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you seem quite knowledgeable and experienced, so for you and Jeff (Wreckless)...


re: cams - it is my understanding that the general trend is more lift/less duration for n/a motors and less lift/more duration for turbo motors. is this incorrect?

re: rev limit - it is my understanding that generally, most turbo motors are revved to just beyond where the turbo noses over (no longer holding power). for example, iirc, my rev limit was 9k-9200 with the 8685 that started to nose over around 86-8800.


craig
Hey Craig! :beer:

On cams - More lift is almost always better unless we're getting into component limitations (e.g. spitting shims, beating the shit out of valve seats, valvespring coil bind/valvespring fatigue failure etc) because more lift always equals more flow everywhere. Whereas duration dictates the RPM range in which that combination will make max HP. Generally speaking, more duration = higher RPM. Overlap between intake and exhaust valves is the biggest difference between camshaft choices for NA, turbo, or supercharged engines. NA engines benefit considerably from some overlap especially in higher RPM ranges, giving everyone that lopey cam chop most folks love to hear at idle. This is because the exhaust side is almost always an area of lower pressure so it's a scavenging-effect trick to 'suck' air in through the intake valve.

Turbocharged engines, on the other hand, always have more backpressure than boost pressure. This means that overlap can be detrimental and actually cause exhaust reversion *back* into the cylinder through the exhaust valves. That's an extreme case, but it's easy to over-cam a turbocharged engine to a point where the power curve is moved further to the right, but peak HP is not improved due to turbocharger limitations.

This is also why most camshaft selections for 2JZ's and other turbo engines don't have much if any lope once they're degreed properly. Cam upgrades on turbo engines generally reduce the boost pressure required to make a given whp figure and on most setups (provided the turbo's exhaust housing or turbine isn't profoundly undersized) that also reduces backpressure somewhat (again, so long as the turbine housing isn't undersized) and with reduced backpressure we have reduced EGT's. Ideally, between cams and turbine housing selection one wants to get the backpressure as close to 1:1 with boost pressure as possible, and the optimal RPM band of a given camshaft selection should be matched to a turbo's power range as closely as possible.
Ideally, the engine should be falling off cam at the same time the turbo noses over - this is why GSC and other cam makers are suggesting turbocharger sizing to match the cams involved, not HP level. Similarly, there's only so much one can push the no-overlap game before it's detrimental at very high RPM, so big ass cams like HKS 280's and GSC S3's will have lope no matter what, but that's based on the needs of big ass turbos at high RPM, which are again under the assumption that it's a big ass turbine housing with minimal backpressure.

So with those cams and big turbine housings things are great when in boost, but the off-boost torque response suffers especially in non-vvti cases due to the loss of dynamic compression. With VVTi engines, they can retard the intake cam to increase dynamic compression at low rpm/off boost and vastly improve off-boost torque and driveability. VVTi is really pretty kick ass stuff.
Similarly, we can get away with more static compression if we've got rowdy cams, due to how the advanced intake opening reduces dynamic compression. So an engine combination that had detonation on a given fuel at 18psi with stock cams, may be just fine at 18-19psi with 272's or 280's installed and the same ignition timing values. The same can also be true of turbine housings, if it's detonating with a .68 housing a 1.00 may add lag but also reduce the backpressures enough to run without detonation.
Power is moved to the right with these changes (as well as peak tq in most cases) so we can see the relationship on how moving the powerband to the right reduces peak tq at lower rpm and how that peak tq value can be used to determine what's safe on a given fuel. These days though, with E85 and such - we normally just want to make more HP and that's why the bigger cams and housings get involved.
But on gasoline, playing these games with stock-ish ~8.5:1 static compression with big housings and big turbines with big cams is how Japanese tuners have achieved 800-900hp on their RON 100 (~94-95 octane) pump premium. Such combinations add substantial amounts of lag, but it doesn't really affect the type of highway racing they do with that kind of HP, it's all high-speed roll-ons often starting at 60-70mph and exceeding 160-180mph at times as they haul ass around toll highways that are deserted late at night.
So bigass turbos like the GReddy T88H-38GK with bigass housings on 8.5:1 3.4L's with HKS 280's make sense - less lift on the cams means less valvetrain beating for those long ass high RPM pulls. This is also why Japanese tuning houses were historically obsessed with oil coolers, coolant expansion tanks, etc. Keeping a car alive for 30-45 seconds in a highway pull is one thing, keeping it alive when it's in boost for 20-45 minute blasts at 150+mph at a time is a much different beast.

