Thus far I have decided on:

2056cc with around 8.5 compression

44mm intake and 38mm exhaust valves on lightly ported 2.0 heads (in progress)

44mm IDF webers or 40mm depending on more feedback (though leaning 44s).

Custom exhaust with 1.625" primary tubes.

I want to be able to rev to 6k maybe 6.5k max RPM

I have tentatively decided on the Web Cam 494 grind camshaft with specs below:

--------------------------------------------------------------------------------
Web Cam
Part #: 00-682
Grind: 494

--------------------------------------------------------------------------------


----------------------------Intake ----- Exhaust
Valve Lash (Inch):-------.006 ------ .006
Valve Lift (Inch):---------0.465 ------0.465
Valve Lift (mm): ---------11.81 ------ 11.81
Advertised Duration:-----280° --------280°
Duration @ 0.050":........244° ---------244°
Lobe Center:.................108° ---------108°

So now the question:

Using 44mm and 38mm valves, standard 1.3 ratio rockers with a 494 cam, what is the RPM limit using standard 'single' HD springs?

My only concern with Dual Springs is the added stress on the rocker shaft studs that are in 'old' aluminum heads. I would like to run Single springs unless there is no way they will hold up.

What do you guys think?

If it were me I'd shoot for 9:1 compression and run premium fuel. Compression is an easy way to get power, and a 2056 loves 9:1 compression with carbs and that cam. Dunno what the rev range would be with single HD springs. I assume that HD is stiffer then stock?

Zach

I don't think it's going to gain anything from revving that high as horsepower drops off after 5500. I have a 2056 with 9:1 compression and dJet and heavy springs and retainers. It just beefs up the valve train a little.

TQ magic RPM to remember is 5250 and of course it's been hashed a million times over, TQ=Acceleration, HP=Top Speed (most of the time).

Without stabbing gabs of financial resources in a T-4 engine, reving it much past 5000rpms won't do much becuase of the law of diminishing return.

Use to be higher comp|ratio was the cheap and easy way to get that TQ number up. Gas today doesn't really support it without knock sensors etc.



People are giving you sound advice.

When I go through mine, it'll probably be 9:1, Jakes cam kit for FI and mildy cleaned up ports on the heads. I figure with my L-Jet (Gonna probably have to get those 187cc injectors), I'd be turn'in 120hp and 130tq? Something like that?

With the right cam, etc. there is plenty of power to be had above 5000 rpm, and it doesn't necessarily require gobs of cash.
My dd currently has a 1.7L that happily revs to at least 6200rpm and makes excellent power up there.

Another engine I have for my race car revs to 6800 and uses HD single springs.
However, it has lighter than stock valves and ceramic lifters to lighten the valvetrain.

There's nothing magical about 5250. Its about a simple mathematical relationship.
An engine's torque curve and horsepower curve always cross at that rpm (when the y axis units are the same). In other words, torque in lb-ft at 5250 rpm equals HP at 5250 rpm, always.
It doesn't have anything to do with the rpm that peak torque or HP occurs at with a particular engine.

Thanks for all the responses ! Though more are certainly welcome !!!!!!!!!!!!!!!!!!!!!!!!!!!!
Thanks for the heads up! I will look into what I need to do to get 9:1 without custom pistons. Yeah the single HD springs are supposed to be a tad stiffer than stock. The reason I am even concerned about my valve springs is because the 44/38 valves are a little bigger than standard 2.0 and thus a little heavier.


Thanks! Though the 494 cam has a little more duration and lift than a stock D-jet cam and should extend the RPM TQ range a little further. Also when running dual carbs the intake runners are a little shorter, which is also conducive to raising the TQ to a slightly higher RPM.


I do like the 9:1 compression idea and will try to get there without spending too much . Jake's cam kits look great, though I could not find any info on the lift/duration/overlap specs of his cam kits.
Absolutely correct! That 5252 number is how HP is determined from torque

TQ x RPM / 5252 = HP

I want to stay under 6.5k RPM most likely will stay just under 6k RPM, which is why I chose a semi modest overlap cam (280°) ....... I know the 86a web cam (290°) will keep pulling beyond what single HD springs could handle and actually further than I care to take my little motor

According to your race motor (6800RPM) it looks like 6k RPM should be do-able with single HD springs on my motor !! I will also try to lighten the valve-train where possible without weakening it . Thank you for sharing your 'first hand' experience on the RPM ranges of your motors !!!

