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Hi,
Can someone tell me what does a car with upgraded cams feel like?
The main questions:
1. Does the VTEC engagement point change?
2. Does it lose that VTEC kick?
3. Does peak power shift in the revrange?
4. If the bottom end is standard, is the goal to have peak horsepower before cutoff, or peak torque before cutoff?
5. Any other notable differences in engine behavior?
Lets assume the engine has I/H/E mods, a piggyback ECU, and lets say the engine is a B18CR.
Thanks for any help
All counts... Generally yes...
From my experience (pre-tuned ECU, not fully tunable yet).Quote:
Originally Posted by spetz
1. VTEC engagement can be set to your desired RPM. Consult a good tuner IMO.
2. VTEC kick...in my example is much more aggressive (just running stage 1's). If you get VTEC killer cams then it speaks for itself, but with a lumpier VTEC lobe you should notice more power, right?
3. Yes peak power shifts, generally upwards.
4. Yeah you want to aim for peak HP IMO. AFAIK you'll pretty much always hit your peak torque before peak HP, and I'd rather have the HP than the torque.
5. Uses a little more fuel (not properly tuned). Louder. Crazy VTEC crossover (I have other mods too).
Dougie,
What cams do you run?
I am confused as to the hp and torque thing. Hp is always after peak torque because of how hp is calculated (nm*rpm/5252).
And I am wondering whether it's ok to get cams that make peak hp after cutoff (ie the hp will keep going up after cut off) however peak torque is before cut off obviously.
The reason I ask, is one of my daily drivers has peak torque at 1,500-4,000rpm, and peak hp from 4,500-6,000rpm, however past 5,000rpm it has no pull at all.
I run Skunk2 Pro stage 1's.
I didn't know HP and torque were related like that. Where did you get that information? I don't think that's an accurate formula but if you can convince me otherwise please do.
When you look at a Honda engine (being generally small/4 cylinder) you normally get peak torque at one RPM point (not a RPM range) and the HP will peak higher, because the engine doesn't make much torque anyway. Peak HP also comes at one point in the RPM. You might maintain this level of torque/HP output for a certain amount of time (in terms of RPM) but the peak it generally at one point.
It's fine to have cams that make power above your cutoff, but I would advise aiming for a cam shaft that will make power within the RPM range that you can USE, or alternatively increasing your cutoff.
I think the B18CR makes peak torque around 7500RPM and peak HP around 8000RPM.
What car are you talking about that has 'no pull' over 5000RPM?
Torque and power are related like that, as a quick google search will tell you
http://www.ebroadcast.com.au/ecars/A/Power.Torque.html
http://www.largiader.com/articles/torque.html
and one of my favourite articles on the torque/power debate that clears a lot of stuff up:
http://vettenet.org/torquehp.html
Honda engines may make relatively small amounts of torque (due to low displacement), but they make high power because of high RPM
Very interesting read, thanks!
Yes, an engine that revs high will always make a "lot" of horsepower. Hence why small capacity bikes always seem to make so much power compared to their engine size.
To give you an idea, a car with 100nm at 10,000rpm would make 190hp, where we know in reality a even a 1.3 liter carburetor Civic makes more torque than that.
And hence we also know that past 5252rpm the torque can start dropping off yet power can be going up, as the rpm are higher than the 5252 number it will be divided by to calculate power.
The car which has no pull past 5,000rpm but makes peak hp from 4,500-6,000 rpm is a 1.8L Audi A4 turbo (B8).
Which leads me to the question of whether when choosing cams, should cams be chosen for their peak torque rpm or peak horsepower rpm, taking into account the standard bottom end of an engine dictating not raising the cutoff
No idea about the Audi, but how does your B18CR feel past it's peak-torque point of 7500RPM?
I chose stage 1 cams because I wanted something that would be suitable for street use - smooth idle, not too noisy, but a bit of extra power. If I had to choose a part based on peak torque or peak HP I would go for the HP. IMO there is no replacement for HP :)
What engine is it you have?
And how noticeable was the improvement after cams?
JDM B16A, very healthy.
Difference was hard to gauge because I did a full head build all at once. Shafts alone...no idea what the gains would be.
Have a look here if you want:
http://www.ozhonda.com/forum/showthr...Andy-s-CRX-SiR
Basically torque is measured rotationally, but horespower is measured linearly. Because an engine spins around the crank it is impossible to directly measure horsepower. You have to measure torque and then extrapolate the horsepower using the formula given earlier.
I disagree. Especially for tthe street, you're contradicting yourself when you chose the good street cams.Quote:
Originally Posted by dougie_504
Its easier to think of it like this: torque is what gets you moving, power is what keeps you going. When you put your foot down and you get pressed back in your seat, that's torque.
Power is good when you have something light to move. Motorbikes make massive power, but no torque, likewise for Honda's. Torque is good for something heavy. a truck might only make 700hp, but it does it at 2500 rpm and makes 1500nm of torque. Even if you had a 700hp Honda motor you'd be pushing to make 500nm coz you'd be doing it at 8k rpm and it wouldn't work in a truck.
For a street car, you'd want torque over power. Most of the time you're coming from traffic lights etc, so low revs, and that's where you want the pull, and that's torque.
Sent from my HTC Desire using Tapatalk
vtec killer cams dont have vtec lobes.Quote:
Originally Posted by dougie_504
make sure you take account of supporting system to achieve peak hp e.g. 4-1 header with long primaries, larger diameter. shorter, larger diameter IM.Quote:
Originally Posted by spetz
not sure in the relation in valve overlap in terms of choosing camshafts. also, dont forget dynamic compression ratio, larger lobes will reduce static compression ratio?
street car needs torque i very much agree.Quote:
Originally Posted by trism
Quote:
Originally Posted by trism
Yes true, but I didn't want anything extreme that would make my idle rough or mess up my fuel useage too much. I drive the car once a week and it gets rev'd out quite a lot, so the stage 1 cams were IMO a good choice for what I wanted out of my car.
