L300 4D56 "comfortable" RPM

[Feds]

As I plan for my big engine swap, I want to get a sense of how flexible the 4D56T is. What would you say is a "comfortable" engine speed?

The reason I ask is that I read a lot of complaints about the Delicas running out of gear at highway speeds. Looking at the specs, they have a pretty short rear end, and the OD's aren't super tall either. Assuming 29" tall tires, 100 kph is right around 3000 rpm, and 120 occurs at 3600.

Using the stock gearing in the MPV and B2600, 100 kph would come up at 2200 rpm, and 120 would be about 2700. Does the engine operate happily in that range, our would I be lugging on the lower end?

The other option I am considering is the taller OD out of an RX-7 transmission. That would put 100 kph at 2000 rpm, and 120 at 2400. This seems like it would be too tall to me, but what do you guys think? Does a delica pull o.k. at 2000 rpm? What engine speed requires a downshift?

[jessef]

Automatic or 5spd ?

What are you putting it in and mating it to ?

What's the gear ratio in the diff's ?

[FalcoColumbarius]

The typical layout for the 4D56T in the L300 is a follows (assuming they're tuned):

Automatic transmission:

• 80 KPH ~ 2,000RPM
• 90KPH ~ 2,250-or so RPM
• 100KPH ~ 2,600RPM*

Manual Transmission:

• 100KPH ~ 3,000RPM*

I can't tell you much about the Manual Transmission as my Chamonix is Automatic but I understand that you can trade gears out, depending how handy you are with a wrench. Also, there are shop manuals for the transmissions in L300 Delica Downloads (see "Board Index").

What I can tell you is my automatic transmission L300 is quite comfortable cruising at 120KPH (around three grand), however ~ it costs more to run at that speed as I go through fuel much faster. My ideal cruising speed on the "open" highway is 105KPH. My best recorded mileage at that speed is 11.5 kilometres per litre or eight and a half litres per 100 kliks. Also I have discovered that she uses less fuel at 105 kliks than at 80 kliks. I believe this is because the injector pump squirts less fuel once the RPM has settled at a certain speed, not sure, but those were my findings whilst travelling daily from North Vancouver to Aldergrove, one week doing it a 80 kliks (2,000RPM), next week doing it a 100-105 kliks (2,600RPM). Go figure.

Falco.

*These speed ratios can vary depending on wind conditions, &c..
Tyres: LT235/75R15 Yokohama Geolandar AT/S @ 41PSI

[nxski]

Automatic transmission:
80 KPH ~ 2,000RPM
90KPH ~ 2,250-or so RPM
100KPH ~ 2,600RPM*

It also depends on what additions your vehicle has. Mine used to conform to these general guidelines however with the addition of a basket, roof rack and thule box it is now operating at;
80 KPH - 2,000RPM
95 KPH - 2,500RPM
100 KPH - 2,750RPM

Not a huge difference but it is noticeable. On average my RPM's drop by 500 at highway speeds when the vehicle is stock. I also managed to drop an average of 250 RPM at highway speed by removing and blocking my egr. It should also be mentioned that this is a cl roof vehicle so a bit bulkier than Falco's low roof model.

Did I understand correctly that you wanted to put a rotary engine in a Delica or am I getting this backwards. It seems to me that you want something that will provide a good amount of torque if you want to use the vehicle for off-roading or even just to get the "2 ton brick" off the line.

[thedjjack]

2,000 rpm is to slow for 80km+ motor likes to spin more then that.

I am a 5 speed on 31" tires... I would think if you could get your cruising speed at around 2,800 RPM I suspect good mileage. However< I would think cruising over 110 km/h might be pushing the motor at that RPM.

I do not have an EGT hooked up so not 100% sure how hard it is working. In the MPV should have room for a big intercooler.

[Feds]

Thanks for the replies everyone. The whole plan is this:

4D56T into Mazda MPV. The early B2600 used a 4G54, so the transmission will bolt up to the 4D56. I am going to use a Mazda 5-speed, and the early MPV (manual) transfer case, as it has 2wd, AWD, locking centre diff, and low range.

I don't have the exacts in front of me, but the MPV came with 3.9x gearing, and the B2600 has a .81 OD. There is an RX-7 gear set that has a .71 OD as well.

My plan is to work the gearing to stick 110-115 kph right at the sweet spot for fuel economy in 5th (seemingly 26-2700 RPM). I may end up being pretty slow off the line, but the MPV is about 1000 lbs lighter than the Deli, so that should make up for it a little.

What I can tell you is my automatic transmission L300 is quite comfortable cruising at 120KPH (around three grand), however ~ it costs more to run at that speed as I go through fuel much faster. My ideal cruising speed on the "open" highway is 105KPH. My best recorded mileage at that speed is 11.5 kilometres per litre or eight and a half litres per 100 kliks. Also I have discovered that she uses less fuel at 105 kliks than at 80 kliks. I believe this is because the injector pump squirts less fuel once the RPM has settled at a certain speed, not sure, but those were my findings whilst travelling daily from North Vancouver to Aldergrove, one week doing it a 80 kliks (2,000RPM), next week doing it a 100-105 kliks (2,600RPM). Go figure.

That's exactly what I was looking for, thanks.

[FalcoColumbarius]

You're welcome. Bare in mind that my Chamonix typically weights close to 2,400Kg with me sitting in it. Not sure how much your MPV weighs.

Falco.