Lets talk about cams

[slug_dub]

It should be clarified that Quinn's car is non VVT but he does use the '01 10:1 bottom end, and it is a BP-4W head that has been decked about as much as he dare to push that compression a tiny bit more, and it has ITB's. So its not that comparable to an NA motor with an inlet manifold directly, but is a great combination of the best bits of mostly stock components to make the cams work well.

[madjak]

Manga, yeah the de-shrouding helps lots, but in terms of valve size, the air near the cylinder wall is only partially restricted and will still flow. Overall larger valves will always be better than smaller valves even if one edge is closer to the cylinder wall.

My engine is similar to Quinn's, although it's only a BP-05 head, decked about the same, slightly more compression, but my cams have far more duration and a little more lift still. They have a 0.05" duration of nearly 250 I think. The BP-05 has to be substantially ported to get the required flow but it shows that the early heads are still quite capable once all the radiuses are smoothed out and the ports opened up a bit. Quinn has the ITB's which probably helps a little with the power down low and keeps the power band more linear whilst my modified Honda intake causes big harmonic lumps throughout the rev range. The power range from 6200 up to 8300 is awesome but it would be nice to have a little bit extra up top as the power is still climbing, maybe up to 8800. But it goes to show that a BP-05 head can flow when ported correctly and when everything is balanced well. To get over 200whp with a BP you need everything at it's max... Valves, Cams, Porting, Intake, Exhaust.

Edit: I should point out that my engine is not streetable... but it's good to show that the early NA8 engines are capable of good power when developed to the max.

[datfreak]

Quinn has the ITB's which probably helps a little with the power down low and keeps the power band more linear whilst my modified Honda intake causes big harmonic lumps throughout the rev range. The power range from 6200 up to 8300 is awesome but it would be nice to have a little bit extra up top as the power is still climbing, maybe up to 8800. But it goes to show that a BP-05 head can flow when ported correctly and when everything is balanced well. To get over 200whp with a BP you need everything at it's max... Valves, Cams, Porting, Intake, Exhaust.

I'd still like to make a honda manifold for my na8 engine - Do you think the 'harmonic lumps' in a street car would be a show stopper? Or are they more obvious in your car due to the massive cams/reversion?
sorry for going off topic

[madjak]

I think the Honda manifold is really only a sensible option if you have a ported head with big cams. The runners are shorter than oem so suit engines targetting higher revs via the larger cams. They also have a much larger cross section so need a high flow head to match otherwise you loose port velocity. You can gain heaps up high but can loose a bit in the mid range. Over a stock NA8 intake I picked up over to 40hp in parts of the dyno curve but also made the power curve more cyclic.... so the NA8 intake was restricting the flow a lot but was also far more consistant. Sure the big cams started the cyclic pattern, but the inteference with the Honda manifold magnified the issue creating evwn bigger dips and humps. Fortunately the top harmonic fell right in my target range so it worked out well... pretty much by pure luck really.

You can see the harmonic dips in my dyno sheet below. You can really feel these when driving the car with the 5750 to 6250 rpm ramp feeling almost like a turbo kicking in as the engine picks up over 50whp in 500 rpms. After 6250 the engine is basically at over 180whp all the way up to 8500 and pulls like a freight train. Between 4000-6250 its ok but under 4000 the exhaust gets louder as the overlap wastes the explosions out the exhaust and the engine struggles to pull. Driving sub 2000 rpm is fairly painful especially at part throttle whilst driving through the pits. The car wants to get into a leaping cadence so I tend to back off and coast for sections then power up to speed and repeat rather than sitting at part throttle.

This is the problem with cam choice... you really need to know your target usage and rev range before buying anything over 272 degrees.

Also, I think you need to be in the over 170whp category for the Honda manifold to work well and then I think ITBs might be a better choice for anything but the most extreme track car targetting high revs like mine.