The web 494 is 288*@ .020, the numbers on that cam have been incorrect from Web for YEARS.

The 494 straight pattern cam with 8.8:1 and 44X36 valves is done making power at 6K unless the heads have decent sized ports.

Also th standard 44mm intake valve is fairly heavy, single springs probably aren't going to control it past 6500 RPM without lofting..

The ramp rate of the 494 is greater than that of an 86A and thats hardder on springs, valve springs and etc.. If my memory serves me correct Chric used the 86A with his single springs.

Do more homework, the 494 is a good cam, but the desires that you have aren't exactly what the characteristics of this cam generally fill. I probably have 200 engines running the Web 494 and probably 200 more with a hybrid dervative of that profile. I drove my car 160,000 miles with one of those installed and it had 44X36 valves..

Thanks for chimming in Snake Oil! More than likely I will stay just under 6k RPM. I just want to know that my larger/heavier valves are not gonna kiss my pistons and or slam on the seats with single HD springs. I have no other issue with dual valve springs other than the increased tension being put onto the factory rockershaft studs.

True, the shorter duration and higher lift of the 494 vs the 86a shoots the valve up/down quicker. But the improved bottom end of the 494 sounds kinda nice.

I would love to use the 86a but I am not certain how much bottom end/response it will lose. The increased top end power however, will of course be very welcome .

The car will NOT be used for autocross or short courses but rather on freeway ramps/off ramps, long winding mountain roads and open highways ..... and if the 86a suits that better, I am not against it!!!

Dual springs increase oil temperatures a notable amount and thats due to the friction from the inner and outer springs rubbing together.

Remember, the 494 is really 288@20 not 280 as advertised, so the 86A is very similar. I have master information for each and have also ran them all in the cam doctor.

I have swapped between an 86A and 494 in the same engine, as a straight pattern cam off the shelf the 86A was a better cam all around to include cabin noise and MPG.

The descriptions from the cam grinder mean very little, the cam may or may not respond to the rest of the engine's combination as described.

Cam grinders are not engine builders. Its all in the combo.

I have done more research and still think the Web Cam 494 (288° duration and .465" lift is the way I will be going. If that is too big, then the European Motorworks 'E' cam is just a tad milder (280° duration and .430" lift).

The only reason to go milder is to reduce stress on the valvetrain and I am thinking my larger valves would make up for the flow loss of not using the 494. With either cam scenario, I was encouraged to go with dual valve springs by the machine shop. Not what I wanted to hear but they build and repair a lot more of these little motors than I do.

Tentative math shows I can get pretty close to the target 9:1 compression by playing with cylinder shims/head gaskets thickness or lack thereof and still clear the valve pockets at TDC/overlap by a reasonable margin. Of course the rocker geometry will have to be redone with proper length chromoly push rods.

The biggest gripe I'd have with the 494 is the very loud intake note that you'll end up with when coupled to carbs..

The cam also has a very fast ramp, so ensure you get it ground on the largest base circle possible, else you'll have lifter bore wear and you'll end up with more valvetrain clatter.

Don't spring it to kill it.

You want the 163/86B. Take my word for it, you will love that cam. Run 44s with 32-34mm vents and you will have good bottom end. Make sure the heads can support the valve sizes. You will want 9.5+ on the compression. Have the cam cut on a 104 centerline. Might also look at a +5. You will have to run a dual spring to get the proper revs, but the engine will spin to 7200+ with no problems and good reliability. You might want to look at getting the springs coated, but I don't know if it will help that much. Get a Mallory Dizzy. The header will also help you. Remember the bigger intake will not help you keep the velocity up in the lower revs but it will come on like a raped ape up high. I would leave the 42 in there and put a good valve job on it and use nicely contoured valves. Also look at using TI retainers it will help keep the valvetrain safer for the extra rpm. The solid spacer kit is nice but it will need to be tailored to your application otherwise it will make noise at idle. Also Custom pushrods are in your future, as are swivel foot adjusters. This will also call for custom pistons and cylinders. Order Pistons and have RIMCO bore your cylinders to each piston. Also the deck height will probably need to be adjusted. The case could stand a few oiling system mods and those should all be done to help support the rest of the system.

