5EXi-R Max Power

Jon@JNRacing.co.uk · #1 7th March 2007, 09:13

Hi all,

As our car the car is away at the moment and I have some time, ive been thinking and come up with a little plan to make our exi go quicker, just need a little bit of help so I dont kill myself.

What is the most power that has been put through an exi chassis at present, every time i ask mark at marlin about this he wants to now what i am planning on doing, and i dont want to tell him.

Ive been told what power I can get out of the engine with some work but im not sure if the car will take it, in fact i doubt the car will take it.

Regards Jon

limpabit · #2 7th March 2007, 09:40

I think John (marlinturbo) is looking at 300-400 BHP with the Rover turbo. There was some chassis strengthening at th rear I think to help handle the power. Marlin at some point offered the strengtheners to increase stiffness.

Jon@JNRacing.co.uk · #3 7th March 2007, 10:09

May need a few of them then, and a lot on top, have to see what can be done when we do it, Cheers

alackofspeed · #4 7th March 2007, 12:26

I think, though might be wrong, that John's car is one of the earlier ones, and the stregthening on his is present on the later chassis. Also I believe his is box section, rather than tube.

I have a suspicion the chassis might be found wanting with 200bhp..... and I suspect how much power the car can take depends totally on how much time and effort you're prepared to put into stregthening the chassis. However theoretically it'll be a law of deminishing returns, cos although you can easily add material to increase the power handling of the chassis, you'll lose some of the braking / direction changing ability owing to the extra mass.

Incidentally, that's a curious choice of thread title, cos it smacks of jazzed up hatchbacks that have been coated in glue and crashed into Ripspeed!

Jon@JNRacing.co.uk · #5 7th March 2007, 13:08

By the sounds of things I think a bit of chassis development work will need to be done. With the grip that we will have on the rear Mark has shown concern about the suspension arms taking the force. Somthing that will take a bit more than just tuning an engine to get this idea to work.

Thanks for the help guys,

p.s. if your wondering what power im hoping to put into the chassis, its around the 500bhp,

craig · #6 7th March 2007, 16:35

Jon, I posted a thread ages ago but can't seem to find it, seems to have gone about the chassis, but basically mine was looked at ages ago by some rod builders of a friend in my street and they laughed when i said I was thinking about putting 300bhp through it...........can't remember everything they said but do recall them telling me that 300bhp would twist chassis if booted

Jon@JNRacing.co.uk · #7 7th March 2007, 16:42

thanks Craig thats what im worried about, ive been told by a company they can get 450-500 bhp out the engine with 350 lbs ft of torque, which is going to twist the chassis badly, as the tyres will grip and go, think i may need to get marlin to make up a new chassis, and then transfer all the kit from our current car onto it, i now that the suspension will take it and the brakes will take it, just the chassis and sus arms, I dont fancy dieing before im 21, so some long calculations needed i think.

Jon

grant620 · #8 7th March 2007, 23:53

You can see the chassis bend with only 250lbft!
I mean - visibly, from teh side of the road - the thing bends as you welly it!

Jon@JNRacing.co.uk · #9 8th March 2007, 08:43

Quote:

Originally Posted by grant620

You can see the chassis bend with only 250lbft!
I mean - visibly, from teh side of the road - the thing bends as you welly it!

If you can see it bending, how can john have 270lbft if not 300lbft in his car without damaging anything and still be able to drive it if it bends so much??

alackofspeed · #10 8th March 2007, 12:00

I assumed mine would do some undesireable things if too much power is put through it, which leads me to ask:

If John is leading the 'power in a marlin' race, what is he doing to remedy the shortcomings he's encountering?

I've been giving some thought to addressing what I see as weaknesses, but until I have my bodywork, I won't know what I can do within the dimensional constraints.

