GM's new 4.2L DOHC twin turbo V-8 !!

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mk e
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by mk e » Mon Dec 10, 2018 8:24 pm

Truckedup wrote:
Mon Dec 10, 2018 8:12 pm
Real excitement is on two wheels... :D
Indeed.....and light throttle needed to prevent understeer due to an overloaded front tire :)
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Newold1 » Mon Dec 10, 2018 11:04 pm

Here we go again! My fault for bringing up the new mid engine Corvette!
Let's get this conversation back about engines and engine technology.
Isn't it great that a major auto manufacturer can still see fit to develop and produce a great new high tech performance engine platform and maybe even have it as an affordable crate engine offering for the performance market in the near future. Congratulations GM , don't stop now!
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by exhaustgases » Mon Dec 10, 2018 11:53 pm

Instead of these cumbersome DOHC nightmares, I'd like to see the Achates engine take off, if done right it would be more maintenance free than the OHC engines everyone has gone to. And much better power density as well.
You do have to love it when they put the timing chain / drive at the flywheel end, which does make sense, except when something goes wrong. The job, requiring engine removal or transmission removal, like with the W8.

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by mk e » Tue Dec 11, 2018 7:23 am

Newold1 wrote:
Mon Dec 10, 2018 11:04 pm
Here we go again! My fault for bringing up the new mid engine Corvette!
Let's get this conversation back about engines and engine technology.
Isn't it great that a major auto manufacturer can still see fit to develop and produce a great new high tech performance engine platform and maybe even have it as an affordable crate engine offering for the performance market in the near future. Congratulations GM , don't stop now!
The thing is there really isn't much info to discuss. General specs is it......its currently a "black box" and everything beyond the basic spec is conjecture. It might be a great engine, is might be a turd, it will certainly be more expensive to work on than sb of ls setups.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by n2xlr8n » Tue Dec 11, 2018 10:14 am

Very nice technique from rider 43 :D
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Truckedup » Tue Dec 11, 2018 11:49 am

n2xlr8n wrote:
Tue Dec 11, 2018 10:14 am
Very nice technique from rider 43 :D
They appear to be vintage class bikes.....200 HP at 12,000 plus rpm N/A from 1000 cc with stock exhaust and emission controls is state of the art in bikes...The emission standards for bikes is less strict than cars and it's easier to get high output from less CC's..but still...
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by mk e » Tue Dec 11, 2018 12:12 pm

Truckedup wrote:
Tue Dec 11, 2018 11:49 am
n2xlr8n wrote:
Tue Dec 11, 2018 10:14 am
Very nice technique from rider 43 :D
They appear to be vintage class bikes.....
It's a vintage race..... 1995 or maybe 96, battle of the twins. 43 is an 860cc H-D that made about 110hp at 9000, 1 off frame (although I sold a couple near copies later).
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Newold1 » Tue Dec 11, 2018 12:58 pm

Please start another thread on Vintage bike racing and their riding techniques, Please! :roll:
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by mk e » Tue Dec 11, 2018 1:58 pm

Just filling time until you have more details on the new dohc 4.2 ;)
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Bazman » Tue Dec 11, 2018 4:00 pm

This was the OHC engine I was hoping for from GM....

Image

The Mercury Racing SB4 7.0, basically an LS7 with quad cams and 32 valves. Rated at 750 horsepower at 7,500 rpm on pump fuel (closer to 775). Maximum recommended engine speed is 8,000 rpm.

https://www.enginelabs.com/news/sema-20 ... te-engine/

Now THAT motor with an OEM warranty would be tits :mrgreen:

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Newold1 » Tue Dec 11, 2018 5:26 pm

This is Mercury Marines DOHC LS7 base engine conversion. Cool looking power plant BUT:

Been available for about 4 years now. Has not been accepted well in the marine trades or aftermarket performance markets.

Way to expensive! Can't remember exactly but I think they are priced at about $75,000. Won't come close to meeting current emissions standards. Does not have great horsepower per cubic inch production versus just some stock GM LSX and LSA engines

Mercury was trying to work off some of the racing success of their big QV$4 1350-1650HP offshore racing engines which use the same DOHC cylinder head technology . They sell for about $225,000 a pop!

