Hypothetical; front/rear weight ratio and HP goals

[Hasbro]

Wasn't sure where to put this. Woke up in the middle of the night and started running numbers through my head(damn late night snack!). If the front /rear weight ratio of 66/34 were changed to about 60/40, what would the result be? I realize this is a very complicated question, especially for the M100's suspension design. But if the car were, for instance, lightened to 2,000 lbs. and 100 lbs were added towards the rear with an undertray... opinions?

[Dico]

PaulP's weight distribution varies dramaticaly depending on wether or not he's had lunch.

Hasbro, lay off the cheese before bedtime

[Hasbro]

No cheese was involved but chocolate is definitely suspect.

What I'm getting at is M100 specific.

By reducing/transferring the weight and moving it closer to the roll center it will improve adhesion by allowing all tires to work at their highest efficiency, reduce understeer, improve braking, yada yada.

I've had lots of high performance front wheel drive cars and all of them responded well to lightening the front. What I wonder is that with the M100's unusual and finitely tuned suspension(of which I haven't researched and don't understand well yet) will the car respond to weight transfer any differently from other modified fwd cars?

[Elanlover]

I'm not sure you'd "have" to add weight to the back if you were removing from the front. Simply removing from the front would shift the % in favour of a 60/40 split. Have to take a fair bit off though.

Where are you planning to subtract from? I'm all ears!

[Hasbro]

I'm not sure you'd "have" to add weight to the back if you were removing from the front. Simply removing from the front would shift the % in favour of a 60/40 split. Have to take a fair bit off though.
Where are you planning to subtract from? I'm all ears!

Well, I suppose just pulling off the front weight would be simpler and would also help retain the definition of the M100. Going for maximum weight reduction really isn't what this car is for or it would have been done by the performance purists many moons ago. It would also be pretty hard just lightening the front as some improvements would lighten the rear also, such as 25 lbs just from the rear wheels. And a lot of removable weight is in the middle. That's why I mentioned additional rear undertray area weight.
With a "normal" fwd this would be advantageous but when I read about the M100's front suspension I just get confused! If there is a good article around that explains it in layman's terms that would be a big help.
By the way, where does the extra 60 or so lbs. come from on the US car? And where does the 115 lbs come from on the turbo vs. the NA?
By the way, a stock US car with driver and 1/2 tank of gas has a power to weight ratio of 18.5 lbs to 1whp! Another HUGE reason to pull weight.

[Elanlover]

The extra weight on the fed model likely comes from the crash zone up front (the Fed model is longer than the UK model), airbg stuff and precat perhaps.

I don't think too many people have tried to take weight out of the front of the car specifically. We're really talking about the engine bay and I can't think of where you'd get a big hit in weight reduction from modifications. Changing the front brakes and rotors out can save weight but probably only 20 lbs total perhaps? I never checked after Brian's Wilwood upgrade was installed - someone likely knows what the savings were. Swapping the precat for something hollow and lighter could save another 10 perhaps?

But, I don't know where you could find gains of, say 200lbs in the front without major customization of parts in lighter materials. Cost is what probably has stopped people from exploring that I would think. Changing wheels saves but its all around as you stated (seats too perhaps) and I think lightening the front a bit would be the best route to go. I'm not sure how keen folks would be to scrounge around to save some weight in th front only to put it back in the rear of the car. I'd keep every pound off the car I could

I know there's folks here smarter than I on an issue like this though.

[Hasbro]

FYI, it's obvious I'm not an engineer, just a weight/performance fanatic. I'm doing this to set an initial goal and develop a plan to achieve that goal. Any feedback is appreciated.

Long story very short, after playing with numbers probably the best advantage towards reducing the front verses the back would be around 50-75 lbs., depending on how far one is willing to go. This equates to about a 1% change in the ratio at best. The addition of 100 lbs. of lower rear weight would add about 2% more. From 66f/34r to 63/37. Not worth it but a fun exercise. Reducing the Federal car's junk would help even more as it is 67/33 stock. My guesstimation is that 150-200lbs total removal before add-ons and "Fed removal"would work well without changing the integrity of what is an M100.

