Valve train dilemma could use some suggestions. - MY350Z.COM Forums



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Old 03-27-2017, 04:03 PM   #1
TT03Z
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Default Valve train dilemma could use some suggestions.

Well it came time to pull my motor and overhaul the turbos and add a bunch of upgrades. Here's the dilemma... I bought this car (03 350Z DE) with the built motor and Greddy TD06 20g turbo kit. It has Carrillo rods and pistons. I know this for sure. Now I have the engine out of the car for repairs and upgrades and I'm trying to figure what what valve train is in this car. Here's what I've done so far. I tested the lift on intake and exhaust cams with a dial indicator. IN .377=9.58mm pretty sure that's stock lift. EX .380=9.65mm which is slightly larger than stock lift. Stock lift is 9.57mm for both Intake and exhaust cams. Now, I'm wanting to get pretty wild with this motor. I'm looking for 800whp. So do I bite the bullet and order a set of JWT S2's or C2's and valve springs? Or do I just order just a set of valve springs. Can stock cams make big power in the DE platform?
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Old 03-28-2017, 03:48 AM   #2
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You will want some bigger cams so you can run less boost to get to your numbers. Also port and polish everything.
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Old 03-28-2017, 11:58 AM   #3
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Well i dont have the time to pull the heads and port n polish everything unfortunately. I'm going to order cams and springs for sure so I'm going to make the call to JWT and get a recommendation on cams for my setup. With the greddy 20g's the car should make better midrange power than topend power so I think the S2's and springs/shims with 256 duration and 10.92mm lift will be a good combination. I am open to other recommendations though as I have not ordered the cams yet but need to do it soon.
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Old 03-28-2017, 01:21 PM   #4
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Have you talked with any of the members at the Z Car Club of Nebraska for their input? They seemed like a pretty active group when I was in Omaha.
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Old 03-28-2017, 02:17 PM   #5
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Polishing doesn't take that much longer to do than installing a cam.. Porting yes but you still might be able to polish them up a little since you have it all off.

As far as cams there is tons of info by tons of people for cams. Google it and you'll have plenty of reading you can reference to make your decision on what exactly you want from it.
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Old 03-29-2017, 09:28 AM   #6
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Have you talked with any of the members at the Z Car Club of Nebraska for their input? They seemed like a pretty active group when I was in Omaha.
I have not contacted those guys. I really have not heard much about them at all. I have worked on a few of their cars in the past but have never really been interested in "car clubs". I did however make the call to JWT. I talked to Ben over there. Hes a super nice guy that answered all of my questions. He recommended buying the JWT C8 272 cams for my setup and power goals. So with that recommendation I will be hitting the order button today!
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Old 03-29-2017, 09:34 AM   #7
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Polishing doesn't take that much longer to do than installing a cam.. Porting yes but you still might be able to polish them up a little since you have it all off.

As far as cams there is tons of info by tons of people for cams. Google it and you'll have plenty of reading you can reference to make your decision on what exactly you want from it.

I suppose I could take the time to polish the ports on the heads and intake manifold runners. I was thinking of doing this but am limited on time. Now that i will be ordering cams I have some waiting time for those and can go ahead and do mabey some light porting and polishing. Keeping metal out of the valve galleys will be the hard part with the heads still bolted on
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Old 04-01-2017, 07:37 PM   #8
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since i just happened to be bored looking through random **** on the net ill chime in. You dont need cams for your goals. you can do 800 on stock cams and the stock cams will help with turbo spool giving you a fatter powerband, i did 850 on stock cams. Unless you are after a specific goal, such as you have a track you are on and spend most of your time there in a certain rpm range, or you need a specific rpm to get a specific mph drag racing theres no need to bother. The stock cams giving more low end grunt and "feel" more fun on the street as well because of the better torque down low. If the turbos you end up running are billet then the stock cams also help the turbos by running a higher boost pressure ratio. billet turbos flow exactly the same as cast until they get above 30 psi, they will still spool quicker below that but most of their advantages comes from the greater flow available from the blades being cut closer to the center "hub". Definitely dont port the heads because that will just hurt your powerband even more because your killing velocity for volume when the heads dont need it. stock ports will easily flow enough for 1k whp. All this stuff is twice as true because most intake solutions for the de suck for flow and your going to choke big cams out with the intake anyway unless your getting something made for the engine from wilson or similar.

if you have never done any port work absolutely DO NOT touch the heads yourself, chances are your going to **** it up. anything that comes into contact with fuel needs a rougher surface and most people who don't have knowledge on the subject will try to polish it mirror smooth. The rougher surface causes turbulence that helps the fuel mix with air. going too smooth will cause the fuel to fall out of suspension. Most high end porters will port larger and give a rough surface to form a boundary layer of stagnant air because air flows over air easier than it does metal(less friction), this doesnt seem to be done in the import world for whatever unknown reason......

from the sounds of it, if your trying to do it with the heads on the car DEFINITELY dont touch the ports because you will create a step that the air hits and causes all kinds of ****ery. Stick some springs and retainers on it and call it good.