Supercharged engines are at the opposite extreme, where there's little if any backpressure from the exhaust system but there's a bunch of pressure/air mass coming in the intake side. The benefits of duration for max HP on a given fuel and higher RPM performance are much the same, but ideal cams for superchargers are typically disproportionate on the intake side vs exhaust side, with a lot more duration on the intake side and less on the exhaust side. Too much duration on the exhaust side of the cam, and especially overlap, leads to boost pressure basically being blasted through the cylinder with little beneficial effect. This is why on DOHC engines with superchargers we'll often see the best results with staggered cams with a 272 on the intake and a 264 or 256 on the exhaust. If the desired RPM range dictates more duration, that duration difference tends to stay proportional (280 intake + 272 exhaust, etc) and of course overlap is tuned out completely for lower RPM engines and it's as minimal as possible to match the needs of higher RPM engines.

With NA and supercharged engines, there's a tendency to over-cam the engine just for the sake of the lopey sound, especially on domestics. So it's common for an LS powered F body or 5th gen to have a cam that'd be ideal for a 7-8k rpm build on an otherwise stock LS1/3 that doesn't see past 6k for the most part.
This moves the powerband to the right and affects low end tq, but big V8's have a lot more low end tq to spare before it's detrimental to driveability. We can see the same effect on turbocharged engines, where folks in the past have put HKS 280's in BPU cars and they sounded great and did pick up high RPM power, but the backpressure and turbo limitations show up long before the cam is done making power, so the power was moved excessively to the right and it's likely, even probable, that correctly degreed 264's or similar would make equal if not damn near the same peak HP but without the added lag.
Overcamming supercharged engines, though, just wastes power. The nature of a SC engine will mask the losses quite well so most people don't notice and they think it sounds cool, so they drive on with it. But going to a proper cam profile developed for a SC engine often shows rather impressive gains, regularly in excess of 50-75whp on a 550-650whp car.
I have also seen two different 5th gen Camaros that were virtually identical builds except for camshaft choice - one was a 6-spd whipple + longtubes car and the other was a 6-spd whipple+cam+longtubes car. The cammed car had a rowdy ass cam meant for an NA. After tuning, the car with the stock LS3 cam was barely ~15whp less than the rowdy-cammed car. The cammed car had picked up close to 70whp from the cam prior to the SC install. That is an instance where installing a proper cam for a SC profile would likely pick up ~50-60whp right off the bat.

I've added to this post throughout this morning so hopefully it's cohesive and makes sense.
I would welcome any input, as I don't consider myself a foremost authority on this stuff, and I'd love to learn more from anyone with additional insight/experience in these things.
 

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^^My second nomination for 2018 post of the year.


Ken.
 

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Wreckless guys have been running up to 9300rpm on stock modded pump. I have seen some cars with parts from Velocity Racing Performance on facebook who rev up there. I have been to 8700rpm back on the 3.0L.

For cams. I like high lift but there comes a point when the turbo size needs the duration also and the cam to behave the same way. Its a match.

VVTI helps to about 4500rpm. I think after 4500(around there) the cam zeros out and its like a non vvti. So if you have a turbo thats spooling later and u race in the 5500+ rpm range then vvti wont necessarily help you.
 

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Jeff's post is man-crush material.
 

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The main reason you dont see much development for high RPM 2jz's except for the elite drag crowd is because of how effective the turbo technology and engine management has come these past years. Billet turbos, quick spool valves, vvti and E85 all help produce low end torque and improve spool characteristics. With the current technology you can make big power on the street and have a decent power band. And im sure if you moved the 2jz power band so far to the right you would eventually need to re-gear the vehicle either through transmission or diff options. So in the end the high cost extra engine wear need for a dry sump make it a feasible option only for those chasing that every 1/10th of hp.

