Project Build - Elise GT: Honda Swap / Widebody Conversion

[KingK_series]

Loving your work Ken, keep it up

are you not adding massive amount of weight?

did you weigh the engine box before you installed?? -

I take from Ken's previous posts that he is not entirely focused on pure performance, and part of his motivation comes from aesthetic aspirations.

OK , novel, but chaque un a son gout.... I suppose.

[MacLotus]

Thanks for the comments gentlemen! Yes, undoubtedly more fiberglass adds more weight. I did weigh the car beforehand (1742lbs) and will post numbers afterward. I would also note I removed many interior components as well. Those Tillett CF seats are really lite, and I ditched the fire suppression and roll bar cross brace (petty bar) in the Sport 190. New wheels and tires are lighter too.

If I had to guess, I'd estimate each clam gained maybe 30-40lbs. But I gained 40-50% more rubber on the ground as a result of the modifications. Many racers have indicated the additional weight will help a bit with the wider tires (weight per square inch of tire patch). As for power overcoming additional weight, a new supercharger is in the works. It should deliver 400+ whp. It will be both charge cooled and meth injected, and will get a set of dog gears to handle the 300+ lb/ft torque the SCK24 will produce.

Lastly, the new body is significantly better aerodynamically than the OE Elise, which is REALLY bad. As for molds, no plans in the works.

[KingK_series]

Thanks for the comments gentlemen! Yes, undoubtedly more fiberglass adds more weight. I did weigh the car beforehand (1742lbs) and will post numbers afterward. I would also note I removed many interior components as well. Those Tillett CF seats are really lite, and I ditched the fire suppression and roll bar cross brace (petty bar) in the Sport 190. New wheels and tires are lighter too.

If I had to guess, I'd estimate each clam gained maybe 30-40lbs. But I gained 40-50% more rubber on the ground as a result of the modifications. Many racers have indicated the additional weight will help a bit with the wider tires (weight per square inch of tire patch). As for power overcoming additional weight, a new supercharger is in the works. It should deliver 400+ whp. It will be both charge cooled and meth injected, and will get a set of dog gears to handle the 300+ lb/ft torque the SCK24 will produce.

Lastly, the new body is significantly better aerodynamically than the OE Elise, which is REALLY bad. As for molds, no plans in the works.

Hi

yes but surely the issue is balance.

To my mind the most important issue in a car is balance [except perhaps in a dragster?}- so are you not putting a lot more weight over the rear?

[MacLotus]

Balance when weighed was 49.5%F/50.5%F. Weight has been evenly distributed around the car. In fact, an Exige rear clam has a third more glass, so the argument found be made that throws balance off. Then add a wing... How much does that add in weight and downforce. Truth is, an Elise has TERRIBLE rear lift to an inherent poor aerodynamic design in the rear. Uncorrected, additional weight helps. I think your balance argument as an 'issue' specific to my redesign is not fully thought through. Just MHO. Cheers!

[roadboy]

Balance when weighed was 49.5%F/50.5%F.

So you've shifted the weight balance forward considerably over the standard setup then?

Dan

[KingK_series]

Balance when weighed was 49.5%F/50.5%F. Weight has been evenly distributed around the car. In fact, an Exige rear clam has a third more glass, so the argument found be made that throws balance off. Then add a wing... How much does that add in weight and downforce. Truth is, an Elise has TERRIBLE rear lift to an inherent poor aerodynamic design in the rear. Uncorrected, additional weight helps. I think your balance argument as an 'issue' specific to my redesign is not fully thought through. Just MHO. Cheers!

not sure about that

most Elises are 61/49 in stockish form which is way too much on the rear - which is why anyone sensible would want to lose rear weight bias, - ie not go anywhere near a Honda!

[MacLotus]

61/49? That's 110. I've had my Honda-based Elise corner balanced by the same race shop three times. It was never that far out of wack. It's nearly perfect balance... were the comments from my alignment guy.

[MacLotus]

I just pulled the numbers... Cross balance LR/RF - 904lbs - 49.7% - Total wet weight - 1819lbs with driver

Front to rear is 46/54 (w/o driver), but my Elise was the lightened Sport190... a little different from OE.

[KingK_series]

61/49? That's 110. I've had my Honda-based Elise corner balanced by the same race shop three times. It was never that far out of wack. It's nearly perfect balance... were the comments from my alignment guy.

I beg your pardon my mistake

here's an old list of k engined cars

[KingK_series]

I just pulled the numbers... Cross balance LR/RF - 904lbs - 49.7% - Total wet weight - 1819lbs with driver

Front to rear is 46/54 (w/o driver), but my Elise was the lightened Sport190... a little different from OE.

how much does the car weigh with no driver?

all the weights in the sheet are with no driver but some fuel.

very little weight to be saved from the front end - bar battery, so very curious....?

Properly designed car should be 55/45.

[KingK_series]

Balance when weighed was 49.5%F/50.5%F. Weight has been evenly distributed around the car. In fact, an Exige rear clam has a third more glass, so the argument found be made that throws balance off. Then add a wing... How much does that add in weight and downforce. Truth is, an Elise has TERRIBLE rear lift to an inherent poor aerodynamic design in the rear. Uncorrected, additional weight helps. I think your balance argument as an 'issue' specific to my redesign is not fully thought through. Just MHO. Cheers!