The next steps with regard to above would be corner weighing with adj. coilovers and aero work.

My personal goal for a street car has always been to have between 14-8 lbs. to 1/whp. including driver ,depending on the car. 10-12 sounds about right for the Elan. About a 50% increase. Lots of thrills without sacrificing dependability. So I figure around 200-240 whp. with 200-210 whp being a good initial goal (about 20-25 extra whp would be required at stock Fed weight). Any suggestions as to how to best approach this? I imagine the Everest chip is the first step but would the next steps be? I will have to do this in stages.
1. chip, 170+ whp
2. exhaust?, 185+?

[surfboardfiller]

Leave the car alone and spend the time on your driving techniques

If you have a problem with understeer take it to a mechanic, it's probably the tyres.

[Hasbro]

Well, you are God and I should listen to what you say.
















There's always the confessional.

[Specky]

have you dun a four point weigh of the car to see how it's weight is disributed?

TTFN

[Hasbro]

^That would definitely be the next step.

Does anyone have any feedback re. the steps towards building a 200+ whp motor? 225-240 absolute max. According to a rolling Dyno-Jet.
I saw some info on the old LEC page but most of it was not available. Has anyone done an updated version or can someone refer me to someone that can enlighten me? I think my goals are in between an Everest chip/exhaust and LGM's beautiful project.
Thanks for everyone's patience. I'm learning.

[surfboardfiller]

^That would definitely be the next step.

Does anyone have any feedback re. the steps towards building a 200+ whp motor? 225-240 absolute max. According to a rolling Dyno-Jet.
I saw some info on the old LEC page but most of it was not available. Has anyone done an updated version or can someone refer me to someone that can enlighten me? I think my goals are in between an Everest chip/exhaust and LGM's beautiful project.
Thanks for everyone's patience. I'm learning.

You could loose a lot of weight from the car to increase performance and handling, I think LGM has changed the fly wheel - a good place to start and better than putting a sandbag in the boot

The Everest chip is good, but the one I have is really only making the best of what the old turbo can offer. I think you could gain a lot more performance by replacing the turbo, you could look into variable vein turbo and 2 stage turbos and supercharging If you loose the lag the performance will increase without over pressurising the head, and you don't even need to take the engine apart!

Honestly, you can understeer, oversteer and 4 wheel drift these cars they are so well ballanced!

[DeeAitch]

Honestly, you can understeer, oversteer and 4 wheel drift these cars they are so well ballanced!

Have a look at lift off oversteer, trail braking etc - track use only tho'

On my one and only track day I checked the tyres after a lot of my best laps - all 4 corners were equally scrubbed up - melted would be a better description - across the whole tread width - indicating they were all being worked pretty much the same. I was very surprised, expecting the rears to have much less signs of stress!
For me, moving the weight bias to the rear would give you traction issues - weight transfer and all that. Far better to lose overall weight and keep the bias as is, but I'm no expert so get your guns out!
Another 50 HP would be nice but I fear it involves more boost = new Turbo / bigger injectors, head gasket, remapped fueling, big exhaust, LSD, not to mention better brakes etc etc = project creep

[Elanlover]

Does anyone have any feedback re. the steps towards building a 200+ whp motor? 225-240 absolute max. According to a rolling Dyno-Jet.

This is easily acheivable. I'm estimating that I'm getting about 205- 210 right now at the flywheel (not sure what that translates to at the wheels). All I've done is replace the exhaust with a freer flowing, larger bore system, new air intake and Alan's chip. I've yet to replace the pre-cat but that's a project for this winter and should net me another 5 - 7bhp I think. Costa has hit over 400 with NOS. There's plenty of stuff on attaining the power you've described in this forum. Just start searching

[surfboardfiller]

For me, moving the weight bias to the rear would give you traction issues - weight transfer and all that. Far better to lose overall weight and keep the bias as is....