[Magpie]

Posted many times, but here is the ploy of my build with ITB's and 288° Toda cams. The cams have the base circle modified to have over 11mm of lift as well as the ramp angles softened. The engine's third harmonic starts to kick in at 8,500 rpm, hence a change in cam is required to make use of the third harmonic. The same engine but with larger cams (304°) makes over 210 RWHP, but is not very streetable.

In its current form even my engine is a pain to drive on the street especially in peak hour traffic, and I quote Madjak "car wants to get into a leaping cadence so I tend to back off and coast for sections then power up to speed and repeat rather than sitting at part throttle".

Again Madjak is right in his advice, the car is proof.

Filter airbox cover testing by Eipeip, on Flickr

[StanTheMan]

wow. the graph seems to tell a story.
pretty ordinary torque below 4000 rpm. Must really just come on in a hectic sort of way at around 4000 rpm.OMG LOL

I gotta get my head around something here.
youve got 180nm of torque.

my previous version of patchy when she had the Thighe 272 cams she had 269 nm of torque with only 138 hp. which on the surface......is a bucket load more.
Is that actually possible on an B6 motor? I know its only a guide.....but even if the torque number was a little high on the dyno sheet. Is it realistic?

woukd the torque number be different in a different gear?
max speed achieved was 196 km/h max RPM on patchy at the time was 193. it has a 4.1 diff on the standard 5 speed geatrbox. That would sugget to me 4th or 5th gear would have been used ? RPM would have been somewhere around 7500 stand alone ECU was also fitted at the time

for reference

[Alex 2550]

I think this is a great thread to have going.
I have been researching cams and headwork and talking to some people lately trying to get as much knowledge as possible so it would be nice if we had a collection of up to date info here for people to refer to. Hopefully i can add a little by consolidating my research and posting up some questions for the experts.
I have been looking at a more serious cam than say Poncams for example as this will be my main power adder in the build and if i am to get cams i want a noticeable increase. It's not a daily but registered so i dont mind it being a little rough at idle and down low, i also plan to put 10.5:1 pistons in later so i am keeping that in mind.
My research has been on the type of cam around stanthemans, 272/264 10mm/9mm, i think this is about the upper limit for most in a street cam? correct me if i'm wrong.
From my research everyone agrees that to get the most from these cams a tweak of the ecu or a standalone is required but many will run on a standard computer but not at the full potential.
Manga_blue (phil) is a friend near me and i have learnt much from him, i have also spoken to Dann and Stan in regards to cams ect. (that isn't meant to rhyme but hey..... )
As far as head work goes I like Phil's approach of un-shrouding the valve, cleaning the ports up and matching the manifolds i think this is probably what most people would be happy with on a street car and isn't going to cost the earth. as Phil said his port allignment was way off and causing a large restriction, matching alone opened up around 35% of his port area. regardless of the argument of volume vs velocity of flow this would make a positive difference to any car.
having spoken with Phil and reading some of Dann's posts in regards to HLA vs solid lifters it sounds like solids are the way to go if you can afford them and plan to rev the motor hard. i have recently spoken to tighe cams and asked about this and they agreed to go solids if the budget extends that far, they can also adapt any of their HLA profiles to solids and have blanks in stock for the BP. i think Dann said in a post that a cam ground for solids will always be better than the same profile made to suit HLA's and i know Phil has had power drop off after extended periods of high rpm with his HLA's not keeping up.

As far as pricing goes from people i have called or looked at as of june 2016 excluding freight are.
*camtech quoted me $495 for grinds if i supply cams. these were off the shelf grinds on their website and helpful people to speak to with around a week turn around.
*kelford are around $800. this is just prices from their site and it seems Stan is having success with them.
*Tighe $1100. they have a massive list of profiles if you look at the Mazda and Ford sierra range from mild to extreme race only and are happy to grind there HLA profiles to suit solid lifter setups.
our forum sponsor mx5 mania has tighes listed on their site from $995 so obviously try to support them.

