yungone501

iTrader: (4)

Don't kid yourself.

Euro-R_Spec_TSX

LMAO Robert. Nobody even comes close to having as many J series parts as you.

Corey_Straker

So would this mean that a J37 bottom end with a J35a8 head with TL-S cams would offer the most high revving power?

yungone501

iTrader: (4)

IMO, yes. But maybe not.....

After having ran both the j35a8 and the j37a1 heads on the same engine (TWICE!), I've realized that the j35a8 heads are much more efficient at breathing at higher engine speeds. Though I never ran stock cams throughout all of this, and on one engine I was running boost, I could definitely tell the tumble ports (j37a1) drop power up top using the j35a8 TLS cams.

But here's something to think about, back in 2005 (nearly ten years ago) the RL was skimming the 300hp mark with the j35a8. Since then, Honda has increased the displacement from 3.5 to 3.7 (that was said to add 20hp alone!), improved cylinder head design (said to have made 7hp alone!), made intake and exhaust improvements (made ANOTHER 7hp!), added intake and exhaust VTEC, added low friction rings and machining, increased compression 2/10's of a point (11.0:1 to 11.2 :1) and even after all these improvement to the "flagship" model powerplant, they still ONLY managed to squeeze another 15hp (290hp to 305hp) since then!!!??? This is clearly purposeful detuning. But what for?

I'm not a engineer or anything but this could only mean one thing: Build the engines to make the same power, more efficiently and gain leverage on both reliability and emissions. If the engine produces the same horsepower but with less effort and without adding more fuel or revving the engine up higher, well then that's a good thing. That's also a "Green" move on Hondas behalf.

Maybe once I finish this short stroke 2.7 build I'm doing I'll see wether or not if the heads and cams are capable of what I think they're not capable of. Lol. Otherwise, until the tumble port heads are flow benched in comparison to say a set of j35a8 heads, we may not know until someone uses them on an engine like the 2.7. No there's something to think about.....

Otherwise, i have major respect for the j37aX heads. They definitely have their purpose and make a great swap for those with 3.2/3.5 engines that aren't looking to make a high revving NA build using them. They are so far proven themselves to make really great low/mid range power very easily. They even cost around the same if not less (j37a1 07-09 MDX that is) than the j35a8 heads do.

Euro-R_Spec_TSX

To add to what Robert (J-series guru) said, the J37 engines in stock form probably have a broader torque curve than the other J-series engines.

thisaznboi88

iTrader: (7)

There is a j30 with the j37a1 head and dyno graph on v6p

yungone501

iTrader: (4)

I'd have to agree with your statement Eric. And I'd bet even more so on the j37a2/a4 engines with the addition of exhaust VTEC. Honda doesn't really disclose much information on this setup but its most assuredly to improve the j37's already massive torque levels. Even the j37a1 creates an unusually high amount of torque way down low that moves the MDX like a feather.

I've owned both variations of the j37a1 that splits into two category's: the 07-09 MDX j37a1 (gen 1) and then the 10-13 MDX j37a1 (gen 2). Both engines are said to produce 300hp: the gen 1 at 6000 RPM's and the gen 2 at 6300 RPM's. Then there's the torque: the gen 1 is 275ft lbs at 5000 RPM's and the gen 2 270ft lbs at 4500 RPM's. Driving the 2007 MDX (gen 1) I had, you could feel the endless torque pull that fat pig all the way up to redline without hesitating anywhere in the powerband and even with all that weight, you could TELL it had every bit of 300hp. Then, we traded that fat pig in for another one which is a 2010 MDX (gen 2) and although it did have one more gear in the transmission, I couldn't believe the massive difference in power this thing churned out! Even the engines tone as it climbed to redline made a much more aggressive sound than the other.

There were numerous reported differences between these two generations of the j37a1 engines. Most notably was the camshaft profile which is extremely similar to the j37a2 and j37a4 cams as well. The cams basically did exactly what Eric said above, they fattened out the torque production throughout the powerband. They didn't make the peak torque higher, just longer. Honda definitely made huge improvements not only with the later generations of the j37aX engines, but also in the manner of which their engines produce power with ALL of their current 3.5 engines as well. Honda mentions the increase in both camshaft lift and duration in their later models but looking at the static numbers, it appears that the intake numbers were lowered. If I remember correctly, I've measured the base circle on the newer cams on both intake and exhaust and they were the same diameter as previous cams produced. This means that the change was probably made by altering the rocker ratios which now that I think about it, they do seam a little longer from the pivot point on the rocker shaft itself.

