Stock cam vs schneider 292 vs "Rock the Banshee"

[Blind_Drifter]

Why did you only rev to like 4800 but with the stock cam you almost revved to 6?

[chiplee]

That is not as much as I expected but still shows how much a cam can do for you! I will note that My schnieder 292 was off 2 to 3 deg and I had to use an adjustable cam gear to set up correctly, I don't think you will net another 20hp but I would be suprised with a few adjustments if you couldn't find another 10 anyway...

 

I can't tune like you guys so I don't spin it to 7500 man. It's just not that important to me. not worth the risk. This car is a f'ing blast around town at 20psi and I'd really like it to stay together for a while this time.

I know what you mean longevity means alot! my car is in pieces from the last full power run so keep it together!

 

yeah, I looked at your graph pretty thoroughly and what gets me is that you did it at 28psi. Mine was at 20. I have a degree wheel and dial indicator but I really just don't feel like pulling the radiator to degree a cam with the engine in the car. Maybe when I put my Griffin radiator in I'll do it.

 

this is the first time I've been to the dyno where the tech insisted on driving the car but it worked out well. I noticed during one of the runs that the throttle wasn't opening the whole way. flooring it was yielding about 80% throttle, which I confirmed on the digital dash of the hawk. I think I'll leave it as is for the roller cam to minimize variables but after that, I'm going to fix my throttle linkage and see how it acts. actually I'll probably do it in the same visit to the dyno, once I get a good pull on the roller cam since this local shop has a two hour minimum. I'm also really looking forward to tuning in the snow performance boost cooler. I think I'll have time to do that in the next trip to the dyno as well, after the cam comparison pass is made that is.

 

If I don't make 350+

[chiplee]

Why did you only rev to like 4800 but with the stock cam you almost revved to 6?

 

it was getting lean on that run. the rest of the runs I told the tech to get out of it at 5500 figuring his delayed reaction would make it actually be off throttle no later than 6

[Brown]

Congrats Chip! Awesome run!

[JustPaus_88TSi]

Why did you only rev to like 4800 but with the stock cam you almost revved to 6?

 

it was getting lean on that run. the rest of the runs I told the tech to get out of it at 5500 figuring his delayed reaction would make it actually be off throttle no later than 6

 

 

It's a bit nerve racking watching someone else flog your car, right?

 

 

Congrats on the car brother.. I wonder what you could do if you could put all the time you wanted in it..

[pagemo]

yeah, I looked at your graph pretty thoroughly and what gets me is that you did it at 28psi. Mine was at 20.

I actually only ran mine to 18psi on that pull I wouldn't run over 21 or so with out race gas or meth inj I was running 8.4:1 and even 18 Psi lifted my head but that was my fault so :cry:

definately get that throttle plate open who knows what that is costing?

Anyway great pull and keep us posted on the roller cam and the snow system!

[heefner]

Some of that power increase can be due to running 13.5 AFR. Thats a little lean to be running at 15+ psi.

 

I'm really confused with your results. They contradict everything about that cam.

1- Schneider claims that cam is for high rpm (as in 6000 to 9000 ) race only.

I can't see how you only lost 1 ft lb of torque unless the loss was masked by the lean condition.

2- bigger cam means more air means more fuel yet you said you pulled fuel out. :?

 

Thanks for taking the time to get results, especially since you will be swapping it out to replace with something else down the road.

Oh and welcome to the club. I'm happy your car is a blast to drive. Its the perfect time of the year for turbo cars!

[chiplee]

Some of that power increase can be due to running 13.5 AFR. Thats a little lean to be running at 15+ psi.

 

I'm really confused with your results. They contradict everything about that cam.

1- Schneider claims that cam is for high rpm (as in 6000 to 9000 ) race only.

I can't see how you only lost 1 ft lb of torque unless the loss was masked by the lean condition.

2- bigger cam means more air means more fuel yet you said you pulled fuel out. :?

