[PRAY]

The procharger guys have mentioned it in multiple threads. I will see if I can get them to chime in here.

[ProCharger]

Originally Posted by PRAY

Just be careful with the long highway pulls or half mile events with FI. Procharger has been saying for a while that these stock short blocks have extremely tight ring gaps and have been popping on long boosted runs. Even they don't recommend it and I say good on them for bringing honesty to the forefront.

Someone said to point to "links" about his...
Well, I don't have any links, I just have the LT1 motors I have been around since the end of 2013...
If you ask shops such as Cunningham motorsports, Vengeance, CBI, RPM, etc. you will get the same answer about one of the "weak spots" of these engines.

Calling it a "weak spot" is really unfair to GM, because its not "weak" nor is it built "wrong".... it's just that the ring gaps are not ideal for high HP or boost.

These LT1 engines are designed to pass the crazy tight emissions testing that is now in place. Which is drastically different then it was 10 years ago. And with that in mind these LT engines have some of the tightest ring gaps I have personally ever seen.

Not only are the gaps very very very tight. There is an inconsistency to them, and that inconsistency is why "some live" and "some don't" when it comes to big power and long highway pulls. (even if the cars are tuned the same, and have the same modifications)

EXAMPLE: When a guy takes a "junk yard" LS motor and goes to make big power with it, one of the first things they do is open up the ring gaps... since all it takes is the time to take the motor apart,...file the rings to say .020-.028 gap (depending on power level, bore, and acceptable blow by) Once that is done, the chances of the rings "butting" is pretty much eliminated, and the pistons live a long and happy life. (until 25+ psi of boost is shoved in them. lololol. ) And even then many live a long long time.

THE LAST LT1 that I took apart to inspect had a factory ring gap of .008 on one slug, .009 on the next, and .012 on the remaining (6) slugs. Those two "tight" holes wouldn't survive long duration highway pulls no matter how "safe" the tune is. Thermo expansion would put an end to that fun in a hurry.


So there are a couple things to remember here.....

1) 1/8th mile, and 1/4 mile races are far far less stressful
2) Thankfully both a "drop in piston" and a "Drop in Piston/Rod" packages exist
3) If the piston does break, it usually doesn't hurt the block or anything.
4) With normal driving, spirited driving, 1/4 mile or less racing its pretty unheard of to break an LT1.


So I guess if you are doing something like a camshaft swap, and want to have a bit of a "peice of mind" do one of the following.....

1) pull the pistons out and re-gap the rings
2) throw a set of "drop in" forged pistons in there.

I only say that, since if you are doing a camshaft, you got like 90% of the motor apart anyways. LOL.



If you aren't doing a cam swap, just be safe with her, and enjoy the fun.



SIDE NOTE:
I have had someone say "well a CTSV can do it, why can't I"....well, for a couple reasons.
Engines like the CTSV (LSA), the LT4, Hellcat, 2003/2004 Cobra, Boss302, etc.

Are all forged motors, and (3) of the four I listed above were designed for BOOST!
So they have ring gaps to handle boost, they have pistons designed for boost (and heat) plus other items.

Those engines are like beer mugs... to the LT1 being a wine glass.
The will both hold water... but bang them together a few times and tell me which one lives.

[GuywithL86]

Originally Posted by oldman

Agree on drivetrain. On engine, it would be my opinion that the slight increase in fuel cut say from 6600 to 6800 and how much time a DD will actually be in that range. VS a supercharger always turning and most time adding a little boost... I think the nod to which can go 100K, 150K and 200K would favor reasonable NA.

I feel all modern engines have thin rings and high ring lands for smog and MPG, this make for a weak piston. The failure mode on a LT1 is piston, either through wear via miles or destruction via boost. I'm decidedly on the side that reasonable NA is FAR more dependable vs boost on a 11.4 CR engine. Also the chamber pressure / torque does cause more side load between the piston and bore leading to more wear.

Hp for hp, torque is always safer than rpm. The stress of the increased combustion pressure pales in comparison to the stress of the rotating assembly spinning faster, even more true with pushrod engines.

