TD42 torque figures vs Kw@ wheels

[KiwiBacon]

Would have been handy to have an ACTUAL rpm setting instead of a derived one, really doenst help using derived figures.

If you have the tyre outside diameter and all gear ratios, then you have rpm more accurately than most rev counters will display it.
But you need to measure the tyres and know the gear ratios.

Do you guys have a tacho lead you can attach to an injector line or even an optical one off the crank pulley?

[UGOTNUFN]

Would have been handy to have an ACTUAL rpm setting instead of a derived one, really doenst help using derived figures.

If you have the tyre outside diameter and all gear ratios, then you have rpm more accurately than most rev counters will display it.
But you need to measure the tyres and know the gear ratios.

Do you guys have a tacho lead you can attach to an injector line or even an optical one off the crank pulley?

Ok ive dug up a dyno printout that we can peruse ,just trying to get it posted.

http://members.iinet.net.au/~matthius/test.pdf" onclick="window.open(this.href);return false;

[BIG12HT]

Hi, I would like to add to this discussion if I may.

The figures for the vehicle in question were recorded by myself. They are accurate and at the wheels. It should be mentioned that the dyno day wasn't about being a horsepower hero - we were tuning the engine/turbo for best response and wide power and to maximize drivability. I needed the data to go back and evaluate a few things and it had a scientific style approach. It was a really good and exciting day which saw some great power and some high boost. The whole setup was exceptional on the vehicle which happens to be my cousins race truck.

To make 151kw @ 2000rpm at the wheels, with an assumption that there is zero losses for inertia and friction of drivetrain and elsewhere, the torque at the engine would be 716nm +/-1mm. So, obviously the engine makes more than that. The boost on this run was around 30psi and there was very little smoke to be seen when at full load. It has been calculated that the AF ratio was around the 16-18:1 area though this was not measured using a wideband - something for the future?.

I used 140cc for my spreadsheet calcs because the pump wasnt set at it's limit. I have had a look at many BSFC maps (DI and IDI)to get an understanding of what an IDI engine running at an 16-18:1 AF ratio and 2000rpm and have built a formulae to approximate the BSFC curve vs rpm for both DI and IDI diesels. In this case ~ 247gms/kwh was determined based on the inputting of rpm and injection type into the formulae. There is an over riding assumption that all values of interest are based on full load. I have been working on a formulae that also best follows the power loss vs rpm also.There are fixed and several variable components and it appears to get very close to the right numbers.

Anyway, plugging in 140cc (/1000 strokes), 6cyl, 2000 rpm, 96mmx96mm bore/stroke, IDI and an excellent intercooler (it IS excellent), the spreadsheet said:

151.9 RWKW (very close to what was measured at this rpm)
173.6 Flywheel KW
828.8 Flywheel NM

The dyno method was simply hold the rpm, and keep loading it up until the accelarator pedal is on the floor and the rpm was maintained. 151kw at 2000rpm was the result and was held for a few seconds - dyno got really hot too. The other rpms mentioned elsehwere were also tried and the results referenced. It is hard on everything (dyno/car/stress of owner...) but the power determined is a true value.

The problem with the dyno mode where you plant it and let the dyno measure the accelaration from say 1000rpm to a max set rpm (at least on the Bosch dyno in question) is that the Dyno, (this is an assumption by me), is tuned to load up within a certain time period. The way these diesels make power, with big turbo and the aneroid delivering the additional fuel after boost is obtained, is that it has a relatively (to small turbo of low boost) slow build in boost and therefore torque/power. My assumption is that the dyno determines that all the power is being made (due to a time/rpm intergral - kiwibacon, care to comment?) and starts moving the rpm up before the peak has actually arrived. As a result you just dont get the true power reading with this type of power delivery. Holding the rpm fixed, you do avoid the intertia based power loss however and this should be noted as a reason why the "power loss" will be less than normally seen on an accelartion run, however there will still be other considerable frictional losses in drivetrain, tyres to dyno etc. The small high response turbos such as the GT2860RS with its tiny 60mm exducer comp wheels suffer this far less.