 

Thanks for taking the time to get results, especially since you will be swapping it out to replace with something else down the road.

Oh and welcome to the club. I'm happy your car is a blast to drive. Its the perfect time of the year for turbo cars!

 

bigger cam means valves open longer, means less injector pulse width required to get ample fuel into cylinder. I was confused on that one too at first but Shelby cleared it up for me.

 

As for the lean condition. I know it's hard to tell from that cell phone pic but it is the leanest run that made the most power. The way you can tell is that it's also the run where we got off the throttle because it was going lean. I consider that run the best comparison with the stock cam though because the run with the stock cam went almost 13:1 also. If we compare to run 7 instead, that a/f ration is closer to 12.5:1 average. Not sure which one you guys think is a better comparison but I just called the shop again to get them to send me the files like they said they would saturday so when I get them I'll post a good clear picture like the graph for the stocker and you can pick it apart all you want.

 

oh and heefner, your confusion on the powerband issue could probably be explained a little bit by degreeing, or the lack there of. I didn't degree the cam. Really, without knowing up front that all three cams are degreed exactly to spec, these results will always be wishy washy at best.

[Chad]

What Heefner is getting at is lean = more HP. Lots of racers that don't care about the time or $$$$ of rebuilding will run thier motors lean because it's free HP.

 

the guy who has the full body quest that ran 9.5's in the 1/4 told me he ran his at 13.5+ because it made so much mroe power. It was also trickey to tune though, and it didn't always last. You can get maybe 10% more power at 13.5:1 vs 11:1, it's just that 11:1 isnt' likelty to detonate.

 

also, not to start a debate, but how does a longer duration and higher lift correlate to shorter injector DC? If it's injesting more air, wont' it need more fuel? If the valve is open more time and open higher, it can't help but to consume more air at a given maniofld pressure.

 

the time an injector is open direclty relates to the amount of fuel that it flows. reducing one reduces the other. unless you increase the baseline fuel pressure, you are just leaning it out.

[chiplee]

I understood exactly what he was getting at, and told him that the stock cam 298/380 pull also ran lean so I compared those two pulls to keep the results as "variable free" as possible. I was working under the assumption that he was attributing the HP gain in the 292 dyno pull to a lean condition more than to the cam itself. I was pointing out that that might be an inaccurate assumption considering the fact that the stock cam was also rather lean when I made the pass with which we are comparing the 292.

[chiplee]

oh and no, chad and heefner you are both wrong. bigger cams take less fuel, smaller cams take more fuel, when nothing else changes.

 

edit: let me re-phrase that. either you two are wrong, or shelby is wrong. I'd really like to know which though. Chad and Heefner, what you're saying used to seem logical to me too, but this is what shelby has said about it in multiple threads to members who "upgraded" or upsized their cams and couldn't figure out why their cars wouldn't run right. This particular person he's talking to happened to have installed a 292. In that thread monty apparently also agreed with the two of you. I'm inclined to agree with shelby and think the 4 of us just have to live with the fact that he knows more than we do.

 

long duration cam's hold the intake open a lot longer,, if your fuel map was tune'd for a stock cam,,your now geting way more fuel then you need , your gona need to remap the entire fuel curve (save your old map incase you ever go back to the stock cam )

[Chad]

stock cam 298/380 pull also ran lean so I compared those two pulls to keep the results as "variable free" as possible.

 

I missed that connection. if they were both similarly lean, then all the gains are in the cam.

 

On the injector duty cycle thing, it may be some other cause that nessesitated leaning a map down for a new larger cam. Emperical data is always better than theory, and I trust that above all. However, the conclusions drawn from emperical data can be inaccurate.

 

It may be that because the motor had to work harder to push air though the motor with a stock cam, it needed more fuel to maintain power and propper combustin to acchieve a given task. With a new cam, the whole combustion dynamic has changed, the motor is now a more efficent pump and it probalby takes less energy to opperate. If it takes less energy to opperate, it will require less air, and thus less fuel to do a given task.