If your talking about driving characteristics and that you'd be using more hp out of the supercharged motor on a daily basis, that's not really relevant as that depends on the user.

The major downfall of aftermarket forced induction is really it's more like an unlimited bottle of nitrous or kers. You can't use it continously for a long period and it creates a more unpredicatable power band. (Well you can if you take great lengths to improve cooling like a manufacturer would)

Thankfully you can use forced induction long enough to reach speeds deep into triple digits, so not much of an issue on the street.

Back in the 90's I had 8 gauges in 2 gauge pods, including oil temp, water temp, egt, and ait, crazy what happens after 10-15 seconds of boost.

[SomeGeoffGuy]

Great post from ProCharger. Thank you!

What do you guys think of the gapless rings with the sliding ring gap? (total Seal or similar brands).

-Geoff

[PRAY]

Originally Posted by ProCharger

Someone said to point to "links" about his...
Well, I don't have any links, I just have the LT1 motors I have been around since the end of 2013...
If you ask shops such as Cunningham motorsports, Vengeance, CBI, RPM, etc. you will get the same answer about one of the "weak spots" of these engines.

Calling it a "weak spot" is really unfair to GM, because its not "weak" nor is it built "wrong".... it's just that the ring gaps are not ideal for high HP or boost.

These LT1 engines are designed to pass the crazy tight emissions testing that is now in place. Which is drastically different then it was 10 years ago. And with that in mind these LT engines have some of the tightest ring gaps I have personally ever seen.

Not only are the gaps very very very tight. There is an inconsistency to them, and that inconsistency is why "some live" and "some don't" when it comes to big power and long highway pulls. (even if the cars are tuned the same, and have the same modifications)

EXAMPLE: When a guy takes a "junk yard" LS motor and goes to make big power with it, one of the first things they do is open up the ring gaps... since all it takes is the time to take the motor apart,...file the rings to say .020-.028 gap (depending on power level, bore, and acceptable blow by) Once that is done, the chances of the rings "butting" is pretty much eliminated, and the pistons live a long and happy life. (until 25+ psi of boost is shoved in them. lololol. ) And even then many live a long long time.

THE LAST LT1 that I took apart to inspect had a factory ring gap of .008 on one slug, .009 on the next, and .012 on the remaining (6) slugs. Those two "tight" holes wouldn't survive long duration highway pulls no matter how "safe" the tune is. Thermo expansion would put an end to that fun in a hurry.


So there are a couple things to remember here.....

1) 1/8th mile, and 1/4 mile races are far far less stressful
2) Thankfully both a "drop in piston" and a "Drop in Piston/Rod" packages exist
3) If the piston does break, it usually doesn't hurt the block or anything.
4) With normal driving, spirited driving, 1/4 mile or less racing its pretty unheard of to break an LT1.


So I guess if you are doing something like a camshaft swap, and want to have a bit of a "peice of mind" do one of the following.....

1) pull the pistons out and re-gap the rings
2) throw a set of "drop in" forged pistons in there.

I only say that, since if you are doing a camshaft, you got like 90% of the motor apart anyways. LOL.



If you aren't doing a cam swap, just be safe with her, and enjoy the fun.



SIDE NOTE:
I have had someone say "well a CTSV can do it, why can't I"....well, for a couple reasons.
Engines like the CTSV (LSA), the LT4, Hellcat, 2003/2004 Cobra, Boss302, etc.

Are all forged motors, and (3) of the four I listed above were designed for BOOST!
So they have ring gaps to handle boost, they have pistons designed for boost (and heat) plus other items.

Those engines are like beer mugs... to the LT1 being a wine glass.
The will both hold water... but bang them together a few times and tell me which one lives.

Thanks for posting up. Good information as always.

[RideZX6R]

Originally Posted by PRAY

Just be careful with the long highway pulls or half mile events with FI. Procharger has been saying for a while that these stock short blocks have extremely tight ring gaps and have been popping on long boosted runs. Even they don't recommend it and I say good on them for bringing honesty to the forefront.

Originally Posted by PRAY

Thanks for posting up. Good information as always.

Agreed on both fronts, I'm glad Procharger posted also.
It's another reason I'm considering heads cam over blower.

