ka24e to sd25t 4x4 swap

[ehtrain]

very interesting stuff given propane is 120ish OCTANE and diesel is CETANE(the opposite on the scale). Amazing how LPG works in a diesel If I can get my engine to stay running...cough..cough... ill look at propane for sure. Ever since I was young kid interested in vehicles and watched stacey david from "trucks" put a propane system on a ford I think it was. I've always thought about doing it. I tried doing some research before I turbo'd and info seemed very hit and miss. I found a few systems that used nitrous and propane. I like the idea but thats getting pretty intense for parts and expensive failures if anything happens without all the knowledge required for setup and maintenance..etc...etc... the VE injection pump would seem well suited for this type of testing given it doesnt need a throttle blade..... hmmm maybe thats a good spot for fogger nozzle after the throttle shaft is removed....

thought also occurs... what about actually using an impco mixer and the vapourizer? instead of just the vapourizer. the factory mixers are adjustable like a carb. maybe run one pre turbo with a secondary flange mounted on?

[waynosworld]

very interesting stuff given propane is 120ish OCTANE and diesel is CETANE(the opposite on the scale). Amazing how LPG works in a diesel If I can get my engine to stay running...cough..cough... ill look at propane for sure. Ever since I was young kid interested in vehicles and watched stacey david from "trucks" put a propane system on a ford I think it was. I've always thought about doing it. I tried doing some research before I turbo'd and info seemed very hit and miss. I found a few systems that used nitrous and propane. I like the idea but thats getting pretty intense for parts and expensive failures if anything happens without all the knowledge required for setup and maintenance..etc...etc... the VE injection pump would seem well suited for this type of testing given it doesnt need a throttle blade..... hmmm maybe thats a good spot for fogger nozzle after the throttle shaft is removed....

I also have a VE type injection pump on one of my engines, I thought it would be the best way to turbocharge one of these SD engines, till I met Larry on craigslist, you see I bought a turbocharged SD25 engine out of the mud on the side of a guys house one day, it had a homemade turbocharger on it, someone had welded the factory exhaust manifold outlet up, and cut a new hole in the side near the front, well Larry advertised wanting a SD series exhaust manifold so he could do just that, I sold it to him and at the same time showed him mine, he wanted to buy it, but I told him I would not do it that way, I told him I would do it with a sharp curved pipe from the stock outlet, and that is what he did, when I went to look at what he had done, he sold me back the exhaust manifold for $23.00, I sold it to him for $25.00, it's all I had on me.
The way he had it at first without the propane is a very good starting point, it freaking worked the first time, you know how many guys have tried doing this and failed, admittedly most failed because of using to big of a turbocharger and were not able to build any boost over one or two pounds, I have read a lot of them, and they all just disappear and are not heard from again, they are all SD22 engines also.
I bought this setup for two reasons, one is that it worked, the other is that all the research was done, all the parts were bought, all the mods were done, and I sort of understood it and figured I could copy it, at least I could copy what was done before the propane injection part, as it was a daily driver, and for the limited time I knew Larry, I kinda got the idea that this guy was really smart, and listened to others ideas if they made sense.
Thinking about it, I don't think that the propane could be recirculated using the BOV, as when the BOV did it's job, the propane would continue to pump in propane in a circle until one gave it the pedal, and by that time it might be to much propane at once, so recirculating would not work with this design, but if he had not sold it to me, he might have continued to evolve to the point of injecting it after the throttle blade/intake manifold, I bet he could have figured it out, and that is are loss.

[elminero67]

I'm curious as to how well that contraption worked and how long it lasted?

[waynosworld]

I'm curious as to how well that contraption worked and how long it lasted?