You are probably better off buying a kit from Jake. AS you can see the one little change you propose has affected the whole engine. Everything associated with that system will have to be re-engineered to make that one change work properly. Otherwise you will have a poor running engine. To do it right won't be a cheap affair, but to do it right will pay off in the long run with a strong and durable engine that last for years.



Ok, now that I have created the world's longest sentence...............

My vote is for the 86A. 9.5+ comp.
Shimmed single HD springs with Ti retainers and 6200 redline. Should be safe to 6500 rpm.

OH brain fade there. Must have been distracted when I was writing that.

Thank you for the info Racer Chris!!! I do like the 86a character and since I will NOT be doing auto-cross, I would much prefer to have top end power in exchange for bottom end grunt.

From what I understand the 86a will do that. The larger valve seats (44 & 38) have already been installed and I have done most of the 'port to seat' matching last night. If you think I can stay with Single HD springs with the heavier valves to 6k without floating, I am all for it !

I am working on getting the most compression as possible with the pistons I have and am fairly confident of about 9:1 ish. Though I will keep working to eek it higher.

If I have to go dual springs than I might as well go to an 86b cam (.500 lift and .300° duration) ... lol

Don't expect the single spring to control the heavy steel intake valve. Made that mistake. It floats the valves at 5800 rpm. I would look hard at the cam I listed, if nothing else, advance the cam to move the power band down to where you want to use it. You would however be surprised how quickly 6K will come up. Its nice to have that extra power band. Go with the 163 86B, it is the best of both worlds.

For the revs you outlined the 42's would have been the better choice. For the limited revs that single springs will control the 44's are to much valve. You will have much fuel seperation in the area beneath the valve at anything but high revs. At cruising speed the fall out will be severe. Meaning the engine will be harder to tune. The 38mm exhaust are bigger than is required until large displacements and/or high revs are the order.

As Jake stated in an earlier post the 494 has a fast ramp. I have a pair of heads in the shop right now that have 44's and dual springs that were installed on a 494 cam. The cam shows evidence of valve loft, despite the owners insistence that he didn't turn it more than 6500.

Hope it works out for you, but your combo is already compromised by your valve choice. You could always up the compression, install dual springs and keep it turning. That would better suit the valve choice you have made.

Thanks for the note Brett. I think you convinced me into going with dual springs, it will indeed give me more cam profile options. I will also make sure the valve component travel is configured to accommodate a higher lift, just in case

As I have mentioned before, I would much prefer to gain higher RPM power over lower RPM grunt. So dual springs falls in line with that direction

Ham thanks for the info. Though with all due respect, fuel separation 'at cruise' is caused by more than just large valves or slow port velocities. Another big contributor is a long overlap cam, which does not create a good intake manifold vacuum 'at cruise speeds'. Higher vacuum vaporizes fuel or any liquid for that matter. That is why boiling points of liquids are progressively lower at higher altitudes.

Another issue that high overlap cams have at 'part throttle', is the exhaust gasses are slowed a bit. This is due to the higher pressure exhaust making its way towards the intake during an extended overlap period.

Thanks for posting guys !!!! Please continue to post any experience with the 2056 in various carb/high performance configurations

Yep. That is correct. And that is why a cam that reads like a big cam on a 2056 will read like a small cam on a 2550.

The cam options that have been bandied about on this thread are long enough and have enough overlap for a 2056 to have sluggish port velocity in the vicinity of the intake valves at part throttle. That's why I mentioned bumping the compression and turning it up. And since it sounds like you want this baby to run at higher revs that should work for you. Those valve sizes will really breath a 2056 and support some serious revs! But you will need springs for it.

Looking at the other extreme, a 2056 with 1.7 heads prepped with 40mm intakes and 34mm ex would make a great bottom-end engine and cruise great with good mileage. Would get by with single springs as it wouldn't have enough top-end power to need duals.