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Old 04-01-2017, 09:44 PM   #9
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Jerry...where have you been?
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Old 04-01-2017, 10:08 PM   #10
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school, family, my own random bs trying to decide what car im going to take out this year since i picked up more. deciding if i wanna do the 96 camaro, the 79 camaro, or finish chassis on the z and run it. roll bar on the 79 i bought turned out to be junk and needs redone so might just run the Z.

didnt do a ton over the winter but i picked up a th400(not in pic), upgraded bender to air/hydraulic, worked on rearend some more, picked up the 79 camaro, picked up a few more ls engines, finished the cleanroom lol. Shops a damn mess at the moment but i just finished recovering from having my appendix out.

dark jester racing is about to start offering chromoly strut tower braces for 4th gen fbodys also, if they do well will expand to lca's for the rear and panhard bars.

I have 4 link bars coming for z as well as a third member.







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Old 04-02-2017, 07:16 AM   #11
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Well Jerry, thanks for that input man! I haven't and wasn't planning on porting n polishing. I did however buy the JWT C8 272 cams. The guys at JWT said that I could run a little less boost to make the power I want. I would love to see this car make 800whp. I will mostly be using the car for roll racing and drag racing won't be spending very much time on the road coarse this year. Planning on having a pump gas tune and then a C16 and nitrous tune. Did you make 850whp on stock sleeves and crankshaft? JWT C8's 272's.
After cleaning silicone for 8 straight hrs. I hate my life I also hate silicone. Clean it all off get it all nice n clean then use silicone to put everything back together...
Installed ARP main studs as well for some added strength.
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Old 04-02-2017, 08:19 AM   #12
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stock sleeves, stock cams, stock heads, modified intake by me, problem is jwt is trying to sell you parts of course they are going to tell you to run cams. same power at lower boost isnt always better, that seems to be a concept people can seem to grasp. Everyone says "you can make the same power at lower boost!" but no one can comment on why you would want to lol. (ill tell you the only advantage would be the possibility of running lower intake air temp, but unless you are plotting your exact setup on a efficiency island, know exactly how much your boost will drop, ect you will never know if that will actually happen.)

in reality a set of 272 cams should rev to 8k but they fall off way before that on this platform because the intake setup on these engines is garbage.(your NA setup DOES matter for turbo still, its still going to shape your power curve the). Hell the machined block in the picture i posted below will spin to 8k with 211/230 duration @.050(the c8's are 235 duration @.050). lift is about a tenth of a inch more but the engine also has about 14% more displacement per cylinder so thats a wash lol. the cam's arnt the limiting factor on these engines its the intake manifold, and your honestly not fixing that without spending several thousand on a intake manifold or doing a lot of work to the factory one cutting the runners and bellmouthing. you give up more rpm's down low than you gain up high which is why i recommend to people to engine swap past 1000 whp.

of course a stock crank...... the factory crank has shown able to handle over 2000 hp by scott porter racing in backup engines of his.
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Old 04-02-2017, 08:53 AM   #13
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Yeah I totally understand that they are trying to make money and sell parts. But the recommendations also came from Z1 Motorsports and Dynosty to get cams so I figured f*ck it while I have the motor out I might as well pull the trigger. Honestly I wish you would've said this about 4 days ago when I hadn't ordered the cams yet lol. But once again I appreciate your input and you seem like a very knowledgeable fella. You talk alot about the intake manifolds being the limiting factor on these engines what can be done to the factory setup without spending an arm and leg? I have a Crawford upper plenum I will be installing. I was thinking the nitrous would help compensate for the stock lower plenum setup. I'm going to run a 50 dry shot pre maf to help control IAT's.
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Old 04-02-2017, 10:39 AM   #14
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Less boost for same power equates to more efficiency, less heat, less chance of knock, can run more boost safely, means more usable power. Cams you picked are a good choice. I don't think the limitations are on the intake side jerry, but on the exhaust side. Small turbines and small log manifolds = quick drop off after peak torque due to exhaust backpressure. Just my 2 cents.
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Old 04-02-2017, 10:51 AM   #15
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Yea that's the first thing I'm going to upgrade next is my manifolds. So puny.
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Old 04-02-2017, 11:04 AM   #16
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I had my manifolds and turbine housings ceramic coated inside and out to help reduce heat and help smooth flow.
The passenger side manifold had a crack in it. It looked like a flaw in the casting where there wasn't enough iron in the spot with the crack. When the castings are flawed with not enough metal in a spot the metal will tend to pull apart when heat cycling. I drilled both sides of the crack and in the center. The center drill hole had far less material in it. I then grooved the crack. Preheated the metal and mig welded it with a copper core wire. I ran 2 beads on it and kept the torch on it to cool slow. Then I wrapped my welding glove around it so it could cool as slow as possible. Hopefully with the ceramic coating and proper weld it will hold together.
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Old 04-02-2017, 03:14 PM   #17
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absolutely not, unless your plotting the EXACT combo on the turbo efficiency island you dont know its more efficient, or less heat which means you cant determine if its less chance of knock or more boost safer which is the exact point im getting at. From my experience 99% of the time when running billet turbos and your right at the edge of where the billets start to flow more than cast you will usually have a HIGHER efficiency island by running that couple extra psi and typically the same or lower temps usually the same though.

