Brand Newbie here - working on a Land Speed Project (1.5L or less diesel).

[Mark(The Miser)UK]

Call me stupid, but what is the difference in peak cylinder pressure, from an engine that has a standard compression ratio of say 22:1, and developing say 150BHP, and a sister engine that has it's compression ratio lowered to say 19:1, and also developing 150BHP

I cannot picture why the same power output doesn't require the same force pushing the piston down, or at least average force...

The same force  being the result of the same overall psi in the cylinder, isn't it

[Jetmugg]

Great discussion guys...  As far as the absolute HP numbers needed to set a new record in this class - I think that 150 HP (from a 1.5L engine) would be on the high side of what's needed.  In fact, I would feel very good if I could see numbers between 125-150 HP at the wheels, spinning the engine somewhere in the 5,000 rpm neighborhood.  This will be tested by running on a chassis dyno.

Some people seem to think that it should be very easy to make this kind of power from a 1.5L VW diesel.  I'm not so confident, that's why I am interested in taking every advantage in building an engine, while trying to keep the cost down.  Keeping the cost down, to me, means using as many factory VW parts as possible.  Custom pistons, custom rods, custom cranks, etc. are all cost prohibitive.   A creative combination of factory parts is within the budget, as long as I can source the parts.

There is no doubt that the 1.9 head will flow better than the 1.5 or 1.6 heads.  I can run any turbo that I want, which should help with the EGT's and the ability to push a lot of air through the head at elevated rpms.  Low RPM drive-ability is not a concern.  The ability to get the engine started is important, however.

The way this effort will work is that the engine will be started, warmed up (even if it's very smoky), brought to the start line, then when the official starter waves me onto the course, the engine will basically be run at WOT for 2-3 minutes straight.  If all goes well, and the vehicle runs more than 105 mph through a measured mile, the vehicle will be impounded overnight, and another attempt will be made to "back up" the record on the next day.

There will be an insulated tank (basically a cooler) in the bed of the truck, full of icewater, which will circulate through the intercooler, and possibly through a water-to-oil cooler as well.  The icewater tank can be re-filled for the "back up" attempt on the second day.

I'd like to raise the record to something over 110 mph, just to have a little cushion.  Depending on the final selection of tire size and transmission ratios, the rpm's that the engine will have to turn through the measured mile will be somewhere between 4600 and 5600 rpm.  5600 scares me, and I don't think 4600 will be enough to make peak HP.  I'll be aiming for a combination that will peak more in the 5,000 rpm range.

[theman53]

Use the ARP hardware for the connecting rods and all other fasteners you can and with the lowered compression ratio I do not think it would be an issue to turn it at 5500rpm for only one mile. If you are going over 100mph then it is less than 40 seconds. That isn't that long. Please again, do not use the same water/ice for the oil cooler as the intake cooler. The rpm limit is more about the pump and you can talk to Giles about that one. These are basically the same bottom ends that VW has put in the high reving gassers that see well over 6,000 all the time.
Like I said if I don't have my engine built you could borrow the aaz head I have. If it doesn't work go buy a 1.6 head and send it to air cooled engines plus in tiffin ohio. My 1.6 head flowed way more and had less tumble than a 1.9 head that he didn't do the port job on. I didn't even have the race port done, it was daily driver port job. He said there was more to be had. He also gives you a flow bench report on your head. I had 600.00 in the entire job rebuilding, porting and shipping.

[Jetmugg]

TheMan - I'm not trying to be difficult, just want to understand the reasoning behind not using the same cooling water for the intake air as for the oil cooler.  I don't have a good feel for what the water temp would be after the intercooler, but I "feel" like it should still have plenty of cooling capacity to cool the oil as well.

I have a friend who is into VW drag racing.  He uses a cooler full of icewater and a livewell/bilge pump to circulate the cold water through his intercooler and back to the cooler.  This is on a gasoline powered 2.0L VW that makes BIG power (running in the 10's across the 1/4 mile) He says that a cooler full of icewater will last him an entire afternoon or evening of drag racing.  Of course, he runs his engine for much shorter periods of time.

Obviously, I have a lot of homework to do on this setup, I'm just trying to learn as much as possible at this stage. 

Again, I really appreciate the offer to possibly use your 1.9 head when the time comes.  I would certainly be willing to take you up on that offer.  Your cylinder head guy sounds like he knows what he's doing, as well.

Right now, my first priority is to get the chassis, roll cage, and suspension worked out on the car before I will need an engine, but I will keep thinking about the engine package and looking for a good deal on the parts that I'll eventually need.