That's one of the things I love about the T4 there are many options available to ensure that everyone gets what they want.

So the engine theme is settled !

Looks like I will be going with bigger cam, dual springs, higher compression and higher revs !!! I may have to make custom pistons to go above 9:1. But if it will give me a little fire breathing monster at higher revs, it will be worth it!!

I was looking at the 163/86B split lift/duration recommended by Brett and the shorter intake duration should improve the bottom end over the straight 86b. I will take more measurements and see if I can hit a solid 'static' 9.5:1 compression with my exisitng pistons.

KB 96mm flat topped pistons. You do not need to move the cylinders much at all to jump the compression.

Zach

Yeah flat top KB 96mm pistons with a .040 piston to deck clearance will work well. Cut the heads down to shrink the combustion chambers down. The bigger the cam the more compression you can run (within reason). Shoot for 9.5 or higher to make the cam really work right. It will give good bottom end if done right. Since it is a street car go with the smaller venturies on the carb to help keep the velocity up. What you gain in the midrange will greatly offset the minuscule loss on the top end. The system has to be carefully considered.

Makes sense !! I have a a nice flat top set with very shallow valve reliefs. I will measure them to see how manys CCs the valve pockets are. I will probably not use a head gasket and slightly cut the heads to reduce chamber volume. Of course keeping a nominal deck height to prevent any interference.

I believe the 2.0 combustion chamber is about 60cc. Using that as a reference and using rudimentary math, if I get it down to 55cc with fly-cutting, I will get a tad bit higher than 9:1. Higher compression calculations and CC measurements will be worked out more accurately after I install the valves. However I am getting a set of 44mm IDF webers ASAP !!!!

Using dual valve springs, 44mm intake/38mm exhaust valves, higher RPM power 'target' and much discussion on this thread (thanks guys!!!) ....... thus far my cam choices are now as follows:

web

86b ---------- .500" lift and 300° duration

163/86b ----- .500" lift and 284°/300° duration (split cam)

163 ---------- .500" lift and 284° duration

EMW

T-4H --------- .488" lift and 286° duration

T-4II --------- .475" lift and 281° duration

T-4J ---------- .500" lift and 307° duration

mmm great info

Please, don't just set deck height at .040 and call it a day.

measure the CC of your heads and calculate what you WANT your height to be based on the target compression ratio.

My heads were 55 CC. If I had assumed 60CC my compression would have gone very much off from my desired 9:1.

Find a web based CR calc, and plug in your metrics (I actually have a sweet little app on my iPhone for it). Don't guess on your deck height and CR, KNOW it.

Zach

The J grind cam makes for an engine that isn't very streetable in my opinion.
I had a 2.2L short stroke engine with one that made awesome power to over 7K rpm but had trouble leaving a stop light unless I revved it to 4500 and dumped the clutch. (The 48mm intake valves had something to do with that I suppose. )

Most un-cut 2.0 914 heads fall in the 58-60cc range.

A .010" flycut removes ~ 1.4cc's.

What ever you do keep the piston to deck height to .040 or slightly less. .040 is a safe number that I would go no higher than. You can run lower but I don't advise that unless you have very tight control over you piston to wall clearance. The KB 96mm pistons can run pretty tight clearances because they don't tend to grow like the Forged pistons. Great for ring life and noise. The higher the deck height you run the less efficient the chamber will be.You should also check the combustion chamber fit to the cylinders and make sure you have no sharp edges overlapping into the cylinders. Don't use headgaskets, throw them away now.

I would cut the heads down to 55 or less. That will help the compression. You need as much compression as you can get. You can't get too much with the flat top pistons. True the tops and bottoms of the cylinders on a lathe and set your deck heights with the small shims under the bottom of the cylinder. Also true the block deck as well. You want the cylinder as straight as possible.

Are you doing port work?

Check on the deck height, cylinder true check and no head gaskets . I have already marked the mating interface of the cylinder to head and have removed the offending material. The flow path to the valves is smooth and obstruction free. I have even lightly 'unshrouded' the valves to improve flow on the valve/head area near the cylinder walls. I did not remove too much, as I need some of that for compression purposes . I will also radius the bottom edge of the exhaust valves to minimise any potential 'hot spots' and to improve flow around the valve bottom and into the exhaust port.