However if I do H/C - I'd be lying if I said I didn't consider nitrous too... which is going to be hard on the engine/affected by ring gap as well.

Originally Posted by F1FTY

Well researched and thought out.

It has me back at the GM hot cam and CNC heads, honestly. Not sure for track work if power above that will be effective out of turns.

I haven't bothered to look at this setup, for a lot of reasons... Main reason being, while it is a part you can purchase at a GM dealership, it doesn't carry a warranty.
If I'm going off-warranty... and paying the same money regardless, I'm gonna get the most power I can for my money (within reason - and within drivability constraints/preferences)

[oldman]

Originally Posted by SomeGeoffGuy

Great post from ProCharger. Thank you!

What do you guys think of the gapless rings with the sliding ring gap? (total Seal or similar brands).

-Geoff

On my rice rockets, I run gapless. I have no experience with gapless on a piston as big as a LT1 102mm, my pistons range from 81 mm to 86mm. there is a vedor here with a forged lower CR piston drop in (same weight as stock piston).... but in the end this is a $3000 port and small cam thread, DIY and that is going to be IMPOSSIBLE for a supercharger to replicate.

[oldman]

Originally Posted by GuywithL86

Hp for hp, torque is always safer than rpm. The stress of the increased combustion pressure pales in comparison to the stress of the rotating assembly spinning faster, even more true with pushrod engines.

A) it is completely and totally possible to gain a big increase in performance from $3000 worth of heads and cam at the stock fuel cut-off RPM 6600.

b) as I've already stated, the amount of time a DD spends from 6200 to 6600 fuel cut is minimal, meaning very little impact on long term reliability.

c) the only "safer" would come into questions is: would a 6800 RPM fuel cut lead to rod bolt failure. The general consensus is no. You may contend otherwise. I have no experience with a LT1 over the long haul with a 6800 RPM fuel cut.


Now on the supercharged counter point. The LT4 puts out approximately 560 WHP. The OEM, added forged pistons with associated ring package, more cooling, a new block made out of different material, new valves, way better fueling (list off the top of my head). Even at that I think it is debatable if a LT4 would last longer than a LT1 NA stock vs stock. Ergo, a LT1 with a supercharger tossed on is going to be decidedly less long-live with the same performance envelope over time.

a) I personally know LS1 failures due to piston / ring under boost.

b) I know of NO LS1 bottom end failure due to a NA build with 6800 RPM fuel cut. Outside of the know failures of putting it into the wrong gear and letting out the clutch. I've already noted LS1 failures due to high lift cams (valve springs, lifters, pushrods and rocker trunions).

So to argue that( reasonable RPM on a reasonable lift) cam is worst than boost, where there are KNOW failures, renders the theoretical point moot. Prima facie boost hurts engines... whatever the reason.

My experience ends with the LS1 (yes the 1997 to 1999 rod bolt was a problem).

Originally Posted by GuywithL86

If your talking about driving characteristics and that you'd be using more hp out of the supercharged motor on a daily basis, that's not really relevant as that depends on the user.

The major downfall of aftermarket forced induction is really it's more like an unlimited bottle of nitrous or kers. You can't use it continously for a long period and it creates a more unpredicatable power band. (Well you can if you take great lengths to improve cooling like a manufacturer would)

Thankfully you can use forced induction long enough to reach speeds deep into triple digits, so not much of an issue on the street.

Back in the 90's I had 8 gauges in 2 gauge pods, including oil temp, water temp, egt, and ait, crazy what happens after 10-15 seconds of boost.

Agree

[bigsapper]

Thanks Procharger for that post. Great information.

To clarify on my about "posting a link" (if it wasn't already clear), I wasn't calling anyone out for proof. I am genuinely and sincerely interested in reading more about this topic, if that is available. You've given some very interesting insight into an issue I had not heard (read) of before.

[wnta1ss]

Originally Posted by ProCharger

Someone said to point to "links" about his...
Well, I don't have any links, I just have the LT1 motors I have been around since the end of 2013...
If you ask shops such as Cunningham motorsports, Vengeance, CBI, RPM, etc. you will get the same answer about one of the "weak spots" of these engines.

