Procharged 6.0 v. Whippled 454

[durbo.jones]

I have a buddy who just bought a Procharger setup for his 07 RCLB 2500HD. How do you guys think my Whippled 454 will fair against it in normal truck duties? I am not talking hitting the drag strip and running the 1/4. I am talking about hooking 8000 LBS behind the trucks a seeing who out pulls who. I plan on trying to get him to give me a run to see what happens.

[PonyKiller87]

How big of a procharger? Is he intercooling? My guess is it will out perform your truck empty vs empty, but loaded I think you will still have the advantage, your truck will be making more power right off idle than his will and that where you really need it when towing.

[durbo.jones]

He is going to be running the intercooled D1 setup. I am looking into finding a longblock to rebuild (I don't want any down time with my truck) and set up for specifically for running the Whipple. I want to get a smaller pulley and up the boost closer to 10 lbs.

[Miles B]

I would have thought for towing you'd already tear him a new one.
All reports have a stock 454 beating a stock 6.0 for towing.
Centrifugals start making their boost well after you've pegged your boost gauge on a twin screw. Unless he likes towing at 3500rpm you've got more boost. Pulling that load off the line, his centrifugal doesn't help him much at all.
Straight line race he would have you though, I'd reckon.

[durbo.jones]

I have a feeling that off the line or on a long hill I would hold better. I am having a custom cam ground, swapping out to a smaller pulley, and setting up a Meth injection to keep the IAT down. I think that I should be able to hit well over 500 ft lbs of torque right around 3000 RPMs. Hopefully I will have all of this and the NV4500 swap done by April or so.

[chevy05]

I don't think you will have any problem I had a 05 with a 6.0 and know I have a 99 k3500 with the 454 and pulling the same loads same roads the 454 pulls with out even down shifting or even caring it is even there.

[Outlawz2004]

I think as far as speed and getting down the interstate, the 6.0 will do better. Stop and go pulling, I believe the 454 will do better because its power band is much lower. I love how people always say that an LS motor will be towing at 3500 rpm. The LS engines are more than capable of making plently low end power, and cruising down the highway singing along with a bunch of weight behind it, the whole time getting better fuel mileage. Side by side pulling same weight same distance, my money is on the procharged 6.0 getting it done before the 454.

[The Fiddle]

I think as far as speed and getting down the interstate, the 6.0 will do better. Stop and go pulling, I believe the 454 will do better because its power band is much lower. I love how people always say that an LS motor will be towing at 3500 rpm. The LS engines or more than capable of making plently low end power, and cruising down the highway singing along with a bunch of weight behind it, the whole time getting better fuel mileage. Side by side pulling same weight same distance, my money is on the procharged 6.0 getting it done before the 454.

Considering if the '07 is the current GMT900 platform then it will have the six speed auto as well, I'd have to agree.

Otherwise on a GMT800, I'd disagree.

[2500ak]

What gears does the truck with the 454 have?

I think it'll come down to gearing. If the 07 has the 6 spd and 4.10 gears it'll have a significantly lower first ratio than the truck with the 454.

The 4L80e has a tall first gear at around 2:1. The 6-speed has about a 4:1 first gear. More than enough to close the low-end performance gap inherent between big-blocks and small blocks. If the BB had the NV4500, that would be different.

[durbo.jones]

The 6.0 is in a 07 Classic (GMT-800) with a 4L80. The 454 is going to have a NV4500 within the next two months. I have everything for the NV4500 swap, I am not home to do it though. I am also running 4.10 gears. I am not sure what the 6.0 has.

[2500ak]

Then I'd say the 07 is still going to be faster unloaded, and get better mileage. It has smaller displacement, which it can supplement with boost. LS engines take to boost better than most.

The 454 will be a better truck for hauling. If traction is right have more initial acceleration, and obviously will be a lot more fun to drive because it's a manual.

That is my prediction.

[1998454]

I hope this race happens! My take on this is.... My truck has a 454 with headers, underdrive pulley, cai, and a hypertech. 4L80 and 4.10 gear. Best 0-60 run to date is 7.68 seconds in 4wd. Friends 06 6.0, cai and cat back system with auto and 4.10 gear 0-60 in 8.21. We have never raced, but if my math is correct i would win..lol. Now your truck is getting a cam swap and boost so I will assume if you both run equal pressures, you win. Assuming your shifting is on! I will also throw this out here...10 psi through a 7.4 is alot more air than 10 psi through 6.0 liters.

