: 4BT into a 93 Chevy...



rwthomas1
03-15-2008, 10:42 AM
Hello All,
I have a 93 Chevy C2500HD with the 6.5TD and NV4500 5speed and 3.42 gears, 2WD. The engine has actually been excellent for me. For 252,000 miles it has been completely reliable and pretty cheap to own. Recently it developed a knock that I believe is two lifters that are very dead. I will be tearing into it shortly to determine the true problem. It is possible this is the beginning of the end for the 6.5. If this proves to be the case I am considering swapping in a 4BT. Some will say why not the 6BT? Too long, too many mods to get it installed.

My initial searching here shows that my truck may be the ideal swap candidate. The NV4500 with a new clutch/flywheel from South Bend bolted to the 4BT with the adaptor set from a P30 van. The truck already has hydroboost brakes. The 3.42's should prove ideal for highway cruising. I rarely go faster than 70-72mph. The existing radiator should work fine. Would have to do a custom intercooler and fabricate engine mounts, throttle linkage, etc. Overall, it seems quite do-able.

The simple solution to the potential problem is to purchase a used 6.5 engine. They are available and not too expensive. I have no issue with the 6.5, unlike others here, it has given me great service and good mpg's, so if you are planning on posting what a turd it is save your breath.

That said, the 4BT is interesting to me just because. The truck is used every day as a construction/contracting vehicle. I tow a 3000lb tool trailer and less frequently a 7000lb trash trailer. I think the 6.5 was rated at 210hp/370tq stock and new so a 4BT tuned to about 400ft/lbs should give similar performance. My reading here indicates tuning to this level is fairly easy and pretty reliable.

It would seem finding a 4BT equipped P30 would be the way to go. Complete engine, correct PS pump, bellhousing, throttle bits, etc. Would still have to fab or find AC comp mounts.

So is it a good idea or not? Thanks, RT

jdemaris
03-15-2008, 11:20 AM
Hello All,
I have a 93 Chevy C2500HD with the 6.5TD and NV4500 5speed and 3.42 gears, 2WD.

I have no issue with the 6.5, unlike others here, it has given me great service and good mpg's, so if you are planning on posting what a turd it is save your breath.


I think the 6.5 was rated at 210hp/370tq stock and new so a 4BT tuned to about 400ft/lbs should give similar performance. My reading here indicates tuning to this level is fairly easy and pretty reliable.

I've thinking of doing the same. I have several 6.2 and 6.5 diesel trucks. These GM engines are usually whipped by 250K, but there are few that make it to 500K (I've got one). My main concern is fuel mileage pulling a moderate load.

A few comments though. The 1993 6.5 block was one of the strongest ever made by GM, and many later versions were not as strong. Also, you mention power. Correct me if I'm wrong, but I don't believe there was a 370 lb. torque 6.5 available for your truck in 1993. There was a higher-toqure option for 1 ton trucks only - and the 3/4 and 1/2 turbo 6.5s were rated 190 horse at 3400 RPM and 240 lbs. of torque at 2000 RPM. Compare that to a
4BTA with 120 horse at 2500 RPM and 302 lbs. of torque at 1500 - and it seems the Cummins, if anything, is a better puller.

That being said, I don't own one and have yet to find out for myself. I do have a 92 W250 with a 5.9 Cummins - and it greatly outperforms my Ford 7.3 turbo - in pullling power and fuel mileage. And, the 6BT is so much more than my 6.5T, I don't even try to compare.

I like the 6.2s and early 6.5s, but they are tinker-toys compared to the Cummins if you lay their internal parts, side by side.

sdstriper
03-15-2008, 12:08 PM
I tow a 7x16 enclosed frequently with a 6cyl. Dodge Cummins 3/4 ton, licensed for 7 tons and rarely exceed that weight. My opinion is I doubt you would be happy towing regularly with the 4cyl Cummins basing my opinion on my 6cyl. Cummins towing experience. I must also point out I have zero experience with the 4cyl. Cummins other than mucho research etc. for a future project. I do have everyday hands on with the 6cyl. Cummins though and it is capable although there are limitations due to my particular set-up. I would either repair the 6.2/6.5 or swap to the 5.9 Cummins for an everyday towing unit.

57 napco
03-15-2008, 10:54 PM
The 92-93 6.2LHD was rated at 165hp @3400 and 285lbft @ 2000.
The same vintage 6.5TD was 190hp @3400 and 385lbs @ 1700.

JakeDiesel
03-16-2008, 06:47 AM
I would go with the cummins 3.9. It has less hp than the 6.5, but has more torque then the 6.5. Alot of time the engines that replaces the 6.5 in the bread vans was the 3.9. The 3.9 can easly make as much hp as the 6.5. If you want to keep your mpg and mayhe get better I would go with the 3.9. Another thing the dry weight of a 6.5 is 780 pounds, the dry weight of a 3.9 782 pounds, the dry weight of the 5.9, is a 1000 to 1100 pounds. The 3.9weighs 2 more pounds then the 6.5, another reasonI would go that route. With the 5.9 you would have more power, and not as good of fuel mileage. 5.9 and 3.9 are the same engine with 2 cyl cut off the back.

jdemaris
03-16-2008, 10:56 AM
The 92-93 6.2LHD was rated at 165hp @3400 and 285lbft @ 2000.
The same vintage 6.5TD was 190hp @3400 and 385lbs @ 1700.

In regard to those 6.2 specs, I don't believe it. There isn't much new "under the sun" with any of the 6.2s. C-codes, and J-codes with minor differences in valve sizes, intake manifolds, precombustion chamber sizes, injector nozzles, and fuel rates. All else is pretty much the same, regardless if C-code, J-code, civilian or military. I've got over 40 of them. I've driven and worked on them since they came out, and also swapped many. For the most part, you stick a LD C-code into a 3/4 ton rig with 3.73 or 4.10 gearing, and you can hardly tell the difference from a J-code setup the same way.