Are you talking about the contraption in the photo I posted?
I looked it over a lot after I bought it, after I had the engine running on an engine stand with a stock intake/exhaust, I put it back on and tested it, it ran like the stock setup, it might have revved a little faster, it was hard to tell.
But the former owner had done something that was a sign of an issue, the same issue that all the other attempts at turbocharging an SD22 I have seen had, they were all unable to build any boost because the turbo was to big, and I think this setup had the same issue, because the waste gate was wired closed, you can see the wire in the photo.
There were two of these SD25 crate engines bought from Nissan at the same time, one went into a Datsun 521 which had a pole building collapse on it with several other collector vehicles when to much snow gathered on the roof 5 or so years ago, and the other was put into a Datsun 620 and drove for years until the owner died, and the kids pulled the drive train out of it, and scrapped it because it had rusted beyond repair, this is the engine I bought.
I thought with the waste gate wired shut that it was not worth chasing, so I never put that setup in my diesel truck, as it drove fine without the turbo compared to all my SD22 engines, I can drive 80mph all day long on level ground, so I just left it alone and played with my many other projects.
Fact is it is goofy looking with the exhaust outlet welded shut, and the new outlet in the front with all the runners pointing towards the rear, it must have had shit flow having to go backwards in that exhaust manifold and then having to make a 90 degree turn just to get to the turbo vane.
Larry was going to do the same thing, he came over to my house and bought an exhaust manifold from me to do just that, seen mine and wanted to buy it from me, but I told him I would not do it that way, and told him how I had seen someone on here do it with a curved pipe from the stock outlet, and he went home and did just that.
By the way, the turbo Larry used is a lot smaller than the turbo on the setup in the photo, and it works great, at least that is what Larry tells me, I don't drive this Volvo because it's not in my name, and I plan on scrapping it, so it will never be in my name, so I don't drive it, I will transfer the drive train into a 720, or whatever vehicle I decide to build for it.

[elminero67]

that's what I was looking at-the welded up exhaust manifold with at least one of the cylinders flowing backwards against the direction it was intended. I imagine it did not optimize performance, but also wonder if the uneven backpressure would lead to head gasket failure-or worse.

I know you keep mentioning that you believe that too big of a turbo is one of the issues, and I struggle trying to understand that concept: In my mind, you are confusing volume with pressure. It may have a slightly slower windup if it is too big (the one I will be using is for a 2400cc gas motor vs the 2300cc diesel), but I don't understand how you feel that is what is leading to the failures we have seen with turbos on the SD series motors.
Not trying to be argumentative, just trying to understand before installing on my new SD23.

[waynosworld]

that's what I was looking at-the welded up exhaust manifold with at least one of the cylinders flowing backwards against the direction it was intended. I imagine it did not optimize performance, but also wonder if the uneven backpressure would lead to head gasket failure-or worse.

I know you keep mentioning that you believe that too big of a turbo is one of the issues, and I struggle trying to understand that concept: In my mind, you are confusing volume with pressure. It may have a slightly slower windup if it is too big (the one I will be using is for a 2400cc gas motor vs the 2300cc diesel), but I don't understand how you feel that is what is leading to the failures we have seen with turbos on the SD series motors.
Not trying to be argumentative, just trying to understand before installing on my new SD23.

