please tell me how to NOT melt a turbo vw

[voodoo]

the question:  if I keep the rpm's below 3000, as in put a governor to limit total rpm to 3000 maximum with engine shutdown over that redline is it possible to melt a 1.6 td?

all suggestions are usefull

I would like to run 20 lb boost with an intercooler

where do I find a governor that gives the motor full fuel to redline but has instant motor shutoff at 3000 rpm? From what I have read the factory parts gradually choke off fuel to 4000 rpm.

[Maarten]

It is possible to melt the engine/turbo below 3000rpm.. you don't need to rev high for high EGTs, just enough fuel or to retarded timing.

I suggest you buy a EGT (Exhaust temp gauge) and mount that on your dash in a pod in you line of vision

[Audi80]

Use bigger turbo, not those tiny KKK14 or KKK03 etc. KKK24, Garrett T03, VNT15/17/20 etc would be good.
Why stop at 3000 rpm? My peak power is at nearly 5000 rpm. 1.6 likes to rev higher.

[Patrick]

Better off running higher revs. Engine is more able to get rid of excess heat if it's moving more air. I'd raise revs more that fuel pressure /boost.

[Master ACiD]

im not convenced its the revs that kills these small diesels.

[fspGTD]

You could switch your VE governor's "car speed" (AKA min/max speed) governor to an "all-speed" (AKA variable speed) to get the near-instant RPM cutoff you as asking about at a variable RPM.  Look for these types of VE pumps/governors on VW Diesel industrial engines.

Descriptions and comparison of both of these kinds of governor are available on-line, at:
http://home.comcast.net/~vwgtd/ve_173.jpg
http://home.comcast.net/~vwgtd/ve_174.jpg
http://home.comcast.net/~vwgtd/ve_175.jpg
http://home.comcast.net/~vwgtd/ve_176.jpg

the basic difference is the car speed governor has multiple compression springs in a capsule, while the all-speed governor has a single tension-type spring with no capsule.

However, if this is for an automotive application (you left out details about how you intend to use this?) then with the min-max governor, throttle response with this setup on a vehicle will be very touchy, You're going to have "all or nothing" torque at any RPM level unless you have an extremely attentive throttle foot.  Due to difficulty in modulating the throttle, this would probably make for very difficult/uncomfortable/high-stress/dangerous driving, especially in bad weather when traction is near its limits (EX: rain, ice or snow on road.)  There is a good reason why VW didn't settle to put the all-speed governor on their passenger cars and went ahead and developed the car-speed (multi-stage) governor.

[voodoo]

fspgdt

full power till redline then instant cut off
I like that idea!  fspgdt you rock!

the plan: a 1.6L 4 cylinder diesel volkswagen in a 1975 rabbit and a 4000 rpm redline

hey buddy wanna race? whats that? you don't like the plastic hub caps?

the car also has a LARGE turbo with 30 lbs boost 300 ft lb tq and weighs 1700 lb.

and gets 40 mpg

I am here asking and reading because I want turbo power but gasoline motors don't like turbos, diesels are perfect for turbo.

[Audi80]

I still donīt understand why you want 4000 redline?

[voodoo]

honestly, what I want is a turbo motor that is designed from the start for abuse, vw diesels are really strong engines and are perfect for turbo's, they can't be hurt by detonation, they run on it!

after looking at the stroke distance, 86 mm/3.4" the piston speed at 5300 rpm is safe, upper acceptable limit is 6200 rpm. 7000 rpm for all out race and don't expect it to live very long, like nascar territory.

its not about rpm's its about preventing the motor from melting.

you are right 6000 rpm is fine.

some vw diesel manifolds are tuned to work at low rpm about 4000 is as far as they go

the correct answer for how to keep a diesel from melting is simple, its the same way turbo gasoline motors are prevented from melting.  compressing a gas generates heat, the more compression, the more heat, the answer is reduce the compression from 23:1 to about 15:1 and add alot more boost and a huge intercooler.  

no I did not just come up with that 15:1 idea, I found it on the description of the mods done to a 900 hp 1500 tq cummins.

when the piston compresses the air in a cylinder it is not easy to cool the mixture but if the turbo compresses the air and then the hot air 400 -F is run through an efficient intercooler returning it to a reasonably cool temperature 120 -F and then the low compression pistons compress the fuel mix, the temperature is lower, hopefully below the temperature that aluminum melts.

anyone know where to find 15:1 diesel pistons for a 1.6 vw?

