caci

I recently installed a rebuilt engine in my 94 Z. After carefully breaking it in & changing the oil at about 1100 miles, it has great oil pressure, starts right up but does not seem to run as good as original engine.
This is a Jasper "stock" engine with 3 year/100,000 mile warranty. If you want to berate me for the Jasper - go ahead, PM me.

You may have seen previous posts from me, looking for help to get my car back on the road after a 13 year hiatus.
Thanks to GaryDoug & Injuneer for all of their help with Scan9495. After chasing all of the SES Codes and replacing most of the engine management parts, I was rewarded with an engine that dyno'd higher than it had previously in 2009.
I posted my dyno results, hoping to get some input ( "great", "that's BS" "sounds high", etc.). However, I received no replies.

"In 2009: Engine only = 301 hp/328tq, 100 shot nitrous = 404hp/450tq. (nitrous removed for "resurrection 2023"
Today (9/11/2023), 4 pulls (no printouts - monitor screenshots ONLY) 77 degrees, 60% humidity.
1st pull = 349.9hp, no torque displayed. Warm engine, hood closed, fan blowing on front of car.
2nd pull = 336.6hp, 350-ish peak torque, engine heating up, hood closed.
3rd pull = 335.7hp, 350 torque, engine getting hotter, hood closed.
4th pull = 345.9hp, 360 torque (pink graph) engine very warm, hood open.
It really felt like the car is running better than when I last drove it in 2009 and the dyno numbers seem to support that."

These are the powertrain mods, as of 2009:
PCM Tune (fuel & timing, redline 6000-6100, fans @ 160 degrees)
160 thermostat
SLP Shorty Headers
SLP Loud Mouth (cat retained)
Throttle coolant bypass
BBK 58mm Throttle Body
LS Injectors 0280155931 Bosch
LT4 Knock Module
1.6x Comp Cams Pro Magnum Roller Rockers

To get the car back on the road in August 2023, we replaced the following:
O2's
MAP (Delco Gold)
MAF (Delco Gold)
ICM (Delco)
EGR Solenoid/Valve
VSS (last, nagging SES)
Injector Connection serviced/tested LS Injectors

We also replaced:
Fuel Tank, Pump/Sending Unit, Filter and Lines
Starter
Alternator
A/C Compressor
1 Cooling Fan
All coolant/heater hoses.
Ditched K&N Gauze for Paper Filter
Installed SLP "Muffler" - removed "Resonator"

Unfortunately, I lost OIL PRESSURE at an HPDE @ Motorsports Ranch Cresson.
Self-inflicted disaster, as I had left the valve covers loose from trying to diagnose my "engine miss" from 2009.
Squirrels/rats used my intake ad a dining room table and acorn/pecan hulls worked their way under the loose valve covers, clogging the Oil Pump Pickup.

Budget constraints dictated the economical Jasper (my mechanic used them for gas & diesel, as well as transmissions).

Upon installation of the rebuilt engine, we deleted A.I.R and replaced the 2nd cooling fan.
I am running 1.5x stamped rocker arms.
I also deleted the oil cooler/heater. It had nut hulls in it and my research indicated that it is of little benefit as a cooler.
Proper "bypass" hose was added.

Engine feels just "OK".
May 7, 2024 I took it back to Alamo Motorsports in Arlington, TX for dyno.
Much lower HP/TQ than Sept. 2023
Average 275HP & 325 lbs ft for the Jasper engine, compared to 346/360 for the original engine.

Owner/dyno operator, Brice Yingling, asked "what happened, it ran so good before?"
He overlayed 1 of the 4 pulls from 2023 with the 3 pulls we just completed.
NEW ENGINE peaks at about 5000rpm, and appears to be as strong as the OLD ENGINE, up to about 3300rpm. Beyond 3300rpm, much lower Horsepower AND Torque (torque purposely omitted for simplicity on 3rd graph)
Brice's opinion was that it could be the cam profile/cam timing.


September 11,2023 Old/Original engine,3 pulls ('ROAD SPEED = TO 5800-6000RPM)





New Engine, 3 pulls (May 7,2024) overlayed with Old Engine







To determine if this might be something other than an engine problem, I've been in contact with Injuneer and he asked me to data log, per his test procedure. I t took a couple of tries, as I experienced a lot of interference, resulting in blank rows of data.
I thought this could be due to shielding of the DIY cable that I made. A friend suggested that I reboot my notebook and close any open apps/programs, as thjey could be competing with the USB port.
That seemed to work -I haven't looked at all 5000 lines of data, but don't see any blanks.
Injuneer has noted that this looks a lot like a constricted intake path but I have checked it from the intake to the air inlet, behind the driver's headlight (stock, NO CAI).
I've also removed the cat, with no change.