I'm currently in Florida with the family on vacation but I have been brainstorming about the differences on these engines for the past few days and do plan on pulling some new data and figure out what the hell they did to make the lift changes when I return. Maybe even get some concrete data on the difference between the j35a8, j37a1 gen 1's and the j37a1 gen 2 heads and cams. I would really like to ship all three heads off to get bench flowed to get max lift numbers and then the lift numbers using each heads own factory camshafts. Now that would be nice....

Sonnick

I currently have the J37a1 (gen2) heads sitting in my room along with the 8G Accord ported runners. I've been contemplating selling them because I would like to rev my Accord to ~7200. After reading through this thread, it seems the J35a8 heads may make more power up top, but it also seems like they won't. So now I'm stuck in a corner lol. The heads look great and the gen2 cams have higher lift & duration (coming from Honda) than the gen1s, but since they are SUV heads, that could mean they broaden the torque curve moreso than make power up top, as Robert has already suggested.

Decisions, decisions................

thisaznboi88

iTrader: (7)

Wait for my dyno of the j35a8 heads :p

FamilyGuy

Most likely for economy and emissions, while adding a bit of power to keep up with others and meet customer expectations as well, not to mention cars seem to keep getting fatter these days, so more weight to push around, and you don't want to lose performance because of that. Reliability most likely increased as well, but this is probably more of a byproduct than a goal. It's not like Honda engines suffered from short life spans or reliability issues. Fuel economy and the ever changing emissions regulations usually rule priority in family sedans these days. They push a little more performance out of their sport models, but IMO Honda is still conservative here, with the exception of the NSX and (if released) the turbo Si in Europe (next year?).

kingkong_dav

FYI the zdx does come with exhaust/intake vtech. Info from wikipedia

yungone501

iTrader: (4)

As I mentioned Brian, we REALLY need to get these two castings bench flowed and see how they compare to each other. I've found some very conflicting information in regards to my own personal opinion on the tumble port head castings but I'll just say this and then let you decide: RealTime Racing/HPD have teamed up on one of their SCCA regulated cars that's a late generation TSX (10-12?) that's using the infamous R70 casting 3.5 block that's been race proven by HPD alone up to 450hp+ in factory trim. They basically increased power from lower 280's to around 350hp using 1.3 additional compression points, the j37a4 cams (on the stock R70 castings) and tuned with a Motec ECM. Other than a custom exhaust and HPD valve springs to raise the rev limit up to 7200, that's pretty much all that's been done to make the extra 70 horses. The R70 heads are essentially RKG castings which are from the j37a4 and aside from redesigned rocker bridge bolt provisions they are also the same as the RYE castings from the j37a1 (07-09) engine.

Point I'm trying to make beneath all that is if HPD didn't see great potential (which obviously they have) at such high rev limits, then why would they use them on their NA 3.5 race car? WE NEED FLOW DATA!

Btw, the R70 castings can be found in nearly all of Honda and Acura's line up 09 and beyond, pre-direct 3.5 engines as well as the 10+ MDX 3.7. Its a very versatile head. The downside to running it on any pre-j35z engine is that one must use the valvetrain, cams, lower runners, injectors (due to flat spray pattern instead of cone) so make a parts list if anyone plans on doing this.

Through my research and to support my own opinion here on the tumble ports heads having less potential at higher revs, I've learned that they produce excessive turbulence when velocities get above the tumble designs advantage...which can vary from engine to engine but generally this occurs in midrange rev points. Lastly, the s2000 has one of the greatest flowing heads ever to be cast and mass produced and having has an s2000 head and the j35a8 head side by side, I can say that the heads closely match in port shape and angularity not to mention combustion chamber shape (though the s2k is slightly smaller).

The ZDX also runs the R70 castings that, although can be easily adapted with the rocker bridge and rockers from the j37a4 dual VTEC, does not have the exhaust VTEC from the factory. It runs the exact same setup as the 10-13 MDX runs actually.


