Jump to content
HybridZ
Derek

Twin cam head for the L6 from Derek at Datsunworks

Recommended Posts

I'm in a industrial complex and naturally most of my neighbors know what I'm up to. I was talking to one of them who has a classic car resto shop. He was commenting on how good it sounded from his place. I mentioned that I hope it wasn't as noisy when I get it on the road and he replied " it will be better when it's not an open header" To which I said it's running through a resonator and a muffler already.

 

Between the exhaust and the induction noise it's really loud at 5000 rpm:) 

But it's a good loud.

 

You have likely found your torque peak right now... That's the curse of the Honda's, the induction bark is FAR louder than the exhaust. CHP continually cites Hondas for "illegal exhaust" due to the noise and when tested it's rarely over 85-90 dbA... it's all induction bark. "It will be louder and lower under load"!

Share this post


Link to post
Share on other sites

finally, I'm curious about you running it without load.   a lot of people say not to rev an engine without load.  I looked it up quickly, and I've not found a basis for this, except for revving it till you hit or pass the redline.  Now i know you're not going to blow it by over revving (then again i'd be curious as to what over-revving this head would be;  at what RPM would you expect valve float to start? same as with the original honda head?)...

The float issue would be dependent on if you have all the stock stuff in there. The rationale behind the head was the copious aftermarket support for good things made of Titanium and other lightweight materials. There are billet rockers, titanium retainers and spring keepers, valves that are feather light.... Frankly, it may really be overkill for the bottom-end restrictions of the L-Series but there may be some durability advantages to some of those billet followers they make...who knows? With all stock, I would assume same float not that I've heard a lot of issues with valve float on the Hondas. Their valve train seems to be very stable.

 

The caveat on free-revving relates to pumping the oil out of the pan and starving the bottom end. On a VW Type1 it's not an issue in stock form. But put a lightened flywheel and hot cam with some induction and not increase that 2.5 qt sump and it is VERY easy even under load to accelerate the engine fast enough to suck the sump free of oil and pump it to the top end before it can physically drain back from the far reaches of the engine. Engines blowing at the top end of the drag race track can sometimes be traced to it... those deep 7QT sumps came out for a reason, aside from lowering the level away from the crank for decreased windage.

 

The BMW Engine recently had issues with it. They dubbed it the "Damocles Engine" due to owners hot-rodding free-revving. Thing is the tach needle had more inertia than the rotating assembly and "Boom!" Our Bonneville L28 would go from idle to 8,000+ faster than you think giving a WOT mash of the throttle. In fact, the cam we had in the SOHC Head was stable without float issues to over 12,500 rpms. If your tuning in right, it should zing right up there... 

 

http://autoweek.com/article/car-news/munich-we-have-problem-cadre-owners-raises-browand-stinkover-m3-engines-gone-bad

Edited by Tony D

Share this post


Link to post
Share on other sites

Just a quick update. I finally have the car on the road. I ended up doing a lot of rewiring and re-routing of things. No videos yet as I'm still in the rudimentary tune stage but so far it's running great. 

 

My definition of running great is it hasn't exploded:)

 

Derek

Share this post


Link to post
Share on other sites

"Did you put forged pistons in that thing? You will be sorry." Tony D to Bryan Blake after his triple itb cammed engine was up and running....

 

I posit, this will be similar. It's way too much head for the L28 in base form unless you twist it tight. But if you can twist, this thing is going to SING!

 

One thing which will be interesting is to get feedback on what difference the compression being low has overall. In VW's it was really overplayed and many of the best performance engines were in the high 7's to make the heat manageable, especially on the street. The torque you get down low is nice... but really it may not pay as big a dividend as many think. Other than  to the High Test Gas Company!

Share this post


Link to post
Share on other sites

Just a quick update. I finally have the car on the road. I ended up doing a lot of rewiring and re-routing of things. No videos yet as I'm still in the rudimentary tune stage but so far it's running great. 

 

My definition of running great is it hasn't exploded:)

 

Derek

Fantastic to hear mate!!! Cannot wait for videos.

 

I'm happy to say great isn't exploded all down the road either!!

Share this post


Link to post
Share on other sites

Thanks everyone. 

Stuck doing a bunch of bids right now so I don't have time to do the last couple of things to get it totally road worthy.

 

Here is a couple of shots of the engine bay mostly tidied up. The PCV system is still in Beta so don't judge:)

 

20170707041143-0bc65dbe-me.jpg

 

 

 

20170707041150-4e5806a9-me.jpg

 

I still have some final tucking of the engine bay wires but it's nearly there.

Edited by Derek

Share this post


Link to post
Share on other sites

Hey. Quick question.

With a head like this, do you expect power gains accross the rpm band? Or would you expect mimimal gains low down but sigbificant ones high up, for example?

Im just thinking whether a head like that would be good mostly for high revving racers or if it would be great for a street motor, giving it plenty of torque...

