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Anyone Busted a Stock L67 from too much power ?

22971 Views 20 Replies 8 Participants Last post by  10trigger
Hey L67 3800 Owners,

Not sure if this is the correct section to be posting but it seemed the most hardcore in the way of mod's so here I go ...

A bit of a brief intro from the land of Oz from FIT.

My name is Tony and I am the Technical Sales Director and S/C V6 Enthusiast at FIT Australia, as I'm sure some of you may know.

... without getting too caught up in introductions because I know this isn't the right section for it, I'd like to ask ...

Have any of you guys pushed the limits of the "Internally Standard" L67 ?

And if so what was the power at the wheels recording ?

I'm sure there's a few broken one's around the place, maybe for the wrong reasons, such as detonation, or general component failure or fatigue, but just wondering really ...

"Where is the limit for an internally standard L67" ?

We have our Internally Standard L67 Turbo Test Mule pushing 440rwhp (fwhp to you guys) and realising an 11.688 @ 121.78 mph down the 1/4 mile with a 1.976 60'ft time in a RWD Commodore that weighs 4000lbs !!

BTW - Hat's off to Scott Cook and Ed Morad ... legendary times !!
(and all you others that are achieving unbelievable results)

Anyone able to shed light on this topic/subject ?


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I ran out of fuel pump on my turbo L36 on a [email protected] run. I popped a piston, which is a common occurance among the boosted L36 and L67 crowd. I've heard of a few cases of thrown rods on L67's but none of them seemed to be from high hp, more than likely an engine defect. The bottom end of these engines are pretty damn bulletproof. But, I'm sure there will come a HP level at where the L67 just won't hold.
Thanks for the reply, sounds like you're doing quite well with your's to, there's an 11's pass just around the corner for you.

Yeh, it seems most of the broken one's over here are for silly things like crumby fuel or bad tuning, but no one really know's where the limit is. I know it's a bit of a "how long is a peice of string question" but we're just interested to see if anyone can shed some further light.

We have run 400+rwhp for the past 6 months with over 100 1/4 mile passes and still everything's ok.

We're very conservative with tuning, and have loaded plenty of fuel into the map for extra safety margin.

All the best with your future development and times.


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We're not too sure where the limit of the stock pistons and con rods is. Several people have hit 400+ WHP repeatedly and reliably with no problem on stock internals. I've run many 11 second passes over a year's period myself on a stock bottom end, my fastest (on that bottom end*) being [email protected] Obviously, the trick is to keep enough fuel in the motor. We do believe that the crank will hold until 800 crank horsepower. I hope to challenge that in the not too distant future.

* - I'm currently shaking the bugs out of a new setup including a racing block with forged pistons and rods.

Please keep us updated with your progress!

John, did u remove your balance shaft? If so, you didn't balance your bottom end since its all stock...am I right???
I removed the balance shaft on the new motor, and had it 50% balanced. The curent bottom end is not stock. On the old stock motor, the balance shaft was never removed.
... sorry John T that I'd missed the special mention to you as well, it was fairly late/early in the morning for us over here when posting, brain was a little tired ... but yes we've noticed your very impressive results, good work.

... we've done a couple of 400+whp passes and over 100 1/4mile passess with around 19 - 20psi boost and it's still holding together very well.

... we accidently ran 27psi boost by accident, someone had been messing with the boost controller ... luckily is was breaking out into wheelspin every time so it wasn't crazy loading the motor, and as soon as we found out we turned it down ... but that leads us to a related question ...

... how much psi have you seen the stock gaskets hold ... but then again this relates to how aggressive your timing map is, as well as air/fuel ratio's and resultant knock retard ... etc ... but as a general rule have you any stats ?


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No need to apologize Tonsta, I wasn't looing for any kind of mention. :)

As far as boost is concerned Scott has pushed 30 psi recently but as you know his motor internals are not stock. His turbo car always had a race motor since the day he built it. As far as the Boneville, I'm not sure at what point they switched to a race motor as well. I'm sure it was before they pushed 20 psi though. And I only pushed my previous stock bottom end to 19 or so. With my current setup I think I'm seeing about 22-23. That is 19 on just the blower, and the rest when the nitrous flows.

I'm not sure how much the stock gaskets will hold. Personally, I've only pushed 17 psi through them when they were stock. If I'm not mistaken, all the high power cars are now running the MLS gaskets. They seem to do much better. We've also found that timing kills head gaskets much quicker than boost does. If you keep timing reasonable and a healthy AFR gaskets last a lot longer. Some more data points for you. I used to run 25 degrees of advance on 18 psi of boost on just the blower. On 19 psi plus a small 60 shot I ran 21 degrees with no KR. I'm currently running a 90 shot with no KR. I've turned the timing down to 19 just to be safe.

