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NA 3.1L=>head & camshaft questions. No shortcuts, max


zredbaron

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Guest billyzbear

Just believe, buddy.

 

That seems alittle harsh. Is that how you wanted to come off?

The article was like four years ago and my memory isn't what it once was. Maybe it's the beer. Anyways, I posted on thier website hopefully someone else will back me up. Yes, it was alot more than you'd think. Just how hot do you think your oil gets?

I've seen your ignition setup before. It's real nice to set your own timing curve and have multiple coils. I would have to agree it's better than MSD or Crane solutions.

Are you still planning on going really high with compression?

Have you picked out your flywheel yet. I had an HKS 10 pound flywheel before but it was too light. The car would rev up real fast but would not hold it between shifts. 15 pounds is about right. When I was working at Nissan I used thier comp clutch's and pressure plate but found the disc to wear out in 6 months. The comp stuff was at cost and regular stuff was 10% over cost. I switched to a different disc's but still kept the pressure plate. It was either in or out and was pretty stiff. I can't remember what the brand was but got it at Ed's Place in N. Hollywood. Now, I'm useing the turbo flywheel with stock disc and pressure plate from Nissan.

I hope some of my exp. helped.

Billy

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Just how hot do you think your oil gets?

 

Lay off the beer and go read your source again. Typical oil temps on a street car are around 150 to 175F. If your chrome valve cover is adding 200F you're looking at oil temps beyond the design limits of any oil that you or I can purchase. On a race track you start worrying if your oil temps exceed 240F for regular oil and 275F for synthetic oil.

 

you may be right about the intake manifold getting warm, particularly sitting at stoplights and such, but at speed i would bet it is negligible (johnC, what does the racer's voice say?

 

With no air flow through the engine compartment you will see high underhood temps (typically 100F over ambient) but once a car starts moving over 20mph underhood temps drop to something like 10F over ambient. I saw a test on a Ford Contour using multiple temp probes that confirmed the above. The 240Z, with its more open engine compartment, should see at elast a similar reduction.

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Red Baron,

The vent tube on top of the cam cover isn't meant to see manifold vacuum, just filtered ambient-pressure air. Stock goes to the air filter, if you don't mind drilling a hole you could run it to one of your filters. I'm just using the itty-bitty K&N. It's the tube in the side of the crank that wants to see vacuum. I'm currently running that to a PCV valve to a balance tube setup on top of the manifold runners. I might try something goofy like eliminating the intake runner balance setup and have a PCV valve for each runner to a vacuum canister, from there to the crankcase and brake booster.

 

I'm running a fuel return line. Sould help keep the fuel a lot cooler. I have no heat shield between the header and the carbs, never have any vapor lock issues.

 

Billyzbear,

I don't think Zredbaron was really trying to be harsh on ya.

John, on the other hand...

:lol:

 

Just kidding, it's one big love-fest here at hybridZ. Just don't take anything personally. I've got the Sunbelt setup as well, one spring per valve. I limit at 7200, but the valvetrain should be good for a lot more, at least 7500. You really run to 8500+?! I'm not that brave. I don't think my bottom end is good for any more than 7500, max, and I don't see myself going that high with a stock diesel crank and 240 rods.

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Thanks Dan, I'll have to reevaluate all my hoses next time I get a chance. I'm glad billzbear pointed it out, so thanks bud. And no, there were never any hard feelings.

 

I don't plan on running past 7500 either. Where did you get the 8500 rpm figure? I don't think my diesel crank setup would like that very much...

 

Is that about right for the other 3.1L guys? No one goes past 7000-7500, right?

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zredbaron,

 

I got the high rpm numbers from one of zbear's posts. I don't plan on running mine that high. 7500 would be my absolute limit, and only for a limited time, like at the drags, or for a 3-lap time trial run.

 

My old 2.8L put out 240hp, flat tops, N42, 3 40's, Crane Hi-6 and cam 495 lift and 280 duration. It has good power from 2000-6500 rpm. I had a 510 lift and 308 duration cam in it along time ago but wasn't much good for street and had problems with wear. Good power from 3200-8500 maybe even 9000. I use to set the rev limiter at 9000. Never got that one on the dyno.
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Guest billyzbear

As for the chrome valve cover, I can't come up with the article. I can't say +200 degrees maybe it was 200 total, it's been to long. I do think your oil will run hotter with it. Normally, I think your oil would run a little hotter than your water. Take it as a grain of salt.

I put on the 45mm Webers today. I went from a 30mm choke to a 38mm choke. I haven't got them dialed in just yet. Mid-range it falls on it's face some and wide open seems a little lean to. I'll keep you updated on if it's worth it. Does anybody know how much cfm flows through a 38mm choke?

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Yeah, ask him. Thanks. I'm betting it includes rocker arms at $500. Not a bad deal, but I've got other places to spend $500, since I already have a fairly similar cam now. It would be a small step up for me, but a huge one going from a stock cam.

 

Okay, Jon. I spoke to sunbelt today. Their quote, not a final price, is $450 for the cam, and the price includes a set of the single springs. The quote is good for any grind that they have engineered before, if anyone wants a unique, never before attempted grind, the R&D brings the price up to $1500.