I think it's pretty much an abject failure for Mercury Marine and it will probably disappear shortly if it has already not.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by hoffman900 » Tue Dec 11, 2018 5:48 pm

I never understood that price point, especially considering a NASCAR lease engine is probably around $50k.

Economies of scale I guess.
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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by GARY C » Tue Dec 11, 2018 5:54 pm

grandsport51 wrote:
Fri Nov 30, 2018 8:04 am
I'm a little skeptical of OEM's reliability testing before introduction of new technology
When I was a Ford Service Manager we introduced the 2.0 Koln built OHC engine and
Stated that the engine had millions of miles of durability testing in Europe
Well of course the rocker arm otc cam lobes started failing promptly some before 20,000 miles.
Proper Types of oil not specified
The Reynolds metal Vega Bores similarly failing likely because of susceptibility to coolant leaks
And having a tiny cooling capacity.Corrected with "Durabilt" engine blocks
NorthStar and other aluminum block engines head bolt thread failures repaired with Threadsert s
Now the new multiple lawsuits and recalls in re CP-4 Bosch pump failures in diesels because of incompatibility
With US Grade diesel fuel.
Mercedes AMG head bolt and gasket failures.
And hundreds of more examples
So it's just my opinion but I wouldn't own the new engine without a full coverage extended warrantee !!
Dave B.
Historically in the auto industry the first year or two of a new model release is basically consumer funded R&D.
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by GARY C » Tue Dec 11, 2018 5:57 pm

Newold1 wrote:
Fri Nov 30, 2018 9:42 am
I think sometimes WEon this engine forum should spend a little more time studying and educating ourselves in new engine development offerings and understand in particular in a case such as this before we start making so many OPINIONS not necessarily based on real facts and information.

Some more real information on this new GM RPO LTA twin turbo engine:

1. Development on this engine began over 4 years ago at GM.
2. The engine has undergone over two years of actual on road in testing durability cells at GM.
3.This engine is currently being set up for assembly as we speak at the new GM high performance engine assembly facility at Bowling Green Kentucky
4. 20 psi boost on this new engine design is mild, it can easily sustain 30-40psi of boost for extended horsepower and torque.
5. Having 5500 psi fuel pressure in engine fuel lines is not a problem at GM look at fuel pressure levels in LT5 and Duramax diesels.

Just saying I think a few on here should take a more complementary view point with new engine technology, especially when it comes from a company like GM with incredible engine platform success it has had in the last 20 years or so!

I agree with Hoffan900 here:
WE SHOULD DO MORE HAILING AND LESS BAILING!
JMHO :wink:
Wasn't it you that just said these company's are all about propaganda and money?
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THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBER AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!

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Re: GM's new 4.2L DOHC twin turbo V-8 !!

Post by Bazman » Tue Dec 11, 2018 7:27 pm

Newold1 wrote:
Tue Dec 11, 2018 5:26 pm
This is Mercury Marines DOHC LS7 base engine conversion. Cool looking power plant BUT:

Been available for about 4 years now. Has not been accepted well in the marine trades or aftermarket performance markets.

Way to expensive! Can't remember exactly but I think they are priced at about $75,000. Won't come close to meeting current emissions standards. Does not have great horsepower per cubic inch production versus just some stock GM LSX and LSA engines

Mercury was trying to work off some of the racing success of their big QV$4 1350-1650HP offshore racing engines which use the same DOHC cylinder head technology . They sell for about $225,000 a pop!

I think it's pretty much an abject failure for Mercury Marine and it will probably disappear shortly if it has already not.
At $75k I'd agree with you... however they only sell for $33k turn key with a tuned ECU and accessories! They were under $30k for the engine alone. They've sold quite a few, and it'd be an real shame if it were not a profitable success!

Yes, you could likely build an NA LS7 OHV that made 750hp for under $30k (including buying the LS7) BUT it won't be anything like this, and it won't come with a manufacturer's 1 year warranty, and frankly, there'd be very few engine builders that could build an engine as good as this for under 30k that would run to 8000rpm and be used daily. No doubt there's a handful in here that could sell and make a profit at $30k something that would compete - but I bet it needs more maintenance being OHV at 8000rpm. My 2 cents, and glad to be proven wrong :P

A blueprinted/massaged one of these would easily make 800hp. I think they're very cool and reasonably priced for the exotic piece they are. I'd buy one myself if I had a spare 30k laying under the mattress :lol:

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