[Outlawz2004]

I hope this race happens! My take on this is.... My truck has a 454 with headers, underdrive pulley, cai, and a hypertech. 4L80 and 4.10 gear. Best 0-60 run to date is 7.68 seconds in 4wd. Friends 06 6.0, cai and cat back system with auto and 4.10 gear 0-60 in 8.21. We have never raced, but if my math is correct i would win..lol. Now your truck is getting a cam swap and boost so I will assume if you both run equal pressures, you win. Assuming your shifting is on! I will also throw this out here...10 psi through a 7.4 is alot more air than 10 psi through 6.0 liters.
I dont know how you figure 10psi into both engines will give more power in the 7.4L, the Ls engines respond so much better to boost. Combined with a slow shifting manual, I believe the 6.0 wins in most situations but not all. Like I said before, it really depends on if your hauling inner city or on the open road. I would take the 6.0 if heading out cross country with a load, but if I was pulling a heavy load for short distance I would rather have the 454.

[2500ak]

I didn't say that. I merely stated that it requires more air volume to maintain 10 psi on a 7.4 than a 6.0. I thought that would be common knowledge. If it weren't then we would be taking turbos off of hondas and running them on a V8. One would assume that more air requires more fuel to maintain correct afr. And i agree, the 6.0 should make more power for several reasons, aluminum heads, better ecm and just higher tech in general. But the fact is, in the example i provided, the 6.0 just doesn't have it! Not only is my truck .5 second faster to 60, if we keep going it just gets worse for him. My truck also weighs 500 pounds more. I think on this topic with the boosted engines it's anyones guess. The 6.0 had better beat the old outdated standard trans big block...I just wouldn't count on it. I certainly hope the race happens so we all know...most here just post "what if" and it never ends.


Looking at it in terms of boost is approaching the problem of making power from the wrong angle.

Boost is a measure of resistance. If the 7.4L engine has significantly lower durations ground into it's camshaft, or worse flow, into and out of, it's cylinders for it's given displacement it is entirely possible that an engine with 1.4L less displacement could take in a larger volume of air than a 454, with a smaller amount of pressure in the manifold.

My money is still on the 6.0L. It's a low compression engine that likes to rev, and has been proven to be resistant to compression related knock. A good pairing for that type of forced induction.

Now that I know the gears are more or less equal for the time being, I suspect it may come down to the cam used in the 454 engine. A more radical grind could tip the scales.

Is the fuel system stock on the 7.4L? I think they were still using that CSFI injection before 99. How much power can those setups actually feed?

[V3NOM GTO]

Looking at it in terms of boost is approaching the problem of making power from the wrong angle.

Boost is a measure of resistance. If the 7.4L engine has significantly lower durations ground into it's camshaft, or worse flow, into and out of, it's cylinders for it's given displacement it is entirely possible that an engine with 1.4L less displacement could take in a larger volume of air than a 454, with a smaller amount of pressure in the manifold.

My money is still on the 6.0L. It's a low compression engine that likes to rev, and has been proven to be resistant to compression related knock. A good pairing for that type of forced induction.

Now that I know the gears are more or less equal for the time being, I suspect it may come down to the cam used in the 454 engine. A more radical grind could tip the scales.

Is the fuel system stock on the 7.4L? I think they were still using that CSFI injection before 99. How much power can those setups actually feed?

You're on the right track but you missed just a little. Boost is a measure of resistance, but you can't remember what the important part is, FLOW. So more boost with less flow is not better than less boost and more flow. Cuz we all know that internal combustion engines are just big air pumps, the more air and fuel you get into the cylinder the more power it makes. Doesn't matter how hard your pushing, if you got it there by Condensing the air (N20), just how much gets into the cylinder. The 6.0 will make more power because it flows more to begin with. Mostly because of the head design. The oval ports made after 1975 are garbage. The vortecs are a far sight better than the peanut ports but still garbage. It's also a ridiculously low compression ration of about 8.1:1 some have been reported as low as high 7's. Where the Lq9 is around 10:1 and the Lq4 is 9.1:1 not to mention the Combustion Chamber is way more efficient giving you a much better burn. The 6.0 with cam and intake will put 400 to the wheels. The 454 makes probably 215 RWHP from the factory :( . Now do a head swap and some serious tuning and the playing field just got leveled. Short of that the LS wins, not b/c the procharger is better than the whipple, because the LS flows more. I say all this with a broken heart as I have a 90 TBI 454 and a whipple, but with heads/cam/intake/Tuning Ability coming this spring I should level the playing field a little.