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We're only running a very conservative 14* - 15* Worth of Timing and Rich Air/Fuel ratio's in the 11.8:1 range and pushing the 400+whp mark quite easily and reliably.

We think you definitely hit the "nail on the head" saying the gaskets become more fragile when timing is set at a higher commanded amount like 20* + degree's because we have found the knock sensors and auto-knock-retard can't act fast enough at High Hp High Load applications

Therefore the slightest Detonation will kill the gaskets very quickly because the auto-knock-retard safety mechanism can't react quick enough and edge limit tuning doesn't leave a lot of margin for error's.

In saying this we are talking stock heads, stock cam ... which yours is obviously not and the timing 20* + degrees you are running with the bigger M112 would be about right ... not that we are trying to tell you, I'm sure you are well in front of us and already well aware of this.

Cams and heads and more efficient blowers open up greater scope and opportunity for more agressive timing numbers at full load.

Do you run yours on pump fuel for racing or race gas ?


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because we have found the knock sensors and auto-knock-retard can't act fast enough at High Hp High Load applications
It's refreshing to hear that for a change. So many people don't understand that the way the KR mechanism works is by sampling detonation and then making a decision on just how much timing to pull to eliminate it, sampling again, and so forth

I think that part of the problem is the tone of the sound that characterizes detonation. I'm not 100% certain, but I believe that our knock sensors are tuned to 6KHz. That being the case, depending on the number of cycles that the DSPs have to sample before they "detect" detonation you can have many detonation events in a single cylinder before the PCM even knows it's there.

not that we are trying to tell you, I'm sure you are well in front of us and already well aware of this.
I certainly don't take that attitude and I hope you don't either. I think we can both learn a lot from each other.

As to your question on fuel, I race on unleaded race fuel. How about you guys?

And now I have to do my administrator's job. Tonsta please include your last name in your profile as is required by this forum's rules. :)

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johnt said:
It's refreshing to hear that for a change. So many people don't understand that the way the KR mechanism works is by sampling detonation and then making a decision on just how much timing to pull to eliminate it, sampling again, and so forth ...

... And now I have to do my administrator's job. Tonsta please include your last name in your profile as is required by this forum's rules. :)

Last Name ... Done ...

Yes, the KC (knock Counts) and AKR (Auto Knock Retard) are parameters that can be played with and set via. our Kalmaker Engine Management system.

There are variables called:

- BKR (Burst Knock Retard)
- KC (Knock Counts) and
- KIC (Knock Ignore Counts)
- MAXRTD (Max Knock Retard)
- KRD (Knock Recovery Delta)

as well as around 50 - 60 others, but these are the main one's.

Tweaking with the paramters allows you to electronically "Dull" the sensitivity of the sensors as they can be prone to a lot of valvetrain mechanical "False Knock" situations, where there is no knock but timing is removed anyway.

This "Psuedo Knock" is the main cause for a lot of power instantaneously lost when the AKR takes the fun our of the timing map.

You can switch it off completely, but that leaves you no safety.

Where it becomes difficult is determining how much to turn down the sensitivity before you end up in the danger zone.

We've tried getting carried away and you can hear the knock occuring before the computer decides to pull it out, because it then takes very savage knock to trigger the KR process.

The other problem, is even when you do leave it all as preset from the factory, and it isn't experiencing "false knock" but you are creating soo much power and it's happening soo quickly the AKR can't pull the timing out quick enough to pull up the spiraling detonation ... and you end up taking home the engine in a body bag ... !!

We haven't killed one yet and haven't heard of one dying in Australia, but most except Louie, really aren't pushing the engine's to the limit's yet. In time I'm sure there will inevitably be occurances.

Summary - There are a lot of paramters with regards to detonation and knock and when you're creating a lot of power it all happens so fast and there's little margin for error.

Hence why we have been conservative with our's. When we get the go ahead from Management to Kill the Egnine, we're going to video it on the Dyno and just keep turning up the boost until it drops it's guts on the dyno floor.

We will tune it along the way, we're not sadist's, we are scientists ... but hey it will be fun at the same time :D

We'll let you know how it goes.

BTW: Yes it just runs regular pump gas, but of the highest quality and Octane you can get here which is 98+RON.

We are planning to experiment with race fuel in the "science experiment" above, and so on ...