I am not sure I can completely communicate what I mean to you about the turbo, but I have seen and read a lot of builds that used a turbo that was made for a gas engine of the same size, and none of them could build more than a couple pounds of boost if any boost at all, I consider these builds as failures, I would also consider having to wire the wastegate wired shut a fail also, it might have ran just fine, but I highly doubt it had any more power.
The turbo Larry used was made for a VW, it is small, made for somewhere around a 1600cc engine, the engine he was using was a SD25 Nissan diesel, diesel engines don't turn the RPMs that gas engines turn, so the turbo has to spin up a lot sooner, actually under 2000rpms, I don't believe that you will get a T25 type turbo to spin up at that low of a RPM, there is just not enough air to get it spinning.
It's kinda like blowing on a fan blade, a small blade I can blow on and make it spin really fast, but a bigger blade will not spin that fast, because I don't have lungs big enough to blow that hard, these small diesel engines are not big enough to turn a big turbo like a gas engine can at 5000rpms, I don't know how to explain it any other way.
I did not install that turbo setup on my engine for a couple reasons, it looked like a failure to me because of the way they cut into the exhaust manifold, and the wastegate was wired shut, which makes me think it would not build up boost, but it was on this engine when I bought the engine, but I was so happy to have an SD25, that I didn't care if it had the turbo, as it had way more power than my SD22, if it had been as gutless as my SD22, then it likely would have had a turbo by now.
I agree with you about the exhaust manifold, it had 3 cylinders that had to push the exhaust out backwards, and all of the exhaust had to make another 90 degree turn just to get to the turbo vane, it doesn't look like it would work very well, that is one of the reasons I refused to sell it to Larry when I met him.
I would talk to someone that knows a lot about turbos for diesel engines before I invested a lot of time into that big of a turbocharger, I have been thinking and reading about this for several years, and in all them years I have not seen one successful, streetable, daily driver, turbo diesel that worked properly, mind you I do not know if the one I bought from Larry is successful yet either, I have only drove it once because it is not in my name, and it looked like it was getting really hot(EGTs) if I tried to go faster than 55mph, it was a hot day, the intercooler(not connected) was directly in front of the radiator(no radiator fan), and the temp gauge on the dash was almost pegged, the EGT was running really high, so I turned around and got it back home without boiling over and parked it, after the EGT was below 400 degrees I shut it down and have not started it much to warm it up since, the battery was actually dead yesterday, so there is a draw somewhere, so I had to charge it up to start it today.
I don't know if this setup is a success either, but I plan on finding out this summer/fall.
I am not capable of short replies, I have to cover all the angles/bases.

[ehtrain]

that's what I was looking at-the welded up exhaust manifold with at least one of the cylinders flowing backwards against the direction it was intended. I imagine it did not optimize performance, but also wonder if the uneven backpressure would lead to head gasket failure-or worse.

I know you keep mentioning that you believe that too big of a turbo is one of the issues, and I struggle trying to understand that concept: In my mind, you are confusing volume with pressure. It may have a slightly slower windup if it is too big (the one I will be using is for a 2400cc gas motor vs the 2300cc diesel), but I don't understand how you feel that is what is leading to the failures we have seen with turbos on the SD series motors.
Not trying to be argumentative, just trying to understand before installing on my new SD23.

I can possibly shed some light on your questions, and some of it has already been answered in above post. in terms of manifold "flow" yes 1 cylinder would have poor flow as it would have bends this would slow down the velocity of the exhaust from that cylinder and would also reduce the amount of exhaust that can flow and be scavaged out. if you were to put and egt gauge on each cylinder as with any manifold with unequal length runners you will see performance difference in each cylinder in terms of temp and volumetric efficiency. Thats the reason why performance manifolds are equal length runners. this corrects the flow across to the same level on all cylinders trying improve the power the most and create the most scavaging effect between exhaust pulses (yes exhaust comes out in small pulses not a stream) this is why I created a "J" pipe for my turbo as this helps the manifold flow the most like stock while not creating sharp bends or incorrect flow patterns.

ok and to answer your question on turbo gas vs diesel. It's all about volumetric efficiency. gas engines are not very efficient and require the fuel and the incoming air to be metered. energy can't be destroyed it can only be transformed. gas turns about 60-70% of its energy into coolant heat and unburnt fuel. the other 30% is used to move your vehicle. Add a turbo - more air means more fuel means more power. however do to this inefficiency there are larger exhaust volumes. so a turbo needs a larger turbine to handle the output as well as the input air. gas also has a larger rpm range to play with requiring a turbo with a larger capacity.