It would be interesting to see this truck (which is totally in bits) on a 1/4 mile run (after being put back together) but as was mentioned, it isnt built for that - it is a Pro-Comp winching style truck. The figures obtained should still be representative of what is under the hood though.

[KiwiBacon]

My assumption is that the dyno determines that all the power is being made (due to a time/rpm intergral - kiwibacon, care to comment?)

That is how I understand it.
Did you manage to get any BSFC figures for a stock TD42T? I back calculated ~250 g/kwh for a 1HD-T and ~300 g/kwh (both at max torque) for a 1HZ using injection volumes from a service manual. These show the stock 1HZ runs very rich (~16:1) for a diesel and in fact runs similar injection volumes to the stock 1HD-T.

But anyway, back to Nissans.

[BIG12HT]

KB, I assumed you used the factory manual for pump setups and worked back - I know we discussed similar things for the 12HT way back when. At that time the marine diesel also was around the 260gms/kwh mark IIRC. I was quitedissapointed at what appeared to be lousy economy....

Having said all that, even if you worked at zero dyno loss, the 2000rpm values obtained would make for 285/kwh. Some loss has to be accounted for. Intake temps were very low. The merc OM617 IDI engine has peak BSFC at 80% torque load of 245gms (100% torque ~ interpreted 252gms). It isnt intercooled which may improve by further ~ 6% efficiency (237?). The engineering paper I downloaded for the "H" series Hino 5-7L 6cyl engines had peak BSFC values of:

1969 to 1972 – 258gms/kwh (Indirect, NA)
1972 to 1974 – 245gms/kwh (Indirect, NA)
1974 to 1977 – 245gms/kwh (Indirect, NA)
1977 to 1982 - 222gms/kwh (Direct, NA)
1982 – 205gms/kwh (Direct, Turbo)
1983 – 215gms/kwh (Direct, NA)

As a result, I feel relatively comfortable that we at least in the ballpark. If the AF ratio is optimium and the BMEP is increased, generally the BSFC is improved - at least that is what appears to be true in what data I have come across.

It is hard to apply science when you cant measure everything... That is where logic (?) is attempted to be use to fill in the blanks....

While the examples *(yours/mine) above are not from Nissan, I don't think it is off topic on the basis that we are talking IDI engine tech to determine what is achievable/realistic in a TD42 (in the absence of any BSFC data from Nissan).

[BIG12HT]

My assumption is that the dyno determines that all the power is being made (due to a time/rpm intergral - kiwibacon, care to comment?)

That is how I understand it.
Did you manage to get any BSFC figures for a stock TD42T? I back calculated ~250 g/kwh for a 1HD-T and ~300 g/kwh (both at max torque) for a 1HZ using injection volumes from a service manual. These show the stock 1HZ runs very rich (~16:1) for a diesel and in fact runs similar injection volumes to the stock 1HD-T.

But anyway, back to Nissans.

And I just realised I didnt answer your question - no, didnt have a base value. We did however see ~ 93kw at wheels at 2000rpm with only 85cc of fuel as I recall.

[PGS 4WD]

Drive train loss in not static, the loss at 200 kph is greater than at 100 kph due to windage, this is why large agressive tyres cause more loss,and a greater loss at higher speeds. You need increasing amounts of power to go faster due to wind resistance, if it takes 20 kw to drive the wheels at 100 kph it might be 70 kw at 200 kph depending on the tyre and 200 kw at 300 kph.

Beware manufactures quoted figures to as some quote gross and some net. A 2003 Lexus 470 make approx 161 engine kW gross but only 139 or so net. A gross figure is acheived without any ancilliarys, water pumps, alternators, blts and so. Chryslet\r went so far in the 70's as to drive the oil pump externally on the tripple webber 265 hemi. Holden and Ford do this, the only GM engine as yet to be given a true figure to SAE J1349 is the LS7. Some manufactures don't even have the emissions based tune and full exhaust on when acheiving the figures.