Calling it a "weak spot" is really unfair to GM, because its not "weak" nor is it built "wrong".... it's just that the ring gaps are not ideal for high HP or boost.

Could you give some more information on what setups you've seen break in longer runs? Are you talking 700hp on boost? What about a basic ~8psi setup?

[F1FTY]

Originally Posted by RideZX6R

I haven't bothered to look at this setup, for a lot of reasons... Main reason being, while it is a part you can purchase at a GM dealership, it doesn't carry a warranty.
If I'm going off-warranty... and paying the same money regardless, I'm gonna get the most power I can for my money (within reason - and within drivability constraints/preferences)

Yeah, the warranty part doesn't impact my decision once you start talking heads and a cam. Just looking at the specs, expected output and the range of relative safe power output for the engine when being hammered during 20 minute sessions for an entire weekend.

[trueraiderfan17]

Originally Posted by JaxChris

I think the only concern in the LT1, at least from the Corvette owners, is the pistons. That powdered metal soup can just falls apart under the increased pressure of boosted applications or when peak RPM is raised too far.

Vengeance offering drop-in LT1 pistons is smart for those that don't want to tickle the boom fairy when they get above the 600-650 mark.

oldman, the article you linked to on the 624-536-13 is odd. Their numbers are not quite what you would expect. For an aggressive cam profile, even on the shortened graph, I would expect to see the "after" showing the lower RPM power moved to the right and a harder climb after 3200 up to the new redline. Also, is it just me, or do every image I see of/about conical springs look like they compress unevenly under the retainers and do not maintain a cone shape? Beehives stand straight up when installed and don't have a wavy profile like conical do. Maybe I'm paranoid, but it doesn't seem like the potential for increased lateral oscillation would be a good thing when you're increasing RPM.

I think for those looking to avoid boost the best combination for a daily driver would be:
624-524-13 Comp Cam XFI AFM (or similar)
Ported Intake Manifold
Ported Cylinder Heads
Ported Throttle Body
Rotofab Air Intake (Dry Filter w/o Sound Tube)
1 7/8 Headers (Those I've seen install 2" lose power unless boosted)
2nd Cat Delete (Maybe even scrap AFM valves)
Mid-Pipe
Flex Fuel Kit
E85/93 Tune
HP Tuners
Installation

An owner that strikes the right deals for his parts could probably get this done for 5500-6000 all-in and I think it would get close to 550hp/500tq (not to the wheels). If you wanted to add a lot more labor and parts to strip AFM and go for a bigger cam, then I think 600/525 is possible with a 50% bump to the price tag. Gas mileage will suffer on E85, but pump price will make up for the lower economy.

I could be totally wrong, but I think I'm very close on the numbers/prices.

I went with texas speed stage 3 cam,LME aftermarket ported heads with race valves, roto fab CAI, Hooker headers 1 7/8 with x pipe and all cat delete with factory npp, msd intake, ported throtelbody, (no e-85 yet don't want to mess with the lack of it around here right now) and a hp tuner and tuning plus labor and it is costing me about 13 grand give or take a couple hundred. I should be getting it back Monday Seems like it has taken forever for this process to happen. it needs to make 650 to make me 110% happy better not be below 625 or I will be a little disappointed.

[DFW1LE]

Originally Posted by trueraiderfan17

I went with texas speed stage 3 cam,LME aftermarket ported heads with race valves, roto fab CAI, Hooker headers 1 7/8 with x pipe and all cat delete with factory npp, msd intake, ported throtelbody, (no e-85 yet don't want to mess with the lack of it around here right now) and a hp tuner and tuning plus labor and it is costing me about 13 grand give or take a couple hundred. I should be getting it back Monday Seems like it has taken forever for this process to happen. it needs to make 650 to make me 110% happy better not be below 625 or I will be a little disappointed.

I hope you are talking at the crank.

[trueraiderfan17]

Originally Posted by DFW1LE

I hope you are talking at the crank.

no I was talking rear wheel hp. What are you thinking it may be? 600?

( of course I got all the other stuff like rods, trunion upgrade (sp) and all that garb just didn't want to list every single thing that came in the package)