 

As you know, it's all about improving efficency with turbo motors.

 

Perhaps because the motor is more efficent, but because the boost has not changed, there is no need for added fuel, yet the power output has increased. This is a good example of an efficency change netting new power, not from a manifold pressure increase or mass air change (upping the boost or using a larger turbo) creating new power.

 

Simple physics, increasing efficency = more power, with a given work/energy applied. thus if you increase the efficency, you need less work/energy (fuel) to do the same work (HP output).

 

If you increase efficency enough, you can acchieve more power with similar or perhaps still less work/energy.

 

It's an interesting observation...

[chiplee]

I should say that bigger cams take shorter injector pulses to get the right amount of fuel into the combustion chambers, and that overall YES bigger cams make the engine require more fuel. I'm confusing the matter by saying that bigger cams take "less fuel" than smaller cams. Clearly they take more fuel, but what I'm getting at is that the injectors don't have to fire as long to get the necessary fuel into the chambers since the intake valves stay open longer. Don't forget how much fuel is lost on batch fired systems. Whether what I'm talking about is true of sequentially fired ECU's I don't know, but I'd love to hear someone smart talk about it. I suspect it would work the same way, shorter pulses for bigger cams.

 

I follow what you're saying but I really think it boils down to the simple fact that the intake valve is open longer, so the injector doesn't have to spray as long to get the same amount of fuel into the cylinder. In fact if it does spray as long it will put too much fuel in there, so it needs to spray for a shorter period of time. There is certainly more air going in also, but not enough to compensate for the extra fuel. The erroneous assumption, you and I and monty and Heefner were making was that fuel and air intake would increase proportionally if the cam was enlarged. or maybe it was just that the primary effect of a bigger cam would be increased air flow, and that it would result in no increase in fuel intake, resulting in a need to add fuel. That simply is not how it works with this engine at least. I first noticed this when I downgraded from a 292 to a stock cam and had to ADD gobs of fuel to get it to run at all, let alone be safe on boost.

[PDX87Starion]

Just thinking out loud, but shelby's statement seems more logical (to me) for a N/A engine. With forced induction it seems that if your boosting to 20 psi your never going to get more than 20 psi into the engine no matter how long the valve is open. But it would take less effort to get that air in with a big cam resulting in less back pressure from the tubine. ??

[chiplee]

Just thinking out loud, but shelby's statement seems more logical (to me) for a N/A engine. With forced induction it seems that if your boosting to 20 psi your never going to get more than 20 psi into the engine no matter how long the valve is open. But it would take less effort to get that air in with a big cam resulting in less back pressure from the tubine. ??

 

I think that inside the combustion chamber there is alot less different about an N/A motor and a forced induction motor than you think. The physics are the same. The motor "sees" compression. It doesn't know if it came from super high static compression pistons, or if it came from a blower force air in. I don't feel like I know enough to talk much more about it though.

[Chad]

the batch fire part doens't make sence to me either, the fuel comes out wether the valve is open or closed. How long the injector is open is the only part that dictates the fuel flow volume. These cars use a manofld refrenced FPR yielding a static fuel pressre realitive manifold pressure.

 

Just because the fuel puddles on the vavle does not mean it doen'st get burnt, it's just less efficent so a little more needs to be injected to get a similar "bang" (power output per cycle). Is that what you guys are saying?

 

the differneces are nelegable at high RPM, the valve is only open about 20% of a full combustin cycle (4 full strokes), if you are running more than 20% DC, you are spraying on a closed valve anyway. I'm pretty sure you are at more than 20% at WOT.

[chiplee]

Why did you only rev to like 4800 but with the stock cam you almost revved to 6?

 

it was getting lean on that run. the rest of the runs I told the tech to get out of it at 5500 figuring his delayed reaction would make it actually be off throttle no later than 6

 

 

It's a bit nerve racking watching someone else flog your car, right?

