1989GTA

"So you're stating that the really rough graph with (smoothing set to 0) in the upper RPM's can be caused solely by being too rich? Here's the biggest AFR graph I can get you."

No, not at all. It could be something with the dyno. That is why I suggested the smoothing be set at 5. Now looking at the graph in post 9 with smoothing at 5 the graph looks fine to me. As to the AFR I would try to get as close to 12.5 or 12.6 across the board. Once that is done we can see where things are at. I would say the numbers are on the low side but again that could just be the dyno you are using.

Sales@Tick

iTrader: (3)

What lifters?

It looks like something in the valve train isn't happy.

I've had combos have lifter bleed down that look identical to your curve past 5500rpm. Normally this happens with LS7 or OEM lifters. We swapped to aftermarket in those instances and the power carried.

JimMueller

iTrader: (9)

To the best of my recollection they were new LS7 lifters, installed with the motor built in summer 2010. What replacement lifters would you recommend for a 99% daily driver which will see limited autocross/HPDE activity?

Sales@Tick

iTrader: (3)

Either a set of Morel 5315's or Morel 5290's.

5315 is a drop in that still utilizes a tray. 5290 is a link bar with a .700" diameter tappet.

That really looks like lifter bleed down I've seen in about 5 different motors now with OEM/LS7 lifters.

JimMueller

iTrader: (9)

Man, I hate it when I need to replace internal motor parts... besides I can never leave the rest alone... if I have to replace lifters, then I might as well do the trunion upgrade, and I might as well get stiffer pushrods, and if the heads have to come off, why put the same heads back on, and if using a better set of heads, need a matched cam...etc

Assuming it's the lifters, am I okay to keep driving on them so long as I stay below 5000RPM until parts arrive?

Sales@Tick

iTrader: (3)

Assuming it's the lifters IMO you're fine to drive on them.

JimMueller

iTrader: (9)

Cost aside, how do the Morel 5315 or 5290 compare to these models for my use?

Comp #15956 or #15850 short travel
Johnson #2110 or 2116 slow leakdown rate

Edit: While this log wasn't from the same pull, it was from a WOT street pull back in April. Noticed how rough the MAP readings are.

Sales@Tick

iTrader: (3)

The 5315 is a drop in lifter as is the Johnson SLR.

The Comp's are link bar lifters.

JimMueller

iTrader: (9)

Going through my old posts and I thought I'd update this. Yes, it's been over a year, but it really wasn't critical and had some other BS come up also.

I was trying to ensure all the support systems were up to the task before throwing significant money at it. Since my last post, I replaced plugs, ignition wires, and performed a compression test (all near 200psi dry). I also replaced my alternator, installed 2.75" alternator pulley to prevent overcharging the alternator, installed an Autometer fuel pressure sender and plumbed it into my old EGR harness so I could scan it with HPTuners. Battery voltage is now staying near 13V all the way to fuel cutoff, fuel pressure is normally around 60psi but falls to low 50's in the upper RPM's.

I also did some street tuning, trying all EQ ratio's corresponding to AFR's between 12.0 to 12.6 to see which gave the lowest elapsed time between RPM breaks in the calibration... ended up using anywhere from 12.1 to 12.4 across the RPM range. Didn't have time to try above 12.6, but from what I've read LS3 like it a little richer. Wanted to do something similar with spark advance but never got around to it.

Went to a monthly dyno day yesterday, using a different Dynojet than referenced earlier, with similar results - unusual HP curve after 5500RPM. Since it was just a dyno day, they don't take AFR readings. Attached is all I have at the moment, I'll see if I can get the actual dyno file. While the event is useful, it's a glorified sales pitch to find problems in your graph and to switch to their in-house tuner to isolate and possibly fix the problems.

So from my other threads, I've been told:
Fuel pressure: If I make a little bit richer and it doesn't change the pressure, then low 50's at WOT is nothing to be concerned about.
Intake restriction: MAP kPa bounces around little bit at high RPM, but based upon the size of my intake tract prior to the manifold it's probably just pressure waves.
Exhaust: Can't do much more with it without an expensive upgrade which may make it too noisy for my preference.

I have some suspension upgrades I need to take care of first, then I plan to start saving to rebuild everything from the lifters up. Since it doesn't seem to be causing any reliability issues I won't worry about it. If for some reason I can't do the whole top-end, I'll start with upgraded pushrods & new valve springs and hope that I don't need to replace lifters.

I do have a set of Crane 3/8" pushrods I used in a prior LS1 motor, details in the following link. Any harm in replacing my stock pushrods with these Cranes and re-testing? Using the factory rockers I can just R&R the rockers and tighten to 22ft-lbs assuming I have the correct length pushrod, right?

https://ls1tech.com/forums/generatio...l#post18677910

DietCoke

iTrader: (18)

I'm just blown away you're using 5 year old (now) valve springs, singles at that.

You're brave.

Numbers are right, you aren't going to make more then that with a catted y pipe and a tiny cam. Thats why the thing chokes up at 5500, runs out of flow. Don't believe me, drop your y pipe and run it again and watch your curve look completely different.

JimMueller

iTrader: (9)

While it's my daily driver, I don't put many miles on it. Work is about 15 miles roundtrip and I typically don't go too far out of the area with the exception of LSFest 2010. I'd have to look up some receipts, but I'd guess I'd be close to 30-35K miles on the motor. I requested a endurance lobe and the PAC 1518's are nitrided for extended life, so I figured they would still be okay. I could pull one and have it tested I guess.

Do you mean drop my y-pipe and dyno with open headers?

DietCoke

iTrader: (18)

Dyno, log ve, doesnt matter.