Here is a simpler, easier to read graph of the OLD engine (Green) vs. the NEW engine (Red).




After contacting Jasper the day after the May 7, 2024 dyno runs, the possibility of an engine "issue" was discussed, with the much lower horsepower figures. The Representative told me that compression, vacuum & cam could be tested (they could give me a "test" procedure for the camshaft). At that time, I told him that I would confirm there there were no other conditions causing the lower HP output.
Again, after checking the intake path, fuel pressure, even removing the catalytic convertor - same results (data-log wise).

I have not performed a compression check, as the lower RPM dyno numbers do not indicate an issue. I have measured the camshaft lift, at the lobe and with Intake @ .450" & Exhaust @ .468", the camshaft indicate proper lift (extrapolated for 1.5x rocker arms duration, overlap - cam timing are in question).

My mechanic spoke with Jasper yesterday (same customer service rep.) They discussed that we are concerned that we have a defective engine and, again, it was recommended that we check compression & vacuum (although, Jasper "spin" tested the motor for compression & oil pressure AND we have not checked...)

"Simple" HP comparison jpeg (sharper) was emailed, along with my narrative of performance mods were to be supplied this morning. He called back immediately, stating that they were going to do nothing, as the Horsepower figures are in line with factory specs. (no consideration given for comparison to old engine and performance mods).

When Kevin (my mechanic) spoke with him yesterday, the Representative for Jasper talked about how HE was a gearhead and how camshafts affected the performance of engines.
However, today, Kevin said his tone and demeanor changed 180 degrees, as if he was told to tell us to "pound sand".
I guess I see how they can give us the cop-out answer, as there is peak HP of 275 on the dyno sheet. However, at up to almost 100hp difference at a given RPM, there's no doubt an issue.

Any input concerning suggestions of what the problem could be, INCLUDING CAMSHAFT, would be appreciated.



Thanks,
Chris
214-762-2910 (if I don't answer, I will call back)

JakeRobb

Unfortunately, there’s just no way for us to know what’s wrong. I sincerely doubt that Jasper’s camshaft is out of spec, although that’s possible. It’d be hard to know for sure; you’d probably need to find a shop with a Cam Doctor and have them measure the old cam (do you still have it?) and the new one. You could also just swap the cams, assuming the old one is in good shape.

Were you the original owner of the car? Could a previous owner have installed an LT4 “hot cam” or something?

Are the heads identical? My intuition says that if the power curve is identical until you get into the high RPMs, that’s a head problem, not a cam problem. This reman engine might have a subpar set of valve springs, causing valve float at high RPM.

caci

JakeRobb,

Thanks for replying. Can I assume that you believe this is all mechanical and NOT an Engine Management issue?

1. Original cam gone - core engine exchange to Jasper.
2. I am the original owner - factory '94 LT1 cam never changed.
3. Heads - it never occurred for me to check. However, I have photos of my Old engine and the Part Numbers appear to match "10128374" . Photo of New head is a little tight...

Original head (1.6 CC Magnum Rockers)



New head - part number "clipped" but, looks like the same.




"Cam Doctor"? Intriguing - I'm curious how I can verify this cam, without removing it. In my already super-long post, when I first spoke with Jasper, he said to check my "cam position sensor", not realizing this is a 30-year old car. I'm supposing I'll need to mount a degree wheel, determine TDC and go from there, if I want to determine the Duration and Lobe Separation.

This is looking like maximum suckage - all roads seem to lead to major work -pulling cam OR heads (I guess valve springs could be removed, tested, changed in-car?).

Thanks,

Chris

Chimera96

Well Jasper is a budget rebuild shop using less than A list parts. Do they provide a build sheet showing compression and head gasket thickness?

Thinking compression is low.

caci

Would that fall in line with the hp/torque curve?

We are seeking a build sheet. The intake surface of the heads looked to have been freshly machined - perhaps the cylinder-side was machined as well?

Is there “overhang”, relative to the block - maybe I can look with a mirror?