 

If you do end up calling, mention that Jim knows what cam he's putting into my E31 head, and that you want the same one, as it clears the 3.1L kit if you use a 2.0mm gasket. Again, the lift was in the neighborhood of .525" (maybe it was .535"? i dont remember for sure), and duration was such that the power band was 3200-7200 RPM. Their number is (770) 932-0160.

 

Good luck!

 

-Mark

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No problem, Jon. Also, those numbers will be solid sometime next week. He's got my head, and will run numbers and such soon.

 

I will formally have the cam specs next week sometime, I'll post em when Jim gets back to me.

 

Also, I opted to get exactly what JohnC had done to his head (ouch -- $$$$), except in an E31. Again, assuming the .534" lift will clear. Is your power from the 3200 - 7200 band too, John? 3500-7500? Higher?

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Haha! How did I know I was going to get an answer like that, John? For some reason I thought you were carburated, but silly me, I should have known that I have no clue what the hell you have done with that ridiculous car of yours...

 

Any reason you went with the Motec EMS over the TEC-3? Also, 65mm...thats way too big for 3x2 TB, right? So how exactly are you set up? Do you have a picture of this engine of yours?

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  • 4 months later...

Sunbelt head installed....finally!

 

According to their printout:

 

stock (head before any work) port flow:

.......................intake.................exhaust

.425" lift...........158.9 cfm...........110.2 cfm

.525" lift...........163.5 cfm...........118.4 cfm

(.525" lift never reached with the cam i had in it)

 

final port flow:

.......................intake.................exhaust

.425" lift...........180.6 cfm...........129.3 cfm

.525" lift...........201.6 cfm...........145.1 cfm

 

according to sunbelt, 200cfm by their flowbench (flow pro) is 225cfm by anybody else's (super flow).

 

The cam Jim set me up with has a lift of .520, and powers from 3500 - 7200. Cam lobe duration is 290° for intake, and 274.8° for exhaust (yeah, that seems ridiculously precise to me, too).

 

It should also be noted that Jim said the L6 motor doesn't start making any 'real' power until your lift exceeds .550". Damn.

 

My old head produced 157 rwhp, and this one produces 197. Quite a dissappointment considering my investment. On a positive note, it pulls hard to around 7250 rpms and sounds absolutely beautiful.

 

DynoPSep2004.jpg

 

DynoFSep2004.jpg

 

Any thoughts on why my rwhp is 50 hp < similarly built engines? Valve lift and carb tuning are issues....but 50hp?

 

Not sure what's going on under 3500 rpms...I've been meaning to call sunbelt but haven't got a hold of them yet. Jetting? Cam lobe?

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Got any lambda or other mixture ratio data? Without that you could be losing tons of hp in tuning.

 

Second, chassis dyno numbers don't mean squat unless it's relatively back to back pulls. Way too many variables.

 

Do a leakdown check just to make sure the bottom is sound. Eliminate the obvious and easy things first.

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Any thoughts on why my rwhp is 50 hp < similarly built engines? Valve lift and carb tuning are issues....but 50hp?

 

Don't start down this path of confusion, you'll just screw your head up! Don't compare chassis dyno runs from different shops with different dyno operators on different days. The numbers ARE NOT COMPARABLE despite all the BS you read in SCC, Hot Rod, etc.!

 

As Keith said, tune your car and compare it against others on a race track. Nobody races on dynos.

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Your A/F ratios are a bit wacky, hence the power drop if you call it that. I'd guess that you can eek out a few more hp once you correct the A/F ratios a bit. Your peak power was ~6Krpm and you're running at a not so power friendly 13.6-13.8 A/F ratio at the same rpm. Maximum power is achieved at a ratio between 12.5-13.0 so you'll need to richen things up a bit.

 

Based on your graph, it looks like you go super rich once you hit the throttle and then lean out as the engine builds rpm. Since you're running triples, this indicates two major things.

 

1) Your accelerator jet is huge. Although, I have found with cams of this duration that a super rich condition is required to reduce the stumble. There just isn't enough air velocity at these lower rpms with high duration and large valves. Adjusting the timing in conjunction with trying a slightly leaner jet should clean this area up a bit.

 

2) Your car gets progressively lean and then richens back up at high rpms. This indicates to me that your main jet and/or emulsion tube could use some richening. I would recommend bumping the main jet up a size or two and then give it another run. If the A/F ratio isn't down to a healthy 12.5-13.0 from 4K rpm up to redline then you may have to richen it further via emulsion tubes and/or richer main jets.

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First off, CONGRATS on gaining 40hp!!!

Secondy, ditto on the non-validity of comparing dyno results from different dynos at different shops in different states under different environmental conditions.

 

You're still running 40mm carbs, no? 44s or 45s, with 38 or 39mm main venturis should give you a broader torque peak, more peak power, and more power under the curve.

 

What's your compression ratio? Torque seems low, I'd expect 200+ lb-ft peak, over a fairly broad range. With that cam you should be able to run ~10.8:1 on 93 octane pump (I am at 11:1, with ~305/.550" cam).

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