Road Race Track/AutoCross 351w

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MadBill
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Re: Road Race Track/AutoCross 351w

Post by MadBill »

Was your car running EFI in the video? It sounded a lot like a fuel-related stumble near the end.
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Re: Road Race Track/AutoCross 351w

Post by frnkeore »

As a critic on the driving style, I didn't see or hear any use of the brakes and if you use a later apex, you can get on the throttle, faster and longer.

In general, your much slower on corner exit, with a early apex. Trail braking, when going into a late apex, is usually the way to get the best result.

Late apex, involves entering from as far as possible to the opposite side of the corner, before turn in. Trail braking will give you the best front traction, on turn in. It's a balancing act though, if you stay on the brakes to long, the rear will come around. Seat time is your best friend!

I've never done Auto X, just SCCA road racing. In SCCA, you have to go through at least 2 schools before they let you run in a actual race. In the schools your given critics of your driving and schooling of where you need improvement, as well as how to improve.

Do they have anything like that, in Auto X?

One thing that I would, whole hardheartedly suggest is to spend a big hunk of your money on a drivers school.

I don't know where you live but, in Oregon, they have this organization:

http://www.teamcontinental.com/sub/drivers-training/

I've been formula racing since 1973 but, I used the above club, to run my street, 240 SX at PIR (Portland International Raceway). For first time drivers, they put a trained and licensed driver, in with you and he can give you live, real time training, as you drive.
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Re: Road Race Track/AutoCross 351w

Post by Sparksalot »

^^^
I can hear and see in the video how you're driving the car. Yes, your engine and gearing setup isn't the best but you'll gain far more progress in performance by learning how to drive well from expert teachers than tweaking your power plant and car. Please seek that training.

After that driver training is completed its time to work on the vehicle to improve its performance. There's lots of room for it with what you have.

Best of good luck going forward.
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Re: Road Race Track/AutoCross 351w

Post by DavidHarsay »

I've been autocrossing for close to 20 years but I'm not an expert or National caliber guy, but a little bit if experience.

I think having difficult to manage engine performance really hurts in autocross and it's tough to refine the driving technique if you're having to compensate for drivability... as for the tuning, it's not an autocross type engine that's for sure. Torque is king but smooth drivability is even more important. The cam should be much less aggressive, the 1.5 rocker experiment may help but cam timing is for top end power sacrificing anything below 3,000 rpm and idle for sure (brakes if it's not hydroboost)... and for AFR targets you can tune for crisp power or smooth power... down low 14.0-15.0 is very crisp and even a little jerky sometimes, whereas 13.2-13.6 us usually much smoother, and WFO high RPM would of course need more fuel.

Here's an interesting article about the 1986 Corvette in Autocross (I happen to have one myself)

http://www.superchevy.com/features/vemp ... rvette-c4/
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Re: Road Race Track/AutoCross 351w

Post by Rick! »

Lotsa good info here.
That cam is not for autocrossing and there isn't any sugar coating or rocker ratio that's going to pull you out of a corner at 2000rpm.
Do you drive with 2 feet? If not, learning would help a lot. Auto X is all about being smooth, slow hands and the precise amount of throttle at the right time, not stab and steer.
You can try a few things with the current cam:
1. Run the valves .010 looser and see how it works.
2. Run the timing as high as the engine allows without pinging. I used to run over 25* on short tracks to improve corner pull and bring it back for longer tracks.
2. b) Run the looser valves with advanced timing and see if it is noticeably better.
If those adjustments work, find someone to help you select a new cam that has more lobe separation and maybe not quite so much lift.
I ran 3:91's in my autocrosser with a close ratio T10 and never shifted out of 2nd. You still have room to gear up a bit from your 3.73's.
If you don't want to do a cam then you're looking at a significant rear gear change, like close to 5.0 or whatever is available for your diff size (8.8?).
Make sure your tuner guy has the accel enrichment spot on so it doesn't bet soft or blubbery if you do successive blaps on the gas.
It looks like you have decent tires but they still have significant tread depth when new. Back last century, we would get VR-1s shaved from Tire Rack and be fast right out of the box. I think that is still done as Yoko endorses it on their A048s.
One thing not to overlook is how much fun your are having. If you are out there to test your skills and hear your car's exhaust and squeal the tires a little and it puts a smile on your face, that's a win.
If you want to get serious and compete regularly and maybe take a few wins, then you'll need to readjust a few things on your buggy.