Most of the compression “PSI specs” that I can find, focus on variance, rather than a hard number/range.

Ironically, if it DOES have a shorter duration cam, it will probably post a little higher compression with “4 compression cycles @ cranking speed” (vs. correct, higher duration/overlap cam).

Thanks!
Chris

Chimera96

A stock LT1(350 CI) aluminum head was 10.5:1 compression. You confirmed your Jasper is a "327" (casting #10125327) cast block and not the L99 265hp LT1 (casting #10168588)?

caci

Unless they are fibbing, I paid $50 for a 4-bolt 'Vette block.
Very sure that it is (always chuckle when I see "327" cast into the side of a 350ci engine..

Chimera96

look on side of block.

we can only guess possibilities why your Jasper motor is low on power, What is quench, what is head gasket thickness, rings gapped right, cam used, etc, etc

Injuneer

I think you need to post the overlay of the torque curves for the new Jasper engine and the 2023 dyno (need to correct date in your post September 11,2024 Old/Original engine,3 pulls).

That shows the major difference that to me points to the possibility Jasper may have put a B-Body cam in it. And/or maybe the didn’t install the cam indexed correctly.

And as I noted, the “outlier” is not the current Jasper engine vs. the 2023 dyno results. The outlier is the 2023 results. How did the engine gain 34 to 48 rear wheel HP over the 2009 number, with virtually no changes to the modifications (replacing sensors would not account for differences)? How did the 2023 dynos reach 6,400 RPM, when you indicated the rev limit was increased to 6,100-6,200 RPM in the tune way back in the earliest 2009 pulls?

caci

Fred,

Torque Overlay means another trip to Alamo - I can see the diff - see cropped photo below.
(Graph "1" date corrected.)

Not sure about RPM anomaly - I've recently run the car to the "limiter" while data logging AND have seen as much as 6200-6400 rpm through 1st & 2nd gears (on scan).
Those are New Engine pulls at the higher RPM
Also the RPM discrepancy could be a "shift" in the overlay, due to the fact that he dyno'd "Road Speed" vs "RPM" on my visit in Sept. '23. The overlay/merge may contain that error.
However, regardless of redline, the fact remains that power falls off at around 5000rpm. ( I know, you know that)

Regarding the jump in power from 2009 to 2023, I agree, that seems suspicious. Might the K&N (over-oiled?) could have caused this (switched to paper in 2023)?

I did measure the lobe lift on #1 I & E, direct from the pushrods = .300" & .312" (gross = .450" & .468")
I agree with you that this is acting like a "truck" cam, but can find no B-body specs with those lifts.
We are requesting a Build Sheet but, I'm not hopeful that we'll get honest answers, as they seem to be stonewalling at this point.

Thanks for all of your help.
BTW, were you ever able to examine my Scan, to rule out Engine Management issues?

Chris

Torque Overlay

Chimera96

OP, do you have dyno pulls using the SAE smoothing function (1-5). The graphs would be WAY les jagged

The results would basically be the same, just wondering why dyno shop does not appear to use that setting.

I think you have a long wait to hear any valid build 411 from Jasper. Who knows what cam profile they used. Maybe just a SBC Elgin one size fits all replacement cam. If Jasper did the heads also, suspect the valve springs are sub par. Dyno graph with jagged lines more up top typically indicate valve springs giving up but your graph has what appears to show no smoothing function that would otherwise reveal a specific RPM breakup often associated with valve float. I assume you were at these pulls so you would hear any engine breakup at anytime during the pull. Failing fuel pressure during a pull will also cause quite pronounced misfire.

caci

Yes, I was there AND have driven 1300+ miles since installation. NO MISSING or roughness.

“IF” the springs are weak & allowing float, wouldn’t that be kind of violent?

Injuneer

You sent me a torque overlay. The Jasper engine made more torque than the 336 HP 2023 pull, up to about 3,000 RPM, then nosedive’s under the 336 HP pull. Can’t remember if it was an email or private message.

caci

Fred,

It was an email - it would have been the one attached.
I know its crowded but ,Green line is OLD ENGINE, other 3 (clustered together) are the NEW ENGINE..
You should be able to discern the 2 engines.

Thanks!


Old/New Torque (top line)

Injuneer

It was a sheet that showed torque for the 2023 pull (336.6) and the Jasper pull. Just torque, no HP. Same colors as you mention above. That's what I based my comments about the B-Body cam on.