Sorry for the novel.

[2500ak]

You come into the big block section to argue against it, and an you don't know enough about the the 454 to know what you're arguing against. The 454 was never CSFI, it went from TBI straight to MPFI.

Are we really going to segregate the forum like that? I don't go into any section, I do what I assume 99.9% of everyone else does, press the new posts link and click the ones relative to my interests.

I am genuinely interested to know which one will outrun the other. If the OP didn't want anyone to argue against it he wouldn't have asked the question. The post simply would have been titled "my truck can outrun a Procharged 6.0L truck" and left it at that.

[1998454]

The compression on a 454 vortec is 9.0-1. you are listing low compressions found on the tbi truck. But from a forced induction point i would rather have 8-1.
You're on the right track but you missed just a little. Boost is a measure of resistance, but you can't remember what the important part is, FLOW. So more boost with less flow is not better than less boost and more flow. Cuz we all know that internal combustion engines are just big air pumps, the more air and fuel you get into the cylinder the more power it makes. Doesn't matter how hard your pushing, if you got it there by Condensing the air (N20), just how much gets into the cylinder. The 6.0 will make more power because it flows more to begin with. Mostly because of the head design. The oval ports made after 1975 are garbage. The vortecs are a far sight better than the peanut ports but still garbage. It's also a ridiculously low compression ration of about 8.1:1 some have been reported as low as high 7's. Where the Lq9 is around 10:1 and the Lq4 is 9.1:1 not to mention the Combustion Chamber is way more efficient giving you a much better burn. The 6.0 with cam and intake will put 400 to the wheels. The 454 makes probably 215 RWHP from the factory :( . Now do a head swap and some serious tuning and the playing field just got leveled. Short of that the LS wins, not b/c the procharger is better than the whipple, because the LS flows more. I say all this with a broken heart as I have a 90 TBI 454 and a whipple, but with heads/cam/intake/Tuning Ability coming this spring I should level the playing field a little.

Sorry for the novel.

[rebelbowtie]

While were on the topic of boost and compression ratios, why is it that usually large displacement boosted engines run lower compression? My little 2.0 has 10.5:1 compression and still runs 12-15psi of boost on a tiny stock turbo under 3,000rpm. My limited knowledge of forced induction is usually a larger charge of air being forced into an engine it's usually hotter and that's why you run intercoolers and water/meth injection to keep intake temps low.

So on paper it'd make more sense to run high compression and low boost than low compression and high boost?

[1998454]

I don't know...why are some blown alcohol engines 6.5-1? I think with lower static compression more air can be pushed into the cylinder before detonation happens. Your turbo car probably has a well designed combustion chamber and it probably has alot of cooling around the chamber.
While were on the topic of boost and compression ratios, why is it that usually large displacement boosted engines run lower compression? My little 2.0 has 10.5:1 compression and still runs 12-15psi of boost on a tiny stock turbo under 3,000rpm. My limited knowledge of forced induction is usually a larger charge of air being forced into an engine it's usually hotter and that's why you run intercoolers and water/meth injection to keep intake temps low.

So on paper it'd make more sense to run high compression and low boost than low compression and high boost?

[rebelbowtie]

I don't know...why are some blown alcohol engines 6.5-1? I think with lower static compression more air can be pushed into the cylinder before detonation happens. Your turbo car probably has a well designed combustion chamber and it probably has alot of cooling around the chamber.

These are the kind of things I want to learn now that I own a turbo car.

[V3NOM GTO]

The compression on a 454 vortec is 9.0-1. you are listing low compressions found on the tbi truck. But from a forced induction point i would rather have 8-1.

I did not know that. 9.0:1 is still a good boost compression ratio for anything that's not going to be crazy high amounts of boost "depending on the head design/motor itself"


While were on the topic of boost and compression ratios, why is it that usually large displacement boosted engines run lower compression? My little 2.0 has 10.5:1 compression and still runs 12-15psi of boost on a tiny stock turbo under 3,000rpm. My limited knowledge of forced induction is usually a larger charge of air being forced into an engine it's usually hotter and that's why you run intercoolers and water/meth injection to keep intake temps low.

So on paper it'd make more sense to run high compression and low boost than low compression and high boost?