Since I'm here, I'll shed a little more light on the whole j37a4 cam and head research I said I'd do (but haven't finished yet). Even though the cams from the a4 are numerically much lower in max lift for the intake and much higher on exhaust, their base circles are slightly smaller and have very similar intake lifts to say a j32a2 cam and slightly less lift than the exhaust lobes from the same cam. I can physically see that the LSA as well as duration is noticeably longer for both intake and exhaust as well as primary and secondary lobes so that explains a lot on decreasing lift. I still yet to match these cams to the j37a1 which was my original quest but that's what I've got so far. Also, as I mentioned earlier, the j37a4 RKG heads and the j35zX R70 heads are practically the same casting with virtually no detectable differences between the two. This is what allowed HPD to adapt the TSX heads to the dual VTEC.

screaminz28

iTrader: (1)

I'm just curious, but how are these cylinder heads flow tested? I know in the domestic world, there is much contention over the use of a pipe on the exhaust giving false or 'overly optimistic' flow numbers. Also, is it standard practice to use an 89mm bore for the J series heads?

S.Blazes

so if it fits a j32a3 it will fit a j35a8 ?
what if i run a 3.7 crankshaft as well?

S.Blazes

I have an intake upper manifold lower runners injectors and fuel rails from a 2013 accord v6 6 speed coupe.

I want to swap it on to my j35 but there is not location for the intake butterfly and the purge control valve solenoid. I'm thinking about leaving my purge control valve solenoid connected and attached to the manifold just leaving it open and not returning to the intake manifold, I'm not too sure what to do about the intake butterfly though.

are these runners and injectors only made for the newer style j series heads?

yungone501

iTrader: (4)

Just depends on who you send it to and what you ask for. As you would imagine, many people have different theories on flow analysis. Me personally, I prefer testing ONLY the head itself because that's the only variable changing in my own engine configuration. Given each head that's tested is of the same major design or casting, other small variables such as valve seat angles or valve undercut are all part of the reason why we want flow analysis done to begin with.

As for the bore size, this is something you define when sending the head(s) to be tested. Most of the heads produced for the j-series (even most j37 heads) have an 89mm diameter chamber. I'm quite certain this was done not only for interchangeability but also for unshrouding reasons. If using a 89mm diameter chambered head on a 90mm bore block, you should modify the quench area to better suit the head for the larger bore IMO.

Yes, these heads will work on any 2nd generation j-series engine with the single port exhaust heads.

And because all j-series engines have the same compression heights on their pistons, you don't need to worry about running a piston up through the bottom of the head. You will, however, need to recalculate the compression ratio obviously. Even if you remain at the same original bore size, you are effectively adding more volume from the increased stroke. This is probably one thing I see most people overlook the most when changing bore or stroke. This goes for the heads as well. If you are swapping to a 90mm chamber from an 89mm chamber, do your CR formula and ensure its not too low or high.

I'm assuming you're referring to the "2007 TL" j35a8 here. Simple answer is no.

You can use the upper manifold but as you've already discovered, there will be no intake manifold runner control (IMRC) valve but you can leave your old valve connected to satisfy the ECM from throwing a code. As for the other components, the lower runners and the injectors, these are practically useless without the tumble port heads. The runners have the tumble port shape on the side that attaches to the heads and the injectors have a flat spray pattern (again, complimenting the tumble port design) and not the typical cone shaped spray pattern that your current head ports are optimized for. Using any of these parts (including the upper manifold) will actually create a power loss unless the appropriate heads are used.

You can find a cheap set of heads online with the tumble port design. You could expect to see a large horsepower & torque increase (especially in the low/mid range) if the correct cams are utilized. I'd also recommend the purchase of FlashPro to get the most out of the entire package though.

yungone501

iTrader: (4)

Shipped my j37a2 cams today for some re-profiling. Wonder if these guys have any idea what they're getting into with a SOHC camshaft that has 6 lobes per cylinder....hahaha!

justnspace

iTrader: (1)

^lol.