I'm glad I got out of autocrossing when I did as C-Street Prepared was being taken over by Mustangs. All it took was a set of 351W heads, a set of adjustable Konis all around and the stickiest, widest rubber you could fit in the wheelwells. I got my season championship, got married and sold the car.

I autocrossed once after that and got kicked out as I put my buddies RX-3 (SCCA IT car) on two wheels at the end of a fast sweeper. I didn't think it was a big deal but the old guy running the show got his shorts in a knot over it. :)
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Re: Road Race Track/AutoCross 351w

Post by GimpyHSHS »

I didn't see all of these replies until today. I haven't been on here much lately, I have been crazy busy doing car work, school work, and...work work. I appreciate the driving critiques! I know I am not going to go rock the Nationals leaderboards or anything, I want to go fast and have fun. It would be nice to place a little higher over time, of course, but realistically, I'm 24, I've been to Hallett a total of 4 days, and this is my first year autocrossing against some good drivers. I know I need to get better myself.

My concern with the old engine was the fact that my cousin (who raced dirt track for 15 years and then has autocrossed for another 15 after) couldn't even place well in the car, even after co-driving it all year. The engine power was a real bummer. I barely beat a friend with an E Cam Cobra for pete's sake!

As an update here: we tore the car down on New Year's Eve. My cousin thought it was time for a rebuild, we had some oil leaks to fix up, and some adjustments to make. Figured we would swap the cam for something more AutoX friendly. Once we got it out, we took the passenger side head off and found a cracked piston in the #4. Amazingly, it didn't tear up the cylinder wall or so much as scratch the head.

Then we had a big decision to make: do I buy a set of pistons and go .040" over (the engine wasn't in BAD shape, but it wasn't in GREAT shape inside) on stock rods, stock crank, and stock block and put it back together OR do I go ahead and work toward building the engine I've been planning in a Spreadsheet for the past year or two?

A careful examination of finances suggested I would be able to build my "dream" short block, something that even I couldn't break. So I contacted several builders to discuss options. The main two I considered were Kuntz Co and Craft Performance, both about an hour from me. I didn't get an awful lot of feedback from Craft. And my dad has had an engine there for well over a year that still isn't finished (something about no one making custom pistons right now?). So I went for Kuntz and they got started on the short-block build. We settled on a 427" Dart block with forged rotating assembly.

I was planning to reuse my World Products Windsor SR 200cc heads, with a conversion to a hydraulic roller, hoping to reuse as much as possible to keep the price down and give me a strong foundation for the future. But then I re-examined finances and realized that, with a few Ramen noodle meals a day, I could probably swing just going all the way with new heads better matched to a 427w.

So I decided to go with AFR 205s, which Kuntz wanted to flow bench and possibly do some more work to. I declined, because of budget reasons. But they ended up having trouble finding them anyway, so they offered me some cheaper castings. They are still going to do 2.08/1.6 SS valves, titanium retainers, .120" wall pushrods, around 10.8:1 compression, and they're going to do the port work and flow-bench work, for around the same price as the AFRs. The builder had said he wanted to get a little closer to 220cc ports with more cross-section (and some other jibber-jabber that was a little over my head if I am being honest).

So the new engine is going to look a little something like this:
-Dart SHP block, 4.125” bore, 9.5” deck height
-Scat Forged Crank, 4.00" Stroke, 2.75" Main, internally balanced
-Scat 6.200 H-Beam Rods
-Diamond Forged 2618 Pistons 6cc VR
-Kuntz CNC Ported/Matched Heads, 220cc intake ports, 2.08/1.60 SS valves
-Titanium Retainers
-Kuntz spec'd springs
-Johnson Short Travel Hydro Roller Lifters
-MLS Head Gaskets
-Double Roller Timing Set
-FRPP DRS Road Race Oil Pan, pickup, gasket
-Melling Pump/ARP Driveshaft
-.120" Wall Pushrods
-ARP Head Studs
-McLeod aluminum flywheel and Ram Clutch, FRPP pilot bearing
-Victor Jr Intake
-Holley Sniper 800cfm EFI
-Kuntz Cam, 243/255 @.050, 111 + 3 .660 lift
-Innovator West 205 Balancer
-BBK 1-¾” LT Headers, will be 3” pipe back to the rear end, then turned down