diesel turns roughly 40% of its energy into waist like coolant heat and exhaust heat. meaning approx. 60% of the fuels energy is used to move the vehicle. this is why diesel is generally a more efficient motor. it comes down to how it works and fuel it uses. and diesel does not need a throttle blade like a gas. so the turbo has a physically larger area to cover over the gas as it has to maintain pressure against the intake valves at all speeds. where a gas engine will not build boost until the throttle is opened allowing more flow. so because diesel has a slightly increased air demand and decreased exhaust volume the turbo needs a smaller exhaust turbine to make up for flow speed. this is why diesel projects like mine suffer "turbo lag" from an over sized exhaust turbine. diesel also redlines around 4-4500rpm on IDI engines. so your rpms range is very limited in comparision to say 6-9000 for gas. thats generally why you see a diesel turbo with tiny exhaust turbine and larger compressor. a good model of this here locally is if you own a diesel at -30c it idles all day unless your plugged in. even then you might have to idle up to 1700rpm or so to keep the engine warm enough it wont carbon up or let the oil cool down to much making for hard re-start. lots of us switch to thinner oils to reduce the friction and effort it takes to pump cold oil on start up. diesel is efficient enough the engine could be hot when you park it and let it idle for 20 min and come out to see the temp gauge on cold again unless its idled up. a gas engine let it idle for 20min at -30c your temp gauge will go from cold to hot and stay there. it expels more heat in inefficiency then a diesel by significant amounts.

to be honest to the arguement compression is the biggest thing that changes efficiency. gas can get more efficient but you need higher octane fuels (more stable burn). when I was doing the math of flow i found a 1.8L turbo gas motor (ca18det) has similar flow requirments for the sd25 diesel. the gas motor would make probably 225-230hp while the diesel would top out at 150ish if that was possible. there are compressor and turbine maps that combine flow and turbine speeds so you are able to choose the turbo for your application assuming you want to do the math. Garrett turbo's website has a long tech page on turbos and explaining the various aspects. If I recall right gas exhaust speed is high volume but low speed. but a diesel is high speed and low volume. I had a book somewhere explaining all this... by tom grilles i believe it was.

[waynosworld]

Can you post a photo of the "J" pipe again, I cannot find it anymore, it was what I told Larry to make when he came over to my house to buy an exhaust manifold to do the same thing that the old timer did when he made the exhaust manifold I have, it was a stupid way to do it, but it was done a long time ago, before all these forums we have now to help each other, and pass along good ideas.

that's what I was looking at-the welded up exhaust manifold with at least one of the cylinders flowing backwards against the direction it was intended. I imagine it did not optimize performance, but also wonder if the uneven backpressure would lead to head gasket failure-or worse.

I know you keep mentioning that you believe that too big of a turbo is one of the issues, and I struggle trying to understand that concept: In my mind, you are confusing volume with pressure. It may have a slightly slower windup if it is too big (the one I will be using is for a 2400cc gas motor vs the 2300cc diesel), but I don't understand how you feel that is what is leading to the failures we have seen with turbos on the SD series motors.
Not trying to be argumentative, just trying to understand before installing on my new SD23.

I can possibly shed some light on your questions, and some of it has already been answered in above post. in terms of manifold "flow" yes 1 cylinder would have poor flow as it would have bends this would slow down the velocity of the exhaust from that cylinder and would also reduce the amount of exhaust that can flow and be scavaged out. if you were to put and egt gauge on each cylinder as with any manifold with unequal length runners you will see performance difference in each cylinder in terms of temp and volumetric efficiency. Thats the reason why performance manifolds are equal length runners. this corrects the flow across to the same level on all cylinders trying improve the power the most and create the most scavaging effect between exhaust pulses (yes exhaust comes out in small pulses not a stream) this is why I created a "J" pipe for my turbo as this helps the manifold flow the most like stock while not creating sharp bends or incorrect flow patterns.

ok and to answer your question on turbo gas vs diesel. It's all about volumetric efficiency. gas engines are not very efficient and require the fuel and the incoming air to be metered. energy can't be destroyed it can only be transformed. gas turns about 60-70% of its energy into coolant heat and unburnt fuel. the other 30% is used to move your vehicle. Add a turbo - more air means more fuel means more power. however do to this inefficiency there are larger exhaust volumes. so a turbo needs a larger turbine to handle the output as well as the input air. gas also has a larger rpm range to play with requiring a turbo with a larger capacity.