 

 

Congrats on the car brother.. I wonder what you could do if you could put all the time you wanted in it..

 

it sure is but he was pretty good about it. asked me all kinds of questions and insisted that we make a real low boost pull "on the house, or off the clock" so he could kinda' orient himself to my car.

 

as for the time thing, thanks for the kind words there. I'll have more free time in the next 8 months than I've had in the last 4 years combined so I might be able to spend almost as much time on it as I want to. Should be a great year either way. I've been enjoying the heck out of this break from the operating forces. lifted my 4Runner, got my car over the 300hp hump, and just generally have less stress. Heck I hardly even bite my nails any more, and that's sayin' something.

[chiplee]

the batch fire part doens't make sence to me either, the fuel comes out wether the valve is open or closed. How long the injector is open is the only part that dictates the fuel flow volume. These cars use a manofld refrenced FPR yielding a static fuel pressre realitive manifold pressure.

 

Just because the fuel puddles on the vavle does not mean it doen'st get burnt, it's just less efficent so a little more needs to be injected to get a similar "bang" (power output per cycle). Is that what you guys are saying?

 

the differneces are nelegable at high RPM, the valve is only open about 20% of a full combustin cycle (4 full strokes), if you are running more than 20% DC, you are spraying on a closed valve anyway. I'm pretty sure you are at more than 20% at WOT.

 

keep the ideas comin' chad, I really do just want to understand exactly what happens. All I have to go on is the fact that after switching form a 292 to a stock cam I didn't have NEARLY enough fuel for it to even idle.

[chiplee]

Ok, maybe this graph is the better one to compare the stocker cam to. I looked closely and the stock cam pull that made 287hp/368tq never quite got to 13:1. This pull with the 292 where it made 312hp/349tq also stays below 13:1 but stays a little farther below so perhaps the numbers will be a little low. You can see in the 13.5:1 run where it made 321hp that it really likes to be leaned out so I'd say adding 5hp and 10ft/lbs, or half the difference, between the 13.5:1 pull and the 12.5:1pull on the 292 cam would be reasonable. That makes the final or best guess cam comparison come out to 30hp addition at the expense of 9ft/lbs of torque, not to mention a much broader power band that starts a smidgen sooner and ends a good bit later. Either way, it made the car feel a WHOLE lot faster for some reason. way more than the numbers seem to indicate. I think most of that feeling is coming from the fact that it's pulling longer.

 

here's the clearer graphs side by side.

 

http://webpages.charter.net/chiplee/fowler.JPG

http://webpages.charter.net/chiplee/stock%20cam.JPG

[heefner]

Thanks for clearing up you reasoning on the lean dyno comparison, I wasn't aware that the previous pulls were also of the same 13.1 AFR.

I know my car likes it lean up to about 13 psi then I go 12.5 and lower.

I'm a little confused. I thought I read that the only mod that was made was the cam. I'm assuming you did not tune anything, having said that, is it true to say your car ran lean after the cam swap. If it is then I'm still not buying in to a bigger cam requires less fuel theory.

After my rebuild this spring I put a stock cam back in to replace the old 284. I did have to add much more fuel but I also replaced the stock ported head with a new marnel ported head. I was attributing the added fuel to the better flowing head. Maybe Shelby does have a point.

[PDX87Starion]

Great info!

 

Yeah instead of the torque peaking at 3600 then going down (on the stock cam), the 292 "peaks" at 3500, holds, and then climbs up to the "summit" at 4500. :wink:

 

Thats probably what you are feeling in the but dyno.

 

What ever is going on, your engine deffinetly has the mods to support a big cam. I just dont want someone to think they can pop his cam in their mostly stock T/B motor and expect big gains. It seems like a lot of newbs think that a cam change (to the biggest one available) is one of the first mods they need to do, when in reallity it should be one of the last.

 

Looking forward to seeing results of the next cam, and then results from final tuning and tweaking.