Joel

Joel

[Dzltec]

Interesting reading. Want to forward work out what 250 cc of fuel will give in a td42t from 2000-4000rpm for me.

From previous runs of this car does the graph drop away or do things differently, or are you expecting more from it? Remember dyno's are measuring torque, power is a output from it. Maybe driveline losses are getting higher with the more load put onto the vehicle/dyno, especially the tyres. May be fit a set of road tyres and see what it does.


Andy

[UGOTNUFN]

Interesting reading. Want to forward work out what 250 cc of fuel will give in a td42t from 2000-4000rpm for me.

Remember dyno's are measuring torque, power is a output from it.


Andy

How much boost do you plan on running for the given 250cc,50 will be a minimum i would suspect from what we already know.

So if we are seeing 220RwKw when loaded then why aren't we seeing the NM on the power run.

It has to be because of the lack of load on the rollers.???

[sswaffie]

Hmm very interesting reading , How good would it be for a ve pump to
produce + 200mm3/1000 st @ say 2000 Pump rpm! What is your fuel setting
@ peak Hp , i understand you say 140cc/1000 st @ 1000 pump rpm but what
at rated speed? We are seeing a substansial amount more from our pumps
@ 1000 pump rpm! But maby not At say 2000 pump rpm?Who knows ,Great thread though

[BIG12HT]

Interesting reading. Want to forward work out what 250 cc of fuel will give in a td42t from 2000-4000rpm for me.

Remember dyno's are measuring torque, power is a output from it.


Andy

How much boost do you plan on running for the given 250cc,50 will be a minimum i would suspect from what we already know.

So if we are seeing 220RwKw when loaded then why aren't we seeing the NM on the power run.

It has to be because of the lack of load on the rollers.???

Reply:

For sure it is lack of load; it has to do with the dyno presets for the load/time integral as Kiwibacon thought to (who is a Mech Eng by the way). The settings are ideal for engines that deliver a closer to instaneous throttle position to torque relationship. The second or so to build the torque tricks it.

[BIG12HT]

Interesting reading. Want to forward work out what 250 cc of fuel will give in a td42t from 2000-4000rpm for me.

Remember dyno's are measuring torque, power is a output from it.


Andy

How much boost do you plan on running for the given 250cc,50 will be a minimum i would suspect from what we already know.

So if we are seeing 220RwKw when loaded then why aren't we seeing the NM on the power run.

It has to be because of the lack of load on the rollers.???

If I stick to a almost stoichiometric AF ratio, but rich by diesel standards of 16:1, assuming an excellent intercooler and two different turbo arrangements for the two rpm zones and each compounded (so 4 in total...) with no worse than 1:1.5 IMP/EMP ratio, very approximately:

Assuming: 60 deg C inlet temps, 250cc/1000 strokes, 2 valve head, stock cams

2000rpm 56.5psi/84% VE
Flywheel: 310KW/1480nm
Wheels: 271KW

4000rpm 69psi/71% VE
Flywheel: 551KW/1316nm
Wheels: 428KW

bear in mind, many of the assumptions in this spreadsheet only work well as an approximation within a "normal" power range. Some of the fixed losses may not be adequately allowed for and reality will likely be a much lower loss. Also, the BSFC of the engine is anyones guess, I would expect it to improve slightly based on what is seen on the Merc diesels in Finland, but we are talking alot of fuel for a small displacement engine.

Also, my confusingly worded turbo assumptions were really trying to say "one tubo wont do all this". A compound would be required for the boost needed and they operate only over a very narrow range anyway, so two different setups would be needed for each rpm number listed.