Running pump gas and extreme tuning is quite dangerous as we have experienced variances in pump gas quality that could potentially damage a hard tuned engine, hence why we always remain conservative.

What quality (RON other other rating) do you guys have ?

Have you ever, or will you ever try race gas on yours ?

How come you haven't opted for an intercooler on the M112 ?



P.S. Good to see you guys are a good bunch of blokes and not arrogant know it all's who have little patience for the opinions of other's as what occurs in other forums ... they say you can only learn by listening ... !!
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Great info here, guys.

As for the octane rating, toward the east side of the US, the highest "pump gas" octane that can be found is 94, but 93 is the most common. If you go toward the west side of the country, typically the highest you can find is 91. What John was referring to is actually race gas, but it is unleaded, which obviously limits the octane rating. The most common unleaded race gas comes in 103 or 104, but I believe VP Racing Fuels makes some 109 unleaded. Since our O2 sensors are relatively expensive, we tend to stay away from the leaded race gas.

Also, John in fact does run an intercooler on his M112. ;)
Your engine management system sounds very sophisticated. We're not there yet. We're still on the stock PCM, albeit we use HP Tuners for custom programming. It's a nice tool, but yours sounds like it considerably more flexible.

When we get the go ahead from Management to Kill the Egnine
It sounds like a pretty big operation. INTENSE does a lot of testing along the lines of what you're alluding to. As for myself though, I live 500 miles away from INTENSE so even though I'm on the team, for most purposes I'm on my own when it comes time to tune, test, race, etc. For me it's a good day if I can get one of my sons to come to the track and help me change tires. :) I'm not complaining though. It's still a lot of fun.

Like Jason said, the race fuel I use is indeed unleaded. I prefer VP MS-109. It is 101/109 (I forget which is RON and which is MON) for an average of 105. I'd like to try 110 leaded but haven't yet. And yes, my MP112 is intercooled, although now with the nitrous I could probably just yank it and toss it to save weight. :)

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Thanks for clearing up the intercooling puzzle, I didn't see it in your signature ... but it's probably included in the "one or two other things" :D !!

It kind of makes sense now, was wondering how you could achieve those times, but then again in saying that, ... enough No2 will do the same !!

It's very interesting the developments you guys are making !!

With regards to the Unleaded vs. Race Unleaded issue, is it all available at the gas station, or do you buy it in 20ltr drums ... also do you always run race gas (expensive !!) or do you have 2 maps ... one for race gas, one for family man ?

Yes our Kalmaker system is very ellaborate. It takes you right into the heart of the Delco Factory Management. It's not piggy-back, nor is it "flash" driven, it's real-time engine management re-programming of the standard Factory Delco Computer ... just like a full aftermarket one, but with heaps more features, and no re-wiring required.

It's the "ducks-nuts" and we thank the Lord everyday to the guy that engineered the software. The representative for it tells me of all the enquiries many US L67 guys have made regarding the system, but unfortunately due to major differences in management computer it's not cross compatible.

You guys have got "head up display" and various other features controlled by your management computer, and it's of similar engineering to the LS1 computer - "flash" driven ... or so I'm told. I could be way off, and the questions have prbably be asked before, but check out the website and email him:


We have it listed on our site, and again get many enquiries regarding it's possible application for your computers, but we only have it listed as a favour for Kalmaker for supplying us with one for the Turbo Test Mule. I wish I could help you guys out and write software codes, but unfortunately that's not my qualification. Al Gibbs is the Kalmaker man to speak to.

How do you guys tune yours ?


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3800L67 said:
With regards to the Unleaded vs. Race Unleaded issue, is it all available at the gas station, or do you buy it in 20ltr drums ... also do you always run race gas (expensive !!) or do you have 2 maps ... one for race gas, one for family man ?
The unleaded 100/103/104 is available at a select few gas stations, but not very many. 110 leaded is more common to be found at Sunoco. The VP race fuel I'm pretty sure needs to be bought in drums (5 gal, 20 gal, 55 gal). Typically race gas is only run at the track.
Hi Tontsa...small world hey :D

Now this is all stuff I tried to find out in the SC forum with regard to timing and detonation without any real clear answers. I am the first to admit that I am not fluent in technical knowledge when it comes to engine management, but I have picked up a bit of basic knowledge over the past few months since playing with my L67, mostly through my tuner but also from careful trial and error.

