FIA -How fast

[ERA2076]

Where is the safe upper end?
Do they get light or other handling problems at speed?
What speed?
Is there setup to get them to run fast?
Is there enough brake with 15's and rear out boards?

Mine is apart and we are working to set it up for open track - drop weight - get suspension to articulate - new engine & drive train.

We are working on 331- A5 - ERA rear - Wilwood front - 15" Avon on Trigo - Penske DA - Comp Windshield. Currently we have the front suspension out of the car and are rebuilding it so it will freely articulate.

Thoughts on running a 225 on the front?

Are the 250 springs enough? I run calculations and come up with heavier springs i.e 325.

Lot's of questions I realize, but they are all related.

x-cliff

[strictlypersonl]

Originally Posted by ERA2076

Where is the safe upper end?
Do they get light or other handling problems at speed?
What speed?
Is there setup to get them to run fast?
Is there enough brake with 15's and rear out boards?

We serviced a track FIA with roughly 600bhp with that setup. You just need appropriate pads.

Thoughts on running a 225 on the front?

That will work.

Are the 250 springs enough? I run calculations and come up with heavier springs i.e 325.

My recollection is that we used 350 or 375 lbs/in in the front, 550 lbs/in in the rear.

[1985 CCX]

Keep in mind the original cars were leaf-spring (buggy style) and much different than a coil over car. You will be better than original FIA car as your suspension is well engineered via ERA.

Original cars were in the 400hp range, as Bob stated they are familiar with up to 600. You will be fine...

Your rear gear ratio will dictate speed, these cars were not smooth in the wind hence the Coupe and GT40. If memory serves me well 150 ish was about the limit. More hp and higher gears can get 427 cars in the 200mph range. My old CCX was steady at 155 but higher was not possible as I maxed gear and hp at the time. I ran 250lb springs in the rear, Jag type

Good luck

[ERA Chas]

Originally Posted by 1985 CCX

My old CCX was steady at 155 but higher was not possible as I maxed gear and hp at the time. I ran 250lb springs in the rear, Jag type

Good luck

These are exactly my numbers. At 155, it's a struggle to keep it straight in the wind. The FIA is slightly worse in that regard. And don't snap-shift-you'll unload the tires and it's like glare ice.
Get the ride height as low as you can and follow Bob's spring recommendations. He's talking about Joe Rodameister's car-a track monster.
Of course you don't always need 155 to win races...

[ERA2076]

Thanks for the thoughts -

Bob - the 550 are with ERA rear?

CCX - Yes - I was just checking to see how much if any difference in the ERA compared to the originals.

Chas - 155 - Assuming we build enough to get there, that might be over the top for me. Comforting to know it should be stable @ 130. I'd like to try 140 some time if we have enough to get there.

I have a 3.54 rear - not sure how that is going to work - we may need to regear - I am trying to build a bit of a winder, but should end up in the low to mid 400hp.

What is considered a light (ERA) FIA. i.e how much does a well running track FIA weigh? What is the lightest anyone has built?

x-cliff

[ERA Chas]

Originally Posted by ERA2076

I have a 3.54 rear - not sure how that is going to work - we may need to regear - I am trying to build a bit of a winder, but should end up in the low to mid 400hp.

What is considered a light (ERA) FIA. i.e how much does a well running track FIA weigh? What is the lightest anyone has built?

I think you're good with a 3:54-I did that with a 3:31 and 6200RPM.
I don't know how light they've been built-I can't recall anyone doing an all out track ERA except Don Durner. And that was BB.
I saw Rodameister's car but I don't think it was gutted to any degree.
All the weight in an ERA is the chassis steel-good because it's near the CG. The ERA rear is good for 50 less pounds. The body glass is plenty thick too so that fights the CG a bit.
The real problem is the aero-there is none. The car just kites above 130. That's why I'd lower it big time and run G-7 slicks for the shallow sidewalls.

[strictlypersonl]

Duplicate reply

[strictlypersonl]

Originally Posted by ERA2076

Thanks for the thoughts -

Bob - the 550 are with ERA rear?

Yes.

I have a 3.54 rear - not sure how that is going to work - we may need to regear - I am trying to build a bit of a winder, but should end up in the low to mid 400hp.

A 331 cid/400 bhp engine will probably have peak power at 6500 rpm and be limited to 7000rpm. I would gear it to have peak power in 4th gear at 130-140 mph. That translates to a 3.54:1 dif ratio.

What is considered a light (ERA) FIA. i.e how much does a well running track FIA weigh? What is the lightest anyone has built?

With a 351, expect 2350-2500lbs. A bit more if you put a roll cage in. Not many places to remove weight.

[ERA2076]

Originally Posted by strictlypersonl

Yes.

A 331 cid/400 bhp engine will probably have peak power at 6500 rpm and be limited to 7000rpm. I would gear it to have peak power in 4th gear at 130-140 mph. That translates to a 3.54:1 dif ratio.

That is what we went for - peak @ 6300.

Originally Posted by strictlypersonl

With a 351, expect 2350-2500lbs. A bit more if you put a roll cage in. Not many places to remove weight.

The car was 2440 with the 351. New configuration is aluminum 302, light T5, light clutch assy, alum bell housing, and ERA rear. Shooting for 2300 maybe less. We Got 150 out of the trans and rear if the rear comes in @ -50.

The 351 was 425. Unsure how much we will improve here, but we should get some.

Will get a little out of the screen and fixed alum drivers seat.

[ERA2076]

Originally Posted by ERA Chas

The real problem is the aero-there is none. The car just kites above 130. That's why I'd lower it big time and run G-7 slicks for the shallow sidewalls.

On lowering the car. We were working on this when I blew it up. How much can you lower while maintaining suspension geometry? I set the height by sight and then checked the geometry and it was surprisingly close to having the front lower control arms parallel with the ground. This was with Dunlop 235 60. I am pretty sure the Avons are going to have them exactly parallel if we make no other changes because of the increase in the diameter of the tire.

When you lower them do you run the stock suspension and steering components?

How much can you lower without inducing bump steer, running out of shock, etc.? Anythings special to look out for here?

I am not building a race car. I will still run it on the street, but I would like it to handle the best we can get it without re-invent of the the wheel. That said - track performance is of higher priority than street manners. Once I get tired of throwing money down the drain we can de-tune it, bolt the windshield on, put the carpet back in, and take it to Sunday breakfast.

G-7 Slicks - 15" rim? Not familiar.

x-chr

[ERA Chas]

I have only seen FIA's with ERA suspension components-no custom track-only parts.
Since he designed that suspension, Bob is the best one to advise you about lowering and modification. A call might be best.
If you dry-sump it, you can lower it without oil pan fear. Jus sayin'...
Here is the G-7 information. They are actually called 'semi-treaded' tires. I think you can have them shaved into slicks but check with Krauss. These are the hot vintage race tire:
Roger Kraus Racing - Pricing
Click on 'Cobra tires' and a PDF will list the G-7's with price and specs.
I like your plans for the car.

[strictlypersonl]

The suspension is when fine lowering the car so far that the exhaust pipes scrape. The bump-steer curve is optimized for a lowered car, although the later steering gear setup is better and more adjustable with offset bushings. Could be a $1500 conversion though.

You don't have to worry about much else.

[ERA2076]

Originally Posted by ERA2076

Bob - the 550 are with ERA rear?

Bob - stock anti roll bars with the 3nn front - 550 rear?

[strictlypersonl]

We keep the standard anti-roll bars: 15/16" front, 3/4" rear. All the medium tuning should be done with spring rates. Fine tuning with the adjustment on the rear bar.