The Technical Questions Thread

[NSXType-R]

Originally Posted by Rasmus

I assume you mean the STS kits. Same as other turbos; piping, and lots of it.

Here's a TT kit for the C6:
http://www.jlturbo.com/pictures/sts/...-sts-turbo.jpg

And a 4th gen Camaro:
http://i177.photobucket.com/albums/w...maro-pipes.jpg

And just to be ridiculous, here's the TT Mustang GT kit:
http://www.mustangv8.com/en2/uploads...517c49e78f.jpg

Yes, these thanks.

Originally Posted by fpv_gtho

Lag, lag, lag, lag, lag and lag. First theres all that piping to the back of the car, then its got to go all the way back. Must do miracles for throttle response.

Lag doesn't seem to be much of an issue. Jay Leno had one of those turbo Vettes on his videos and they seem to do fine.

Originally Posted by clutch-monkey

what's the point then? no space in the engine bay?

I think that was it.

[Matra et Alpine]

Originally Posted by hightower99

Really so your opinion is that it is impossible to cool the rear cylinder pair of a flat 4 boxer engine in a bike without increasing the radiator size by a huge amount and because the water routing would be too complex (meaning space consuming right?). What calculations did you base that off of?

EXPERIENCE.
SOmetimes yuour math book knowledge isn't enough.
Go read up on the squariel and Suzuki "kettle" engines which always had problems with the two rear cylinders overheating ... hence the nickname "kettle"
"complex" by managing to control the cooling such that the rear and front cylinders operate at teh same temperatures. That was clearly obvious. It is plain and simple ENGINEERING that whilst the math can be calculated the prcatical implementation has little success.

Sorry this "obvious" insurmountable issue is not apparent to me...

THAT it is clear.
However, it's not an issue with the issue or with me ... it's your lack of real world knowledge ADN as I'd pointed out gently before bikes are different to cars.

Odd that you quote the obvious and then add the insurmountable What do YOU mean by insurmountable. You can achieve it for sure ... but NOW try and sketch it so that you get good exhaust gas flow, keep the exhauts routing WELL away from the inlet and fuel ( don't want warm mix entering engine ), find space to ahve an effective air flow through a large radiator, keep good ground clearance, keep narrow frontal area, keep heat away from rider and finally make the rider able to lean the bike at least 55 degrees from vertical and with the addition of knee slider for balance control even further. The math is simple to show how narrow the bodyshape must be up to the wheel centres PLEASE, draw two wheels in front and side elevation and sketch out where you try to put all the parts. Sersiouly, it's clearly a better education than anyone trying to tell you the facts.

[hightower99]

Originally Posted by Matra et Alpine

EXPERIENCE.
SOmetimes yuour math book knowledge isn't enough.
Go read up on the squariel and Suzuki "kettle" engines which always had problems with the two rear cylinders overheating ... hence the nickname "kettle"

I believe you are talking about the Ariel Square Four and the Suzuki RG500 right? I think I have heard of the Suzuki GT750 being called the kettle but it was an I3 engine (no "rear" cylinders). If indeed they had problems with keeping the rear cylinders cool I would think that for the Ariel Square Four it had to do with the fact that it was air-cooled and that it had all 4 cylinders placed directly beside each other which would lead to significantly greater heat soak to the rear cylinders then a flat 4 would have, and for the RG500 well it is a two-stroke engine (as is the Ariel S.F. BTW), and again it uses the odd square engine arrangement that placed all the cylinders tightly together. It was water-cooled and from the pictures I found it certainly didn't have a huge radiator compared to other bikes of that period. A 4-stroke flat 4 would simply suffer much less heat soak to the rear cylinders.

Originally Posted by Matra

"complex" by managing to control the cooling such that the rear and front cylinders operate at teh same temperatures. That was clearly obvious. It is plain and simple ENGINEERING that whilst the math can be calculated the prcatical implementation has little success.

I didn't say it was going to be easy you could either run the coolant through the engine by entering through the rear cylinders and exiting from the front cylinders or you could make a parallel circuit with two thermostats to control the temperature of each side of the engine (maintaining the same temp on both sides).

Originally Posted by Matra

but NOW try and sketch it so that you get good exhaust gas flow, keep the exhauts routing WELL away from the inlet and fuel ( don't want warm mix entering engine ), find space to ahve an effective air flow through a large radiator, keep good ground clearance, keep narrow frontal area, keep heat away from rider and finally make the rider able to lean the bike at least 55 degrees from vertical and with the addition of knee slider for balance control even further. The math is simple to show how narrow the bodyshape must be up to the wheel centres PLEASE, draw two wheels in front and side elevation and sketch out where you try to put all the parts. Sersiouly, it's clearly a better education than anyone trying to tell you the facts.

Maybe you should just show me a drawing like that showing me why it wouldn't work

Its odd that you say that it is possible to do but then go on to ask me to prove it? I have done some doodling and as far as i can see there should be plenty of room...

I don't know why you can't see it

[Matra et Alpine]

^^^^ Because I know PRACTIAL about bikes.
Post the doodles.
Don't see why I should draw what are YOUR ideas to show the obvious problems.

