Daydreaming a 1.9 TDI for land speed racing - help me dream, please.

[RabbitJockey]

I think to have the TDI torque down low you will need a trans with a gear so tall it would be impossible. If you are worried about the 1.5 being able to pull at the high rpm then I would be worried about the TDI more. My TDI actually pulls better at 2,000 rpm than at 4,500 rpm. So you would need a trans that is almost 2x as tall to get it where it pulls best...these are generic figures to illustrate as you would not need a trans quite that tall but I think you will want the idi diesel rev range is the point.
if you have a aaz and it hits peak torque at 4,000 rpm or so it would be more suited for what you want. Also why I think the possible idea of the 9a 2.0 is a great idea if it works

...or, I could just run on 43" tall tires.

you would never set a record at 2k, but it'd be interesting to watch someone try.

[theman53]

I have heard of the torque killing salt flats and think the better reving engine with equal power will be your best bet. Put a gov modded landy pump on an aaz and see what you do. Or try the same setup on an alh. If you build a TDI like that 10.7 second one great, but I don't know if getting up to speed is as important as maintaining the speed. The higher rpm torque is in theory what is needed. If the 10 second TDI could maintain that speed over 3 miles then obviously it is the way to do it. I just don't think it would be as easy as with an idi diesel. I would love to be wrong though.

[Jetmugg]

I'm not familiar with a 10.7 second TDI, although it sounds like it's very quick for a 2 liter diesel.  I'll have to do a little searching.

You are right, this is not a drag race.  It's not about elapsed time, it's about coming to equilibrium between power at any given speed, and the combined drag trying to hold the vehicle back at that speed.  As long as you can apply power in excess of the drag, you will continue to go faster.  When the drag equals or exceeds the available power at any point, you have reached your terminal velocity.

Budget-wise, if this 9a bottom end deal would work out, it might be the cheapest way to have a go at the 2.0 record.

If the budget went out the window (i.e. winning the lottery tomorrow), then all kinds of options open up.

Steve.

[theman53]

I didn't watch the video it may have been 11 second, but it was the Pakistan member on here that posted it. It is definitely impressive but this is not a sprint. I know Crsmp box on wheels pulls well but you can feel it tapering off in the end of the rpm. I have ridden in it and yes it is still pulling but not ad hard as it does off bottom. Could be turbo could be head could be the nature of the TDI. The sad part is no one will know until it is tried.
I don't care which way you go as long as you try it. This is awesome even thinking about it.

[Jetmugg]

Dreaming doesn't cost a thing.  Right now, I'm thinking that when I go to Bonneville next August, I'll be taking at least 2 engines, and 3 or more transaxles.

I have a spare AAZ head (bare) that I'm thinking about either porting myself, or having someone who knows what they are doing perform some porting on.  I could then transfer my existing valvetrain to the ported head. 

I have a couple of local guys with 9a parts, and think I'll hit the junkyard on Sunday morning to scope out any more possibilities.

Steve.

[CRSMP5]

take to pm and discuss theman's head with him...

1/4 mile = gear ratio to get you to end the fastest..... 3 mile = gear ratio to make you go max speed... huge differance in goals.............

a 10 speed sequintal box mated to a 1.5na that shifted so fast.. would do a 1/4 mile in 10 sec... but cost prohibited... why big hp with smaller gears costs less...

it a balancing act...

lucas i know my turbo its restriction... it will pull much more with a old set up.. tdi turbo = joke... but for how ive abused it.. kinda impressive too..

[8v-of-fury]

I think to have the TDI torque down low you will need a trans with a gear so tall it would be impossible. If you are worried about the 1.5 being able to pull at the high rpm then I would be worried about the TDI more. My TDI actually pulls better at 2,000 rpm than at 4,500 rpm. So you would need a trans that is almost 2x as tall to get it where it pulls best.

The TDI has torque down low because of its injection, displacement, turbo and head differences over the 1.6/1.9 idi's. Not solely because it is Direct Injected. I have two 1.9's here for quantification, both installed in mk1's with similar transmissions. Both TDI and IDI 1.9L with the smaller GT-15 and K03 respectively, perform identically. Obviously I have more fuel with my 11mm DI over my brothers 9mm IDI, but the performace ie. torque curve and peak feel identical, other than amount of power available.