diesel turns roughly 40% of its energy into waist like coolant heat and exhaust heat. meaning approx. 60% of the fuels energy is used to move the vehicle. this is why diesel is generally a more efficient motor. it comes down to how it works and fuel it uses. and diesel does not need a throttle blade like a gas. so the turbo has a physically larger area to cover over the gas as it has to maintain pressure against the intake valves at all speeds. where a gas engine will not build boost until the throttle is opened allowing more flow. so because diesel has a slightly increased air demand and decreased exhaust volume the turbo needs a smaller exhaust turbine to make up for flow speed. this is why diesel projects like mine suffer "turbo lag" from an over sized exhaust turbine. diesel also redlines around 4-4500rpm on IDI engines. so your rpms range is very limited in comparision to say 6-9000 for gas. thats generally why you see a diesel turbo with tiny exhaust turbine and larger compressor. a good model of this here locally is if you own a diesel at -30c it idles all day unless your plugged in. even then you might have to idle up to 1700rpm or so to keep the engine warm enough it wont carbon up or let the oil cool down to much making for hard re-start. lots of us switch to thinner oils to reduce the friction and effort it takes to pump cold oil on start up. diesel is efficient enough the engine could be hot when you park it and let it idle for 20 min and come out to see the temp gauge on cold again unless its idled up. a gas engine let it idle for 20min at -30c your temp gauge will go from cold to hot and stay there. it expels more heat in inefficiency then a diesel by significant amounts.

to be honest to the arguement compression is the biggest thing that changes efficiency. gas can get more efficient but you need higher octane fuels (more stable burn). when I was doing the math of flow i found a 1.8L turbo gas motor (ca18det) has similar flow requirments for the sd25 diesel. the gas motor would make probably 225-230hp while the diesel would top out at 150ish if that was possible. there are compressor and turbine maps that combine flow and turbine speeds so you are able to choose the turbo for your application assuming you want to do the math. Garrett turbo's website has a long tech page on turbos and explaining the various aspects. If I recall right gas exhaust speed is high volume but low speed. but a diesel is high speed and low volume. I had a book somewhere explaining all this... by tom grilles i believe it was.

[ehtrain]

the pipe I used is 2inch radius 2in exhaust pipe. Other then the flanges I believe I used only that pipe with some skillful measuring very little material waisted. I added some bracing across the bend radius to help stabilize and strengthen the pipe. I also added 2 braces from the exhaust manifold heat shield bolt holes to the upper flange area to prevent any twisting or vibrations from exhaust and intake from breaking welds. I also removed the factory donut to the manifold in favour of a flat bimetallic gasket which gave me a nicer flat surface for the manifold to j-pipe flange. I was more worried about function over form with the setup. I would like to make another j-pipe when I go to a smaller tb25 turbo.

[ehtrain]

ok I'll keep this boat motor going with some more pictures now that the engine is back together with all nissan parts. I'm also going to sas (solid axle suspension) the truck. well because sas is cool, it will add more flex, more capability, better engine serviceability, and more lift. I seem to have a habbit of getting stuck facing up hill with 2 tires in the air or ripping my skid plates off the transfer case trying to keep to buddy in his samurai. so I'll kill a few birds with 1 stone. wish I had spent the time doing this to start off.... but oh well such is life, live to learn. Originally I had 4.10 gears (r180a/c200 diffs) when I did my diesel swap I nabbed some 4.37 gear axles (r180a/h233b axles) and I was running 31in tire. With my math 5.13 ratio was closest I could get to stock with a 35in tire from the trucks stock 215/75r15 tire. the speedo seems to be pretty much dead on as it would be stock and I have a nice power increase from the 31's however I do notice the extra rolling weight.

[ehtrain]

the pictures dont seem to post from my first to last so everything is out of order but im sure you can figure it out. my internet is too slow to go back and figure out newest to oldest in order.

if anyone has the h233b rear axle in there truck dont even question its reliability. THEY ARE BEASTLY. the h233b axle makes everything on the dana 44 look like a chew toy. for those who dont know the dana 44 was in mid size to full size trucks and suv's. the h233b is playing with stuff like dana 60 territory (1 ton and up) extremely beefy stuff, specially in a 1/4ton. I was amazed when I set the h233b ring gear beside dana 44. the nissan gear is almost 1in. bigger in diameter and has at least double the gear contact width, not to mention the gear thickness being almost double.