I am doing very modest port work because I like to keep port velocities on the higher side. This being a smaller 2056 motor, it shouldn't need huge ports. Mostly getting rid of casting imperfections and leaving a nice 'sanded' finish to create tiny surface vortices to improve fuel atomisation. Also the intake manifolds inherent 'funnel like' taper should accelerate the A/F mixture nicely into the port. The manifolds will get the same surface treatment and port matching when I get them.


The stock 2.0 intake port diameters are around 35mm and after the current work should measure just under 36mm. Which is roughly a 5-6% increase in cross-sectional flow area. I may go bigger but this is where I am at thus far, more number crunching regarding port size will be done taking various cam profiles and RPM ranges into account. Removing material is easier than putting it back on

true the cylinders on a lathe? I won't say don't do it, but I wouldn't.

I don't really do not want to discuss 'methods' on this thread, as everyone has their own way of doing things and it drives many threads 'off topic'. A lathe is more than likely an extreme case and I have never done it. However there are numerous ways to remove imperfections. The cylinders are probably not too bad and may only need lapping at worst .

some people have access to really expensive tools too! I know this well, particularly after reading this forum for a few years.

I'm constantly amazed at the stuff that is created and posted here. Bookmarked and looking forward to hearing how your build goes

Thanks for your input, I agree, there is indeed a wide spectrum of experience, knowledge, abilities and machine capabilities on this forum ! That is why I queried for some first hand experience on here.

I will measure everything I can, to avoid common pitfalls. I wish I had a bigger budget for this build, but the dough designated for this project has to be spread across the GT flare install, body work, paint, brakes, suspension, gearbox, electrical, wheels/tires, interior and finally this little engine. With the current budget, there is no way this project is even gonna come close to what I would like to do on this little car, but that is not gonna stop me from trying to get a decent result!!!

Since I am going with dual springs, the 86a is still in the running as a possible cam, depending on how it would fit into this configuration and its RPM/torque limits.

If you do an 86A do an 86A/86A+5 or +10 on the exhaust side.

If you have a mandrel that can locate off the center bore of the cylinder and are using a the chinese cylinders, you most definitely need to verify the cylinder tops and bottoms are square.

I did my cylinders and was impressed with how crooked they were and how far off each cylinder was compared to the rest for deck height. I used some custom shims on the bottom of the cylinders to set the deck height to the proper clearance for my specifications. Are you having RIMCO bore your cylinders? They can perform this operation for only a few bucks more.

How is the +5 or +10 done? Do they just grind .005" or .010" material off the 'base circle' opposite the lobe?

I will check the cylinders on a 96mm rotary mandrel with some dial indicators before I start cutting material off the heads, as this will affect my deck height should the cylinders need serious truing.

Don't judge those cams simply by their .020 and .050 numbers.. To really understand the numbers you need to see what the duration is at .200-.350" lift.

If you consider those numbers some cams magically appear much larger than they used to when you just looked at the advertised numbers. Choosing a cam from just those numbers isn't illustrating the big picture.

FYI- The cam in Len's FP engine that spins 8,500 RPM is actually smaller than all but one of the cams you mentioned if one looks at onl the advertised numbers, thats in a full race engine with 13:1 CR.

The difference is that cam is HUGE between .175-.410" lift. Lots goes into camshaft selection, you can't really make the best choice until you have actual flow numbers from the heads.

Amen! I've been trying to help folks understand that for years, but sometimes (not always) it's like talking to Nigel from Spinal Tap. "but this one goes up to 11!"



Yep. That's why I have spent countless hours on the flow bench and Jake has spent countless hours pouring over the flow data and testing cams on the dyno and the street and the track.

And I'll take Jakes statement one step further. You can't accurately port a head until you have base-line data. Years of experience make it possible to sight out obvious problem areas for improvement, but until you know the ex/in flow ratio an educated approach is not possible. And screwing-up the flow ratio bad enough may dictate the need for a special cam grind. Getting off just a few % can lead to an engine with performance characteristics different from that desired.
The intended use for the vehicle the engine is going in is the single biggest factor I consider when choosing a flow ratio. It is very important!