It was also time for some more changes while the engine is out and I have some free time:
-MM K Member MM MMKM-1
-MM Steering Rack Bushings MM MMST-6
-MM Bumpsteer Bolt Through MM MMTR-3
-MM Control Arms MM MMFCA-11
-MM Swaybar Relocation Bracket MM MMFSB-51
-Universal Sway Bar Bushings MM 9-5168G
-MM Pinion Snubber MMPS
-MM Solid Motor Mounts MMSMM-1
-MM Bumpsteer Gauge
-SS Brake Lines for the Rear (already had them in front)
-AC Compressor Removal (conservatively estimated at 10 pounds)
-MAF Racing Front Bumper Support (another 10 pounds)
-ABS Manifold (car has never had functioning ABS anyway, this manifold bolts in place of the ABS block and shaves about 10 pounds off the nose)

The weight decreases in the front, plus lighter flywheel, etc) should help offset the added weight of the Dart block. I ran the numbers on the rotating assembly, and the new crank, rods, and pistons are all lighter than what I had before.

The new engine should be done by the latter part of May. Then we will break it in on the dyno and do some baseline tuning/power pulls. The hope is to have the new K Member and control arms (currently backordered, but supposed to be here by end of May) in in time to set the engine back 1", but if we don't have time for that, no biggy. The goal is to have the car ready for a shakedown AutoCross weekend on June 12th and 13th, then on track at Hallett the 17th and 18th for the Mid-America Ford and Shelby event. Should be a pretty balls to the wall couple weeks in June!
1995 Mustang GT (AutoX/Road Course Car)- Missing an Engine at the Moment... ](*,)
Tremec TR-3550 Transmission, 3.73 gears
Maximum Motorsports Coilovers, 400/275 lb/in Springs
MM Torque Arm, Fays2 Watts Link
Way too much else to list...issa money pit.
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Re: Road Race Track/AutoCross 351w

Post by Tuner »

never mind :lol:
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Re: Road Race Track/AutoCross 351w

Post by 6sally6 »

Wonder if.........shorter wheel/tire combo with the dual plane and more ignition advance would have made a difference?
Guess we'll never know!
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Re: Road Race Track/AutoCross 351w

Post by Walter R. Malik »

GimpyHSHS wrote: Fri Dec 04, 2020 10:49 pm Hello folks, I am new to the boards, but I'm no stranger to reading a lot from the bright minds of racing here.

Here's the story: I bought a used engine I found on Racing Junk. I got a good enough price that the sum of the parts made sense to buy it. I've listed the full specs that I know below. I didn't put it together and I've never had it completely apart, so I don't know everything. I had a carb on it for a little while before deciding to convert to EFI. I went with a Holley Sniper throttle body injection system.

The car is a 3100lb 1995 Mustang GT. I use it for track days and autocross only pretty much, but I do occasionally take her for a leg stretch on the street. Fairly extensive braking, tire, and suspension changes. Has a Tremec TR3550, aluminum driveshaft, 3.73 gears, things like that.

My only real complaint about the car now that I've got the suspension mostly dialed in is the engine and tune. I know that the cam is fairly large for what I'm doing. It idles at around 6 in/hg. Autocross events are nearly entirely run in 2nd gear. I may get up to 70mph on one part of the course, then go down to 30, then back up to 50, etc. The car pulls...ok? but struggles coming out of the slow parts of the course. I always felt like it had decent power, but my cousin with much more experience behind different wheels has said he doesn't think the engine is "explosive" enough, at least not like the ones he's driven before. Recently I rode shotgun in my buddy's 3.08 gear 1995 Cobra with a B Cam and the MAF unplugged (his idea of a tune). His car felt like it pulled harder than mine!

Here's a video of mine: https://www.youtube.com/watch?v=3t2E1_EpKd4

Toward the end, you can hear the engine struggle to go from slowing down to accelerating again.

I've been of the opinion that the cam was the problem. Too big to work down low with my gearing. But now I'm wondering if the problem lies in my tune. I've read that bigger cams need more timing at low RPMs and cruise, something I didn't realize. I figured it would be the opposite. I've been running 20*(ish) at idle, 35* cruising, and right around 34* at WOT. Since the engine is 11:1 and I'm running 93 pump, I figured that was a safe tune. My cousin was against having much "vacuum advance" (it's all electronic, obviously, with the Holley EFI, but you get my drift).

I'm curious to hear people's suggestions on where I should start the timing out. I've made some changes to the tune to try out. But in general, will a little more idle timing down low help with low end power (2000-3500) where it feels a really weak?