Oh yes! The Elise/Caterham 7 etc have less BHP are quicker because they are lighter.

Another 50 HP would be nice but I fear it involves more boost = new Turbo / bigger injectors, head gasket, remapped fueling, big exhaust, LSD, not to mention better brakes etc etc = project creep

The Turbo gives power and increases the internal pressure of the engine. If you increase the Turbo/pressure too much you can damage the engine. The Isuzu Turbo only provides a boost at a limited rev range and has a 'lag'.
I'm proposing a system to increase the pressure outside that range, so you have the same pressure but for more of the rev range. That way the boost starts earlier and causes less lag, but the pressure is limited to 0.9 Bar so you should be all right with the existing head gasket. Does that make any sense?

[DeeAitch]

Maybe I've read this wrong but Hasbro talks about whp = Wheel Horse Power?
If so - assuming around 20% transmission loss - he is looking for circa 280 at the crank IMHO not possible with 0.9 bar boost.

[surfboardfiller]

Maybe I've read this wrong but Hasbro talks about whp = Wheel Horse Power?
Is so - assuming around 20% transmission loss - he is looking for circa 280 at the crank IMHO not possible with 0.9 bar boost.

I would not assume anything. 280 bhp is possible, it has been done. It is going to be very expensive.

I'm talking about overall performance, surely that's the goal, not a figure. I'm questioning the point of a narrow high power band which is what a large turbo will give you and leave you with more lag and the huge job of sorting out the head clutch and everything else to handle the torque. What's the point if it gives you 280 bhp one second and 120 the next? I'm offering an intelligent solution to increase power throughout the rev range and saying you don't have to increase the pressure >.9 to do that The factory pressure of these engines is about .6 bar full boost delivering 165 bhp.

In short, huge figures look good on paper but don't necessarily make your car quicker from 0-60.

[Hasbro]

Actually I was thinking 230-240 bhp. (for me, bhp is meaningless, it's all about the hp/weight ratio) A lot of guessing right now as I haven't seen much hard evidence (dyno)on here. And the figures are merely a tool for developing the motor. I'm not trying to turn it into a monster that constantly is on the blocks. Been there. This queery is to determine a practical goal and then do it. Make up a shopping list and incrementally finish the list. I think the goal will be somewhere between an Everest/exhaust and some of the serious cars like DavidM, Lgm, etc. Probably similar to several cars here .
Also, one of the main reasons for pulling weight is the "free" hp and less stress on the motor. A 10% increase in hp by reducing the weight by 10% if you will.
Appreciate all of this input.

[Elanlover]

If you're looking for 230 bhp (understand the point about power to weight) then I believe you can get close to that relatively cheaply. I think someone's suggested going beyond those numbers is where it gets really expensive. That's when you need to start swapping out the turbo, injectors, etc.

But, if you install Alan's Elysium chip, a freer flowing exhaust, dump the pre-cat and get a freer flowing intake you're going to get close just by doing that. You'll find a big difference in performance from these (relatively) cheap and easy upgrades. Of course, you'll need to do something about the brakes too...............

Phil's got a good point about the power curve. Its all above 4,000 rpm - exactly what you'd expect in a small 4 banger. Its hard to squeeze more power out of the low end of the curve without some "creative" upgrading

[Hasbro]

Elanlover, to you I bequeath my firstborn(just in time for college bills).
I appreciated Phil's comments but didn't want to respond until things were headed in the right direction(in other words, I made my intent a little more clear).
My weakest area of auto knowledge is electrics and turbos. I imagine to get more lower and higher end performance that Phil is suggesting would include a programmable brain, custom cams, air/fuel sensor, modern turbo and properly flowed intake, head, and exhaust? $$$$$ Is that where you are going, Phil?