SO, Lucas. Whatever you have done to your 1.6 IDI would be EXTREMELY more awesome when done to a 1.9L DI engine... they are similar engines, their differences lie in the ability to burn fuel quicker and better with the DI which results in more power delivery.

[theman53]

I will bite...
Show me some dyno sheets to prove it. They don't have to be your dyno sheets but any from a TDI explaining what you stated.
Every TDI dyno no matter who tunes or what turbo it has had peak HP at a lower rpm than what the idi's I have seen. It is easy to find a TDI dyno. this is the only AAZ dyno I have found. look at the end of it to find the graphs

http://www.youtube.com/watch?v=gKXXVIsEtWo

I think just as you do about some of this, the TDI is more efficient and can deliver more power, but for this we are not talking about power, drag race, and efficiency. It is about where the power curve is in the RPM range vs air/land/tire drag, drivetrain loss, etc. So the terminal velocity so to speak of where the engine makes power vs all it is up against. If you build a TDI that has peak power of 300hp at 3,600 rpm and 250hp at 4,400rpm or an IDI that makes 250hp peak at 4,600rpm ...same trans/car etc I think the IDI would have the advantage even though the TDI is making 50hp more. I could be wrong, but then again the record is set right now with an AAZ so I may not be.

[libbydiesel]

An AAZ and AHU will have a similar torque curve if both are fitted with K03/GT15 because those turbos are too small and become a significant exhaust restriction by 3500 rpms even at stock boost pressures of 8-10psi.  If fitted with a more reasonable turbo, the AAZ will continue to pull higher in the rpms than an AHU will. 

Power wins the race.  Torque = Power X RPM.  TDIs make more torque lower in the rpms than IDIs.  IDIs make more torque in higher rpms after the torque has dropped off in the TDIs due to combustion properties.  Because of the prior equation, an engine that makes more torque at higher rpms will result in more power.

[Jetmugg]

Yes, by definition, more torque at higher rpm's is desirable.  In general, the LSR guys are looking for power at elevated rpms, as opposed to "stump pullers" at lower rpms.  Overall final drive gearing and tire diameter are often limiting factors. 

Given a choice between a taller gearset with smaller tires, or a lower gearset with taller tires, the tall gears/short tires typically win out.

I know that for my current configuration, I spent a lot of time with a spreadsheet, calculating final drive ratios, tire sizes, and engine rpm's that suggested what I thought would be a workable rpm range.

Stepping up to the 2-liter diesel truck class means a jump in the record from 106 mph to 130 mph.  I'd like to use the same tires, so that is probably going to mean a taller overall top gear.

[8v-of-fury]

Is the TDI not at this time in the world still the one making quite a bit more power reliably?

Are we at the stage where the idi is capable of making the same power levels as reliably without precup destruction??

[8v-of-fury]

Like from a real world standing viewpoint. Not max power and not all theoretically on paper.

Real world stuff. Which one wins?

[Jetmugg]

I'm not looking to build a daily driver/reliability/long lasting engine.

All I can say is that the current recordholder in the G/DT class (2-liter Diesel Truck) used an AAZ in a Dodge D-50 pickup.

This was not a daily driver vehicle - it was built for the purpose of setting a land speed record for this class.

The record was set in the real world, at Wendover, Utah. 

[8v-of-fury]

Oh no I agree. Not a daily.. but will it make the 3 miles wot oushing that power??

[RabbitJockey]

Like from a real world standing viewpoint. Not max power and not all theoretically on paper.

Real world stuff. Which one wins?

tdi wins in my opinion.  but i think they are both more capable in each others territories if modded properly.  i think a tdi can certainly make upper rpm power... maybe it takes a reshaping of the swirl in the intake port, or the proper combo of injectors/pump, and i think its possible that idi can make great power if the precups are modded to be moving more fuel, like lucas has had done on his 1.6 build.  i think that expecting precups designed to make 70 crank hp to make anything close to 200whp is asking alot... so its not such a surprise that they fail.