I'm kind of at a crossroads now, I have time after the autocross event this weekend to try out a custom cam or off-the-shelf cam that would better fit my application. I just don't want to do that if the cam I have should work for the application and the problem lies elsewhere. My cousin has suggested that he thinks the problem is in the engine, a valve hanging or a piston ring not sealing, but the leakdown test showed 90%+ across all cylinders. He has also opined that I might need a lighter flywheel (something that probably would help with the quick speeding up and slowing down we do in AutoX, but I'm not sure that's actually the issue).

Anyway, I welcome any input you folks have. I'm young and dumb, like everyone else out there was one day. If you have any questions, please just ask and I will try to clear it up. My little ADHD brain bounces around writing these posts :)

Specs on the engine:
351W + .030” overbore = 357 cu in.
11:1 compression
Aluminum Windsor Sr Heads. 200cc intake runners. 2.02/1.6 valves.
Crower 1.6 ratio roller rockers on exhaust
Crane 1.7 ratio roller rockers on intake.
Victor Jr. single plane intake.
BBK 1-¾” Long Tubes
BBK X Pipe
Flowmasters, Dumped
Holley Sniper EFI
Holley Hyperspark Distributor
Holley Hyperspark Ignition Box
Holley Hyperspark Coil
Taylor Spiro-Pro 8mm Wires
Autolite 25 Plugs
AEM 10-1005 Fuel Pump
Sumped/Baffled Tank
Aeromotive 13129 Bypass Regulator
Aeromotive ORB-10 Fuel Filters

Cam profile:
Schneider Cams Solid Flat Tappet
Part Number: 13032
Grind Number: 284-92F
Intake Duration (gross): 284
Exhaust Duration (gross): 292
Intake Duration (.050”): 248
Exhaust Duration (.050”): 258
Intake Valve Lift: .600" (based on 1.7 rocker)
Exhaust Valve Lift: .584" (based on 1.6 rocker)
Lobe Separation: 106
Intake Valve Lash: .020"
Exhaust Valve Lash: .020"
RPM Range: 3000-7000


Some various other specs on the car:
Steeda Ultralite 18x9" wheels
275/35/18 Falken Azenis RT615K+
Maximum Motorsports Race RA-2 Gen 3 Coilover Struts
Hypercoil 10"/425 lb/in Front Coilover Springs
Maximum Motorsports Race RA-2 Gen 3 Coilover Shocks w/Spherical Lower Bearing
Hypercoil 275 lb/in Rear Coilover Springs
Stiffler's FIT Chassis System (Subframe Connectors, Jacking Rails, Web Bracing)
SR Performance Strut Bar (Modified to Clear 351w)
Maximum Motorsports Caster/Camber Plates
Maximum Motorsports Torque Arm
Fays2 Watts Link
MM Rear Shock Mounts
Steeda Front and Rear Swaybars
Steeda Aluminum Radiator
Steeda Rear Lower Control Arms
Steeda Front Offset A-Arm Bushings
Steeda Battery Relocation Kit
2000 Cobra R Brembo Brakes
Raybestos ST47 Pads (Front)
Raybestos ST43 Pads (Rear)
Wilwood 570 Brake Fluid
Stainless Front Brake Lines
Russell Speed Bleeders
Tremec TR-3550 Standard Ratio Transmission
Aluminum FRPP Driveshaft and Loop
3.73 Rear Gears
Steeda Tri-Ax Shifter w/Hurst Ball
Steeda Adjustable Clutch Cable, Quadrant, and Firewall Adjuster
Personally, I would simply change the intake manifold to a port matched, Edelbrock 2-Plane "Air Gap" #7581.
http://www.rmcompetition.com
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GimpyHSHS
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Re: Road Race Track/AutoCross 351w

Post by GimpyHSHS »

That would've been an option a while back. We certainly discussed gear swaps, intake swaps, cam swaps, etc. I didn't really have the play-around money last season to test out changes, and I was mainly focused on the suspension anyway. That makes a much bigger effect on the car in AutoX/tracking, and what I had before wasn't great. I also didn't want to invest much into that engine...after I saw what we had, I decided a different shortblock was the better route long term.

