new engines for the GMCs

[mike sadlon]

Some of you may be following this from the Facebook page. I have been looking into the viability of the LS engines for GMC motorhomes. Problem number
one was getting the LS engine to hook to our 425 transmissions. The Panrail on the LS interferes with our differential. I solved the connection
problem by rotating the transmission up about 25°. That allows clearance around the Panrail and diff. The next problem was the transmission now
interferes with the step area. It could be worked around but it illuminates a True Bolt-in situation. I have identified an aftermarket block that
would get us 427 in.³ relatively easily. And still fit in the stock location. The target for the horsepower of this engine would be 450 HP and 500
pounds of torque. They can have late-model fuel injection and coil on plug spark system. I'm ready for questions

 

[justin brady1]

So what are you going to do about the step? move it back a foot and lose the floor space?

Call me what you will, but that level of modification is not going to appeal to anyone but someone with a completely gutted project coach.

--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455

 

[Jim Hupy]

Wonder how a tm 425 will like 500 foot pounds of torque? Probably not much,
I expect.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

> Some of you may be following this from the Facebook page. I have been
> looking into the viability of the LS engines for GMC motorhomes. Problem
> number
> one was getting the LS engine to hook to our 425 transmissions. The
> Panrail on the LS interferes with our differential. I solved the connection
> problem by rotating the transmission up about 25°. That allows clearance
> around the Panrail and diff. The next problem was the transmission now
> interferes with the step area. It could be worked around but it
> illuminates a True Bolt-in situation. I have identified an aftermarket
> block that
> would get us 427 in.³ relatively easily. And still fit in the stock
> location. The target for the horsepower of this engine would be 450 HP and
> 500
> pounds of torque. They can have late-model fuel injection and coil on plug
> spark system. I'm ready for questions
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[mike sadlon]

It does not need to go back it needs to go up about 2 inches to clear the rear of the transmission

 

[justin brady1]

Gotcha, thats not terrible, you could simply build a small cowl to cover it.
--
Justin Brady
http://www.thegmcrv.com/
1976 Palm Beach 455

 

[mike sadlon]

The new engine does not need any modifications To the coach. The motor will need a new front mount , custom oil pan new exhaust.

 

[mike sadlon]

From all of my research the stock numbers were 330 to 350 HP. And 450 to 500 torque. The new engine would have a little more horsepower because of
the ability to Rev up a little freer. We could make more horsepower and torque but this is the goal of the combination

 

[jim kanomata1]

Apparently, your not aware that the Big block Chev engines have been
adapted to the 425 trans by many.
It works well once it is done correctly.
The 425 trans, when slighty modigied and proper parts used like the ones
Manny T does for me. My Cad 540 with Twin turbo,Intercooled,port injected
has been holding up with over 80,000 miles.
You need to know that I have been around mods on these since 1980 and have
rubbed shoulders and exchanged info with them.

> From all of my research the stock numbers were 330 to 350 HP. And 450 to
> 500 torque. The new engine would have a little more horsepower because of
> the ability to Rev up a little freer. We could make more horsepower and
> torque but this is the goal of the combination
>
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> GMCnet mailing list
> Unsubscribe or Change List Options:
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>

--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502

 

[john r. lebetski]

The 70 Eldorado E car had similar HP and Tq so that is not an issue. I just don't think a low nickel BB Chevy (if that's what you are suggesting) will
have the longevity of the Olds, but that will he offset by availability.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[hal stclair]

Great motors and can be built to make more power than could ever be used in our rigs. Modifying the oil pan is no trivial matter though as they are a
structural element of the block. The poor ol' 425 is kind of out of place though with about half the gears you'd like. It can be built robustly enough
to take the guff though so thats an easy problem to contend with. I am quite curious how your final drive and half shafts would fit-probably need
custom length shafts at the least IF the angles can be made to work. The raised step is a non issue IMO and a really simple thing to deal with. You
would have to deal with the electronics as well which isn't too bad, either custom made or home built depending on your abilities.
Would probably be a fun project but not for the faint of heart. $$$ is the big thing on a project like this as well as 'stick-with-it-ness' to see it
through to the end.
Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1974 Eagle Bus 45',w/slideout

 

[mike sadlon]

I know the big blocks have been installed. But I don't believe there's any combination of intake that will let it fit underneath the stock engine
cover. If I remember correctly even Daves 8.1 has a raised hatch

 

[hal stclair]

> The 70 Eldorado E car had similar HP and Tq so that is not an issue. I just don't think a low nickel BB Chevy (if that's what you are suggesting)
> will have the longevity of the Olds, but that will he offset by availability.

These are modern motors either all aluminum or iron block versions, that are typically good for 200,000 miles or more. Great platform in most
applications, Corvettes, trucks, rear drive cars etc. Same bore spacing as the old small block Chevy but nothing else carried over. All had aluminum
heads, composite intakes. 4.8l,5.3l,5.7l,6.0l,6.2l,7.0l sizes stock with lots of aftermarket support. All aluminum versions were in the 440lb range
which is a real plus.
Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1974 Eagle Bus 45',w/slideout

 

[mike sadlon]

Just so everyone understands. There are two things going on here. First is the LS conversion. The diff stays in at stock location then there is an
adapter to rotate the transmission 25°. Then there is another adapter to rotate the engine back 25° so what is level. The goal was a kit to be able
to put a junkyard 6.0 LS engine into one of our coaches. New transmission pan new oil pan new front mount And a transmission mount. The goal for the
kit price point was under $2000. The rotated engine with a low profile intake should fit under the Hatch. But the rotated transmission will not fit
underneath the step.

 

[mike sadlon]

The other is a brand-new engine block available from world products small block lower LS cylinder heads. It's a hybrid they created. I have prices
for a completed short block. Working on the pricing to build a complete engine.

 

[mike sadlon]

The small block lower only needs a oil pan and front mount to make it work everything else stays in the stock location. These blocks have already
built to handle over 800 HP. Considering the quality of the parts that you have to use on this aftermarket combination, our 450 horse will last a
very very long time

 

[mike sadlon]

Over the last week as I've starting the pricing on this, I was hoping to be able to build assembled motor ready to go with exhaust for under 10 grand.
My first quote on the short block balanced and assembled is over $5000. And it's looking like it would need to be closer to $12,000 to be done with
computer ready to Run.

 

[LQQKatJon]

I really dont know a thing. Other then being around 6.0 ls conversions in grand wagoneers. Prefect for those, but I just dont get how that
junkyard engine can pull around our coaches. Works perfect for the wagineers, but we are twice the weight. Must be some more performace upgrades
you had in mind other then taking a stock tahoe engine and putting it onto the 425? And at what price?
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[mike sadlon]

The 6.0s and 6.2 have been the go to motor in the 1 tons since the demise of the 8.1. And their GVW's are way above ours. The 6.0s what outwork the
Ford V10's in our service Fleet.

 

[RonaldPottol]

Has anyone looked into a lock up torque converter? It ought to help freeway
milage. They make them for the TH-400

Great to hear of some cheaper motor options, I'd love Manny's diesel, but
I'd love to keep the extra $20-30k in my pocket.

> The 6.0s and 6.2 have been the go to motor in the 1 tons since the demise
> of the 8.1. And their GVW's are way above ours. The 6.0s what outwork the
> Ford V10's in our service Fleet.
>
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[hal stclair]

Like I mentioned, great motors but they need rpm for the towing you're talking about. To get to our weight levels you would probably need a 4.1 gear.
At that rpm your economy wouldn't be much different than the present combination. You might be up with Manny's kit for money expended.
Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1974 Eagle Bus 45',w/slideout