I always thought the Elise was worse for front lift........?

you realise your widebody will significantly increase frontal area and therefore drag?

[MacLotus]

I just pulled the numbers... Cross balance LR/RF - 904lbs - 49.7% - Total wet weight - 1819lbs with driver

Front to rear is 46/54 (w/o driver), but my Elise was the lightened Sport190... a little different from OE.

how much does the car weigh with no driver?

all the weights in the sheet are with no driver but some fuel.

very little weight to be saved from the front end - bar battery, so very curious....?

Properly designed car should be 55/45.

I'm assuming when you say 55/45, you mean 45% of the cars weight is on the front wheels, and 55% is on the rear. Measured that way, I'm 46%F/54%R. Balance is not simply measured F/R. Balance (or corner balance) is measured typically LR to RF. Mine is 1742lbs, 49.7 cross balanced.

All this aside, you assumed my body changes added significant weight to the rear only. That is inaccurate, so balance is moot until the new corner balance numbers are in. In fact, if I had to wager, I'd guess the front clam received more weight than the rear.

As for drag, any aerodynamic modification (e.g. Wing, splitter, etc) will cause additional drag. The key is if it is done to effect change on a cars performance. You appear to believe the Elise was designed aerodynamically for the track at high speed. In fact, it was not. The Elise has a front end that funnels air under the car vs. around the car. That increased pressure under the car manifests in rear lift (the reason Lotus added a spoiler to the Elise design). The Exige actually requires a wing to compensate. It's not for looks. Engineers also added front aero to compensate for aero inefficiencies of the Elise design.

Bottom line, the Elise is a street/production car designed for sub-80mph aero performance. Get it to 135mph and it's freaking SCARY. It wants to get airborne. The front end has been redesigned to move air around/over the car and not under the car. It's similar to the GT1 front end, or Porsche GT1 front ends. Additional drag, yes. Additional front aero performance... 100% better. 400+ whp will compensate for that drag, creating better airflow at 150mph. American race tracks have up to one mile straights. Want good track times, you better make use of high speed.

[KingK_series]

I'm assuming when you say 55/45, you mean 45% of the cars weight is on the front wheels, and 55% is on the rear. Measured that way, I'm 46%F/54%R. Balance is not simply measured F/R. Balance (or corner balance) is measured typically LR to RF. Mine is 1742lbs, 49.7 cross balanced.

All this aside, you assumed my body changes added significant weight to the rear only. That is inaccurate, so balance is moot until the new corner balance numbers are in. In fact, if I had to wager, I'd guess the front clam received more weight than the rear.

As for drag, any aerodynamic modification (e.g. Wing, splitter, etc) will cause additional drag. The key is if it is done to effect change on a cars performance. You appear to believe the Elise was designed aerodynamically for the track at high speed. In fact, it was not. The Elise has a front end that funnels air under the car vs. around the car. That increased pressure under the car manifests in rear lift (the reason Lotus added a spoiler to the Elise design). The Exige actually requires a wing to compensate. It's not for looks. Engineers also added front aero to compensate for aero inefficiencies of the Elise design.

Bottom line, the Elise is a street/production car designed for sub-80mph aero performance. Get it to 135mph and it's freaking SCARY. It wants to get airborne. The front end has been redesigned to move air around/over the car and not under the car. It's similar to the GT1 front end, or Porsche GT1 front ends. Additional drag, yes. Additional front aero performance... 100% better. 400+ whp will compensate for that drag, creating better airflow at 150mph. American race tracks have up to one mile straights. Want good track times, you better make use of high speed.

SO 1742lb = 792kg by my calcs which is 30-40kg heavier than most S1 elises with 11kg batteries etc etc [I am guessing yours has a Red Top?]


given Scuffers gives this;-

with lightweight tank, clams, seat all he can manage...and still has 60;40

your result is interesting

[KingK_series]

[quote="MacLotus
You appear to believe the Elise was designed aerodynamically for the track at high speed. In fact, it was not. The Elise has a front end that funnels air under the car vs. around the car. That increased pressure under the car manifests in rear lift (the reason Lotus added a spoiler to the Elise design). The Exige actually requires a wing to compensate. It's not for looks. Engineers also added front aero to compensate for aero inefficiencies of the Elise design.

[/quote]


not at all, it was designed as a 120bhp road going convertible with my uncles' concept of light weight at it's heart - which is after all Colin Chapman's abiding principal.


However i believe the moulded spoiler was not part of the original design , but was added to quell rear lift, leaving the front air dam less which means the car has more load at the rear than at the front - tending to front end lift - which is my experience.

[MacLotus]

I'm not sure what you mean... or where you're coming from, but my sense tells me your just provoking argument without intellect. Yes, my 2.4L upgrade added 100lbs. Well worth the power gained. Being here in the US without access to Rover repair parts, I can't afford to have an engine that requires constant attention/rebuilds. I think everyone will agree that the Rover engines are crap. You might be proud of them, but they are what they are... undependable.

To point... Are you a simple purist who can't stand to see modifications to another car, or just some dork looking to offend. If this build is not your cup of tea... Move on. Your approval is neither desired or needed. Good day sir!