Grand_hustle17

Im so into this thread... This is something one normally would have to go to v6 performance for... This is great info n should be a sticky... Im looking into grabbing the mdx cyl heads within a months time... I havent really given much thought to cam or cam profile as yet.. Right now im thinking to keep stock cams or go with type S cams.. What springs and retainers do you guys go with??? Im from a nissan background and i think Apr makes a spring/retainer kit and head studs for those wanting to extend revs but even if i do chose to extend revs in the future 7100 is highest i would go... All in all i want to go with 3.7 heads myself but hesitant because this is my 1st build on a platform im not most comfortable with

justnspace

iTrader: (1)

^i'm using stock springs and retainers that came from the MDX heads...
and i'm using the type-s cams in my build.

3.2 shortblock with 3.7 heads and 3.5 cams.
thats it.

Grand_hustle17

Oh o.k.. Well i love how you are keeping it simple.....

Grand_hustle17

One other question.. Has anyone ever test the injectors to see how much power they can handle without maxing their duty cycle?...

justnspace

iTrader: (1)

well, you did say you were a little scared about a platform that you didnt know.
keep it simple.

Sonnick

I have 2nd gen (2010) J37a1 heads I mayyyy be willing to sell. Along with ported 8G Accord runners. Just saying.

This is a great thread, I just can't see myself doing the heads when I just redid my trans and still need a cutout & tune. Hopefully the J37 heads with the right cam will be able to rev and make gobs of power!

swoosh

iTrader: (5)

subd

Euro-R_Spec_TSX

Nice bumpsticks Robert. Are you going to share the cam profile? Would be nice to know what the lift, total duration and duration @0.050" is.

Grand_hustle17

Was there any "before" dyno pull?

yungone501

iTrader: (4)

It all comes down to your expectations with the motor. I was always taught to have a power/purpose goal for whatever engine you're building. As long as you have these two and you build accordingly, you won't be upset. Just remember, you will (generally speaking) sacrifice one thing for another: power for reliability, top end power for low end power, smooth idle for rough idle and so on.

My reasoning for saying this is because if you stick with a factory cam, I wouldn't expect a dyno monster. Luckily, cams and tuning are some of the most limiting factors for the j-series engines which means you can tweak one or the other (or both) and see impressive results without really having to go ALL OUT on the build as long as the correct factory parts are used. I'm certain one, if using the right cams and tune, could approach sub-400hp numbers pretty damn easily.

And if anyone in the crowd is reluctant to believe this, just read around a little bit online and you'll see what I mean. I often consider going the NA route with the 2.7 build just to see what sort of ridiculous numbers it could produce.....but then I quickly snap back to what 15-20lbs of boost will feel like revving to 8k on 6mt.

With a 3.0 intake and a 2.5 oil pan?

If using the j35a8 and later injectors, I wouldn't go much further than 350 tops. People forget to factor in fuel trim changes by the ECM when something such as a cold night, lazy o2 sensor, or a dirty MAF comes into the equation. Keep room for engine management dynamics or error. With companies like Injector Clinic around nowadays, there's no excuse for approaching duty cycle limits. Also, for those running forced induction, never under estimate the power of a fuel solenoid/nozzle setup from a nitrous setup running on its own vacuum actuated fuel pressure regulator. I used a setup like this for about a year once and was amazed at its performance and accuracy. As far as I know, that's original. Mechanical fuel injection at its finest baby!

FYI, I haven't had this done YET but since we're on the subject...

Bill at Gude contacted me today after having received the cams and once they were profiled for the choices I had based on the factory grind, this is what his recommendation was for the cams:

J 37 VTEC CAM SPEC TURBO
PRY. EX. LIFT @ CAM .195 DUR. 218 @.025
VTEC. EX. LIFT@ CAM .220 DUR. 242 @.025
PRY. IN. LIFT @ CAM .235 DUR. 228 @ .025
VTEC. IN. LIFT @ CAM .305 DUR 284 @ .025

The grind is not much different in regards to lift, I think he said .015" is the most he would be adding at the highest lift point. The biggest change is gonna be made to the duration. Opening the intake up sooner based on the VTEC specs for exhaust lobe would make some pretty big differences on making this short stroke engine minimize lag as well as produce plenty of flow up to 8k revs. Remember, the lift values should all be multiplied by the rockers ratio of 1.65 to determine actual valve lift.

They should be cut on Monday. Solid progress will have been made for the build. Let's get this show on the road!