Where do your specs come from? I don't believe there is a NA 6.2 on the planet capable of what you posted - and I've got over 40 of them.

I've got spec charts direct from GM and the U.S. Army for every year made or used and don't find what you are posting.

The highest rated 6.2 I've ever come across is the rating GMC used in 1993 for the HD J-code 6.2. 145 horse at 3600 RPM and 260 lb. ft. of torque at 1900 RPM. Same year, highest rated 6.5 turbo is listed as F-code L65 available only with GVRW over 8500 lbs. - 190 horse at 3400 RPM and max torque at 380 lb. ft. at 1700 RPM.

Same year - again 1993 - with Chevy instead of GMC ratings - highest power 6.2 in 3/4 or heavier trucks only is rated 148 horse at 3600 RPM and 248 lbs. of torque at 2000 RPM. 6.5 turbo under Chevy specs got listed lower than GMC - why - I don't know. VIN code F is rated at 190 horse at 3600 RPM and much lower torque.

The 6.5 turbo sold for 1/2 ton trucks, 1992 and 1993 - for GMC and Chevy is rated at 240 lbs. of torque at 2000 RPM. Jumps to 360 - 380 lb. ft. when installed in a heavier GVW truck. Type, or a corporate lie - I don't know. I haven't owned nor have I driven many 6.5 turbos -the bulk of my GM experience has been with the Toroflows, Olds 350s, and DD 6.2s. By the time the 6.5s got thin-wall casings and electronic controls on injection (with many problems) - I moved on to Ford IH and Dodge-Cummins stuff for heavy work.

rwthomas1
03-16-2008, 09:30 PM
Thanks for the input thus far. I have the highest rated 6.5TD mechanical injected engine made. Truck gvw 8600. Its the HD 2500 with 8lug hubs, full-floating axle and nv4500. The truck weighs 6100lbs empty, thats with me in it at the dump scales.

I have no complaints with the 6.5. It pulls as well as I need it to and I "leaned" on it a bit to improve GM's efforts. Heath mechanical boost controller for 11psi, BD 3" downtube/4"exhaust, mandrel bent 2.5" crossover, cold air kit, turned up pump, blueprinted injectors, gauges, GM8 turbo, etc. It runs pretty well for a 6.5 with 250K on the clock. That said, it may be approaching its service life. Thats why I'm here.....

Going to a 3.9liter seems like a big step down in cubic inches but these engines move box vans around loaded with goods. Seems if tuned to where my mildly warmed 6.5 is it would do the job. Just have to decide if I want to go through a project if the 6.5 has major issues or just swap a newer 6.5 in. Decisions, decisions.

RT

blakerj10
03-17-2008, 08:57 AM
I had a 94 6.5 td in a chevy blazer. I loved it. They do get dogged a lot when compared to the pulling power of the similar vintage cummins or powerstroke, but it was not ever intended to be a heavy puller. They are much cheaper to maintain and operate. I also had a 98 1 ton at work with a flat bed and a similar truck in a ford. The ford did better with loads on the interstate, but in town, the 6.5 would boost so quick that it was just easier to drive.

I think I would just stick a new or rebuilt 6.5 back into that pickup. Seems a lot easier and cheaper.

57 napco
03-18-2008, 12:36 AM
I have had several late 6.2L trucks. :) All state the hp on the air cleaner housing. My current shop truck is a 90 K2500. Hp as printed on the air cleaner is 165hp @ 3600 with 51.0mm/3 of fuel. I think the later 6.2's rate their horse power at slightly lower RPM. I work on diesel pickups for a living, do allot of 6.2's. I do think that the horse power listed on the air cleaner is gross and not net. As the '92, 93's 6.5's. are rated at 200 HP on the air cleaner.


As far as replacing a 6.5 and 5 speed, with a 4BT I am not sure it will do so well. The wide gear spreads of the NV4500 are not condusive to a small displacment turbo'd motor. I think if a truck had a 4L80E, it would do allot better. The small displacment really hurts at low RPMS before boost kicks in. Especially with such a wide ratio transmission. My '96 truck shattered the 4L80E that was in it and having a fresh rebuilt NV4500 sitting on the floor, I have debated weather or not to install it. I did allot of heavy towing with it and really wonder if it would do well with a 5 speed. The torque converter can be a big adbvantage, keeping RPM's and boost up. If you didn't tow heavy with the truck I would say a 5 speed would be fine. Or if it had a close ratio tranny.

B1jetmech
03-18-2008, 08:44 PM
I would definitely go with the 4BT into your truck over the 6.5TD.

I owned a 92' 3/4 ton HD chevy truck with a 4L80E...and it had 250K plus! It was an excellent runner, however I sold it.

I installed a 4BT in my 93' Suburban 4x4 with 3.42 gears and it runs just fine. I'm sure my burb might be the same weight or heavier then your truck but the 4BT moved the "fat" burb' around just fine.

There are many pluses going with a cummins over a 6.5TD...such as cold weather start up. There are no glowplugs in the cummins and my motor fires right up in very cold weather. The durability that I won't bore you with because we all know how good they are. They are easy to work on. Parts are plentiful...just look on Ebay for cummins verses 6.5 parts selection. There are alot of cummins being used in so many applications.

If you retain your NV4500 tranny you will have all the pulling power you need especially with the 6.34 1st gear which is a good stump puller.

All in all, go with the cummins 4BT. If you find a 4 speed version out of a bread van, there will be very little mods needed to drop it in your truck. I don't know if the clutch from your NV4500 will bolt up because I haven't installed a manual, just an automatic. But someone on this forum will know...Good luck!