I think most people researching this will have a street registered car that goes to the track and if reading this are after more than a very mild drop in cam so for the benefit of people in the future some questions for the experts and knowledgeable are below but obviously with cams there is never a "1 size fits all" answer but this is purely for a database of KNOWLEDGEABLE opinions:

* when does the ports become a restriction for cams? For example are the ports to small for +10mm of lift?
* when should people start considering solid lifters? For example they want to rev their car to 8,000rpm at the track for multiple laps.
* when should the valvesprings be upgraded and when should doubles or upgraded singles be used?
* when does the standard valves become a restriction? i suspect that valves will offer more restriction than the ports but when does this happen if ever on a "hot" street cam.
* when does the throttle body become a restriction? this would not apply to a street car i believe, again correct if wrong. i think the skunk 2 or similar could be cheap insurance though on bigger cams due to harmonics and the throttle shaft but lets hear from people who know im mearly speculating.

i know these questions will have varying opinions and could open a can of worms but lets make this thread a place of knowledge and answers rather than slamming people for what they say.
if anyone has other questions add them and hopefully we can all learn something and benefit this great community.
Bring on the experts and open minds!!!

[Magpie]

POWER (the rate of doing WORK) is dependent on TORQUE and RPM.
TORQUE and RPM are the MEASURED quantities of engine output.
POWER is CALCULATED from torque and RPM, by HP = Torque (lb-ft) x RPM ÷ 5252

Torque (lb-ft) can be derived as HP x 5252 ÷ RPM or RPM = HP x 5252 ÷ Torque (lb-ft)

Therefore for your example of 269nm (198 lb-ft) and 138 HP equates to 3,660 RPM.

With my plot 128 lb-ft and 170 HP = 6963 RPM. Further scaling off Madjak's plot 210nm (155 lb-ft) and 190 HP = 6,500 RPM. Accordingly Madjak's engine is doing more work than mine because of the differences in the builds. Also, the difference in when the harmonics come in can also be seen, mine has no third harmonic.

However you are right from 3,500 it is a kick in the pants and catches people by surprise (Chefie), best kick is above 5,750 RPM

Alex 2550 your questions are what people pay large sums of money for and hence not revealed to the general public. It all has to do with flow through the head.

[Magpie]

Alex 2550 if you are going to do head work on a BP motor use a NA8 head as these have more 'meat' in them to change the head flow.

http://www.hotrod.com/how-to/engine/0210hpp-cylinder-head-flow-testing/

[Alex 2550]

i typed the last post last night but didn't hit submit great stuff coming through guys the dynos are giving a great representation of driveability keep it up. this could maybe become a sticky in the engines section? thanks magpie i have seen the argument of more "meat" as apposed to better angle of the NB head and most seem to say bolt on performance the NB wins if going to be ported or "worked" use NA. by the way i love your build i have read the entire thing

[rascal]

I gotta get my head around something here.
youve got 180nm of torque.

my previous version of patchy when she had the Thighe 272 cams she had 269 nm of torque with only 138 hp. which on the surface......is a bucket load more.
Is that actually possible on an B6 motor? I know its only a guide.....but even if the torque number was a little high on the dyno sheet. Is it realistic?

No, its not realistic..

The torque figures shown on the dyno printout are derived values and not the true torque value, as even in direct 1:1 gear, you still have gear reduction occurring with diff ratio, and tyre to dyno roller size variance.

You wouldn't be getting 269Nm of torque without a hairdryer on the side...

[NitroDann]

Yeah your torque is bs, but that's ok because you can calculate it easily.

Get the rpm and power at the point on your curve which is closest to the top left corner of the graph then calculate it like magpie did or use an online calculator.

Magpie shows that if you have your power and torque you must be making your peak power at 3500rpm, whixh we know is untrue.

[Alex 2550]

useful site for these calculations (and others) is here http://www.ajdesigner.com/phphorsepower ... _ratio.php

[StanTheMan]

looks like I had a massive 134 Nm of tourque

[StanTheMan]

Alex....

you shoulnt put me in the same sentence as Dann

I'm a hack. No idear what I'm doing. Going in semi blind. while NitroDann knows his stuff.