Engine knock questions...........................

[Doubeleive]

Can you guys tell me if the hummer mounts are configured the same way? They don't make the engine sit higher or anything right?

I'm guessing it's just a different material they used to make them stiffer.

Man, I'm having trouble finding them anywhere affordable. I'll keep searching.

Have any of you tried these? Saw them in another thread.

KEIN Engine Mount kit for GMT900 | GM platform | 2007-2014

KEIN reinforced engine mount kit for GMT900 Engines - 2 pcs. (Left & Right) • X2+X2 Quality molded high density silent blocks (inserted in the support) Bolts with a strength of approximately 50 kN.

risingtuning.com

this it the correct one and it works on either side, fitment is identical
usually it's a toss up between amazon and rock auto for the best price

Amazon.com

 

[mikez71]

Though not necessarily your issue, that looks like more movement than I would want or expect...
Especially with two bushings per mount. I'm curious what durometer (color) bushing did you get?

H3 mounts are like a plate steel/rubber sandwich, so it has more surface area against the bushing than just the profile of a bolt.
And it's flat, so not squishing the rubber like shock eyelet bushings..

 

[builds4christ]

so when I had my old broken stock mount apart, it had a hard limit to them, so when the rubber breaks, it's basically metal on metal, that will definitely show up on the knock. I'd guess you. can hit the same hard stop with enough hp and a non broken mount.

you have a boosted car, and a Procharger one. ain't nothing cheap about any of it. you need good mounts, the h2 might work, those poly ones should too and probably what I'd go with for boosted truck, where vibration shouldn't really be a consideration.


as for if your knock is real, the old school tests are reading spark plugs, I know this gets pricey and difficult replacing plugs often if a shop is doing it, so hopefully you're able to. go with ngk standard plugs with boosted or nitrous engines(I forget the common ls used plug, tr55 or something) . save the Platinum or iridium plugs for engines that are unmodified that don't get maintenance often. a heat range or 2 cooler, you'll put new plugs in it. do a pull, say drag strip. cut the engine off at the end of a pull and coast off the track. then pull the plugs and look for knock. it will be speckles the white ceramic(check youtube for plug reading videos) . if it's clean, it's mostly likely false knock.

the other old school test is if you run 93 now, find some 100 octane unleaded, put in say 10gal on a empty tank. and then do a log and see if knock goes away or stays the same. octane will only effect real knock.


I had a old D1 Procharger on a sbc forever ago when they first came out and man, it was a hassle. they might have gotten better. but back then a vortec ran like 8lbs without an intercooler and was rock solid for everyone. I wanted the intercoolered 15lbs procharger. and it kicked my butt(not enough money or knowledge). after a few motors and different operating systems. it basically cost me that car. it sat broken till I just sold it off for scrap prices. going fast takes a lot of money to do correctly. I just didn't have it, and these days I don't have the time for the hassle. I say that just to say, what's the intake Temps look like? can you lower the boost and make it more reliable and enjoyable? all things I didn't do back in the day and wish I had. I miss that car. should have left it heads cam and nitrous.

good luck man, I feel your frustration in my soul

I really appreciate your info brother.

I will try the octane test, since it seems the easiest for now.

I wouldn't mind ditching the charger, but it'll take me a bit to revert to stock too. I got the truck this way and don't have any of the og parts.

It's supposed to make like 7 or 8 lbs. It's their bare bones procharger kit.

I'm thinking I may just go with the poly mounts I linked. I would love the h2 mounts, but dang it if I can afford $600 right now.

I'll get back with y'all when I can fill it up with some better gas.

Annoyingly, I had a vortec on my 2001 Vette running crappy 91 octane in Cali without any issue. Ran like a champ pushing almost 550 Crank.

@mikez71 oh I haven't put any in yet. I replaced the stock ones with cheap Amazon stock ones 3 months ago. I made a big mistake especially with how much of a hassle it was to swap them out!

 

[mikez71]

In April of 22,
Changed both motor mounts w/Hummer mounts (2), GM# 25847739, $100 ea

Changed tranny mount, GM# 15840278, $41

I Changed all four O2 sensors with 2 new GM Genuine # 213-3533, $58ea, & 2GM Genuine # 213-3538, $53ea from amazon

Changed knock sensors, two# 213-1576, $11 ea

Everything is cheaper/same price currently, EXCEPT the H3 mounts!

 

[mikez71]

@mikez71 oh I haven't put any in yet. I replaced the stock ones with cheap Amazon stock ones 3 months ago. I made a big mistake especially with how much of a hassle it was to swap them out!

That's it! I think new mounts will do the trick..

 

[hagar]

What year and engine is it, and how many miles on the truck?
Procharger set ups are extremely easy to keep out of knock the way they build power compared to a screw charger or turbo. On 8 pounds, as long as the air to fuel is in the 11s, and the timing is below 13 degrees of timing at peak rpm, there should be no chance of knock on quality fuel.
Have you tried a new fuel source? I have seen multiple bad tanks of fuel come from the same gas station before.

