High compression ratio

[bahy]

Hello guys i'm just new here ,and i want to know it there any possible solutions to avoid the pre-ignition in the high compression engines as the FSAE regs prohibited every thing the cools down the intake ,so i'll be glad to read suggestions
thnx..

[Menisk]

Run E85. If you want to be silly about it, water injection.

[luxsosis]

Or diesel.

[Turns]

You can make sure the intake isn't absorbing too much heat from the head by using an insulater as a gasket (eg phenolic spacer).
You could also try colder spark plugs and lowering your coolant temperature (ie colder thermostat).
Also you can cool it off by adding more fuel by running it richer. This may or may not be better than running it leaner but with less advance.

[KustomizingKid]

I feel like the first question to ask here is have you had a problem with detonation in the first place? What CR are you shooting for that you think you will have detonation problems? With stock cams and 100 octane or E85 I would be very surprised if detonation was a problem... maybe with 93 octane.

Raising the CR of the engine is one project that will be pursued for 2013, and I have been looking into simulations that can answer this question. There are a number of very good papers on this very subject all the way back to the first ones written by Ricardo.

[bahy]

THNX for all people who replied for my question, @KustomizingKid i'm shooting for 13.5 to 14 as we are running NA Honda f4i and we need to squeeze some torque ,regards to the octane we are going to run octane 93 as it's the only available in our country.

[Pete Marsh]

Really?
Raising the compression ratio above the capability of the best fuel you have available is your game plan? And this will achieve what exactly?

Lets just say you can have water injection and whatever else you want that is not allowed by the rules, you would still need to make all that stuff (such that it works), pay for it, and carry it around.

Have you read this thread? - http://fsae.com/eve/forums/a/t...25607348/m/217101453 (http://fsae.com/eve/forums/a/tpc/f/125607348/m/217101453)

Are you secretly working for a rival team perhaps? Or is FSAE just too easy for you and you are looking to add some engine failures into the mix to spice it up a little? If so, there are more exciting engines you can start with that blow up without any help!

Good luck,
Pete

[penna]

as pete said if your running 93 octane fuel, uping the CR to get mid range is probably not the best way to go. If playing with the intake and exhaust doesn't give you good enough mid range maybe try cams as well. This does also have inherent risks, and I would not recommend this unless the rest of you package is already well sorted as there are alot more important things to spend your time on

[JT A.]

Originally posted by bahy:
THNX for all people who replied for my question, @KustomizingKid i'm shooting for 13.5 to 14 as we are running NA Honda f4i and we need to squeeze some torque ,regards to the octane we are going to run octane 93 as it's the only available in our country.

Why do you say you "need" to squeeze more torque?

Have you analyzed your teams' results from past competitions and determined that "not enough torque" is the main problem holding you back from placing higher?

Have you done some kind of track testing or lap time simulation to prove that increasing torque is the most effective way to improve lap time? Effective in terms of time, money, and risk-reward ratio?

Are you sure there aren't simpler ways to improve your performance at competition, such as finishing the car earlier, working on the car's setup, training drivers to drive better, and ensuring that the car is reliable enough to finish all the events?

The biggest challenge in this competition is managing priorities. Many teams have underachieved because they put too much priority on building a super engine. They spend a ridiculous amount of time modifying internals, blowing up motors, & rebuilding them. If your team's performance is lacking in any of the 4 areas I mentioned above (meeting deadlines, finishing events, driver skill, & suspension setup) then I promise you will find more performance improvement by addressing those issues instead of trying to get more torque.

If you want to modify engine internals but don't know how to do it safely, maybe you're asking the wrong question. Instead of asking how to do it, ask yourself why you want to do it in the first place.

[bahy]

Originally posted by JT A.:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by bahy:
THNX for all people who replied for my question, @KustomizingKid i'm shooting for 13.5 to 14 as we are running NA Honda f4i and we need to squeeze some torque ,regards to the octane we are going to run octane 93 as it's the only available in our country.

Why do you say you "need" to squeeze more torque?