Everything you're asking for cam wise is available btw, kelford, titan etc can all make custom cam grinds. but all current options are proven up to various hp/tq levels. if you can make 700-1000hp by 7-8k rpm have decent power under the curve and not have to beat the motor at 9-10k rpm wouldn't you? especially if the car is geared for that power band already?
 

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Discussion Starter #28
That assumes the car is running something other than pump gas so it is able to crank up the boost.

If the car isn't in a competitive racing class and has access to E85 or has methanol injection, it can just crank up the boost. Every other tuning metric becomes irreleivant.

However, what if you are restricted to pump gas? And in a 'street rod' or equivalent, the specs count. A Porsche GT3 street car is not going to be in a competitive race; Porsche sells GT3 race cars for that. MB, Ginetta do also. But owners think about the bits of technology powering them, even though an extra 500cc may have provided more benefits.

I'm coming from short track oval racing where the 3ft difference between having your bumper along side a competitors door or their rear tire is difference between making pass or having to back off. On the short straights that is just a few hp. I'm also familiar with the K24/F22c world.

I've noticed the same pertains to cylinder heads. In oval track racing porting isn't allowed; however it is in the Honda world. There, well tested and developed CNC designs dominate with different designs for different types of racing and different class rules. All though the cylinders are the same size as a K20, the Supra has smaller valves and the cams have much less lift. Yet, the CNC heads seem to esteric take-it-or-leave it, it made 1500+hp on this one time fast drag car, some are hand ported, and enlarging the valves from small to slightly bigger than small is considered a performance mod for 1000+hp.

Let's just say I'm disoriented.

I'm not a drag racer, and even if I was the biggest track around here, Englishtown, just closed. There are no competitive road racing classes for the 2JZ; even when it was raced in Japan it was first with a 4 cylinder and then with a V8. This is a 'street rod', built for enjoyment where racing is confined to wheel dyno.

Is it better to discuss who has the best billet polished pulleys and cam covers rather than camshafts and valve springs? I've noticed that discussions of 'ceramic coatings' are more likely to be paint sealents than coated turbo housings and headers.
 

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That assumes the car is running something other than pump gas so it is able to crank up the boost.

If the car isn't in a competitive racing class and has access to E85 or has methanol injection, it can just crank up the boost. Every other tuning metric becomes irreleivant.

However, what if you are restricted to pump gas? And in a 'street rod' or equivalent, the specs count. A Porsche GT3 street car is not going to be in a competitive race; Porsche sells GT3 race cars for that. MB, Ginetta do also. But owners think about the bits of technology powering them, even though an extra 500cc may have provided more benefits.

I'm coming from short track oval racing where the 3ft difference between having your bumper along side a competitors door or their rear tire is difference between making pass or having to back off. On the short straights that is just a few hp. I'm also familiar with the K24/F22c world.

I've noticed the same pertains to cylinder heads. In oval track racing porting isn't allowed; however it is in the Honda world. There, well tested and developed CNC designs dominate with different designs for different types of racing and different class rules. All though the cylinders are the same size as a K20, the Supra has smaller valves and the cams have much less lift. Yet, the CNC heads seem to esteric take-it-or-leave it, it made 1500+hp on this one time fast drag car, some are hand ported, and enlarging the valves from small to slightly bigger than small is considered a performance mod for 1000+hp.

Let's just say I'm disoriented.

I'm not a drag racer, and even if I was the biggest track around here, Englishtown, just closed. There are no competitive road racing classes for the 2JZ; even when it was raced in Japan it was first with a 4 cylinder and then with a V8. This is a 'street rod', built for enjoyment where racing is confined to wheel dyno.

Is it better to discuss who has the best billet polished pulleys and cam covers rather than camshafts and valve springs? I've noticed that discussions of 'ceramic coatings' are more likely to be paint sealents than coated turbo housings and headers.
There's a lot of motorsport use of the 2JZ-GTE in drifting, and lots of that involves high RPM use for moderate amounts of time. With drifting though it's mostly a game of area under the curve, and they want the biggest possible curve with lots of RPM for the widest range of big power availability. This generally means they spin 3.4L strokers to around 9k with a lot of compression and big ass turbos on race fuel or E85, which is fairly formulaic at this point.