It's all about Knock (precombustion). It comes from Compressing the air (boost) which causes heat. Boyle's Law. Alot of it is Combustion Chamber design and head material (Iron Vs. aluminum ). The better CC design and Aluminum material help to bleed off heat, keeping the cylinder temps down, allowing to run more boost. There is a give and take, higher compression will make more power but it comes at a price, less boost before knock. You can cheat a little with Meth Injection or Alcohol to cool temps but you are limited. If you go too far in the other direction (7.5:1-8.5:1 ) you start running into a motor that is a DOG at low/ no boost. It's give and take like everything else.


I don't know...why are some blown alcohol engines 6.5-1? I think with lower static compression more air can be pushed into the cylinder before detonation happens. Your turbo car probably has a well designed combustion chamber and it probably has alot of cooling around the chamber.

Right here!

[2500ak]

Your method of reading the forum doesn't exempt you from respecting the sub-forum designations.

So, by that reasoning what? We have to treat it like a foregone conclusion? Nonsense.

I don't even have a horse in this race. My truck has an old iron block Gen III LQ4, the opposition the OP is talking about is a Gen 4 LY6. Both are 6.0L engines, but they're different enough that I don't much care who wins, although I am entitled to an opinion.

[ZF6LLY]

i wanna see pics of both! and definitely pics of both towing!!!

[1998454]

He is entitled to his uneducated opinion....and as soon as he figures out what a 454 is, he will express his true feelings. LOL.
What's a forgone conclusion? That people shouldn't come into a section of the forum arguing against whatever that sub-forum is dedicated to..... ABSOLUTELY! If you're going to enter into some kind of reasonable discussion, at least know what the opposition is all about, rather than assuming! Maybe next you should go on over to the street section and tell them lifted trucks are better, or vice versa.

[Outlawz2004]

What's a forgone conclusion? That people shouldn't come into a section of the forum arguing against whatever that sub-forum is dedicated to..... ABSOLUTELY! If you're going to enter into some kind of reasonable discussion, at least know what the opposition is all about, rather than assuming! Maybe next you should go on over to the street section and tell them lifted trucks are better, or vice versa. The thread is asking about what people of this forum think would do better boosted. Its not like its a private subforum. If you only want opinions from people that have big blocks then you know its going to be a one sided conversation. Its an open forum, open to everyones opinion. I have been around both engines, my brother has a 1998 reg cab 454. The truck has low end power in a very limited rpm range, sucks gas like no tomorrow, and feels like forever between gears(manual trans). The 6.0 makes it power throughout the power band and will respond to boost better, so thats why I gave my opinions. Both trucks have their places, both will makes tons of towing power.

[2500ak]

The OP has a big block, not an 6.0 LS engine. He's asking other big block owners what they think, not the LS engine is the end all be all crowd. Had he wanted to hear from anyone and everyone, he could have posted in the general performance area.

What he actually asked was how well it would hold up against a friends truck, a relatively stock NNBS with a procharger.



I have a buddy who just bought a Procharger setup for his 07 RCLB 2500HD.


So, what you're saying is that he only wanted answers from people who deal exclusively with big-blocks? From the specificity of the question that is not what I gathered, but alright.

In my earlier posts I stated that unloaded the LS would be faster. Loaded the 454 would most likely have the advantage. With the LS getting the best mileage overall. The 454 would likely be more fun to drive, as it is going to be fitted with a manual transmission.

I fail to see how any of this speculation is offensive.

I've never gotten such hateful responses to posts on this forum, and I've posted here for a while.

[Outlawz2004]

The OP has a big block, not an 6.0 LS engine. He's asking other big block owners what they think, not the LS engine is the end all be all crowd. Had he wanted to hear from anyone and everyone, he could have posted in the general performance area.
I believe that you have totally misread what the thread is about. I dont believe anyone said the LS engine is the "end all be all". You want a private opinion from someone, use the private messages or email, post in the open forum and its open for discussion.

[1998454]

No racing, just the truck that pulls the best with 8k behind it, 454...no brainer.
I have a buddy who just bought a Procharger setup for his 07 RCLB 2500HD. How do you guys think my Whippled 454 will fair against it in normal truck duties? I am not talking hitting the drag strip and running the 1/4. I am talking about hooking 8000 LBS behind the trucks a seeing who out pulls who. I plan on trying to get him to give me a run to see what happens.

[N0DIH]

Just don't forget 1 psi boost makes more hp than 1 compression point. And running 1 compression point less will let you easily run more than 1 psi boost more. So build for it. I agree, my 301 Turbo was 1 7.5:1 engine, yes, below boost rpm, it ran fair, ok, would hold its own with a 302 Mustang GT (85-88 timeframe), but when boost came in, no contest.... It was just tailights for him.