he is going to need right around 32-34ish psi on factory cams to make the power he wants. plot that on billet 20g turbo maps(cast will need even higher numbers and at that point its a moot conversation) and you will run about 70% efficiency, now if you take the same airflow and drop it down to about 28-30 from running cams your dropping down to 65% efficiency. that is 381-394 outlet temps for the higher pressure ratio and 376-390 on the lower pressure ratio running cams at 80 degree inlet temps. 413-426 and 406-422 respectfully at 100 degree inlet temps. outlet temps from a 80% efficient air to air cooler on a 80 degree day which is pretty standard gives you 140-143 and 139-142 at 80 degree inlet temps and 147-149 and 145-148 on the 100 degree inlet temps. as far as safety margin the two are essentially identical, yet the cammed lower pressure ratio setup gives up significant usable power.

limitations on the intake side have been proven by both sasha anis(even if i still hold to his dynos being fudged in numbers the rpm gains he saw with custom intakes cant be faked and make perfect sense from a physics stand point.) and one of the former shop employees of sound performance i think it was? who cut the factory runners on the intake shortening them and bell mouthing them before i even did it and was able to take the same combo over 8k and still make power when it dropped off far sooner. let me try and find the thread i posted my old intake in and see what his name was.

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Less boost for same power equates to more efficiency, less heat, less chance of knock, can run more boost safely, means more usable power. Cams you picked are a good choice. I don't think the limitations are on the intake side jerry, but on the exhaust side. Small turbines and small log manifolds = quick drop off after peak torque due to exhaust backpressure. Just my 2 cents.

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Old 04-02-2017, 03:17 PM   #18
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my combo actually made 50 hp more average power than hals car at the same peak power using factory cams lol.

as far as a factory setup not much. In order to eliminate turns and smooth the airflow out you have to cut a significant amount of the runner out of the lower plenum. the problem is you have to cut so much out you end up right shifting the rpm band about 1000 rpms.

plenums do help but when it comes to intakes the runner diameter and length make up probably 75%-80% of the power band characteristics.

you can look up pulse harmonics for engines if your interested in it, most racers tune to the third wave harmonics.
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Yeah I totally understand that they are trying to make money and sell parts. But the recommendations also came from Z1 Motorsports and Dynosty to get cams so I figured f*ck it while I have the motor out I might as well pull the trigger. Honestly I wish you would've said this about 4 days ago when I hadn't ordered the cams yet lol. But once again I appreciate your input and you seem like a very knowledgeable fella. You talk alot about the intake manifolds being the limiting factor on these engines what can be done to the factory setup without spending an arm and leg? I have a Crawford upper plenum I will be installing. I was thinking the nitrous would help compensate for the stock lower plenum setup. I'm going to run a 50 dry shot pre maf to help control IAT's.
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Old 04-02-2017, 03:42 PM   #19
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From reading about cars with similar setups and power numbers they have made with the 18g and 20g turbos. @ 25psi on C16 with billet wheel 20g's and with the 50-75 dry shot I should be able to crack off an 800ish number. Theoretically. Other turbo cars running a 50 dry shot have picked up upwards of 150hp from the N2O alone. On pump 93 I would like to see the car make 650ish around 17-18 psi and C16 and N2O is where I would like to see a big number. I kinda have a wager going with a good friend of mine that the car will blow up before it makes 750+ and I won't be driving the car on the race gas tune very often. We can get into all the small details of making efficient hp but when the pen meets the paper there's only one way to find out how much power I can make with this setup. I totally understand that without the small details and crunching numbers there is no big power. But I'm going to use technology that already is proven for making power. I'm not on a path to develop any new technology. I talked to Logan at Dynosty and unfortunately they are booked until the end of May. Which will give me plenty of time getting all the bugs worked out of the car and figuring out the wiring for the Haltech. I need to wire the secondary fuel pump, nitrous, boost controller, wideband, and fuel psi sensor. Does anyone have a schematic of how they wired their external solenoids and relays?
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Old 04-02-2017, 05:08 PM   #20
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Just presenting my 2 cents, not here to argue and I do admit that turbo selection plays a big part, but if you map out VE for an engine across the rpm range and plot that on the turbo's compressor map, there will be some points more efficient for the turbo, others less, billet or otherwise. Some turbos do get more efficient with higher boost pressures, but for the typical small twins most kits use, the exhaust side will limit peak power. Increasing engine VE will result in more power where the VE is better at less boost. Yes, you lose some lower end with some cams, but it's not too far right shifted for the mild range most folks use, 260-270 degrees.

The intake side is a limitation for N/A but not nearly as important under boost based on my experience.

OP, those log style manifolds will help increase spool but those in combination with small turbines will limit your peak power. That style is better than the JWT logs I used before though.

I am injector limited here, but this is a nice fat torque curve for small GTX28s... at only 23psi (rising boost from 18 to 23 actually for this tune to maintain a flat torque curve). I credit the tubular manifolds, Kelford cams, headwork.


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