Being a 1.6L I'm not too concerned about how much low-end power I'm getting. It revs out to 9,000RPM and there's plenty of power to be tapped into :)
hey dougie,
what is this stage 1 cams? what makes them so called a stage 1 cam?
Youll find the terminology of "stages" used to descibed cams in every single motor ever built.
Its just an easy way to describe how much more aggresive over stock they are. Normally they go in 3 stages.
Stage 1 is a street upgrade, basically a little bit more lift, a little bit longer duration, adds a few more HP and a bit more torque without the need for tuning, and without making it totally unstreetable and shit on fuel, a pig in traffic etc.
Stage 2 is for those who track their cars often, a weekender or once a month car, but still needs to be reasonable in traffic, and on fuel. Duration and lift are increased a bit more, generally helps to have something to tune to, and you wouldnt do it without having all the supporting mods, intake, exhaust etc
Stage 3 is generally regarded as race only. Massive lift, longer duration, moves the power well up in the rev range, results in the under lump idle, shit on fuel for daily driving. Really only useful with a complete aftermarket computer, all external mods, and internal stuff, valves, valve springs, retainers, all upgraded.
i think we should refrain from using such terms.Quote:
Originally Posted by trism
http://www.team-integra.net/forum/14...-get-next.html
i agree more to the link above.
spetz: check out this link http://www.team-integra.net/forum/14...-learning.html
be wary in choosing cams. make sure it suits your needs.
Sorta but not really the same. That thread is Reffering to stages of total upgrade packages. Just like what youd see in Gran Turismo or Need For Speed, especially the old underground/underground2 games.Quote:
Originally Posted by mocchi
They imply that a "stage 1" intake is say, an aftermarket panel filter, and will net you 5hp everytime, no matter what other supporting mods youve got. "Stage 2" is a pod and a CAI and will net you 10hp everytime, no matter what. etc etc.
This sort of talking about upgrades has only really been prevalent since the real upcoming of the "import" scene, say the last 10 years or so.
The idea of "stage" cams is one that has been around since hot rodders in the 50s, and simply refers to how much more intense over stock the cam is. There is no indicated amount of hp gain, and manufacturers will state they they will only produce a gain when combined with correct supporting mods.
Also remember 'stages' are different for each aftermarket company. I think Buddy Club's 'street upgrade' cam shaft is referred to as stage 3, similar to Skunk2's stage 1.
If you're looking at shafts you just have to see who has what to offer, but that's generally the case as trism stated.
The BuddyClubs are Spec III.
And don't forget Delta lists there cams as 'grinds' ie a 272 DeltaQuote:
Originally Posted by dougie_504
Bisimoto lists them in levels.. Level 1, Level 1.2, Level 2, etc etc.. All the way up to Level X.
Stages imo is a terrible way to describe the increase over standard that an item/process gives.
i agree with you. cam manufactures should be forced to represent their spec's in ramp, lash, duration and lift. and take the time to find out the dynamic ( not static ) compression created, on a factory standard engine. just for reference for people whom have had their heads or block's milled, or weather your using higher comp piston's.Quote:
Originally Posted by Jccck
The problem isn't the manufacturers, it's the consumers.Quote:
Originally Posted by Touge Tom
If everyone was informed, manufacturers who didn't give out these details wouldn't sell any parts.
Yeah, it seems like old school cars, and hondas are nearly the only markets who buy cams in "stages"
I know that with toyota parts, especially for the 4AGE they are always refered to by lift.
i do believe most high end competition honda engines remove the vtec system, especially in the sports compact racing series, drag or track
Not suprisingly, Commodores do everything in Stages.. Haha
Stage 2 Head Package! Stage 1 Gearbox Upgrades! Stage 3 Turbo Package.. God damn they're useless lol
Mugen_ctr i'm fairly sure that's correct, but they don't remove it.. They lock the VTEC permanently on, because the changeover when hitting Vtec would do serious damage to your engine with a really serious Cam!
whats the point of that? you might as well have a SR20 or 4age20v with the same lift and duration cams as what a competition B series would have?
Go look up vtec killer cams.
Sent from my Xoom
i know 'bout them. i just dont see the point of getting a VTEC motor to swap out a great design. to then swap in an less efficient design
low cam is just for drivability/ fuel consumption/ emissions
how exactly do you lock VTEC on? Technically, if the cam profiles don't change, it isn't VTEC. It's no longer variable valve timing.Quote:
Originally Posted by Jccck
I think you guys are getting a little confused.
VTEC is a system where you can run 2 cam profiles on one engine. VTEC Killer, removing VTEC, or VTEC locking, all mean the same thing.
You take away the ability to run 2 cam profiles (economy/perfomance) and are stuck with just the one profile (performance).
In theory, you could they remove *ALL* of the VTEC hardware, sensors and circutry because you basically just running a simple DOHC motor.
that what i meant. The concept of locking vtec is absurd.Quote:
Originally Posted by SlobberGoat
Haha but what about single OHC motor with VTEC?
(just had to ask)
Same story. SOHC VTEC still have two profiles (economy Vs performance). Install a VTEC KILLER cam and you've basically swapped out the 2 profile cam for a cam with only one profile ---> performance. No longer need a VTEC system to switch to another profile (cause there isn't another one), so you just plug up & disconnect VTEC.