[chiplee]

did someone pull those graphs down?

 

anyway, no Heefner I had to retune. I reverted to an old map; one where I had used a different 292 cam, smaller turbo and ported head. I just figured it was closer because it was the map that was in the ECU when I put a stock cam in for break in on the new motor. This is the map that was way too lean for the stock cam, but rich with a 292. It was too lean for this 292 but this is a Magna M6 head, chad's neader, and 06H sy/ty hot side. There are no mechanical variables between this cam and the stock cam but there are software variables. I tried to get a pull with the 292 that was as close as possible to the a/f ratio I saw with the stock cam. That was going to require tuning, and that tuning involved taking out fuel.

[Shelby]

man i can't articulate well enought to get into this very far all i can say is learn'd from my own maping of the Hawk fuel maps with a stock cam and a 284 , and i found just as Chip did, going to a biger cam i had to reduce fuel , and later when i went back to a stock cam i had to add fuel to the same map

lots of things come into play when you try and figure out exactly what cams a cam swap made or didn't , the turbo size of ic pieing , amount

of boost , being run, cfm's and they are diff from one car to another ,

same goes for inj size i was runing 700cc's i was told ,i can't prove that one way or another , whats the cars fuel pressure i was runing 56-58 lb , fuel line size it all has a part to play

Chips cam may be slightly late that'd explain the low end gain , i can say i lost low end power and responce with the 284 but it made up for it in a big way on the upper end , it was then i install'd the 3:90s , and the loss was barely noticeable

 

the point about how long the inj sprays vers the time the valve is actualy open may hold the key as to why we found this , it could be that the longer valve open time alow'd more of the inj spray to actualy enter the cyl , where the shorter opening time cause'd more fuel to puddle in the intake , and as we all know wet intakes do not mean a good air fuel mix

 

look at it like this if the longer duration didn't alow for more air fuel to enter,, then the installing of a larger cam would NOT increase the HP out put , one reason you have more air /fuel in the cyl is the the air is push'd into the cyl for a greater part of it's travel , thus alowing for a greater volume even at the same psi

 

a 292. or 284 is not a huge cam , in the na world we ran much larger cams 320 duration and over but suck an over lap would alow for a great part of the turbo air to go right out the exh unless your at some very high rpms

[PDX87Starion]

look at it like this if the longer duration didn't alow for more air fuel to enter,, then the installing of a larger cam would NOT increase the HP out put , one reason you have more air /fuel in the cyl is the the air is push'd into the cyl for a greater part of it's travel , thus alowing for a greater volume even at the same psi

 

I think this part needs more discussion.

 

You can have a HP increase without changing the amount of air/fuel by moving where the torque curve is. Same a retarding a cam to gain more top HP at the same time loosing some low end torque.

 

I dont see how valve durration effects the amount of air or psi unless the cylinder never equals the pressure in the intake.

 

The amount of air in a confined space is measured in PSI (pounds per square inch) the volume is the size of that confined space.

The only way that having the valve open longer would result in more air going in at a set PSI, is if the stock cam is preventing the full PSI of air from equalising the pressure as the piston travels down. Because when the cylinder if full (lets say 20psi) after the air rushes in no more air is going in, no more that 20 psi. 20 psi is the amount of air for that volume of space.

 

So basically what I am saying is 20psi is 20psi regardless of how long the valve is open, but it takes less energy to push that same amount of air in with the longer duration higher lift cam.

 

This is why it makes perfect sense with a NA engine because the amount of air is determined by how much can be sucked through in the given time and opening of the valve. But with pressure as soon as both sides (of the valve) equalise at the given psi no more air (per square inch is going in) and as the piston travels down the air flows in but stays at the given PSI.

 

Or, is it that regardless of the psi there is a pressure drop in the cylinder as the cylinder gos down because the air cant be pushed in fast enough?

 

thoughts?

[chiplee]

you guys figure it out quick I'm installing the roller cam right now.