Daydream - building a 1.5L CR engine.

Jetmugg · Nov 5, 2011

Possible to de-stroke a TDI to get under 1.5 L displacement?

I'm somewhat new to the VW diesel world, but have a decent amount of experience with MB diesels.

I'm researching the possibility of how to build the most available power from a VW turbodiesel engine, while keeping the displacement at or below 1.5L. This is for a racing application where the class I want to run is 1.5L or less. (H-class land speed record)

I know about the older generation 1.5L IDI diesels, and the 1.6L IDI turbo diesels, but I'm curious about the possibility of creating a TDI-based 1.5L engine.

It would be great to hear from anyone with experience, knowledge, or crazy ideas about how to build the most possible power from 1.5L or less, using a VW-based diesel engine.

Thanks,

SteveM

devonutopia · Nov 5, 2011

What about tuning the hell out of a 3 pot 1.4 TDI?

Its 3/4 of a PD130 TDI and with those tuned up to around 250whp, in "theory" a 3 pot could be around 180whp?

Jetmugg · Nov 5, 2011

Sounds promising, but we don't have the 1.4 in the USA. I suppose importing one might be possible, but costly.

ch0psh0p · Nov 5, 2011

it would cost less to import one then to modify a 1.9 for sure.

http://www.ebay.co.uk/itm/2009-VW-P...arts_Vehicles_CarParts_SM&hash=item3f0f2ec169

Talk to RyanP he may be able to take care of this for you. He imports lots of stuff for us.

TDIMeister · Nov 5, 2011

Neither is there a <1.5 TDI in the USA. Either way, you'll need to build a Frankenmotor put together with Euro-sourced parts-bin components. You can get 76.5mm TDI pistons from the 1.2L 3-cylinder engine, combine it with an 80.5mm crankshaft from the newest 4V CR 1.6 TDI (I've read that the rods and some other components are weak spots, but these would be custom pieces in a highly modded engine anyway). Alternatively there's the 80mm crankshaft from the much earlier 1.5 naturally aspirated IDI diesels. You'll get 1480 cc with an 80.5 mm crank or 1471 cc with an 80mm crank. You could ostensibly get to your 1.5 L displacement target only through a custom de-stroked crank down to 75.5mm max (that's a 20 mm reduction from the original 1.9 crank) and correspondingly longer rods. No reason why it can't be done.

TDIMeister · Nov 5, 2011

What is really nice about a straight de-stroke to an exact 1500 cc displacement is that if you use stock 19.5 compression pistons and retain the same protrusion height and clearance volume, you'll get an automatic reduction in the geometric compression ratio to 15.6. You need this reduction with extreme boosting for extreme power. Done by someone who knows what he's doing, 300 HP should not be ruled out.

I would use better pistons with oil cooling ring channels though like those used in the ARL PD150.

Fix_Until_Broke · Nov 5, 2011

By destroking the 1.9 and leaving the bore the same, the rod ratio becomes favorable for higher RPM operation. The volumetrics also become "better" with the lower displacement on the same size valves/ports/etc.

De-stroking would definately be the way to do this - don't go for a smaller bore. If you're de-stroking anyway, going bigger on the pistons and de-stroking more would be best in my opinion

How many HP were the 1.5L turbocharged F1 racers getting back in the day (on gasoline).

mk3pd · Nov 5, 2011

There is a European 1.6 gasser crank with 77.4mm stroke which fit the ALH style blocks
But even with a 79.50mm bore/77.40mm stroke it will be more than 1500cc.so even this crank needs to be destroked down atleast 2mm
+ custom rod lengths,big end diameter and bearings are needed

This crank also has 4 counterweight which is not the best for this application.

So like mentioned above,using a 1.4liter 3cyl will be the best choice IMO
Can be bored out to 81.50mm and get 1494cc
Use allready available stronger rods,bigger nozzles etc

The engine is also lighter than the 4cyl

TDIMeister · Nov 5, 2011

A triple would certainly have advantages concerning weight and being an ideal layout for pulse-turbocharging.

I hate to rain on a newbie's parade but after 12 years of being here, I've become a little jaded at grandiose project proposals -- 9 times out of 10 they go to nothing and we never hear of the project or the member again -- so my guard and skepticism filter are jacked rather high from spending too much time and thought until I see something of more substance and commitment. Big, ambitious projects are huge money pits and consumers of time, no matter how one thinks they can cut corners.

Jetmugg · Nov 5, 2011

My first thoughts were old-school (a 1.5 IDI rotating assembly inside a 1.6 IDI turbodiesel block). That could be done pretty cheaply, but what I'm trying to find out here is if there are more modern ways to get a turbodiesel VW of under 1.5L to make good power. I think that 200 HP would be more than enough to allow me to reach the goal I'm looking for. 150-175 would probably get the job done.

