What is a "workhorse p30" ?

darin338 wrote:
Purchasing a 2000 Newmar Dutch Star. Owner says it has a GMC 7.4 which I believe is a 454?

However, the carfax states it is a "workhorse" p30, which I always thought the workhorse was Chevy 8.1, not GMC 454?

Also, I've searched and searched and searched and have yet to find another 2000 Dutch Star with a 7.4 GMC in it. They either all have the V-10 or are diesel.

The 8.1 (just a little more stroke than the 7.4 for the most part) were in later P30 chassis (a generic term and actually refers to a P32 in Motorhomes) that was bought from Chevy GMC in 1999. Most are found on the later Workhorse W chassis, however. At any rate, you're very close to a transition year for those engines. The 7.4 is yes, 454 cu in., but not called that with the use of the metric system to describe the later non-carb fuel injected engines.

There is no such thing as a P30 chassis no matter who it was made by.

How is that for confusing? What is often referred to as a P30 chassis, means the first number in the designation is a 3. As far as drivetrains go, the Vortec version of the 454 was a pretty good engine. It is a GEN VI block, which means roller lifters, and much better oil delivery. It was a major step in the durability improvements in the BBC. Vortec heads should be classified as fast burn, so you should get decent mileage. The 8.1 for the most part is just a bigger engine, and some minor refinements of the design. The 4L80e was based on the TH400 and many of the internal parts are interchangeable. It is a fairly durable trans, but it is not an Allison. It can be built to be very tough, without a lot of effort. Your biggest issue is putting 35 feet on any P series chassis is going to be overloaded. Maybe not on paper, but in real practicality, it is just too long and heavy. Tag axle versions were little better. Shorter versions of the that chassis worked very well.

darin338 wrote:
Thanks! But now I'm ever more confused. He told me the Engine is a GMC. The carfax states, "workhorse p30" Maybe they dropped in a used engine, who knows?

Chevy and GMC shared the same engines and transmissions, GMC never designed their own engines. They both used the 7.4L/454CI and the 8.1L/496CI in their pickup trucks, Suburbans, Tahoes, etc. The 8.1L is basically a stroked 7.4L. Both are good solid engines with 8.1 providing more horsepower and torque. The 7.4 was first introduced in 1970, I have one in my 1970 Chevelle SS, have one in the MH too. They produced millions of them over the years. I would prefer an 8.1 and Allison trans but the 7.4 and 4L80E trans is a good combo.

rgatijnet1 wrote:
None of the P chassis coaches had the 8.1L engine with the Allison transmission. For that combo you have to go to a coach with the heavier W series chassis. The 8,1L engine was used on the later P series chassis but it was coupled with the GM transmission, which is a fine transmission but it is not the Allison.
As with any coach, check the unloaded weight and the maximum gross weight and see if that coach will allow you to load the coach the way you would travel. The P series chassis are usually rated several thousand pounds lighter than the W chassis.

This.

I've got a P32 chassis on my 2005 Fleetwood. This was the last year that Workhorse offered the P series. It has the 8.1L and the 4L85E GM transmission. It's a decent drivetrain and more than sufficient for the job.

Handling is OK, but not the greatest. It rides and handles like a delivery truck, which I believe is what this chassis was originally designed for. Handling can be improved by careful weighing of the coach. Be careful not load the rear to heavy as it lightens the front end and can cause it to wander.

I owned the 89 Pace Arrow on a P30 chassis. 454 and chev tran. Tran pan shaped like the state of Texas. I installed steer safe and the handling was Ok. My main complaint was the Moryde rubber rear springs in rear. It sagged badly. Had the Moryde rubber springs replaced on warranty 3 times under warranty with less than 8,000 miles.

Agree, 35' is pushing the capabilities of the P chassis. If a wide-track, that is an improvement. Yes, the W chassis would be a better choice for that size coach.

Wheelbase/overall length is also a handling issue-- what is is?

And, yes, starting in 2001 the P chassis came with the 8.1. We have several friends with just that chassis/drivetrain on their Safari Treks.

darin338 wrote:

wolfe10 wrote:
I would agree, the 8.1/Allison was better, but the 7.4/GM transmission was a solid performer.

What about the P30 chassis? Its holding a 35 ft newmar coach. Heard there might be handling issues?

In my opinion the P series chassis are not the best handling.
Workhorse improved the handling by introducing a wider trck version after 2001, I believe, not sure of the year. The P series utilized an air assisted front suspension with air bags in coils springs, which allowed for adjustment of ride and handling.

None of the P chassis coaches had the 8.1L engine with the Allison transmission. For that combo you have to go to a coach with the heavier W series chassis. The 8,1L engine was used on the later P series chassis but it was coupled with the GM transmission, which is a fine transmission but it is not the Allison.
As with any coach, check the unloaded weight and the maximum gross weight and see if that coach will allow you to load the coach the way you would travel. The P series chassis are usually rated several thousand pounds lighter than the W chassis.

wolfe10 wrote:
I would agree, the 8.1/Allison was better, but the 7.4/GM transmission was a solid performer.

What about the P30 chassis? Its holding a 35 ft newmar coach. Heard there might be handling issues?

I would agree, the 8.1/Allison was better, but the 7.4/GM transmission was a solid performer.