Personally I would much rather drop some compression, and add a smaller pulley and run much more boost. But many things have to be taken into account like if it is a Eaton or other Roots blower that heats the air so badly, then the high boost levels might be a curse too. Many many factors need to be evaluated to do it right. And it often isn't cheap.... :)




I did not know that. 9.0:1 is still a good boost compression ratio for anything that's not going to be crazy high amounts of boost "depending on the head design/motor itself"



It's all about Knock (precombustion). It comes from Compressing the air (boost) which causes heat. Boyle's Law. Alot of it is Combustion Chamber design and head material (Iron Vs. aluminum ). The better CC design and Aluminum material help to bleed off heat, keeping the cylinder temps down, allowing to run more boost. There is a give and take, higher compression will make more power but it comes at a price, less boost before knock. You can cheat a little with Meth Injection or Alcohol to cool temps but you are limited. If you go too far in the other direction (7.5:1-8.5:1 ) you start running into a motor that is a DOG at low/ no boost. It's give and take like everything else.



Right here!

[durbo.jones]

Wow, I didn't intend for this to become an argument.

To answer the question on the fuel system. I am running FAST 36lb injectors and a Walbro 255 pump.

I do want to throw out there that I am a huge fan of LS motors and have built and tuned a few of them. I also, like the GMT-400 body style more than the NBS or the NNBS body styles. Which is why I am building my truck rather than leaving it alone and buying something different. I have never messed with the LS motors with Boost which is why I posted the original question. When my friend and I actually run I will definitely get a video of it and post it up for everyone.

[Outlawz2004]

Wow, I didn't intend for this to become an argument.

To answer the question on the fuel system. I am running FAST 36lb injectors and a Walbro 255 pump.

I do want to throw out there that I am a huge fan of LS motors and have built and tuned a few of them. I also, like the GMT-400 body style more than the NBS or the NNBS body styles. Which is why I am building my truck rather than leaving it alone and buying something different. I have never messed with the LS motors with Boost which is why I posted the original question. When my friend and I actually run I will definitely get a video of it and post it up for everyone.
Cool deal. I actually am a huge fan of both. I like the looks of both, I like the simplicity of the LS engines and NBS trucks, but like the way the OBS feels like a better built truck. I like the OBS interiors better, I like the way the old engines make their torque down in the rpm band, but on the same note I love revving the crap out of my LS engine and seeing it scream.

[V3NOM GTO]

Just don't forget 1 psi boost makes more hp than 1 compression point. And running 1 compression point less will let you easily run more than 1 psi boost more. So build for it. I agree, my 301 Turbo was 1 7.5:1 engine, yes, below boost rpm, it ran fair, ok, would hold its own with a 302 Mustang GT (85-88 timeframe), but when boost came in, no contest.... It was just tailights for him.

Personally I would much rather drop some compression, and add a smaller pulley and run much more boost. But many things have to be taken into account like if it is a Eaton or other Roots blower that heats the air so badly, then the high boost levels might be a curse too. Many many factors need to be evaluated to do it right. And it often isn't cheap.... :)

I absolutely feel ya on the lower compression for boost concept. And your right on the money there is a point of deminishing returns. I think for the most part unless your building something for a truck or a really nasty street car (500 RWHP +) then stock compression will give you all the boost you want. The eaton or whipple style twin screw style superchargers start to just make more heat and no more boost at a certain rpm so you just need a bigger blower. I agree with you 100% on the not cheap part, but like I said before, the type of trucks most of the guys on this forum are talking about will not need much to do what they want them to do. There are some guys over on Performancetrucks.net that are a whole new ball game, but most of them run LS series stuff. Wonder why that is :colby04: . But for the most part the tired old BBC's can do pretty good.

[Miles B]

I don't think many people read that this thread was about towing a decent sized load.
Yes we know your LS motors are awesome at making horsepower.
Yes I would have an LS motor in any street rod/truck I build from now on.
No I would never have anything but a big block in my towing truck. It's the only thing I would ever use a big block for.

When they build a 450+ cubic inch big block LS, then I will put that in my truck.

[V3NOM GTO]

Ask and you shall recieve. Let me know how the swap goes :D

http://www.jegs.com/i/GM%20Performance/809/19244611/10002/-1?CT=999

[Miles B]

That aint a big block.

[V3NOM GTO]

Well aren't you picky :). It's big enough, it will get the job done. Everybody says the LS motors can't tow? I think most of them are just designed for the higher RPMs but that can be fixed with a cam and intake swap.