[BIG12HT]

Hmm very interesting reading , How good would it be for a ve pump to
produce + 200mm3/1000 st @ say 2000 Pump rpm! What is your fuel setting
@ peak Hp , i understand you say 140cc/1000 st @ 1000 pump rpm but what
at rated speed? We are seeing a substansial amount more from our pumps
@ 1000 pump rpm! But maby not At say 2000 pump rpm?Who knows ,Great thread though

At 140cc (flat-ish to ~ engine 4000rpm AFAIK) the pump wasnt maxed out. Bear in mind this was a first run on the dyno and the pump which does flow more (I had nothing to do with the pump, the expert on the pump is he who started the thread - UGOTNUFN), it was not maxed out as I recall. I think that I am right in saying that the pump was built specifically for a targeted rpm range and power, not as an all out maximum flow pump. As it was it certainly was perfection for what it was intended. If he wants to build a higher flow pump, I have no doubt he easily can; it just wasnt the plan in this instance. The engine previously did 151rwkw @ 3300rpm with peak fueling of 115cc/1000 strokes at ? rpm, so a sensible increase with different turbo and intercooler configuration was implemented. It was designed (not with FEA mind you...), not thrown together.

[UGOTNUFN]

Hmm very interesting reading , How good would it be for a ve pump to
produce + 200mm3/1000 st @ say 2000 Pump rpm! What is your fuel setting
@ peak Hp , i understand you say 140cc/1000 st @ 1000 pump rpm but what
at rated speed? We are seeing a substansial amount more from our pumps
@ 1000 pump rpm! But maby not At say 2000 pump rpm?Who knows ,Great thread though

At 140cc (flat-ish to ~ engine 4000rpm AFAIK) the pump wasnt maxed out. Bear in mind this was a first run on the dyno and the pump which does flow more (I had nothing to do with the pump, the expert on the pump is he who started the thread - UGOTNUFN), it was not maxed out as I recall. I think that I am right in saying that the pump was built specifically for a targeted rpm range and power, not as an all out maximum flow pump. As it was it certainly was perfection for what it was intended. If he wants to build a higher flow pump, I have no doubt he easily can; it just wasnt the plan in this instance. The engine previously did 151rwkw @ 3300rpm with peak fueling of 115cc/1000 strokes at ? rpm, so a sensible increase with different turbo and intercooler configuration was implemented. It was designed (not with FEA mind you...), not thrown together.

Very tru i was given a brief as to what was wanted to achieve as the owner was reasonably happy with the previous combo but it just ran out of breath way too early for intended purpose. The original setup was with a different turbo that a very clever man had built a controller to operate of which it did BUT we had concerns about its reliability (electronic) in the scheme of what the car was to be used for and we also ran out of time. So we scratched our heads and looked for another turbo solution in a short amount of time. Which we did and came up with a custom setup that would get us over the line in the time we had,make good power/look after EGT's and be reliable.

The pump is still as it was for the original setup and time permitting before the next event (im currently building the engine) we will dable with it some more, but judging by its past performance in the last event we are pretty close to a good solution of power and reliability.

[BIG12HT]

It might be worth noting that the engine rebuild is not a result of the engine blowing up - in case anyone was wondering....., It some time back suffered from injestion of what I would call a "significant" amount of very muddy water that left gravel "post" turbo - this was ALL on the first setup with much lower power rating. This means all the hard dyno work and the last race was done on a questionable engine and it faired extremely well all considering!. Going forward it was thought by the builder and the owner that a carefull inspection and rebuild would be worthwhile. As was mentioned before, this is being designed to be reliable in an extremely harsh racing environment, not a dyno or drag queen, so it must be well thought out and well executed and race again and again.

[sswaffie]

Just trying to get my head around these figures? Did it make 110mm3/1000st
@ given rwkw(1650Rpm) OR did the pump produce 110mm3/1000st @ 1000
pump RPM and made 151rwkw @3300Rpm (engine) Not knowing what pump
produces @ Rated HP ? We race a Td42t with 223rwkw @30psi of boost
myself and my navigator race this in the same event ( cooper rally ) high
speed event) we are lucky to see 450 degree exhaust temps ! We are
pumping 180mm3/1000 st @ pump rpm of 1000prm with some install,
These things can take a fair bit of punishment!

