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Discussion Starter #1 (Edited)
Starting to rebuild the 2004 Challenge Car this winter, has LOTS AND LOTS of track miles and needs more power, the series is dead here in the NW and I have to run with 600+ horse power cars so time to update engine and drive line.

New Engine:

302 block with custom 3.3 inch stroke Jack Roush crank. It has eagle 5.4 inch H- beam rods with .927 pins, crank pin is 2.1 inches. It has custom Ross 2618 forged pistons with a compression height of 1.15 inches. Pistons have a net zero dish, and block is zero decked, with the 64 cc heads and a .041 gasket, compression ratio is 10.2:1.
Heads are ported and polished world 200, with Manley severe duty stainless valves and a tulip exhaust valve. Valves measure 2.02. and 1.6 inches + .100 long. Springs are comp 930 with titanium retainers and 10 degree locks. Cam is Crane F-256. solid flat tappet. Power band is 4000-7400. Specs are duration 256-264 @.050. Lift .581, .601. Lobe separation is 106 degrees, installed at 102. New plasma moly speed pro rings # R9771. 1/16-1/16-3/16. Gap is .021 top. .025 second cylinders have a fresh plateau hone. A Victor JR manifold single plane manifold with Holly 750.

Transmission G-Force T-5
G-Force case and road race gears (26 tooth spline) 2.42 first gear


More to come as we start the refresh project
 

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Just have to figure out the power to weight ratio. I wouldnt think you need 600hp to compete with cars weighing 1000lbs more. What are the cars in your class? Judging by the stroke and deck height, its gotta be somewhere around 340 cubic inches depending on the bore, I would think you should be able to make 450 hp with that combo. What are you shooting for. Good luck with the refresh, sounds like youre having a lot of fun with it!

Mike
 

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Discussion Starter #4
So Dyno was at 532hp, the rear is 3:27 gears. So don't forget that 1000 lbs cars are harder to stop and takes more time and suspension also matters, as I run with them now and they range from 5 to 6 seconds faster so the 500hp in a 2300 lb car should be enough to keep close if not ahead
 

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Discussion Starter #5 (Edited)
So new exhaust as with the challenge engine I was at 98 db with augers so needed to be quiter, so went with flowmaster Slimline mufflers with baffles (no packing to wear out) and added some 9" muffler inserts that are removeable and also tips that can be turned to avoid sound meter. Thanks to Tom Ryon for the fabrication
 

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Discussion Starter #6
Needed to bypass the heater, and don't like the caps to plug up water pump so Tom Ryon welded it up for me
 

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Discussion Starter #7 (Edited)
It is a 331 CI engine
 

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Raise the compression ratio and you can get close to 600 hp. That's what I make at 7100 rpm with 13.5 to 1.
 

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Discussion Starter #9
Need to run on pump gas and that would be changing my octane requirements
 

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UrQ/Tony,

I'm interested in your mods, especially suspension. Are you still planning to run a series/class? If so, what? Will you be changing brakes, suspension & tires from the required Spec Series requirements?

Currently building a 2016 Challenge Car but not planning on sanctioned events, just HPDE and street fun. Long ways to go, chassis is still bare.

Jim
 

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Discussion Starter #11
UrQ/Tony,

I'm interested in your mods, especially suspension. Are you still planning to run a series/class? If so, what? Will you be changing brakes, suspension & tires from the required Spec Series requirements?

Currently building a 2016 Challenge Car but not planning on sanctioned events, just HPDE and street fun. Long ways to go, chassis is still bare.

Jim
So I think the suspension is just about right, as the new engine will not add weight, I hope to lighten the car to about 2200, as right now I'm at 2430 wet (w/o driver). I run the new FFR spindles and roll bar (front only), I did beef up the rear 3 link, as I broke it last year, no fun when you going over 100mph.

I will run vintage class (SOVREN, SCCA, SVRA, etc.) and some ITE class (SCCA). The breaks are great as I run the Challenge series brakes and I have not had issues, I don't think I will have any with new engine and faster speeds either. I will go back to the 275-40-17 tires (series used to run these but went to 255-40-17) and continue to run Toyo RR.