I am very excited about the new plant and other changes though! Ready to get it back together and get it back out there!
117589130_2683310828549849_5888601465576115306_n.jpg
118516789_937263333452150_8387089373837772866_n.jpg
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1995 Mustang GT (AutoX/Road Course Car)- Missing an Engine at the Moment... ](*,)
Tremec TR-3550 Transmission, 3.73 gears
Maximum Motorsports Coilovers, 400/275 lb/in Springs
MM Torque Arm, Fays2 Watts Link
Way too much else to list...issa money pit.
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Re: Road Race Track/AutoCross 351w

Post by Tuner »

6sally6 wrote: Thu Apr 01, 2021 4:55 pm Wonder if.........shorter wheel/tire combo with the dual plane and more ignition advance would have made a difference?
Guess we'll never know!
The cylinder heads on the OP's original engine combo are fast burn and do not at all like advance much over 26 or 28 degrees and that only at high RPM. The WOT low RPM range where he was complaining about the engine struggling may haver been better suited with timing in the 20-22 area. And, the 25 plug is too hot. I have done several mechanical distributors for SBF engines with similar heads and have found they don't like old school timing numbers at all. Timing can be advanced too much for best power and not knock, just have less power than if it were ideal for best output. The above assumes engine is hot to endurance racing temperature, water and oil.
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frnkeore
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Re: Road Race Track/AutoCross 351w

Post by frnkeore »

Well, with that much additional hp, it will be a little harder to control, maybe a lot.

In road racing, it's all about entering a corner and accelerating smoothly out of it. You don't want the tires to spin, a controlled drift, is much faster. Seat time is what will get you to advance your skills and a instructor will help, a lot!

I would suggest two simple things. First have them advance the am, at least 2 more degrees. That will give you a little more average hp and it may not come on so strong as the rpm increases. It won't effect it a lot at higher rpm and it's easily reversed.

Second, put in a 1/2 throttle stop or, disconnect the secondary's, until you get smoother. It will be very frustrating, trying to control the power on the short acceleration areas and having to get set up, for the next corner.

My best suggestion, if you want to be very good at what your doing, is to get the best available driving help, you can afford.

https://duckduckgo.com/?q=road+racing+s ... =h_&ia=web

Find one near you. HP is easy, honing your drivers skills, isn't.
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Re: Road Race Track/AutoCross 351w

Post by Walter R. Malik »

Walter R. Malik wrote: Thu Apr 01, 2021 5:16 pm
GimpyHSHS wrote: Fri Dec 04, 2020 10:49 pm Hello folks, I am new to the boards, but I'm no stranger to reading a lot from the bright minds of racing here.

Here's the story: I bought a used engine I found on Racing Junk. I got a good enough price that the sum of the parts made sense to buy it. I've listed the full specs that I know below. I didn't put it together and I've never had it completely apart, so I don't know everything. I had a carb on it for a little while before deciding to convert to EFI. I went with a Holley Sniper throttle body injection system.

The car is a 3100lb 1995 Mustang GT. I use it for track days and autocross only pretty much, but I do occasionally take her for a leg stretch on the street. Fairly extensive braking, tire, and suspension changes. Has a Tremec TR3550, aluminum driveshaft, 3.73 gears, things like that.

My only real complaint about the car now that I've got the suspension mostly dialed in is the engine and tune. I know that the cam is fairly large for what I'm doing. It idles at around 6 in/hg. Autocross events are nearly entirely run in 2nd gear. I may get up to 70mph on one part of the course, then go down to 30, then back up to 50, etc. The car pulls...ok? but struggles coming out of the slow parts of the course. I always felt like it had decent power, but my cousin with much more experience behind different wheels has said he doesn't think the engine is "explosive" enough, at least not like the ones he's driven before. Recently I rode shotgun in my buddy's 3.08 gear 1995 Cobra with a B Cam and the MAF unplugged (his idea of a tune). His car felt like it pulled harder than mine!

Here's a video of mine: https://www.youtube.com/watch?v=3t2E1_EpKd4

Toward the end, you can hear the engine struggle to go from slowing down to accelerating again.

I've been of the opinion that the cam was the problem. Too big to work down low with my gearing. But now I'm wondering if the problem lies in my tune. I've read that bigger cams need more timing at low RPMs and cruise, something I didn't realize. I figured it would be the opposite. I've been running 20*(ish) at idle, 35* cruising, and right around 34* at WOT. Since the engine is 11:1 and I'm running 93 pump, I figured that was a safe tune. My cousin was against having much "vacuum advance" (it's all electronic, obviously, with the Holley EFI, but you get my drift).

I'm curious to hear people's suggestions on where I should start the timing out. I've made some changes to the tune to try out. But in general, will a little more idle timing down low help with low end power (2000-3500) where it feels a really weak?

I'm kind of at a crossroads now, I have time after the autocross event this weekend to try out a custom cam or off-the-shelf cam that would better fit my application. I just don't want to do that if the cam I have should work for the application and the problem lies elsewhere. My cousin has suggested that he thinks the problem is in the engine, a valve hanging or a piston ring not sealing, but the leakdown test showed 90%+ across all cylinders. He has also opined that I might need a lighter flywheel (something that probably would help with the quick speeding up and slowing down we do in AutoX, but I'm not sure that's actually the issue).