Headwork obviously plays a role in overall performance but the simple fact is that the 2JZ-GTE head is not all that great no matter what you do. If one truly wants to go 'all in' then sure, a head gets a CNC port and 1mm or 2mm oversized valves with all the corresponding work. Generally speaking for most street 1000whp builds, though, stock size valves work just fine because the game has always been "mucho boosto".
Enhancing the cylinder head flow to reduce needed boost pressures is great, but when lots and lots of work might be the difference between 1000whp @ 35psi and 1000whp @ 39psi, the juice is rarely worth the squeeze. Especially with responsive modern turbochargers that are delighted to push air at those kinds of pressure ratios.

If you're restricted to pump gas, the easiest thing is to start following the Japanese strategy of modest static compression, big ass cams, and the biggest and most efficient turbocharger you can stand lag-wise. Headwork is an improvement regardless of the other supporting parts, but most of those parts like big cams and big intake manifolds do a lot more for the $ vs head porting. If we were talking ultra-competitive wheel-to-wheel racing that was restricted by turbocharger, intake manifold, etc - I'm sure we'd see a lot of exploration on what makes the best possible cylinder head combination to get that extra HP where it's possible.
But with so many other variables to play with that can achieve virtually any HP goal one can dream of, there's little incentive.

If it really came down to that kind of game, I'd hit up Arnout and get one of his K-series style billet VVTi 2JZ-GTE heads and let it eat. ~$13k for a head package that is light years better in every possible way to include dual iVTEC style VVT seems to be a much better value than spending $4-7k on a top-shelf CNC program head porting & big valve package that might improve things 20% if you're lucky.

Supra guys were early adopters of Ceramic coating for temperature control. So most of the discussions are been-there-done-that and most big builders have a ceramic coating they like and it's a 'click the box' option for manifolds, turbine housings, downpipes, etc.
 

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Discussion Starter #30
Does that head really exist. I've seem the pictures of a one cylinder segment. I've seen pictures of a two cylinder segment that shows the head has an upper section and a lower section so that cooling could be milled. To have dual VVT and VTEC means custom cams and an unclear VVT mechanism. BMW's? It would need to handle a 6 cylinder 12 lobe cam. I'm guessing a dry sump pump moves to the required level to drive 6 VTEC followers and dual VVT.

However, I've never seen a complete head, read of an engine with the head, or can find the head listed anywhere. As a two piece, there are custom parts that would otherwise be hard to source. What happens when a part is needed in 5 years or 10?

On pump gas a lot of those issues occur in the 600hp-700hp range. But it seems either E85 or water/methanol injection has moved to the stage where adding more boost is always the answer.

Of course, some it begs the question: why hasn't there been an effort to increase valve lift and aggressiveness in general? Why, when doing the valves and a 'pocket porting' anyway, are oversized valves scuffed at? 4Piston has there top road racing head, complete CNC including chambers, oversize valves, their best springs, beryllium exhaust seats, for $3900 with customer's core. And those guys do a lot of testing, make K24s for sprint car racing. As I said, I'm disoriented. Just not used to "more boost" being the answer to every question.

I was thinking of coating piston tops, combustion chambers, valve faces, and exhaust ports. Keeps the head in increasing combustion and reduces heat transfer to the cooling system, sending out the exhaust instead. A sodium cooled exhaust valve would also transfer head from the valve head to the stem to the guide rather than to the valve seat. I had a discussion with Ferrea where they thought it was a bad idea. I'm guessing, in reality it falls into the E85 "more boost" is easier category.
 

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Does that head really exist. I've seem the pictures of a one cylinder segment. I've seen pictures of a two cylinder segment that shows the head has an upper section and a lower section so that cooling could be milled. To have dual VVT and VTEC means custom cams and an unclear VVT mechanism. BMW's? It would need to handle a 6 cylinder 12 lobe cam. I'm guessing a dry sump pump moves to the required level to drive 6 VTEC followers and dual VVT.

However, I've never seen a complete head, read of an engine with the head, or can find the head listed anywhere. As a two piece, there are custom parts that would otherwise be hard to source. What happens when a part is needed in 5 years or 10?

On pump gas a lot of those issues occur in the 600hp-700hp range. But it seems either E85 or water/methanol injection has moved to the stage where adding more boost is always the answer.