TDI Meister - I know where you are coming from. Right now, I'm doing the internet research to see what is possible before spending any money. I'm not trying to cut any corners, I'm trying to learn as much as possible before creating a money pit. I've been "around the block" with plenty of automotive and marine projects as well. Some see the light of day, others die on the vine, and some get sold off for a loss after money is spent.

Any idea whether the early 1.5L crank will work inside a "late model" TDI block? I'm not yet up on all the different block and component designations, so please excuse my lack of specific identifiers for the engine series.

The current record in this class is 105 mph, set by a Rabbit diesel pickup. I hope that with a little more modern thinking, that it might be possible to increase that record.

SteveM.

TDIMeister · Nov 5, 2011

Even if you could use the 1.5D crank in a late-model block -- I suspect journal diameters are different and the free-end nose was a major problem of early Diesels with a woodruff key and was subsequently improved in the TDIs with a tapered nose fit -- the 80mm stroke would put you over the 1.5L displacement limit with 79.5mm pistons. Also, I expect a 30+ year old crankshaft to be significantly inferior in material specification and other detail design things.

The PD bottom ends were further strengthened and improved. If you want to go to a de-stroke, I'd suggest to start off with a PD short block, weld proper alloy steel material on the crankshaft journal, grind to the new stroke, relieve, lighten, balance, shot-peen then nitride. 164 mm con rods is the same length as the early VR6, but end diameters and thickness will be different.

105 MPH should be easy to break. Put the engine into a light, aerodynamic chassis, like a Corrado or kit-car from Smyth Performance or K1 Roadster.

DPM · Nov 5, 2011

Why VW even? Something like the Toyota 1.4 D4-D pushes the new Yaris to 108mph, right out of the showroom...
1364cc/90bhp. Search 1ND-TV if you're interested...

TDIMeister · Nov 5, 2011

Because he's in a VW forum.

DPM · Nov 5, 2011

not too many other forums to choose from tho, really...

Jetmugg · Nov 5, 2011

It has to be in a truck body as well. This will be in a Dodge Rampage, which qualifies as a truck, along with the Rabbit Pickup, S-10's, Rangers, etc. The fact that early Omni/Horizon chassis (same as Rampage) came with 1.7L VW gasser engines and trannies simplifies the installation.

Jakobicev · Nov 6, 2011

Isn't there also a factory VW 1.7 SDI engine out of euro Polo,Lupo or Seat Arosa?
Cylinders: 4, in line
Valves per cylinder: 2
Capacity: 1716 cm3
Bore x stroke: 79,5 x 86,4 mm
Compression: 19,5:1
Max power: 44 kW (60 hp)
Max power RPM: 4200 rpm
Max torque: 115 Nm
Max torque RPM: 2200 rpm
Fuel system: direct injection
Engine type: ohc

Maybe easier to de-stroke to 1.5l?

devonutopia · Nov 6, 2011

I still say import and mod a 3 pot up, rather than really faffing about getting a larger displacement down.

Should be able to pick up the whole front end, and wiring, from a 1.4 TDI for not too much. Not especially sought after locally compared to the 1.9 stuff, especially for tuning. Would be pretty cool to have the only 3 pot derv in the US as well

AndyBees · Nov 6, 2011

I never read all the responses ...............so, just off the top of my head, here is a suggestion:

-sleeve a 1.9 down to something smaller than a 1.5 which is a 76.5mm bore.
-machine a set of 1.5 pistons to mimic the 1.9 TDI pistons.

You'd have to run the numbers, because the 1.5 has a shorter stroke.....even shorter than the 1.6 IDI engine. It may be possible to modify a 1.5 or 1.6 crankshaft to fit the TDI block ......just don't know!

Fix_Until_Broke · Nov 6, 2011

If you're displacement limited by rules, you generally want to run the largest bore, stortest stroke that you can and spin/boost the daylights out of it. The larger the pistion diameter, the larger valves you can run which means less shrouding, more flow area, more airflow compared to a small bore/large stroke of the same displacement. You also end up with a compression ratio advantage as TDIMeister said (for a turbo diesel) and a rod ratio engine geometry advantage within a given package size for higher RPM operation.

TDIMeister · Nov 6, 2011

As with most technical decision-making, nothing is clear-cut and there are compelling pros and cons to either a triple or 4-cylinder and, which is better in the final analysis will be made clear and dictated when the problem, objectives and budgets are better defined. Boxing yourself in to absolutes at this early stage limits your options and obscures the potential best solution.

akafred · Nov 6, 2011

http://www.kingscrankshaft.com/kings_crankshaft_llc_008.htm

they should be able to make some rods and crank to your specs..

v8 coupe · Nov 6, 2011

could you just put a 1.9L head on a 1.5L bottom end? Maybe not an ALH but what about an AHU head?