Anyway, I welcome any input you folks have. I'm young and dumb, like everyone else out there was one day. If you have any questions, please just ask and I will try to clear it up. My little ADHD brain bounces around writing these posts :)

Specs on the engine:
351W + .030” overbore = 357 cu in.
11:1 compression
Aluminum Windsor Sr Heads. 200cc intake runners. 2.02/1.6 valves.
Crower 1.6 ratio roller rockers on exhaust
Crane 1.7 ratio roller rockers on intake.
Victor Jr. single plane intake.
BBK 1-¾” Long Tubes
BBK X Pipe
Flowmasters, Dumped
Holley Sniper EFI
Holley Hyperspark Distributor
Holley Hyperspark Ignition Box
Holley Hyperspark Coil
Taylor Spiro-Pro 8mm Wires
Autolite 25 Plugs
AEM 10-1005 Fuel Pump
Sumped/Baffled Tank
Aeromotive 13129 Bypass Regulator
Aeromotive ORB-10 Fuel Filters

Cam profile:
Schneider Cams Solid Flat Tappet
Part Number: 13032
Grind Number: 284-92F
Intake Duration (gross): 284
Exhaust Duration (gross): 292
Intake Duration (.050”): 248
Exhaust Duration (.050”): 258
Intake Valve Lift: .600" (based on 1.7 rocker)
Exhaust Valve Lift: .584" (based on 1.6 rocker)
Lobe Separation: 106
Intake Valve Lash: .020"
Exhaust Valve Lash: .020"
RPM Range: 3000-7000


Some various other specs on the car:
Steeda Ultralite 18x9" wheels
275/35/18 Falken Azenis RT615K+
Maximum Motorsports Race RA-2 Gen 3 Coilover Struts
Hypercoil 10"/425 lb/in Front Coilover Springs
Maximum Motorsports Race RA-2 Gen 3 Coilover Shocks w/Spherical Lower Bearing
Hypercoil 275 lb/in Rear Coilover Springs
Stiffler's FIT Chassis System (Subframe Connectors, Jacking Rails, Web Bracing)
SR Performance Strut Bar (Modified to Clear 351w)
Maximum Motorsports Caster/Camber Plates
Maximum Motorsports Torque Arm
Fays2 Watts Link
MM Rear Shock Mounts
Steeda Front and Rear Swaybars
Steeda Aluminum Radiator
Steeda Rear Lower Control Arms
Steeda Front Offset A-Arm Bushings
Steeda Battery Relocation Kit
2000 Cobra R Brembo Brakes
Raybestos ST47 Pads (Front)
Raybestos ST43 Pads (Rear)
Wilwood 570 Brake Fluid
Stainless Front Brake Lines
Russell Speed Bleeders
Tremec TR-3550 Standard Ratio Transmission
Aluminum FRPP Driveshaft and Loop
3.73 Rear Gears
Steeda Tri-Ax Shifter w/Hurst Ball
Steeda Adjustable Clutch Cable, Quadrant, and Firewall Adjuster
Personally, I would simply change the intake manifold to a port matched, Edelbrock 2-Plane "Air Gap" #7581.
Just so you're not misinformed ... a cam 243@.050" using hydraulic roller lifters is probably MORE duration off the seat than one at 248@.050" with solid rollers lashed at .020", although the total lobe area may be less.
However, your engine is now about 17% bigger, too.
http://www.rmcompetition.com
Specialty engine building at its finest.
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Re: Road Race Track/AutoCross 351w

Post by j-c-c »

A few others have touched on this angle, but Auto-X and closed track road racing are vastly different animals IMO engine wise. So is real(?) road racing ever in the mix, or are we focusing mainly on autox?
hoffman900
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Re: Road Race Track/AutoCross 351w

Post by hoffman900 »

j-c-c wrote: Fri Apr 02, 2021 11:37 am A few others have touched on this angle, but Auto-X and closed track road racing are vastly different animals IMO engine wise. So is real(?) road racing ever in the mix, or are we focusing mainly on autox?
Looks like autocross and track days.


For track days, don’t even worry about going faster in a straight line and focus on keeping the engine together. Road racing is very hard on equipment (engine, brakes, etc). Odds are you’ll be driving nowhere near the limit (and shouldn’t be).
-Bob
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