[BIG12HT]

Just trying to get my head around these figures? Did it make 110mm3/1000st
@ given rwkw(1650Rpm) OR did the pump produce 110mm3/1000st @ 1000
pump RPM and made 151rwkw @3300Rpm (engine) Not knowing what pump
produces @ Rated HP ? We race a Td42t with 223rwkw @30psi of boost
myself and my navigator race this in the same event ( cooper rally ) high
speed event) we are lucky to see 450 degree exhaust temps ! We are
pumping 180mm3/1000 st @ pump rpm of 1000prm with some install,
These things can take a fair bit of punishment!

They sure can take punishment; such is IDI where pistons dont get such a hard time and they love the revs due to better combustion (but more heat and gas transfer loss hence lower overall efficiency).

Your EGT sensor sounds like it is either post turbo or really short/not in far enough and getting quenched by the exhaust manifold. That is very low EGT for the low boost at 180cc (14:1 AF ratio, should be fairly smokey too). Mind you, at peak power rpm (guessing ~ 3300rpm?), it may be ~ 155cc/1000 pump strokes and closer to 15:1. 180cc at 2000 engine rpm should get you over 1000nm at engine and need ~ 37psi to keep it above 16:1. Is this all on stock rods? - that is some torque!!.

If I recall correctly, the previous pump did "about" 115cc at 2000rpm (1000rpm at pump) and dropped to around 100cc at 3300rpm (1650rpm at pump). Boost was ~ 20-25psi range and ran leaner than current engine - good all round power.

*In my opinion* (that is a disclaimer since it not based on direct experience) The hard thing it appears is to not have to overfuel the engine in the low rpms to get decent flow at say 3000-4000rpm range. The current pump achieves this and makes it a bit special. You can get around this with turbo sizing to not bring in boost to hard too early and aneroid pin profiling, but it is just better all around if you can keep the fueling flat or even rising a bit with rpm.

[sswaffie]

Pump definatly puts out what i have specified , egt probe is post turbo and
in approx 3". AFR is quiet lean when in boost , we run no compensator on
our race car, clears quiet quickly no good for street use though, i have done
quiet a few compensated pumps for street application , did one last week
180mm3/1000 st @ 1000rpm and compensator could take 70mm3/1000st
out of the range , And yes i could still get the thing to idle, you physically
cant load these things up like you can on a dyno or long enough ,hence cool
egt's allong with head work which also helps with egt's they simply make to
much torque! Have had car on dyno and done 4 or so runs still cool egt's
pretty hard to get traction though, good fun getting these old oilers to go ,
good too see you guy s arn't full of crap and figures and have actually done
some R&D. HP is wank factor and tractive effort is what people should aim for !

[KiwiBacon]

Pump definatly puts out what i have specified , egt probe is post turbo and
in approx 3". AFR is quiet lean when in boost , we run no compensator on
our race car, clears quiet quickly no good for street use though, i have done
quiet a few compensated pumps for street application , did one last week
180mm3/1000 st @ 1000rpm and compensator could take 70mm3/1000st
out of the range , And yes i could still get the thing to idle, you physically
cant load these things up like you can on a dyno or long enough ,hence cool
egt's allong with head work which also helps with egt's they simply make to
much torque! Have had car on dyno and done 4 or so runs still cool egt's
pretty hard to get traction though, good fun getting these old oilers to go ,
good too see you guy s arn't full of crap and figures and have actually done
some R&D. HP is wank factor and tractive effort is what people should aim for !

With 30psi boost you could be dropping well over 300 degrees across your turbine in steady state. Much more in transient operation.
Basically, post turbo temps are useless for your application, you need to shift that probe.

What is your AFR under boost?

[sswaffie]

At which rpm? Fuel varies accross rpm range , I have a race comming up soon ill put a temp probe in pre turbo and let you know what i see , also ill do the same with afr meter , bit hard to tell you rpm while in car tach dont work .