 

[builds4christ]

What year and engine is it, and how many miles on the truck?
Procharger set ups are extremely easy to keep out of knock the way they build power compared to a screw charger or turbo. On 8 pounds, as long as the air to fuel is in the 11s, and the timing is below 13 degrees of timing at peak rpm, there should be no chance of knock on quality fuel.
Have you tried a new fuel source? I have seen multiple bad tanks of fuel come from the same gas station before.

@mikez71 man I'm hoping! And yeah wth on those hummer mounts!? I'll buy one, scan it and 3d print the other one .

Yessir, I've tried multiple gas stations. It's an 08 with an L92. It's got roughly 193k on it.

Dang it though! When the tuner gave me his initial tune, it ran like a beast! But since he's had to reduce timing on three tunes until he told me there's something unsual going on and that I should check for things hitting the chassis.

With the latest tune, it's back to feeling like a stock L92, rather than a boosted one.

 

[Joseph Garcia]

Let's be clear folks on the Hummer motor mounts mod. I've seen posts here stating both H2 and H3 motor mounts. The correct Hummer motor mounts for the LS motor is H3 motor mounts.

I run the H3 motor mounts, and I do not notice any additional vibration, but I'm not looking for a vibration-free truck, so I am not the best to assess that criteria.

The H3 motor mounts have worked great for me, but as @donjetman posted above, make sure that your transmission mounts are in good shape, as well as the front differential mounts. I chased a clunk for a while, but eventually found that my front differential mounts were toast.

 

[hagar]

@mikez71 man I'm hoping! And yeah wth on those hummer mounts!? I'll buy one, scan it and 3d print the other one .

Yessir, I've tried multiple gas stations. It's an 08 with an L92. It's got roughly 193k on it.

Dang it though! When the tuner gave me his initial tune, it ran like a beast! But since he's had to reduce timing on three tunes until he told me there's something unsual going on and that I should check for things hitting the chassis.

With the latest tune, it's back to feeling like a stock L92, rather than a boosted one.

Any chance you have noticed the procharger getting louder lately? Does the truck have headers? If it has headers, does it have the stage 8 locking header bolts? I have seen many a false knock caused by those things.

 

[builds4christ]

@hagar Not louder per se, but she's a bit loud. Not grinding loud, mind you.

I don't know if it's ever been rebuilt though. I DO know it's been installed a very long time.

It does have headers, but I'm not sure what type of bolts. How will I know? I replaced the collector bolts because they had rusted up. There are no spot marks at the header/head interface either.

 

[hagar]

@hagar Not louder per se, but she's a bit loud. Not grinding loud, mind you.

I don't know if it's ever been rebuilt though. I DO know it's been installed a very long time.

It does have headers, but I'm not sure what type of bolts. How will I know? I replaced the collector bolts because they had rusted up. There are no spot marks at the header/head interface either.

They will have bolts with little clips over top of them that keep the bolts from backing off. They create a perfect frequency for knock sensors to feed on. I have also seen broken exhaust baffles and clapped out cats create knock frequencies. I also always take off those stock metal spark plug boots with headers, they can rattle and give false knock.

 

[builds4christ]

They will have bolts with little clips over top of them that keep the bolts from backing off. They create a perfect frequency for knock sensors to feed on. I have also seen broken exhaust baffles and clapped out cats create knock frequencies. I also always take off those stock metal spark plug boots with headers, they can rattle and give false knock.

Copy thank you for those tips!

I took the metal sleeves off as well. Mine doesn't have cats, but it does have some sort of resonator on each side.

 

[hagar]

Copy thank you for those tips!

I took the metal sleeves off as well. Mine doesn't have cats, but it does have some sort of resonator on each side.

I would be happy to help you if you ever go the route of getting your own hp tuners cable. Unfortunately its hard to know many things, without seeing the data the engine is seeing.
I tuned a built engine challenger a couple weeks ago with an all new engine and d1 procharger. It never came close to being able to run the stock knock sensor tuning because of the combo, so it needed fairly heavy sensitivity adjustments.
Once you verify it is false knock for sure ( best method is to pull timing and see if the knock retard stays the same,) or if it gets a little weird feeling that it might be real knock, draining the tank and putting in some 98 unleaded, even 20 liters will be enough if the tank is almost dry.

Obviously it would be ideal to figure out why it is doing it now, and wasn't before... but sometimes things just start lining up that cause frequency problems. Could be the charger, could be an exhaust leak, could be engine mounts like you guys have been talking, could even be a bolt a mechanic dropped and is rattling. Sometimes there is no figuring it out, and you need to tune for it.

 

[hagar]

Sorry, one more thing. I would have your tuner do a crank relearn procedure on it for sh×ts next time it is there. With the mileage and vintage of the truck, your stock chain tensioner is 90 percent for sure laying in your oil pan in chunks by now.

I have seen a few trucks get enough chain slack/stretch to start giving misfires not because of a true misfire event, but because the cam to crank timing is off a bit and throws off the algorithm.

 

[swathdiver]

Hummer mounts are solid. Stock mounts are fluid filled for vibration damping. We can feel a little extra vibration at idle but do not notice it while driving. They appear smaller as they are but dimensionally bolt right up without issue.