Share this post


Link to post
Share on other sites

Well I just got back from a drive and right now it's like someone flips a switch at 5000 RPMs which is what Tony has been saying the whole time. The head needs something to make it flow. Having said that my tune down low may not be perfect, the cam timing may not be perfect etc etc. I'm not saying it's a dog down low but up high it's pretty impressive. The potential is there for sure. Baby steps for now:)

Edited by Derek

Share this post


Link to post
Share on other sites

As usual Derek, amazing work, and the attention to detail is quite impressive.

Thanks. Having the delay on the cams paid dividends on detailing time. 

 

I feel stupid, but what could a "something" be to make a head flow?

 

Are we talking a turbo to help air along, say, or a set or specially designer headers (yours are kickass, i'd sacrifice 20hp for them!!!)?

That something is displacement and RPM if it's NA or else forced induction. Tony worked the numbers and you need like a 3.3 liter that you can sling up to 9000 RPM's to fully realize the heads potential with NA. 

 

I'm optimistic that I can make a little power with this setup. 

 

The sound is just amazeballs at 6 grand i must admit.

Share this post


Link to post
Share on other sites

What CR are you running?  Hopefully around 12-1 with a pent roof.  I have not read this whole thread to know.

 

Put a turbo on it and join me in the 750+ HP range  :).

 

This motor only has 8.5:1. When I build my stroker it will have at least 11.5:1.

 

I can't afford to play in your league:) I'll stick with my (hopefully) 250 -300 HP NA stroker range. 

Edited by Derek

Share this post


Link to post
Share on other sites

Im building a 400+ NA one now.  Should sound good with a fully counterweighted crank at 10K  :)

 

Do you have some quench in your head with tight piston to head clearance?

 

The block is just a .040 over flat top piston. The combustion chamber is racetrack shaped which leaves 2 quench areas of approximately  .6 cubic inches on the intake and exhaust sides. That is if I'm defining quench properly. I'm just the pattern maker:) 

 

If you are building a 10,000 RPM L6 then you really need one of my head castings:)

Share this post


Link to post
Share on other sites

Get it on a dyno and I bet your eyes go wide.

 

It probably is making GOOD power throughout the band-it's just that the cams, header, and intake all come into sync starting at about 5000RPM and all pull together to about 7800RPM.

 

Tried to tell ya early on about big cams, ITBs, and tuned length headers, but now you got the first-hand grins. My Apologies for the addiction, it never gets better. I bet every time you get in the driver's seat and turn the key you just have to give it a 5000RPM flick just because you can.

 

Now, when you get a chance to put together a higher compression stroker (say, 10.5:1 with the current cams and that compact chamber) of 3.0L or so...You'll be rolling into the throttle in 2nd rather than shift up just for the sound and the big pull!

 

How is the tuning going? Any tough spots that don't seem to want to smooth out or places that feel like they randomly go rich/lean?

Share this post


Link to post
Share on other sites

You're effectively running the Honda K20A2 VTEC cam profile, right? Not the low RPM profile? I would expect a huge high RPM bias.

 

And in my experience with ITBs, they rarely show gains over a single throttle intake until high RPM with big cams. They sure look and sound good though!

Share this post


Link to post
Share on other sites

Get it on a dyno and I bet your eyes go wide.

 

It probably is making GOOD power throughout the band-it's just that the cams, header, and intake all come into sync starting at about 5000RPM and all pull together to about 7800RPM.

 

Tried to tell ya early on about big cams, ITBs, and tuned length headers, but now you got the first-hand grins. My Apologies for the addiction, it never gets better. I bet every time you get in the driver's seat and turn the key you just have to give it a 5000RPM flick just because you can.

 

Now, when you get a chance to put together a higher compression stroker (say, 10.5:1 with the current cams and that compact chamber) of 3.0L or so...You'll be rolling into the throttle in 2nd rather than shift up just for the sound and the big pull!

 

How is the tuning going? Any tough spots that don't seem to want to smooth out or places that feel like they randomly go rich/lean?

 

I'm not saying it's making a ton of power. It's just makes a lot more power up high. I want to clarify that because we all know how the internet works. It's definitely  a lost faster than what I had. The tune isn't even close yet. I'm still working out a lot of little incidentals before I can really run it. But it's got quite the sound up high I will tell you:)

 

You're effectively running the Honda K20A2 VTEC cam profile, right? Not the low RPM profile? I would expect a huge high RPM bias.

 

And in my experience with ITBs, they rarely show gains over a single throttle intake until high RPM with big cams. They sure look and sound good though!

 

Yes that's correct. Since it's a Vtec killer I only have the big lobes. I knew the power band would be high I just was amazed at how pronounced it was. As I said before the tune down low may be crap and that will affect it.

 

I'm anxious to get everything stabilized so I can start tweaking the cam timing a bit. I pulled the valve cover again to put in V2 of my valve cover breather baffle and everything looked great. The valve train is a little noisy but there doesn't seem to be anything self destructing. Cam lobes look great. No grey oil from the bearing journals.

Fingers crossed:)

 

Derek

Edited by Derek

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×