[QuickTD]

If you lower the compression to 15:1 you will have to push the car to start it, or do like the tractor pullers do and buy starting fluid by the case. The heat loss in an indirect injection engine is much greater than in a large direct injection cummins. Because of this heat loss, it is necessary to run much higher compression ratios in order to produce enough compression heat to insure reliable starting.

 VW diesels don't usually melt down, they tend to break parts due to high cylinder pressure. Head gaskets and probably connecting rods are potential problem areas. Run about 20:1 compression with a thicker steel shim 1.9TD head gasket (if you live somewhere warm), big turbo and intercooler, 25-30psi boost, 12mm plunger in the injection pump to get the fuel in early, GTD nozzles for the same reason, strongest head studs you can find and get a set of custom H beam rods. You should be good for 150hp + with that setup, if you can tune it right.

[Master ACiD]

in the case of an idi engine like these old fashoned diesels we play with, they need lots of compression to aid in starting in cold weather. you probably wouldnt be able to start a 15 or 16:1 compression diesel very easily when its 40 degrees outside.

a tdi could maybe manage it.

[fspGTD]

Sure there is some heat generated during compression and slower RPMs will give it more time for the heat to dissipate into the oil and cooling system than high RPMs, but don't you think there is relatively much more heat coming from that burning fuel inside the combustion chamber?  Especially on a high-boost, high-fueled motor, the heat coming out of the combustion process must be intense!  That said, luckily aluminum in the head and pistons conduct heat away quickly, helping the combustion chamber surfaces stay cool despite above-aluminum-melting-point combustion chamber temperatures.  I don't think heat-generated friction from piston rings (which you'd think would also increase with higher RPMs) would be much of a contributor to combustion chamber temps.

Properly reducing the CR on one of these motors would require basically re-engineering the motor and some intense and precise metal machining/fabrication.  The combustion chamber is partially in the pistons (in that small "cloverleaf" relief) and partially in the head (in the swirl chamber), and the maintain efficient engine efficiency and air utilization (power) you'd need to enlarge those components in order to reduce the CR.  That would actually potentially increase efficiency and power somewhat, but like others have said the engine will become "cold blooded".  While removing the metal to open up these parts, you'd need to leave the right shape and finish behind, and without weakening the structure too much.  Maybe a 1.9 liter head, with larger swirl-chambers, could be bolted to a 1.6l block to easily get bigger swirl chamber volume?

Various folks here (myself included) have tried reducing the CR by increasing the dead area above the piston (IE: thicker head gasket.)  It results in a generally crappier running motor, granted perhaps with lower peak cylinder pressures.  Nothing wrong with some combustion chamber heat and pressure as long as things don't break or melt, IMO!

Aluminum melting doesn't seem to be too much of a problem for these motors as long as their injectors are spraying right and atomizing nicely, so the burning stays in the middle of the combustion chamber and away from the aluminum walls.  So I guess my quick answer to your subject line is, keep your injectors spraying nicely and get old high-mileage injectors spray pattern checked and/or rebuilt periodically.

[fspGTD]

the car also has a LARGE turbo with 30 lbs boost 300 ft lb tq and weighs 1700 lb.

I just re-read this line...  That's awesome!  I can also see why you're interested in reducing CR.  Have any problems with, or done anything to avoid head gasket leaks?  I'd recommend intercooling that 30psi heat blower for sure!

Welcome to the GTD forum by the way.

[QuickTD]

You could switch your VE governor's "car speed" (AKA min/max speed) governor to an "all-speed" (AKA variable speed) to get the near-instant RPM cutoff you as asking about at a variable RPM. Look for these types of VE pumps/governors on VW Diesel industrial engines.

 Ours is a family of diesel nuts. We've stuck a number of different diesel engines in a number of different vehicles over the years, and we hang with a crowd that likes to do similar things. We've been involved in lots of industrial engine (VS governor) to vehicle conversions. One consensus that we've all reached is that a variable speed governor really doesn't work all that well in a road vehicle. The VS governor will attempt to maintain the set engine engine speed regardless of load with very little speed droop. Kind of neat when you're cruising but a bit nasty when you let out the clutch, especially when trying to creep along in traffic. It's usually kind of a bucking, lurching affair. In the interest of drivability I would suggest sticking with something with a bit more speed droop. Something close to the stock setup works pretty decent really, aside from the early defueling. If you were to replace both the main and intemediate springs with a longer spring that had more coils (more constant rate) but about the same or slightly greater initial tension as the stock main spring, you might get the sharper cutoff you desire but with a slightly friendlier low speed performance.

[Cheesetoast]

i am runnign 20 psi with a tdi intercooler in my 93 golf td, i haven't got the egt's over 1400, without the intercooler i could do 1600 with stock boost.