No shameless plug for our businesses intended there, just some info.

Great analogy!

I was trying not to confuse the OP with ramp rates, and flank characteristics, it is sometimes hard enough to explain to the average person duration and lobe separation. Jake and Len are spot on with the characteristics of camshafts.

Head work will radically affect camshaft requirements. Not really sure what your plans and experience with the T4 head is but be careful just hogging out the ports.

It might pay to offer Len a little something to pick his brain. Could be money well spent.

Thanks for the kind words Brett.

I will offer this insight for free. To maintain the optimal port balance for a typical high performance street engine if I spend 10 minutes in the exhaust port I will spend between 30-40 minutes in the intake port.

...The only proper way to compair a camshafts, lift and duration, is to create a lift and duration table for each camshaft you are considering....And before you can do that , properly, ...you must decide at what point you are going to Begin to take measurements...And to do That properly, you must decide , (use a standard) when air flow actually begins to enter the combustion chamber. And to be able to get a handle on that you must know what your valve lash is going to be , and what it will be when the engine is hot and running.(total Lash)....One way to get a handle on all this is to become the engine you are building, to think about how you want air flow (into and out of yourself) to happen and when. And efficent, and effective. It is very easy to overcam( Duration) an engine. it is very easy to over port or over valve an engine. These are easy mistakes that are done all the time. relieing or beliving in "head flow" numbers as the holey grail of head work is fiction to the extent that "head flow" can never replicate the actual engines air flow in operation...Every engine, in my opinion, should use dual valve springs.....all this as food for thought......from murray.

lol none of the information anyone has posted is confusing. What is a little strange, is why anyone would think it would be

Lobe separation, lift, duration, ramp curves/rates or lack of (straight slope) etc. are easily described as a sine wave (different cam specs create a different shape). Intake and exhaust lobes each create their own wave ....... overlaying these waves on their respective time reference determines where and how much they intersect/interact to describe overlap and lift in relation to TDC and piston travel. How these factors interact with each other in theory on paper, is usually very different than in practice, as practice generally introduces new unfactored variables.

This thread was started to query for first hand experience with various cam profiles vs carbed 914 engine configurations. So if you want to share your experience, it is much appreciated.

Good stuff, I agree !!

I saw something a while back about the port diameter in relation to valve dimension and can't remember off the top of my head what it was. You may run into issues with the 44mm intake valve and the total port dimension ratio being out of sync. I wish I could remember where I read that, since I have been playing with boosted 4 valve heads lately I don't worry so much about the 2 valve stuff like I used to.

On my engine I ran 42mm/36 2.0 914 heads. The heads had been cut down quite a bit, but I also went a little over board opening up the chambers around the valves. I paid for that with a little less compression than I wanted. It was 8.9:1. I also went a little hog wild on the intake ports and thus lost some velocity. Lesson learned. The engine was a little soggy way down low, but I worked around it. But above 3500 it pulled like a raped ape all the way to 7500. Engine made 118hp at the wheels through stock heat exchangers. I think with more compression and decent headers it could have easily done 130 at the wheels. The engine ran great. Also the lightweight flywheel I had tended to affect drivability, it was an 11lb flywheel (On a bathroom scale). (I suspect it was lighter than that)

I was running 44idfs with 36mm chokes and a modified 1.8 dizzy. If I had stuck with the T4 engine I would have gone down to 34s and swapped to a Mallory. That should have made a big difference in the mid range without affecting top end. The gearbox had an S and X 4th and 5th. car pulled like crazy from 70-127. I pulled on a Supra (NA) from 90-127.

Of course a 2270 is a cheap upgrade in the grand scheme of things.


What are you using for your valves? What angles and seat widths are you contemplating? You will find some low lift flow with a nice 30deg back cut on the underside of the intake valve. Some people have found benefit from a 15+degree cut on the face of the exhaust valve but I also wonder if on our engines it causes the valve edge to run hot. I assume you are just running stainless aftermarket replacement valves with stockish dimensions. Not a nice tuliped head valve right?

RAT 9500 cam & lifter kit. Worth every penny.

That sounds about right .