Grand_hustle17

Well thanks im not going for crazy power 280-300 is good with me... I think i care more to have a slightly better tq. If only lightweight flywheels worked with stock clutch

justnspace

iTrader: (1)

umm change out the stock clutch.

swoosh

iTrader: (5)

assuming you are base 6MT, you will be able to get to 280 without much issue....I have seen fully bolted on Base 6MT's dyno in the 270-280 vicinity....fully bolted on Type S 6MT dyno in near the 300whp vicinity....

all this without touching the heads or tune...

but with better flowing heads, decent cam profiles am sure you will see a 10% (or maybe more) power bump....



I agree with Robert on the goal...its good to have a goal defined so you can pick and choose the route you want to take to get there....

I am base 5AT and I want to get to the 360whp mark...its a very far fetched dream but lets see what route I want to take to get there....

yungone501

iTrader: (4)

I realized I made the mistake of not mentioning the fact that even if you're running aftermarket cams and a tune, you will have to rev the motor much higher. Especially those of you with the smaller cubed engines. I know RealTime had to rev their 3.5 to 7400 in order to achieve 350hp. And that's using an aftermarket cam, aftermarket tune/ecu and of course springs and retainers that enable the higher rev limit. That's really all it took them! I know TB Motorworx sells 10k springs and retainers so we are no longer limited with the j-series anymore in regards to power production.

Euro-R_Spec_TSX

Would be nice to know what springs and retainers were used in that RealTime J35. And also if they changed the valves.

thisaznboi88

iTrader: (7)

how much does he charge to spec camshaft? I have some stock camshaft that I am willing to get spec

screaminz28

iTrader: (1)

I know someone said lift was limited on the J due to the design of the rockers (may have been a different thread). I could be in the minority but I think high lift cams, >500 lift will be a game changer for the J. With the flow these heads have stock, they aren't taking advantage of any of it with the low lift the stock cams have. I know there are some B and K series cams well into the high 500s for lift.

Does someone have a deeper explanation of what is limiting the lift? Maybe a graphical representation? I've searched but can't find anything specific.

Euro-R_Spec_TSX

I think it's the holes in the head. If the lobes are too high, the cam won't fit through the journal holes.

yungone501

iTrader: (4)

I've talked to the RealTime race team (which is now a division of HPD) manager Michael when I called them about potentially buying their race cam profiles
from Megacycle Cams and the conversation drifted over to the HR28TT and its technical details. Michael told me that they, before having merged with HPD, had to purchase the valvetrain under HPD's race program and used ones very similar to another vehicle which I think was the Civics(?). But they weren't anything that the general public has access to. I've researched the whole HOD race program and it requires full on involvement with an official race organization in order to be eligible to order HPD's performance parts.

Also, Megacycle Cams advertises themselves as a motorcycle only cam design company but were hired by RealTime/HPD to develop the j37a4 racing camshaft profiles. After having been giving approval from Michael to use the cam profiles that Megacycle possessed, I was quickly discouraged to discover how much money Megacycle was asking to make these cams for me using my own cores! Let's just say it was a number that would've damn near payed for my entire engine build. Michael with HPD did speak VERY highly of them though...if anyone wishes to pursue this idea and has the cash flow to back it up.

Here's the cam specs that were created by Megacycle for HPD on these cams:






Not sure, it may be a fee that was included with the regrind service but if that's all you were looking to do, I'd simply by degree wheel and a dial indicator from Jegs and do it yourself. Very simple task to do yourself.

First of all, I made nearly 430hp once with a static valve lift of .481" on my NA small block 327 V8 motor. Duration is much more important than lift numbers when making big numbers on an NA motor. Especially when the cam designer knows what they're doing. IMO, just throwing big lift to a camshaft is a lazy way for a cam designer to make power from the engine. Precise opening and closing of the valve and at what ramp rate in accordance to the engines mechanical specs is the game changer.

However, to answer your question directly here...

Eric named one of the reasons why simply adding height to the lobe itself wouldn't be an option. The lobe can be as close as 1/32" from hitting the cam journal at its peak not to mention nearly as close as that from hitting the actual head casting itself once it's installed and rotating in the head. So even if the cam journals tops were made to be bolt on or removable, a great deal of material would have to be removed in this area to ensure feasibility.