Then do a little reworking of the pistons to get a bowl design that might work better. would you use a mechanical IP or electronic?

andy2 · Nov 6, 2011

Jetmugg said:
My first thoughts were old-school (a 1.5 IDI rotating assembly inside a 1.6 IDI turbodiesel block). That could be done pretty cheaply, but what I'm trying to find out here is if there are more modern ways to get a turbodiesel VW of under 1.5L to make good power. I think that 200 HP would be more than enough to allow me to reach the goal I'm looking for. 150-175 would probably get the job done.

TDI Meister - I know where you are coming from. Right now, I'm doing the internet research to see what is possible before spending any money. I'm not trying to cut any corners, I'm trying to learn as much as possible before creating a money pit. I've been "around the block" with plenty of automotive and marine projects as well. Some see the light of day, others die on the vine, and some get sold off for a loss after money is spent.

Any idea whether the early 1.5L crank will work inside a "late model" TDI block? I'm not yet up on all the different block and component designations, so please excuse my lack of specific identifiers for the engine series.

The current record in this class is 105 mph, set by a Rabbit diesel pickup. I hope that with a little more modern thinking, that it might be possible to increase that record.

SteveM.

Do you know if the current record holder had any engine modifications? Is it mabye just as cheap and simple to turbocharge a 1.5 IDI with a moded 1.6TD pump.If you are only looking for an edge over a 1.5 NA powered truck then I don't see why a turbo'd 1.5idi couldn't make 150 hp.Might not last for more than one run but it likely would get you the record.

devonutopia · Nov 6, 2011

Fix_Until_Broke said:
If you're displacement limited by rules, you generally want to run the largest bore, stortest stroke that you can and spin/boost the daylights out of it. The larger the pistion diameter, the larger valves you can run which means less shrouding, more flow area, more airflow compared to a small bore/large stroke of the same displacement. You also end up with a compression ratio advantage as TDIMeister said (for a turbo diesel) and a rod ratio engine geometry advantage within a given package size for higher RPM operation.

How about getting one of the latest 3.0L TDI V6 engines and simply "half everything" ?

DPM · Nov 6, 2011

cause it wouldn't fit FWD engine mounts?

devonutopia · Nov 6, 2011

DPM said:
cause it wouldn't fit FWD engine mounts?

I see my English sense of humour has fallen on deaf ears.

Matt-98AHU · Nov 6, 2011

Fix_Until_Broke said:
If you're displacement limited by rules, you generally want to run the largest bore, stortest stroke that you can and spin/boost the daylights out of it. The larger the pistion diameter, the larger valves you can run which means less shrouding, more flow area, more airflow compared to a small bore/large stroke of the same displacement. You also end up with a compression ratio advantage as TDIMeister said (for a turbo diesel) and a rod ratio engine geometry advantage within a given package size for higher RPM operation.

You're not technically wrong, but short strokes don't make so much sense with diesels. It's very limited by how fast the fuel can burn, even full on diesel-powered Le Mans race engines don't exceed 6000 RPM AND they've already passed their horsepower peak by that point.

A longer stroke makes sense to allow proper time for a complete burn of diesel fuel plus it has a leverage advantage for more torque. With a diesel, a big bore short stroke setup really isn't going to gain you much, IMO.

Makes GREAT sense for gas racing engines, however. Oversquare engines are the name of the game in Formula 1 where, before regulations imposed a mandated rev limiter at 18,000 RPM, they were capable of more than 20,000 RPM! Not very high torque engines, but since they revved so high and were able to produce enough torque at those RPMs, the horsepower figures are quite impressive. Plus you just shorten the gearing so you get more torque multiplication to the wheels and you have a recipe for manic acceleration.

My vote is on a European-sourced 3 cylinder.

Jetmugg · Nov 6, 2011

I think the most practical and cost effective thing is going to be to put an early 1.5L rotating assembly into a 1.6L turbo block, max out the pump, fit a bigger turbo, and run an intercooler. The reason for the 1.6L block over the 1.5 is that the 1.6 turbo blocks were equipped with oil squirters for the pistons, used bigger head bolts, and are generally considered "tougher" blocks.

If I were to import a 3 cyl TDI from Europe, what else would I need (wiring harness, ECM)? I'll assume for the time being that the 3 cyls will bolt up to the commonly available transmissions in the US. Unless someone tells me otherwise.

manual_tranny · Nov 6, 2011

I don't know, I think the secret to getting high hp with a diesel (with current technology) is finding a way to get them to higher rpm, even if it means sacrificing some efficiency of burn.

It makes more sense to find a good common rail setup though, because the injection timing and quantity will be hard to tune at high rpm with traditional solenoid pump systems. I'll never run my VE pump much past 5200rpm.

What we need is for someone to design a fuel pump that is reliable at 9,000rpm.

Also, it would be nice if there were two bowls and two injectors per piston.

TDIMeister · Nov 6, 2011

Fast, cheap and practical. Pick two.

Daydream - building a 1.5L CR engine.

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