I am running a TSI 'Tuning Solutions International' piggy back real time style ECU to manipulate timing and fuel via a laptop. I find that I can successfully run an extra 16 deg of timing on top of the factory timing, btw > what is full factory timing? To run the extra timing without detonation I MUST add Octane boost to my 98 RON fuel plus I also have water injection. It gets expensive to use Octane booster all the time so I run 2 Timing maps, one for STREET with only 12 deg of extra timing and one for STRIP. If I keep the timing set aggressively on just 98 RON fuel that is when I get detonation issues. It seems to come in suddenly and Tonsta the way you mentioned it as a BURST seems to describe it perfectly. Now this burst seems to come in at approx 5300-5500 rpm (when the blower with 3.25" pulley is at max revs) and just before a gear change. The TSI is supposed to not effect the standard knock control but it seems like the Delco just cant react quickly enough and by the time it has then the car has changed gear anyway!!

So what I really would like to know is...What is the stock igntion timing at WOT? So that I can really know how much total overall igntion advance I am using.

Now I fully understand that part of my problems, although manageable, are due to the fact that I am running a 3.25 pulley, NON intercooled at this stage and aggressive timing to find the limit. For my level of purely bolt on mods (internally stock) I am very satisfied with my results of 13.404 @ 101.47 but it has been pushed pretty hard to get there. That stage is behind me now with a complete new engine build-up started last week with tough internals and the current original L67 will be retired to the shed floor for a spare, hopefully not needed :)

So hopefully my 'simple' explanations make enough sense and curious what you guys think.
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Hello ravensuper6 - small world it is ... around the world and back again !!

I'm sure the guys here can ellaborate, but from our understanding the TSI intercept module you have piggy-backed into the existing Delco system "tricks" the timing and fuel outputs to achieve the desired effects of more/less timing and fuel.

For example:

- At 5,200rpm the Delco may be commanding 12* degrees of timing

The TSI is told to add 4* to make a total of 16* degrees of timing

- But if there is "knock detected" and the Delco pulls out 6* of timing, you're total timing after the TSI interceptor will be 10* degrees

... so you kind of end up back where you started.

There is no real "base" timing for the Delco, it's "interactive" and changing according to how much knock is detected. Generally if there is no knock detected timing is a "pathetic" 11* degree's at full load full boost.

If knock is detected this can be retarded as much as 14* making for a total timing of -3* degree's .. yes you read right -3* degree's, we're talking minus number's here and engine power drops substaintially. Muvro was experiencing this before his intercooler, running 2.6" 18psi pulley and pulling 168rwhp on the dyno, then after the intercooler with no tuning he was up to the 280+rwhp mark.

Timing get's hell retarded when boost is increased beyond 10psi with no intercooler because of high temperature and the stability limitations Premium 98RON Octane Unleaded . Running 12psi even with water injection will always be unstable as any variance in Octane will affect power substaintially and cause detonation issues as you have mentioned when you don't run Octane Booster.

When you have a cam and headwork things change because the increase in flow "bleeds" off boost. Eg: Super SS's car with a 13psi pulley only ever saw 8psi in the manifold after the cam install because the boost was being bled off. Remember boost is a measure of restriction, so free'ing up the congestion in flow by fitting a cam, free flowing headwork, extractors, exhaust, .. all bleed off boost.

So you may think you are running 13psi boost but in effect you are running 8psi and hence there will be less tendancy for detonation with head and cam packages than 13psi on it's own ... which will certainly detonate without Octane Booster.

But just because you are seeing less boost in the manifold, doesn't mean you will result in less power. In fact most of the time you will see a lot more power. Like Super SS gained 30rwhp from the cam and tuning upgrade.

It's quite a "Paradox" when you thing about it ... less boost but more power !!


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Thanks for that GR8 post there - GR8racingfool - very interesting stuff !!

It seems in both of the above instances there were external factors that caused the carnage ... incorrect machining, assembley, or flaws in the components themselves.

Looks like there still remains the mystery of exactly how much Hp can be tollerated by the Stock Engine assembely, but I suppose it will always be somewhat of an unknown as there will always be tuning, fuel, detonation, flaw's and other issue's that may occur when trying to extract the las inch of Hp from the stockie.

So far it looks like somewhere between 400rwhp and 500rwhp ?

I suppose the question could be somewhat re-phrased now to ...

"What's the most amount of rwhp (above 400rwhp) anyone has obtained from a stock L67 or L32 with whatever power adder's imaginable ... M112, Turbo, No2 ...


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That's going to be a hard number to get Tonsta, as most big power guys are running forged pistons. Also keep in mind that with a hypothetical set of engines, all at their limit before they break, the turbo will be able to put more power down to the ground since it presents less parasitic losses or load to the rotating assembly.

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