2 thermostats and one radiator ? You're kidding yes ? That woudl be fine on a huge engine with a large radiator and volume of water. Just not gonna happen and operate corectly when differeing thermostats open/close. Love to know how you stop these pipes getting heat soak pickup. See bikes have NO spare space for lading things back and forward multiple times. It's wasted weight, space and control problems

[hightower99]

Originally Posted by Matra et Alpine

2 thermostats and one radiator ? You're kidding yes ? That woudl be fine on a huge engine with a large radiator and volume of water. Just not gonna happen and operate corectly when differeing thermostats open/close. Love to know how you stop these pipes getting heat soak pickup. See bikes have NO spare space for lading things back and forward multiple times. It's wasted weight, space and control problems

One main radiator body that incorperate two radiators... Basically instead of one large radiator cooling the whole engine two smaller ones cool one side each.

isn't too complicated

[Matra et Alpine]

For the non-engineering. If you dont' have enough mass of water flowing then you will get hotspots. So you can't HALF the radiator. Dependant on piping you coudl even seee that you need to keeep the SAME size.
Do you know any fluid thermodynamics ? Done any heat CFD sims ?
HP R&D for 10 years .... the largest effort in the last half of a project was always trying to get the cooling right I always chuckle when folks dismiss it as not complicated or easy

[hightower99]

Originally Posted by Matra et Alpine

For the non-engineering. If you dont' have enough mass of water flowing then you will get hotspots. So you can't HALF the radiator.

Ah but as I said half the radiator will only be responsible for cooling half the engine, the engine itself will see the same mass flow as if it was being cooled by one, larger, radiator.

Originally Posted by Matra

Do you know any fluid thermodynamics ? Done any heat CFD sims ?

By fluid thermodynamics if you mean things like convection and the component advection and diffusion then yes I have learned and I continue to learn about that in school. Unfortunately I haven't had the chance to do any CFD where heat was taken into consideration (only stuff I have been a part of so far is focused on pressure and density)

I never said that making the cooling system would be easy I am simply rejecting the notion that creating a good cooling system (i.e one that properly cools the engine without taking up too much room) is too difficult to do for the trained professionals.

[Matra et Alpine]

ht, you missed COPMLETELY my point about mass of the water cooling and jaust because it's cooling only half the engine does NOT mean it only does half the work.
THat's true as I'd said already IF you have big rads and large mass of coolant.

Well it IS too difficult to do for the trained professionsals .... THAT is why tou don't have the engine configuration you are suggesting ( amongst other reasons ) and WHY if you look at a race v road bike you will see LOTS of additional vents, paths amd bodywork to increase the cooling from "stock".

The problem iwth heat trasnfer is it's not like pressure. A hot spot can then self-fuel (!) the increase of tempareature in that spot. It's NOT pure math .. it does NEED modelling.
Hope you get the chance to do some and then will understand better the diffrences and impact.

For example, switching flow on/off was the "old" way of managing heat transfer for cooling. But this can't avoid hot spots being created and the control system fluctuating.
Modern methods aim for constant flow and then modulate the temperature of the fluid/air. SO more and more "performance mods" to cars is the replacement of the mechanical pump ( which altered speed with RPMs ) with electronic high flow pumps which maintain a consistent flow rate.
Easy to do in a large cooling plant ... nightmare to try to achieve in a small space like a bike

[drakkie]

I'd like some more info on the pushbelt alternatives. So the LUK chain and the Aichi belt. Does anyone have any ? I'm specifically interested in the losses of the system compared to the Bosch-VDT pushbelt. Last two weeks I have had a good 4-5 hours of presentations by various companies; but offcourse they promote their own product.

What I forgot to ask to the technical director of VDT, was why they limited the size of their pushbelt to 30mm and 24mm versions. Is it not possible to make them bigger for strength reasons ? They did tell me that they kept two for simplicity purposes in production. But since they want to handle all vehicles (diesel vehicles too, which are problematic on torque amounts) and do a lot of development work on it, why not make them larger and use say 12 strings instead of 7 on the 30mm belt ?

[Kitdy]

What are the advantages and disadvantages of Jaguar's aluminum monocoque chassis?

[LeonOfTheDead]

Originally Posted by Kitdy

What are the advantages and disadvantages of Jaguar's aluminum monocoque chassis?

it's light, it's difficult to repair in small accident, it's a bit larger than a steel monocoque but it's stiffer, and is sexier if not painted.

[Ferrer]

Originally Posted by LeonOfTheDead

it's light, it's difficult to repair in small accident, it's a bit larger than a steel monocoque but it's stiffer, and is sexier if not painted.

No, it isn't.

[LeonOfTheDead]

Originally Posted by Ferrer

No, it isn't.

ok, it's sexier with a soft light.
Damn, even the worst prostitute can bug you with the right light.

[Matra et Alpine]

drakkie, I'm guessing that the cost of setting up automatic manufacturing lines for the belts is quite high especially given the metals and construction.
I did find this interesting where long time back they were seeing MATERIALS was the way to make improvements. http://www.bosch.nl/content/language...elt_design.pdf presume this was the belt design you woudl ahve seen ?
I guess they've fdetermined optimal belt sizes. First to not have too muchben on the smallest gear to reduce stresses but also not to long a straight section between the wheels otherwise you're gonna risk getting harmonic vibrations ?
All guesses I'm afrad D

[drakkie]

Originally Posted by Matra et Alpine

All guesses I'm afrad D

Thanks! It's a pretty interesting document, i'll take my time to read it tomorrow. It's a bit odd the exact material is quoted in the document, whilst their engineers (of which i met half a dozen over the years) never are able to tell us, because of company secrecy policy

This was both when I visited their plant and had a 4-hour technical story from an engineer and at various congresses, meetings, promotion days and whatever not. Even odder are to find the names of two persons that denied it before above this document!