160 horsepower engine requires frame gusseting helps

[Frankster1955]

I have a 1966 S3 SE. So, I decided to do a total refresh on this car. Professionals are undertaking this work not me. I am going to have MWE rebuild my engine with 45 DCOE Webers, long throw crank, some cams and extensive porting 160 hp with 150 to the rear. I do not plan to race the car, just spirited backroad fun with ostensibly enough reliability to come to events and maybe meet other Lotus mavens.

But to the point, I rather think it is obvious gusseting is needed to my original chassis at both the motor mounts and where the differential assembly attaches to the rear of the frame. I have bought a stiffener bar from for the differential. Yet to see this item. Bought it from DBean on Ken's recommendation. 80 bucks. Also bought advanced screws for the half shafts. Rotoflexes are going away of course. New TTR shocks and springs for "fast road" are being placed --so the whole thing is coming apart for renovation. Upgrading brakes. New radiator. Swirl Pot. Fan. Steering rack. I do not want to take the body off the car for the paint is perfect.

Five areas of expertise required plus any insight you may have:

1 I ask for photos/ diagrams of where to gusset the motor mount /frame area.
2 I need gusseting at the rear as well. Are there prefab parts or a kit to weld in place at either end? Anyone have a pattern we can copy from which we can cut, perhaps from a project you have completed?
3 Its a fiberglass car. Welding is problematic. Insulating the body tips. Could bolts hold the pieces in place?
4 What welding to use?
5 To replace the rotoflexes and improve the car performance, what bolt ons do you recommend. Brands?

Photos or diagrams most appreciated.
Frank in Cincinnati

[patrics]

Hi Frank,

If you are going to start welding the chassis then best to remove it completely.

Regarding photos check out postings from "cabc26b" he has posted detailed photos of the chassis modifications.

When welding the chassis care would be needed so as to keep it in alignment.

Changing from Rotoflexes to an other types does not mean you have to change from knock offs.

Regards
Steve

[mbell]

Regarding photos check out postings from "cabc26b" he has posted detailed photos of the chassis modifications.

viewtopic.php?t=13513&f=19&start=0#p61285

Personally I am not sure you really need to re-enforce much for 160BHP. Certainly the diff brace and CV joints probably a good idea.

[nmauduit]

Regarding photos check out postings from "cabc26b" he has posted detailed photos of the chassis modifications.

viewtopic.php?t=13513&f=19&start=0#p61285

Personally I am not sure you really need to re-enforce much for 160BHP. Certainly the diff brace and CV joints probably a good idea.

I share mbell's opinion : what may make the chassis over flex would be high performance modern tyres on a track at the limit, if you're only into "spirited driving" on the road with road legal tires, and your stock chassis in general good condition (no previous corrosion or cracks from accidents etc) should take it imho.

[rgh0]

After 40 years of racing on a standard Lotus chassis with engines going from 120 hp to now over 180 hp and tyres getting progressively better and stickier there are a few things needed based on my experience FWIW

1. You need to replace / upgrade a lot of the drive train to cope if your pushing it to 10/10 on a track. TThe details of what and when vary depending on how your using the car, the harder you use it the more you need to upgrade. Donuts and diff output shafts are the beginning for an upgraded road car. A reinforcing brace for the diff is also a good idea especially if you have the early small eared diff. ElanTrikBits have a much better brace than the crude Lotus version they added in later cars. TTR had an article on this area on their website

2. The standard chassis itself only has a few weaknesses in my experience and much of the mods done with the "26R chassis upgrade" add weight without doing much else. However there are a few key areas of weakness that you do need to address if seriously upgrading the car for racing. How much is needed for a road car depends on how much you like your road car to have racing capabilities

a. Rear suspension top of strut brackets need stiffening to stop them buckling especially if fitting stiffer springs and dampers at the rear. This happens overtime even in standard road cars. Plus 2 had these mods in their chassis later chassis from the factory as they clearly had problems with their greater weight
b. Engine mount brackets will crack on the top but not really an issue as these cracks do not spread. The real issue is around the bottom where they go into the chassis and where the roll bar also mounts. it can crack in this area especially with competition engine mounts and stiffer roll bars
c. Diff torque rod securing bolts can crack in the chassis especially if allowed to get loose. Some reinforcing here can help ... Though I have never needed it but then again I never let them get loose

cheers
Rohan

[2cams70]

Jeez - no wonder Colin Chapman didn't approve of the Elan being used for rallying!

Remember too it's not horsepower that stresses the chassis. It is torque. A 160HP engine does not necessarily have significantly more torque than a 130HP one if the additional 30HP is just achieved by maintaining the same torque but at a higher engine speed.

[elans3]

I wouldn't fit 45 DCOE's, not necessary for 165 bhp. I used to own an ex hillclimb Elan whose engine was built by one of the top UK Twincam men - Jim Evans. It was obviously bult for torque for the hills, but produced 165bhp on 40 DCOE's and 34mm chokes. I'd only go to 45's if I needed 36mm chokes or bigger.

[2markvo]

Kelvedon Lotus sell a 26R chassis upgrade kit, (RACE26RCK01). For a street Elan, it can't weigh that much extra.