Of course, some it begs the question: why hasn't there been an effort to increase valve lift and aggressiveness in general? Why, when doing the valves and a 'pocket porting' anyway, are oversized valves scuffed at? 4Piston has there top road racing head, complete CNC including chambers, oversize valves, their best springs, beryllium exhaust seats, for $3900 with customer's core. And those guys do a lot of testing, make K24s for sprint car racing. As I said, I'm disoriented. Just not used to "more boost" being the answer to every question.

I was thinking of coating piston tops, combustion chambers, valve faces, and exhaust ports. Keeps the head in increasing combustion and reduces heat transfer to the cooling system, sending out the exhaust instead. A sodium cooled exhaust valve would also transfer head from the valve head to the stem to the guide rather than to the valve seat. I had a discussion with Ferrea where they thought it was a bad idea. I'm guessing, in reality it falls into the E85 "more boost" is easier category.
I've seen the proof-of-concept partial head in person, twice. I talked to Arnout at length about it and even with the bottomless pockets of some of the Supra enthusiasts in the mid-east, there's not at lot of interest in such an 'ultimate head'. Long story short, if you put up the money he'll make it exist and to your specs, your choice of intake and exhaust manifold patterns, etc. IIRC all the components including VVT gears were K-motor. Lots of support and easy to replace.

$3900 buys the 'all of it' cyl head porting package, but $3900 can buy a good intake manifold & TB plus bigass cams and matching springs & retainers. Could do all of that plus shimless buckets for the $4500 range, which is money much better spent even if that leaves you with stock valves and ports etc. Adding the $3900 of porting and reinforcement to the same cams and intake manifold does improve things, but it certainly doesn't double the total gains.

All the tricks to get the heat out of the exhaust and keep it away from soaking into the engine does help overall. It would elevate knock thresholds on a given fuel and improve spool, etc. But it's a lot of effort for minimal gains for how most Supras are ran (highway roll-on racing, drag racing, half mile events) which is all much better when using E85/meth/race gas etc.

"More boost" has been the answer to virtually every question in the Supra world since the mailing lists... :rofl:
Not enough power? More boost.
Car doesn't scare you anymore? More boost.
Need to spank a Viper/Vette/whatever? More boost.
Need to spank a supercharged Viper/Vette/Whatever? More boost.
Job stressing you out? More boost.
Can't decide where to eat tonight? More boost.
Don't like what your wife named the cat? More boost.
Cat got sucked into the turbo while tuning your 2-step in the driveway? Find another cat, buy a bigger turbo, emphatically insist it's the same cat, More boost.
etc etc.

Until there's just no traction to be had, then the answer becomes "More tire"
When "More tire" finally nets more traction, then it's back to "More boost".

Yes, it's simplistic, but damn if it doesn't work :beer:
 

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Supra heads are expensive for little gains comparatively speaking, personally think it is worth it. I'm also very interested in the heads spoken about above. For comparison my 6 bolt LSX race heads that flow [email protected], 28" water gauge were 6-7k complete with roller rockers etc. The difference between those and stock LS3 style heads is huge, and so are the power gains just from the heads. Boost is always cheaper than head work.
 

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I gained 60 whp after installing kelford cams
What's the rest of the setup, and what cams did they replace?

That number is meaningless without context :beer:
 

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What's the rest of the setup, and what cams did they replace?

That number is meaningless without context :beer:
You're absolutely right, I should include more details.

It was from stock cams to kelford T202C tuned on AEM v2, pump 91 and meth. with a 6266 precision.
 

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You're absolutely right, I should include more details.

It was from stock cams to kelford T202C tuned on AEM v2, pump 91 and meth. with a 6266 precision.
Stock block/head/intake manifold I take it? Cast manifold or tubular? Manual or auto trans? Which turbine housing on the 6266? DP/MP/exhaust size? How much boost?
 

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I went with GSC S1 cams to match my 6870/ 1.0 AR. Not sure how much power they added. Good mid-range torque.
 
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no dyno?
 

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Discussion Starter #40
The Kelford T202C and the GSC S1 are very similar in duration, timing, and lift.
 
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