[Miles B]

I'm just not into stretched small blocks. I didn't say LS motors can't tow, I just prefer a big block. It's what they're designed for. Plus I like messing with the big motor, and I can't see any other logical place to house it. Big block muscle cars aren't my deal.

[N0DIH]

I would like to see a 427 LS7 with L92 heads and cam in it and see how it tows....

[V3NOM GTO]

I'm just not into stretched small blocks. I didn't say LS motors can't tow, I just prefer a big block. It's what they're designed for. Plus I like messing with the big motor, and I can't see any other logical place to house it. Big block muscle cars aren't my deal.

Ok, I can follow that. I've owned both BBC and LS and the BBC is still really stock so maybe I have a biased opinion, might change when I get done with my build this spring.


I would like to see a 427 LS7 with L92 heads and cam in it and see how it tows....

You and me both. Drop one off at my house and I'll tell you how it does :)

[PonyKiller87]

The 8.1 L18 is as close as you will get to a LS style big block. It has BBC dimensions with LS style heads and fuel system on it.

[1998454]

LOL, that's impressive. But for 10 grand I could put a 572 in my truck.
Ask and you shall recieve. Let me know how the swap goes :D

http://www.jegs.com/i/GM%20Performance/809/19244611/10002/-1?CT=999

[Miles B]

My impression of the LS's differences to the SBC are the 6 bolt mains, improved block design (strength), the head design and the fuel and spark systems. IMHO, basically better heads and electronics, and the strength in the bottom end to carry it.

I'm adding the fuel and spark systems from the LS to my 454. It already has a darn strong block and mains. And I'm adding Brodix RR-O heads which should be on a par with the LS heads in terms of development. The only thing I'm unclear on is the valve angles and what performance difference they represent.

Apart from that I don't see too much of the "magic" in the LS series that I'm missing out on.

[Miles B]

LOL, that's impressive. But for 10 grand I could put a 572 in my truck.

Hahaha exactly.

[V3NOM GTO]

My impression of the LS's differences to the SBC are the 6 bolt mains, improved block design (strength), the head design and the fuel and spark systems. IMHO, basically better heads and electronics, and the strength in the bottom end to carry it.

I'm adding the fuel and spark systems from the LS to my 454. It already has a darn strong block and mains. And I'm adding Brodix RR-O heads which should be on a par with the LS heads in terms of development. The only thing I'm unclear on is the valve angles and what performance difference they represent.

Apart from that I don't see too much of the "magic" in the LS series that I'm missing out on.

Head and valve angle all have to do with how fast and how complete of a burn you get in the cylinder. It's WAY above my head, I just go along with what works.

[94_c/1500]

My vote for a better towing truck is the 454. And the fact it uses a twin screw compared to the 6.0L's centrifugal blower, my vote is for the 454. And if gets the trans swap, it'll be even better.

[silverado_lover]

The 8.1 L18 is as close as you will get to a LS style big block. It has BBC dimensions with LS style heads and fuel system on it.

:lol: The 8.1 IS a big block, just because it's an LS engine doesn't mean it can't be a BBC

[2500ak]

LOL, that's impressive. But for 10 grand I could put a 572 in my truck.

For ten grand why not up the ante and and get a GMC Thunder12?

http://www.thunderv12.com/


http://www.youtube.com/watch?v=HL0AT3k30DA&feature=player_embedded

stock rebuilds make 630 ft/lbs off idle (30 more than most of the 572 packages make peak), strong enough for some pretty serious amounts of boost or nitrous right out of the box, and the ability to make even the more well versed enthusiast say "What the hell is that?"

Not to mention an extra 130 cid.

[N0DIH]

Ahh heck, give me a LS7 with L92 heads and cam in it. That will pull like crazy...

I wish GM would bring back the 427 for trucks (just a LS7 based 427....)

[Miles B]

I'd like to see a new big block. LS style 6 bolt mains, alloy block, distributorless, oil pump, with a valley plate. Big block size, deck, journals..

[454cid]

:lol: The 8.1 IS a big block, just because it's an LS engine doesn't mean it can't be a BBC

The 8.1L is not an LS engine. It's a Gen VII big block. The heads/intake and ignition use the same/similar technology as the LS engines. LS is not a type of engine, it's a series of GM small blocks. If it's not part of the particular series of small blocks, it's not an LS engine.

[2500ak]

Ahh heck, give me a LS7 with L92 heads and cam in it. That will pull like crazy...

