Vlad's rides thread

[vt3.8lt]

yeah thats it i would love to get one but unfortunately its beyond my budget as ive already spent 4k on just parts and a bit of machining of the block it is a shame that there is no us vendors for these there is a few for the buick engines and there only about 1200us witch is a good price for a billet crank and i could justify buying one

[vlad01]

yeah thats it i would love to get one but unfortunately its beyond my budget as ive already spent 4k on just parts and a bit of machining of the block it is a shame that there is no us vendors for these there is a few for the buick engines and there only about 1200us witch is a good price for a billet crank and i could justify buying one

yeah big market over there you see for old school buick.

We are one of the leaders in ecotec market and certainly No1 in pre ecotec engines. To the yanks the pre ecotec doesn't exist lol.

Look at how many ecotec parts the US imports from us, all the valve train stuff mainly, crow, rollmaster etc.., even mace sells bits to the US as there is nothing going on in those developments.

[VL400]

What did you use for the sound deadning / insulation on the top of the tank?

Am currently installing a different tank (return line on the current one has broken inside) but the insulation is breaking apart on this new tank.

[vlad01]

You are talking about the alfoil looking stuff?

I bought it from a car audio shop. The one I went to sells one called road kill, but its the same as the popular dynamat and resomat. its a bitumen based self adhesive mat with alloy liner. Same as the factory stuff holden used minus the brand printing on it the factory stuff didn't have.

[VL400]

Thanks, thats what I thought it looked like on the underside just wasnt so sure on the top side.

[vlad01]

Biggvl mentioned pin offset in the dyno simulator, which I to was also scratching my head over.

Anyway. V6 uses a positive offset of 0.050"

The simulation shows a positive offset hurts power a little while negative increases it.

The trade off is engine noise and piston durability vs power.

here is a pic showing 0 offset and positive offset.

in 0 and -ve offset engines the piston load swaps sides after TDC
in + offset the piston swaps over before TDC where the cylinder pressure is a lot less and also rocks over in a more gentle fashion where the top of the piston is the last to rock over, the rings I would imagine absorb the movement as well.

In the 0 and -ve offset the skirt slaps over in the last movement and I would imagine that to be a bit of a slap. If you look at the pin location in the vertical plane (of our v6 pistons) the speed at which the top or bottom part of the piston rocks over would be a lot faster at the bottom compared to the top, as the pin is like the fulcrum

[Gareth]

Fitting pistons in 'backwards' was a common practice in HQ racing and speedway 202 engines, would alter the timing of the piston, leaves the piston in 'compression' stage for slightly longer - helps produce torque in the low to mid range.

As Vlad said, not good for wear or noise.

[Jayme]

excuse my mspaint skillz, but ive also heard of a bloke boring a 202 at an angle and then decking the block at the same angle to effectively achieve this. apparently it increased torque by a decent margin. the theory was having a more direct push on the crank allowed more power to be transferred for longer during the power stroke or something to that effect.

offset.png (26.08 KiB) Viewed 3938 times

[Gareth]

Nice!!!

[Jayme]

ah found a link with some more info:
http://en.wikipedia.org/wiki/Desaxe

A desaxe engine, is one in which each cylinder is positioned with its exact center (the bore axis) slightly offset from the center line of the crankshaft. "Désaxé", in French, means "unbalanced". Desaxe engines are usually automotive, but the term can also apply to steam engines.
An animation of a Scuderi Split Cycle Engine.

If the offset is in the direction of rotation, it has the effect of increasing the leverage applied to the crankshaft during the "power" stroke, and reducing thrust wasted against the cylinder wall.

In a conventional four-stroke engine, each of the strokes (intake, compression, power, exhaust) involves a nominal rotation of 180°, totaling 720° for the complete 4-stroke combustion cycle. A desaxe engine adds to the duration of the two downward strokes (intake and power), and subtracts the same amount from the two upward strokes (compression and exhaust), with the total remaining 720°. A typical desaxe engine will have strokes of 185° - 175° - 185° - 175°, etc., with the differential roughly (but not directly) proportional to the percentage of offset distance to stroke length.

The relative proportion of offset distance versus stroke length ranges from very small to almost 20%; viz. an engine with an 80 mm stroke may have a cylinder offset of 20 mm.

Use of Desaxe engines is now becoming much more common.[citation needed]. The Volkswagen VR6 & VR5 engines have desaxe cylinders, with an offset of 12.5 mm. The front bank cylinders are offset forward of the crank while the rear are offset rearward. The Toyota Prius has Desaxe cylinder bores offset by 13mm. The new MT-09 motorcycle is the first Yamaha with desaxe pistons.

All single crank split-single engines such as those used by DKW and Puch had, by necessity, highly desaxe cylinders.

The Scuderi engine, as shown in the animated illustration, has highly desaxe cylinders. The compressor (blue) is offset a greater amount than the power cylinder (yellow). Its benefit is to give a better line of thrust from piston to crank though con-rod during downward power stroke but it has disadvantages in vibration and bore wall thrust.

220px-Scuderi_Split_Cycle_Engine_-_Cycle.gif (291.68 KiB) Viewed 3739 times