Have you analyzed your teams' results from past competitions and determined that "not enough torque" is the main problem holding you back from placing higher?

Have you done some kind of track testing or lap time simulation to prove that increasing torque is the most effective way to improve lap time? Effective in terms of time, money, and risk-reward ratio?

Are you sure there aren't simpler ways to improve your performance at competition, such as finishing the car earlier, working on the car's setup, training drivers to drive better, and ensuring that the car is reliable enough to finish all the events?

The biggest challenge in this competition is managing priorities. Many teams have underachieved because they put too much priority on building a super engine. They spend a ridiculous amount of time modifying internals, blowing up motors, & rebuilding them. If your team's performance is lacking in any of the 4 areas I mentioned above (meeting deadlines, finishing events, driver skill, & suspension setup) then I promise you will find more performance improvement by addressing those issues instead of trying to get more torque.

If you want to modify engine internals but don't know how to do it safely, maybe you're asking the wrong question. Instead of asking how to do it, ask yourself why you want to do it in the first place. </div></BLOCKQUOTE>

Well, first i'm asking why i want to squeeze more torque is just because our budget cannot afford alot of carbon fiber stuff so we have a problem with the weight ,second it's the first time to participate in this competition so we have nothing to work on and do refinements and track testing we have nothing up-till now i'm just thinking forward for another soln ,thnx every body any way.

[RenM]

If this is your first car you should set yourself other priorities then increasing the compression ratio.
Overall its of course finish early and get some testing done.

For your engine, there is a lot more to gain from a well mapped engine then from increasing the cr. Try, if possible, to get an engine dyno running. Next there is tuning the length from intake and exhaust. If you have done that properly you are on a very good way.

[Markus]

Originally posted by bahy:
Well, first i'm asking why i want to squeeze more torque is just because our budget cannot afford alot of carbon fiber stuff so we have a problem with the weight

You can build a car with spaceframe, 13" wheels, and 4cyl engine to less than 200kg without a single carbon fibre part.

I would go as far as stating below 220kg is easy, if you have enough motivated engineering students that respect sound engineering practices.

You only need about 40 horsepower to be fast on endurance with otherwise well thought and tested car. The extra is just to be used to gain tenths of seconds from the laptime.


Originally posted by bahy:
so we have nothing to work on

You should be building the car! As mentioned earlier put your emphasis on car that's ready as early as possible. Especially if you're a first year team.

[KustomizingKid]

We are looking at raising the cr more for fuel economy reasons than power reason... I would also say that you can probably get away with mid 13 number on 93... hell the new 600s are 13.2-13.3 from the factory and at the pump you can only get 91 in a lot of places, really depends on a lot of factors and you need ample dyno time to calibrate and then validate these things.

[Rex Chan]

bahy - did you notice the Monash University car at FSUK and FSG? Finished VERY high in the placings at both comps. Lapped very close to the front of the field in enduro. So, they have a very fast car.

Want to know what engine/weight they run? 40kW and 200kg. FSAE is all about the suspension, and the driver, and very little to do with the engine (and I'm an engine guy).

Monash Motorsport 2011 Dyno torque/power curve (http://www.facebook.com/photo.php?fbid=10150497535163036&set=a.10150495903333036.376035.559588035&type=3)

In short, you're wasting your time.

[bahy]

Originally posted by Rex Chan:
bahy - did you notice the Monash University car at FSUK and FSG? Finished VERY high in the placings at both comps. Lapped very close to the front of the field in enduro. So, they have a very fast car.

Want to know what engine/weight they run? 40kW and 200kg. FSAE is all about the suspension, and the driver, and very little to do with the engine (and I'm an engine guy).

Monash Motorsport 2011 Dyno torque/power curve (http://www.facebook.com/photo.php?fbid=10150497535163036&set=a.10150495903333036.376035.559588035&type=3)

In short, you're wasting your time.

Yes bro,we've decided no to go mad with the CR ,thnx for ur advice http://fsae.com/groupee_common/emoticons/icon_smile.gif