I wish GM would bring back the 427 for trucks (just a LS7 based 427....)

That's what they're doing. GM claims their next block will be a DI 7.0L engine.

Back in 2007 they made a DI 6.2L to test the concept. Made a little south of 500hp, with the entire low end getting what they considered a 10% increase over the port injection version. The low output version of the port injection 6.2L is rated for 403HP and 392 ft-lbs. If they're 10% figure is accurate torque would have been about 431 ft-lbs. That's assuming they're using the low output version.

Which would be impressive assuming it's true, especially out of a 6.2L engine. Now add to that an extra 4/5th of a liter, and you're looking at something that might give a lot of good diesels cause for concern.


From what I've read they're not going to make DI L92 heads because, although they're probably the best flowing stock OHV heads in a long time the DI hardware crowds the combustion chamber.

If that's so I imagine that's why they're redesigning, and giving the engine a larger bore. More space above the piston to work with like all the old short stroke bigblocks (Type-W, FE, etc...) used to have.

[Miles B]

Wouldn't surprise me. The European and Japanese 4.0 - 5.0 V8s are making 100hp per litre with DI. I wonder what the aftermarket will be like for DI in a few years.

[N0DIH]

Even my 4.0L DOHC V8 in my DD makes 75 hp/L and it is a 1998..... GM is WAAAAY behind the times... The Cad Northstar is barely making any hp/L more than a LS1.....

The LS1 makes 61 hp/L
The L37 Northstar makes 65 hp/L
The Cadillac CTS-V LSA engine makes 90 hp/L (supercharged)
The Corvette LS7 makes 72 hp/L
The Lexus GS350 makes 87 hp/L (DI engine)

I have a spreadsheet I have been working on for something else but I have a column for hp/L and torque/L

[N0DIH]

I just hope GM doesn't do what they normally do. When they make strides in flow and efficiency, they cut the camshaft way back and kill the power off. But if they were to leave the came specs higher, they would hit a home run big time. But alas, they always seem to strike out with a man on 2nd....

[2500ak]

I just hope GM doesn't do what they normally do. When they make strides in flow and efficiency, they cut the camshaft way back and kill the power off. But if they were to leave the came specs higher, they would hit a home run big time. But alas, they always seem to strike out with a man on 2nd....

My intuition is that they have to because of industry emissions standards.

I think they've been playing it smart though. They've made huge advancements in getting the engine to breath easy, they've already got (or claim to have) proof of this in that concept L92.

Now they'll add DI, crank up the displacement, and a DI friendly CR (somewhere between 11.5:1 - 12.5:1), and it'll have the ability to deal with the extra demands that get placed on the heads and cam to get that cylinder cleared out for the next powerstroke. Otherwise I wouldn't expect the engine to compete incredibly well against Fords Ecoboost and whatever Dodge comes up with.

Adding DI to the Gen III head design would yield marginal benefits in most configurations. If they went to that technology when all the Euro cars started to they wouldn't have been able to market it like it's a big deal. Although really it is.

On the other hand GM has disappointed before. They never made the V10 455 version of the LQ4, they discontinued the 8.1L gas engine, and the D-Max never made it into any American 1/2 ton trucks.

[Miles B]

To be fair though, the smaller Japanese/Euro motors are making their hp numbers by turning high RPM. The bottom end is nothing to write home about. I'd always rather sacrifice some rpm to have a bigger motor turning a ton of torque out down low and lose the bragging rights of that "at 7000 rpm" high hp number. Their motors are also generally overhead cam four valve. I also like to sacrifice a little power for a motor that I don't mind working on. I hate pulling quad cam V8s apart. I do hope that GM retains the pushrods but gets to 85hp/L. While the CTSV makes 10hp/L less than its European competition, it does push out over 100 extra hp. And if they sold it here, I would buy it over the RS4/M3 every day of the week.

[N0DIH]

Funny you mention DMax, they are one of the highest, if not the highest from GM in the actual torque to the ground numbers. 765 lb/ft torque, 3.10 first gear, 3.73 rear gear and a 245 75 16 can put down around 8800 lb/ft at 1600 rpm. That is over 2x more than the L29 454 does at 1600 rpm. And still even if we could launch at 3250 rpm (torque peak), that is only 4168 lb/ft. And that is a L29 with 4.10's.