loving the 5.13 gears and 35's. lots of clearance and good power on the highway. running 6psi on stock fuel with hot pipe. I also noticed something interesting. because I was overrunning the engine with 31in tire on 4.37 gears this resulted in higher egt's. With 31's I saw 1100-1200 peak then drop off to 1000f on highway. now with gear change I have not seen the egt get higher then 1000f ever and on highway it drops back to 800f. weird to see a 100-200f drop without an intercooler just from engine load change as a result from gearing. I've also noticed solid axle doesnt seem to rob as much power with the hubs locked in driving in 2wd. the IFS front end always seemed like there was abit of drag slowing you down, which i can only think the cv axles? just more joints and more parts turning I think. either way I'm pleased with my results so far

I should also mention I extended my wheelbase forward approx 2in to make room at the rear of the wheel wells for turning/tire clearances. factory fender is only 33in wide. so I hacked off the front section of the fender and trimmed down the flare to match. as far as I can tell my current hieght is equal to the rear with 3in lift from helper spring and longer shackle. this has not been modified from previous. Also without the body lift I would not have the clearance in the rear to stuff a 35. at some pint if I do further suspension modifications I may remove the body lift. But as currently the accessibility to the engine and other parts it offers is valuable and it also gives me more room to fit spare fuel tank and other things while keep the nice flat d21 bottom... FLAT. so we will see what the future brings haha

[ehtrain]

heres some shots of the front dana 44 as I found it. Got it from a local junk yard who had it sitting partly in a slew for better part of 15 years. just about everything from the knuckle out was junk from rust. ended up using spindles and hubs I foundin the junkyard on an 87 chevy 1500 4x4 with gm10 bolt up front. the "c" out on these are dana. so I got some clean spindles that had a nice seal surface, flat top knuckle, some random axle spacer hardware and a set of super winch hubs for 50 bucks. so that solved all my issues with rusted our spindles on the jeep axle. I put on new brakes, pads, seals, and calipers got reman for 35 bucks each. I left the inner spindle bearings that where in the gm spindles as they were in nice shape as well as the wheel bearings. I also installed new ball joints and axle seals. After looking at the cost of the swap and the availability of parts. I wish I would never have spent the cash fixing the front end in the truck the first time. even with the locker if I had swapped to the stronger r200a front axle and gotten cv axles. I would have maybe spent 500 less. and I would still be dragging the truck through everything needing more lift even if I could stuff 35s and run them with the r200a. now i can just get lift springs and i get more flex. plus i can roll under the truck now and take my oil pan off or take the starter out without a bunch of #%^* happening lmao

[ehtrain]

figured id post some updates that ive done to my frankenstien

[ehtrain]

heres some action shots of the beast. took it to waiparous alberta in the ghost lands offroad area and did about 100km of some very nice trail. everything held up awesome. I cant speak enough about how happy I am with diesel offroad. it never misses a beat and the torque is always where you need it. The little toyotas would have to rev up as they made steep climbs or they would power out. the little sd25 just kept on at 2500rpms it didnt give a shit whether the water was part way up the doors, climbing rank hills, or decending down some very steep inclines on very strange angles.

[ehtrain]

I figured I'd make a quick update. I have added some fuel to the system. I turned the IP fuel screw not quite 1/4 turn. I am again impressed with the results. I have a moderate power gain and I'm seeing my average temp on the egt's drop. even at 5psi and stock fuel I'd peak temp around 1100F. Now I peak around 1200F which should still be in the safe zone. But now the temps drop way back soon as I stop accelerating. I'm doing 110kmh (70mph) at 800-900F which is nice to see. Also around town the power gain is nice I can shift to next gear more often which reduces egt's and rpms. I also see full boost about 200rpms sooner which is also nice to see. So I will turn the screw abit more once I get more feel for the truck and see some mpg results.

I realized also that I forgot to give the reason why my intake valves lost there valve last in previous posts. the valve margin was concaved meaning the valve margin wore into the valve seat. It was noticeable to the eye. Whether it was the valve seats being past hardening or the valve either way they have both been replaced with nissan parts now.