4BT vs 6.5

[Sickcall]

My neighbor just finished putting a 6.5 dsl into his fj40 Landcruiser and it looks very very nice. A very good fit under the hood. He went the 6.5/nv4500direction because of availability, increaed horesepower, and lower noise.

I have been waiting for the next DoveBid auction but the 4BT's on the westcoast are getting scarce for some reason. I thought about going the 6.5 route but checked the trucks with the 6.5's and almost everyone has a head gasket problem. Is this indicative of another problem with the engine or just the head gasket? I assume only the leakers are being surplused off and this is a problem with the application of this engine in a big truck?

I guess I can wait until a better auction comes up for the cummins.

[Charles Talbert]

I'd wait

The Cummins is a far better choice & a much better quality engine than a 6.5. I know lots of folks disagree & I have no problem with that, to each his own. Having dealt with diesels in various applications for many years, a few things have stuck with me. Good engines are built by a few other companies as well, Cat, International, etc. Just look around, I don't believe you'll find any other superior quality engines that have proven themselves better than a Cummins for the cost invested & the cost of general upkeep. I've dealt with them all, Cummins made a believer out of me years ago. Don't get me wrong, all the major brand quality has suffered because of trying to stay competitive, sad but true.

[JimmieD]

I think the west coast shortage is temporary. The availability of stepvans for auction is somewhat cyclic dependent on end of fiscal year figures. Months back a load of vans were sold through dovebid.com and then not much more. I'm thinking that at the beginning of next year you'll see a repeat as inventories are again appraised and juggled so many vans will be available.

At this time Frito Lay has a policy that ALL surplus disposal of stepvans etc. will be through dovebid.com and with the current inventory racking up miles everyday there have to be some retirees coming each year. Many of these Cummins were refits in the beginning of the 90's so it's time to change them out.

[MoparNorm]

Jim,
I don't have the numbers on Bread vans running vs. vans auctioned, but I believe that part of the motive behind the huge amount of auctioned vans this year was both age and primarily the new federal requirements for ULSD in fleet vehicles. Seems to me that there are tax incentives to help speed up the changeover.
I'm sure Charles has more insight on this as he may have heard more from his Cummins Rep.???
MN

[JimmieD]

I agree that this is no doubt part of the picture but I believe it is a relatively minor aspect. There is one primary reason these vehicles are being retired: $$$$$$. The large percentage of these units have the GM/Pontiac Turbo/Hydro 400 trans. Great tranny and mighty stout, but we're in a different ballgame here. The transmission can handle the Cummins torque to a certain extent, but only to that point. That point is 17,000 lbs!

The GVW is not all that high on these vans, 7,500-9,000 maybe. TH400 can handle that easily. Problems are the loaded vans can run 15,000-17,000 lbs and the TH400 can't handle that in stop and go, crash 'em/smash 'em devil-may-care route driver use with Cummins TORQUE pushing the load back and forth.

None of the trucks I've seen even have a tranny cooler! Are you kidding me, guys? What, pray tell, were you thinking...? TH400 deep aluminum trans pan used on these route vans is a very nice piece but it's just not enough to keep the tranny temps under control, and TH400's are weak in reverse anyway if ya ask me.... so this leaves a problem for Frito Lay or whomever.

Do a full rebuild with valve body, shift kit, HD clutches, drums, bands, bearings, seals and the whole works to at least full race specs, retrofit a tranny cooler, install tranny cooler electric fan for rush hour gridlock, trans temp sender and thermostatic switch to control cooler fan, tranny temp gauge, educate driver to hit the manual over-ride switch if temps rise, keep vehicle downtime to a minimum or provide alternate vehicle for a week or so during trans refit and make all of this cost effective on the equipment depreciation go-round? OR: Sell it cheap, cut the losses, take the tax credit, and buy a brand new zero maintenance van with a full mfgr. service warranty and cost it against operating expenses again at tax time...

I believe that's why these vans will continue to be available until these versions are all sold and after that? Should be more on the west coast in May/June this coming year.... start saving up now, boys!

[JimmieD]

By the way, I think the TH400 or the 700R4 [or whatever they're called] would be just fine behind a Cummins in a lighter vehicle like an M37 or Power Wagon even if you wanted to run it really hard. That of course assumes a tranny cooler is installed, because guys around here have brains...!

[MoparNorm]

Jim,

I don't want to get blamed for bashing the turboslush400, but even gm gave up on it and now uses Allisons behind their diesels. In fact the Allison 1,000 series is at it's limit in the newer Dura Max (Izusu**) trucks. It's max rating was 550 ft. lbs and the diesel wars pushed by Cummins* is making torque in the 650 range now. The new Cummins 6.7 is using an Aisin transmission that is said to be bullet proof...time will tell....= )
MN
*Navistar has a marginally higher torque rating than Cummins, but at 1,000 rpm higher, which really isn't useable in a truck motor.
**gm finally admitted that it's inhouse diesels belong in the outhouse.

[JimmieD]

Well, I should have at least been more specific: should be fine behind a 4BT in a lighter vehicle. I base that on their known performance in a very heavy truck used in less than ideal conditions without a tranny cooler. I however opted for NV4500... :~ )

[Sickcall]

Jimmie, I didn't know bread or chips could weight so much!!!

I had considered (in my mind) the 6.5 because of the 190 HP figure. I was thinking that to be a better ratio figure for the M37, but I don't want the head gasket problem either.

Since I already have a freshly rebuilt 3053A tranny waiting,I think I will take Charles advice and wait. That, and the amount of "been there, done that" assistance available.

[JimmieD]

Good idea! Haven't heard Charles Talbert give any bad advice yet and I've been listening for a few years so far....

[Sickcall]

What horsepower numbers do you think you can get from the 4bt without any major modifications, things like fuel pump or turbo mods?

[JimmieD]

What horsepower numbers do you think you can get from the 4bt without any major modifications, things like fuel pump or turbo mods?

This depends on intended use for one thing. I'm planning on a lot of towing so that sets certain limits on EGT's that might not present a problem on a daily driver. With GP useage you can just back off the go pedal and EGT's drop immediately. Towing on a long hard pull and having to keep the load in motion makes it a lot harder to back off.

Regardless, from what I've found out so far it's pretty easy to get around 160-175hp with little more than tweaks to the Bosch VE pump and minor turbo upgrades. The 4BT usually has a 3" exhaust, equivalent to a 4" performance exhaust on a 6BT. 4BT uses a Holset H1C turbo with a 16cm exhaust housing, same as found on 1st Gen 6BT's. That same turbo can feed a 6BT to at least 280-290hp and 700+ torque. A set of bigger injectors with the pump tweaks really warms things up on hp and EGT's. Taking those hp/torque numbers and dividing by 6, multiplying by 4 gives 186hp/466 torque. Not bad for 3.9L displacement.

Making the horsepower through added fuel may require some work to bring EGT's down. This can come from more turbo, turbo upgrades and/or water/methanol injection. I'm going with turbo upgrades and water/meth because I believe the H1C is plenty of turbo for this engine. Using the right mods [HTT Stage II and possibly a 14cm exhaust housing] I can get power where I want it and still have excellent towing abilities.

JimmieD