Makes one wonder why GM doesn't simply drop the L92 in a 2500/3500 as is. More HP than L29 and L18, nearly as much torque as L29 and not far off from L18. Seems a shoe in. But they didn't they came up the LY6 (replaced the LQ4), which has:

Horsepower: 367 @ 5200 rpm Torque: 375 lb.-ft. @ 4000 rpm

http://www.gminsidenews.com/index.php?page=Engine_Guide

The LRZ 8100 makes 325 hp 3600 and 450 lb/ft @ 2800 rpm. It is still listed, but it is in 4500-up only trucks.

I think DI will help a lot. the 3.6L DI makes over 300 hp and it is a V6. That is great hp. Diesels haven enjoyed DI for years and years, and it is just now coming to gas engines because they have to to keep up with emissions and power needs. DI and Variable Cam timing both would do wonders for the GM lineup. VVT is showing up here and there, but it should be on every engine.


My intuition is that they have to because of industry emissions standards.

I think they've been playing it smart though. They've made huge advancements in getting the engine to breath easy, they've already got (or claim to have) proof of this in that concept L92.

Now they'll add DI, crank up the displacement, and a DI friendly CR (somewhere between 11.5:1 - 12.5:1), and it'll have the ability to deal with the extra demands that get placed on the heads and cam to get that cylinder cleared out for the next powerstroke. Otherwise I wouldn't expect the engine to compete incredibly well against Fords Ecoboost and whatever Dodge comes up with.

Adding DI to the Gen III head design would yield marginal benefits in most configurations. If they went to that technology when all the Euro cars started to they wouldn't have been able to market it like it's a big deal. Although really it is.

On the other hand GM has disappointed before. They never made the V10 455 version of the LQ4, they discontinued the 8.1L gas engine, and the D-Max never made it into any American 1/2 ton trucks.

[2500ak]

I still haven't driven anything with gas direct injection, but one of the things that intrigues me, from a design standpoint is a kind of low end tenacity I've observed in diesels, and whether or not that will carry over to the gas application.

On a gas engine when the rpms fall below a certain level engines tend to become extremely anemic, regardless of a lot of other factors. You only really see this when you're driving a stickshift, but it's a problem that's been getting progressively better as fuel systems have advanced.

My project truck, for example, is carbureted, and when you start in to high of a gear, or dump the clutch too fast in 2nd the engine lugs a few times and dies. It's a big block with a lot of low end torque, but there is that rpm threshold where the engine just looses power.

TBI trucks with stickshifts area a little more tolerant of this, port injection engines like a few Jeep I6 motors with the Renix injection system I've driven even more so.

A friend of mine has a project truck I helped him restore that has an old IDI 7.3L IH Navistar engine in it. You dump the clutch in any gear (except overdrive) and the whole truck jerks violently, but it doesn't stall and eventually brings the truck up to speed.

My intuition is that below a certain rpm the velocity of the air going into the cylinders isn't enough to keep the afr from being lean or rich, but in the DI application because the fuel is metered and put directly into the cylinder that isn't an issue. Well, at least not until throttle is applied.

If we expand this to apply to the entire low end of an engine that would otherwise only really excel past, say 3000 rpms like the LS engines tend to, then that really would explain the 10% increase GM claims to have observed.

Same thing with long, small intake runners, or putting the injectors higher up on intake to increase the velocity of the fuel at lower rpms, which usually helps bolster low end power. Putting the injector in the cylinder should add any benefit you might get from a design like that, without having to deal with the extra resistance and loss of air flow it would result in.

This is just speculation of course.

[454cid]

I still haven't driven anything with gas direct injection, but one of the things that intrigues me, from a design standpoint is a kind of low end tenacity I've observed in diesels, and whether or not that will carry over to the gas application.

Diesels typically start and finish making power with lower RPMs than gas engines.

[N0DIH]

I have my 454 right now setup to engage TCC really low, so I can cruise around 35 mph at 1000 rpm TCC locked. It feels like a stick, not the smoothest all the time, but trying for better city mpg. I wouldn't do this for anyone unless they knew what they were in for.... :)

But it is nice to feel the TCC lock and the truck just lugs like a stick, but still has great power to move the Burb along nicely.

[Miles B]

I'd say it's got something to do with their compression ratio and the slow burn of the diesel fuel.

[454cid]

I've driven a Traverse with a DI engine, and a 6 speed auto. I didn't care for it in one respect. Upon letting off the gas to slow down (no braking involved) I often had to apply more gas pedal than I wanted to, to get back up to speed. It would downshift, and wouldn't provide the smooth increase in speed back up to where I had been. I'm guessing that's more a function of the final drive ratio, and the double (?) overdrive of the transmission.