The tiny budget rules my options at this point, so the extra $1500 or so to go 2275, is not gonna happen in this iteration.

The valves are very nicely deburred stainless, with 'tulips' being their first, last and middle names

Sounds good , though without any specs or ball park, I will not know how to set up the heads .......... I do not know why no data is listed with those type 4 store cams ............ that is why I am looking at cams that have 'some' numbers published ......... at absolute minimum, I would need to know the peak lift to make sure my retainers are not gonna kiss the guides, also duration to have an idea where the valves are gonna be with respect to the pistons during overlap/TDC. Personally, I do NOT like the 'slide your money under the door' approach to buying anything. I like setting my own stuff up, so I can take the credit when it blows up

Often times big cams, big ports and big valves make LESS power, or they'll create a power band thats virtually worthless for the intended application.

"advertised numbers" for cams and their statements of RPM range are generally worthless. Thats why we have no one line statements about what any camshaft does to the engine, doing so is often times going to send someone down the wrong path.

There have been times here when we've changed cams in the same engine 10 times in a single month to see the effects of those grinds. Hell one of my VW Bus combinations took 14 camshaft deviations to find the right profile and that sometimes was simply a change in lobe separation, other times we just added 2 degrees to the exhaust side of the cam. small changes= large differences in lots of situations.

That said, the camshaft is the LAST component that you buy, AFTER you settle on exact CR and exact port work and have those values.

This thread has turned into a circus of sorts, but I am getting useable info on some of the posts . I thank those of you who posted in good faith !!!


NOW we are talking!! Len's cam sounds like a quick ramp rate and stays high for a longer period . An increased area between the start of the ramp and full lift will indeed feed an engine at higher RPMs, than a slower ramp rate or narrow lobe. Trouble is, there is no way for me to know what I am getting short of buying a ton of cams and measuring them. Which I may have to do, if I do not find what I need.

I may be new to the forum but I am not new to performance engines. One of my passions is in intake and exhaust system design. I have successfully increased HP on many exisiting performance engines (of other makes), for a very long time.

I understand many people build type 4s for autocross and want 'torque' ASAP. My motor will NOT be doing ANY short courses.

FYI one of my other cars does not reach peak torque till 4.5-5k RPM and peak HP till well over 8k RPM, with redline a hair under 9k RPM. It suits my tastes perfectly .

I understand your methodology, but I usually massage the heads, compression, intake and exhaust to match a cam's characteristics/potential first, as those parts are far easier to remove, replace or modify than a camshaft.

I am interested in cam specs similar to Len's, unless it is some sort of a secret or personal custom grind. Then I respect his accomplishment and will find my own way, not a big deal. Thanks for the info so far.

One thing you'll learn is that the design of THIS engine is much different than other engines. I work with people who misconfigure these engines horribly and they have experience just like yours, with other engines.
Just be foreqwarned that your previous experience is probably best left aside, you have to start from scratch if you want to be successful.



Guess what, thats what I've been doing from day one. I have cam doctor plots for EVERY one of my 65 cam grinds. More importantly I have dyno graphs of each cam (and all its derivatives of split duration, lobe separation/ etc) from all my popular displacements with all of our RS and LE head offerings coupled to them. and CR from 8:1 up to 13.75:1. I just finished sorting those files this week, they tally over 8,000 plots from 1997 to present. Thats not counting the hard drive full that I lost in 1999 to a lightning strike. Pouring over the files and overlaying the average power information all derived on the same two engine dynos and chassis dyno really tells the tale. Having driven all of those combinations is the other pricless bit of data.

Lens cam is a secret weapon, actually both of them are. I was just using that cam as an illustration of how headwork and displacement can turn a race cam into a street cam in two different engines.

I have used the cam I designed for Len in a 2270cc engine with a 200CFM intake port and a 75% I/R ratio and the result was a powerband from 3-6K, instead of a powerband from 5-8.5K like Len's race engine. In the 2270 the cam idled like stock at 950 RPM and had a flat torque curve...

Keep doing your homework.... Just realize that the downfall of many TIV engine designers has been treating this engine like something that its not. Understand that now and make wise decisions.

What do you plan and I'll look through my plots for a similar combo and post the charts with their notes.