So basically my plan is to keep the car setup as it is now from the challenge series with exception of engine, exhaust, radiator. This may change as I get into it this winter
 

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Tony,

Thank you for the info.

What are your plans for reducing weight? Pulling 200# may take some creative magic.

I just weighed my chassis with an aluminum 2015 IRS center installed but otherwise bare, it's 584#on scales (393R/191F) or about 500# w/o the diff/center section. I've added a forward roll bar, center down to the dash and additional floor plates along with other changes. I'm hoping I stay at about 2,400# with an aluminum 427W.

Jim
 

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What did you do to the 3 link to beef it up? I had 3 link on my car without any of the VPM braces or welding and it stood up pretty well to 650hp. When I swapped out to Levy's 5 link the old 3 link bracket had spun a bit on the rear. Never broke though so I was lucky I guess.

Mike
 

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Discussion Starter #14
What did you do to the 3 link to beef it up? I had 3 link on my car without any of the VPM braces or welding and it stood up pretty well to 650hp. When I swapped out to Levy's 5 link the old 3 link bracket had spun a bit on the rear. Never broke though so I was lucky I guess.

Mike
Most of the challenge series folks have broken the 3 link, it breaks where its bolted to the fame on the passenger side, up by the fuel cell. also where the bar attaches to the drivers side rear 4" tube, these are the weak points
 

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Discussion Starter #15
Tony,

Thank you for the info.

What are your plans for reducing weight? Pulling 200# may take some creative magic.

I just weighed my chassis with an aluminum 2015 IRS center installed but otherwise bare, it's 584#on scales (393R/191F) or about 500# w/o the diff/center section. I've added a forward roll bar, center down to the dash and additional floor plates along with other changes. I'm hoping I stay at about 2,400# with an aluminum 427W.

Jim
Change out the bell housing, remove the EFI wiring, aluminum drive shaft, lighter flywheel. I need to also think more on other ways to reduce, I have added roll cage and anti-intrusion protection, I doubt that I will remove that though.
 

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Tony,

I've thought about or made some of the changes you've indicated.

Bought a lightweight ACT steel flywheel, 14.5#, original steel is 23#. This is a benefit in weight and rotating mass.

The QuickTime bell housing and plate is 25#, this is a bit lighter than a McLeod or Lakewood. I'd guess that a Ford aluminum would be about 14#. SCCA and NASA don't seem to make the scattershield a requirement.

The old Optima RedTop is about 40#, I'm planning on a Braille 3121 at 21#. There are smaller ones that weigh 11-15# but there may be a power output issue. Then there's the Li-On at 5-8#.

Do you think that an aluminum driveshaft would reduce sufficient weight to make the change worthwhile?

Did you need to add ballast to meet weight / HP requirements for the series?

Are there lighter wheels that meet your needs? Seems that there's a huge spread in wheel weights.

My previous Superformance cars were about 2650-2700# so anything under 2500 will be a great reduction.

I'm weighing parts as I collect and assemble. Also working on a spreadsheet that calculates corner balance with part location. Seems to be working to show the effects of changes.

It's great to hear from a racer.

Hope you make your goals, I'll be following your results. Please keep posting.

Thanks,

Jim
 

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Most of the challenge series folks have broken the 3 link, it breaks where its bolted to the fame on the passenger side, up by the fuel cell. also where the bar attaches to the drivers side rear 4" tube, these are the weak points
Ahh so its more of the main bracket assembly that breaks under the extreme side loads, makes sense. My problem was with the banana bracket. Thanks for the follow up and good luck with the upgrades.

Mike
 

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Discussion Starter #18
Ahh so its more of the main bracket assembly that breaks under the extreme side loads, makes sense. My problem was with the banana bracket. Thanks for the follow up and good luck with the upgrades.

Mike
I have my bracket welded on, so it's been on track since 2004 and no issues with the bracket. If I were drag racing I think I would look at things a little different but I'm dumping a lot of instant torque on the rear, just constant torque.
 

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Discussion Starter #19
Body off and at the body shop for damage repair, now to remove engine and trans and replace with new engine. Need to be complete by mid April as race season starts last week in April here in NW.
 

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Discussion Starter #20
Here is the dyno sheet from the engine
 

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