[BIG12HT]

Hi sswaffie, sorry if it came accross that I didnt think your pump put out what you said, didn't mean it that way. I was more interested in what fuel it could deliver in the higher rpms because 226rwkw, while huge, should be achievable on a TD42 with 180cc from 2500rpm and if fuel doesnt drop off, should go way up from there. By my calcs, and they are not gospel, 180cc @ 4000rpm (2000 pump rpm) should get you just over 300rwkw (calcs said 308), and possibly quite a bit more if the losses that I built in to convert shaft HP to Wheel HP are a bit over the top. I remember a pump my younger brother built based on a phaser pump for his TD42. It sure had torque - seemed to almost rip the gearbox out from the torque, but the excitement was all over by 2500rpm, even though it happily reved to 4000rpm and held the power at the expense obviously of torque.

Also, I base my AF ratio calcs on an unmodified head with stock cams (just too hard for me to work out otherwise, but I can hard type in a VE that I want to use rather than it determining it using the formulaes in there), so you may get close to 100% VE at 2000rpm (I used 84%) and probably 85+% at 4000rpm (I used 71%) with a good port job etc, so for sure less boost is required and 30psi, which obviously works for you is enough.

At ALL times when referring to fuel, I am using the standard cc/1000 pump plunger strokes

[sswaffie]

Yes your quiet correct in what you say and yes it dosn't deliver the 180mm At
pump speed of say 2000 Rpm tapers off considerly, still not bad for cam
plate lift we are running though with your calc's can you tell me what fuel we
are delivering with the given Hp ? ill go through my notes and have a look i
got a fair idea but i will make sure ,be interesting to see what you come up
with and how accurate they are ( which im not doubting for a second !)
Thanks

[BIG12HT]

Sure, just give me the rpm, the HP/KW @ wheels (and corrected @ flywheel if you have it for reference) and I'll be right back at you.

[sswaffie]

RPM very close to 3000rpm , 223 rwkw and got no idea what driveline loss i have

[BIG12HT]

223rwkw @ 3000rpm
269.7kw @ flywheel
858.4nm @ flywheel
16:1 AF Ratio (could be 17:1 due to headwork, which is clean)
157cc/1000 strokes
BSFC: 267.2gms/kwh
~ 44lb/min Air @ 33psi

Please note: as for use of significant figures for the power/torque, the accuracy does not warrant the use of 4….however that is what the spreadsheet spat at me. I would say it is accurate to +/-5%

[UGOTNUFN]

RPM very close to 3000rpm , 223 rwkw and got no idea what driveline loss i have

What gears and tyres are you using as i can give you a well documented idea of what i will be within %3-4Kw at 3000Rpm

[BIG12HT]

Maybe I should ammend that to +/- 2% accuracy ;-)

[sswaffie]

265 /70/17 4.375 and trans 1:1,
As for fuel figures i think your very close by memory (couldn't find data sheet on my pump specs) within probaly 5mm3/1000 st

[UGOTNUFN]

Maybe I should ammend that to +/- 2% accuracy ;-)

Tru that, if they are a medium treaded tyre and not full M/T treaded then at 3000Rpm under full load you would expect around 25Kw and ever increasing to as high as 35 as they bag out and heat up,which itself creates adhesion to the rollers increasing losses.

[KiwiBacon]

At which rpm? Fuel varies accross rpm range , I have a race comming up soon ill put a temp probe in pre turbo and let you know what i see , also ill do the same with afr meter , bit hard to tell you rpm while in car tach dont work .

I guess if you haven't got a working tacho then it's hard to nail down. But you can use AFR's if you're measuring them in conjunction with boost to confirm or deny injection quantities.
Basically compare known AFR with a reasonably well know air flow rate and see how the expected fuel flow fits with that.

How much temp you drop across the turbine depends on how hard the turbine is working, how hot the incoming gas is, what the pressure difference is across it and how efficient it is at that point. Soo many variables as to make post turbo temps not much use.