others on fairly mild compression that make more power than people think they probably should.
 
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Increasing the degrees of overlap tends to move the powerband up the RPM range. Increasing the overlap can increase peak power, but only if the exhaust system is properly designed and sized to scavenge the cylinder. Decreasing the overlap tends to improve lower rpm range performance.
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http://www.ek9.org/forum/resource-a...-specs-comparison-honda-b-series-engines.html this is an excellent read, that explains a lot, and shows that it`s not black and white when it comes to camshafts.
 
Kozy said:
Right now, I'm looking at numerous builds, all high compression, that don't make the power expected, and then others on fairly mild compression that make more power than people think they probably should.
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Most people when speaking about power an engine made have in mind peak power. Though one might see a +5hp peak but gains 5K-8K could be well over 30-40hp ans significant increase in torque.
 
Kozy said:
Turbos are a different matter though, there are no limits apart from the depth of your pockets, just make it strong and wind up the boost! OK, it's not that simple I know, but still, it's a different kettle of cod.

NASP is a slightly different matter, there are limits, and it is an art form reaching them. To deny this is IMO slightly niave, how do you think Honda manged to hit 100bhp/litre all those years ago? Trial and error with a big parts bin and hundreds of dyno runs? Hmmm...

I didn't take your comment as negative, I was just slightly underwhelmed with the lack of interest that's all. Seems far too many people coming into the scene now who just want to be told what parts they need to hit 200bhp, and who to take the car to to have to them fitted and tuned. :angry:
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I bet the honda enginners did try a few diffrent engine designs before settling on a certain design and probabley scrapped a few in that process. Your not going to work something out on paper then to build it and find out it works just how you designed it first time, I dont care who you are its not going to happen, this is shown to great affect in the video I posted above with one of the greatest race car engine builders of all time Keith Duckworth finding out the hard way:)

As you say far to many people do come into this being told by internet forums and the like what parts or brand of parts they need to fit to reach certain h.p goals and there are far to many internet experts who talk the talk only for you to find out they have no real world experiance, my advice get out there and get building, change things and write down what the changes did with diffrent tunes/settings.
 
Kozy said:
Seems far too many people coming into the scene now who just want to be told what parts they need to hit 200bhp, and who to take the car to to have to them fitted and tuned. :angry:
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This is too true.. I guess it has something to do with they have a very basic knowledge of power and how it relates to movement. for example they know 200bhp is a quick car, but don't have the inteligence, interest, understanding or resources to be able to make up their own mind. and so get advice from people who have seen what the results can be from setup X and therfore go with it knowing what they will get and knowing how much it will cost..

personally i like to be put out of my comfort zone..(its one of very few way's you actually learn something and it gets ingrained into you). but i don't have the money to be able to trial things. but then again i am mixture of both. not having the resources or money to test different setups but i have done my own research into what works instead of asking What cam's should i get to make 200hp etc etc... because TBH that takes the fun out of it..
Kozy said:
That's the thing, even if I spend a few weeks researching and calculating stuff only to find that what everyone is already doing is the best solution, then I am happy that I figured that out for myself and that my theory is probably correct.

If I come up with a different answer, like what I am getting with this cam/compression theory, then it irritates me because I feel it is then something I need to test, and want to test, but lack the resouces to do so! While it irritates me, it is also immensely interesting because I dig further than anyone ever would in search of an answer that nobody probably even cares about, and learn some interesting stuff on the way.

Right now, I'm looking at numerous builds, all high compression, that don't make the power expected, and then others on fairly mild compression that make more power than people think they probably should.
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I admire this approach and only wish i had the understanding you guys have so that i could further my research and knowledge.. this is why i am saving so that i have time and money to be able to study motorsport engineering through the Opne university etc etc.. one day i will be able to have an indepth chat and understand everything you guys talk about.. TBH i don't care if it takes ages to understand and i become qualified at the age of 35... i will be happy knowing i have learnt properly :))!!!

anyway i'll shut up now, carry on with your conversations and i'll take a back seat and take notes :nice:

P.S RS250nut - damm good video thanks for that properly enjoyed it..
 
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