KW Baraka

iTrader: (7)

That's very nice.

30K miles is a lot of miles on valve springs with a performance cam.....making dyno runs.

If you're just gonna putter around town to the tune of 15-20 per day, they may be alright. But if you do 'spirited' driving, you really should consider swapping in some new springs.

Me? I'd swap them just because they have 30-35K miles on 'em.

KW

JimMueller

iTrader: (9)

I've been looking into valvesprings. Only interested in conical or beehive for the better harmonics. What I found so far:

I've read that more than 400 lbs open pressure with the OEM rocker arms isn't recommended, and my exhaust is .600" valve lift. Although I _really_ wanted to use the conicals, this appears to cause a problem since the minimum open pressure is 412. So that leaves me with:

How much seat & open pressure will work best overall with an EPS 222/230 112+2 .596/.600 cam, LS7 lifters, 5/16 or 3/8" pushrods & OEM LS3 rocker arms? If I later find that the lifters need to be replaced and I went with a non-OEM hydraulic lifter, would that change the desired pressures? I need these springs to be a drop-in... I see some diameters are a little larger than 1.290", not sure now much clearance there is for a slightly larger diameter.

JakeFusion

iTrader: (7)

Seat pressure matters more to be honest for control of the valve when it snaps shut to keep it from bouncing.

I'd aim for 150/380 with those lobes, because they really aren't that soft. Only thing close is the PAC-1219X. You can shim it to get pressures up.

jmilz28

iTrader: (13)

I hit 465/446 (SAE corrected) with a stock LS3 and a 227/243 cam a few years back. This was with ARH 1 7/8 long tubes, cats, and an SLP dual dual. MHO, your exhaust could use some opening up (more headers than cat back) but it's not ruining you. Looks like you're getting good advice from Tick, listen to it. For reference, this same car did 345/345 with a bolt on LS1 and the same exhaust on the same dyno.

DietCoke

iTrader: (18)

You're not doing math. Do math, and re-evaluate what you're trying to accomplish. Published open specs @ a given height are irrelevant. What you want is the open rate at YOUR expected height open and closed. Lets look at the lightest conical spring and assume your valve length and seat allow you to set it up at 1.8".

438 lb/in spring rate with a 136 lb static rate at rest on the seat @1.8" or 405 pounds open pressure at .610 lift, assuming you are getting all of that lift through the lifter (you aren't). They're probably just under 400 in reality, depending on how they are set up. The intake side would be incrementally lower proportional to lift.


If you arent over 450lbs pressure, you aren't even taxing the rockers or valve tips. Just my thoughts.

JimMueller

iTrader: (9)

Thank you for explaining that, I honestly don't know how to calculate such things. I've read some about swapping springs and measuring heights but the devil is in the details. I most likely would buy the replacement spring kit and pay someone local whom I trust to set it up per the recommended consensus (does that still happen around here?), but I'd like to get some hands on experience and learn how to do it myself also.

If after replacing the springs & pushrods the curve is still indicating a problem, then I guess it's the lifters. But at that point I'm more likely to replace the heads also since they have to come off anyway.

Speaking of pushrods, I have some spares from a prior LS1 motor, details below...are the lengths close enough to throw them in at the same time as the new springs?

Crane Cams, 3/8" OD, .100" orifice, wall thickness roughly .135", stamped as 7.400"
14x average 188.23mm (7.411") long
2x average 186.97mm (7.361") long
A section of each pushrod, ~10mm in length, is polished, it begins ~60mm from one end. The tips on the pushrods are also polished.

Two sample OEM LSx pushrods from cylinder #4 average 187.94mm (7.399") long
0 lash seems to indicate it wants a 185.26mm (7.293") long pushrod, +/- 1/8 turn of the adjuster
GM publication says LS7 lifters want 1.58mm of preload

So it would appear I want a pushrod with an overall length of 185.26mm+1.58mm(.60")=186.84mm (7.356"), but I've been running 187.94-185.26=2.68mm(.105") preload. I guess my question here is the side effects, if any, of running .100" vs .60" of preload on the LS7 lifters, assuming there's minimal chance that lifter wasn't absolutely on the base circle. The only thing I've read about this is that the .100" preload will be a little quieter, is that the only difference?

Is there any reason I cannot or should not replace the OEM pushrods with the Crane units mentioned above?
How can I determine if I have the necessary guide clearance (.010"-.015") and lifter bushing clearance (.015-.025") with the heads installed? I'm pretty sure I used the Cranes with the Caddy lifters in my old LS1.

188.23-185.26=2.97mm = .117" preload (14 Crane pushrods)
186.97-185.26=1.71mm = .067" preload (2 Crane pushrods)

Would the discrepancy in preload matter?

Edit: The cam order form I received from Patrick Guerra back in 2010 recommended PAC 1518 or Comp 26918's. The cam grind is listed as 13116R/13118R.

SoFla01SSLookinstok

Reading you get some MAP fluctuation, at high rpm, makes me think valve springs. Keep at it.

JimMueller

iTrader: (9)

Captured a long log over the weekend. VE and MAF are pretty accurate during PE.





Below, the vertical line in the graph represents 5500RPM. I previously logged FP and it didn't have any spikes in it. Didn't log ignition voltage this time because I couldn't find the parameter in the new scanner. IPW maxes out at 16.2ms, max MAF Hz is 11250 but it only reaches slightly under 9000Hz at 6500RPM in 4th gear.



I've read that a vacuum gauge will show weak valve springs. I'll break mine out and see what it reports.

http://www.tuneruniversity.com/blog/...-vacuum-gauge/