That leaves (re)grinding as the only solution to increasing camshaft lobe lift. On the j-series head, this too is limited for two reasons. One is the material height of where the valve spring sits on the head interferes with the possibility of adding more static lift (thus more rocker movement) to the valve. The fix is simply machining this area and decreasing its height. The second, though it doesn't physically interfere, will cause long term negative effects to the valvetrain. This is because when you regrind any camshaft, you are effectively decreasing the base circle diameter in accordance to whatever lift is being added to the lobe. This means that now the rocker will physically rest at a lower position thereby changing the geometry as well as the characteristics of how the rocker now optimally functions for increased reliability. The rocker rests at a lower position as well as sits at a lower angle which means that the roller itself is now being subjected to different ride angles on both ends. At the end of the tandem pole, the valve sits closer to the edge of the valve tip which will eventually cause premature wear and component failure.

Many people get thousands of service free miles without any trouble/problems whatsoever and this is the typical outcome of many regrind camshaft scenarios. But the increased likelihood is now there for the aforementioned problem to occur and this means big problems for anyone that invests lots of money into their engine. There are other effective ways to add lift such as changing the rocker ratios but in the end, costs I'm sure will be neck and neck with the same potential of having reliability concerns. THIS however is the price we pay to play. You must compromise as well as sacrifice certain areas of engine longevity or drivability when building a performance oriented engine. This is one thing many people don't consider or even know anything about...especially with a forced induction build.

screaminz28

iTrader: (1)

I appreciate the technical explanation as to what is limiting lift. However, we will have to agree to disagree on the lift vs. duration aspect.

Yes, you can make power with low lift, I won't dispute that. I'm guessing your NA 327 was turning pretty high 7K+? with that kind of lift to get that amount of power, and the duration probably was enough to make it not much fun to drive. That is, unless you're talking about a destroked LS that is. The duration needs on an older SBC with that kind of lift wouldn't be what I would call "daily driver cooperative" for most people. With that being said, I've run a 24x/25x cam in a 346 and tolerated it just fine. It made 420 whp on stock heads too.

If using lift is lazy, I'd say ignoring it is short sighted. To focus just on duration will succeed in moving the power band higher, but in other posts, some people with ported heads only saw improvement above .350 lift, and most gains were over .500. The lift is so low on theses cams that it's effectively useless porting them. My point as to the increase in lift is that there would be exceptional gains in having camshafts that would effectively use the flow that the heads have stock. I think it's in the 260s @ 500, don't quite recall.

Personally, I don't want a high duration weak low end 3.2/3.5/3.7 that needs to rev to 9K to make good power. I'd rather have it peak before 8K, and make more overall torque, which the increase in lift would contribute to.

yungone501

iTrader: (4)

If you have a NASCAR engine and a Formula 1 V8 engine, you will notice that the F1 engine is nearly half of the displacement as the Cup motor but they will roughly produce a similar amount horsepower. Because the Cup engine has more displacement and due to the way it's designed, it will produce 2.5 more times the amount of torque the F1 engine sees. Though you would think the higher torque Cup engine would make for a "faster" car, they're damn near neck and neck in performance but each dominate their own battlefield.

My point here is that they both pinnacle race engines that are built totally different with comparable performance. The Formula 1 engine does it using a SMALLER THAN USUAL displacement which is applicable to the j-series in the perspective. To achieve more power, it's much easier to produce power by revving the engine higher and sacrificing torque...especially because the fact that the j-series is lift limited and it's higher lift cams/short duration cams that produce more torque.

I respect and also value your approach to reaching an achievable level of power in the manner you described. But when applying either strategy to the j-series, it will be the higher duration/low lift camshaft profile that outshines here. This is precisely why I have chosen the short stroke approach here over the larger 3.7. The short stroke will help me to reach higher engine speeds while the increased cam duration compliments.

As for streetability, it's no different than driving a hyper-sport motorcycle. You simply stay in the usable powerband when driving. Simple as that. Most people that daily the j-series engine are more than likely already familiar with this...especially those who have a 3.2 liter and below.

thisaznboi88

iTrader: (7)

What is the seat pressure of the OEM valve springs for the mdx?