[theman53]

I don't know #s but if you just put intake air into the ice water that is all it will heat that ice water. Oil temps will be between 210 and 260 F depending on how hard you are running, that will heat that mixture more than the intake air alone. You will want the coolest intake air and oil to be as cool as possible but over 180F. If it was a street strip car then yes I wouldn't hesitate sharing the icewater, but this is all out speed and you are looking for the most cushion so I wouldn't cut corners on that. The more cool air you have the more fuel you can put to it and therefore the more power. It maybe only 3-4 HP, maybe only 1 HP, but in your goal I would take every possible HP I could, especially if it is easy like this one.

John at Air Cooled Engines Plus is a genious. He started in the porche/vw air cooled stuff and is a nut, but does everything now. He has a great formual to make the heads flow. He maybe one to hit up for help and you could say he helped in the LSR if you get it.

[R.O.R-2.0]

I don't know what you guys (MJF/ROR) have against lowering compression? It's simple math that you can make more power on lower compression before having any mechanical failure (head gasket/breaking rods/breaking head studs etc).

I like engines that work right, smoky hard starting one is not like that. 150whp (or 180whp) doesn't need lowering compression ratio.

x2..

he hit the nail on the head!

im going to be up around 200hp here soon, with a STOCK N/A long block! (and compounds of course)

[RabbitJockey]

I wish I would have known about when I did my head I spent hours porting it and almost 400 for a rebuild

[AudiVWguy]

Great Thread.
Steve, could you fill in your location so we all know where this cool project is happening.

[Jetmugg]

I updated my location to Festus, Missouri, USA.  There are a couple of sub-discussions starting here, so some of the responses will get a little confusing.  I will try to keep my responses limited to the discussion of a 1.5L "Franken" IDI engine.

  The 1.5L crankshaft has smaller rod journals than the 1.6 or 1.9L IDI engines.    At one time, Saurkraut had proposed using 1.9L rods with cut-down 1.6L pistons in combination with a 1.5L crank.  The larger rod journal size of the 1.9 prohibits this from working without custom bearings, or some other custom parts.

 The piston-pin to piston top surface dimension is greater on a 1.5L piston when compared to a 1.6 L piston.  That's where the difference in stroke is made up.

  I'm definitely still learning while keeping my eyes open for good deals on parts of the puzzle.

Steve.

[UnderPSI]

Jesse Winders has the 1.5 diesel record for the truck class and diesel streamliner class, as well as a couple others. The 1.5 truck record is 3 years old, it's not as easy as it appears on paper.

[Jetmugg]

Yep, Jesse Winders is the current recordholder in H/DT and some other categories.  The Winders team is certainly sucessful and knowledgeable about what it takes to run at Bonneville.  If I'm not mistaken, Mike Manghelli held the H/DT record before Jesse, right at 100 mph, also in a Rabbit pickup.  I believe that Jesse intended to set a new record in the G/DT class, but didn't quite get the engine swap completed in time, based on photos and descriptions I have seen.  If he goes out with the intention of setting a new G/DT record, I would not bet against the Winders team.

UnderPSI - I see your location in Utah, are you associated with the Winders team at all? 

I fully appreciate that breaking the record will not be easy.  That's why I want to explore every option for building 1.5L diesel power that will work at Bonneville.

SteveM.

[UnderPSI]

Old man Winders is a good friend of mine, a very nice guy.

[Aki-76]

Do not lower compression,trust me..
If i built some think like this,maybe i use 1.4 na or 1.3 na base engine.Both engine has several benefit against 1.6 or 1.9

[mystery3]

Do not lower compression,trust me..
If i built some think like this,maybe i use 1.4 na or 1.3 na base engine.Both engine has several benefit against 1.6 or 1.9

Unfortunately the only IDI engines we got in the USA were the 1.5 and 1.6, they have a lot of 1.9 in Canada and a lot more turbo diesels. I think with the limits the OP has on funds for this project importing an engine is not going to be an option, otherwise he'd probably be looking at the 1.2TDI or cobbling something together with the different European TDI engines.

[R.O.R-2.0]

Do not lower compression,trust me..
If i built some think like this,maybe i use 1.4 na or 1.3 na base engine.Both engine has several benefit against 1.6 or 1.9

i wouldnt lower the compression, if the diesel god is advising against it..

we've all been saying not to the whole time, and now that Aki suggests the same, i would NOT even touch compression.