Jon@JNRacing.co.uk · #11 8th March 2007, 12:13

Id like to now as well, but ive been told that there is an easy way, not the cheapest but one that will work best. Re-design the chassis so it can take more power and build a new one, the problem with just playing at the back on the car were the engine is, is that everything else starts being pushed past the boundries. which is more important power or your life??

craig · #12 8th March 2007, 12:55

Jon is right imo regards building a new chassis as the gauge of steel used is just not big enough, when you look at the likes of the cobra's and the atom supercharged it's about 2" all round not just the engine bay

alackofspeed · #13 8th March 2007, 14:36

Forward of the bay, is what I’ve been thinking most about. A company local to me (http://www.jandttubes.com/), made the prototype roll cage / screen support, and the chap has taken a keen interest in what I’ve been up to. Once I’ve got the bodywork, and know where space is available, I’ve been thinking for a while I’ll look at supplementing the existing structure with some sturdy tubular section steel. To a point appearance isn’t that important to me, but I know I’ll be very miffed if I find the performance is heavily compromised by a spaghetti chassis.

Jon@JNRacing.co.uk · #14 8th March 2007, 16:58

Spoken to a 'a person' who shell remain nameless, that has told me the road chassis is a lot weaker than our race one. The area's were the chassis needs to be modified is forward of the rear bulkhead, or you can fit surport arms to connect the chassis and roll cage, like the race cars have.

alackofspeed · #15 8th March 2007, 17:39

From what I've seen of the race cars, there are a number of subtle diffeences, some of which address aspects of the chassis I look at and "errrmm" a lot at. This in part is why I didn't opt for a car with doors - i didn't like the concept of removing depth from the side of the car, lowering the second moment of area, and the consequential reduction in stiffness.

From the start I questioned the "tub" to rear bulkhead interface, and the main longitudinal box sections running from the tub. I've thought for a while about adding something approximating a side impact bar, not for safety's sake (I figure striking / being striked by another vehicle is going to be nasty no matter what!), but to try and extract more benefit from the roll hoop.

I'm not bothered by the failings (in my view) of the chassis, as part of the fun of this project is problem solving.

The side impact bar (if you like) of your car, how is that attached to the rest of the roll hoop? I'm presuming it's removable to enable the standard aspect of the cage to be fitted around the chassis.

Jon@JNRacing.co.uk · #16 9th March 2007, 08:14

The side impact bar which we have to have to be able to race, is bolted onto the rollcage, alone with the rear surport arms that connect the cage to the engine bay. Well i was talking to this person yesturday, he said that the weakest part of the car is the between the front and rear bulkheads, this is the area that I have a race car can address easyer than most, as I dont have a second seat to worry about.

MikeR · #17 9th March 2007, 11:30

I've been following this thread and am getting worried that the first pothole i hit with the car the chassis will fold in half as i've gone for the doored version. Please can someone reassure me that i've not bought a pile of @%$ that's not properly designed.

Regards
Mike R

Jon@JNRacing.co.uk · #18 9th March 2007, 11:48

Mike at present I have not yet seen a twisted or broken chassis, only exi ive seen broken in any way was Marks race car when he went in to the tyre wall at donnington at 80mph, but the chassis was ok,

The 5EXi-R demo car has more power than what you will have and has doors, which has taken a hammering on and off the road and that has been fine.

Mike when you have a look at ours you will see why I am a little concerned about the max power the chassis will take. I have plans that Mark at Marlin isn't too keen on to say the least.

Jon

alackofspeed · #19 9th March 2007, 12:10

Jon, do you have any pictures that show the side impact bar in more detail?

Jon@JNRacing.co.uk · #20 9th March 2007, 12:20

Below are a few links to photos on my site, they are too large to upload and i haven't got time at present to resize them, hope this helps, I can send them to tonight if you like a larger version. Jon

http://www.bebo.com/PhotoAlbumBig.js...oId=2208431937

http://www.bebo.com/PhotoAlbumBig.js...oId=2889538490

http://www.bebo.com/PhotoAlbumBig.js...oId=2889539823

http://www.bebo.com/PhotoAlbumBig.js...oId=2889946990

http://www.bebo.com/PhotoAlbumBig.js...oId=3669476132